Cleaning composition for silicon carbide wafer

Abstract

A composition for cleaning SiC wafers polished by an abrasive containing manganese dioxide is provided, said composition Organic acids with a pKa of less than 3; and Includes inorganic acid; and The above inorganic acid is selected from the group consisting of sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, and combinations thereof.

Description

Technology Field

[0001] The present disclosure relates to a composition used to clean a SiC wafer polished after using an abrasive containing manganese dioxide (MnO2). Background Technology

[0003] SiC is a crystalline semiconductor material recognized for its advantages in terms of wide band gap characteristics, as well as extreme hardness, high thermal conductivity, and chemical inertness. These characteristics make SiC a highly attractive semiconductor for the manufacture of power semiconductor devices, enabling improved power density and performance compared to devices made from more common materials such as silicon. In particular, SiC wafers possess a higher dielectric breakdown field strength than conventional Si wafers used in power semiconductors. This high dielectric breakdown field strength of SiC makes SiC wafers advantageous for use in automotive batteries.

[0004] Meanwhile, semiconductor wafers are manufactured by forming a deposition layer of a metal film serving as wiring or an interlayer insulating film on a silicon substrate, then planarizing the surface using a chemical mechanical polishing (hereinafter abbreviated as "CMP") process that uses an abrasive consisting of a water-based slurry containing abrasive particles, and stacking a new layer on the planarized surface. Since the microfabrication of semiconductor wafers requires high-precision planarity in each layer, the importance of planarization treatment by CMP is very high.

[0005] In addition, the semiconductor wafer requires a chemical mechanical polishing process even before being connected to metal wiring, and the types of abrasives used in each polishing process differ. That is, the abrasive used on the wafer after metal wiring is connected is different from the abrasive used to polish the wafer alone before wiring is connected. Examples of materials used for metal wiring include copper, tungsten, and aluminum, while the abrasive used on wafers with connected metal wiring is used to build up the semiconductor's fine patterns and primarily contains silica, aluminum particles, etc.

[0006] Generally known known technologies include compositions related to post-CMP cleaning agents for removing abrasive components remaining on the wafer surface after planarization via a CMP process following copper wiring for semiconductors. Generally, cleaning agent compositions based on basic compositions or compositions containing organic acids and anti-corrosion agents to prevent copper corrosion are known (see Korean Published Document No. 10-2018-0122138, Korean Published Document No. 10-2011-0036184, etc.).

[0007] On the other hand, an abrasive containing MnO2 can be used in the CMP process to improve the flatness of SiC wafers without connected metal wiring.

[0008] Abrasives primarily contain metal oxides such as CeO2, SiO2, and MnO2. Since these metal oxides remain on the wafer after the polishing process is completed, a cleaning process is required to remove them. However, because the abrasives used vary depending on the type of wafer, the cleaning agents required to remove the residual abrasives after polishing also differ for each wafer. In particular, the types of metal oxides contained in each abrasive differ; consequently, there is a problem in that residual MnO2 is not completely removed after using MnO2-containing abrasives because none of the existing cleaning agents possess high cleaning power against MnO2. Furthermore, in addition to the abrasive components, various foreign substances such as particles and metals are generated during the polishing process, and cleaning of these contaminants is also necessary.

[0009] In addition, some conventional cleaning agents contain ascorbic acid, but ascorbic acid has a short half-life, so cleaning agent solutions containing it are unstable and have the problem of leaving residue on the wafer after cleaning (Korean Published Patent Document No. 10-2014-0106528).

[0010] Therefore, there is a need for a cleaning agent capable of removing all residual MnO2 components and other foreign substances after the use of MnO2-containing abrasives. Prior art literature

[0012] Korean Published Patent Document No. 10-2018-0122138 (2018.11.12) Korean Published Patent Document No. 10-2011-0036184 (2011.04.31) Korean Published Patent Document No. 10-2014-0106528 (2014.09.03) The problem to be solved

[0013] The present disclosure provides a cleaning composition for cleaning a SiC wafer polished by an abrasive containing manganese dioxide. means of solving the problem

[0015] To achieve the above-mentioned purpose, the present disclosure relates to a composition for cleaning a SiC wafer polished by an abrasive containing manganese dioxide, wherein the composition is

[0016] pK a Organic acids with a value of less than 3; and

[0017] Includes inorganic acid; and

[0018] The present invention provides a composition for cleaning SiC wafers, wherein the inorganic acid is selected from the group consisting of sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, and combinations thereof. Effects of the invention

[0020] When a SiC wafer polished by an abrasive containing manganese dioxide is cleaned using a SiC wafer cleaning composition according to the present disclosure, manganese dioxide remaining on the substrate after cleaning can be removed. In addition, the SiC wafer cleaning composition also has excellent cleaning power against particulate matter and metallic materials generated during the polishing process, such as calcium, iron, nickel, zinc, sulfur, etc.

[0021] Accordingly, by cleaning a SiC wafer polished by an abrasive containing manganese dioxide using a SiC wafer cleaning composition according to the present disclosure, a clean SiC wafer can be provided. Specific details for implementing the invention

[0023] A composition for cleaning SiC wafers polished by an abrasive containing manganese dioxide according to the present disclosure

[0024] pK a Organic acids with a value of less than 3; and

[0025] Includes inorganic acid; and

[0026] The above inorganic acid is selected from the group consisting of sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, and combinations thereof.

[0028] According to one embodiment, the organic acid is pK aIt includes a carboxyl group of less than 3. The organic acid is selected from the group consisting of dichloroacetic acid, oxalic acid, maleic acid, malonic acid, glutamic acid, arginine, glycine, pyruvic acid, tartaric acid, and combinations thereof.

[0029] Conventional cleaning agents typically contain organic acids that act as oxidizing agents. However, the cleaning composition according to the present disclosure does not contain an oxidizing agent. Rather, the cleaning composition according to the present disclosure contains an organic acid that acts as a reducing agent. Such organic acid acting as a reducing agent is Mn in manganese dioxide 4+ Mn ions 2+ It plays the role of reducing to ions.

[0030] The cleaning agent composition according to the present disclosure has the advantage of being able to remove manganese dioxide without generating residue.

[0032] According to one embodiment, the inorganic acid acts as a pH adjuster. The pH of the cleaning composition according to the present disclosure is acidic and is less than 3, preferably less than 2, and more preferably less than 1.5. The pH adjustment by the inorganic acid in the composition serves to change the pH of the composition to a pH range in which the organic acid can reduce manganese dioxide. In the region where the pH is 7 or higher, the reduction rate of manganese dioxide can be slowed down even when using an excellent reducing agent.

[0034] According to one embodiment, the cleaning composition according to the present disclosure further comprises a solvent. The solvent is not an organic solvent and preferably comprises water.

[0035] According to one embodiment, the cleaning composition according to the present disclosure further comprises an inorganic salt. In the above embodiment, the inorganic salt is selected from the group consisting of sodium sulfate, potassium sulfate, magnesium sulfate, ammonium sulfate, aluminum sulfate, sodium nitrate, potassium nitrate, ammonium nitrate, calcium nitrate, sodium chloride, magnesium chloride, calcium chloride, potassium chloride, ammonium chloride, sodium bromide, potassium bromide, sodium iodide, potassium iodide, and combinations thereof. The inorganic salt acts as an ion stabilizer. As previously described, since organic acids act as reducing agents, Mn 2+ Ions are formed, and inorganic salts are such Mn 2+ It can act to stabilize ions.

[0036] Manganese ions reduced by organic acids in an aqueous solution can react with anions of inorganic salts to form bonds, and these bonded manganese ions can help stabilize equilibrium in the aqueous solution while inhibiting oxidation to manganese dioxide, and can be more effective in cleaning.

[0038] According to one embodiment, the organic acid is included in an amount of about 0.1% by weight and about 50% by weight or less based on the weight of the total composition. In one embodiment, the inorganic acid is included in an amount of about 0.1% by weight and about 10% by weight or less based on the weight of the total composition. The remaining weight percentage constituting the composition is the weight percentage of water as a solvent. Specifically, water is included in an amount of about 20% by weight to about 97.3% by weight based on the weight of the total composition.

[0039] The above inorganic salt may be additionally included in an amount of about 0.1% by weight or more and about 10% by weight or less based on the weight of the total composition.

[0041] A cleaning composition according to the present disclosure is described more specifically below, and the present disclosure is not limited to the scope of the specific description below.

[0043] Preparation Example: Preparation of a composition for cleaning SiC wafers

[0045] A composition for cleaning SiC wafers was prepared by dissolving organic acid, inorganic acid, and inorganic salt components in a solvent, and the specific components and contents were prepared as listed in Table 1.

[0047] organic acids Inorganic acid Inorganic salts menstruum 　 Organic acids used pKa Content (weight %) Inorganic acid used Content (weight %) Inorganic salt used Content (weight %) Solvents used Content Example 1 oxalic acid 1.25 0.2 sulfuric acid 0.1 - - water Remaining amount Example 2 oxalic acid 1.25 0.2 sulfuric acid 0.1 sodium sulfate 0.2 water Remaining amount Example 3 oxalic acid 1.25 0.2 hydrochloric acid 0.1 - water Remaining amount Example 4 oxalic acid 1.25 0.2 hydrochloric acid 0.1 sodium chloride 0.2 water Remaining amount Example 5 oxalic acid 1.25 0.2 nitric acid 0.1 - water Remaining amount Example 6 oxalic acid 1.25 0.2 nitric acid 0.1 sodium nitrate 0.2 water Remaining amount Example 7 oxalic acid 1.25 0.2 Phosphoric acid 0.1 - - water Remaining amount Example 8 tartaric acid 2.98 0.2 sulfuric acid 0.1 - - water Remaining amount Example 9 tartaric acid 2.98 0.2 sulfuric acid 0.1 sodium sulfate 0.2 water Remaining amount Comparative Example 1 oxalic acid 1.25 0.2 - - - - water Remaining amount Comparative Example 2 oxalic acid 1.25 0.2 - - sodium sulfate 0.2 water Remaining amount Comparative Example 3 oxalic acid 1.25 0.2 hydrofluoric acid 0.1 - - water Remaining amount Comparative Example 4 - - - sulfuric acid 0.1 - - water Remaining amount Comparative Example 5 - - - - - sodium sulfate 0.2 water Remaining amount Comparative Example 6 Ascorbic acid 4.17 0.2 - - - - water Remaining amount Comparative Example 7 Ascorbic acid 4.17 0.2 sulfuric acid 0.1 sodium sulfate 0.2 Remaining amount Comparative Example 8 Acetic acid 4.76 0.2 sulfuric acid 0.1 - - Remaining amount Comparative Example 9 citric acid 3.31 0.2 sulfuric acid 0.1 - - Remaining amount

[0049] Experimental Example 1: MnO 2 Solubility and stability evaluation

[0051] 20 g of each of the cleaning solution compositions of Examples 1 to 9 and Comparative Examples 1 to 9 were added to a 20 mL clear vial, and 0.4 g of MnO2 (Samjeon Sunyak, powder) was added to prepare a mixture. The prepared mixture was stirred by hand shaking and then treated with ultrasound (Hwashin Tech, POWERSONIC 420) for 10 minutes. After leaving it at room temperature, the solubility of MnO2 over time was evaluated, and the results are shown in Table 2. In addition, the reprecipitation of MnO2 was evaluated after leaving it at room temperature for 24 hours, and the results are shown in Table 2. The evaluation criteria used for each evaluation are as follows:

[0053] <MnO2용해성 평가 기준>

[0054] ◎: Solution becomes clear within 20 minutes;

[0055] ○: The solution becomes clear within 20 to 40 minutes;

[0056] △: The solution becomes translucent after 40 minutes or more;

[0057] X: There is almost no change in the solution even after 40 minutes.

[0059] <MnO2재석출 평가 기준>

[0060] ○: No precipitation;

[0061] X: Precipitated.

[0063] MnO2 solubility Whether MnO2 reprecipitates Example 1 ◎ ○ Example 2 ◎ ○ Example 3 ◎ ○ Example 4 ◎ ○ Example 5 ◎ ○ Example 6 ◎ ○ Example 7 ◎ ○ Example 8 ○ ○ Example 9 ◎ ○ Comparative Example 1 △ X Comparative Example 2 △ X Comparative Example 3 △ X Comparative Example 4 X X Comparative Example 5 X X Comparative Example 6 △ X Comparative Example 7 ○ X Comparative Example 8 X X Comparative Example 9 △ X

[0065] Experimental Example 2: Evaluation of cleaning power against metal oxides

[0067] The solubility of CeO2 and SiO2, which are commonly used as abrasive components, was evaluated using the SiC wafer cleaning compositions of Examples 1, 2, 4, and 5. The evaluation method was conducted in the same manner as the solubility evaluation method of MnO2 in Experimental Example 1. The comparison results are shown in Table 3.

[0069] item Cleaning power by type of abrasive material MnO2 CeO2 SiO2 Example 1 ◎ X X Example 2 ◎ X X Example 4 ◎ X X Example 5 ◎ X X

[0071] The above results demonstrate that the composition of the present disclosure is specifically effective for removing abrasives containing manganese dioxide.

[0073] Experimental Example 3: Evaluation of Particle and Metal Removal from SiC Wafer Surface

[0075] A MnO2 slurry was prepared by dispersing 2 wt% of MnO2 in ultrapure water, and a bare SiC wafer was immersed in the prepared slurry for about 10 seconds. Afterward, the SiC wafer was removed from the slurry and dried in the air to prepare a SiC wafer contaminated with MnO2 particles.

[0076] Particle removal capability was evaluated using the cleaning solution compositions of Examples 1, 2, 4, 5, Comparative Example 6, and Comparative Example 9. A SiC wafer contaminated with prepared MnO2 particles was dipped in each cleaning solution for 20 minutes and ultrasonic cleaning was performed. The wafer treated with the cleaning solution was then treated with pure water for 1 minute and dried using N2. The number of particles on the dried SiC wafer was measured using an AOI (Ficontec CL1500) instrument, and the results are shown in Table 4. Particles larger than 0.3 μm were measured, and the particle removal rate was calculated as the difference in the number of particles measured before and after cleaning the wafer contaminated with MnO2 particles.

[0078] Particle removal capability evaluation results item Particle removal rate (%) Example 1 90 Example 2 95 Example 4 85 Example 5 95 Comparative Example 6 50 Comparative Example 9 45

[0080] In addition, the cleaning power for various metals was evaluated using the cleaning solution compositions of Example 1 and Comparative Example 6. For wafers dried after cleaning according to the previously described process, the residual amount of each metal component per wafer surface area (atoms / cm²) was measured using a TXRF (Rigaku TXRF-V310) instrument. 2 The unit) was analyzed and the results are shown in Table 5.

[0082] Metal cleaning power evaluation results Ingredients [10 10 atoms / cm 2 ] Comparative Example 6 Example 1 Ca 3.43 <2.6 Fe 14.9 12.95 Ni 3.89 3.30 Zn 22.97 18.68 S 23.38 14.75

[0084] Although embodiments have been described as above, those skilled in the art can apply various technical modifications and variations based on the above. For example, suitable results can be achieved even if the described technologies are combined or combined in different forms, or replaced or substituted by other components or equivalents.

[0085] Therefore, other implementations, other embodiments, and equivalents to the claims also fall within the scope of the claims set forth below.

Claims

Claim 1 A composition for cleaning SiC wafers polished by an abrasive containing manganese dioxide, wherein the composition is pK a A composition for cleaning SiC wafers comprising: an organic acid having less than 3; and an inorganic acid; wherein the organic acid is selected from the group consisting of dichloroacetic acid, oxalic acid, maleic acid, malonic acid, glutamic acid, arginine, glycine, pyruvic acid, tartaric acid, and combinations thereof, and the inorganic acid is selected from the group consisting of sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, and combinations thereof. Claim 2 delete Claim 3 delete Claim 4 A composition for cleaning SiC wafers according to claim 1, further comprising an inorganic salt as an ion stabilizer. Claim 5 A composition for cleaning SiC wafers according to claim 4, wherein the inorganic salt is selected from the group consisting of sodium sulfate, potassium sulfate, magnesium sulfate, ammonium sulfate, aluminum sulfate, sodium nitrate, potassium nitrate, ammonium nitrate, calcium nitrate, sodium chloride, magnesium chloride, calcium chloride, potassium chloride, ammonium chloride, sodium bromide, potassium bromide, sodium iodide, potassium iodide, and combinations thereof. Claim 6 A composition for cleaning SiC wafers according to claim 1, wherein the organic acid is included in an amount of 0.1% by weight or more and 50% by weight or less based on the weight of the total composition. Claim 7 A SiC wafer cleaning composition according to claim 1, wherein the inorganic acid is included in an amount of 0.1% by weight or more and 10% by weight or less based on the weight of the total composition. Claim 8 A SiC wafer cleaning composition according to claim 5, wherein the inorganic salt is included in an amount of 0.1% by weight or more and 10% by weight or less based on the weight of the total composition. Claim 9 A SiC wafer cleaning composition according to claim 1, wherein the pH of the cleaning composition is less than 3. Claim 10 A SiC wafer cleaning composition according to claim 1, wherein the pH of the cleaning composition is less than 2. Claim 11 A SiC wafer cleaning composition according to claim 1, wherein the pH of the cleaning composition is less than 1.5.