CN110957207A - Pre-sand blasting pretreatment method for P heavily doped silicon wafer - Google Patents
Pre-sand blasting pretreatment method for P heavily doped silicon wafer Download PDFInfo
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- CN110957207A CN110957207A CN201911081149.6A CN201911081149A CN110957207A CN 110957207 A CN110957207 A CN 110957207A CN 201911081149 A CN201911081149 A CN 201911081149A CN 110957207 A CN110957207 A CN 110957207A
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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
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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
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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
- H01L21/02041—Cleaning
- H01L21/02043—Cleaning before device manufacture, i.e. Begin-Of-Line process
- H01L21/02052—Wet cleaning only
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- Condensed Matter Physics & Semiconductors (AREA)
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- Manufacturing & Machinery (AREA)
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- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Cleaning Or Drying Semiconductors (AREA)
- Mechanical Treatment Of Semiconductor (AREA)
Abstract
The invention provides a pretreatment method before sand blasting of a P heavily doped silicon wafer, which comprises the following steps of A mixed acid corrosion: putting the P heavily doped silicon wafer into a silicon wafer containing HF and HNO3Performing acid etching for 40-80 s at 40-50 ℃ in the liquid medicine tank, and then cleaning with deionized water; b, alkali washing: b, mounting the silicon wafer processed in the step A on a cam mechanism in an alkaline washing tank, wherein the rotating speed is 60-80 RPM; the alkaline washing tank is filled with 5-10% by volume of strong alkali solution, the washing temperature is 40-60 ℃, and the washing time is 3-9 min. According to the invention, the strong alkali washing step is added before the sand blasting treatment of the back surface of the silicon wafer, so that the generation of mark residues is effectively avoided in the following sand blasting treatment process, and the production rejection rate is reduced to zero through the verification of actual production.
Description
Technical Field
The invention belongs to the technical field of silicon wafer back damage sand blasting treatment, and particularly relates to a pretreatment method for a P heavily doped silicon wafer before sand blasting.
Background
Metal ion impurities in silicon can significantly reduce minority carrier lifetime and further affect the performance of silicon devices. Therefore, in the process of processing the silicon wafer, one of the working procedures is back damage, namely sand blasting process treatment is carried out on the back surface of the silicon wafer. The back of the silicon wafer is mechanically damaged through a sand blasting process to form a soft damage layer, so that the silicon wafer has the gettering capability, and the particle effect on the surface of the silicon polished wafer caused by the gettering process is solved from the gettering mechanism.
The common sand blasting method is to mix SIC powder and water according to a certain proportion and stir the mixture evenly to form grinding fluid, and then carry out sand blasting treatment on the back of the silicon wafer through a back damage device according to the set parameter requirements. After the sand blasting treatment is finished, the vacuum chuck is adopted to suck the silicon wafer, and then the grinding fluid remained on the silicon wafer is cleaned by cleaning the machine table.
When the sucker adsorbs the silicon wafer, the grinding liquid corresponding to the area of the sucker is adsorbed on the sucker and taken away, so that the silicon wafer forms a cleaner area in the area, and the shape of the cleaner area is consistent with that of the sucker.
For certain doping types of wafers, the chuck clamping operation has no effect on the back side of the wafer. However, after a heavily doped silicon wafer with a dopant of P in the <111> crystal orientation is cleaned, an outer ring of dark black mark residue is formed on the surface of the silicon wafer at the position adsorbed by the sucker, and the mark is not effectively removed at present and can only be treated as a waste product.
Disclosure of Invention
The invention aims to solve the technical problems, and provides a pretreatment method before sand blasting aiming at the problem that marks are easily generated in the back sand blasting process of a <111> crystal orientation and P heavily doped silicon wafer, so that the marks are eliminated after sand blasting.
The invention provides a pretreatment method for a P heavily doped silicon wafer before sand blasting, which comprises the following steps:
A. mixed acid etching
Putting the P heavily doped silicon wafer into a silicon wafer containing HF and HNO3Performing acid etching for 40-80 s at 40-50 ℃ in the liquid medicine tank, and then cleaning with deionized water;
B. alkali washing
B, mounting the silicon wafer processed in the step A on a cam mechanism in an alkaline washing tank, wherein the rotating speed is 60-80 RPM; the alkaline washing tank is filled with 5-10% by volume of strong alkali solution, the washing temperature is 40-60 ℃, and the washing time is 3-9 min.
In the invention, the acid etching process belongs to the conventional process in the sand blasting process; the alkali washing process is creative work for avoiding marks on the back surface of a silicon wafer after a sand blasting process, and the working principle is as follows: the alkaline liquid medicine is cleaned, so that a slight oxidation protective film is formed on the surface of the silicon wafer, and the protective film can be removed in subsequent cleaning, thereby avoiding the adsorption mark residue.
The concentration of the alkali liquor, the cleaning temperature and the cleaning time are strictly limited, experiments prove that the corresponding technical effect cannot be achieved when the concentration of the alkali liquor is too low (lower than 5%), the cleaning temperature is too low (lower than 40 ℃) or the cleaning time is too short (less than 3min), but if the concentration of the alkali liquor is too high (more than 10%), the cleaning temperature is too high (higher than 60 ℃) and the cleaning time is too long (more than 9min), although the marks of the sucking discs can be avoided, other defects which cannot be eliminated can be caused, such as black spots which cannot be removed.
Preferably, in the pretreatment method before sandblasting of the P-heavily doped silicon wafer provided by the invention, in the solution of mixed acid in the liquid medicine tank of the step a, HF and HNO are added3The volume ratio of (1: 2) to (1: 6), and the acidic etching can be achieved within the concentration range, preferably 1: 6.
Preferably, in the pretreatment method before sandblasting of the P-heavily doped silicon wafer provided by the invention, the strong base solution is a NaOH or KOH solution, and the volume fraction of the NaOH or KOH is preferably 6.25%.
Preferably, in the pretreatment method before sandblasting of the P heavily doped silicon wafer provided by the invention, the cleaning temperature is 40 ℃. In order to avoid defects caused by high-temperature cleaning, the cleaning temperature is as high as possible, but the minimum temperature is about 40 ℃, and the mark removing effect cannot be achieved if the temperature is lower.
Preferably, in the pretreatment method before the sandblasting of the P-heavily doped silicon wafer provided by the invention, the rotating speed of the cam mechanism is 70 RPM. In the present invention, the cam mechanism is available in the prior art and is available commercially. When the silicon chip is installed, the silicon chip is installed in the silicon chip groove, and then the silicon chip groove is installed on the cam.
Preferably, in the pretreatment method before the sandblasting of the P heavily doped silicon wafer provided by the invention, the cleaning time is preferably 6 min.
Further, the invention also provides a P heavily doped silicon wafer sand blasting method, which comprises the following working procedures: a pretreatment process, which is a pretreatment method before sand blasting of the P heavily doped silicon wafer; and a sand blasting procedure, wherein a back damage device and grinding fluid are adopted to perform sand blasting treatment on the surface of the silicon wafer to form a metal gettering center.
The invention has the following beneficial guarantee and effects:
according to the invention, the strong alkali washing step is added before the sand blasting treatment of the back surface of the silicon wafer, so that the generation of mark residues is effectively avoided in the following sand blasting treatment process, and the production rejection rate is reduced to zero through the verification of actual production.
Detailed Description
The present invention will now be described in detail with reference to examples, but the practice of the present invention is not limited thereto.
Example one
The pretreatment method before sandblasting for the P-heavily doped silicon wafer provided by the embodiment comprises two working procedures of mixed acid corrosion and alkaline washing, and the specific implementation mode of each working procedure is as follows:
A. mixed acid etching
Putting the P heavily doped silicon wafer into a silicon wafer containing HF and HNO3In the liquid medicine tank, wherein HF and HNO3Is 1:2, acid etching is carried out for 80s at the temperature of 40 ℃, and then deionized water is used for cleaning.
B. Alkali washing
B, mounting the silicon chip processed in the step A on a cam mechanism in an alkaline washing tank, wherein the rotating speed is 60 RPM; the alkaline washing tank is filled with NaOH solution with volume fraction of 5%, the washing temperature is 40 ℃, and the washing time is 9 min.
The cleaning temperature in this embodiment is a preferred cleaning temperature. In order to avoid defects caused by high-temperature cleaning, the cleaning temperature is as high as possible, but the minimum temperature is about 40 ℃, and the mark removing effect cannot be achieved if the temperature is lower.
Cam mechanisms exist in the prior art and are commercially available. When the silicon chip is installed, the silicon chip is installed in the silicon chip groove, and then the silicon chip groove is installed on the cam.
Example two
A. Mixed acid etching
Putting the P heavily doped silicon wafer into a silicon wafer containing HF and HNO3In the liquid medicine tank, wherein HF and HNO3Is 1:6, is subjected to acid etching at the temperature of 45 ℃ for 60s, and is then cleaned by deionized water.
B. Alkali washing
B, mounting the silicon chip processed in the step A on a cam mechanism in an alkaline washing tank, wherein the rotating speed is 70 RPM; the alkaline washing tank is filled with 6.25 percent by volume of NaOH solution, the washing temperature is 40 ℃, and the washing time is 6 min.
The process parameters in this embodiment belong to the optimal parameter combination, and experiments verify that the number of silicon wafers that do not produce marks is the largest under the pretreatment condition.
EXAMPLE III
A. Mixed acid etching
Putting the P heavily doped silicon wafer into a silicon wafer containing HF and HNO3In the liquid medicine tank, wherein HF and HNO3Is 1:4, acid etching is carried out for 40s at the temperature of 50 ℃, and then deionized water is used for cleaning.
B. Alkali washing
B, mounting the silicon wafer processed in the step A on a cam mechanism in an alkaline washing tank, wherein the rotating speed is 80 RPM; the alkaline washing tank is filled with KOH solution with the volume fraction of 8 percent, the washing temperature is 60 ℃, and the washing time is 3 min.
The cleaning temperature in this embodiment is the highest cleaning temperature that can be used, above which, although no chuck marks are produced after the blasting process, other non-removable defects, such as the formation of non-removable black spots, can occur.
Further, the invention also provides a P heavily doped silicon wafer sand blasting method, which comprises the following working procedures: a pretreatment process, which is a pretreatment method before sand blasting of the P heavily doped silicon wafer in any one of the three embodiments; and a sand blasting procedure, wherein a back damage device and grinding fluid are adopted to perform sand blasting treatment on the surface of the silicon wafer to form a metal gettering center, and specific process parameters are the same as those of the prior art and can be obtained by referring to the prior art.
While the preferred embodiments of the present invention have been described in detail, it will be understood by those skilled in the art that the invention is not limited thereto, and that various changes and modifications may be made without departing from the spirit of the invention, and the scope of the appended claims is to be accorded the full scope of the invention.
Claims (7)
1. A pretreatment method before sandblasting of a P heavily doped silicon wafer is characterized in that the pretreatment is carried out before sandblasting of the back surface of the P heavily doped silicon wafer, and the pretreatment method comprises the following steps:
A. mixed acid etching
Putting the P heavily doped silicon wafer into a silicon wafer containing HF and HNO3Performing acid etching for 40-80 s at 40-50 ℃ in the liquid medicine tank, and then cleaning with deionized water;
B. alkali washing
B, mounting the silicon wafer processed in the step A on a cam mechanism in an alkaline washing tank, wherein the rotating speed is 60-80 RPM; the alkaline washing tank is filled with 5-10% by volume of strong alkali solution, the washing temperature is 40-60 ℃, and the washing time is 3-9 min.
2. The pre-sandblasting pretreatment method for the P-heavily doped silicon wafer as claimed in claim 1, wherein:
wherein, in the liquid medicine groove mixed acid solution of the step A, HF and HNO3The volume ratio of (A) to (B) is 1:2 to 1: 6.
3. The pre-sandblasting pretreatment method for the P-heavily doped silicon wafer as claimed in claim 1, wherein:
wherein, in the step B, the strong base solution is NaOH or KOH solution, and the volume fraction of NaOH or KOH is 6.25%.
4. The pre-sandblasting pretreatment method for the P-heavily doped silicon wafer as claimed in claim 1, wherein:
wherein, in the step B, the cleaning temperature is 40 ℃.
5. The pre-sandblasting pretreatment method for the P-heavily doped silicon wafer as claimed in claim 1, wherein:
in step B, the rotating speed of the cam mechanism is 70 RPM.
6. The pre-sandblasting pretreatment method for the P-heavily doped silicon wafer as claimed in claim 1, wherein:
wherein, in the step B, the cleaning time is 6 min.
7. A P heavily doped silicon wafer sand blasting method is characterized by comprising the following steps:
a pretreatment step of performing pretreatment before sandblasting on the P heavily doped silicon wafer according to any one of claims 1 to 6;
and a sand blasting procedure, wherein a back damage device and grinding fluid are adopted to perform sand blasting treatment on the surface of the silicon wafer to form a metal gettering center.
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| CN106544641A (en) * | 2016-10-21 | 2017-03-29 | 上海交通大学 | Prepare the sandblasting pretreatment method of hard alloy substrate diamond coatings |
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| CN108493270A (en) * | 2018-03-14 | 2018-09-04 | 江西比太科技有限公司 | A kind of alkali cleaning dry method process for etching |
| CN109148265A (en) * | 2018-08-10 | 2019-01-04 | 横店集团东磁股份有限公司 | A kind of solar energy polycrystal RIE prepares the cleaning process before black silicon |
| CN109585583A (en) * | 2018-12-03 | 2019-04-05 | 江苏中宇光伏科技有限公司 | A kind of process for etching for solar battery sheet production |
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2019
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Patent Citations (7)
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| JP2005340643A (en) * | 2004-05-28 | 2005-12-08 | Sharp Corp | Manufacturing method of semiconductor substrate for solar cell |
| CN104404627A (en) * | 2014-10-24 | 2015-03-11 | 苏州阿特斯阳光电力科技有限公司 | Surface pretreatment process before crystalline silicon RIE fleece making |
| CN106544641A (en) * | 2016-10-21 | 2017-03-29 | 上海交通大学 | Prepare the sandblasting pretreatment method of hard alloy substrate diamond coatings |
| CN108080233A (en) * | 2016-11-23 | 2018-05-29 | 佛山市顺德区美的电热电器制造有限公司 | The production method and cookware of cookware graduation mark |
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