CN113192819A - Semiconductor wafer thinning method - Google Patents
Semiconductor wafer thinning method Download PDFInfo
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- CN113192819A CN113192819A CN202010034702.7A CN202010034702A CN113192819A CN 113192819 A CN113192819 A CN 113192819A CN 202010034702 A CN202010034702 A CN 202010034702A CN 113192819 A CN113192819 A CN 113192819A
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- semiconductor wafer
- depth
- grinding
- thinned
- thinning
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02002—Preparing wafers
- H01L21/02005—Preparing bulk and homogeneous wafers
- H01L21/02008—Multistep processes
- H01L21/0201—Specific process step
- H01L21/02013—Grinding, lapping
Abstract
The invention discloses a method for thinning a semiconductor wafer, which comprises the following steps: roughly grinding the surface to be thinned of the semiconductor wafer, wherein the depth of the rough grinding is a preset first depth; finely grinding the surface to be thinned of the semiconductor wafer, wherein the finely ground depth is a preset second depth; the second depth is less than the first depth; carrying out wet etching on the surface to be thinned of the semiconductor wafer by using an etching solution, wherein the etching depth is a third depth; the third depth is less than the second depth; the corrosive liquid comprises sulfuric acid, hydrofluoric acid and oxalic acid. The invention can rapidly etch the semiconductor wafer by using a small amount of corrosive liquid on the premise of ensuring the surface smoothness of the wafer, and greatly reduces the whole thinning operation time of the semiconductor wafer, thereby greatly reducing the thinning cost of the semiconductor wafer and improving the thinning efficiency.
Description
Technical Field
The invention relates to the technical field of semiconductors, in particular to a semiconductor wafer thinning method.
Background
A wafer refers to a substrate (also called a substrate) from which semiconductor transistors or integrated circuits are fabricated. With the continuous development of high density, high performance, miniaturization, and light weight of semiconductor chips, the thinning process of semiconductor wafers becomes increasingly important. At present, the thinning process of a semiconductor wafer mainly comprises the following steps: the wafer is thinned by wet etching with a chemical reagent, and the process flow needs a developing solution, a fixing solution and a large amount of acid reagent to carry out acid corrosion on the silicon wafer so as to achieve a certain required groove depth. The wet etching process is adopted to thin the semiconductor wafer, a large amount of chemical reagents are needed, and the environment is polluted; and the operation environment is harsh, the production period is long, the production cost is increased, and the efficiency is low.
Disclosure of Invention
In view of the above problems, an object of the present invention is to provide a method for thinning a semiconductor wafer, which can rapidly etch the semiconductor wafer with a small amount of etchant on the premise of ensuring the surface smoothness of the wafer, and greatly reduce the whole thinning operation time of the semiconductor wafer, thereby greatly reducing the thinning cost of the semiconductor wafer and improving the thinning efficiency.
In order to achieve the above object, an embodiment of the present invention provides a method for thinning a semiconductor wafer, including:
roughly grinding the surface to be thinned of the semiconductor wafer, wherein the depth of the rough grinding is a preset first depth;
finely grinding the surface to be thinned of the semiconductor wafer, wherein the finely ground depth is a preset second depth; the second depth is less than the first depth;
carrying out wet etching on the surface to be thinned of the semiconductor wafer by using an etching solution, wherein the etching depth is a third depth; the third depth is less than the second depth; the corrosive liquid comprises sulfuric acid, hydrofluoric acid and oxalic acid.
As an improvement of the scheme, the volume ratio of the sulfuric acid to the hydrofluoric acid to the oxalic acid is as follows: (6-8): (1-3): (0.5 to 1.5).
As an improvement of the scheme, the volume ratio of the sulfuric acid to the hydrofluoric acid to the oxalic acid is as follows: 7: 2: 1.
as an improvement of the above scheme, the rough grinding is performed on the surface to be thinned of the semiconductor wafer, specifically:
the surface to be thinned of the semiconductor wafer is roughly ground by a grinding wheel in a grinding mode that the downward feeding speed is 4-6 mu m/s and the rotating speed of the grinding wheel is 3500-45000 rpm.
As a modification of the above, in the rough grinding, the downfeed rate of the grinding wheel was 5 μm/s, and the rotational speed of the grinding wheel was 40000 rpm.
As an improvement of the above scheme, the fine grinding of the surface to be thinned of the semiconductor wafer specifically includes:
and (3) finely grinding the surface to be thinned of the semiconductor wafer by using a grinding wheel in a grinding mode that the downward feeding speed is 7-9 mu m/s and the rotating speed of the grinding wheel is 4500-55000 rpm.
As an improvement of the above scheme, when the fine grinding is carried out, the downward feeding speed of the grinding wheel is 8 μm/s, and the rotating speed of the grinding wheel is 50000 rpm.
As an improvement of the scheme, the temperature of the etching solution is 0-15 ℃, and the etching time of the semiconductor wafer is 3-5 minutes.
As an improvement of the above scheme, the first depth is 1mm, the second depth is 200um, and the third depth is 50-100 nm.
Compared with the prior art, the semiconductor wafer thinning method provided by the embodiment of the invention can be used for preliminarily thinning the semiconductor wafer in a coarse grinding mode, so that most of the thickness of the semiconductor wafer can be removed quickly; then, the semiconductor wafer is ground for the second time and thinned in a fine grinding mode, so that the surface of the semiconductor wafer can be polished, the smooth finish of the surface of the semiconductor wafer meets the requirement, and meanwhile, the semiconductor wafer can be thinned at a thinning speed higher than that of wet etching; finally, the small amount of the remaining reduced thickness of the semiconductor wafer can be quickly etched by using a small amount of etching solution, and the etching speed of the semiconductor wafer can be increased due to the adoption of the etching solution mainly prepared from sulfuric acid, hydrofluoric acid and oxalic acid. Therefore, the embodiment of the invention can rapidly etch the semiconductor wafer by using a small amount of corrosive liquid on the premise of ensuring the surface smoothness of the wafer, and greatly reduce the whole thinning operation time of the semiconductor wafer, thereby greatly reducing the thinning cost of the semiconductor wafer and improving the thinning efficiency.
Drawings
In order to more clearly illustrate the technical solution of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a process flow diagram of a method for thinning a semiconductor wafer according to an embodiment of the invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, an embodiment of the invention provides a method for thinning a semiconductor wafer, which includes the following steps:
s10, roughly grinding the surface to be thinned of the semiconductor wafer, wherein the depth of the rough grinding is a preset first depth;
s11, finely grinding the surface to be thinned of the semiconductor wafer, wherein the finely ground depth is a preset second depth; the second depth is less than the first depth;
s12, carrying out wet etching on the surface to be thinned of the semiconductor wafer by using an etching solution, wherein the etching depth is a third depth; the third depth is less than the second depth; the corrosive liquid comprises sulfuric acid, hydrofluoric acid and oxalic acid.
Compared with the prior art, the semiconductor wafer thinning method provided by the embodiment of the invention can be used for preliminarily thinning the semiconductor wafer in a coarse grinding mode, so that most of the thickness of the semiconductor wafer can be removed quickly; then, the semiconductor wafer is ground for the second time and thinned in a fine grinding mode, so that the surface of the semiconductor wafer can be polished, the smooth finish of the surface of the semiconductor wafer meets the requirement, and meanwhile, the semiconductor wafer can be thinned at a thinning speed higher than that of wet etching; finally, the small amount of the remaining reduced thickness of the semiconductor wafer can be quickly etched by using a small amount of etching solution, and the etching speed of the semiconductor wafer can be increased due to the adoption of the etching solution mainly prepared from sulfuric acid, hydrofluoric acid and oxalic acid. Therefore, the embodiment of the invention can rapidly etch the semiconductor wafer by using a small amount of corrosive liquid on the premise of ensuring the surface smoothness of the wafer, and greatly reduce the whole thinning operation time of the semiconductor wafer, thereby greatly reducing the thinning cost of the semiconductor wafer and improving the thinning efficiency.
It can be understood that the rough grinding target depth is greater than the fine grinding target depth, and the fine grinding target depth is greater than the etching depth of the etching solution, so that the semiconductor wafer can be thinned most quickly on the premise of ensuring the surface smoothness of the semiconductor wafer, and the semiconductor wafer can be quickly etched by using a smaller amount of the etching solution.
In the embodiment of the invention, the etching solution mainly prepared from sulfuric acid, hydrofluoric acid and oxalic acid is adopted, so that the etching solution has good etching speed on the semiconductor wafer. Specifically, the semiconductor wafer generally contains silicon, and hydrofluoric acid has a corrosion effect on silicon and can effectively corrode the semiconductor wafer; in addition, the sulfuric acid has stronger acidity and stronger oxidizability and corrosiveness than nitric acid and the like, and can form bubbles on the surface of the semiconductor wafer, so that the surface substances of the semiconductor wafer can fall off conveniently, and the surface of the semiconductor wafer can be quickly corroded conveniently. Therefore, the combination of the sulfuric acid and the hydrofluoric acid can greatly improve the etching speed of the surface of the semiconductor wafer. In addition, the oxalic acid mainly plays a role in neutralization, so that the sulfuric acid and the hydrofluoric acid can be well matched in the etching solution, and the etching solution can have good corrosivity for the semiconductor wafer.
Illustratively, the volume ratio of the sulfuric acid to the hydrofluoric acid to the oxalic acid is: (6-8): (1-3): (0.5 to 1.5). After the intensive research on the component proportion of the corrosive liquid by the inventor, the inventor finds that: when the volume ratio of the sulfuric acid to the hydrofluoric acid to the oxalic acid is: (6-8): (1-3): (0.5-1.5), the sulfuric acid can be good in corrosivity to the semiconductor wafer, and can form a large amount of stable bubbles, so that effective falling of substances on the surface of the semiconductor wafer is facilitated; the proportion can also ensure that hydrofluoric acid has good corrosivity on the surface of the semiconductor wafer, and ensure that the corrosion speed of the hydrofluoric acid on the surface of the semiconductor wafer can be matched with the falling speed of substances on the surface of the wafer caused by bubbles generated by sulfuric acid, and the corrosion speed of the hydrofluoric acid is not greatly higher than the falling speed of the substances on the surface of the wafer, so that the good corrosion speed on the surface of the wafer can be ensured; in addition, the proportion can also ensure that the oxalic acid has good neutralization effect, so that the hydrofluoric acid and the sulfuric acid can be well matched in the corrosive liquid.
Preferably, the volume ratio of the sulfuric acid to the hydrofluoric acid to the oxalic acid is: 7: 2: 1. the inventors of the present invention have conducted extensive studies to find that the etching solution having the above composition ratio can provide the best etching effect on semiconductor wafers.
In the embodiment of the present invention, for example, the rough grinding is performed on the surface to be thinned of the semiconductor wafer, specifically: the surface to be thinned of the semiconductor wafer is roughly ground by a grinding wheel in a grinding mode that the downward feeding speed is 4-6 mu m/s and the rotating speed of the grinding wheel is 3500-45000 rpm.
In the embodiment, the grinding method using the grinding wheel can perform rough grinding on the surface of the semiconductor wafer more quickly without damaging the semiconductor wafer. Specifically, in the rough grinding, the downfeed rate of the grinding wheel was 5 μm/s, and the grinding wheel rotation speed was 40000 rpm.
In the above embodiment of the invention, for example, the surface to be thinned of the semiconductor wafer is finely ground, specifically: and (3) finely grinding the surface to be thinned of the semiconductor wafer by using a grinding wheel in a grinding mode that the downward feeding speed is 7-9 mu m/s and the rotating speed of the grinding wheel is 4500-55000 rpm.
In the embodiment, the grinding mode of the grinding wheel is adopted, so that the surface of the semiconductor wafer can be ground more quickly and better. Specifically, in the case of fine grinding, the downward feed rate of the grinding wheel was 8 μm/s, and the rotational speed of the grinding wheel was 50000 rpm.
The surface of the semiconductor wafer may be ground or polished by other grinding methods, which are not limited in particular.
In the embodiment of the invention, the temperature of the etching solution is 0-15 ℃, and the etching time of the semiconductor wafer is 3-5 minutes, so that the semiconductor wafer can be well etched.
In the embodiment of the present invention, the first depth is 1mm, the second depth is 200um, and the third depth is 50-100 nm. The inventor finds out through intensive research that: under the condition that the thinning thickness of the semiconductor wafer is not changed, the semiconductor wafer can be quickly thinned by adopting the setting mode of the thinning depth, and meanwhile, the using amount of the corrosive liquid can be ensured to be less.
While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (9)
1. A method for thinning a semiconductor wafer is characterized by comprising the following steps:
roughly grinding the surface to be thinned of the semiconductor wafer, wherein the depth of the rough grinding is a preset first depth;
finely grinding the surface to be thinned of the semiconductor wafer, wherein the finely ground depth is a preset second depth; the second depth is less than the first depth;
carrying out wet etching on the surface to be thinned of the semiconductor wafer by using an etching solution, wherein the etching depth is a third depth; the third depth is less than the second depth; the corrosive liquid comprises sulfuric acid, hydrofluoric acid and oxalic acid.
2. The method of claim 1, wherein the volume ratio of the sulfuric acid to the hydrofluoric acid to the oxalic acid is: (6-8): (1-3): (0.5 to 1.5).
3. The method of claim 2, wherein the volume ratio of the sulfuric acid to the hydrofluoric acid to the oxalic acid is: 7: 2: 1.
4. the method of claim 1, wherein the rough grinding is performed on the surface to be thinned of the semiconductor wafer, specifically:
the surface to be thinned of the semiconductor wafer is roughly ground by a grinding wheel in a grinding mode that the downward feeding speed is 4-6 mu m/s and the rotating speed of the grinding wheel is 3500-45000 rpm.
5. The method of claim 4, wherein the rough grinding is performed at a wheel downfeed rate of 5 μm/s and a wheel speed of 40000 rpm.
6. The method for thinning a semiconductor wafer according to claim 1, wherein the surface to be thinned of the semiconductor wafer is finely ground, specifically:
and (3) finely grinding the surface to be thinned of the semiconductor wafer by using a grinding wheel in a grinding mode that the downward feeding speed is 7-9 mu m/s and the rotating speed of the grinding wheel is 4500-55000 rpm.
7. The method of claim 6, wherein the lapping is performed at a downward feed rate of 8 μm/s and at a wheel speed of 50000 rpm.
8. The method for thinning the semiconductor wafer according to claim 1, wherein the temperature of the etching solution is 0 to-15 ℃, and the etching time for the semiconductor wafer is 3 to 5 minutes.
9. The method of any one of claims 1-8, wherein the first depth is 1mm, the second depth is 200um, and the third depth is 50-100 nm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN202010034702.7A CN113192819A (en) | 2020-01-14 | 2020-01-14 | Semiconductor wafer thinning method |
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| CN202010034702.7A CN113192819A (en) | 2020-01-14 | 2020-01-14 | Semiconductor wafer thinning method |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115895663A (en) * | 2022-12-28 | 2023-04-04 | 昆山金城试剂有限公司 | Silicon corrosive agent |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115895663A (en) * | 2022-12-28 | 2023-04-04 | 昆山金城试剂有限公司 | Silicon corrosive agent |
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Application publication date: 20210730 |