Semiconductor photoresist stripping solution and preparation method thereof

Abstract

The application provides a semiconductor photoresist stripping liquid and a preparation method thereof, and relates to the technical field of semiconductor chip manufacturing. The semiconductor photoresist stripping liquid is composed of the following components: organic amine, corrosion inhibitor additive and polar organic solvent. The corrosion inhibitor additive is obtained by mixing isopropyl N-phenyl thiocarbamic acid ester and methyl salicylate. The mass ratio of the isopropyl N-phenyl thiocarbamic acid ester to the methyl salicylate is greater than or equal to 2. The corrosion inhibitor additive is based on the mixing mechanism of isopropyl N-phenyl thiocarbamic acid ester and methyl salicylate, and a protective film formed on the surface of the substrate can make the corrosion rate of the aluminum layer less than or equal to 0.8 Å / min and the corrosion rate of the silver layer less than or equal to 0.5 Å / min, thereby significantly improving the protection effect of the substrate.

Description

Technical Field

[0001] This invention relates to the field of semiconductor chip manufacturing technology, specifically to a semiconductor photoresist stripping solution and its preparation method. Background Technology

[0002] In the semiconductor chip manufacturing process, photoresist is a key material for pattern transfer. After exposure and development, it forms a temporary pattern, which needs to be completely removed by a stripping solution without damaging the substrate material (such as silicon wafer, metal electrode layer (aluminum, copper, titanium), silicon oxide insulating layer, etc.).

[0003] With the development of bump packaging, the requirements for cleaning photoresist residues have also increased. This is mainly due to the increasing number of pins (I / O) per unit area and the growing difficulty in removing photoresist. Therefore, it is essential to develop a cleaning solution with strong photoresist removal capabilities and metal compatibility. Generally, improving the cleaning ability of alkaline photoresist cleaning solutions is achieved by increasing alkalinity, using more effective solvent systems, increasing operating temperature, and extending operating time. However, increasing the alkalinity of the cleaning solution, the operating temperature, and extending the cleaning time often increases corrosion of the metals. Generally, the metals involved in bump packaging are mainly silver, tin, lead, and copper. Existing photoresist stripping solutions have the following technical shortcomings:

[0004] 1. Difficulty in balancing peeling efficiency and corrosion: To improve peeling speed, existing formulations often increase the content of organic amines (more than 50%), resulting in excessive corrosion of metal electrodes and affecting the electrical performance of the device;

[0005] 2. Limited corrosion inhibition effect: Traditional corrosion inhibitors are only effective against a single metal (such as aluminum), and cannot meet the corrosion protection needs of multi-metal composite substrates in semiconductor manufacturing processes.

[0006] Therefore, developing a photoresist stripping solution with high stripping efficiency, low corrosion rate, and compatibility with various substrates has become an urgent need in the semiconductor manufacturing industry. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a semiconductor photoresist stripping solution and its preparation method, which can effectively improve stripping efficiency, reduce corrosion rate, and increase versatility for various substrates.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A semiconductor photoresist stripping solution, by mass percentage, comprises the following components: 30%-40% organic amine, 1%-3% corrosion inhibitor, and the balance being a polar organic solvent.

[0010] The corrosion inhibitor is obtained by mixing isopropyl N-phenyl thiocarbamate and methyl salicylate.

[0011] Preferably, the mass ratio of isopropyl N-phenylthiocarbamate to methyl salicylate is ≥2.

[0012] Preferably, the organic amine is one or more selected from monoethanolamine, ethylamine, n-propylamine, n-butylamine, diethylamine, and di-n-propylamine.

[0013] Preferably, the polar organic solvent is one or more of diethylene glycol monobutyl ether, propylene glycol monobutyl ether, diethylene glycol monomethyl ether, and propylene glycol monomethyl ether.

[0014] The preparation steps of a semiconductor photoresist stripping solution are as follows:

[0015] S1. Take 1 / 2 of the mass of a polar organic solvent and place it in a container. Heat it to 40-50℃, add methyl salicylate, mix well, and obtain solution A.

[0016] S2. Place the remaining polar organic solvent in a container at room temperature, add isopropyl N-phenylthiocarbamate, stir until completely dissolved, add solution A dropwise, mix well to form a mixture, adjust the temperature of the mixture to room temperature, and obtain solution B.

[0017] S3. Add organic amine to solution B and stir until the system is completely homogeneous to obtain solution C;

[0018] S4. Take a sample solution C to test the homogeneity of the system. If it passes the test, filter it to obtain the stripping solution.

[0019] Preferably, the stirring speed in steps S2 and S3 is 300-500 r / min.

[0020] Preferably, the dropping rate in step S2 is 2-3 drops / s.

[0021] Preferably, the filtration accuracy in step S4 is 0.22 μm.

[0022] This invention provides a semiconductor photoresist stripping solution and its preparation method, which has the following advantages compared with the prior art:

[0023] The corrosion inhibitor is based on a mixing mechanism of isopropyl N-phenylthiocarbamate and methyl salicylate, which converts the phenolic hydroxyl group (-OH) of methyl salicylate into an O-aryl thiocarbamate structure. The protective film formed on the substrate surface can reduce the corrosion rate of aluminum layer to ≤0.8 Å / min and silver layer to ≤0.5 Å / min, which is far lower than the industry standard (≤2 Å / min). The photoresist stripping rate is improved by more than 30% compared with existing products. Moreover, the combination of stepwise dissolution and differential temperature drop-addition mixing promotes the preparation of the finished photoresist stripping solution to achieve the expected stripping effect on photoresist within 1-3 minutes, achieving the goal of high stripping efficiency and low corrosion rate. Attached Figure Description

[0024] Figure 1 The image shows the OM (Optical Model) image of the test board after etching with the photoresist stripping solution prepared in Example 1;

[0025] Figure 2 The image shows the OM (Optical Model) image of the test board after etching with the photoresist stripping solution prepared in Example 2;

[0026] Figure 3 The image shows the OM (Optical Model) image of the test board after etching with the photoresist stripping solution prepared in Example 3;

[0027] Figure 4 The OM image of the test board after etching with the photoresist stripping solution prepared in Comparative Example 1;

[0028] Figure 5 The OM image of the test board after etching with the photoresist stripping solution prepared in Comparative Example 2;

[0029] Figure 6 The OM image of the test board after etching with the photoresist stripping solution prepared in Comparative Example 3;

[0030] Figure 7 The OM image of the test board after etching with the photoresist stripping solution prepared in Comparative Example 4;

[0031] Figure 8 The image shows the OM (Optical Marking) pattern of the test board after etching with the photoresist stripping solution prepared in Comparative Example 5. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Preparation of corrosion inhibitors

[0034] Type A corrosion inhibitor: isopropyl N-phenyl thiocarbamate and methyl salicylate are mixed, wherein the mass ratio of isopropyl N-phenyl thiocarbamate to methyl salicylate is 2.

[0035] Type B corrosion inhibitor: Isopropyl N-phenyl thiocarbamate;

[0036] Type C corrosion inhibitor: methyl salicylate;

[0037] Type D corrosion inhibitor: is obtained by mixing isopropyl N-phenyl thiocarbamate and methyl salicylate, wherein the mass ratio of isopropyl N-phenyl thiocarbamate to methyl salicylate is 1.5.

[0038] Example 1

[0039] The stripping fluid consists of the following components by weight percentage: 30% monoethanolamine, 1% type A corrosion inhibitor, and 69% propylene glycol monobutyl ether;

[0040] The preparation method of the stripping fluid is as follows:

[0041] S1. Take 1 / 2 mass of propylene glycol monobutyl ether and place it in a container. Heat it to 45°C, add methyl salicylate, mix well, and obtain solution A.

[0042] S2. Place the remaining propylene glycol monobutyl ether in a container at room temperature, add isopropyl N-phenyl thiocarbamate, stir at 400 r / min until completely dissolved, add solution A dropwise at a rate of 2 drops / s, mix well to form a mixture, adjust the temperature of the mixture to room temperature, and obtain solution B.

[0043] S3. Add monoethanolamine to solution B and stir until the system is completely homogeneous to obtain solution C;

[0044] S4. The homogeneity of the sample solution C system is tested (no stratification, no precipitation). If it passes the test, it is filtered with an accuracy of 0.22μm to obtain the stripping solution.

[0045] Example 2

[0046] The stripping fluid consists of the following components by weight percentage: 40% monoethanolamine, 3% type A corrosion inhibitor, and 57% propylene glycol monobutyl ether;

[0047] The preparation method of the stripping fluid is the same as in Example 1, and all steps are identical.

[0048] Example 3

[0049] The stripping fluid consists of the following components by weight percentage: 30% n-propylamine, 3% type A corrosion inhibitor, and 67% diethylene glycol monomethyl ether;

[0050] The preparation method of the stripping fluid is the same as in Example 1, and all steps are identical.

[0051] Comparative Example 1

[0052] The stripping fluid consists of the following components by weight percentage: 30% monoethanolamine, 1% type B corrosion inhibitor, and 69% propylene glycol monobutyl ether;

[0053] The preparation method of the stripping fluid is the same as in Example 1, except that step S1 is omitted and step S2 is adjusted. The rest are the same. Specifically:

[0054] S2. Place propylene glycol monobutyl ether in a container at room temperature, add isopropyl N-phenylthiocarbamate, and stir at 400 r / min until completely dissolved to obtain solution B.

[0055] Comparative Example 2

[0056] The stripping fluid consists of the following components by weight percentage: 30% monoethanolamine, 1% type C corrosion inhibitor, and 69% propylene glycol monobutyl ether;

[0057] The preparation method of the stripping fluid is the same as in Example 1, except that step S1 is adjusted and step S2 is omitted. The rest are the same. Specifically:

[0058] S1. Place propylene glycol monobutyl ether in a container, heat to 45°C, add methyl salicylate, mix well, and obtain solution B.

[0059] Comparative Example 3

[0060] The stripping fluid consists of the following components by weight percentage: 30% monoethanolamine, 1% type D corrosion inhibitor, and 69% propylene glycol monobutyl ether;

[0061] The preparation method of the stripping fluid is the same as in Example 1, and all steps are identical.

[0062] Comparative Example 4

[0063] The composition of the stripping fluid is as described in Example 1;

[0064] The preparation method of the stripping fluid is the same as in Example 1, except that steps S1 and S2 are adjusted.

[0065] S1. Take 1 / 2 of the mass of propylene glycol monobutyl ether and place it in a container at room temperature. Add methyl salicylate and mix well to obtain solution A.

[0066] S2. Place the remaining propylene glycol monobutyl ether in a container at room temperature, add isopropyl N-phenylthiocarbamate, stir at 400 r / min until completely dissolved, add solution A dropwise at a rate of 2 drops / s, mix well to form a mixture, and obtain solution B.

[0067] Comparative Example 5

[0068] The composition of the stripping fluid is as described in Example 1;

[0069] The preparation method of the stripping fluid is the same as in Example 1, except that step S1 is adjusted and step S2 is omitted. The rest are the same. Specifically:

[0070] S1. Place propylene glycol monobutyl ether in a container, heat to 45°C, add methyl salicylate and isopropyl N-phenyl thiocarbamate, mix well to obtain solution B.

[0071] S2. Add monoethanolamine to solution B and stir until the system is completely homogeneous to obtain solution C;

[0072] S3. The homogeneity of the sample solution C system is tested (no stratification, no precipitation). If it passes the test, it is filtered with an accuracy of 0.22μm to obtain the stripping solution.

[0073] Detection

[0074] 1. Stripping time:

[0075] 100g of the photoresist stripping solutions prepared in Examples 1-3 and Comparative Examples 1-5 were placed in a water bath. The prepared solutions were heated to 70°C. Test wafers (with silicon wafers as substrates and copper bumps) were immersed in the heated photoresist stripping solution at 70°C, and timing was started. After the photoresist on the copper wafer surface was completely removed, the samples were removed and the stripping time was recorded. After being removed with tweezers, the samples were thoroughly rinsed with pure water and dried with nitrogen. The corrosion of the samples was observed under a metallographic optical microscope (OM). The test results are as follows: Figure 1-8 And as shown in Table 1;

[0076] Table 1

[0077]

[0078] As shown in the table above, the photoresist stripping solutions prepared in Examples 1-3 have a good effect on stripping photoresist from copper sheets, and... Figure 1 , 2 It can be clearly seen from Table 3 that after the photoresist was stripped, there were no obvious traces of corrosion on the copper sheet itself, that is, the corrosion inhibitor played an effective protective role. Furthermore, it can also be seen from Table 1 that the photoresist stripping speed of Example 1 is more outstanding, that is, the stripping solution composition and stripping solution preparation method used in Example 1 are more effective.

[0079] Observe the comparative examples in Table 1. Comparative example 5 also showed a relatively fast peeling speed, but... Figure 8It can be seen that while stripping the photoresist, the stripping of the copper sheet is also severe. This indicates that when the stripping solution has the same composition as that in Example 1, the direct mixing of methyl salicylate and isopropyl N-phenylthiocarbamate in a heated environment can easily damage the slow-release effect of the product, resulting in functional loss. In contrast, Comparative Example 2 does not show a significant etching effect on the copper sheet, but its stripping speed is significantly lower than that of Example 1. According to the principle of single comparison, the comparison between Comparative Example 2 and Example 1 is based on the mixed addition of methyl salicylate and isopropyl N-phenylthiocarbamate. That is, the mixed addition of methyl salicylate and isopropyl N-phenylthiocarbamate can achieve the purpose of high stripping efficiency and low corrosion rate of photoresist.

[0080] 2. Corrosion rate

[0081] The following tests were conducted using Ag, Sn, Pb, and Al metal sheets of the same specifications as test pieces.

[0082] The thickness of the test piece is measured as a reference initial thickness value;

[0083] 1. The prepared stripping solution (prepared in Examples 1-3 and Comparative Examples 1-5) was preheated to 70°C in a water bath. Photoresist was coated on the test pieces, and the test pieces were immersed in the prepared and heated solution at 70°C for 30 minutes. After being removed with tweezers, the test pieces were thoroughly rinsed with pure water and dried with nitrogen. The thickness was measured, and the etching rate was calculated as the ratio of the thickness difference before and after immersion to the time (the thickness was measured before and after immersion using a four-point probe machine; the thickness unit is Å, and the etching rate unit is Å / min). The test results are shown in Table 2.

[0084] Table 2

[0085]

[0086] As can be seen from the corrosion rate data obtained from Examples 1-3 in the table above, the corrosion rates of metals Ag, Sn, Pb and Al are all lower than the industry standard (≤2Å / min), and the corrosion rate of metal Ag is the lowest, with a significant corrosion inhibition effect.

[0087] Among Comparative Examples 1-5, Comparative Example 2 showed relatively better results, but its inhibitory effect on Pb metal was not significant. Although it was within industry standards, its effect was still unsatisfactory considering the photoresist stripping speed on copper. In other words, referring to Tables 1 and 2, selecting methyl salicylate as the corrosion inhibitor alone, while satisfying the corrosion inhibition effect for most metals, negatively impacted the photoresist stripping speed. Furthermore, observing the differences in experimental data between Comparative Example 3 and Example 1, and referring to the experimental data in Table 1, it can be seen that maintaining the ratio of N-phenylthiocarbamate to methyl salicylate at ≥2 can produce a better metal corrosion inhibition effect and positively affect the photoresist stripping speed.

[0088] 2. To further verify the corrosion inhibition performance of the above formula on the metal layer, a destructive test was conducted by adding 1% water to the formula, and the thickness was measured again. The etching rate was calculated as the ratio of the thickness difference before and after immersion to time (the thickness was measured before and after immersion using a four-point probe machine, with the thickness unit being Å and the etching rate unit being Å / min). The test results are shown in Table 3.

[0089] Table 3

[0090]

[0091] As shown in the table above, although the corrosion rates of Examples 1-3 were all increased in the water breaking experiment, they were all controlled within a small fluctuation range and were all lower than the corrosion rates of Comparative Examples 1-5, which means that the prepared stripping solution can effectively resist moisture interference.

[0092] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a semiconductor photoresist stripping solution, characterized in that, The stripping fluid, by weight percentage, consists of the following components: 30%-40% organic amines, 1%-3% corrosion inhibitors, and the balance being a polar organic solvent. The corrosion inhibitor is obtained by mixing isopropyl N-phenylthiocarbamate and methyl salicylate. The mass ratio of isopropyl N-phenylthiocarbamate to methyl salicylate is ≥2; The specific preparation steps of the photoresist stripping solution are as follows: S1. Take 1 / 2 of the mass of a polar organic solvent and place it in a container. Heat it to 40-50℃, add methyl salicylate, mix well, and obtain solution A. S2. Place the remaining polar organic solvent in a container at room temperature, add isopropyl N-phenylthiocarbamate, stir until completely dissolved, add solution A dropwise, mix well to form a mixture, adjust the temperature of the mixture to room temperature, and obtain solution B. S3. Add organic amine to solution B and stir until the system is completely homogeneous to obtain solution C; S4. Take a sample solution C to test the homogeneity of the system. If it passes the test, filter it to obtain the stripping solution.

2. The method for preparing the semiconductor photoresist stripping solution according to claim 1, characterized in that, The organic amine is one or more of monoethanolamine, ethylamine, n-propylamine, n-butylamine, diethylamine, and di-n-propylamine.

3. The method for preparing the semiconductor photoresist stripping solution according to claim 1, characterized in that, The polar organic solvent is one or more of diethylene glycol monobutyl ether, propylene glycol monobutyl ether, diethylene glycol monomethyl ether, and propylene glycol monomethyl ether.

4. The method for preparing the semiconductor photoresist stripping solution according to claim 1, characterized in that, The stirring speed in steps S2 and S3 is 300-500 r / min.

5. The method for preparing the semiconductor photoresist stripping solution according to claim 1, characterized in that, The dropping rate in step S2 is 2-3 drops / s.

6. The method for preparing the semiconductor photoresist stripping solution according to claim 1, characterized in that, The filtration accuracy in step S4 is 0.22 μm.

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