CN116120998B

CN116120998B - Flushing composition and photoresist pattern forming method thereof

Info

Publication number: CN116120998B
Application number: CN202310407132.5A
Authority: CN
Inventors: 李永斌; 陈志鹏; 黄玉伟; 魏玉凤
Original assignee: Gansu Hualong Core Material Technology Co ltd
Current assignee: Gansu Hualong Core Material Technology Co ltd
Priority date: 2023-04-17
Filing date: 2023-04-17
Publication date: 2023-06-16
Anticipated expiration: 2043-04-17
Also published as: CN116120998A

Abstract

The present invention relates to a rinse composition and a photoresist pattern forming method thereof. The rinse composition comprises a fluorosurfactant, a water soluble material containing hydroxyl groups, and water. The composition is suitable for the rinsing process of the photoresist pattern after photoetching development, prevents collapse and defect generation of the photoresist pattern, and is used for further improving the pattern resolution.

Description

Flushing composition and photoresist pattern forming method thereof

Technical Field

The present invention relates to the field of photoresist technology, and more particularly, to a photolithography process in semiconductor device fabrication.

Background

The photoetching process plays a crucial role in the manufacture of semiconductor chips and mainly comprises the steps of photoresist spin coating, exposure, development, cleaning and the like. The photoetching process before 28nm, after development, the ultra-pure water is directly used for spin-drying treatment, and then the next working procedure can be carried out. However, with the rapid improvement of technology nodes and integration level, the extreme miniaturization of patterns not only puts higher demands on the performance of photoresist, but also makes more stringent demands on the developed photoresist patterns. Especially, the process nodes of 28nm and below are easy to cause defects due to collapse of photoresist patterns along with extremely shrinking line width and increasing depth-to-width ratio, and in addition, the line edge roughness LER (line edge roughness) and the line width roughness LWR (line width roughness) after exposure are also required to be controlled more accurately so as to avoid deterioration of yield.

Disclosure of Invention

In order to further reduce the collapse rate of the photoresist pattern and improve the roughness of the pattern so as to form a finer and complete photoresist pattern, achieve the technical indexes of process requirements and improve the yield and the reliability, the invention provides a flushing composition which comprises a fluorine-containing surfactant, a water-soluble substance containing hydroxyl and water.

Preferably, the fluorine-containing surfactant is selected from perfluoropolyether-based nonionic surfactants, and the chemical structure is as follows:

，

wherein n is 0 or 1, and m is an integer of 22 to 90.

The water-soluble substance containing hydroxyl is one of EO/PO block polyether, polyethylene glycol and high-boiling-point alcohol (namely C5-C10 straight-chain or branched-chain alcohol).

Preferably, the hydroxyl-containing water-soluble material is an Ethylene Oxide (EO)/Propylene Oxide (PO) block polyether (i.e., a propylene glycol block polyether), such as may be commercially available under one or more of the trade designations L35, L45, L64; polyethylene glycol with a molecular weight of preferably 200-600; high boiling alcohols such as one or more of 2-ethylhexanol, heptanol, octanol, nonanol. The water-soluble substance can promote dissolution of the surfactant and reduce foamability of the solution.

The fluorosurfactant is present in an amount of 0.02 to 0.1wt%, preferably 0.05 to 0.1wt%; the content of the water-soluble substance containing hydroxyl groups is 0.01 to 0.1wt%, preferably 0.05 to 0.1wt%.

Optionally, the rinse composition further comprises a compound which prevents the production of bacteria, microorganisms, i.e., a bactericide, in an amount of 0.001 to 0.1wt%, preferably 0.005 to 0.05wt%; the bactericide compound is an isothiazolinone derivative, such as:

2-methyl-4-isothiazol-3-one

;

5-chloro-2-methyl-4-isothiazol-3-one

;

The balance being water.

The invention also provides a method for forming the photoresist pattern, which is characterized in that after the development operation, the composition is used for flushing to remove water-soluble residues on the surface of the photoresist pattern, so as to form a clear and complete photoresist pattern. The method comprises the following steps:

a method of forming a photoresist pattern, comprising:

(1) Spin-coating photoresist on a silicon substrate to form a thin film (which can be set according to the need, for example, can be 0.01-10 mm);

(2) Exposing under a specific light source;

(3) Developing the exposed photoresist to form a specific photoresist pattern;

(4) The developed photoresist pattern was treated with the above-obtained rinse composition.

The method for forming a photoresist pattern as described above, wherein the photoresist is a positive-working chemically amplified photoresist, and the exposure light source has a wavelength of 190-300nm, for example, 248nm.

The method for forming a photoresist pattern as described above, wherein the aspect ratio of the photoresist pattern formed is greater than 3:1 before the treatment with the above-described rinse composition.

The invention has the beneficial effects that:

according to the invention, through designing, the fluorine-containing surfactant with a specific structure is added into the flushing composition, so that the dynamic and static surface tension of wetting liquid can be reduced, the photoresist deformation and breakage caused by capillary phenomenon are eliminated, and the collapse rate is reduced; the water-soluble polymer containing hydroxyl is added, so that the solubilization of the surfactant can be realized, and the solubility and uniformity of the surfactant are improved; the mildew-proof bactericide (such as isothiazolinone derivative) can be added according to the need, and the mildew-proof bactericide can play a role in killing bacteria and fungi by breaking bonds of proteins of the bacteria and the fungi, and can quickly and irreversibly inhibit growth of the bacteria and the fungi to cause death of microbial cells, so that the mildew-proof bactericide has strong inhibition and killing effects on common bacteria, fungi, algae and the like, and can prevent bacteria and mildew from being formed in a high-temperature high-humidity environment. Meanwhile, the rinse composition prevents the influence of capillary phenomenon by changing the surface tension, thereby improving or preventing collapse of the photoresist pattern.

Drawings

In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are used in the description of the embodiments or the prior art will be briefly described, it being obvious that the drawings in the description below are only some embodiments of the invention, and that other drawings can be obtained from these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a microscopic photograph of collapse and defect testing in areas corresponding to the photoresist patterns of examples 1-14;

FIG. 2 is a microscopic image of collapse and defect testing in the region corresponding to the photoresist pattern of comparative example 1;

fig. 3 is a microscopic image of collapse and defect testing in the region corresponding to the photoresist pattern of comparative example 5.

Detailed Description

In order that the above-recited objects, features and advantages of the present invention will be more clearly understood, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description. It should be noted that, in the case of no conflict, the embodiments of the present application and the features in the embodiments may be combined with each other.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced otherwise than as described herein, and therefore the scope of the present invention is not limited to the specific embodiments disclosed below.

Synthesis of hexafluoropropylene oxide dimer and trimer:

adding 50ml of acetonitrile, 50ml of tetraethylene glycol dimethyl ether and 5g of dried KF into a 1L polymerization kettle, uniformly stirring and mixing, replacing air in a reaction system with nitrogen, setting the temperature to 15 ℃ and stabilizing, introducing 1000g of hexafluoropropylene oxide, recovering to normal pressure, stopping stirring after the reaction is finished, and recovering to room temperature to obtain a mixture. Standing and layering the mixture, collecting a lower layer liquid, filtering to obtain a perfluoropolyether acyl fluoride mixture with different polymerization degrees, and carrying out distillation, separation and purification on the mixture to obtain hexafluoropropylene oxide dimer and trimer with single polymerization degree, wherein the purity is larger than or equal to 99%.

Synthesis of F1:

under the protection of nitrogen, 10g (0.01 mol) of dried polyethylene glycol (1000), 1.01g (0.01 mol) of anhydrous triethylamine and 80mL of anhydrous tetrahydrofuran are added into a dry three-neck flask, the temperature is constant and is 55 ℃, after magnetic stirring is completed, 7.304g (0.022 mol) of hexafluoropropylene oxide dimer is slowly added dropwise, after the dropwise addition is completed, the temperature is kept for stirring and reacting for 20 hours, the obtained product is filtered by alkaline alumina for three times, then precipitated in normal hexane, filtered, and the solid is dried in vacuum at 60 ℃ to obtain the compound with the F1 structure.

The synthesis method of F2, F3 and F4 is the same as that of the above, and the specific dosage ratio is shown in the following table 1.

TABLE 1 molar ratio of F1 to F4 synthetic raw materials

The rinse composition is obtained from the above-mentioned fluorosurfactants F1 to F4, a water-soluble substance containing a hydroxyl group and water, and a bactericide which may be contained.

Wherein the water-soluble substances containing hydroxyl groups are Ethylene Oxide (EO)/Propylene Oxide (PO) block polyether (propylene glycol block polyether) and polyethylene glycol (with molecular weight of 200-600); the high boiling point alcohols (C5-C10 straight chain or branched chain alcohols) are specifically shown as structures A1-A6 and the like.

The bactericide is 2-methyl-4-isothiazol-3-one or 5-chloro-2-methyl-4-isothiazol-3-one; specifically, the structures B1 and B2 are shown.

The method for forming the photoresist pattern on the silicon wafer comprises the following steps: the method comprises the steps of spin coating a bottom anti-reflection coating material and a photoresist material on a silicon wafer, baking to form a film (which can be set according to the requirement, for example, can be 0.01-10 mm), exposing the film by using a KrF ultraviolet light source (wavelength is 248 nm) or an electron beam light source, and then developing the exposed photoresist film by using a developing solution to form a photoresist pattern with an aspect ratio of 5:1 (only an example is shown here, the aspect ratio is more than 3:1), and further treating the photoresist pattern by using a flushing composition corresponding to the method in Table 2. Finally, a photoresist pattern is formed, the collapse rate and defects of the pattern are obviously improved, and the specific test results are shown in table 2.

Foaming test method: according to examples 1 to 14, 60mL of the solution was prepared in each of comparative examples 1 to 5 in a 100mL vial, the vial was shaken for 10 seconds, and then left to stand for observation of the foam disappearance time, and the time from the start of shaking until the foam completely disappeared was recorded.

Collapse rate and defect number test: and placing the rinsed and spin-dried silicon wafer under a microscope to observe the collapse (bonding and twisting) and defect (defect comprises disappearance of the pattern in the area and defect of the pattern itself) of the photoresist pattern, recording the number of the collapse and defect in the observation area, and measuring a plurality of positions of the silicon wafer respectively to average.

TABLE 2 collapse Rate of Photoresist Pattern and Defect test results

Foamability evaluation:

a: almost no foam is generated when shaking;

b: a small amount of foam was generated when shaking, and disappeared after 60 s;

c: a small amount of foam was generated when shaking, and disappeared after 300 s;

and (3) collapse rate evaluation:

a: the pattern is perfect;

b: the pattern has less collapse and bonding phenomena;

c: the pattern has collapse bonding phenomenon and distortion;

defect evaluation:

a: the pattern is defect-free;

b: pattern defect rate <1%;

c: the pattern defect rate is 2% -5%.

F1

F2

F3

F4

A1

EO/PO block polyether (brand L64)

A2

（z=4~14）

A3

A4

A5

A6

A7

B1

B2

FIGS. 1-3 are microscopic pictures of collapse and defects in areas of corresponding photoresist patterns of the above-described partial examples and comparative examples of the present invention. From the performance data and the graphs, it can be seen that the rinse compositions of examples 1 to 14 can well prevent collapse and defects of the photoresist patterns, and the pattern lines are intact; in comparative example 1, only pure water was used as the rinse liquid, and pattern collapse and defects were serious, as shown in fig. 2 in particular; compared with the example 2, the comparative examples 2 and 3 have the advantages that when no or less hydroxyl-containing water-soluble substances are added, the dissolubility and uniformity of the surfactant in the flushing liquid are poor, the corresponding foam inhibition effect is not achieved, the collapse phenomenon is caused, and the effect of inhibiting the collapse and defects of the photoresist pattern is not effectively achieved; comparative example 4, compared with example 2, the surface tension of the rinse liquid increased with the decrease in the amount of the surfactant, failed to exert the effect of preventing collapse and defects, and caused not only collapse and adhesion of the pattern but also defects, even missing, of the pattern; comparative example 5 is inferior to example 2 in that the ethanol has a weak foam suppressing property, so that the fine bubbles in the rinse liquid cannot be effectively removed, and the collapse preventing and defect preventing effects are deteriorated, as shown in fig. 3.

It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. While still being apparent from variations or modifications that may be made by those skilled in the art are within the scope of the invention.

Claims

1. A rinse composition comprising a fluorosurfactant, a water soluble material comprising hydroxyl groups, and water;

the fluorine-containing surfactant is a perfluoropolyether-based nonionic surfactant, and the chemical structure is as follows:

，

wherein n is 0 or 1, m is an integer from 22 to 90;

the water-soluble substance containing hydroxyl is one of EO/PO block polyether, polyethylene glycol and C5-C10 straight chain or branched alcohols;

wherein the molecular weight of the polyethylene glycol is 200-600; the C5-C10 straight chain or branched chain alcohol is one or more of 2-ethylhexanol, heptanol, octanol and nonanol;

the fluorosurfactant is present in the rinse composition in an amount of 0.02 to 0.1wt%; the water-soluble substance containing hydroxyl groups is contained in the flushing composition in an amount of 0.01 to 0.1wt%.

2. The rinse composition of claim 1, further comprising a biocide.

3. A method of forming a photoresist pattern, comprising:

(1) Spin-coating photoresist on a silicon substrate to form a film;

(2) Exposing under a specific light source;

(3) Developing the exposed photoresist to form a specific photoresist pattern;

(4) Treating the developed photoresist pattern with a rinse composition of any one of claims 1-2.

4. A method of forming a photoresist pattern according to claim 3, wherein the photoresist is a positive-working chemically amplified photoresist and the exposure light source has a wavelength of 190-300nm.

5. A method of forming a photoresist pattern according to claim 3 or 4, wherein the aspect ratio of the photoresist pattern formed is greater than 3:1 prior to treatment with the rinse composition of any of claims 1-2.