CN112859520A

CN112859520A - Low-energy-curing photoresist, resist pattern and preparation method thereof

Info

Publication number: CN112859520A
Application number: CN202110078019.8A
Authority: CN
Inventors: 王继宝; 周翠苹
Original assignee: Shenzhen Sapience Technology Co ltd
Current assignee: Shenzhen Sapience Technology Co ltd
Priority date: 2021-01-20
Filing date: 2021-01-20
Publication date: 2021-05-28

Abstract

The application relates to the field of photoresist, and particularly discloses a low-energy-cured photoresist, a resist pattern and a preparation method thereof. The photoresist comprises the following components in parts by weight: a: 30-80 parts of carboxyl-containing acrylate polymer, B: photodegradation of conjugated oligomer, C: 3-15 parts of a photopolymerization initiator, D: 1-30 parts of melamine derivative, E: 1-10 parts of diamine compound, wherein the sum of the parts by weight of the component A and the component B is 100 parts; the application also discloses a resist pattern which is prepared from the photoresist; the preparation method of the resist pattern comprises the following steps: a, B, C, D, E is weighed and mixed evenly to prepare ethanol solution which is sprayed to form a photosensitive film; pressing the photosensitive film onto the FPC substrate; projecting a circuit pattern to solidify the photoresist; and cleaning to obtain the resist pattern. The photoresist has the advantages of low energy, fast curing and high resolution; the thickness of the resist pattern is small, and the resolution is high; the method is simple to operate and high in preparation efficiency.

Description

Low-energy-curing photoresist, resist pattern and preparation method thereof

Technical Field

The present application relates to the field of photoresists, and more particularly, to a low energy cured photoresist, resist pattern and methods of making the same.

Background

Photoresist, also called photoresist, is a key chemical material in the micro-processing technology, and the properties of the photoresist, such as solubility, adhesiveness and the like, can be obviously changed before and after exposure; photoresists are used primarily for the transfer of circuit patterns to substrates for the preparation of microelectronic circuits, as well as the microfabrication of integrated circuits and semiconductor discrete devices.

The Chinese patent with the publication number of CN101162365B discloses a photosensitive resin composition, a preparation method and a film forming method thereof, wherein the composition comprises 18-65% of light-cured resin, 30-80% of organic solvent and 0.02-6% of photoinitiator, and the composition can be applied to photoresist; when the photosensitive resin composition is irradiated by light, light spots are generated on a photosensitive film formed by the photosensitive resin composition, and the photoinitiator absorbs the energy of the light spots to promote the curing of the photocuring resin and further cure the photoresist.

With respect to the related art among the above, the inventors consider that the following technical problems exist: the energy at the edge of the light spot is lower than that at the center of the light spot, and when the light-cured resin in the related art receives the energy irradiation at the edge of the light spot, the curing rate of the light-cured resin is slower, which results in a smaller gel fraction of the photoresist, and the resolution of the photoresist is reduced.

Disclosure of Invention

In order to rapidly cure the photoresist at the edge of the light spot, the application provides a low-energy cured photoresist, a resist pattern and a preparation method thereof.

The low-energy-curing photoresist, the resist pattern and the preparation method thereof adopt the following technical scheme:

in a first aspect, the present application provides a low energy cured photoresist, which adopts the following technical scheme:

the low-energy-cured photoresist is characterized by comprising the following components in parts by weight:

a: 30-80 parts of carboxyl-containing acrylate polymer, B: photodegradation of conjugated oligomer, C: 3-15 parts of a photopolymerization initiator, D: 1-30 parts of melamine derivative, E: 1-10 parts of a diamine compound; wherein the sum of the parts by weight of A and B is 100 parts.

When the photoresist is formed, C initiates A to generate polymerization reaction under the irradiation of light, so as to promote the curing of the photoresist; however, at the edge of the light spot with lower energy, the polymerization reaction rate of the A is slower, so that the photoresist is slower in curing and is not easy to form; the D can perform nucleophilic addition reaction with the A, so that the crosslinking degree of the reaction is increased, and the edge of a photoresist spot is rapidly cured and molded, thereby improving the gel rate of the photoresist; however, after the D and the A are crosslinked, the thickness of the photosensitive film is increased, so that the resolution of the photoresist is reduced; the B molecules are highly conjugated and have a wide light absorption range, and the B has good photodegradability, so that the polymers in the components can be promoted to be degraded into small molecular substances under illumination, the small molecular substances are volatilized from the components, the thickness of a photosensitive film is reduced, and the resolution of the photoresist is improved; but B is easy to react with oxygen and easily loses photodegradability in air; e has stronger reducibility, can preferentially react with oxygen, plays a role in protecting B and lightens the influence of air on the curing of the photoresist; the B, D, E of the present application cooperate to promote rapid curing of the photoresist at the edges of the spot while having high resolution.

Preferably, the photoresist comprises the following components in parts by weight:

a: 55-65 parts of carboxyl-containing acrylate polymer, B: photodegradation of conjugated oligomer, C: 8-12 parts of a photopolymerization initiator, D: 12-16 parts of melamine derivative, E: 4-6 parts of a diamine compound; wherein the sum of the parts by weight of A and B is 100 parts.

By adopting the technical scheme, the photoresist composed of the components is cured more quickly and has higher resolution under the irradiation of low-energy irradiation light.

Preferably, the B is a polysilane oligomer, and the molecular weight of the B is 1100-1800.

By adopting the technical scheme, a large conjugated system exists in the molecules of the polysilane oligomer, and the polysilane oligomer has a wide spectrum absorption band; when light irradiates on the photoresist, the polysilane oligomer with the molecular weight absorbs the energy of the irradiated light, so that the polymer formed by crosslinking the A and the D is degraded into small molecular substances and volatilized from the photosensitive film, the thickness of the photosensitive film is reduced, and the resolution of the photoresist is improved; meanwhile, the thickness of the photosensitive film is reduced, so that the curing molding of the photoresist at the edge of the light spot is facilitated, the low-energy curing rate of the photoresist is increased, and the gel rate of the photoresist is increased.

In the process of forming a multilayer resist pattern, O is mostly used₂-RiE etching the etched face; the polysilane oligomer is rich in silicon element in O₂RiE, Si forms SiO on the polymer surface in the composition₂The thin layer plays a role in protecting the polymer; using polysilane oligomer pairs₂RiE, which enables the photoresist to form multiple layers of photosensitive films on the platelet coating, resulting in high resolution images.

Preferably, the molecular weight of A is 88 w-109 w.

By adopting the technical scheme, when the molecular weight of A is in the range, the photoresist is uniformly cured, small molecular polymerization byproducts are not easy to dope, and high-purity high polymers are easier to form, so that the resolution of the photoresist is increased.

Preferably, the C is oxime ester photoinitiator or ferrocene photoinitiator.

By adopting the technical scheme, the oxime ester photoinitiator and the ferrocene photoinitiator can efficiently absorb irradiation light and promote the photopolymerization reaction of the other components in the photoresist, so that the photoresist is finally cured; compared with oxime ester photoinitiators, the ferrocene photoinitiator has higher sensitivity for absorbing light and higher initiation activity, so that photopolymerization can be initiated more quickly, and the gel fraction of the photoresist is increased.

Preferably, the ferrocene photoinitiator is carbonyl modified ferrocene.

By adopting the technical scheme, the carbonyl can be conjugated with cyclopentadiene in ferrocene, so that the light absorption activity of cyclopentadiene is increased, carbonyl modified ferrocene has a larger photoinitiation rate, and the curing rate of the photoresist is increased.

In a second aspect, the present application provides a resist pattern, which adopts the following technical solution:

a resist pattern is mainly prepared from the photoresist.

By adopting the technical scheme, the resist pattern formed by the photoresist has small thickness, high resolution and good flexibility, and is suitable for manufacturing FPC.

In a third aspect, the present application provides a method for preparing a resist pattern, which adopts the following technical scheme:

a method of preparing a resist pattern, the method comprising the steps of:

a, B, C, D, E are weighed according to the weight portion and are evenly mixed to obtain a mixture;

dissolving the mixture in ethanol to obtain an alcohol solution with the mass fraction of 30-60%;

spraying the alcohol solution on a transparent support to form a photosensitive film;

in a vacuum environment, controlling the temperature to be 50-70 ℃ and the pressure to be 0.3-0.5 Mpa, and connecting the photosensitive film to the FPC substrate in a pressing way;

projecting the circuit pattern onto the photosensitive film, and solidifying the projected part;

the non-projected portion of the photosensitive film is washed away with an alkaline solution, and the resist pattern is formed on the cured portion.

By adopting the technical scheme, the method is simple to operate, the pattern can be imprinted on the photosensitive film only by dry projection, the preparation efficiency is high, and the large-scale production is facilitated.

In summary, the present application has the following beneficial effects:

1. d, B and E are added into an A, C photocuring system, and D can perform nucleophilic addition with A to promote the curing reaction of A, so that the low-energy curing rate of the photoresist is improved; after D and A are polymerized, the resolution of the photoresist is lower; b, under the irradiation of light, the macromolecular polymer is promoted to be degraded into small molecular substances and volatilize, so that the thickness of the photosensitive film is reduced, and the resolution of the photoresist is increased; but B is susceptible to oxidative loss in air; e has stronger reducibility and plays a role in protecting B; therefore, the photoresist of the application has the advantages of quick low-energy curing and high resolution.

2. The polysilane oligomer is selected as the B, and the B promotes the volatilization of the macromolecular polymer in the photosensitive film into the micromolecular substance under the action of irradiating light, so that the thickness of the cured photoresist is reduced, and the thickness of the cured photoresist is increasedThe resolution of the photoresist is added; meanwhile, the B molecule is rich in silicon element and can be in O₂Formation of SiO during etching of-RiE₂And the thin layer plays a role in protecting the photoresist, so that the photoresist can be superposed with a plurality of layers on the substrate, and the high-resolution image is generated.

3. The photoinitiator is preferably carbonyl modified ferrocene, and compared with ferrocene, the carbonyl modified ferrocene molecule has a larger conjugated system, a wider absorption spectrum range and a larger photodegradation rate, and the curing rate of the photoresist is increased.

4. The resist pattern of the present application has a small thickness and excellent resolution.

5. The preparation method of the resist pattern is simple to operate, the pattern can be printed and engraved on the photosensitive film only by dry projection, the preparation efficiency is high, and the large-scale production is facilitated.

Detailed Description

The present application will be described in further detail with reference to examples.

The raw materials of the embodiment can be obtained by market, wherein, the ferrocenecarboxylic acid N-succinimidyl ester is purchased from Shanghai Xiansding Biotech limited company; bisphenol A dimethacrylate was purchased from chemical Co., Ltd, Kiyowan, Hubei; hexamethylenemelamine was purchased from Shanghai Merlin Biotech, Inc.; dinitrile diamines were purchased from Shandong Kaya chemical Co., Ltd; ferrocene is purchased from zhuohai industries ltd, hannam, henna; the polysilane oligomer was purchased from osaka gas chemistry (shanghai) ltd and had an average molecular weight of 1500.

Preparation examples of raw materials

Preparation example 1: preparation of A with a molecular weight of 88w

S1, weighing methyl propionate, methyl methacrylate and butyl acrylate, and putting into a reaction kettle according to the mass ratio of 22:71: 7;

s2, introducing N into the reaction kettle₂With butyl acrylate: the weight ratio of manganese dioxide is 10: 1 adding manganese dioxide into the reaction kettle, controlling the temperature to be 56 ℃, and reacting for 5 hours at 50r/min to obtain A.

Preparation example 2: preparation of A with a molecular weight of 100w

s2, introducing N into the reaction kettle₂With butyl acrylate: the weight ratio of manganese dioxide is 7: 1 adding manganese dioxide into a reaction kettle, controlling the temperature to be 62 ℃, and reacting for 6 hours at 50r/min to obtain A.

Preparation example 3: preparation of A with a molecular weight of 109w

s2, introducing N into the reaction kettle₂With butyl acrylate: the weight ratio of manganese dioxide is 5: 1 adding manganese dioxide into the reaction kettle, controlling the temperature to be 65 ℃, and reacting for 7 hours at the speed of 50r/min to obtain A.

Preparation example 4: preparation of A with a molecular weight of 120w

s2, introducing N into the reaction kettle₂With butyl acrylate: the weight ratio of manganese dioxide is 3: 1 adding manganese dioxide into the reaction kettle, controlling the temperature to be 68 ℃, and reacting for 8.5h at 50r/min to obtain A.

Preparation example 5: preparation of A with a molecular weight of 50w

s2, introducing N into the reaction kettle₂Controlling the temperature to be 60 ℃, and reacting for 6h at 50r/min to obtain A.

Examples

Examples 1 to 7

As shown in Table 1, the main difference between examples 1 to 7 is that the raw material ratios are different. Wherein, A is prepared from preparation example 2; b, selecting a polysilane oligomer; selecting an oxime ester photoinitiator, and preparing the oxime ester photoinitiator by the preparation method of the embodiment 3 in the application publication No. CN 110066352A; d, selecting hexamethylol melamine; e is dinitrile diamine.

TABLE 1

Examples 8 to 13

Examples 8 to 13 are different from example 4 in that a ferrocene photoinitiator is used as C.

As shown in Table 2, examples 8 to 13 are different in the type and content of C. Wherein, the carbonyl modified ferrocene is ferrocenecarboxylic acid N-succinimidyl ester.

TABLE 2

Example 14

This example differs from example 4 in that a was prepared from preparation 1.

Example 15

This example differs from example 4 in that a was prepared from preparation 3.

Comparative examples

Comparative example 1

This comparative example is compared to example 4, except that a was prepared from preparation 4.

Comparative example 2

This comparative example is compared to example 4, except that a was prepared from preparation 5.

Comparative example

Comparative example 1

A photosensitive resin composition disclosed in example 4 of the grant publication No. CN 101162365B.

Comparative example 2

This comparative example compares to example 4, with the absence of D in the composition and the mass of A adjusted up to 760 g.

Comparative example 3

This comparative example is compared to example 4, with the absence of B in the composition.

Comparative example 4

This comparative example has a composition lacking E as compared to example 4.

Detection method

Preparing an anti-reagent pattern:

s1, mixing the components of the examples 1-13, the comparative examples 1-2 and the comparative examples 1-4 respectively to obtain a mixture;

s2, dissolving the mixture in 75% ethanol by volume fraction to prepare 50% alcohol solution by mass fraction;

s3, spraying the alcohol solution on a PET film with the thickness of 25 mu m to form a coating layer; placing the coating layer in a hot air circulation type drying oven, drying at 100 deg.C for 5min, and removing ethanol to form photosensitive film;

s4, pressing the polyethylene film as a protective film on the photosensitive film;

s5, brushing and drying the surface of the FPC substrate with the copper foil surface and the thickness of 35 microns by using a steel wire brush;

s6, peeling the polyethylene film from the photosensitive film, utilizing an MD450-100T type vacuum laminating machine, controlling the temperature at 60 ℃, controlling the pressure at 0.4MPa, carrying out vacuum pressurization for 20S, pressing the photosensitive film onto the copper foil surface of the FPC substrate, cooling to 23 ℃, and standing for 1h to obtain the FPC board for detection;

s7, exposing with ORM-2317-F-00 exposure machine at 100mJ/cm²Irradiating the FPC board for detection by the energy until the photosensitive film is cured to form a photoresist dry film;

s8, the uncured portion of the photosensitive film was washed with a sodium carbonate solution having a mass fraction of 1%, to obtain a resist pattern.

Performance test

And (3) resolution detection:

the FPC board for detection in S6 was exposed to light using a scattered light exposure machine using an LED lamp having a wavelength of 405nm, and the exposure amount was an exposure amount that remained at 29 levels using an exposure ruler of 41 levels. Using a negative film for inspection having a standard resolution, a wiring pattern having a line width of 400 μm and a thickness of 30 μm was closely attached and exposed to a prescribed exposure amount; after exposure, the PET film was peeled off, and an aqueous solution of sodium carbonate of 1% concentration was sprayed at 30 ℃ for 100 seconds to remove the unexposed portion; the resolution is represented by the residual linearity (μm) of the developing solution without peeling off, and the smaller the value of the residual linearity, the higher the resolution is, the thinner the copper foil is not peeled off. The results are shown in Table 3.

Detecting the developability:

in the above-described resolution detection, the developability was detected by observing the substrate after the unexposed portion: if no photoresist residue is observed, marking as 'A'; photoresist residue, denoted as "B", was observed and the results are shown in table 3.

And (3) flexibility detection:

by using O₂RiE etching the resist pattern of S8, then laminating another photosensitive film on the resist pattern, repeating S7 to S8 to obtain a laminated plate for inspection; the laminated plate for detection is soaked in a soldering tin bath at 260 ℃ for 10s, soldering tin treatment is carried out, then, the cracking condition during bending is observed by naked eyes, and if no cracking occurs, the laminated plate is marked as 'good'; if cracks occur. The results are reported as "poor" in Table 3.

And (3) detecting the gel rate:

weighing 50g of photoresist, pouring the photoresist into a special polytetrafluoroethylene mold groove with the length of 10mm, the width of 10mm and the depth of 1.5mm to prepare a detection mold 1; preparing a detection mold 2 by the same method; respectively irradiating detection mode 1 and detection mode 2 with 405nm wavelength LED light at room temperature with irradiation energy of 15mW/cm²The irradiation time of the detection mold 1 is 20s, the irradiation time of the detection mold 2 is 40s, the irradiated photoresist sample is wrapped by filter paper, then acetone is used for extraction in a Soxhlet extractor for 2h, the filter paper is taken out and dried until the weight of the filter paper is constant, the residual solid mass is weighed, and the gel fraction of the photoresist is calculated.

Detection method/test method

TABLE 3

The present application is further described below in conjunction with table 3.

With the combination of examples 1-7 and comparative example 1, the gel fraction of examples 1-7 is much higher than that of comparative example 1, because C absorbs the irradiated light and initiates photopolymerization of A when the photoresist is cured; d and A are subjected to nucleophilic addition reaction in the polymerization process of A, so that the cross-linking degree of the reaction is increased, the rapid curing of the photoresist at the edge of a light spot is facilitated, and the gel rate of the photoresist is further improved; after the polymerization of the D and the A, the thickness of the photosensitive film is increased, and the resolution of the photoresist is reduced; b, under the action of illumination, polymers in the photoresist are degraded into small molecular substances, and the small molecular substances are volatilized from the photosensitive film, so that the thickness of the photosensitive film is reduced, and the resolution of the photoresist is increased; but B is susceptible to air oxidation failure; e has stronger reducibility and plays a role in protecting B.

The B, D, E of the present application cooperate to provide the photoresist with excellent low energy curing properties while increasing the resolution of the photosensitive film.

In the case of combining example 4 and comparative example 2, the composition D was not contained in comparative example 2, and when the photoresist at the edge of the light spot was cured, the curing rate of the photoresist was slow by addition polymerization of A alone, thereby making the gel fraction of the photoresist small.

In combination with example 4 and comparative example 3, B promotes the degradation of the polymer in the photoresist to small molecular substances, which volatilize from the photosensitive film, so that the thickness of the photosensitive film is reduced and the resolution of the photoresist is increased.

Combining example 4 and comparative example 3, B is rich in Si element in O₂-RiE Oxidation of Si to SiO during etching₂，SiO₂And a thin layer is formed on the surface of the photoresist to protect the photoresist, so that the photosensitive film B can be laminated on the same substrate in multiple layers, and the formed laminated body has excellent flexibility and is suitable for manufacturing FPC boards.

Combining example 4 and comparative example 4, comparative example 4 does not contain component E, B is easily oxidized by air, and is difficult to promote the decomposition of the polymer under the irradiation of light, so that the thickness of the photosensitive film is larger after D and A are crosslinked, and the resolution of the photoresist is reduced.

By combining the embodiment 4 and the comparative embodiments 1-2, the molecular weight of A in the comparative embodiment 1 is too large, the steric hindrance during polymerization is large, so that the photoresist is difficult to cure, and the gel rate of the photoresist is reduced; in comparative example 2, the molecular weight of a is too small, and small-molecule polymer impurities are easily formed during the curing process of the photoresist, thereby reducing the resolution of the photoresist.

With the combination of the embodiment 4 and the embodiments 8-13, compared with oxime ester photoinitiators, the ferrocene photoinitiator has higher light absorption intensity at a wavelength of 405nm and higher initiation activity, and is beneficial to rapidly initiating photopolymerization of A and D, so that the gel fraction of the photoresist is improved.

With reference to examples 8 to 10 and examples 11 to 13, compared with ferrocene, ferrocene carboxylic acid N-succinimidyl ester has a larger conjugated system and stronger light absorption activity of intramolecular cyclopentadiene, so that the curing rate of the photoresist is further increased, and the gel fraction of the photoresist is improved.

The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.

Claims

1. The low-energy-cured photoresist is characterized by comprising the following components in parts by weight:

2. A low energy curable photoresist according to claim 1 wherein: the photoresist comprises the following components in parts by weight:

3. A low energy curable photoresist according to claim 1 wherein: the B is selected from polysilane oligomer, and the molecular weight of the B is 1100-1800.

4. A low energy curable photoresist according to claim 1 wherein: the molecular weight of A is 88 w-109 w.

5. A low energy curable photoresist according to claim 3 wherein: and the C is oxime ester photoinitiator or ferrocene photoinitiator.

6. The low energy curable photoresist of claim 5, wherein: the ferrocene photoinitiator adopts carbonyl modified ferrocene.

7. A resist pattern, characterized by: the resist pattern is mainly made of the photoresist of any one of claims 1 to 6.

8. A method for producing a resist pattern according to claim 7, comprising the steps of:

in a vacuum environment, controlling the temperature to be 50-70 ℃ and the pressure to be 0.3-0.5 Mpa, and connecting the photosensitive film to the FPC substrate in a pressing manner;