Copper chemical mechanical polishing solution for tsv and method for regulating same

Abstract

This invention provides a copper chemical mechanical polishing slurry for TSV wafers and its control method. The polishing slurry, based on a total mass percentage of 100 wt%, comprises 0.5-10 wt% abrasive, 0.1-5 wt% oxidant, 0.01-2 wt% glycine, 0.01-2 wt% alkoxylated fatty alcohol, 0.005-0.5 wt% benzotriazole, 0.005-0.5 wt% mercaptobenzimidazole, 0.01-0.5 wt% bactericide, a pH adjuster, and the balance being deionized water, with a pH value of 4.0-7.0. The control method involves determining the target Cu / TEOS selectivity range and the target copper depression range, adjusting the mass ratio of benzotriazole and mercaptobenzimidazole within their respective content ranges, and then using the adjusted polishing slurry to perform chemical mechanical polishing on the copper layer of the TSV wafer surface. This invention utilizes the synergistic complexation of copper ions by glycine and alkoxylated fatty alcohols, and the formation of a composite passivation layer by benzotriazole and mercaptobenzimidazole, which is beneficial for improving the copper removal rate, adjusting the Cu / TEOS selectivity ratio, and reducing copper pitting.

Description

Technical Field

[0001] This invention relates to the field of chemical mechanical polishing materials, and in particular to a copper chemical mechanical polishing slurry for TSV and its control method. Background Technology

[0002] With the development of 3D integrated packaging and high-performance chip manufacturing technologies, through-silicon via (TSV) technology is widely used to realize vertical electrical interconnects between chips or wafers. TSV structures typically require the formation of vias in a silicon substrate, followed by the sequential deposition of an insulating layer, a barrier layer, a copper seed layer, and an electroplated copper layer. The copper overload layer on the wafer surface is then removed by chemical mechanical polishing, resulting in a flat surface between the copper via surface and the surrounding dielectric or barrier layer.

[0003] Compared to conventional copper interconnect polishing, TSV copper chemical mechanical polishing typically faces thicker copper overload layers and more complex pattern morphologies. On the one hand, the polishing slurry needs to have a high copper removal rate to meet mass production efficiency requirements; on the other hand, the polishing process also needs to control chemical corrosion and local over-polishing of the copper surface to avoid the formation of obvious copper depressions in the copper via areas. If the copper depressions are too large, they can easily affect the reliability of subsequent interconnects or bonding; if the removal rate of dielectric layers such as TEOS is too high, it may lead to dielectric layer damage and erosion of patterned areas.

[0004] Existing copper chemical mechanical polishing slurries often employ amino acid-based complexing agents to promote copper ion complexation, combined with azole corrosion inhibitors such as benzotriazole and aminotriazole to protect the copper surface. While this can improve the copper removal rate and reduce corrosion to some extent, it is still difficult to simultaneously achieve a high copper removal rate, a high Cu / TEOS selectivity ratio, and low copper depression in TSV copper polishing scenarios. When the complexation ability is strong, the risk of static corrosion on the copper surface increases; when the corrosion inhibition is too strong, it may inhibit the removal of copper layers in raised areas, leading to a decrease in polishing efficiency.

[0005] In addition, some organic amine components are highly alkaline, posing a compatibility risk to low-k or ultra-low-k dielectric materials. Therefore, a copper chemical mechanical polishing slurry for TSV and its control method are proposed. Summary of the Invention

[0006] In view of this, the present invention provides a copper chemical mechanical polishing slurry for TSV and a method for controlling the slurry thereof, so as to solve or alleviate the technical problems existing in the prior art, and at least provide a beneficial alternative.

[0007] The technical solution of the present invention is implemented as follows: a copper chemical mechanical polishing slurry for TSV, comprising the following components based on a total mass percentage of 100 wt% of the polishing slurry: Abrasive 0.5-10wt%, oxidant 0.1-5wt%, first complexing agent 0.01-2wt%, second complexing agent 0.01-2wt%, first corrosion inhibitor 0.005-0.5wt%, second corrosion inhibitor 0.005-0.5wt%, bactericide 0.01-0.5wt%, pH adjuster, and balance deionized water; Wherein, the first complexing agent is glycine, the second complexing agent is alkoxylated fatty alcohol, the first corrosion inhibitor is benzotriazole, the second corrosion inhibitor is mercaptobenzimidazole, and the pH value of the polishing solution is 4.0-7.0.

[0008] Furthermore, the abrasive is colloidal silica abrasive particles with a particle size of 50-120 nm.

[0009] Furthermore, the oxidant is hydrogen peroxide.

[0010] Furthermore, the second complexing agent is a C-type compound having ethoxy and butoxy units. 12 Alkoxylated fatty alcohols.

[0011] Furthermore, the second complexing agent is (ethoxy)8(butoxy) 10 C 12 alcohol.

[0012] Furthermore, the bactericide is an isothiazolinone compound.

[0013] Furthermore, the pH adjuster includes nitric acid and potassium hydroxide, and the pH value of the polishing solution is 5.5-6.5.

[0014] Furthermore, the mass ratio of the first corrosion inhibitor to the second corrosion inhibitor is adjusted according to the Cu / TEOS selectivity requirement.

[0015] The present invention also provides a method for controlling the copper chemical mechanical polishing slurry for TSV, comprising the following steps: Step 1: Determine the target Cu / TEOS selectivity ratio range and the target copper recess range during the TSV copper chemical mechanical polishing process; Step 2: Prepare a copper chemical mechanical polishing slurry for TSV. The copper chemical mechanical polishing slurry for TSV, based on a total mass percentage of 100wt%, includes 0.5-10wt% abrasive, 0.1-5wt% oxidant, 0.01-2wt% glycine, 0.01-2wt% alkoxylated fatty alcohol, 0.005-0.5wt% benzotriazole, 0.005-0.5wt% mercaptobenzimidazole, 0.01-0.5wt% bactericide, pH adjuster, and the balance being deionized water. It does not contain ethylenediamine, and the pH value of the copper chemical mechanical polishing slurry for TSV is 4.0-7.0. Step 3: When the mass percentage content of benzotriazole and mercaptobenzimidazole is maintained in the range of 0.005-0.5wt%, adjust the mass percentage content ratio of benzotriazole to mercaptobenzimidazole according to the target Cu / TEOS selection ratio range and the target copper depression range. Step 4: Perform chemical mechanical polishing on the copper layer on the surface of the TSV wafer using the adjusted copper chemical mechanical polishing slurry for TSV, so that the polished Cu / TEOS selectivity ratio falls into the target Cu / TEOS selectivity ratio range, and the polished copper depression falls into the target copper depression range.

[0016] Furthermore, during chemical mechanical polishing, the working pressure is 2.0-4.0 psi, the polishing disc speed is 80-100 rpm, the wafer speed is 85-95 rpm, the polishing fluid flow rate is 200-400 mL / min, and the polishing time is 60 s. When the target Cu / TEOS selectivity is greater than the Cu / TEOS selectivity corresponding to the current copper chemical mechanical polishing slurry used for TSV, or the target copper depression value is less than the copper depression value corresponding to the current copper chemical mechanical polishing slurry used for TSV, increase the mass ratio of mercaptobenzimidazole to benzotriazole. When the target copper removal rate is greater than the copper removal rate corresponding to the copper chemical mechanical polishing slurry currently used for TSV, reduce the mass ratio of mercaptobenzimidazole to benzotriazole.

[0017] The embodiments of the present invention have the following advantages due to the adoption of the above technical solutions: I. This invention uses glycine and alkoxylated fatty alcohol to form a dual complexing agent system. Glycine can promote the complexation of copper ions, while alkoxylated fatty alcohol can improve the wetting state of the polishing interface and assist the migration of reaction products on the copper surface. The combination of the two is beneficial to improve the TSV copper layer removal rate, while reducing the risk of excessive corrosion of the copper surface under a single complexing agent system.

[0018] II. This invention employs a dual corrosion inhibitor system consisting of benzotriazole and mercaptobenzimidazole. Benzotriazole can form an adsorption protective layer on the copper surface, while mercaptobenzimidazole can enhance the binding ability to the copper surface. When the two work together, they can form a relatively stable composite passivation layer, which allows the polishing slurry to maintain its copper removal capacity while inhibiting the continued dissolution of copper in areas with low mechanical action, thereby helping to reduce copper depressions and improve the surface morphology after polishing.

[0019] Third, by adjusting the mass percentage ratio of benzotriazole to mercaptobenzimidazole, this invention changes the degree of formation of the composite passivation layer on the copper surface, so that the Cu / TEOS selectivity ratio and copper depression can be adjusted according to the initial copper layer thickness, pattern density and planarization requirements of different TSV wafers, thereby improving the adaptability of the polishing slurry to different TSV process windows.

[0020] Fourth, the polishing solution used in the control method of the present invention does not contain ethylenediamine and controls the pH within the range of 4.0-7.0, which helps to reduce the risk of alkaline organic amines affecting low-k or ultra-low-k media materials; at the same time, the addition of bactericide to the polishing solution helps to improve the stability of the polishing solution during storage and use. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a flowchart of the steps for controlling the copper chemical mechanical polishing slurry used in TSV according to the present invention. Detailed Implementation

[0023] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0024] This invention provides a copper chemical mechanical polishing slurry for TSV (Total Vapor Enhancement). Based on a total mass percentage of 100 wt%, the slurry comprises 0.5-10 wt% abrasive, 0.1-5 wt% oxidant, 0.01-2 wt% first complexing agent, 0.01-2 wt% second complexing agent, 0.005-0.5 wt% first corrosion inhibitor, 0.005-0.5 wt% second corrosion inhibitor, 0.01-0.5 wt% bactericide, pH adjuster, and the balance deionized water. The first complexing agent is glycine, the second complexing agent is alkoxylated fatty alcohol, the first corrosion inhibitor is benzotriazole, the second corrosion inhibitor is mercaptobenzimidazole, and the pH of the slurry is 4.0-7.0.

[0025] In one embodiment, the abrasive is colloidal silica abrasive particles with a particle size of 50-120 nm; the oxidant is hydrogen peroxide; and the second complexing agent is C44 having ethoxy and butoxy units. 12 Alkoxylated fatty alcohols, further converted to (ethoxy)-8-(butoxy)- 10 C 12 Alcohol; bactericide is isothiazolinone compound; pH adjuster includes nitric acid and potassium hydroxide, and the pH value of the polishing solution is preferably 5.5-6.5.

[0026] Glycine can form complexes with copper ions, promoting the migration of copper oxidation products from the copper surface; alkoxylated fatty alcohols can improve the wetting state of the polishing interface and assist in the transfer of reaction products on the copper surface. Benzotriazole can form an adsorption protective layer on the copper surface, while mercaptobenzimidazole can enhance its binding ability to the copper surface. When benzotriazole and mercaptobenzimidazole are used in combination, a composite passivation layer can be formed on the copper surface, inhibiting the continued dissolution of copper in low-mechanical-action areas and destroying the passivation layer in protruding areas under the shearing action of abrasives, thus achieving a balance between copper removal, Cu / TEOS selectivity, and copper depression control.

[0027] like Figure 1 As shown, the present invention also provides a method for preparing a polishing slurry: When preparing the copper chemical mechanical polishing slurry for TSV, deionized water is added to the preparation container, and abrasive is added while stirring to ensure uniform dispersion of the abrasive in the deionized water. Then, glycine and alkoxylated fatty alcohol are added, and stirring continues to ensure uniform dispersion of glycine and alkoxylated fatty alcohol. Next, benzotriazole, mercaptobenzimidazole, and bactericide are added, and stirring continues. Finally, hydrogen peroxide is added, and the pH of the system is adjusted to 4.0-7.0 using a pH adjuster to obtain the copper chemical mechanical polishing slurry for TSV.

[0028] When it is necessary to adjust the Cu / TEOS selectivity ratio and copper depression, the mass percentage content of benzotriazole and mercaptobenzimidazole should be maintained within the range of 0.005-0.5wt%. The mass percentage content ratio of benzotriazole to mercaptobenzimidazole should be adjusted according to the target Cu / TEOS selectivity ratio range and the target copper depression range.

[0029] Performance testing methods: The CMP test conditions used in the following examples and comparative examples are: working pressure 2.0-4.0 psi, polishing disc speed 80-100 rpm, wafer speed 85-95 rpm, polishing fluid flow rate 200-400 mL / min, and polishing time 60 s. For specific evaluation, the test conditions are: working pressure 3.0 psi, polishing disc speed 90 rpm, wafer speed 90 rpm, polishing fluid flow rate 300 mL / min, and polishing time 60 s.

[0030] The copper removal rate is calculated by dividing the difference in copper film thickness before and after polishing by the polishing time. Specifically, a test wafer with a copper film formed on its surface is selected, and the initial thickness of the copper film is measured before polishing. After polishing is completed according to the set CMP conditions, the remaining thickness of the copper film is measured again. The difference between the initial thickness and the remaining thickness of the copper film is taken as the copper film removal thickness, and the copper removal rate is calculated according to "copper removal rate = copper film removal thickness / polishing time".

[0031] The TEOS removal rate was determined using the same method. Test wafers with a TEOS dielectric layer on their surface were selected and polished under the same CMP conditions. The change in TEOS dielectric layer thickness before and after polishing was measured. The TEOS removal rate was obtained by dividing the removed TEOS dielectric layer thickness by the polishing time. The Cu / TEOS selectivity ratio was calculated as the ratio of the copper removal rate to the TEOS removal rate.

[0032] The static corrosion rate was determined using the static immersion method. The copper film test piece was immersed in the corresponding polishing solution and left to stand for a predetermined time at the same or similar temperature as the polishing solution. After removal, it was rinsed with deionized water and dried. The change in copper film thickness before and after immersion was measured, and the static corrosion rate was calculated by dividing the change in copper film thickness by the immersion time.

[0033] Surface roughness Ra was measured using an atomic force microscope or a white light interferometer profilometer. Multiple test areas were selected on the polished copper film surface, and the root mean square roughness of each test area was calculated and averaged. Copper depressions were measured using a step profilometer or a white light interferometer profilometer. In the TSV patterned wafer, the copper via area and the adjacent dielectric layer area were selected, and the height difference between the copper surface and the adjacent dielectric layer surface was measured. This height difference was used as the copper depression value.

[0034] Example 1 This embodiment provides a copper chemical mechanical polishing slurry for TSV, used to evaluate the effect of glycine and alkoxylated fatty alcohol combination on copper removal rate, static corrosion rate and surface roughness.

[0035] The copper chemical mechanical polishing slurry for TSV comprises the following components: 3.0 wt% colloidal silica abrasive particles, 1.0 wt% hydrogen peroxide, 0.15 wt% benzotriazole, 0.05 wt% mercaptobenzimidazole, 0.05 wt% isothiazolinone bactericide, and glycine and (ethoxy)-8 (butoxy) in different concentrations. 10 C 12 Alcohol, pH adjuster, and the remainder deionized water; The colloidal silica abrasive particles have a particle size of 80 nm; the pH adjuster is nitric acid and potassium hydroxide, and the pH value of the resulting polishing solution is adjusted to 6.0.

[0036] During preparation, deionized water is added to the preparation container, and colloidal silica abrasive particles are added while stirring. After the colloidal silica abrasive particles are evenly dispersed, glycine and (ethoxy)8(butoxy) 10 C 12 The alcohol was stirred continuously; then benzotriazole, mercaptobenzimidazole and isothiazolinone bactericides were added; the pH was adjusted to 6.0 with nitric acid and potassium hydroxide and then hydrogen peroxide was added to obtain the copper chemical mechanical polishing slurry for TSV in this embodiment.

[0037] The polishing slurry obtained in this embodiment was added to a CMP polishing machine to perform chemical mechanical polishing on the copper film test wafer. The CMP test conditions were: working pressure 3.0 psi, polishing disc speed 90 rpm, wafer speed 90 rpm, polishing slurry flow rate 300 mL / min, and polishing time 60 s.

[0038] Comparative Example 1 This comparative example provides a copper chemical mechanical polishing slurry for TSV containing only glycine as a complexing agent.

[0039] Compared to Example 1, this comparative example does not contain (ethoxy)-8 (butoxy)-. 10 C 12 Alcohol, specifically (ethoxy)-8 (butoxy). 10 C 12 The alcohol content was 0 wt%, and only 0.10 wt% glycine was added; the remaining components, contents, pH value, and CMP test conditions were the same as in Example 1.

[0040] Comparative Example 2 This comparative example provides a copper chemical mechanical polishing slurry for TSV containing only alkoxylated fatty alcohols as complexing components.

[0041] Compared to Example 1, this comparative example does not contain glycine, i.e., the glycine content is 0 wt%, and only (ethoxy)8 (butoxy) is added. 10 C 12Alcohol 0.30 wt%; the remaining components, contents, pH value and CMP test conditions are the same as in Example 1.

[0042] Test Example 1: The Effect of a Dual Complexing Agent System on Copper Polishing Performance The polishing performance of the polishing slurries of Example 1, Comparative Example 1 and Comparative Example 2 was tested according to the above test method. The test results are shown in Table 1.

[0043] Table 1: Effect of dual complexing agent system on copper polishing performance

[0044] Table 1 shows that in Comparative Example 1, when glycine was used alone as a complexing agent, the copper removal rate was 24800 Å / min, the static corrosion rate was 18 Å / min, and the surface roughness Ra was 1.6 nm. These results indicate that glycine can promote copper removal by complexing copper ions, but when used alone, it has a strong chemical corrosion effect on the copper surface and is not conducive to inhibiting the continued dissolution of copper in areas with low mechanical action.

[0045] Comparative Example 2 uses only (ethoxy)-8 (butoxy)-. 10 C 12 In the case of alcohol, the copper removal rate was 15600 Å / min, lower than that of Comparative Example 1 and Example 1. This result indicates that (ethoxy)8(butoxy) 10 C 12 When alcohol is used alone, its ability to complex and migrate copper ions is insufficient, making it difficult to meet the high copper removal rate requirements of TSV copper chemical mechanical polishing.

[0046] In Example 1, glycine and (ethoxy)-8 (butoxy) were used simultaneously. 10 C 12 When alkoxylated fatty alcohols are used, the copper removal rate increases to 38,500 Å / min, the static corrosion rate decreases to 7 Å / min, and the surface roughness Ra decreases to 0.9 nm. These results indicate that when glycine and alkoxylated fatty alcohols are used together, glycine provides copper ion complexation capabilities, while the alkoxylated fatty alcohols improve the wetting state of the polishing interface and assist in the migration of reaction products on the copper surface. This results in increased copper removal rate while reducing static corrosion and improving the surface roughness after polishing.

[0047] Example 2 This embodiment provides a copper chemical mechanical polishing slurry for TSV, used to evaluate the regulatory effect of the combination of benzotriazole and mercaptobenzimidazole on Cu / TEOS selectivity and copper depression.

[0048] The copper chemical mechanical polishing slurry for TSV comprises the following components: 3.0 wt% colloidal silica abrasive particles, 1.0 wt% hydrogen peroxide, 1.0 wt% glycine, and (ethoxy)-8 (butoxy) 10 C 12 The composition includes 0.30 wt% alcohol, 0.05 wt% isothiazolinone bactericide, benzotriazole and mercaptobenzimidazole in different concentrations, pH adjuster, and the remainder deionized water. The colloidal silica abrasive particles have a particle size of 80 nm. The pH adjuster consists of nitric acid and potassium hydroxide, adjusting the pH of the resulting polishing solution to 6.0.

[0049] The preparation method in this embodiment is the same as in Example 1. The polishing slurry obtained in this embodiment is used for CMP testing of TSV patterned wafers and TEOS dielectric layer test wafers. The test conditions are: working pressure 3.0 psi, polishing disk speed 90 rpm, wafer speed 90 rpm, polishing slurry flow rate 300 mL / min, and polishing time 60 s.

[0050] Comparative Example 3 This comparative example provides a copper chemical mechanical polishing slurry for TSV that uses only benzotriazole as a corrosion inhibitor.

[0051] Compared with Example 2, this comparative example does not contain mercaptobenzimidazole, that is, the content of mercaptobenzimidazole is 0 wt%, and only 0.15 wt% benzotriazole is added; the other components, contents, pH value and CMP test conditions are the same as those in Example 2.

[0052] Comparative Example 4 This comparative example provides a copper chemical mechanical polishing slurry for TSV that uses only mercaptobenzimidazole as a corrosion inhibitor.

[0053] Compared with Example 2, this comparative example does not contain benzotriazole, i.e., the content of benzotriazole is 0 wt%, and only 0.05 wt% mercaptobenzimidazole is added; the remaining components, contents, pH value and CMP test conditions are the same as in Example 2.

[0054] Test Example 2: Effect of a dual corrosion inhibitor system on Cu / TEOS selectivity and copper pitting According to the above test method, the polishing slurries of Example 2, Comparative Example 3 and Comparative Example 4 were tested for Cu / TEOS selectivity ratio and copper depression. The test results are shown in Table 2.

[0055] Table 2: Effect of dual corrosion inhibitor system on Cu / TEOS selectivity ratio and copper pitting

[0056] Table 2 shows that in Comparative Example 3, when benzotriazole was used alone, the Cu / TEOS selectivity ratio was 450:1, and the copper depression was 85 nm. This result indicates that although benzotriazole can form an adsorption protective layer on the copper surface, the density of the single benzotriazole protective layer is insufficient under the chemical corrosion and mechanical shearing conditions of TSV copper chemical mechanical polishing, making it difficult to adequately suppress the continuous dissolution of copper in areas with low mechanical interaction.

[0057] In Comparative Example 4, when mercaptobenzimidazole was used alone, the Cu / TEOS selectivity ratio increased to 1290:1, and the copper depression decreased to 52 nm, but the copper removal rate decreased to 28400 Å / min. These results indicate that mercaptobenzimidazole has a strong protective effect on the copper surface, improving the selectivity and reducing copper depression. However, when used alone, its protective effect is too strong, which may inhibit the effective removal of the copper layer in the protruding areas, thereby reducing the copper removal rate.

[0058] In Example 2, when benzotriazole and mercaptobenzimidazole were used simultaneously, the Cu / TEOS selectivity ratio reached 3234:1, and the copper depression was reduced to 32 nm. This result indicates that the combination of benzotriazole and mercaptobenzimidazole can form a composite passivation layer on the copper surface. This composite passivation layer maintains good protection in TSV depression regions or low mechanical action regions to inhibit further copper dissolution; however, in protruding regions or high mechanical action regions, it can be destroyed by abrasive shearing, allowing the copper surface to continue participating in oxidation, complexation, and mechanical removal processes. Therefore, this dual corrosion inhibitor system can improve the Cu / TEOS selectivity ratio and reduce copper depression.

[0059] Example 3 This embodiment provides a method for controlling the copper chemical mechanical polishing slurry for TSV, illustrating the process of controlling the Cu / TEOS selectivity and copper depression by adjusting the mass percentage ratio of benzotriazole to mercaptobenzimidazole.

[0060] Step 1: Determine the target Cu / TEOS selectivity ratio range and the target copper depression range during the TSV copper chemical mechanical polishing process. In this embodiment, the target Cu / TEOS selectivity ratio is set to 3000:1 or higher, and the target copper depression is set to no higher than 35nm.

[0061] Step 2: Prepare the copper chemical mechanical polishing slurry for TSV. The copper chemical mechanical polishing slurry for TSV comprises the following components: 3.0 wt% colloidal silica abrasive particles, 1.0 wt% hydrogen peroxide, 1.0 wt% glycine, and (ethoxy)-8 (butoxy) 10 C 12The composition includes 0.30 wt% alcohol, 0.15 wt% benzotriazole, 0.05 wt% mercaptobenzimidazole, 0.05 wt% isothiazolinone bactericide, pH adjuster, and the balance deionized water, and it does not contain ethylenediamine. The colloidal silica abrasive particles have a particle size of 80 nm, and the pH adjuster consists of nitric acid and potassium hydroxide, adjusting the pH of the resulting polishing solution to 6.0.

[0062] Step 3: Determine the mass percentage ratio of benzotriazole to mercaptobenzimidazole based on the target Cu / TEOS selectivity range and the target copper depression range. In this embodiment, the mass percentage of benzotriazole is 0.15 wt%, and the mass percentage of mercaptobenzimidazole is 0.05 wt%, both falling within the range of 0.005-0.5 wt%. Compared to using only benzotriazole or only mercaptobenzimidazole, the combination of benzotriazole and mercaptobenzimidazole enhances the formation of the composite passivation layer on the copper surface, thereby increasing the Cu / TEOS selectivity ratio and reducing copper depression.

[0063] Step 4: The copper layer on the TSV wafer surface is chemically and mechanically polished using the copper chemical mechanical polishing slurry for TSV prepared in Step 3. During polishing, the working pressure is 3.0 psi, the polishing disc speed is 90 rpm, the wafer speed is 90 rpm, the slurry flow rate is 300 mL / min, and the polishing time is 60 s. Testing showed that after polishing with the copper chemical mechanical polishing slurry for TSV in this embodiment, the Cu / TEOS selectivity ratio is 3234:1, and the copper depression is 32 nm, meeting the target Cu / TEOS selectivity ratio range and the target copper depression range.

[0064] As can be seen from Examples 1 to 3 and Comparative Examples 1 to 4, the present invention improves the copper removal rate and reduces static corrosion through a dual complexing agent system composed of glycine and alkoxylated fatty alcohol; improves the Cu / TEOS selectivity and reduces copper pitting through a dual corrosion inhibitor system composed of benzotriazole and mercaptobenzimidazole; and regulates the Cu / TEOS selectivity and copper pitting during the TSV copper chemical mechanical polishing process by adjusting the mass percentage ratio of benzotriazole and mercaptobenzimidazole.

[0065] Other implementation methods While maintaining the basic functional relationship of the polishing slurry for TSV copper chemical mechanical polishing, some components in the above embodiments can be replaced or combined according to the copper layer thickness, dielectric layer type and planarization requirements.

[0066] In one embodiment, the abrasive is preferably colloidal silica abrasive particles; in other embodiments, the abrasive may also be selected from one or more of fumed silica, alumina, cerium oxide, titanium dioxide, zirconium oxide, and polymer microspheres. The particle size of the abrasive can be adjusted according to the copper layer thickness, target surface roughness, and polishing efficiency requirements, for example, it can be 20-200 nm.

[0067] In one embodiment, the oxidant is preferably hydrogen peroxide; in other embodiments, the oxidant may also be selected from one or more of urea peroxide, peracetic acid, potassium periodate, potassium iodate, ferric nitrate, and nitric acid. The oxidant is used to oxidize the copper surface to form copper oxide products on the copper surface that can be complexed by a complexing agent and removed by mechanical action.

[0068] In one embodiment, the second complexing agent is preferably (ethoxy)8(butoxy) 10 C 12 Alcohol; in other embodiments, the second complexing agent may also be a nonionic surfactant with an amphiphilic structure, including one or more of fatty alcohol polyoxyethylene ethers, alkylphenol polyoxyethylene ethers, polyethylene glycol, polypropylene glycol, and ethylene oxide-propylene oxide block copolymers. The second complexing agent is used to coordinate with glycine to improve the wetting state of the polishing interface and assist the migration of reaction products on the copper surface.

[0069] In one embodiment, the first corrosion inhibitor is preferably benzotriazole; in other embodiments, the first corrosion inhibitor may also be selected from one or more of methylbenzotriazole, 5-aminotetrazole, 1,2,4-triazole, 3-amino-1,2,4-triazole, 5-methyl-1H-benzotriazole, imidazole, and 2-methylimidazole. The first corrosion inhibitor is used to form an adsorption protective layer on the copper surface.

[0070] In one embodiment, the second corrosion inhibitor is preferably mercaptobenzimidazole; in other embodiments, the second corrosion inhibitor may also be selected from one or more of 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, mercaptoacetic acid, thiourea, and sodium diethyldithiocarbamate. The second corrosion inhibitor is used to enhance the adhesion to the copper surface and, in conjunction with the first corrosion inhibitor, forms a composite passivation layer.

[0071] In one embodiment, the pH adjuster preferably includes nitric acid and potassium hydroxide; in other embodiments, the pH adjuster may also be selected from one or more of sulfuric acid, phosphoric acid, acetic acid, and sodium hydroxide. Other acidic or alkaline pH adjusters may also be used to adjust the pH of the system without causing the polishing solution pH to exceed 4.0-7.0 and without affecting the compatibility of the media materials.

[0072] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various variations or substitutions within the technical scope disclosed in the present invention, and these should all be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A copper chemical mechanical polishing slurry for TSV, characterized in that, The polishing slurry comprises the following components, based on a total mass percentage of 100 wt%: Abrasive 0.5-10wt%, oxidant 0.1-5wt%, first complexing agent 0.01-2wt%, second complexing agent 0.01-2wt%, first corrosion inhibitor 0.005-0.5wt%, second corrosion inhibitor 0.005-0.5wt%, bactericide 0.01-0.5wt%, pH adjuster, and balance deionized water; Wherein, the first complexing agent is glycine, the second complexing agent is alkoxylated fatty alcohol, the first corrosion inhibitor is benzotriazole, the second corrosion inhibitor is mercaptobenzimidazole, and the pH value of the polishing solution is 4.0-7.

0.

2. The copper chemical mechanical polishing slurry for TSV according to claim 1, characterized in that, The abrasive is colloidal silica abrasive particles with a particle size of 50-120 nm.

3. The copper chemical mechanical polishing slurry for TSV according to claim 1, characterized in that, The oxidant is hydrogen peroxide.

4. The copper chemical mechanical polishing slurry for TSV according to claim 1, characterized in that, The second complexing agent is a C-type compound having ethoxy and butoxy units. 12 Alkoxylated fatty alcohols.

5. The copper chemical mechanical polishing slurry for TSV according to claim 4, characterized in that, The second complexing agent is (ethoxy)-8(butoxy). 10 C 12 alcohol.

6. The copper chemical mechanical polishing slurry for TSV according to claim 1, characterized in that, The bactericide is an isothiazolinone compound.

7. The copper chemical mechanical polishing slurry for TSV according to claim 1, characterized in that, The pH adjuster includes nitric acid and potassium hydroxide, and the pH value of the polishing solution is 5.5-6.

5.

8. The copper chemical mechanical polishing slurry for TSV according to claim 1, characterized in that, The mass ratio of the first corrosion inhibitor to the second corrosion inhibitor is adjusted according to the Cu / TEOS selectivity ratio requirement.

9. A method for controlling the copper chemical mechanical polishing slurry for TSV, characterized in that, Includes the following steps: Step 1: Determine the target Cu / TEOS selectivity ratio range and the target copper recess range during the TSV copper chemical mechanical polishing process; Step 2: Prepare a copper chemical mechanical polishing slurry for TSV. The copper chemical mechanical polishing slurry for TSV, based on a total mass percentage of 100wt%, includes 0.5-10wt% abrasive, 0.1-5wt% oxidant, 0.01-2wt% glycine, 0.01-2wt% alkoxylated fatty alcohol, 0.005-0.5wt% benzotriazole, 0.005-0.5wt% mercaptobenzimidazole, 0.01-0.5wt% bactericide, pH adjuster, and the balance being deionized water. It does not contain ethylenediamine, and the pH value of the copper chemical mechanical polishing slurry for TSV is 4.0-7.

0. Step 3: When the mass percentage content of benzotriazole and mercaptobenzimidazole is maintained in the range of 0.005-0.5wt%, adjust the mass percentage content ratio of benzotriazole to mercaptobenzimidazole according to the target Cu / TEOS selection ratio range and the target copper depression range. Step 4: Perform chemical mechanical polishing on the copper layer on the surface of the TSV wafer using the adjusted copper chemical mechanical polishing slurry for TSV, so that the polished Cu / TEOS selectivity ratio falls into the target Cu / TEOS selectivity ratio range, and the polished copper depression falls into the target copper depression range.

10. The method for controlling the copper chemical mechanical polishing slurry for TSV according to claim 9, characterized in that, When performing chemical mechanical polishing, the working pressure is 2.0-4.0 psi, the polishing disc speed is 80-100 rpm, the wafer speed is 85-95 rpm, the polishing fluid flow rate is 200-400 mL / min, and the polishing time is 60 s. When the target Cu / TEOS selectivity is greater than the Cu / TEOS selectivity corresponding to the current copper chemical mechanical polishing slurry used for TSV, or the target copper depression value is less than the copper depression value corresponding to the current copper chemical mechanical polishing slurry used for TSV, increase the mass ratio of mercaptobenzimidazole to benzotriazole. When the target copper removal rate is greater than the copper removal rate corresponding to the copper chemical mechanical polishing slurry currently used for TSV, reduce the mass ratio of mercaptobenzimidazole to benzotriazole.

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