CN116884836A - Back silicon corrosion processing method of silicon-based wafer - Google Patents
Back silicon corrosion processing method of silicon-based wafer Download PDFInfo
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- CN116884836A CN116884836A CN202310605020.0A CN202310605020A CN116884836A CN 116884836 A CN116884836 A CN 116884836A CN 202310605020 A CN202310605020 A CN 202310605020A CN 116884836 A CN116884836 A CN 116884836A
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- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims abstract description 141
- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 141
- 239000010703 silicon Substances 0.000 title claims abstract description 141
- 238000005260 corrosion Methods 0.000 title claims abstract description 53
- 230000007797 corrosion Effects 0.000 title claims abstract description 53
- 238000003672 processing method Methods 0.000 title claims abstract description 8
- 239000002253 acid Substances 0.000 claims abstract description 80
- 239000007788 liquid Substances 0.000 claims abstract description 40
- 238000000034 method Methods 0.000 claims abstract description 35
- DDFHBQSCUXNBSA-UHFFFAOYSA-N 5-(5-carboxythiophen-2-yl)thiophene-2-carboxylic acid Chemical compound S1C(C(=O)O)=CC=C1C1=CC=C(C(O)=O)S1 DDFHBQSCUXNBSA-UHFFFAOYSA-N 0.000 claims abstract description 32
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims abstract description 31
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 29
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 23
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims abstract description 22
- 239000012295 chemical reaction liquid Substances 0.000 claims abstract description 18
- 238000004140 cleaning Methods 0.000 claims abstract description 16
- 235000012239 silicon dioxide Nutrition 0.000 claims abstract description 11
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 11
- 238000001035 drying Methods 0.000 claims abstract description 5
- 235000012431 wafers Nutrition 0.000 claims description 126
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 26
- 239000011261 inert gas Substances 0.000 claims description 18
- 238000002791 soaking Methods 0.000 claims description 11
- 238000007664 blowing Methods 0.000 claims description 10
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 8
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 7
- 229910017604 nitric acid Inorganic materials 0.000 claims description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 6
- 229960000583 acetic acid Drugs 0.000 claims description 4
- 239000012362 glacial acetic acid Substances 0.000 claims description 4
- 238000005507 spraying Methods 0.000 claims description 4
- 239000008367 deionised water Substances 0.000 claims description 3
- 229910021641 deionized water Inorganic materials 0.000 claims description 3
- 229910052757 nitrogen Inorganic materials 0.000 claims description 3
- 238000011010 flushing procedure Methods 0.000 claims description 2
- 239000002184 metal Substances 0.000 abstract description 16
- 238000005530 etching Methods 0.000 abstract description 12
- 230000001590 oxidative effect Effects 0.000 abstract description 6
- 239000004809 Teflon Substances 0.000 description 33
- 229920006362 Teflon® Polymers 0.000 description 33
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 29
- 230000000052 comparative effect Effects 0.000 description 10
- 238000001514 detection method Methods 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 230000005587 bubbling Effects 0.000 description 3
- 238000009434 installation Methods 0.000 description 3
- 229910004298 SiO 2 Inorganic materials 0.000 description 2
- 230000002159 abnormal effect Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000001465 metallisation Methods 0.000 description 2
- 238000005192 partition Methods 0.000 description 2
- 238000004064 recycling Methods 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 238000004378 air conditioning Methods 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 229910021421 monocrystalline silicon Inorganic materials 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 229910021420 polycrystalline silicon Inorganic materials 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
Classifications
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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
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
- H01L21/306—Chemical or electrical treatment, e.g. electrolytic etching
- H01L21/30604—Chemical etching
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
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- Condensed Matter Physics & Semiconductors (AREA)
- Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
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Abstract
A back surface silicon corrosion processing method of a silicon-based wafer comprises the following steps: mounting the silicon-based wafer on a corrosion-resistant carrier, and exposing the back surface of the silicon-based wafer to the surface of the corrosion-resistant carrier; immersing the corrosion-resistant carrier in a mixed acid solution, oxidizing the surface of the silicon-based wafer by using the mixed acid solution, and forming silicon dioxide on the surface of the silicon-based wafer; taking out the corrosion-resistant carrier from the mixed acid solution and cleaning the silicon-based wafer; immersing the corrosion-resistant carrier in an oxidation reaction liquid, wherein the oxidation reaction liquid comprises ammonium fluoride and hydrogen peroxide; taking out the corrosion-resistant carrier from the oxidation reaction liquid, and putting the corrosion-resistant carrier into a corrosion liquid to be soaked to dissolve the silicon dioxide, wherein the corrosion liquid comprises ammonium fluoride and hydrofluoric acid; and cleaning and spin-drying the silicon-based wafer on the corrosion-resistant carrier, and taking down the silicon-based wafer. The invention can remove the oxynitride layer on the surface of the silicon-based wafer in the back silicon etching process of the silicon-based wafer, thereby reducing the shedding of deposited back metal and lowering the rejection rate of chips.
Description
Technical Field
The invention belongs to the field of silicon-based wafer processing, and particularly relates to a back silicon corrosion processing method of a silicon-based wafer.
Background
The silicon-based wafer is a thin silicon-based wafer obtained by melting and pulling a single crystal silicon ingot from polycrystalline silicon by photoengraving, grinding, polishing, slicing, and the like, and finally slicing the silicon ingot, which is produced by purifying 99.999% of silicon element. Is a base material for manufacturing ICs. In the manufacture of discrete device chips, after the backside thinning of the silicon-based wafer is completed, backside metal is deposited as an electrode so that leads can be attached to the backside metal during packaging. Because the silicon-based wafer has internal stress and micro-cracks after the back surface is thinned, the internal stress of the chip is released by further eliminating the micro-cracks through a back surface silicon corrosion process after the back surface is thinned, so that the toughness of the chip is improved. The existing silicon etching process for the back surface of a silicon-based wafer mainly comprises two parts, wherein the first step is to oxidize silicon on the surface of the silicon-based wafer by using mixed acid containing nitric acid to form silicon-containing oxide (mainly silicon dioxide), and the second step is to dissolve the silicon dioxide generated in the first part by using etching solution containing hydrofluoric acid and ammonium fluoride. The problems with this process are: in the first step, when silicon and nitric acid are subjected to oxidation reaction, a plurality of oxynitride can be synchronously formed, and the oxynitride is difficult to react with the corrosive liquid in the second step and remain on the back surface of the silicon-based wafer, so that the combination of a deposited metal layer and a silicon basal plane is blocked in the back metal deposition process, the metal layer is easy to fall off, and the rejection rate of chips is improved. Therefore, how to develop a new back side silicon etching process for silicon-based wafers to overcome the above problems is a direction that those skilled in the art need further research.
Disclosure of Invention
The invention aims to provide a back silicon corrosion processing method of a silicon-based wafer, which is used for removing an oxynitride layer on the surface of the silicon-based wafer in the back silicon corrosion process of the silicon-based wafer, so that the falling-off of deposited back metal is reduced, and the rejection rate of chips is reduced.
The technical scheme provided by the invention is a back silicon corrosion processing method of a silicon-based wafer, which comprises the following steps:
step 100: mounting a silicon-based wafer on a corrosion-resistant carrier, and exposing the back surface of the silicon-based wafer to the surface of the corrosion-resistant carrier;
step 200: immersing the corrosion-resistant carrier in a mixed acid solution, and controlling the corrosion-resistant carrier to rotate in the mixed acid solution so as to oxidize the surface of the silicon-based wafer by the mixed acid solution and form silicon dioxide on the surface of the silicon-based wafer;
step 300: taking out the corrosion-resistant carrier from the mixed acid solution, and cleaning the silicon-based wafer on the corrosion-resistant carrier;
step 400: immersing the corrosion-resistant carrier in an oxidation reaction liquid, wherein the oxidation reaction liquid comprises ammonium fluoride and hydrogen peroxide;
step 500: taking the corrosion-resistant carrier out of the oxidation reaction liquid, and soaking the carrier in a corrosive liquid to dissolve the silicon dioxide, wherein the corrosive liquid comprises ammonium fluoride and hydrofluoric acid;
step 600: and cleaning and spin-drying the silicon-based wafer on the corrosion-resistant carrier, and taking the silicon-based wafer off the corrosion-resistant carrier.
Preferably, the step 100 includes: at least 2 silicon-based wafers are mounted on the corrosion-resistant carrier with a spacing between adjacent silicon-based wafers of at least 9.3mm.
Preferably, the step 200 includes:
the mixed acid solution comprises nitric acid, glacial acetic acid and hydrofluoric acid, the rotating speed of the rotation is 2-6 rpm, and the duration of soaking in the mixed acid solution is 3-5 minutes; the liquid temperature of the mixed acid liquid is 7-9 ℃.
Preferably, the step 300 further includes: and (3) blowing inert gas into the mixed acid liquid from which the corrosion-resistant carrier is taken out.
Preferably, the step 300 includes: the volume of the mixed acid loaded in the acid liquor pool is 95-105L, the inert gas is pure nitrogen, and the speed of blowing the inert gas is 1-1.5m 3 /h。
Preferably, the step 300 includes: and the step of blowing the inert gas is to continuously blow the inert gas into the mixed acid liquid until the color of the mixed acid liquid appears white.
Preferably, the step 400 includes: the oxidation reaction liquid comprises a hydrogen peroxide solution with the concentration of 30-32%, an ammonium fluoride solution with the concentration of 39-41% and water, wherein the volume ratio of the hydrogen peroxide solution to the ammonium fluoride solution to the water is 2:2:6, soaking in the oxidation reaction liquid for 2-10 minutes.
Preferably, the step 300 includes: the cleaning comprises the steps of continuously flushing the silicon-based wafer for 5 times in a manner of overflow, quick discharge spraying, water inlet spraying and overflow by deionized water.
Preferably, the step 300 includes: and maintaining the corrosion-resistant carrier to continuously rotate in the process of cleaning the silicon-based wafer.
Preferably, the step 500 includes: and (3) putting the corrosion-resistant carrier into corrosive liquid to be soaked for 4-6 minutes.
Compared with the prior art, the invention has the following advantages:
firstly, the invention aims at the oxynitride layer generated by mixed acid in the process of oxidizing the surface of the silicon substrate wafer, and the oxynitride layer is stripped from the surface of the silicon substrate wafer by further reacting with oxidizing liquid comprising hydrogen peroxide and ammonium fluoride, so that the shedding of deposited back metal is reduced, and the rejection rate of chips is reduced.
In addition, the invention reduces the heat generated in the oxidation reaction process of the step 200 and increases the fluidity of the mixed acid solution between the adjacent wafers by increasing the intervals between the adjacent wafers on the corrosion-resistant carrier, so that the nitrogen oxides generated in the step 200 are more dissolved in the mixed acid solution, and the nitrogen oxide layer on the surface of the wafer is reduced.
Third, compared with the traditional process, the temperature of the mixed acid solution in the step 200 is reduced, and more nitrogen oxides generated in the step 200 are dissolved in the mixed acid solution.
Fourth, inert gas is blown into the mixed acid solution, and the volatilization of the nitrogen oxides dissolved in the mixed acid solution in a gas form is accelerated through a bubbling effect, so that the concentration of the nitrogen oxides dissolved in the mixed acid solution is reduced, and the mixed acid solution is beneficial to recycling of the processing of multi-batch silicon-based wafers.
Finally, the invention has simple operation process and is easy to realize by manual or semi-automatic program.
Drawings
Fig. 1 is a schematic flow chart of example 1.
Detailed Description
Other advantages and effects of the present invention will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present invention with reference to specific examples. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention.
Example 1, please refer to fig. 1:
a back surface silicon corrosion processing method of a silicon-based wafer comprises the following steps:
step 100: selecting a Teflon wafer frame with the model of A182-60MB-0215 as a corrosion-resistant carrier, mounting a silicon-based wafer in a mounting groove of the Teflon wafer frame, and exposing the back surface of the silicon-based wafer to the opening side of the mounting groove;
step 200: immersing the Teflon sheet frame in a mixed acid solution, and controlling the Teflon sheet frame to rotate in the mixed acid solution; wherein the mixed acid solution comprises nitric acid, glacial acetic acid and hydrofluoric acid, the rotating speed of the rotation is 2-6 rpm, and the time period of soaking in the mixed acid solution is 3-5 minutes;
step 300: taking out the Teflon sheet frame from the mixed acid solution and cleaning the silicon-based wafer on the Teflon sheet frame;
step 400: placing the Teflon sheet frame into an oxidation reaction liquid for soaking for 2-10 minutes, wherein the oxidation reaction liquid comprises ammonium fluoride and hydrogen peroxide;
step 500: taking the Teflon sheet frame out of the oxidation reaction liquid, and putting the Teflon sheet frame into corrosive liquid for soaking for 4-6 minutes, wherein the corrosive liquid comprises ammonium fluoride and hydrofluoric acid;
step 600: and cleaning and spin-drying the silicon-based wafer on the Teflon sheet frame, and taking the silicon-based wafer off the Teflon sheet frame.
By adopting the technical scheme: firstly, oxidizing the surface of a silicon-based wafer fixed on a Teflon sheet frame by mixed acid, oxidizing silicon on the surface of the wafer to generate silicon dioxide, and decomposing nitric acid in the mixed acid to generate nitric oxide in the process, wherein the following reaction formula is shown in the specification:
3Si+4HNO 3 →3SiO 2 +4NO+2H 2 O
Si+4HNO 3 →SiO 2 +4NO 2 +2H 2 O
2NO 2 →N 2 O 4
such oxynitride is partially dissolved in the mixed acid and washed away in step 300, and another portion forms an oxynitride layer that continues to adhere to the surface of the silicon-based wafer. Next, the silicon-based wafer is soaked in an oxidation reaction liquid comprising ammonium fluoride and hydrogen peroxide, and a further oxidation reaction is carried out on the oxynitride layer on the surface of the silicon-based wafer, see the following reaction formula:
H 2 O 2 +N 2 O 4 →2HNO 3
after the oxynitride layer is stripped from the surface of the silicon-based wafer, dissolving silicon dioxide on the surface of the silicon-based wafer by using an etching solution comprising ammonium fluoride and hydrofluoric acid, wherein the following reaction formula is shown:
SiO 2 +6HF→H 2 SiF 6 +2H 2 O
and finally, the back silicon corrosion processing of the silicon-based wafer is completed.
In this example, the step 100 further includes: and installing at least 2 silicon-based wafers on the Teflon wafer frame in a mode of arranging partition groove installation, wherein the partition groove installation means that 1 empty installation groove is arranged between every two adjacent silicon-based wafers. Such that the spacing between adjacent silicon-based wafers is at least 9.3mm.
By adopting the technical scheme: the first aspect reduces the total number of silicon-based wafers reacted in a single pass into the mixed acid solution, thereby reducing the heat generated in the process of oxidizing the surface of the silicon-based wafers with the mixed acid solution, and further reducing the liquid temperature of the mixed acid solution. The solubility of the oxynitride in the acid liquid is reduced along with the rise of the liquid temperature, so that the dissolution rate of the oxynitride in the mixed acid liquid generated in the process is improved by reducing the liquid temperature of the mixed acid liquid, and the thickness of the oxynitride layer formed by the oxynitride adhered on the surface of the silicon-based wafer is reduced. The second aspect increases the interval between the adjacent silicon-based wafers, thereby improving the fluidity of the mixed acid solution between the adjacent silicon-based wafers, enabling the heat generated in the reaction process of the mixed acid solution and the silicon-based wafers to be conducted away from the surfaces of the silicon-based wafers more quickly, further reducing the local temperature of the mixed acid solution near the surfaces of the silicon-based wafers, and playing the role of improving the dissolution rate of the oxynitride in the mixed acid solution and reducing the thickness of the oxynitride layer formed by the adhesion of the oxynitride on the surfaces of the silicon-based wafers.
In this example, the liquid temperature of the mixed acid liquid is 7 to 9 ℃.
By adopting the technical scheme: compared with the traditional process, the temperature of the mixed acid solution for the silicon oxide-based wafer is reduced (the temperature of the mixed acid solution in the traditional process is generally set to be 17-21 ℃), so that the heat generated in the oxidation reaction process is counteracted with the lower temperature of the mixed acid solution, and more nitrogen oxides generated in the step 200 are dissolved in the mixed acid solution.
In this example, the step 300 further includes: and (3) blowing inert gas into the mixed acid liquid taken out of the Teflon sheet frame.
By adopting the technical scheme: the nitrogen oxides dissolved in the mixed acid liquid are accelerated to volatilize in a gas form through the bubbling effect, so that the concentration of the nitrogen oxides dissolved in the mixed acid liquid is reduced, the mixed acid liquid is beneficial to recycling in the process of multi-batch silicon-based wafers, and the nitrogen oxide concentration in the mixed acid liquid is prevented from increasing continuously.
In this example, theStep 300 includes: the volume of the mixed acid loaded in the acid liquor pool is 95-105L, the inert gas is pure nitrogen, and the speed of blowing the inert gas is 1-1.5m 3 And/h. A kind of electronic device with high-pressure air-conditioning system: and the step of blowing the inert gas is to continuously blow the inert gas into the mixed acid liquid until the color of the mixed acid liquid appears white.
In this example, in the step 400: the oxidation reaction solution consists of a hydrogen peroxide solution with the concentration of 30-32%, an ammonium fluoride solution with the concentration of 39-41% and water, wherein the volume ratio of the hydrogen peroxide solution to the ammonium fluoride solution to the water is 2:2:6.
in this example, the cleaning in step 300 means that deionized water is continuously flushed for 5 times in a manner of overflow, quick-drain spray, water inlet spray, and overflow. And during this process the teflon wafer holder is kept rotating.
Comparative example 1:
comparative example 1 is a conventional silicon etching method for processing the back surface of a silicon-based wafer, comprising the following steps:
step 100: mounting a silicon-based wafer in a mounting groove of a Teflon wafer frame, and exposing the back surface of the silicon-based wafer to the opening side of the mounting groove;
step 200: immersing the Teflon sheet frame in a mixed acid solution, and controlling the Teflon sheet frame to rotate in the mixed acid solution; wherein the mixed acid solution comprises nitric acid, glacial acetic acid and hydrofluoric acid, the rotating speed of the rotation is 2-6 rpm, and the time period of soaking in the mixed acid solution is 3-5 minutes;
step 300: taking out the Teflon sheet frame from the mixed acid solution and cleaning the silicon-based wafer on the Teflon sheet frame;
step 400: taking the Teflon sheet frame out of the cleaning tank, and putting the Teflon sheet frame into corrosive liquid for soaking for 4-6 minutes, wherein the corrosive liquid comprises ammonium fluoride and hydrofluoric acid;
step 500: and cleaning and spin-drying the silicon-based wafer on the Teflon sheet frame, and taking the silicon-based wafer off the Teflon sheet frame.
The inventors conducted comparative tests on 100 groups of example 1 and comparative example 1, and the results are shown in table 1 below:
| wafer backside hydrophilicity | Wafer surface color difference rate | Metal falling rate after dicing | |
| Example 1 | 0％ | 0％ | 0％ |
| Comparative example 1 | 0％ | 10％ | 15％ |
TABLE 1
The wafer back hydrophilicity refers to the proportion of the silicon-based wafer back subjected to back silicon corrosion processing, which shows the hydrophilicity after being soaked in water. Specifically: when the silicon dioxide cannot be effectively removed from the surface of the silicon-based wafer, the surface of the wafer shows hydrophilic characteristics; on the contrary, the water-removing property is exhibited.
The wafer surface heterochromatic rate refers to the rate that abnormal color appears on the back surface of the silicon-based wafer after back surface silicon corrosion processing through naked eyes. When the color of the back surface of the silicon-based wafer appears as normal gray, the back surface of the silicon-based wafer is not attached with the oxynitride layer or is only attached with a few oxynitride layers; otherwise, the back surface of the silicon-based wafer may exhibit an abnormal yellow color.
The metal falling rate after dicing refers to the ratio of falling of the metal layer from the back surface of the silicon-based wafer after dicing the silicon-based wafer after back surface metallization processing, and the data visually reflects the rejection rate of the silicon-based wafer.
From the above detection results we can conclude that: in contrast to the prior art corresponding to comparative example 1: the silicon-based wafer with back silicon etched by the scheme of embodiment 1 has significantly improved removal rate of oxynitride layer and chip yield.
Example 2:
example 2 differs from example 1 in that in this example:
a silicon-based wafer is mounted in each mounting groove on the teflon sheet rack, namely: in this example, the gaps between adjacent silicon-based wafers mounted on the teflon wafer frames are gaps between adjacent mounting grooves, and the number of silicon-based wafers mounted on the teflon wafer frames is twice that in embodiment 1.
Example 3 differs from example 1 in that in this example:
the number of silicon-based wafers mounted on the teflon sheet frame was the same as in example 1, and the silicon-based wafers were mounted in each of the adjacent mounting grooves on a certain side of the teflon sheet frame. Namely: in this example silicon-based wafers are centrally mounted in a dense arrangement in one side of the teflon wafer holder.
The inventors performed comparative tests on 100 groups of examples 1 to 3, and the results are shown in Table 2 below:
| wafer backside hydrophilicity | Wafer surface color difference rate | Metal falling rate after dicing | |
| Example 1 | 0％ | 0％ | 0％ |
| Example 2 | 0％ | 9％ | 12％ |
| Example 3 | 0％ | 5％ | 8％ |
TABLE 2
From the above detection results we can conclude that:
the silicon-based wafer after back side silicon etching processing is realized by the schemes of embodiments 2 and 3, and the removal rate of the oxynitride layer and the chip yield of the back side of the silicon-based wafer are optimized compared with the prior art, but the yield is lower than that of embodiment 1 because the silicon-based wafer is arranged on the Teflon wafer frame in a dense manner.
Example 4:
example 4 differs from example 1 in that: in the step 400: the oxidation reaction solution consists of 30-32% of hydrogen peroxide solution, 39-41% of ammonium fluoride solution and water, wherein the volume ratio of the hydrogen peroxide solution to the ammonium fluoride solution to the water is 2:2:5.
example 5:
example 5 differs from example 1 in that: in the step 400: the oxidation reaction solution consists of 30-32% of hydrogen peroxide solution, 39-41% of ammonium fluoride solution and water, wherein the volume ratio of the hydrogen peroxide solution to the ammonium fluoride solution to the water is 2:2:7.
example 6:
example 6 differs from example 1 in that: in the step 400: the oxidation reaction solution consists of 30-32% of hydrogen peroxide solution, 39-41% of ammonium fluoride solution and water, wherein the volume ratio of the hydrogen peroxide solution to the ammonium fluoride solution to the water is 3:2:6.
example 7:
example 7 differs from example 1 in that: in the step 400: the oxidation reaction solution consists of 30-32% of hydrogen peroxide solution, 39-41% of ammonium fluoride solution and water, wherein the volume ratio of the hydrogen peroxide solution to the ammonium fluoride solution to the water is 1:2:6.
example 8:
example 8 differs from example 1 in that: in the step 400: the oxidation reaction solution consists of 30-32% of hydrogen peroxide solution, 39-41% of ammonium fluoride solution and water, wherein the volume ratio of the hydrogen peroxide solution to the ammonium fluoride solution to the water is 2:3:6.
example 9:
example 9 differs from example 1 in that: in the step 400: the oxidation reaction solution consists of 30-32% of hydrogen peroxide solution, 39-41% of ammonium fluoride solution and water, wherein the volume ratio of the hydrogen peroxide solution to the ammonium fluoride solution to the water is 2:1:6.
the inventors performed comparative tests on 100 groups of examples 1, 4-9, and the results are shown in Table 3 below:
| wafer backside hydrophilicity | Wafer surface color difference rate | Metal falling rate after dicing | |
| Example 1 | 0％ | 0％ | 0％ |
| Example 4 | 0％ | 1.1％ | 1.8％ |
| Example 5 | 0％ | 2.4％ | 3.5％ |
| Example 6 | 0％ | 1.3％ | 1.5％ |
| Example 7 | 0％ | 2.1％ | 4.5％ |
| Example 8 | 0％ | 2.5％ | 4.4％ |
| Example 9 | 0％ | 1.7％ | 2.2％ |
TABLE 3 Table 3
From the above detection results we can conclude that:
the silicon-based wafer after back side silicon etching process realized by the embodiments 4 to 9 has an optimized removal rate of oxynitride layer and chip yield on the back side of the silicon-based wafer compared with the prior art, but when the volume ratio of hydrogen peroxide solution, ammonium fluoride solution and water is 2:2:6, the technical effect obtained by the specific proportion is the most optimal when the specific proportion is used as an oxidation reaction liquid.
Example 10:
example 10 differs from example 1 in that: the mixed acid solution in step 200 has a solution temperature of 15 ℃.
The inventors performed comparative tests on 100 groups of example 1 and example 10, and the results are shown in table 4 below:
| wafer backside hydrophilicity | Wafer surface color difference rate | Metal falling rate after dicing | |
| Example 1 | 0％ | 0％ | 0％ |
| Example 10 | 0％ | 3％ | 3.5％ |
TABLE 4 Table 4
From the above detection results we can conclude that:
the silicon-based wafer with back silicon etching process realized by the solution of embodiment 10 has optimized removal rate of oxynitride layer and chip yield on the back of the silicon-based wafer compared with the prior art, but when the liquid temperature of the mixed acid solution in step 200 is at the temperature defined in embodiment 1, the metal falling rate after dicing is better than the metal falling rate after dicing at 15-17 ℃ in the prior art.
Example 11:
example 11 differs from example 1 in that: step 300 in this example does not include bubbling an inert gas through the mixed acid solution from which the teflon sheet rack was removed.
The inventors carried out comparative detection of back side silicon etching processing of 4 continuous silicon-based wafers in a continuous operation state by taking 100 groups of example 1 and example 11, and the results are shown in the following table 5:
| wafer backside hydrophilicity | Wafer surface color difference rate | Metal falling rate after dicing | |
| Example 1-round 1 | 0％ | 0％ | 0％ |
| Examples 1-2 nd round | 0％ | 0％ | 0％ |
| Examples 1 to 3 rd wheel | 0％ | 0％ | 0％ |
| Examples 1 to 4 th wheel | 0％ | 0％ | 0％ |
| Example 11-round 1 | 0％ | 0％ | 0％ |
| Example 11-round 2 | 0％ | 0％ | 0％ |
| Examples 11 to 3 rd round | 0％ | 0.3％ | 0.5％ |
| Examples 11-4 th wheel | 0％ | 0.5％ | 0.7％ |
TABLE 5
From the above detection results we can conclude that: the removal rate of the oxynitride layer and the chip yield of the silicon-based wafer after the back silicon etching process achieved by the solution of embodiment 11 are optimized compared with the prior art, but the step 300 does not adopt a technical step of blowing inert gas into the mixed acid solution from which the teflon sheet frame is taken out, so that the concentration of the dissolved oxynitride in the mixed acid solution is gradually increased, and further, the chip yield of the mixed acid solution is gradually reduced in the subsequent rounds of back silicon etching process of the silicon-based wafer.
The embodiments of the present invention have been described in detail above with reference to the drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, it is within the scope of the appended claims and their equivalents to fall within the scope of the invention.
Claims (10)
1. A back silicon corrosion processing method of a silicon-based wafer is characterized by comprising the following steps:
step 100: mounting a silicon-based wafer on a corrosion-resistant carrier, and exposing the back surface of the silicon-based wafer to the surface of the corrosion-resistant carrier;
step 200: immersing the corrosion-resistant carrier in a mixed acid solution, and controlling the corrosion-resistant carrier to rotate in the mixed acid solution so as to oxidize the surface of the silicon-based wafer by the mixed acid solution and form silicon dioxide on the surface of the silicon-based wafer;
step 300: taking out the corrosion-resistant carrier from the mixed acid solution, and cleaning the silicon-based wafer on the corrosion-resistant carrier;
step 400: immersing the corrosion-resistant carrier in an oxidation reaction liquid, wherein the oxidation reaction liquid comprises ammonium fluoride and hydrogen peroxide;
step 500: taking the corrosion-resistant carrier out of the oxidation reaction liquid, and soaking the carrier in a corrosive liquid to dissolve the silicon dioxide, wherein the corrosive liquid comprises ammonium fluoride and hydrofluoric acid;
step 600: and cleaning and spin-drying the silicon-based wafer on the corrosion-resistant carrier, and taking the silicon-based wafer off the corrosion-resistant carrier.
2. The method of claim 1, wherein the step 100 includes:
at least 2 silicon-based wafers are mounted on the corrosion-resistant carrier with a spacing between adjacent silicon-based wafers of at least 9.3mm.
3. The method of claim 1, wherein the step 200 includes:
the mixed acid solution comprises nitric acid, glacial acetic acid and hydrofluoric acid, the rotating speed of the rotation is 2-6 rpm, and the duration of soaking in the mixed acid solution is 3-5 minutes; the liquid temperature of the mixed acid liquid is 7-9 ℃.
4. The method of claim 1, wherein the step 300 comprises: and (3) blowing inert gas into the mixed acid liquid from which the corrosion-resistant carrier is taken out.
5. The method of claim 4, wherein said step 300 comprises: the volume of the mixed acid loaded in the acid liquor pool is 95-105L, the inert gas is pure nitrogen, and the speed of blowing the inert gas is 1-1.5m 3 /h。
6. The method of claim 5, wherein said step 300 comprises:
and the step of blowing the inert gas is to continuously blow the inert gas into the mixed acid liquid until the color of the mixed acid liquid appears white.
7. The method of claim 1, wherein the step 400 includes:
the oxidation reaction liquid comprises a hydrogen peroxide solution with the concentration of 30-32%, an ammonium fluoride solution with the concentration of 39-41% and water, wherein the volume ratio of the hydrogen peroxide solution to the ammonium fluoride solution to the water is 2:2:6, soaking in the oxidation reaction liquid for 2-10 minutes.
8. The method of claim 1, wherein the step 300 comprises:
the cleaning comprises the steps of continuously flushing the silicon-based wafer for 5 times in a manner of overflow, quick discharge spraying, water inlet spraying and overflow by deionized water.
9. The method of claim 1, wherein the step 300 comprises: and maintaining the corrosion-resistant carrier to continuously rotate in the process of cleaning the silicon-based wafer.
10. The method of claim 1, wherein the step 500 includes: and (3) putting the corrosion-resistant carrier into corrosive liquid to be soaked for 4-6 minutes.
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