CN111708260A

CN111708260A - Substrate pretreatment to reduce fill time in nanoimprint lithography

Info

Publication number: CN111708260A
Application number: CN202010752918.7A
Authority: CN
Inventors: 尼亚兹·科斯纳蒂诺夫; 蒂莫西·布赖恩·斯塔霍维亚克; 刘卫军
Original assignee: Canon Inc
Current assignee: Canon Inc
Priority date: 2015-09-08
Filing date: 2016-09-08
Publication date: 2020-09-25
Anticipated expiration: 2036-09-08
Also published as: CN106842835A; SG10201607459WA; KR20200058357A; KR102466726B1; TWI708118B; SG10202102937RA; KR102115280B1; JP6141500B2; CN111708260B; JP2017055108A; CN106842835B; KR20170030051A; JP6723947B2; JP2017152705A; TW201723649A

Abstract

The present invention relates to substrate pretreatment to reduce fill time in nanoimprint lithography. A nanoimprint lithography method comprising disposing a pretreatment composition on a substrate to form a pretreatment coating. The pretreatment composition includes a polymerizable component. Discrete portions of imprint resist are disposed on the pretreatment coating, wherein each discrete portion of imprint resist covers a target area of the substrate. As each discrete portion of the imprint resist spreads beyond its target area, a composite polymeric coating is formed on the substrate. The composite polymeric coating includes a mixture of a pretreatment composition and an imprint resist. The composite polymeric coating is contacted with the template and polymerized to provide a composite polymeric layer on the substrate. The interfacial energy between the pretreatment composition and air exceeds the interfacial energy between the imprint resist and air or between at least one component of the imprint resist and air.

Description

Substrate pretreatment to reduce fill time in nanoimprint lithography

The present application is a divisional application of the chinese patent application having an application date of 2016, 9/8, and an application number of 2016108116611, entitled "pretreatment of a base material for reducing a filling time in nanoimprint lithography".

Cross Reference to Related Applications

The present application claims priority from U.S. patent application serial No. 15/195,789 entitled "substrate pre-treatment to reduce fill time in nanoimprint lithography" filed 2016, 6/28/2016, U.S. patent application serial No. 15/004,679 entitled "substrate pre-treatment to reduce fill time in nanoimprint lithography" filed 2016, 1/22/2016, and U.S. patent application serial No. 62/215,316 entitled "substrate pre-treatment to reduce fill time in nanoimprint lithography" filed 2015, 9/8/2015, each of which is incorporated herein by reference in its entirety.

Technical Field

The present invention relates to facilitating throughput in a nanoimprint lithography process by processing a nanoimprint lithography substrate to facilitate the development of an imprint resist on the substrate.

Background

Because the semiconductor processing industry strives for greater throughput while increasing the number of circuits per unit area, attention has been focused on the continued development of reliable, high-resolution patterning techniques. One such technique in use today is commonly referred to as imprint lithography. Imprint lithography methods are described in detail in numerous publications, such as U.S. patent application publication No. 2004/0065252 and U.S. patent nos. 6,936,194 and 8,349,241, all of which are incorporated herein by reference. Other areas of development in which imprint lithography has been used include biotechnology, optical technology and mechanical systems.

The imprint lithography techniques disclosed in each of the above patent documents include formation of a relief pattern (reliefpattern) in an imprint resist, and transfer of a pattern corresponding to the relief pattern to an underlying substrate. The patterning process uses a template spaced apart from a substrate and a polymerizable composition ("imprint resist") disposed between the template and the substrate. In some cases, the imprint resist is disposed on the substrate in the form of discrete, spaced-apart droplets. The droplets are spread out before the imprint resist is brought into contact with the template. After the imprint resist is contacted with the template, the resist is uniformly filled in the space between the substrate and the template, and then the imprint resist is cured to form a layer having a pattern conforming to the shape of the template surface. After curing, the template is separated from the patterned layer such that the template is spaced apart from the substrate.

The amount of processing in an imprint lithography process typically depends on various factors. When disposing the imprint resist on the substrate in the form of discrete, spaced-apart droplets, the throughput depends at least in part on the efficiency and uniformity of spreading of the droplets on the substrate. Spreading of the imprint resist may be inhibited by factors such as gas gaps between droplets and incomplete wetting of the substrate and/or template by the droplets.

Disclosure of Invention

In a first general aspect, a nanoimprint lithography method includes: disposing a pretreatment composition on a substrate to form a pretreatment coating on the substrate, disposing discrete portions of an imprint resist on the pretreatment coating, each discrete portion of the imprint resist covering a target area of the substrate. The pretreatment composition includes a polymerizable component and the imprint resist is a polymerizable composition. As each discrete portion of the imprint resist spreads beyond its target area, a composite polymerizable coating comprising a mixture of the pretreatment composition and the imprint resist is formed on the substrate. The composite polymeric coating is contacted with the nanoimprint lithography template and polymerized to produce a composite polymeric layer on the substrate. The interfacial energy between the pretreatment composition and air exceeds the interfacial energy between the imprint resist and air or between at least one component of the imprint resist and air.

A second general aspect includes a nanoimprint lithography stack formed by the method of the first aspect.

A third general aspect includes manufacturing an apparatus by the method of the first aspect. The apparatus may be a treated substrate, an optical component, or a quartz mold replica.

A fourth general aspect includes the apparatus of the third aspect.

In a fifth general aspect, a nanoimprint lithography kit includes a pretreatment composition and an imprint resist. The pretreatment composition includes a polymerizable component, the imprint resist is a polymerizable composition, and an interfacial energy between the pretreatment composition and air exceeds an interfacial energy between the imprint resist and air or between at least one component of the imprint resist and air.

In a sixth general aspect, a method of pre-treating a nanoimprint lithography substrate includes: coating a substrate with a pretreatment composition, and disposing discrete portions of an imprint resist on the pretreatment composition. The pretreatment composition includes a polymerizable component. An imprint resist disposed on a pretreatment composition in discrete portions spreads out more rapidly than the same imprint resist disposed on the same substrate in the absence of the pretreatment composition. After a defined period of time between disposing the discrete portions of the imprint resist on the pretreatment composition and contacting the imprint resist with the nanoimprint lithography template, the imprint resist is contacted with the nanoimprint lithography template. The volume of interstitial gaps between discrete portions of imprint resist disposed on the pretreatment composition when the imprint resist is in contact with the nanoimprint lithography template is less than interstitial gaps (interstitial void) between identical imprint resists disposed on a substrate in the absence of the pretreatment composition after a defined period of time has elapsed after the discrete portions of imprint resist are disposed on the substrate in the absence of the pretreatment composition.

In a seventh general aspect, a nanoimprint lithography stack includes a nanoimprint lithography substrate and a composite polymer layer formed on a surface of the nanoimprint lithography substrate. The composite polymer layer is non-uniform in chemical composition and includes a plurality of central regions separated by boundaries. The chemical composition of the composite polymer layer at the boundary is different from the chemical composition of the composite polymer layer inside the central region. In some cases, the nanoimprint lithography substrate includes an adhesion layer, and the composite polymer layer is formed on a surface of the adhesion layer. In some cases, the central region and the boundary of the polymer layer are formed from a non-uniform mixture of the pretreatment composition and the imprint resist.

Implementations of the various general aspects described above may include one or more of the following features, or may be formed by methods or components including one or more of the following features.

Disposing the pretreatment composition on the nanoimprint lithography substrate can be accomplished by spin coating the pretreatment composition on the nanoimprint lithography substrate. In some cases, the nanoimprint lithography substrate includes an adhesion layer, and disposing the pretreatment composition on the nanoimprint lithography substrate includes disposing the pretreatment composition on the adhesion layer.

Disposing the discrete portions of imprint resist on the pretreatment coating can include dispensing droplets of imprint resist on the pretreatment coating. In some cases, a discrete portion of the imprint resist contacts at least one other discrete portion of the imprint resist, forming a boundary between the two discrete portions before the composite polymeric coating contacts the nanoimprint lithography template. When the composite polymeric coating is in contact with the nanoimprint lithography template, each discrete portion of the imprint resist may be separated from at least one other discrete portion of the imprint resist via the pretreatment composition. In some cases, the composite coating is a homogeneous mixture of the pretreatment composition and the imprint resist.

Polymerizing the composite polymeric coating to provide the composite polymeric layer may include covalently bonding a component of the pretreatment composition to a component of the imprint resist. The chemical composition of the composite polymer layer may be non-uniform. The nanoimprint lithography template may be separate from the composite polymer layer.

In some cases, the difference between the interfacial energy between the pretreatment composition and air and the interfacial energy between the imprint resist and air is in a range of 0.5mN/m to 25mN/m, 0.5mN/m to 15mN/m, or 0.5mN/m to 7 mN/m. In some cases, the interfacial energy between the imprint resist and air is in a range of 20mN/m to 60mN/m, 28mN/m to 40mN/m, or 32mN/m to 35 mN/m. In still other cases, the interfacial energy between the pretreatment composition and air is in the range of 30mN/m to 45 mN/m. The viscosity of the pretreatment composition at 23 ℃ is typically in the range of 1cP to 200cP, 1cP to 100cP, or 1cP to 50 cP; the viscosity of the imprint resist at 23 ℃ is typically in the range of 1cP to 50cP, 1cP to 25cP, or 5cP to 15 cP.

The pretreatment composition can include a monomer. In some cases, the pretreatment composition includes, consists essentially of, or is a single monomer. In some cases, the pretreatment composition includes two or more monomers (e.g., monofunctional, difunctional, or multifunctional acrylate monomers). The pretreatment composition may include propoxylated (3) trimethylolpropane triacrylate, dipentaerythritol pentaacrylate, trimethylolpropane ethoxylate triacrylate, 1, 12-dodecanediol diacrylate, poly (ethylene glycol) diacrylate, tetraethyleneglycol diacrylate, 1, 3-adamantanediol diacrylate, nonanediol diacrylate, m-xylylene diacrylate, tricyclodecane dimethanol diacrylate, or any combination thereof. The pretreatment composition can include 1, 12-dodecanediol diacrylate, tricyclodecane dimethanol diacrylate, or combinations thereof; tetraethylene glycol diacrylate, tricyclodecane dimethanol diacrylate, or combinations thereof; 20 to 40 wt% of 1, 12-dodecanediol diacrylate and 60 to 80 wt% of tricyclodecane dimethanol diacrylate; or about 30 weight percent 1, 12-dodecanediol diacrylate and about 70 weight percent tricyclodecane dimethanol diacrylate. In some cases, the pretreatment composition does not contain a polymerization initiator.

Imprinting the resist may include: 0 wt% to 80 wt%, 20 wt% to 80 wt%, or 40 wt% to 80 wt% of one or more monofunctional acrylates; 20 to 98 wt% of one or more di-or multifunctional acrylates; 1 to 10 wt% of one or more photoinitiators; and 1 to 10 wt% of one or more surfactants. In some cases, the imprint resist includes 90 wt% to 98 wt% of one or more di-or multifunctional acrylates, and is substantially free of mono-functional acrylates. In some cases, the imprint resist includes one or more monofunctional acrylates and 20 wt% to 75 wt% of one or more difunctional or multifunctional acrylates.

The polymerizable components of the pretreatment composition and the polymerizable components of the imprint resist may react during polymerization of the composite polymerizable coating to form covalent bonds. The pretreatment composition and the imprint resist may each include monomers having a common functional group (e.g., an acrylate group).

The details of one or more implementations of the subject matter described in this specification are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims.

Drawings

FIG. 1 depicts a simplified side view of a lithography system.

FIG. 2 depicts a simplified side view of the substrate shown in FIG. 1 with a patterned layer formed on the substrate.

Fig. 3A-3D depict spreading interactions between droplets of a second liquid on a layer of a first liquid.

FIG. 4 is a flow chart describing a method of facilitating nanoimprint lithography throughput.

Fig. 5A depicts a substrate. Fig. 5B depicts a pretreatment coating disposed on a substrate.

FIGS. 6A-6D depict the formation of a composite coating from droplets of an imprint resist disposed on a substrate having a pretreatment coating.

FIGS. 7A-7D depict cross-sectional views along the lines w-w, x-x, y-y, and z-z of FIGS. 6A-6D, respectively.

Fig. 8A and 8B depict cross-sectional views of a pretreatment coating on a substrate by droplet replacement.

Figures 9A-9C depict cross-sectional views of a template and resulting nanoimprint lithography stack in contact with a uniform composite coating.

Figures 10A-10C depict cross-sectional views of a template and resulting nanoimprint lithography stack in contact with a non-uniform composite coating.

Fig. 11 is an image corresponding to comparative example 1 after development of droplets of imprint resist on the adhesion layer of a substrate without pretreatment coating.

Fig. 12 is an image of a drop of imprint resist as described in example 1 after development on the pretreatment coating.

Fig. 13 is an image of a drop of imprint resist as described in example 2 after development on the pretreatment coating.

Fig. 14 is an image of a drop of imprint resist as described in example 3 after development on the pretreatment coating.

FIG. 15 shows defect density as a function of pre-open time for an imprint resist and pretreatment composition of example 2.

Figure 16 shows droplet diameter versus development time of pretreatment composition.

Figure 17A shows viscosity as a function of fractional composition (fractional composition) of one component of a two-component pretreatment composition. Fig. 17B shows droplet diameter versus time for each ratio of components in a two-component pretreatment composition. Fig. 17C shows the surface tension of the two-part pretreatment composition versus the fraction of one component in the two-part pretreatment composition.

Detailed Description

FIG. 1 depicts an imprint lithography system 100 of the type used to form a relief pattern on a substrate 102. The substrate 102 may include a base (base) and an adhesive layer adhered to the base. The substrate 102 may be coupled to a substrate chuck 104. As shown, the substrate chuck 104 is a vacuum chuck. However, the substrate chuck 104 may be any chuck including, but not limited to, vacuum, nail, groove, and/or electromagnetic, among others. An exemplary cartridge is described in U.S. Pat. No. 6,873,087, which is incorporated herein by reference. The substrate 102 and substrate chuck 104 may be further supported by a pedestal 106. The stage 106 may provide movement about the x-, y-, and z-axes. The pedestal 106, substrate 102, and substrate chuck 104 may also be located on a base.

Spaced apart from the substrate 102 is a stencil 108. The template 108 generally includes a rectangular or square mesa (mesa)110 that is spaced a distance from the template surface toward the substrate 102. The surface of the mesa 110 may be patterned. In some cases, the mesa 110 is referred to as a mold 110 or mask 110. Template 108, mold 110, or both may be formed from materials including, but not limited to: fumed silica, quartz, silicon nitride, organic polymers, siloxane polymers, borosilicate glass, fluorocarbon polymers, metals (e.g., chromium, tantalum), hardened sapphire, or the like, or combinations thereof. As shown, the patterning of the surface 112 includes features defined by a plurality of spaced-apart recesses 114 and protrusions 116, although embodiments are not limited to such a configuration. The patterning of the surface 112 may define any original pattern that forms the basis of the pattern to be formed on the substrate 102.

Template 108 is connected to chuck 118. The chuck 118 is typically configured as, but not limited to, a vacuum, nail, groove, electromagnetic, or other similar chuck type. Exemplary chucks are further described in U.S. Pat. No. 6,873,087, which is incorporated herein by reference. Further, the chuck 118 may be coupled to the imprint head 120 such that the chuck 118 and/or the imprint head 120 may be configured to facilitate movement of the template 108.

The system 100 may further include a fluid distribution system 122. The fluid dispensing system 122 can be used to deposit an imprint resist 124 on the substrate 102. The imprint resist 124 may be dispensed on the substrate 102 using techniques such as drop dispensing, spin coating, dip coating, Chemical Vapor Deposition (CVD), Physical Vapor Deposition (PVD), thin film deposition, or thick film deposition. In the drop dispensing method, as depicted in FIG. 1, the imprint resist 124 is disposed on the substrate 102 in the form of discrete, spaced-apart drops.

The system 100 may further include an energy source 126 connected to the direct energy along the line path 128. The imprint head 120 and stage 106 may be configured to position the template 108 and substrate 102 in superimposition with the path 128. The system 100 may be conditioned by a processor 130 coupled to the pedestal 106, the imprint head 120, the fluid dispensing system 122, and/or the source 126, and may run on a computer readable program stored in a memory 132.

Imprint head 120 may apply a force to template 108 such that mold 110 contacts imprint resist 124. After filling the desired volume with the imprint resist 124, the source 126 generates energy (e.g., electromagnetic radiation or thermal energy), cures (e.g., polymerizes and/or crosslinks) the imprint resist 124, follows the shape of the surface 134 of the substrate 102, and patterns the surface 112. After the imprint resist 124 is cured to obtain a polymer layer on the substrate 102, the mold 110 is separated from the polymer layer.

Figure 2 depicts a nanoimprint lithography stack 200 formed by curing the imprint resist 124 to result in a patterned polymer layer 202 on the substrate 102. Patterned layer 202 may include remaining layer 204 and a plurality of features as shown by protrusions 206 and recesses 208, where protrusions 206 have a thickness t₁And the remaining layer 204 has a thickness t₂. In nanoimprint lithography, the length of one or more of the protrusions 206, recesses 208, or both, parallel to the substrate 102 is less than 100nm, less than 50nm, or less than 25 nm. In some cases, the length of one or more of the protrusions 206, recesses 208, or both is between 1nm and 25nm or between 1nm and 10 nm.

The above systems and methods may be used in imprint lithography methods and systems such as those described in U.S. patent nos. 6,932,934; 7,077,992, respectively; 7,197,396; and 7,396,475, all of which are incorporated herein by reference.

For drop-on-demand or drop-dispense nanoimprint lithography processes, in which the imprint resist 124 is disposed on the substrate 102 as discrete portions ("drops") as depicted in fig. 1, the drops of imprint resist are typically spread out on the substrate 102 before and after the mold 110 contacts the imprint resist. If the spread of the droplets of imprint resist 124 is insufficient to cover the substrate 102 or fill the recesses 114 of the mold 110, a polymer layer 202 having defects in the form of voids may be formed. Thus, drop-on-demand nanoimprint lithography methods typically include a delay between the start of dispensing of a drop of imprint resist 124 and the start of movement of mold 110 toward the imprint resist on substrate 102, and subsequent filling of the space between the substrate and the template. As such, the throughput of automated nanoimprint lithography processes is typically limited by the speed at which the imprint resist on the substrate is spread out and the speed at which the template is filled. Thus, the throughput of drop-on-demand or drop-dispense nanoimprint lithography processes can be improved by reducing the "fill time" (i.e., the time required to completely fill the space between the template and the substrate so that no voids are present).

One way to reduce the filling time is to increase the spreading speed of the droplets of imprint resist and the coverage of the substrate with imprint resist before the movement of the mold towards the substrate is started. Increasing the coverage of the substrate reduces the volume of interstitial gaps between droplets of imprint resist, thereby reducing the amount of gas trapped in the interstitial gaps when the imprint resist is in contact with the mold and reducing the number and severity of defects in the resulting patterned layer. As described herein, the spread rate of the imprint resist and the uniformity of the coverage of the substrate may be improved by pretreating the substrate with a liquid that promotes rapid and uniform spreading of discrete portions of the imprint resist and polymerization with the imprint resist during formation of the patterned layer, so as to reduce the amount of gas trapped in interstitial gaps when the imprint resist is in contact with the mold and the number and severity of defects in the resulting patterned layer.

The spreading of the discrete portions of the second liquid over the first liquid can be understood with reference to fig. 3A-3D. Fig. 3A-3D depict a first liquid 300 and a second liquid 302 on a substrate 304 and in contact with a gas 306 (e.g., air, an inert gas such as helium or nitrogen, or a combination of inert gases). The first liquid 300 is present on the substrate 304 in the form of a coating film or layer (used interchangeably herein). In some cases, the first liquid 300 is present as a layer having a thickness of a few nanometers (e.g., between 1nm and 15nm, or between 5nm and 10 nm). The second liquid 302 is present in the form of discrete portions ("droplets"). The properties of the first liquid 300 and the second liquid 302 may vary with respect to each other. For example, in some cases, the first liquid 300 may be more viscous and thicker than the second liquid 302.

The interfacial energy, or surface tension, between the second liquid 302 and the first liquid 300 is denoted γ_L1L2. The interfacial energy between the first liquid 300 and the gas 306 is denoted as γ_L1G. The interfacial energy between the second liquid 302 and the gas 306 is denoted as γ_L2G. The interfacial energy between the first liquid 300 and the substrate 304 is denoted as γ_SL1. The interfacial energy between the second liquid 302 and the substrate 304 is denoted as γ_SL2。

Fig. 3A depicts the second liquid 302 as droplets disposed on the first liquid 300. The second liquid 302 does not deform the first liquid 300 and does not touch the substrate 304. As shown, the first liquid 300 and the second liquid 302 are not intermixed, and the interface between the first liquid and the second liquid is described as being flat. At equilibrium, the contact angle of the second liquid 302 on the first liquid 300 is θ, which is related to the interfacial energy γ by Young's equation_L1G、γ_L2GAnd gamma_L1L2And (4) correlating.

γ_L1G＝γ_L1L2+γ_L2G·cos(θ) (1)

If gamma is_L1G≥γ_L1L2+γ_L2G(2)，

Then θ is 0 ° and the second liquid 302 is completely spread over the first liquid 300. If the liquid is miscible, after a certain time has elapsed,

γ_L1L2＝0 (3)。

in this case, the conditions for the complete development of the second liquid 302 on the first liquid 300 are:

γ_L1G≥γ_L2G(4)。

for a thin film of the first liquid 300 and small droplets of the second liquid 302, intermixing may be limited by the diffusion process. Thus, for the second liquid 302 to spread on the first liquid 300, the inequality (2) is more suitable for the initial stage of spreading when the second liquid 302 is disposed on the first liquid 300 in the form of droplets.

Fig. 3B depicts the formation of a contact angle of a drop of the second liquid 302 when the bottom layer (undercovering layer) of the first liquid 300 is thick. In this case, the droplet does not touch the substrate 304. The droplets of the second liquid 302 and the layer of the first liquid 300 intersect at angles α, β, and θ, wherein

α+β+θ＝2π (5)。

There are three conditions of force balance along each interface:

γ_L2G+γ_L1L2·cos(θ)+γ_L1G·cos(α)＝0 (6)

γ_L2G·cos(θ)+γ_L1L2+γ_L1G·cos(β)＝0 (7)

γ_L2G·cos(α)+γ_L1L2·cos(β)+γ_L1G＝0 (8)。

if the first liquid 300 and the second liquid 302 are miscible, then

γ_L1L2＝0 (9)，

And equations (6) - (8) become:

γ_L2G+γ_L1G·cos(α)＝0 (10)

γ_L2G·cos(θ)+γ_L1G·cos(β)＝0 (11)

γ_L2G·cos(α)+γ_L1G＝0 (12)

equations (10) and (12) yield:

cos²(α)＝1 (13)，

and is

α＝0,π (14)。

When the second liquid 302 wets the first liquid 300,

α＝π (15)

γ_L2G＝γ_L1G(16)

and equation (11) yields:

cos(θ)+cos(β)＝0 (17)

combining this result with equations (5) and (15) yields:

θ＝0 (18)

β＝π (19)

thus, equations (15), (18), and (19) yield solutions for angles α, β, and θ.

When in use

γ_L1G≥γ_L2G(20) When the temperature of the water is higher than the set temperature,

there is no equilibrium between the interfaces. Even for α ═ pi, equation (12) becomes an inequality, and the second liquid 302 continuously spreads over the first liquid 300.

FIG. 3C depicts a more complex geometry for the droplets of the second liquid 302 to touch the substrate 304 while also having an interface with the first liquid 300. the interfacial area (defined by angles α, β, and θ) between the first liquid 300, the second liquid 302, and the gas 306 must be considered₁Defined by angle θ) and the interfacial area (defined by angle θ) between first liquid 300, second liquid 302, and substrate 304₂Defined) to determine the spreading behavior of the second liquid on the first liquid.

The interfacial area between first liquid 300, second liquid 302, and gas 306 is governed by equations (6) - (8). Since the first liquid 300 and the second liquid 302 are miscible, it is possible to obtain a liquid mixture

γ_L1L2＝0 (21)。

The solution of the angle α is given by equation (14). In this case, make

α＝0 (22)，

And is

θ₁＝π (23)，

β＝π (24)。

When in use

γ_L1G≥γ_L2G(25) When the temperature of the water is higher than the set temperature,

there is no equilibrium between the droplets of the second liquid 302 and the first liquid 300, and the droplets continue to spread along the interface between the second liquid and the gas until limited by other physical constraints (e.g., volume conservation and intermixing).

For the interfacial area between the first liquid 300, the second liquid 302, and the substrate 304, an equation similar to equation (1) should be considered:

γ_SL1＝γ_SL2+γ_L1L2·cos(θ₂) (26)。

if it is not

γ_SL1≥γ_SL2+γ_L1L2(27)，

The droplet is completely spread out and θ₂＝0。

Again, with respect to miscible liquids, the second term γ _L1L20, and the inequality (27) is simplified to:

γ_SL1≥γ_SL2(28)。

when considering the energy before and after spreading, the conditions for the combination of droplet spreading are expressed as:

γ_L1G+γ_SL1≥γ_L2G+γ_SL2(29)。

there should be an aggressively favorable transition (i.e., a transition that minimizes the energy of the system).

Different relationships between the four terms in the inequality (29) will determine the drop spread characteristics. If inequality (25) is valid and inequality (28) is not, the drop of second liquid 302 may initially spread along the surface of first liquid 300. Alternatively, the droplet may begin to spread along the liquid-solid interface, provided that inequality (28) holds and inequality (25) does not hold. Finally, the first liquid 300 and the second liquid 302 will intermix, thus introducing more complexity.

FIG. 3D depicts the geometry of a droplet of the second liquid 302 touching the substrate 304 while having an interface with the first liquid 300. As shown in FIG. 3D, there are two interface regions of interest on each side of the droplet of the second liquid 302. the first interface region is defined by angles α, β, and θ₁A first liquid 300, a second liquid 302, and a gas 306 are shown where they meet. The second interface region of interest is defined by the angle θ₂A first liquid 300, a second liquid 302, and a substrate 304 are shown where they meet. Here, when the surface tension of the interface between the second liquid 302 and the substrate 304 exceeds the surface tension (γ) of the interface between the first liquid 300 and the substrate_SL2≥γ_SL1) When, as the droplet spreads out, [ theta ]₁Close to 0 deg., theta₂Approximately 180. That is, the droplets of the second liquid 302 spread along the interface between the first liquid 300 and the second liquid, and do not spread along the interface between the second liquid and the substrate 304.

Equations (6) - (8) apply for the interface between first liquid 300, second liquid 302, and gas 306. The first liquid 300 and the second liquid 302 are miscible, so

γ_L1L2＝0 (30)。

The solution of the angle α is given by equation (14). For the

α＝π (31)，

Equation (11) yields

cos(θ₁)+cos(β)＝0 (32)，

And is

θ₁＝0 (33)

β＝π (34)。

When in use

γ_L1G≥γ_L2G(35) When the temperature of the water is higher than the set temperature,

For the interfacial region between the second liquid 302 and the substrate 304,

γ_SL1＝γ_SL2+γ_L1L2·cos(θ₂) (36)

if it is not

γ_SL1≤γ_SL2(38)，

And the liquids being miscible, i.e.

γ_L1L2→0 (39)

-∞≤_cos(θ2)≤-1 (40)，

Angle theta₂Approaching 180 deg., and then becoming ambiguous. That is, the second liquid 302 has a tendency to contract along the substrate interface and expand along the interface between the first liquid 300 and the gas 306.

The spread of the second liquid 302 over the first liquid 300 together with the fully spread surface energy relationship can be summarized in three different cases. In the first case, the droplets of the second liquid 302 are disposed on the layer of the first liquid 300, and the droplets of the second liquid do not contact the substrate 304. The layer of the first liquid 300 may be thick or thin, and the first liquid 300 and the second liquid 302 are miscible. Under ideal conditions, when the surface energy of the first liquid 300 in the gas 306 is greater than or equal to the surface energy (γ) of the second liquid 302 in the gas_L1G≥γ_L2G) Full spreading of the droplets of the second liquid 302 occurs on the layer of the first liquid 300. In the second case, droplets of the second liquid 302 are disposed on the layer of the first liquid 300 while simultaneously touching and spreading on the substrate 304. The first and second liquids 302 are miscible. Under ideal conditions, when (i) the surface energy of the first liquid 300 in the gas is greater than or equal to the surface energy (γ) of the second liquid 302 in the gas_L1G≥γ_L2G) (ii) a (ii) The surface energy of the interface between the first liquid and the substrate 304 exceeds the surface energy (γ) of the interface between the second liquid and the substrate_SL1≥γ_SL2) Full deployment occurs. In the third case, droplets of the second liquid 302 are disposed on the layer of the first liquid 300 while touching the substrate 304. Spreading may occur along the interface between the second liquid 302 and the first liquid 300 or the interface between the second liquid and the substrate 304. The first and second liquids 302 are miscible. Under ideal conditions, the surface energy of the first liquid 300 in the gas is greater than or equal to the surface energy (γ) of the second liquid 302 in the gas_L1G≥γ_L2G) Or (ii) the surface energy of the interface between the first liquid and the substrate 304 exceeds the surface energy (γ) of the interface between the second liquid and the substrate_SL1≥γ_SL2) At the same time, when the sum of the surface energy of the first liquid 300 in the gas and the surface energy of the interface between the first liquid and the substrate 304 is largeIs equal to or greater than the sum of the surface energy of the second liquid 302 in the gas and the surface energy of the interface between the second liquid and the substrate (gamma)_L1G+γ_SL1≥γ_L2G+γ_SL2) Full deployment occurs. When the second liquid 302 comprises more than one component, the sum of the surface energy of the first liquid 300 in the gas and the surface energy of the interface between the first liquid and the substrate 304 is greater than or equal to the sum of the surface energy of the second liquid 302 in the gas and the surface energy of the interface between the second liquid and the substrate (γ [) while the surface energy of the first liquid 300 in the gas is greater than or equal to the surface energy of at least one of the components of the second liquid 302 in the gas, or (ii) the surface energy of the interface between the first liquid and the substrate 304 exceeds the surface energy of the interface between one component of the second liquid and the substrate_L1G+γ_SL1≥γ_L2G+γ_SL2) Full deployment may occur.

By pretreating the nanoimprint lithography substrate with a liquid pretreatment composition selected to have a surface energy greater than that of the imprint resist in an ambient atmosphere (e.g., air or an inert gas), the speed at which the imprint resist spreads on the substrate in an on-demand drop nanoimprint lithography process may be increased, and a more uniform thickness of the imprint resist on the substrate may be established prior to contact of the imprint resist with the template, thereby facilitating throughput in the nanoimprint lithography process. The substrate pretreatment method reduces dispense time by improving drop spreading and thus reducing interstitial gap volume between drops of imprint resist prior to imprinting. As used herein, "dispense time" generally refers to the time between a drop dispense and the template touching the drop. If the pretreatment composition includes a polymeric component that can be intermixed with the imprint resist, this can advantageously facilitate formation of the resulting polymer layer without the need for addition of undesirable components and can result in more uniform curing, thereby providing more uniform mechanical and etch properties.

FIG. 4 is a flow diagram illustrating a process 400 to facilitate throughput in drop-on-demand nanoimprint lithography. Process 400 includes

operation

402 and 410. In operation 402, a pretreatment composition is disposed on a nanoimprint lithography substrate to form a pretreatment coating on the substrate. In operation 404, discrete portions ("droplets") of imprint resist are disposed on the pretreatment coating, wherein each droplet covers a target area of the substrate. The pretreatment composition and the imprint resist are selected such that the interfacial energy between the pretreatment composition and air exceeds the interfacial energy between the imprint resist and air.

In operation 406, a composite polymeric coating ("composite coating") is formed on the substrate as each drop of imprint resist spreads beyond its target area. The composite coating includes a uniform or non-uniform mixture of the pretreatment composition and the imprint resist. In operation 408, the composite coating is brought into contact with a nanoimprint lithography template ("template") and spread out and fill all volumes between the template and the substrate; in operation 410, the composite coating is polymerized to produce a polymer layer on the substrate. After polymerization of the composite coating, the template is separated from the polymer layer, leaving a nanoimprint lithography stack. As used herein, a "nanoimprint lithography stack" generally refers to a substrate and a polymer layer adhered to the substrate, each or both of which may include one or more additional (e.g., intervening) layers. In one example, a substrate includes a base and an adhesive layer adhered to the base.

The surface energy of the imprint resist functions as a capillary between the template and the substrate during resist development. The pressure difference across the capillary meniscus that is formed is proportional to the surface energy of the liquid. The higher the surface energy, the greater the driving force for the liquid to unfold. Thus, higher surface energy imprint resists are typically preferred. The dynamics of resist droplet development while interacting with the pretreatment composition is dependent on the viscosity of both the imprint resist and the pretreatment composition. Imprint resists or pretreatment compositions with higher viscosity tend to slow droplet development dynamics and may, for example, slow down the imprinting process. The capillary pressure difference is proportional to the interfacial tension γ, inversely proportional to the effective radius r of the interface, and also depends on the wetting angle θ of the liquid on the surface of the capillary. Imprint resists with high surface tension and small contact angles are desirable for fast filling in nanoimprint lithography processes. The contact angle of the imprint resist on the surface of the nanoimprint lithography template is typically less than 90 °, less than 50 °, or less than 30 °.

In process 400, the pretreatment composition and imprint resist may include a mixture of components as described in, for example, U.S. patent No. 7,157,036 and U.S. patent No. 8,076,386; and Chou et al 1995, Imprint of sub-25nm vias and tresches in polymers (imprint of sub-25nm vias and trenches in polymers). Applied Physics Letters 67(21): 3114-; chou et al 1996, Nanoimprint lithography. Journal of Vacuum Science Technology B14 (6): 4129-4133; and Long et al 2007 Materials for step and flash print graphics

(stepped flash imprint lithography material). Journal of Materials Chemistry 17: 3575-. Suitable compositions include polymerizable monomers ("monomers"), crosslinkers, resins, photoinitiators, surfactants, or any combination thereof. The classes of monomers include acrylates, methacrylates, vinyl ethers, and epoxides, as well as their multifunctional derivatives. In some cases, the pretreatment composition, the imprint resist, or both are substantially free of silicon. In other cases, the pretreatment composition, the imprint resist, or both are silicon-containing. Silicon-containing monomers include, for example, siloxanes and disiloxanes. The resin may be silicon containing (e.g., silsesquioxanes) and non-silicon containing (e.g., novolac resins). The pretreatment composition, the imprint resist, or both may also include one or more polymerization initiators or free radical generators. The kind of the polymerization initiator includes, for example, photoinitiators (e.g., acyloins, xanthones, and benzophenones), photoacid generators (e.g., sulfonates and onium salts), and photobase generators (e.g., O-nitrobenzylcarbamates, oxime polyurethanes, and O-acyl oximes).

Suitable monomers include monofunctional, difunctional, or multifunctional acrylates, methacrylates, vinyl ethers, and epoxides wherein mono-, di-, and poly-each means one, two, or more than three of the indicated functional groups. Some or all of the monomers may be fluorinated (e.g., perfluorinated). In the case of acrylates, for example, the pretreatment agent, the imprint resist, or both may include one or more monofunctional acrylates, one or more difunctional acrylates, one or more multifunctional acrylates, or a combination thereof.

Examples of suitable monofunctional acrylates include isobornyl acrylate, 3, 5-trimethylcyclohexyl acrylate, dicyclopentenyl acrylate, benzyl acrylate, 1-naphthyl acrylate, 4-cyanobenzyl acrylate, pentafluorobenzyl acrylate, 2-phenylethyl acrylate, phenyl acrylate, 2-ethyl-2-methyl-1, 3-dioxolan-4-yl) methyl acrylate, n-hexyl acrylate, 4-tert-butylcyclohexyl acrylate, methoxypolyethylene glycol (350) monoacrylate, and methoxypolyethylene glycol (550) monoacrylate.

Examples of suitable diacrylates include ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate (e.g., Mn, average 575), 1, 2-propanediol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate, 1, 3-propanediol diacrylate, 1, 4-butanediol diacrylate, 2-butene-1,4-diacrylate (2-butene-1,4-diacrylate), 1, 3-butanediol diacrylate, 3-methyl-1, 3-butanediol diacrylate, 1, 5-pentanediol diacrylate, 1, 6-hexanediol diacrylate, 1H,6H, 6H-perfluoro-1, 6-hexanediol diacrylate, 1, 9-nonanediol diacrylate, 1, 10-decanediol diacrylate, 1, 12-dodecanediol diacrylate, neopentyl glycol diacrylate, cyclohexanedimethanol diacrylate, tricyclodecane dimethanol diacrylate, bisphenol A diacrylate, ethoxylated bisphenol A diacrylate, m-xylylene diacrylate, ethoxylated (3) bisphenol A diacrylate, ethoxylated (4) bisphenol A diacrylate, ethoxylated (10) bisphenol A diacrylate,Dicyclopentanyl diacrylate, 1, 2-adamantanediol diacrylate, 2, 4-diethylpentane-1, 5-diol diacrylate, poly (ethylene glycol) (400) diacrylate, poly (ethylene glycol) (300) diacrylate, 1, 6-hexanediol (EO)₂Diacrylate, 1, 6-hexanediol (EO)₅Diacrylates and alkoxylated aliphatic diacrylates.

Examples of suitable multifunctional acrylates include trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylates (e.g., propoxylated (3) trimethylolpropane triacrylate, propoxylated (6) trimethylolpropane triacrylate), trimethylolpropane ethoxylate triacrylates (e.g., n to 1.3, 3, 5), ditrimethylolpropane tetraacrylate, propoxylated glyceryl triacrylates (e.g., propoxylated (3) glyceryl triacrylate), tris (2-hydroxyethyl) isocyanurate triacrylate, pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, tripentaerythritol octaacrylate.

Examples of suitable crosslinking agents include difunctional acrylates and multifunctional acrylates, such as those described herein.

The photoinitiator is preferably a free radical generator. Examples of suitable free radical generators include, but are not limited to, 2,4, 5-triarylimidazole dimers optionally having substituents, such as 2- (o-chlorophenyl) -4, 5-diphenylimidazole dimer, 2- (o-chlorophenyl) -4, 5-bis (methoxyphenyl) imidazole dimer, 2- (o-fluorophenyl) -4, 5-diphenylimidazole dimer, and 2- (o-or p-methoxyphenyl) -4, 5-diphenylimidazole dimer; benzophenone derivatives such as benzophenone, N '-tetramethyl-4, 4' -diaminobenzophenone (michler's ketone), N' -tetraethyl-4, 4 '-diaminobenzophenone, 4-methoxy-4' -dimethylaminobenzophenone, 4-chlorobenzophenone, 4 '-dimethoxybenzophenone, and 4,4' -diaminobenzophenone; α -amino aromatic ketone derivatives such as 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1, 2-methyl-1- [4- (methylthio) phenyl ] -2-morpholino-propan-1-one; quinones such as 2-ethylanthraquinone, phenanthrenequinone, 2-tert-butylanthraquinone, octamethylanthraquinone, 1, 2-benzoanthraquinone, 2, 3-benzoanthraquinone, 2-phenylanthraquinone, 2, 3-diphenylanthraquinone, 1-chloroanthraquinone, 2-methylanthraquinone, 1, 4-naphthoquinone, 9, 10-phenanthrenequinone, 2-methyl-1, 4-naphthoquinone, and 2, 3-dimethylanthraquinone; benzoin ether derivatives such as benzoin methyl ether, benzoin ethyl ether, and benzoin phenyl ether; benzoin derivatives such as benzoin, methylbenzoin, ethylbenzoin and propylbenzoin; benzyl derivatives, such as benzyl dimethyl ketal; acridine derivatives, such as 9-phenylacridine and 1, 7-bis (9,9' -acridinyl) heptane; n-phenylglycine derivatives, such as N-phenylglycine; acetophenone derivatives such as acetophenone, 3-methylacetophenone, acetophenone benzyl ketal, 1-hydroxycyclohexyl phenyl ketone, and 2, 2-dimethoxy-2-phenylacetophenone; thioxanthone derivatives such as thioxanthone, diethylthioxanthone, 2-isopropylthioxanthone, and 2-chlorothioxanthone; acylphosphine oxide derivatives such as 2,4, 6-trimethylbenzoyldiphenylphosphine oxide, bis (2,4, 6-trimethylbenzoyl) phenylphosphine oxide, and bis (2, 6-dimethoxybenzoyl) -2,4, 4-trimethylpentylphosphine oxide; oxime ester derivatives, such as 1, 2-octanedione, 1- [4- (phenylthio) -,2- (O-benzoyloxime) ], ethanone, and 1- [ 9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl ] -,1- (O-acetyloxime); and xanthone, fluorenone, benzaldehyde, fluorene, anthraquinone, triphenylamine, carbazole, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, and 2-hydroxy-2-methyl-1-phenylpropan-1-one.

Examples of commercially available products of free radical generators include, but are not limited to,

IRGACURE

184, 250, 270, 290, 369, 379, 651, 500, 754, 819, 907, 784, 1173, 2022, 2100, 2959, 4265, BP, MBF, OXE01, OXE02, PAG121, PAG203, CGI-1700, -1750, -1850, CG24-61, CG2461, DAROCUR 1116, 1173, LUCIRIN TPO, TPO-L, LR8893, LR8953, LR8728, and LR8970, manufactured by BASF; and EBECRYL P36 manufactured by UCB.

An acylphosphine oxide-based polymerization initiator or an alkylphenone-based polymerization initiator is preferable. In the above-exemplified examples, the acylphosphine oxide-based polymerization initiator is an acylphosphine oxide compound such as 2,4, 6-trimethylbenzoyldiphenylphosphine oxide, bis (2,4, 6-trimethylbenzoyl) phenylphosphine oxide, and bis (2, 6-dimethoxybenzoyl) -2,4, 4-trimethylpentylphosphine oxide. In the above-listed examples, the alkylphenone-based polymerization initiator is a benzoin ether derivative such as benzoin methyl ether, benzoin ethyl ether, and benzoin phenyl ether; benzoin derivatives such as benzoin, methylbenzoin, ethylbenzoin, and propylbenzoin; benzyl derivatives, such as benzyl dimethyl ketal; acetophenone derivatives such as acetophenone, 3-methylacetophenone, acetophenone benzyl ketal, 1-hydroxycyclohexyl phenyl ketone, and 2, 2-dimethoxy-2-phenylacetophenone; and α -amino aromatic ketone derivatives such as 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1, 2-methyl-1- [4- (methylthio) phenyl ] -2-morpholinopropan-1-one.

The content of the photoinitiator is 0.1 wt% or more and 50 wt% or less, preferably 0.1 wt% or more and 20 wt% or less, more preferably 1 wt% or more and 20 wt% or less, relative to the total weight of all components except the solvent component.

When the content of the photoinitiator is 0.1 wt% or more relative to the total weight excluding the solvent component, the curing speed of the curable composition can be accelerated. As a result, the reaction efficiency can be improved. When the content is 50 wt% or less with respect to the total weight excluding the solvent component, the resulting cured product may be a cured product (cured product) having a certain degree of mechanical strength.

Examples of suitable photoinitiators include IRGACURE 907, IRGACURE 4265, 651, 1173, 819, TPO, and TPO-L.

Surfactants may be applied to the patterned surface of the imprint lithography template, added to the imprint lithography resist, or both, to reduce the separation force between the cured resist (solidified resist) and the template, thereby reducing separation defects in the imprint pattern formed in the imprint lithography process and increasing the number of successive imprints that can be made using the imprint lithography template. Factors for selecting a release agent for an imprint resist include, for example, affinity for the surface, desired surface properties of the treated surface, and the lifetime of the release agent in the imprint resist. While some release agents form covalent bonds with the template, the fluorinated nonionic surfactants interact with the template surface via non-covalent interactions such as hydrogen bonds and van der waals interactions.

Examples of suitable surfactants include fluorinated and non-fluorinated surfactants. The fluorinated and non-fluorinated surfactants may be ionic or non-ionic surfactants. Suitable nonionic fluorinated surfactants include fluoroaliphatic polymeric esters, perfluoroether surfactants, fluorosurfactants of polyoxyethylene, fluorosurfactants of polyalkyl ethers, fluoroalkyl polyethers, and the like. Suitable non-ionic non-fluorinated surfactants include ethoxylated alcohols, ethoxylated alkylphenols, and polyethylene oxide-polypropylene oxide block copolymers.

Exemplary commercially available surfactant components include, but are not limited to, those manufactured by e.i. du Pont de Nemours and Company, wilmington, terawa

FSO and

FS-300; FC-4432 and FC-4430 manufactured by 3M, Inc. of Mepriwood, Minn.J.; manufactured by Pilot Chemical Company whose offices are located in Cincinnati, Ohio

FS-1700, FS-2000 and FS-2800; S-107B, manufactured by Chemguard, whose office is located in Mansfield, Texas; FTERGENT 222F, FTERGENT 250, FTERGENT 251 manufactured by NEOSchemical Chuo-ku, Kobe-shi, Japan; PolyFox PF-656, manufactured by OMNOVA Solutions Inc. of Akron, Ohio; pluronic L35, L42, L43, L44, L63, L64, etc., manufactured by BASF, whose offices are located in florem park, new jersey; brij 35, 58, 78, etc., manufactured by Croda inc, of edison, new jersey.

Further, the pretreatment composition and the imprint resist may include one or more non-polymerizable compounds according to various purposes, in addition to the above-described components, without impairing the effects of the present disclosure. Examples of such components include sensitizers, hydrogen donors, antioxidants, polymer components, and other additives.

The sensitizer is a compound appropriately added for the purpose of accelerating the polymerization reaction or improving the reaction conversion rate. Examples of suitable sensitizers include sensitizing dyes.

The sensitizing dye is a compound which is excited by absorbing light having a specific wavelength to interact with the photoinitiator as the component (B). As used herein, the interaction refers to energy transfer, electron transfer, or the like from the sensitizing dye in an excited state to the photoinitiator as component (B).

Specific examples of suitable sensitizing dyes include, but are not limited to, anthracene derivatives, anthraquinone derivatives, pyrene derivatives, perylene derivatives, carbazole derivatives, benzophenone derivatives, thioxanthone derivatives, xanthone derivatives, coumarin derivatives, phenothiazine derivatives, camphorquinone derivatives, acridine-based dyes, thiopyrylium salt-based dyes (thiopyrylium salt dyes), merocyanine-based dyes, quinoline-based dyes, styrylquinoline-based dyes, ketocoumarine-based dyes, thioxanthone-based dyes, xanthene-based dyes, oxonol-based dyes (oxonol dyes), cyanine-based dyes, rhodamine-based dyes, and pyrylium salt-based dyes.

One of these sensitizers may be used alone, or two or more of these sensitizers may be used as a mixture.

The hydrogen donor is a compound that reacts with an initiating radical generated by a photoinitiator as the component (B), or a radical at the growing end of the polymer to generate a radical of higher reactivity. When component (B) is one or more photo radical generators, it is preferred to add a hydrogen donor.

Specific examples of suitable hydrogen donors include, but are not limited to, amine compounds such as N-butylamine, di-N-butylamine, tri-N-butylamine, allylthiourea, s-benzylisothiouronium-p-toluenesulfinate, triethylamine, diethylaminoethyl methacrylate, triethylenetetramine, 4' -bis (dialkylamino) benzophenone, ethyl N, N-dimethylaminobenzoate, isoamyl N, N-dimethylaminobenzoate, amyl-4-dimethylaminobenzoate, triethanolamine, and N-phenylglycine; and mercapto compounds such as 2-mercapto-N-phenylbenzimidazole and mercaptopropionate.

One of these hydrogen donors may be used alone, or two or more of these hydrogen donors may be used as a mixture. In addition, the hydrogen donor may have a function as a sensitizer.

The content of these components (non-polymerizable compound) in the imprint resist is 0 wt% or more and 50 wt% or less, preferably 0.1 wt% or more and 50 wt% or less, more preferably 0.1 wt% or more and 20 wt% or less, relative to the total weight of all components except the solvent component.

Furthermore, the imprint resist may include one or more solvents as additional components. Preferred solvents include, but are not limited to, solvents having a boiling point of 80 ℃ or higher and 200 ℃ or lower at normal pressure. Solvents each having at least one of a hydroxyl group, an ether structure, an ester structure, or a ketone structure are more preferable.

Specific examples of suitable solvents include alcohol solvents such as propanol, isopropanol, and butanol; ether solvents such as ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, ethylene glycol monoethyl ether, ethylene glycol diethyl ether, ethylene glycol monobutyl ether and propylene glycol monomethyl ether; ester solvents such as butyl acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, and propylene glycol monomethyl ether acetate; and ketone solvents such as methyl isobutyl ketone, diisobutyl ketone, cyclohexanone, 2-heptanone, γ -butyrolactone and ethyl lactate. A single solvent or a mixed solvent selected from these solvents is preferable.

In some cases, the pretreatment composition may be combined with one or more solvents. In one example, where the pretreatment composition is applied via spin coating, the pretreatment composition is combined with one or more solvents to facilitate spreading on the substrate, after which substantially all of the solvent is evaporated to leave the pretreatment composition on the substrate.

Solvents suitable for combination with the pretreatment composition generally include those described with respect to imprint resists. For spin-coating application of the pretreatment composition, a single solvent or a mixed solvent selected from propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, cyclohexanone, 2-heptanone, γ -butyrolactone, and ethyl lactate is particularly preferable from the viewpoint of coating properties.

The content of the solvent component to be combined with the pretreatment composition can be appropriately adjusted by viscosity, coating property, film thickness of the formed cured layer, and the like, and is preferably 70 wt% or more, preferably 90 wt% or more, and further preferably 95 wt% or more with respect to the total amount of the pretreatment composition and the solvent. The greater the content of the solvent component, the thinner the film thickness of the pretreatment composition can be. If the content of the solvent component is 70 wt% or less of the solvent/pretreatment composition mixture, sufficient coating properties may not be obtained.

Although such solvents may be used in the imprint resist, it is preferred that the imprint resist should be substantially free of solvents. As used herein, the phrase "substantially free of solvent" means free of solvent other than that which it is not intended to contain, such as impurities. For example, the content of the solvent in the imprint resist according to the present embodiment is preferably 3 wt% or less, more preferably 1 wt% or less, with respect to the entire imprint resist. As used herein, the solvent refers to a solvent generally used in a curable composition or a photoresist. In other words, the solvents are not limited to their kinds as long as the solvents can dissolve and uniformly disperse the compounds used in the present invention without reacting with the compounds.

In some examples, the imprint resist includes 0 wt% to 80 wt% (e.g., 20 wt% to 80 wt%, or 40 wt% to 80 wt%) of one or more monofunctional acrylates; 90 wt% to 98 wt% of one or more di-or multifunctional acrylates (e.g., the imprint resist may be substantially free of mono-functional acrylates), or 20 wt% to 75 wt% of one or more di-or multifunctional acrylates (e.g., when one or more mono-functional acrylates are present); 1 to 10 wt.%One or more photoinitiators; and 1 to 10 wt% of one or more surfactants. In one example, the imprint resist includes about 40 wt% to about 50 wt% of one or more monofunctional acrylates, about 45 wt% to about 55 wt% of one or more difunctional acrylates, about 4 wt% to about 6 wt% of one or more photoinitiators, and about 3 wt% of a surfactant. In another example, the imprint resist includes about 44 wt% of one or more monofunctional acrylates, about 48 wt% of one or more difunctional acrylates, about 5 wt% of one or more photoinitiators, and about 3 wt% of a surfactant. In yet another example, the imprint resist includes about 10 wt% of a first monofunctional acrylate (e.g., isobornyl acrylate), about 34 wt% of a second monofunctional acrylate (e.g., benzyl acrylate), about 48 wt% of a difunctional acrylate (e.g., neopentyl glycol diacrylate), about 2 wt% of a first photoinitiator (e.g., IRGACURE TPO), about 3 wt% of a second photoinitiator (e.g., DAROCUR 4265), and about 3 wt% of a surfactant. Examples of suitable surfactants include X-R- (OCH)₂CH₂)_nOH, wherein R is alkyl, aryl, or poly (propylene glycol), X is H or- (OCH)₂CH₂)_nOH, and n is an integer (e.g., 2 to 20, 5 to 15, or 10 to 12) (e.g., X ═ OCH₂CH₂)_nOH, R ═ poly (propylene glycol), and n ═ 10 to 12); a fluorosurfactant, wherein X ═ perfluorinated alkyl or perfluorinated ether, or a combination thereof. The viscosity of the imprint resist at 23 ℃ is typically in the range of 1cP to 50cP, 1cP to 25cP, or 5cP to 15 cP. The interfacial energy between the imprint resist and air is typically in the range of 20 to 60, 28 to 40, or 32 to 35 mN/m. Viscosity and interfacial energy were evaluated as described in the examples herein.

In one example, the pretreatment composition comprises 0 wt% to 80 wt% (e.g., 20 wt% to 80 wt%, or 40 wt% to 80 wt%) of one or more monofunctional acrylates; from 90 wt% to 100 wt% of one or more di-or multifunctional acrylates (e.g., the pretreatment composition is substantially free of mono-functional acrylates), or from 20 wt% to 75 wt% of one or more di-or multifunctional acrylates (e.g., when one or more mono-functional acrylates are present); 0 to 10 wt% of one or more photoinitiators; and 0 wt% to 10 wt% of one or more surfactants.

The pretreatment composition typically has a low vapor pressure such that it remains present as a film on the substrate until polymerization of the composite coating, hi one example, the vapor pressure of the pretreatment composition at 25 ℃ is less than 1 × 10^-4mmHg. The pretreatment composition also typically has a low viscosity to facilitate rapid spreading of the pretreatment composition on the substrate. In one example, the viscosity of the pretreatment composition at 23 ℃ is typically in the range of 1cP to 200cP, 1cP to 100cP, or 1cP to 50 cP. The interfacial energy between the pretreatment composition and air is typically between 30mN/m and 45 mN/m. The pretreatment composition is typically selected to be chemically stable so that no decomposition occurs during use.

It is preferred that the pretreatment composition and the imprint resist should contain impurities in the smallest possible amount. As used herein, impurities refer to any other component in addition to the components described above. Thus, the pretreatment composition and the imprint resist are preferably obtained by a purification process. Such purification process is preferably filtration using a filter or the like. For filtration using a filter, specifically, it is preferable that the above-described respective components and optional additive components should be mixed and then filtered through a filter having a pore size of, for example, 0.001 μm or more and 5.0 μm or less. For filtration using a filter, it is more preferable that the filtration should be performed in multiple stages or repeated multiple times. In addition, the filtrate may be filtered again. Multiple filters of different pore sizes may be used in the filtration. One or more filters made of polyethylene resin, polypropylene resin, fluorine resin, nylon resin, or the like may be used in the filtration, although the filter is not limited thereto. Impurities such as particles mixed in the composition can be removed by such purification process. This can prevent impurities such as particles from causing pattern defects resulting from inadvertent unevenness in a cured film obtained by curing the curable composition.

In the case where the pretreatment composition and the imprint resist are used for producing a semiconductor integrated circuit, it is preferable to avoid mixing of impurities containing metal atoms (metal impurities) in the curable composition as much as possible for preventing the handling of the product from being inhibited. In such a case, the concentration of the metal impurities contained in the curable composition is preferably 10ppm or less, and more preferably 100ppb or less.

The pretreatment composition can be a single polymerizable component (e.g., a monomer such as a monofunctional acrylate, a difunctional acrylate, or a multifunctional acrylate), a mixture of two or more polymerizable components (e.g., a mixture of two or more monomers), or a mixture of one or more polymerizable components and one or more other components (e.g., a mixture of monomers; and a mixture of two or more monomers with a surfactant, a photoinitiator, or both; and the like). In some examples, the pretreatment composition comprises trimethylolpropane triacrylate, trimethylolpropane ethoxylate triacrylate, 1, 12-dodecanediol diacrylate, poly (ethylene glycol) diacrylate, tetraethylene glycol diacrylate, 1, 3-adamantanediol diacrylate, nonanediol diacrylate, meta-diphenylmethylene diacrylate, dicyclopentanyl diacrylate, or any combination thereof.

The mixture of polymerizable components can result in a synergistic effect, resulting in a pretreatment composition having a more favorable combination of properties (e.g., low viscosity, good etch resistance, and film stability) as compared to a pretreatment composition having a single polymerizable component. In one example, the pretreatment composition is a mixture of 1, 12-dodecanediol diacrylate and tricyclodecane dimethanol diacrylate. In another example, the pretreatment composition is a mixture of tricyclodecane dimethanol diacrylate and tetraethylene glycol diacrylate. The pretreatment composition is typically selected such that one or more components of the pretreatment composition polymerize (e.g., covalently bond) with one or more components of the imprint resist during polymerization of the composite polymerizable coating. In some cases, the pretreatment composition includes a polymerizable component that is also in the imprint resist, or a polymerizable component that has a common functional group (e.g., acrylate group) with one or more polymerizable components in the imprint resist. Suitable examples of pretreatment compositions include multifunctional acrylates such as those described herein, including propoxylated (3) trimethylolpropane triacrylate, and dipentaerythritol pentaacrylate.

The pretreatment composition can be selected such that its etch resistance generally corresponds to the etch resistance of the imprint resist, thereby promoting etch uniformity. In some cases, the pretreatment composition is selected such that the interface energy at the interface between the pretreatment composition and air exceeds the interface energy of the imprint resist used with the pretreatment composition, thereby promoting rapid spreading of the liquid imprint resist over the liquid pretreatment composition to form a uniform composite coating on the substrate prior to contact of the composite coating with the template. The interfacial energy between the pretreatment composition and air typically exceeds the interfacial energy between the imprint resist and air or between at least one component of the imprint resist and air by 0.5mN/m to 25mN/m, 0.5mN/m to 15mN/m, 0.5mN/m to 7mN/m, 1mN/m to 25mN/m, 1mN/m to 15mN/m, or 1mN/m to 7mN/m, although these ranges may vary based on the chemical and physical properties of the pretreatment composition and the imprint resist and the resulting interaction between the two liquids. When the difference between the surface energies is too low, a limited spreading of the imprint resist results, and the droplets maintain a spherical cap-like shape and are kept apart by the pretreatment composition. When the difference between the surface energies is too high, excessive spreading of the imprint resists results, with most of the imprint resists moving toward adjacent droplets, emptying the droplet center, so that the composite coating has a convex region above the droplet center. Thus, when the difference between the surface energies is too low or too high, the resulting composite coating is non-uniform, with regions that are significantly depressed or raised. When the difference in surface energy is properly selected, the imprint resist spreads out rapidly to obtain a substantially uniform composite coating. The advantageous selection of pretreatment composition and imprint resist reduces the fill time by 50-90%, such that filling can be achieved in as little as 1 second, or in some cases even as little as 0.1 second.

Referring to operation 402 of the process 400, FIG. 5A depicts a substrate 102 including a base 500 and an adhesive layer 502. The substrate 500 is typically a silicon wafer. Other suitable materials for substrate 500 include fumed silica, quartz, silicon, germanium, gallium arsenide, and indium phosphide. The adhesive layer 502 serves to increase the adhesion of the polymer layer to the substrate 500, thereby reducing the formation of defects in the polymer layer during separation of the template from the polymer layer after polymerization of the composite coating. The thickness of the adhesion layer 502 is typically between 1nm and 10 nm. Examples of suitable materials for the adhesive layer 502 include U.S. patent nos. 7,759,407; 8,361,546, respectively; 8,557,351, respectively; 8,808,808, respectively; and 8,846,195, all of which are incorporated herein by reference. In one example, the adhesive layer is formed from a composition comprising ISORAD 501, CYMEL 303ULF, CYCAT 4040, or TAG 2678 (quaternary ammonium terminated trifluoromethanesulfonic acid), and PM Acetate (a solvent consisting of 2- (1-methoxy) propyl Acetate, available from Eastman chemical company of Kingsport, TN). In some cases, the substrate 102 includes one or more additional layers between the base 500 and the adhesive layer 502. In some cases, the substrate 102 includes one or more additional layers on the adhesive layer 502. For simplicity, the substrate 102 is depicted as including only the base 500 and the adhesive layer 502.

Fig. 5B depicts the pretreatment composition 504 after the pretreatment composition has been disposed on the substrate 102 to form a pretreatment coating 506. As shown in fig. 5B, the pretreatment coating 506 is formed directly on the bond coat 502 of the substrate 102. In some cases, the pretreatment coating 506 is formed on another surface of the substrate 102 (e.g., directly on the base 500). The pretreatment coating 506 is formed on the substrate 102 using techniques such as spin coating, dip coating, Chemical Vapor Deposition (CVD), Physical Vapor Deposition (PVD), and the like. In the case of, for example, spin coating or dip coating, etc., the pretreatment composition may be dissolved in one or more solvents (e.g., Propylene Glycol Methyl Ether Acetate (PGMEA), and Propylene Glycol Monomethyl Ether (PGME), etc.) for application to the substrate, and then the solvent is evaporated off to leave a pretreatment coating. Thickness t of pretreatment coating 506_pTypically atBetween 1nm and 100nm (e.g., between 1nm and 50nm, between 1nm and 25nm, or between 1nm and 10 nm).

Referring again to FIG. 4, operation 404 of process 400 includes disposing droplets of imprint resist on the pretreatment coating such that each droplet of imprint resist covers a target area of the substrate. The volume of the imprint resist droplets is typically between 0.6pL and 30pL, and the distance between the droplet centers is typically between 35 μm and 350 μm. In some cases, the volume ratio of the imprint resist to pretreatment composition is between 1:1 and 15: 1. In operation 406, a composite coating is formed on the substrate as each drop of imprint resist spreads beyond its target area. As used herein, "pre-spreading" refers to the spontaneous spreading of droplets of imprint resist that occurs between the time when the droplets initially contact the pretreatment coating and spread beyond the target area and the time when the template contacts the composite coating.

Fig. 6A-6D depict top-down views of the drops of imprint resist on the pretreatment coating as they are deposited on the target area, and of the composite coating before, during, and at the end of the drop deployment. Although the droplets are described as a square grid, the droplet pattern is not limited to a square or geometric pattern.

Fig. 6A depicts a top-down view of a droplet 600 on a pretreatment coating 506 at a time when the droplet was initially disposed on the pretreatment coating such that the droplet covered but did not extend beyond a target area 602. After the droplet 600 is disposed on the pretreatment coating 506, the droplet spontaneously spreads to cover a surface area of the substrate larger than the target area, whereby a composite coating is formed on the substrate. Fig. 6B depicts a top-down view of the composite coating 604 during pre-deployment (after some deployment of the droplets 600 beyond the target area 602) and typically after some intermixing of the imprint resist and pretreatment composition. As shown, the composite coating 604 is a mixture of a liquid pretreatment composition and a liquid imprint resist, where region 606 contains a majority of the imprint resist ("rich" imprint resist) and region 608 contains a majority of the pretreatment composition ("rich" pretreatment composition). As pre-development advances, the composite coating 604 may form a more uniform mixture of pretreatment composition and imprint resist.

Deployment may be advanced until one or more regions 606 contact one or more adjacent regions 606. Fig. 6C and 6D depict the composite coating 604 at the end of deployment. As shown in fig. 6C, each region 606 expands to contact each adjacent region 606 at boundary 610, while region 608 decreases into discrete (discontinuous) portions between regions 606. In other cases, as shown in fig. 6D, region 606 is spread out to form a continuous layer such that region 608 is not resolvable. In fig. 6D, the composite coating 604 can be a homogeneous mixture of the pretreatment composition and the imprint resist.

FIGS. 7A-7D are cross-sectional views taken along lines w-w, x-x, y-y, and z-z of FIGS. 6A-6D, respectively. Fig. 7A is a cross-sectional view along line w-w of fig. 6A depicting a drop 600 of imprint resist covering a surface region of the substrate 102 corresponding to a target region 602. Each target region (and each droplet of the initial configuration) has a center represented by line c-c, and line b-b represents a position equidistant between the centers of the two target regions 602. For simplicity, the droplets 600 are depicted as the adhesion layer 502 contacting the substrate 102, and it is depicted that the imprint resist and pretreatment composition are not intermixed. FIG. 7B is a cross-sectional view along line x-x of FIG. 6B, depicting the composite coating 604 with areas 608 exposed between the areas 606 after the areas 606 have been deployed beyond the target area 602. FIG. 7C is a cross-sectional view at the end of pre-development along line y-y of FIG. 6C, depicting the composite coating 604 as a homogeneous mixture of pretreatment composition and imprint resist. As shown, region 606 has spread out to cover a larger surface of the substrate than in fig. 7B, and region 608 has decreased accordingly. The region 606 originating from the droplet 600 is depicted as a convex portion, however, the composite coating 604 may be substantially planar or include a concave region. In some cases, pre-deployment may continue beyond that depicted in FIG. 7C, while the imprint resist forms a continuous layer (with no or full or partial intermixing) on the pretreatment composition. FIG. 7D is a cross-sectional view along line z-z of FIG. 6D depicting the composite coating 604 at the end of development as a homogeneous mixture of pretreatment composition and imprint resist, wherein the recessed regions of the composite coating near the center cc of the drop meet at boundary 610 such that the thickness of the polymerizable coating at the drop boundary exceeds the thickness of the composite coating at the drop center. As shown in fig. 7C and 7D, the thickness of the composite coating 604 at a location equidistant between the centers of the two target regions may be different from the thickness of the composite coating at the center of one of the two target regions when the composite coating is in contact with the nanoimprint lithography template.

Referring again to fig. 4,

operations

408 and 410 of process 400 include contacting the composite coating with a template, and polymerizing the composite coating to yield a nanoimprint lithography stack having a composite polymer layer on a nanoimprint lithography substrate, respectively.

In some cases, as shown in fig. 7C and 7D, the composite coating 604 is a uniform mixture or a substantially uniform mixture (e.g., at the air-composite coating interface) at the end of pre-development (i.e., just prior to the composite coating contacting the template). In this manner, the template contacts a homogeneous mixture, with a large portion of the mixture typically originating from the imprint resist. Thus, the release properties of the imprint resist may generally dominate the interaction of the composite coating with the template, as well as the separation of the polymer layer from the template, including defect formation (or absence) due to the separation force between the template and the polymer layer.

However, as depicted in fig. 8A and 8B, the composite coating 604 may include

regions

608 and 606 that are rich in the pretreatment composition and rich in the imprint resist, respectively, such that the template 110 contacts regions of the composite coating 604 having different physical and chemical properties. For simplicity, the imprint resist in region 606 is described as having replaced the pretreatment coating such that region 606 is in direct contact with the substrate and does not exhibit intermixing. Thus, the thickness of the pretreatment composition in region 608 is not uniform. In fig. 8A, the maximum height p of the region 606 exceeds the maximum height i of the pretreatment composition, such that the template 110 primarily contacts the region 606. In FIG. 8B, the maximum height i of the region 608 exceeds the maximum height p of the imprint resist such that the template 110 primarily contacts the region 608. Thus, the separation of the template 110 from the resulting composite polymer layer and the defect density associated therewith is non-uniform and is based on different interactions between the template and the imprint resist and between the template and the pretreatment composition. Thus, for certain pretreatment compositions (e.g., pretreatment compositions comprising a single monomer or a mixture of two or more monomers but no surfactant), for composite coatings, it may be advantageous to form a uniform mixture, or at least a substantially uniform mixture, at the gas-liquid interface when the template contacts the composite coating.

Figures 9A-9C and 10A-10C are cross-sectional views depicting the template 110 and the composite coating 604 on the substrate 102 with the base 500 and the adhesive layer 502 before and during contact of the composite coating with the template, and after separation of the template from the composite polymer layer to yield a nanoimprint lithography stack. In FIGS. 9A-9C, the composite coating 604 is depicted as a homogeneous mixture of pretreatment composition and imprint resist. In FIGS. 10A-10C, the composite coating 604 is depicted as a non-uniform mixture of pretreatment composition and imprint resist.

Fig. 9A depicts a cross-sectional view of the initial contact of the template 110 with the uniform composite coating 900 on the substrate 102. In fig. 9B, the template 110 has been advanced toward the substrate 102 such that the composite coating 900 fills the recesses of the template 110. After the composite coating 900 is polymerized to provide a uniform polymer layer on the substrate 102, the template 110 is separated from the polymer layer. Figure 9C depicts a cross-sectional view of a nanoimprint lithography stack 902 having a uniform composite polymer layer 904.

FIG. 10A depicts a cross-sectional view of the initial contact of the template 110 with the composite coating 604 on the substrate 102. The non-uniform composite coating 1000 includes

regions

606 and 608. As shown, little or no intermixing occurs between the imprint resist in region 606 and the pretreatment composition in region 608. In fig. 10B, the template 110 has been advanced toward the substrate 102 such that the composite coating 1000 fills the recesses of the template 110. After the composite coating 1000 is polymerized to produce a non-uniform polymer layer on the substrate 102, the template 110 is separated from the polymer layer. Figure 10C depicts a cross-sectional view of a nanoimprint lithography stack 1002 having an inhomogeneous composite polymer layer 1004 with

regions

1006 and 1008 corresponding to

regions

606 and 608 of the inhomogeneous composite coating 1000. Thus, the chemical composition of the composite polymer layer 1002 is non-uniform or non-uniform and includes a region 1006 having a composition derived from a mixture rich in imprint resist and a region 1008 having a composition derived from a mixture rich in pretreatment composition. The relative size (e.g., exposed surface area, template-covered surface area, or volume) of

regions

1006 and 1008 may vary based at least in part on the degree of pre-spreading prior to contact of the composite coating with the template or the degree of spreading due to contact with the template. In some cases, regions 1006 may be separated or bounded by regions 1008 such that the composite polymer layer includes a plurality of central regions separated by boundaries, and the chemical composition of the composite polymer layer 1004 at the boundaries is different from the chemical composition of the composite polymer layer inside the central regions.

The above-described contact of the composite coating 604 with the template 110 may be performed under an atmosphere containing a condensable gas (hereinafter, referred to as a "condensable gas atmosphere"). As used herein, the condensable gas refers to a gas condensed and liquefied by capillary pressure generated when the recesses of the fine pattern formed on the template 110 and the gap between the mold and the substrate are filled with the gas under the atmosphere and the pretreatment composition and the imprint resist. When the composite coating is contacted with the template, the condensable gas is present as a gas in this atmosphere prior to contacting the pretreatment composition and imprint resist with the template 110.

When the composite coating layer is brought into contact with the template in a condensable gas atmosphere, the gas filling the concave portions of the fine pattern is liquefied, so that when bubbles disappear, excellent filling performance is produced. The condensable gas may be dissolved in the pretreatment composition and/or the imprint resist.

The boiling point of the condensable gas is not limited as long as the temperature is equal to or lower than the ambient temperature at the time of contact of the composite coating with the template. The boiling point is preferably from-10 ℃ to 23 ℃, more preferably from 10 ℃ to 23 ℃. Within this range, better filling performance results.

The vapour pressure of the condensable gas at ambient temperature when the composite coating is in contact with the template is not limited as long as the pressure is equal to or lower than the mould pressure at which the composite coating is imprinted when in contact with the template. The vapor pressure is preferably from 0.1 to 0.4 MPa. Within this range, better filling performance results. Vapor pressures greater than 0.4MPa at ambient temperature tend to be insufficiently effective for the disappearance of bubbles. On the other hand, a vapor pressure of less than 0.1MPa at ambient temperature tends to require reduced pressure and complicated equipment.

The ambient temperature at the time of contact of the composite coating with the template is not limited, and is preferably 20 ℃ to 25 ℃.

Specific examples of suitable condensable gases include fluorine-containing hydrocarbons including chlorofluorocarbons (CFCs) such as trichlorofluoromethane, Fluorocarbons (FCs), Hydrochlorofluorocarbons (HCFCs), Hydrofluorocarbons (HFCs) such as 1,1,1,3, 3-pentafluoropropane (CHF)₂CH₂CF₃HFC-245fa, PFP), and Hydrofluoroethers (HFE) such as pentafluoroethyl methyl ether (CF)₃CF₂OCH₃HFE-245 mc). Among them, from the viewpoint of excellent filling property at the time of contact of the composite coating layer with the template at an ambient temperature of 20 ℃ to 25 ℃,1,1,3, 3-pentafluoropropane (vapor pressure at 23 ℃: 0.14MPa, boiling point: 15 ℃), trichlorofluoromethane (vapor pressure at 23 ℃: 0.1056MPa, boiling point: 24 ℃) and pentafluoroethyl methyl ether are preferable. Further, from the viewpoint of excellent safety, 1,1,1,3, 3-pentafluoropropane is particularly preferable. One of these condensable gases may be used alone, or two or more of these condensable gases may be used as a mixture.

These condensable gases may be used as a mixture with non-condensable gases such as air, nitrogen, carbon dioxide, helium and argon. From the viewpoint of filling performance, helium is preferable as the non-condensable gas to be mixed with the condensable gas. Helium gas may permeate into the mold 205. Therefore, when the concave portions of the fine pattern formed on the mold 205 are filled with the gas (condensable gas and helium gas) and the pretreatment composition and/or the imprint resist in the atmosphere when the composite coating layer is in contact with the template, the condensable gas is liquefied while the helium gas is infiltrated into the mold.

The polymer layer obtained by separating the template from the composite polymer layer has a specific pattern shape. As shown in fig. 2, the remaining layer 204 may remain in an area other than the area having the formed pattern shape. In such a case, the remaining layer 204 existing in the region to be removed from the cured layer 202 having the obtained pattern shape is removed by the etching gas. As a result, a patterned cured layer having a desired pattern shape (e.g., a pattern shape resulting from the shape of the template 110) may be obtained without a remaining layer (i.e., desired portions on the surface of the substrate 102 are exposed).

In this context, examples of suitable methods for removing the residual layer 204 include a method involving removing the residual layer 204 present in the recessed portions of the cured layer 202 having the pattern shape by a technique such as etching, thereby exposing the surface of the substrate 102 of the recessed portions in the pattern of the cured layer 202 having the pattern shape.

In the case where the remaining layer 204 existing in the concave portion of the cured layer 202 having the pattern shape is removed by etching, a specific method thereof is not limited, and a conventional method known in the art, for example, dry etching using an etching gas, may be used. Conventional dry etching equipment known in the art may be used for dry etching. The etching gas is appropriately selected according to the elemental composition of the solidified layer to be subjected to this etching. For example, a halogen gas (e.g., CF) may be used₄、C₂F₆、C₃F₈、CCl₂F₂、CCl₄、CBrF₃、BCl₃、PCl₃、SF₆And Cl₂) Oxygen atom-containing gas (e.g., O)₂CO and CO₂) Inactive gas (e.g. He, N)₂And Ar), or a compound such as H₂Or NH₃And the like. These gases may be used as a mixture.

When the base material 102 (base material to be treated) used is a base material whose adhesion to the cured layer 202 is improved by surface treatment such as silane coupling treatment, silazane treatment, and organic film formation, such a surface-treated layer may also be removed by etching, followed by etching of the remaining layer existing in the concave portion of the cured layer 202 having a pattern shape.

The above-described production method can produce a patterned cured layer having a desired pattern shape (pattern shape derived from the shape of the template 110) at a desired position without remaining layers, and can produce an article having the patterned cured layer. The substrate 102 may be further processed as described herein.

The obtained patterned cured layer may be used, for example, in semiconductor processing described later, or may also be used as an optical member (including use as part of an optical member) such as a diffraction grating or a polarizer, thereby obtaining an optical component. In such a case, an optical assembly having at least the substrate 102 and the patterned cured layer disposed on the substrate 102 can be prepared. For the reverse tone process, a separate etching of the remaining layer is not required. However, it should be understood that the adhesion layer etch is compatible with the resist etch.

After the removal of the remaining layers, the patterned cured layer 304 having no remaining layers is used as a resist film in dry etching of the portion of the substrate 102 whose surface is exposed. Conventional dry etching equipment known in the art may be used for dry etching. The etching gas is appropriately selected depending on the elemental composition of the cured layer to be subjected to this etching and the elemental composition of the base material 102. For example, a halogen gas (e.g., CF) may be used₄、C₂F₆、C₃F₈、CCl₂F₂、CCl₄、CBrF₃、BCl₃、PCl₃、SF₆And Cl₂) Oxygen atom-containing gas (e.g., O)₂CO and CO₂) Inactive gas (e.g. He, N)₂And Ar), or a compound such as H₂Or NH₃And the like. These gases may be used as a mixture. The etching gas used for removing the above-mentioned remaining layer and the etching gas used for the substrate treatment may be the same or different.

As previously described, a non-uniform mixture of the pretreatment composition and the imprint resist may be formed in the cured layer 202 having a pattern shape.

The pretreatment composition preferably has a dry etch resistance that is nearly the same as the imprint resist. This allows the substrate 102 to be advantageously treated even in areas having a high concentration of the pretreatment composition. As a result, the substrate 102 can be uniformly processed.

In addition to the above-described series of steps (production process), electronic components may be formed so as to obtain a circuit structure of a pattern shape based on a shape derived from the template 110 on the substrate 102. Thus, a circuit substrate for use in a semiconductor device or the like can be produced. Examples of such semiconductor devices include LSIs, system LSIs, DRAMs, SDRAMs, RDRAMs, D-RDRAMs, and NAND flash memories. The circuit substrate can also be connected to, for example, a circuit control mechanism for the circuit substrate to form electronic equipment such as displays, cameras, and medical devices.

Likewise, the patterned cured product having no remaining layer can also be used as a resist film in substrate processing by dry etching to produce an optical component.

Alternatively, a quartz substrate may be used as the substrate 102, and the patterned cured product 202 may be used as a resist film. In such a case, the quartz substrate may be processed by dry etching to prepare a replica (replica mold) of the quartz imprint mold.

In the case of preparing a circuit substrate or an electronic component, the patterned cured product 202 may be finally removed from the processed substrate or may be configured to remain as a member constituting a device.

Examples

In the examples described below, the reported interface at the interface between the imprint resist and air can be measured by maximum bubble pressure. The measurement was carried out using a BP2 bubble pressure tensiometer manufactured by Kruss GmbH of Hamburg, Germany. In the maximum bubble pressure method, the maximum internal pressure of a bubble formed in a liquid by means of a capillary is measured. Using a capillary of known diameter, the surface tension can be calculated from the young-laplace equation. For the pretreatment composition, the interface at the interface between the pretreatment composition and the air can be measured by the maximum bubble pressure method, or obtained as a value reported by the manufacturer.

Viscosity was measured using a temperature controlled bath set at 23 ℃ using a Brookfield DV-II + Pro with a small sample adapter. The reported viscosity values are the average of five measurements.

Preparing a bonding layer formed on a substrate as follows: an adhesive composition made by combining about 77g of ISORAD 501, about 22g cymel 303ULF, and about 1g of TAG 2678, and introducing the mixture to about 1900g of PM Acetate was cured. The adhesive composition is spin coated onto a substrate (e.g., a silicon wafer) at a spin speed between 500 and 4,000 revolutions per minute to provide a substantially smooth planar layer having a uniform thickness. The spin-coated composition was exposed to thermal actinic energy (thermal energy) at 160 ℃ for approximately 2 minutes. The resulting adhesion layer is about 3nm to about 4nm thick.

In comparative example 1 and examples 1-3, an imprint resist having a surface tension of 33mN/m at the air/imprint resist interface was used to demonstrate the spreading of the imprint resist on various surfaces. An imprint resist is a polymerizable composition comprising: about 45 wt% of monofunctional acrylates (e.g., isobornyl acrylate and benzyl acrylate), about 48 wt% of difunctional acrylates (e.g., neopentyl glycol diacrylate), about 5 wt% of photoinitiators (e.g., TPO and 4265), and about 3 wt% of surfactants (e.g., X-R- (OCH)₂CH₂)_nOH, wherein R is alkyl, aryl, or poly (propylene glycol), X is H or- (OCH)₂CH₂)_nOH, n is an integer (e.g., 2 to 20, 5 to 15, or 10 to 12) (e.g., X ═ OCH₂CH₂)_nOH, R ═ poly (propylene glycol), n ═ 10-12) and fluorosurfactants, where X ═ a mixture of perfluorinated alkyl groups).

In comparative example 1, the imprint resist was disposed directly on the adhesive layer of the nanoimprint lithography substrate. Fig. 11 is an image of droplets 1100 of imprint resist on a bonding layer 1102 of a substrate 1.7 seconds after the start of dispensing of droplets in a grid pattern. As can be seen in this image, the droplet 1100 has spread out from the target area on the substrate. However, spreading beyond the target area is limited and the exposed adhesive layer 1102 has an area exceeding that of the target areaArea of drop 1100. rings visible in this and other images, such as ring 1104, are newton interference rings that represent differences in thickness in various regions of the drop. resist drop size of about 2.5 pL. fig. 11 has a 2 × 7 (pitch)²A staggered grid of droplets (e.g., 2 units in the horizontal direction with 3.5 units between lines). Each wire is then shifted 1 unit horizontally.

Examples 1-3 in which pretreatment compositions A-C were disposed on nanoimprint lithography substrates, respectively, to form a pretreatment coating, droplets of imprint resist were disposed on the pretreatment coating FIGS. 12-14 show images of the composite coating after dispensing of the droplets of imprint resist began, although intermixing occurred between the pretreatment composition and the imprint resist in these examples, droplets of imprint resist and pretreatment coating are described below without reference to intermixing for simplicity and convenience the pretreatment composition was disposed on a wafer substrate via spin coating more particularly, the pretreatment composition was dissolved in PGMEA (0.3 wt% pretreatment composition/99.7 wt% PGMEA) and spin coated on the wafer substrate upon evaporation of the solvent, typical thickness of the resulting pretreatment coating on the substrate is in the range of 5nm to 10nm (e.g., 8 nm). in FIGS. 12-14, the resist droplet size was approximately 2.5 pL. FIGS. 12 and 14 have a 2 × 7 (pitch)²Of droplets (e.g., 2 units in the horizontal direction with 3.5 units between lines), each line below is moved 1 unit in the horizontal direction, figure 13 shows 2 × 6 (pitch)²A staggered grid of droplets. The pitch value was 84.5. mu.m. The volume ratio of the resist to the pretreatment layer is in the range of 1 to 15 (e.g., 6-7).

Table 1 lists the surface tensions (air/liquid interfaces) of the pretreatment compositions A-C and imprint resists used in examples 1-3.

TABLE 1 surface tension of pretreatment compositions

In example 1 (see table 1), droplets of imprint resist were disposed on a substrate having a coating of pretreatment composition a (Sartomer492 or "SR 492"). SR492, available from Sartomer, Inc. (USA, Pa.), is propoxylated (3) trimethylolpropane triacrylate (a multifunctional acrylate). Fig. 12 shows an image of a drop 1200 of imprint resist and the resulting composite coating 1204 on the pretreatment coating 1202 1.7 seconds after the start of dispensing of the discrete portions in a staggered grid pattern. In this embodiment, the drop retains its spherical cap-like shape and the spreading of the imprint resist is limited. As can be seen in fig. 12, in comparative example 1 when the spread of the drops 1200 exceeds the spread of the imprint resist on the adhesive layer, the drops are kept apart by the pretreatment coating 1202, which forms a boundary 1206 around the drops. The particular components of the imprint resist spread out beyond the center of the droplet, forming a region 1208 around the droplet 1200. The regions 1208 are separated by the pretreatment coating 1202. The limited spreading is at least partly due to the small difference in surface tension (1mN/m) between the pretreatment composition a and the imprint resist, so that there is no significant energy advantage for the spreading of the droplets. It is also understood that other factors such as friction affect the degree of deployment.

In example 2 (see table 1), droplets of imprint resist were disposed on a substrate having a coating of pretreatment composition B (Sartomer351HP or "SR 351 HP"). SR351HP, available from Sartomer, inc. (usa, pa), is trimethylolpropane triacrylate (a multifunctional acrylate). Fig. 13 shows an image of droplets 1300 of imprint resist and the resulting composite coating 1304 on the pretreatment coating 1302 1.7 seconds after the start of dispensing of the droplets in a square lattice pattern. After 1.7 seconds, the droplets 1300 cover most of the surface area of the substrate and are separated by the pretreatment coating 1302, which forms a boundary 1306 around the droplets. The droplet 1300 was more uniform than the droplet 1200 in example 1, and thus a significant improvement in spreading was observed over example 1. The greater degree of spreading is at least partially attributed to the greater difference in surface tension between the pretreatment composition B and the imprint resist than between the pretreatment composition a of example 1 and the imprint resist (3.1 mN/m).

In example 3 (see table 1), droplets of imprint resist were disposed on a substrate having a coating of pretreatment composition C (Sartomer399LV or "SR 399 LV"). SR399LV, available from Sartomer, inc. (usa, pa), is dipentaerythritol pentaacrylate (a multifunctional acrylate). Fig. 14 shows an image of droplets 1400 of imprint resist and the resulting composite coating 1404 on a pre-treatment coating 1402 1.7 seconds after the start of dispensing of the droplets in a triangular lattice pattern. As can be seen in fig. 14, droplets 1400 are separated at boundary 1406 by pretreatment coating 1402. However, most of the imprint resist accumulates at the droplet boundaries, so that most of the polymerizable material is at the droplet boundaries and the droplet center is essentially empty. The degree of spreading is at least partly due to the large difference in surface tension between the pretreatment composition C and the imprint resist (6.9 mN/m).

The defect density was measured as a function of the pre-open time for the imprint resists of examples 1-3 and pretreatment composition B of example 2. Fig. 15 shows the defect density (voids) due to the unfilled template. Curve 1500 shows the defect density (per cm) as a function of the unwind time (seconds) for a 28nm line/space pattern area²The number of defects) of the substrate, wherein the defect density is close to 0.1/cm at 0.9 seconds². Curve 1502 shows defect density (per cm) as a function of deployment time (seconds) over the entire field with a range of feature sizes²Number of defects) in which the defect density approaches 0.1/cm at 1 second². By comparison, a deployment time of between 2.5 seconds and 3.0 seconds for the entire field typically achieves close to 0.1/cm without pretreatment²The defect density of (2).

The properties of the pretreatment compositions PC1-PC9 are shown in Table 2. The key to PC1-PC9 is shown below. The viscosity was measured at a temperature of 23 ℃ as described in the text. To calculate the diameter ratio at 500ms as shown in table 2, the droplets of the imprint resist (droplet size 25pL) were spread on a substrate coated with the pretreatment composition (thickness of about 8 to 10 nm) on the adhesive layer, and the droplet diameter was recorded at the 500ms elapsed time. The droplet diameter at 500ms with each pretreatment composition was divided by the droplet diameter of the imprint resist on the bonding layer without the pretreatment composition. As shown in table 2, the drop diameter of the imprint resist on PC1 at 500ms was 60% larger than the drop diameter of the imprint resist on the adhesive layer without the pretreatment coating. Fig. 16 shows the droplet diameter (μm) as a function of time (ms) for pretreatment compositions PC1-PC 9. The relative etch resistance is the Ohnishi parameter of each pretreatment composition divided by the Ohnishi parameter of the imprint resist. The relative etch resistance (ratio of etch resistance of pretreatment composition to etch resistance of imprint resist) of PC1-PC9 is shown in table 2.

TABLE 2 Performance of pretreatment compositions PC1-PC9

PC 1: trimethylolpropane triacrylate (Sartomer)

PC 2: trimethylolpropane ethoxylate triacrylate, n.about.1.3 (Osaka Organic)

PC 3: 1, 12-dodecanediol diacrylate

PC 4: poly (ethylene glycol) diacrylate, Mn, average 575(Sigma-Aldrich)

PC 5: tetraethyleneglycol diacrylate (Sartomer)

PC 6: 1, 3-adamantanediol diacrylate

PC 7: nonoyl glycol diacrylate

PC 8: m-xylylene diacrylate

PC 9: dicyclodecane dimethanol diacrylate (Sartomer)

The pretreatment compositions PC3 and PC9 were combined in various weight ratios to give pretreatment compositions PC10-PC13 having the weight ratios shown in table 3. Comparison of the properties of PC3 and PC9 with the mixtures formed therefrom revealed synergistic effects. For example, PC3 has a relatively low viscosity and allows for relatively fast template filling, but has relatively poor etch resistance. In contrast, PC9 had relatively good etch resistance and film stability (low evaporation loss), but was relatively viscous and indicated relatively slow template filling. However, the combination of PC3 and PC9 resulted in a pretreatment composition having a combination of advantageous properties, including relatively low viscosity, relatively fast template filling, and relatively good etch resistance. For example, a pretreatment composition having 30 wt% PC3 and 70 wt% PC9 was found to have a surface tension of 37.2mN/m, a diameter ratio of 1.61, and an Ohnishi parameter of 3.5.

TABLE 3 composition of pretreatment composition PC10-PC13

Pretreatment composition	PC3(wt％)	PC9(wt％)
			PC10	25	75
PC11	35	65
			PC12	50	50
PC13	75	25

Fig. 17A shows plots of the viscosity of pretreatment compositions including various ratios of PC3 and PC9 (i.e., 100 wt% PC3 to 100 wt% PC 9). Fig. 17B shows droplet diameters (measured as described with respect to table 2) for PC3, PC13, PC12, PC11, PC10, and PC 9. FIG. 17C shows the fraction of surface tension (mN/m) with respect to PC3 and PC 9.

A number of embodiments have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. Accordingly, other embodiments are within the scope of the following claims.

Claims

1. An imprinting method, characterized in that it comprises:

disposing discrete portions of an imprint resist on a liquid pretreatment coating on a substrate such that the discrete portions of the imprint resist are spread out on the liquid pretreatment coating, thereby resulting in a spread-out imprint resist, wherein the liquid pretreatment coating comprises a polymerizable component and the imprint resist is a polymerizable composition;

contacting the unrolled imprint resist with a template; and

polymerizing the developed imprint resist and the pretreatment coating resulting in a polymer layer on the substrate;

wherein the surface tension of the liquid pretreatment coating exceeds the surface tension of the imprint resist.

2. The embossing method of claim 1, wherein the liquid pretreatment coating does not contain a polymerization initiator.

3. An imprinting method according to claim 1, wherein the developed imprint resist and the liquid pretreatment coating form a composite polymerizable coating prior to contacting the developed imprint resist with the template.

4. The imprinting method of claim 1, further comprising separating the template from the polymer layer.

5. The embossing method of claim 1, wherein the liquid pretreatment coating on the substrate has a thickness between 1nm and 15 nm.

6. The imprint method according to claim 1, wherein a surface tension of the liquid pretreatment coating exceeds a surface tension of the imprint resist by 0.5mN/m to 25 mN/m.

7. A method of manufacturing a semiconductor device, the method comprising:

disposing a liquid pretreatment coating on a substrate, wherein the liquid pretreatment coating comprises a polymerizable component;

disposing discrete portions of an imprint resist on the liquid pretreatment coating such that the discrete portions of the imprint resist spread out on the liquid pretreatment coating, thereby resulting in a spread-out imprint resist, wherein the imprint resist is a polymeric composition and the surface tension of the pretreatment coating exceeds the surface tension of the imprint resist;

contacting the unrolled imprint resist with a template;

polymerizing the developed imprint resist and the pretreatment coating to obtain a polymer layer on the substrate,

separating the template from the polymer layer; and

etching the substrate through the polymer layer.

8. The method of claim 7, wherein:

disposing the liquid pretreatment coating comprises coating the substrate using spin coating, dip coating, chemical vapor deposition CVD, or physical vapor deposition PVD, and

further comprising:

processing the substrate using an imprint lithography system to obtain a polymer layer on the substrate; and

the substrate is etched using reactive ion etching or high density etching.