Process method for processing wafer surface

Abstract

The invention discloses a process method for processing the surface of a wafer. The process method comprises the following steps: thinning the wafer; after the thinning process is carried out on the wafer, the surface of the wafer is treated through at least one of the following chemical treatment processes, so that wafer surface defects occurring in the subsequent wet etching process are reduced; the at least one chemical treatment process comprises the following steps of: 1, removing an oxide layer on the surface of the wafer through dilute hydrofluoric acid; a process II: oxidizing and repairing the surface of the wafer by filling oxygen or ozone into water; 3, removing residues on the surface of the wafer through sulfuric acid and hydrogen peroxide; process 4: removing particles on the surface of the wafer and changing the surface property of the wafer through ammonia water, hydrogen peroxide and water; and carrying out wet etching on the wafer. After the wafer is thinned, a series of chemical process treatment is carried out, so that the surface defects of the wafer can be reduced after the wafer is subjected to wet etching.

Description

Technical Field

[0001] The present invention relates to the field of semiconductors, and in particular to a process for processing a wafer surface. Background Art

[0002] After chemical mechanical polishing (or other thinning processes), the surface roughness and properties of the wafer surface change, such as the surface changes from hydrophilic to hydrophobic, the surface is too rough, or by-products remain. Figure 1 As shown, these defects are usually difficult to capture, resulting in various defects in subsequent wet etching, such as block etch, surface tiny particles (tiny PA), silicon residue, and roughness, making it difficult to obtain good surface uniformity, affecting product yield and performance. Summary of the invention

[0003] Based on the problems existing in the prior art, the present invention provides a process method for processing the surface of a wafer, comprising: after the wafer is subjected to a thinning process, the surface of the wafer is treated by at least one of the following chemical treatment processes to reduce wafer surface defects that occur in a subsequent wet etching process; the at least one chemical treatment process comprises: process one: removing the oxide layer on the surface of the wafer by dilute hydrofluoric acid; process two: oxidizing and repairing the surface of the wafer by filling water with oxygen or ozone; process three: removing residues on the surface of the wafer by sulfuric acid and hydrogen peroxide; process four: removing particles on the surface of the wafer and changing the surface properties of the wafer by ammonia water, hydrogen peroxide and water; and wet etching the wafer.

[0004] In some embodiments, the process 1: removing the oxide layer on the surface of the wafer by dilute hydrofluoric acid includes: the concentration of the dilute hydrofluoric acid is 45~55% HF and the volume ratio of water is 1:10~1:2000; the immersion time is 10s~300s.

[0005] In some embodiments, the process 2: repairing the wafer surface by oxidation by filling water with oxygen or ozone includes: the concentration of oxygen or ozone is 5PPM~85PPM; the immersion time is 10s~300s.

[0006] In some embodiments, the process three: removing residues on the wafer surface by sulfuric acid and hydrogen peroxide includes: the concentration of sulfuric acid and hydrogen peroxide is 90~99% sulfuric acid and 25~35% hydrogen peroxide; the volume ratio of sulfuric acid and hydrogen peroxide is 1:2~10:1; and the immersion time is 10s~300s.

[0007] In some embodiments, process four: removing particles on the wafer surface and changing the surface properties of the wafer by ammonia, hydrogen peroxide and water includes: the concentrations of ammonia, hydrogen peroxide and water are: 25~35% ammonia, 25~35% hydrogen peroxide and the volume of water accounts for the range of: 0.5%-8%, 0.5%-16%, 99%-76% respectively; the immersion time is 10s~180s.

[0008] In some embodiments, the steps of the at least one chemical treatment process are: first perform process one, then perform process two, then perform process three, and then perform process four.

[0009] In some embodiments, the steps of the at least one chemical treatment process are: first perform process two, then perform process one, and then perform process three.

[0010] In some embodiments, the steps of the at least one chemical treatment process are: first perform process one, then perform process two, and then perform process four.

[0011] In some embodiments, the steps of the at least one chemical treatment process are: first perform process three, then perform process two, then perform process one, then perform process three, and then perform process two.

[0012] In some embodiments, the thinning process is chemical mechanical polishing.

[0013] The technical solution of the present invention can reduce surface defects of the wafer after the wafer is wet-etched by performing a series of chemical processes after the wafer is thinned. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of the morphology of the wafer surface after the wafer surface is wet-etched without being processed.

[0015] Figure 2 The present invention is a flowchart of a method for processing a wafer surface according to an embodiment of the present invention.

[0016] Figure 3 It is a schematic diagram of the wetting angle of the wafer surface after wet etching before and after the wafer surface is processed by the wafer processing process according to the embodiment of the present invention.

[0017] Figure 4 It is a schematic diagram of the morphology of the wafer surface after the wafer surface is processed by the wafer processing process according to an embodiment of the present invention and then wet-etched. DETAILED DESCRIPTION

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some examples or embodiments of the present invention. For ordinary technicians in this field, the present invention can also be applied to other similar scenarios based on these drawings without creative work. Unless it is obvious from the language environment or otherwise explained, the same reference numerals in the figures represent the same structure or operation.

[0019] Figure 2 The present invention is a flowchart of a process method for processing a wafer surface according to an embodiment of the present invention, the method comprising: S1: thinning the wafer; S2: after the wafer is subjected to a thinning process (e.g., chemical mechanical polishing), treating the wafer surface by at least one of the following chemical treatment processes to reduce wafer surface defects that may occur in a subsequent wet etching process; the at least one chemical treatment process comprises: process one: removing an oxide layer on the wafer surface by using dilute hydrofluoric acid; process two: repairing the wafer surface by oxidizing and filling water with oxygen or ozone; process three: removing residues on the wafer surface by using sulfuric acid and hydrogen peroxide; process four: removing particles on the wafer surface and changing the surface properties of the wafer by using ammonia, hydrogen peroxide and water; S3: wet etching the wafer.

[0020] Specifically, in one embodiment, removing the oxide layer on the surface of the wafer by using dilute hydrofluoric acid includes: the concentration of the dilute hydrofluoric acid is 45-55% HF and the volume ratio of water is 1:10-1:2000; the immersion time is 10s-300s. Specifically, the concentration of the dilute hydrofluoric acid can be 49% HF.

[0021] Specifically, in one embodiment, the process of repairing the wafer surface by oxidation by filling water with oxygen or ozone includes: the concentration of oxygen or ozone is 5PPM to 85PPM; and the immersion time is 10s to 300s.

[0022] Specifically, in one embodiment, removing the residue on the surface of the wafer by sulfuric acid and hydrogen peroxide includes: the concentration of sulfuric acid and hydrogen peroxide is 90-99% sulfuric acid and 25-35% hydrogen peroxide; the volume ratio of sulfuric acid and hydrogen peroxide is 1:2-10:1; and the immersion time is 10s-300s. Specifically, the concentration of sulfuric acid and hydrogen peroxide is 96% sulfuric acid and 31% hydrogen peroxide.

[0023] Specifically, in one embodiment, the removal of wafer surface particles and the change of wafer surface properties by ammonia, hydrogen peroxide and water include: the concentrations of ammonia, hydrogen peroxide and water are: 25-35% ammonia, 25-35% hydrogen peroxide and the volume of water accounts for 0.5%-8%, 0.5%-16%, 99%-76% respectively; the immersion time is 10s-180s. Specifically, the concentrations of ammonia and hydrogen peroxide are: 29% ammonia and 31% hydrogen peroxide.

[0024] Figure 3 It is a comparison of the wetting angle of the wafer surface before and after wet etching before and after the wafer surface is processed by the above-mentioned wafer processing process. Figure 3 (a) is the wetting angle of the wafer surface after wet etching without any treatment on the wafer surface; Figure 3 (b) is a schematic diagram of the wetting angle of the wafer surface after wet etching without the wafer surface being treated; and a schematic diagram of the wetting angle of the wafer surface after wet etching after the wafer surface treatment process described above. After the wafer surface treatment method of the present invention, the wetting angle of the wafer surface after wet etching is reduced.

[0025] Figure 4 The figure is a schematic diagram of the morphology of the wafer surface after the wafer surface is treated by the above-mentioned wafer treatment process and then wet-etched. After the wafer surface treatment method of the present invention, the defects on the wafer surface after wet etching are significantly reduced.

[0026] The process method for processing a wafer surface provided by the present invention can be applied to the field of image sensors. For example, when chemical mechanical polishing is performed on the back side of a back-illuminated image sensor, defects on the back side of the substrate can be reduced, thereby improving the performance of the image sensor.

[0027] It should be noted that, for the above-mentioned process one, process two, process three and process four, the embodiments of the present invention can be combined according to different environments and process conditions, and the process sequence can be flexibly controlled. The following are several embodiments of the present invention.

[0028] In one embodiment, process one may be performed first: removing the oxide layer on the surface of the wafer by using dilute hydrofluoric acid; then process two may be performed: repairing the surface of the wafer by oxidizing it by filling water with oxygen or ozone; then process three may be performed: removing residues on the surface of the wafer by using sulfuric acid and hydrogen peroxide; then process four may be performed: removing particles on the surface of the wafer and changing the surface properties of the wafer by using ammonia, hydrogen peroxide and water.

[0029] In one embodiment, process two may be performed first: repairing the wafer surface by oxidizing it by filling water with oxygen or ozone; then process one may be performed: removing the oxide layer on the wafer surface by using dilute hydrofluoric acid; and then process three may be performed: removing residues on the wafer surface by using sulfuric acid and hydrogen peroxide.

[0030] In one embodiment, process one may be performed first: removing the oxide layer on the surface of the wafer by using dilute hydrofluoric acid; then process two may be performed: repairing the surface of the wafer by oxidizing it by filling water with oxygen or ozone; and then process four may be performed: removing particles on the surface of the wafer and changing the surface properties of the wafer by using ammonia water, hydrogen peroxide and water.

[0031] In one embodiment, process three can be performed first: removing residues on the wafer surface by using sulfuric acid and hydrogen peroxide; then process two can be performed: repairing the wafer surface by filling water with oxygen or ozone for oxidation; then process one can be performed: removing the oxide layer on the wafer surface by using dilute hydrofluoric acid; then process three can be performed: removing residues on the wafer surface by using sulfuric acid and hydrogen peroxide; then process two can be performed: repairing the wafer surface by filling water with oxygen or ozone for oxidation.

[0032] The basic concepts have been described above. Obviously, for those skilled in the art, the above detailed disclosure is only for example and does not constitute a limitation of the present invention. Although it is not explicitly stated here, those skilled in the art may make various modifications, improvements and corrections to the present invention. Such modifications, improvements and corrections are suggested in the present invention, so such modifications, improvements and corrections still belong to the spirit and scope of the exemplary embodiments of the present invention. It should be understood that the embodiments described in the present invention are only used to illustrate the principles of the embodiments of the present invention. Other variations may also fall within the scope of the present invention. Therefore, as an example and not a limitation, the alternative configurations of the embodiments of the present invention may be considered to be consistent with the teachings of the present invention. Accordingly, the embodiments of the present invention are not limited to the embodiments explicitly introduced and described in the present invention.

Claims

1. A process for processing a wafer surface, characterized in that: include: Thinning the wafer; After the wafer is subjected to the thinning process, the surface of the wafer is treated by at least one of the following chemical treatment processes to reduce wafer surface defects that may occur in a subsequent wet etching process; The at least one chemical treatment process comprises: Process 1: Remove the oxide layer on the surface of the wafer using dilute hydrofluoric acid; Process 2: Oxidation and repair of the wafer surface by filling water with oxygen or ozone; Process 3: Removing residues from the wafer surface using sulfuric acid and hydrogen peroxide; Process 4: Removing particles from the wafer surface and changing the surface properties of the wafer using ammonia, hydrogen peroxide and water; The wafer is wet-etched.

2. The method according to claim 1, characterized in that The process 1: removing the oxide layer on the surface of the wafer by using dilute hydrofluoric acid comprises: The concentration of dilute hydrofluoric acid is 45~55% HF to water volume ratio 1:10~1:2000; the immersion time is 10s~300s.

3. The method according to claim 1, characterized in that The second process of repairing the wafer surface by filling water with oxygen or ozone oxidation includes: The concentration of oxygen or ozone is 5PPM~85PPM; the immersion time is 10s~300s.

4. The method according to claim 1, characterized in that Process 3: Removing residues from the wafer surface by sulfuric acid and hydrogen peroxide includes: The concentration of sulfuric acid and hydrogen peroxide is 90~99% sulfuric acid and 25~35% hydrogen peroxide; the volume ratio of sulfuric acid to hydrogen peroxide is 1:2~10:1; and the immersion time is 10s~300s.

5. The method according to claim 1, characterized in that Process 4: Removing particles from the wafer surface and changing the wafer surface properties by using ammonia, hydrogen peroxide and water includes: The concentrations of ammonia water, hydrogen peroxide, and water are: 25~35% ammonia water, 25~35% hydrogen peroxide, and the volume ranges of water are: 0.5%-8%, 0.5%-16%, and 99%-76%, respectively; the immersion time is 10s~180s.

6. The method according to claim 1, characterized in that The steps of the at least one chemical treatment process are: First execute process one, then execute process two, then execute process three, and then execute process four.

7. The method according to claim 1, characterized in that The steps of the at least one chemical treatment process are: First execute process 2, then execute process 1, and then execute process 3.

8. The method according to claim 1, characterized in that The steps of the at least one chemical treatment process are: First execute process one, then execute process two, and then execute process four.

9. The method according to claim 1, characterized in that The steps of the at least one chemical treatment process are: First execute process three, then execute process two, then execute process one, then execute process three, then execute process two.

10. The method according to claim 1, characterized in that The thinning process is chemical mechanical polishing.

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