A low-etch-rate metal photoresist stripping solution composition and its application

Abstract

This invention discloses a low-etch-rate photoresist stripping solution composition, comprising the following raw materials in weight percentages: 65-75 wt% aromatic hydrocarbon solvent, 20-35 wt% acetamide, 0.1-1 wt% metal corrosion inhibitor, 0.1-5 wt% solubilizer, and 0.1-5 wt% chelating agent. This invention also discloses the application of the aforementioned low-etch-rate photoresist stripping solution composition. The photoresist stripping solution provided by this invention exhibits a low etching rate on the substrate metal on wafers and is compatible with removing most types of positive and negative photoresists available on the market.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and more particularly to a photoresist stripping solution composition and its application. Background Technology

[0002] Wafer manufacturing primarily relies on photolithography to achieve high-resolution, high-density patterning processes, thereby forming complex circuits layer by layer on the wafer surface. Photolithography is a micro-nano fabrication process that uses photosensitive materials under visible light, ultraviolet light, or electron beams to transfer patterns from a photomask to a substrate through processes such as exposure, development, and etching.

[0003] There are two methods for removing photoresist from wafers: wet stripping and dry stripping. Wet stripping uses specific chemicals to dissolve the photoresist, thereby cleaning away photoresist residue. Dry stripping uses oxygen in a plasma state, known as an ashing component, to ashing and remove the photoresist residue remaining on the wafer surface.

[0004] Current methods for removing photoresist residue and byproducts primarily employ wet stripping, which uses a photoresist stripping solution containing acetone to remove the positive photoresist. Existing photoresist stripping solutions mainly consist of organic bases / acids, polyols, and metal corrosion inhibitors, and are divided into acidic and alkaline systems.

[0005] After wafer etching, it is necessary to clean the photoresist from the wafer surface and remove the etching byproducts from the small holes formed after etching. Based on their chemical reaction mechanism and development principle, photoresist can be divided into two categories: negative photoresist and positive photoresist. Negative photoresist forms an insoluble substance after exposure to light; conversely, positive photoresist is insoluble in certain solvents but becomes soluble after exposure to light. Current wet stripping methods use two types of photoresist stripping solutions: one is a positive photoresist stripping solution, used to remove positive photoresist and its corresponding byproducts; the other is a negative photoresist stripping solution, used to remove negative photoresist and its corresponding byproducts.

[0006] Chinese patent document (CN110262199A) discloses a photolithography negative resist stripping solution, the raw materials of which include the following components by mass fraction: 1.00%-5.00% quaternary ammonium base, 5.00%-40.00% alkanolamine, 0.10%-8.00% corrosion inhibitor, 10.00-30.00% linear amide organic solvent, 5.00-25.00% sulfone and / or sulfoxide organic solvent, 15.00%-30.00% alcohol ether organic solvent, 5.00%-15.00% alkyl ketone organic solvent, 0.01%-2.00% PO-EO-vinyl diamine copolymer and the balance being water, the sum of the mass fractions of each component being 100%, wherein the PO-EO-vinyl diamine copolymer is one or more of Tetronic 1107, Tetronic 1301 and Tetronic 1307.

[0007] Existing photoresist stripping solutions generally cannot directly remove negative photoresist. Some negative photoresist stripping solutions can remove positive photoresist, but they corrode the substrate metal on the wafer while removing the positive photoresist. This results in existing photoresist stripping solutions being single-function and unable to simultaneously remove both positive and negative photoresist. During wafer cleaning, only corresponding single-function photoresist stripping solutions can be used, requiring users to purchase multiple solutions, leading to excessively high wafer stripping costs. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a photoresist stripping liquid composition that has a low etching rate on the substrate metal on the wafer and can quickly strip the positive and negative photoresist.

[0009] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a metal low etch rate photoresist stripping solution composition, comprising the following raw materials in weight percentages: 65-75 wt% aromatic hydrocarbon solvent, 20-35 wt% acetamide, 0.1-1 wt% metal corrosion inhibitor, 0.1-5 wt% solubilizer and 0.1-5 wt% chelating agent.

[0010] The metal corrosion inhibitor is a five-membered heterocyclic compound containing four nitrogen atoms, and is selected from at least one of 5-mercaptotetrazole, 5-benzyltetrazole, 1-methyl-5-mercaptotetrazole, m-aminophenyltetrazole and 1-phenyl-5-mercaptotetrazole.

[0011] The solubilizer is at least one of fatty acid methyl ester polyoxyethylene ether, sorbitan monosilicone, polyoxyethylene sorbitan monooleate, and polyoxyethylene sorbitan dioleate.

[0012] The chelating agent is one of methanesulfonic acid and diethylenetriamine.

[0013] Preferably, the photoresist stripping solution composition comprises the following raw materials in weight percentages: 73-75 wt% aromatic hydrocarbon solvent, 24-26 wt% acetamide, 0.2-0.4 wt% metal corrosion inhibitor, 0.3-0.5 wt% solubilizer and 0.2-0.4 wt% chelating agent.

[0014] Preferably, the photoresist stripping solution composition comprises the following raw materials in weight percentages: 75 wt% aromatic hydrocarbon solvent, 24 wt% acetamide, 0.3 wt% metal corrosion inhibitor, 0.3 wt% solubilizer, and 0.4 wt% chelating agent.

[0015] Preferably, the metal corrosion inhibitor further includes benzotriazole, wherein the metal corrosion inhibitor is a combination of benzotriazole and one of 5-mercaptotetrazole, 5-benzyltetrazole, 1-methyl-5-mercaptotetrazole, m-aminophenyltetrazole, and 1-phenyl-5-mercaptotetrazole. Tetraazoles can produce a synergistic effect with benzotriazole, with the tetraazole as the main component of the metal corrosion inhibitor and benzotriazole as the synergist.

[0016] Preferably, the combination ratio of benzotriazole with any one of 5-mercaptotetrazole, 5-benzyltetrazole, 1-methyl-5-mercaptotetrazole, m-aminophenyltetrazole and 1-phenyl-5-mercaptotetrazole is 1:1.

[0017] Preferably, the metal corrosion inhibitor further includes imidazole, wherein the metal corrosion inhibitor is a combination of imidazole and one of 5-mercaptotetrazole, 5-benzyltetrazole, 1-methyl-5-mercaptotetrazole, m-aminophenyltetrazole, and 1-phenyl-5-mercaptotetrazole. Tetraazoles can produce a synergistic effect with imidazole, with the tetraazole as the main component of the metal corrosion inhibitor and the imidazole as the synergist.

[0018] Preferably, the ratio of imidazole to one of 5-mercaptotetrazole, 5-benzyltetrazole, 1-methyl-5-mercaptotetrazole, m-aminophenyltetrazole, and 1-phenyl-5-mercaptotetrazole is 1:1.

[0019] Preferably, the aromatic hydrocarbon solvent is obtained by distillation and purification of petroleum at 150°C. This allows for the purification of benzene ring compounds containing nonpolar molecules.

[0020] The present invention also provides an application of a metal low etch rate photoresist stripping liquid composition, wherein the metal low etch rate photoresist stripping liquid composition is used to remove positive and negative photoresist.

[0021] The aforementioned low-etch-rate photoresist stripping solution composition can simultaneously remove both positive and negative photoresist, with the removal time for positive photoresist being shorter than that for negative photoresist. Therefore, during stripping, wafers containing different photoresists can be immersed in the photoresist stripping solution of this invention, and then the different wafers can be removed in batches according to time intervals.

[0022] A current photoresist stripping solution containing sodium dodecyl octylbenzenesulfonate can simultaneously remove residual photoresist from most types of positive photoresist and some types of negative photoresist, causing only slight corrosion to the metal substrate. However, because it is an acidic system, it is incompatible with most metal corrosion inhibitors. Even after using suitable partial corrosion inhibitors, the etching rate of the metal on the wafer remains high. The inventors modified it to an alkaline system, retaining the original aromatic hydrocarbon solvent and chelating agent, and re-formulated a metal corrosion inhibitor and solubilizer compatible with organic bases. Among the organic bases, acetamide is relatively weakly alkaline, and the pH value of the formulated photoresist stripping solution is around 11.8, with fewer OH- ions in the solution, resulting in less corrosive effect on the metal under a weakly alkaline environment. However, the removal time for negative photoresist is relatively long, requiring 30 minutes to completely remove it.

[0023] This invention employs an alkaline system, combined with an aromatic hydrocarbon solvent and a chelating agent, as well as a metal corrosion inhibitor and solubilizer compatible with organic bases. This invention selects a four-membered nitrogen ring compound metal corrosion inhibitor and uses two metal corrosion inhibitors that work synergistically, significantly reducing the time required to remove photoresist.

[0024] The dissolution process of the photoresist in the stripping solution of this invention is as follows: the organic solvent (aromatic hydrocarbon solvent) in the stripping solution comes into contact with the photoresist outer layer (molecular chain unentangled resin layer), causing the photoresist outer layer to fully swell and soften, allowing the photoresist residue to detach from the wafer. Acetamide reacts with the photoresist, transforming it into a small molecule structure that is easier to remove. This small molecule structure is more soluble in organic solvents than the large molecule structure, thus significantly shortening the photoresist removal time. In an alkaline environment, metals are prone to corrosion. Metal corrosion inhibitors can donate electrons to the empty orbitals of metal atoms, stabilizing them and allowing them to adsorb onto the metal surface under the influence of complexing bonds, forming a molecular protective film. Tetraazole is a five-membered nitrogen-containing heterocycle, and its structure is very stable under ring strain. It also has a high nitrogen content, with four nitrogen atoms on the nitrogen ring, enabling it to donate a large number of electrons to the metal. Its nitrogen content is much higher than other azoles, resulting in extremely strong adsorption capacity for metals. It is an effective metal corrosion inhibitor, requiring only a small amount to significantly reduce the etching rate of the metal. Chelating agents can further reduce the amount of metal dissolved in the stripping solution and prevent scaling on the metal lines on the wafer.

[0025] Compared with existing technologies:

[0026] (1) The photoresist stripping solution of the present invention can remove most types of positive or negative photoresist on the wafer surface, and can also remove mixed residual photoresist on the wafer surface using positive / negative double-layer photolithography.

[0027] (2) The photoresist stripping solution of the present invention can remove positive photoresist residue within 9 minutes and negative photoresist residue within 23 minutes at a temperature of 80°C. The heating equipment requirements are low; a water bath can be used for heating, resulting in low energy consumption.

[0028] (3) The photoresist stripping solution of the present invention uses a variety of metal corrosion inhibitors with synergistic effects, which can effectively protect the metal substrate from corrosion and cause minimal damage to the metal circuits on the wafer.

[0029] The photoresist stripping composition of the present invention is compatible with the removal of both positive and negative photoresist, has a low etching rate on the substrate metal on the wafer, and can quickly strip both positive and negative photoresist. Detailed Implementation

[0030] To fully understand the purpose, features and effects of the present invention, the technical solution of the present invention will be further described below with reference to the embodiments, but the scope of protection of the present invention is not limited to the following embodiments.

[0031] The metal low etch rate photoresist stripping solution composition of the present invention is composed of the following raw materials in weight percentage: 65-75 wt% aromatic hydrocarbon solvent, 20-35 wt% acetamide, 0.1-1 wt% metal corrosion inhibitor, 0.1-5 wt% solubilizer and 0.1-5 wt% chelating agent. All wt% mentioned in the present invention refers to the mass percentage content.

[0032] The following weight percentages of raw materials are placed in a container and mixed evenly by stirring, shaking, etc., to prepare the photoresist stripping solution of Examples 1-13, with a total volume of 100ml for each example.

[0033] Example 1: 65 wt% aromatic hydrocarbon solvent, 34 wt% acetamide, 0.1 wt% m-aminophenyltetrazole, 0.45 wt% fatty acid methyl ester polyoxyethylene ether, 0.45 wt% methanesulfonic acid.

[0034] Example 2: 75 wt% aromatic hydrocarbon solvent, 24 wt% acetamide, 0.1 wt% m-aminophenyltetrazole, 0.45 wt% fatty acid methyl ester polyoxyethylene ether, 0.45 wt% methanesulfonic acid.

[0035] Example 3: 75 wt% aromatic hydrocarbon solvent, 24 wt% acetamide, 0.3 wt% m-aminophenyltetrazole, 0.1 wt% fatty acid methyl ester polyoxyethylene ether, 0.6 wt% methanesulfonic acid.

[0036] Example 4: 74.1 wt% aromatic hydrocarbon solvent, 24 wt% acetamide, 1 wt% m-aminophenyltetrazole, 0.45 wt% fatty acid methyl ester polyoxyethylene ether, 0.45 wt% methanesulfonic acid.

[0037] Example 5: 70.45 wt% aromatic hydrocarbon solvent, 24 wt% acetamide, 0.3 wt% m-aminophenyltetrazolium, 5 wt% fatty acid methyl ester polyoxyethylene ether, 0.25 wt% methanesulfonic acid.

[0038] Example 6: 75 wt% aromatic hydrocarbon solvent, 24 wt% acetamide, 0.3 wt% m-aminophenyltetrazole, 0.3 wt% fatty acid methyl ester polyoxyethylene ether, 0.4 wt% methanesulfonic acid.

[0039] Example 7: 75 wt% aromatic hydrocarbon solvent, 24 wt% acetamide, 0.3 wt% m-aminophenyltetrazole, 0.3 wt% sorbitan monosilicate, 0.4 wt% methanesulfonic acid.

[0040] Example 8: 75 wt% aromatic hydrocarbon solvent, 24 wt% acetamide, 0.3 wt% m-aminophenyltetrazolium, 0.3 wt% polyoxyethylene sorbitan dioleate, 0.4 wt% methanesulfonic acid.

[0041] Example 9: 75 wt% aromatic hydrocarbon solvent, 24 wt% acetamide, 0.3 wt% m-aminophenyltetrazole, 0.3 wt% a mixture of fatty acid methyl ester polyoxyethylene ether and polyoxyethylene sorbitan monooleate, and 0.4 wt% methanesulfonic acid.

[0042] Example 10: 75 wt% aromatic hydrocarbon solvent, 24 wt% acetamide, 0.2 wt% 5-benzyltetrazole, 0.1 wt% benzotriazole, 0.3 wt% fatty acid methyl ester polyoxyethylene ether, 0.4 wt% methanesulfonic acid.

[0043] Example 11: 75 wt% aromatic hydrocarbon solvent, 24 wt% acetamide, 0.15 wt% 5-benzyltetrazole, 0.15 wt% benzotriazole, 0.3 wt% fatty acid methyl ester polyoxyethylene ether, 0.4 wt% methanesulfonic acid.

[0044] Example 12: 75 wt% aromatic hydrocarbon solvent, 24 wt% acetamide, 0.2 wt% 5-benzyltetrazole, 0.1 wt% imidazole, 0.3 wt% fatty acid methyl ester polyoxyethylene ether, 0.4 wt% methanesulfonic acid.

[0045] Example 13: 75 wt% aromatic hydrocarbon solvent, 24 wt% acetamide, 0.15 wt% 5-benzyltetrazole, 0.15 wt% imidazole, 0.3 wt% fatty acid methyl ester polyoxyethylene ether, 0.4 wt% methanesulfonic acid.

[0046] The wafer coated with photoresist and after development and etching is cut into 3cm*3cm pieces, and the pieces are immersed in the photoresist stripping solution provided in this invention.

[0047] Test procedure: First, copper sheets with photoresist were placed in Examples 1-6 and heated to 80℃. The color of the silver surface of the stripping solution was observed to confirm whether there was a significant color change (i.e., to confirm the metal dissolution). The etched thickness of the copper sheet and the photoresist removal were observed using a four-point probe thickness gauge and an electron microscope, respectively. Among them, the copper sheet in Example 6 had the lowest etched thickness and the photoresist was removed most cleanly.

[0048] Analysis of Comparative Examples 1, 2, and 6 revealed that (Examples 1 and 2 were used as comparative examples) 24-26 wt% acetamide and 73-75 wt% aromatic hydrocarbon solvents exhibited lower corrosion rates on metals when removing positive / negative photoresist.

[0049] Analysis of comparisons of Examples 2, 4, and 6 (Examples 2 and 4 are comparative examples) revealed that within the range of 0.1-0.3 wt%, the corrosion rate of the metal significantly decreased with increasing metal corrosion inhibitor concentration. Beyond this range, the increase was not significant. A metal corrosion inhibitor concentration of 0.2-0.4 wt% effectively protected the metal on the wafer.

[0050] As shown in Table 1, after comparing Examples 3, 5, and 6 (Examples 3 and 5 are used as comparative examples), it was found that 0.2-0.4 wt% of solubilizer can accelerate the removal speed of photoresist positive / negative resist. Beyond this content, the removal speed of photoresist positive / negative resist is not significantly improved. The photoresist stripping solution with this solubilizer content requires 9 minutes to remove photoresist positive resist and 26 minutes to remove photoresist negative resist.

[0051] Table 1

[0052]

[0053] Since Example 6 is the best example among Examples 1-6, different components of the solubilizer are tested based on it. Further tests revealed that the minimum reaction time is 23 minutes, which can ensure that the photoresist is completely removed, as shown in Table 2.

[0054] Table 2

[0055]

[0056] Since Example 6 is the best example among Examples 1-6, the synergistic effect of two or more metal corrosion inhibitors is now tested based on it. The experimental method is to change the metal corrosion inhibitor from a single component to a compound component. The results are shown in Table 3.

[0057] Table 3

[0058]

[0059] Tests revealed that benzotriazole exhibited the best corrosion inhibition effect on metals when combined with one of the following: 5-mercaptotetrazole, 5-benzyltetrazole, 1-methyl-5-mercaptotetrazole, m-aminophenyltetrazole, and 1-phenyl-5-mercaptotetrazole, in a 1:1 ratio.

[0060] in The area within this range is free from corrosion. Slight corrosion. Moderate corrosion. The above are cases of severe corrosion. (Equal to 0.1 nanometers).

[0061] Based on the photoresist stripping solution shown in Example 11, the etching rates of different metals were then investigated. Tests were conducted at temperatures of 60℃, 70℃, and 80℃ for 20 minutes each. Silicon wafers coated with aluminum, copper, silver, titanium, and nickel were purchased and cut into 3cm x 3cm pieces. Three pieces of each metal were used for testing, and the etching thickness of each metal wafer was measured at 60℃, 70℃, and 80℃ under the conditions described in this invention. The total etching thickness was measured using a four-point probe and then divided by the total time to obtain the etching rate per unit time. The results are shown in Table 4. It can be seen that the etching rate of metals using this invention is relatively low.

[0062] Table 4

[0063] temperature aluminum copper silver titanium nickel 60℃ 0.23 1.36 0.43 0.31 0.75 70℃ 0.25 1.43 0.62 0.30 0.65 80℃ 0.28 1.55 0.56 0.36 0.71

[0064] "Positive / Negative Dual-Layer Photolithography" refers to a photolithography process in which a thin layer of negative photoresist is coated on a thick layer of positive photoresist, forming an overhanging, roof-like structure at the edge of the photoresist layer. The photoresist residue left after this process consists of one layer of negative photoresist and one layer of positive photoresist. Conventional photoresist stripping solutions can only remove one type of photoresist, thus failing to completely remove the residue. This invention, however, can completely remove both types of photoresist.

[0065] The photoresist stripping solution of the present invention is compatible with removing both positive and negative photoresist. Therefore, during the stripping process, wafers containing different photoresists can be immersed in the photoresist stripping solution of the present invention, and then the different wafers can be removed in batches according to time.

[0066] This invention is applicable to the removal of Ruihong brand negative photoresist series and KrF photoresist series, as well as Jingrui brand positive photoresist series and negative photoresist series. It also has good compatibility with other brands of photoresists on the market.

[0067] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A metal low etch rate photoresist stripping solution composition, characterized in that, The photoresist stripping solution composition comprises the following raw materials in weight percentages: 73-75 wt% aromatic hydrocarbon solvent, 24-26 wt% acetamide, 0.2-0.4 wt% metal corrosion inhibitor, 0.3-0.5 wt% solubilizer and 0.2-0.4 wt% chelating agent; The metal corrosion inhibitor is a five-membered heterocyclic compound containing four nitrogen atoms, and is selected from at least one of 5-mercaptotetrazole, 1-methyl-5-mercaptotetrazole, 5-benzyltetrazole, m-aminophenyltetrazole and 1-phenyl-5-mercaptotetrazole. The metal corrosion inhibitor further includes benzotriazole, which is a combination of benzotriazole with any one of 5-mercaptotetrazole, 5-benzyltetrazole, 1-methyl-5-mercaptotetrazole, m-aminophenyltetrazole, and 1-phenyl-5-mercaptotetrazole; the combination ratio of benzotriazole with any one of 5-mercaptotetrazole, 5-benzyltetrazole, 1-methyl-5-mercaptotetrazole, m-aminophenyltetrazole, and 1-phenyl-5-mercaptotetrazole is 1:

1. Alternatively, the metal corrosion inhibitor further includes imidazole, wherein the metal corrosion inhibitor is a combination of imidazole and any one of 5-mercaptotetrazole, 5-benzyltetrazole, 1-methyl-5-mercaptotetrazole, m-aminophenyltetrazole, and 1-phenyl-5-mercaptotetrazole; the combination ratio of imidazole to any one of 5-mercaptotetrazole, 5-benzyltetrazole, 1-methyl-5-mercaptotetrazole, m-aminophenyltetrazole, and 1-phenyl-5-mercaptotetrazole is 1:

1. The solubilizer is at least one of fatty acid methyl ester polyoxyethylene ether, sorbitan monosodium silicate, polyoxyethylene sorbitan monooleate and polyoxyethylene sorbitan dioleate. The chelating agent is one of methanesulfonic acid and diethylenetriamine.

2. The metal low-etch-rate photoresist stripper composition according to claim 1, wherein The photoresist stripping solution composition comprises the following raw materials in weight percentages: 75 wt% aromatic hydrocarbon solvent, 24 wt% acetamide, 0.3 wt% metal corrosion inhibitor, 0.3 wt% solubilizer, and 0.4 wt% chelating agent.

3. The metal low-etch-rate photoresist stripper composition of claim 1, wherein The aromatic hydrocarbon solvent is obtained by distillation and purification of petroleum at 150°C.

4. Use of a metal low-etching rate photoresist stripping liquid composition, characterized by, The metal low etch rate photoresist stripping solution composition as described in any one of claims 1 to 3 is used to remove positive and negative photoresist.

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