CN110600363A - Method for removing silicon oxide and method for manufacturing semiconductor device - Google Patents
Method for removing silicon oxide and method for manufacturing semiconductor device Download PDFInfo
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- CN110600363A CN110600363A CN201910882548.6A CN201910882548A CN110600363A CN 110600363 A CN110600363 A CN 110600363A CN 201910882548 A CN201910882548 A CN 201910882548A CN 110600363 A CN110600363 A CN 110600363A
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- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 title claims abstract description 106
- 229910052814 silicon oxide Inorganic materials 0.000 title claims abstract description 105
- 238000000034 method Methods 0.000 title claims abstract description 47
- 239000004065 semiconductor Substances 0.000 title claims abstract description 29
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 22
- 238000005530 etching Methods 0.000 claims abstract description 62
- 238000002791 soaking Methods 0.000 claims abstract description 15
- 238000011010 flushing procedure Methods 0.000 claims abstract description 6
- 239000000243 solution Substances 0.000 claims description 123
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims description 74
- 239000006227 byproduct Substances 0.000 claims description 36
- 230000002093 peripheral effect Effects 0.000 claims description 20
- 239000003929 acidic solution Substances 0.000 claims description 11
- 239000007788 liquid Substances 0.000 claims description 10
- 239000000126 substance Substances 0.000 claims description 7
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 6
- 239000011259 mixed solution Substances 0.000 claims description 5
- 238000004140 cleaning Methods 0.000 claims description 4
- 238000005498 polishing Methods 0.000 claims description 4
- 229910052739 hydrogen Inorganic materials 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 2
- 235000012431 wafers Nutrition 0.000 description 116
- 239000000047 product Substances 0.000 description 9
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 6
- 229910052710 silicon Inorganic materials 0.000 description 6
- 239000010703 silicon Substances 0.000 description 6
- 239000000758 substrate Substances 0.000 description 6
- 239000012212 insulator Substances 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- 229910000577 Silicon-germanium Inorganic materials 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- LEVVHYCKPQWKOP-UHFFFAOYSA-N [Si].[Ge] Chemical compound [Si].[Ge] LEVVHYCKPQWKOP-UHFFFAOYSA-N 0.000 description 3
- 238000003860 storage Methods 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229910052732 germanium Inorganic materials 0.000 description 2
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 description 2
- 230000002209 hydrophobic effect Effects 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000007517 polishing process Methods 0.000 description 2
- JBRZTFJDHDCESZ-UHFFFAOYSA-N AsGa Chemical compound [As]#[Ga] JBRZTFJDHDCESZ-UHFFFAOYSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- GPXJNWSHGFTCBW-UHFFFAOYSA-N Indium phosphide Chemical compound [In]#P GPXJNWSHGFTCBW-UHFFFAOYSA-N 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- AXQKVSDUCKWEKE-UHFFFAOYSA-N [C].[Ge].[Si] Chemical compound [C].[Ge].[Si] AXQKVSDUCKWEKE-UHFFFAOYSA-N 0.000 description 1
- HMDDXIMCDZRSNE-UHFFFAOYSA-N [C].[Si] Chemical compound [C].[Si] HMDDXIMCDZRSNE-UHFFFAOYSA-N 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- RPQDHPTXJYYUPQ-UHFFFAOYSA-N indium arsenide Chemical compound [In]#[As] RPQDHPTXJYYUPQ-UHFFFAOYSA-N 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 229910021420 polycrystalline silicon Inorganic materials 0.000 description 1
- 229920005591 polysilicon Polymers 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000005389 semiconductor device fabrication Methods 0.000 description 1
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Chemical compound [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 230000003068 static effect Effects 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
- H01L21/02041—Cleaning
- H01L21/02043—Cleaning before device manufacture, i.e. Begin-Of-Line process
- H01L21/02052—Wet cleaning only
-
- 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
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- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Manufacturing & Machinery (AREA)
- Computer Hardware Design (AREA)
- Physics & Mathematics (AREA)
- Power Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Cleaning Or Drying Semiconductors (AREA)
- Weting (AREA)
Abstract
The invention provides a method for removing silicon oxide and a method for manufacturing a semiconductor device, wherein the method for removing the silicon oxide comprises the following steps: providing a wafer, wherein the surface of the wafer is provided with a silicon oxide layer to be removed; soaking the wafer in a first etching solution to remove most of the silicon oxide layer; and taking the wafer out of the first etching solution, placing the wafer in a rotating state, and flushing the surface of the wafer by adopting a second etching solution to remove the residual silicon oxide layer. The technical scheme of the invention can completely remove the silicon oxide layer, and avoids influencing the electrical property of the product, thereby avoiding reducing the yield of the product.
Description
Technical Field
The present invention relates to the field of integrated circuit manufacturing, and more particularly, to a method for removing silicon oxide and a method for manufacturing a semiconductor device.
Background
In the existing production process of a 55nm Micro Controller Unit (MCU), the height of the storage region is greater than that of the peripheral region, and in order to avoid the storage region being ground in the subsequent chemical mechanical grinding process, a layer of silicon oxide with a certain thickness is deposited on the peripheral region to balance the height difference between the storage region and the peripheral region. After the cmp process, the silicon oxide needs to be removed to avoid affecting the electrical parameters of the subsequent devices.
At present, batch wafers are usually soaked in hydrofluoric acid tank for a long time to etch and remove silicon oxide. However, the wafer surface after the hydrofluoric acid soaking is hydrophobic, and has strong activity and instability, so that a byproduct (fluosilicic acid) of a reaction between hydrofluoric acid and silicon oxide is easily adsorbed and adheres back to the surface of the wafer, and the amount of the generated byproduct adhering back to the surface of the wafer is increased along with the increase of the soaking time in a hydrofluoric acid tank, and the residue of the byproduct of the silicon oxide reaction affects the electrical parameters of the device, so that the defect rate of the chip is increased.
Therefore, it is an urgent need to solve the problem of completely removing the silicon oxide and the by-products generated by the reaction of the silicon oxide and the hydrofluoric acid to avoid affecting the yield of the product.
Disclosure of Invention
The invention aims to provide a method for removing silicon oxide and a method for manufacturing a semiconductor device, which can completely remove the silicon oxide layer, avoid influencing the electrical property of a product and further avoid reducing the yield of the product.
To achieve the above object, the present invention provides a method for removing silicon oxide, comprising:
providing a wafer, wherein the surface of the wafer is provided with a silicon oxide layer to be removed;
soaking the wafer in a first etching solution to remove most of the silicon oxide layer;
and taking the wafer out of the first etching solution, placing the wafer in a rotating state, and flushing the surface of the wafer by adopting a second etching solution to remove the residual silicon oxide layer.
Optionally, the first etching solution and the second etching solution are both acidic solutions.
Optionally, the first etching solution and the second etching solution are acidic solutions with the same components and concentrations.
Optionally, the acidic solution comprises a hydrofluoric acid solution, and the HF and H in the hydrofluoric acid solution2The volume ratio of O is 1: 100-1: 20.
Optionally, when the wafer is immersed in the first etching solution, ultrasonic vibration is accompanied.
Optionally, after the wafer is taken out from the first etching solution and before the wafer is rinsed with the second etching solution, and/or after the wafer is rinsed with the second etching solution, the surface of the wafer is subjected to hydrophilic treatment to remove byproducts that adhere back to the surface of the wafer.
Optionally, the surface of the wafer is cleaned by using a SC1 solution, a SC2 solution, or a SC1 solution and a SC2 solution in sequence to perform hydrophilic treatment on the surface of the wafer, wherein the SC1 solution is NH4OH、H2O2And H2O, the SC2 solution is HCl and H2O2And H2And (3) a mixed solution of O.
Optionally, NH in the SC1 solution4OH、H2O2And H2The volume ratio of O is 1:2: 100-1: 2: 40; HCl and H in the SC2 solution2O2And H2The volume ratio of O is 1:2: 100-1: 2: 40.
The present invention also provides a method for manufacturing a semiconductor device, comprising: the silicon oxide layer on the surface of a wafer is removed by adopting the method for removing the silicon oxide provided by the invention.
Optionally, the wafer includes a core region and a peripheral region, and a top surface of the core region is higher than a top surface of the peripheral region.
Optionally, the silicon oxide layer is formed on the wafer, and the wafer is subjected to chemical mechanical polishing to expose the top surface of the core region, where the top surface of the core region is flush with the top surface of the silicon oxide layer on the peripheral region.
Optionally, the semiconductor device includes a memory array, and the core region is a memory region where the memory array is located.
Compared with the prior art, the technical scheme of the invention has the following beneficial effects:
1. the method for removing the silicon oxide comprises the steps of soaking a wafer with a silicon oxide layer to be removed on the surface in first etching liquid to remove most of the silicon oxide layer; and taking the wafer out of the first etching liquid and placing the wafer in a rotating state, and flushing the surface of the wafer by adopting a second etching liquid to remove the residual silicon oxide layer, so that the silicon oxide layer can be completely removed, the electrical property of the product is prevented from being influenced, and the reduction of the yield of the product is avoided.
2. According to the manufacturing method of the semiconductor device, the silicon oxide layer on the surface of the wafer is removed by adopting the method for removing the silicon oxide, so that the core area of the wafer is prevented from being damaged in the manufacturing process of the semiconductor device, the silicon oxide layer can be completely removed, the electrical property of the semiconductor device is prevented from being influenced, and the yield of the semiconductor device is prevented from being reduced.
Drawings
FIG. 1 is a flow chart of a method for removing silicon oxide in accordance with one embodiment of the present invention.
Detailed Description
To make the objects, advantages and features of the present invention more apparent, the method for removing silicon oxide and the method for manufacturing a semiconductor device according to the present invention will be described in further detail with reference to fig. 1. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention.
An embodiment of the present invention provides a method for removing silicon oxide, and referring to fig. 1, fig. 1 is a flowchart of a method for removing silicon oxide according to an embodiment of the present invention, the method for removing silicon oxide including the steps of:
step S1, providing a wafer, wherein the surface of the wafer is provided with a silicon oxide layer to be removed;
step S2, soaking the wafer in a first etching solution to remove most of the silicon oxide layer;
and step S3, taking the wafer out of the first etching solution and placing the wafer in a rotating state, and flushing the surface of the wafer by using a second etching solution to remove the residual silicon oxide layer.
The method for removing silicon oxide provided in this embodiment is described in more detail below.
According to step S1, a wafer having a silicon oxide layer on a surface thereof to be removed is provided. The wafer may include a substrate and a film structure formed on the substrate. The substrate may be any suitable substrate known to those skilled in the art, and may be, for example, at least one of the following materials: silicon (Si), germanium (Ge), silicon germanium (SiGe), silicon carbon (SiC), silicon germanium carbon (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs), indium phosphide (InP), or other III/V compound semiconductors, and further includes a multilayer structure composed of these semiconductors, or may be Silicon On Insulator (SOI), silicon on insulator (SSOI), silicon germanium on insulator (S-SiGeOI), silicon germanium on insulator (SiGeOI), and germanium on insulator (GeOI), or may be Double-Side Polished silicon Wafers (DSP), or may be a ceramic substrate such as alumina, quartz, or a glass substrate. The film layer structure formed on the wafer is, for example, a gate structure or a dielectric layer, and the gate structure may be a polysilicon gate or a metal gate. In the present invention, the structure of the wafer is not limited, and an appropriate wafer may be selected according to a device to be formed.
The silicon oxide layer plays an auxiliary role in the manufacturing process of the semiconductor device, and needs to be removed after the semiconductor structure is manufactured, so that the electrical property of the semiconductor device is prevented from being influenced, and the yield of products is prevented from being reduced.
According to step S2, the wafer is immersed in a first etching solution to remove most of the silicon oxide layer. Batches of the wafers can be soaked in the first etching solution, so that the production efficiency is improved.
The first etching liquid may be an acidic solution, and the acidic solution may include a hydrofluoric acid solution. And when the hydrofluoric acid solution is used for removing the silicon oxide layer by soaking, the silicon oxide layer can react with HF in the hydrofluoric acid solution to generate a byproduct, namely fluosilicic acid. Meanwhile, due to the soaking of the hydrofluoric acid solution, silicon at the outermost layer of the surface of the wafer almost takes a hydrogen bond as a terminal structure, so that the surface of the wafer is hydrophobic and has strong activity and instability, and the generated by-products are easily adhered to the surface of the wafer; and when the hydrofluoric acid solution is soaked, the wafer and the hydrofluoric acid solution are almost in a static state, so that byproducts are more easily attached to the surface of the wafer. If the by-products are not removed, the electrical properties of the wafer are also affected, thereby reducing the yield of the product.
The concentration of the hydrofluoric acid solution can be HF and H2The volume ratio of O is 1: 100-1: 20 (for example, 1:80, 1:50, etc.), and the temperature of the hydrofluoric acid solution can be 20-25 ℃. In addition, the concentration of the hydrofluoric acid solution is not limited to the above concentration range, and the volume ratio of HF may be smaller or larger, and an appropriate concentration may be selected according to production needs. The smaller the volume ratio of the HF in the hydrofluoric acid solution is, the longer the wafer needs to be soaked in the hydrofluoric acid solution, so that the more the silicon oxide layer is removed, but the longer the soaking time is, the more by-products are generated by the reaction of the silicon oxide layer and the HF; the larger the volume ratio of HF in the hydrofluoric acid solution is, the more by-products are generated by the reaction of the silicon oxide layer and HF, and therefore, it is necessary to select the hydrofluoric acid solution at a suitable concentration.
The silicon oxide layer with most thickness can be removed by soaking in the hydrofluoric acid solution, for example, when the thickness of the silicon oxide layer isIn this case, the thickness of the silicon oxide layer removed by the hydrofluoric acid solution immersion may be at leastThe residual thickness of the silicon oxide layer can be removed in other subsequent process steps to avoid the problem that the silicon oxide layer is soaked in the hydrofluoric acid solution for too long time to cause the silicon oxide layer to be soaked in the hydrofluoric acid solutionThe amount of by-products adhering to the surface of the wafer increases.
Further, when a batch of the wafers is immersed in the hydrofluoric acid solution in order to improve production efficiency, the silicon oxide layer reacts with HF to generate more by-products, and the concentration of the by-products in the hydrofluoric acid solution increases, resulting in more by-products adhering to the surface of the wafer.
In addition, when the wafer is soaked in the first etching solution, ultrasonic vibration can be accompanied to enhance the force of soaking, etching and removing the silicon oxide layer, so that particles of the silicon oxide layer are easier to separate from the surface of the wafer.
After the wafer is taken out of the first etching solution and before the wafer is rinsed with the second etching solution, the surface of the wafer may be subjected to hydrophilic treatment to remove by-products that are back-adhered to the surface of the wafer. The step of hydrophilizing the surface of the wafer may include: cleaning the surface of the wafer by using SC1 solution, SC2 solution or SC1 solution and SC2 solution in sequence to perform hydrophilic treatment on the surface of the wafer, wherein the SC1 solution is NH4OH、H2O2Mixed solution of H2O and the SC2 solution is HCl and H2O2And H2And (3) a mixed solution of O. The temperature of the SC1 solution can be 30-80 ℃, and NH in the SC1 solution4OH、H2O2And H2The volume ratio of O can be 1:2: 100-1: 2:40 (for example, 1:2:80, 1:2:50, etc.); the temperature of the SC2 solution can be 65-85 ℃, and HCl and H in the SC2 solution2O2And H2The volume ratio of O may be 1:2:100 to 1:2:40 (e.g., 1:2:80, 1:2:50, etc.).
During the process of cleaning the surface of the wafer by using the SC1 solution, the SC1 solution enables the surface of the wafer to continuously keep hydrophilic, so that byproducts adhered back to the surface of the wafer can be removed. In particular, due to H2O2The surface of the wafer forms a layer of hydrophilic materialAqueous natural oxide film (SiO)2) So that the surface of the wafer and the byproducts can be soaked by the SC1 solution; and, the natural oxide film of the surface of the wafer and the silicon of the surface of the wafer are NH4OH corrosion, so that the byproducts adhered to the surface of the wafer fall into an SC1 solution, thereby achieving the purpose of removing the byproducts; and, in NH4OH etching the surface of the wafer while H2O2And forming a new hydrophilic natural oxide film on the surface of the wafer, so that the surface of the wafer is continuously kept hydrophilic.
In the process of cleaning the surface of the wafer by using the SC2 solution, since the SC2 solution is an acidic solution with strong oxidizing property, a hydrophilic natural oxide film is formed on the surface of the wafer, so that the surface of the wafer and the byproducts can be soaked by the SC2 solution, and the byproducts can be cleaned and removed.
In addition, the SC1 solution can also remove other impurity particles on the surface of the wafer, and the SC2 solution can also remove metal contamination of sodium, iron, magnesium and the like on the surface of the wafer.
According to step S3, the wafer is taken out of the first etching solution and then placed in a rotating state, and the surface of the wafer is rinsed with a second etching solution to remove the remaining silicon oxide layer. The second etching solution may also be an acidic solution, and the second etching solution may be an acidic solution having the same composition and concentration as the first etching solution, that is, the second etching solution may also include a hydrofluoric acid solution. The concentration of the hydrofluoric acid solution is referred to the step S2, and is not described in detail herein.
The rinsing with the hydrofluoric acid solution of the second etching solution also causes a problem of by-product sticking back to the surface of the wafer. However, the remaining silicon oxide layer is removed by rinsing, and the wafer is rotated, so that most of the generated by-products are carried away from the surface of the wafer by the rinsing and the centrifugal force of rotation. Therefore, the amount of the by-products sticking back on the surface of the wafer caused by rinsing the surface of the wafer with the hydrofluoric acid solution of the second etching liquid is much less than the amount of the by-products sticking back on the surface of the wafer caused by soaking the wafer with the hydrofluoric acid solution of the first etching liquid.
In order to avoid excessive by-products attached to the surface of the wafer due to the excessively long soaking time in the hydrofluoric acid solution of the first etching solution and to enable the silicon oxide layer remaining on the surface of the wafer to be completely removed by the hydrofluoric acid solution of the second etching solution, the thickness of the silicon oxide layer removed by the hydrofluoric acid solution of the second etching solution can be controlled not to exceed the thickness of the silicon oxide layer removed by the hydrofluoric acid solution of the second etching solution
In addition, the hydrofluoric acid solution of the second etching solution can also remove the natural oxide film generated when the SC1 solution and the SC2 solution in the step S2 perform the hydrophilic treatment on the surface of the wafer, and can suppress the formation of a new natural oxide film.
In addition, after the step S2, the surface of the wafer may not be subjected to the hydrophilic treatment, and the hydrophilic treatment may be performed on the surface of the wafer directly after the rinsing with the second etching solution in the step S3, so as to remove the by-product re-adhered to the surface of the wafer in the step S2 and the by-product re-adhered to the surface of the wafer in the step S3 together. Alternatively, the surface of the wafer may be subjected to hydrophilic treatment after the wafer is taken out from the first etching solution in step S2 and after the wafer is rinsed with the second etching solution in step S3, so as to avoid the problems of slow removal speed and incomplete removal due to excessive accumulation of by-products.
The step of performing hydrophilic treatment on the surface of the wafer after rinsing with the second etching solution may also include: using SC1 solution or SC2 solution or the likeCleaning the surface of the wafer with a SC1 solution and a SC2 solution to remove byproducts that are adhered back on the surface of the wafer. Wherein the SC1 solution is NH4OH、H2O2And H2O, the SC2 solution is HCl and H2O2And H2And (3) a mixed solution of O. The concentrations of the SC1 solution and the SC2 solution and the principle of removing byproducts are referred to the above step S2, and are not described herein again.
In addition, the wafer is placed in a rotating state, and the surface of the wafer is washed, so that the silicon oxide layer and the byproducts at each position of the surface of the wafer can be cleaned, and under the action of the rotating centrifugal force, particles of the silicon oxide layer and particles of the byproducts are more easily separated from the surface of the wafer and fall out, and further the silicon oxide layer and the byproducts can be completely removed.
In addition, the steps in the method for removing silicon oxide are not limited to the formation sequence, and the sequence of the steps can be adjusted adaptively.
In summary, the method for removing silicon oxide provided by the present invention includes: providing a wafer, wherein the surface of the wafer is provided with a silicon oxide layer to be removed; soaking the wafer in a first etching solution to remove most of the silicon oxide layer; and taking the wafer out of the first etching solution, placing the wafer in a rotating state, and flushing the surface of the wafer by adopting a second etching solution to remove the residual silicon oxide layer. The method for removing the silicon oxide provided by the invention can completely remove the silicon oxide layer, and avoids influencing the electrical property of the product, thereby avoiding reducing the yield of the product.
An embodiment of the present invention provides a method for manufacturing a semiconductor device, including: by using the method for removing silicon oxide provided by the present invention (i.e., the steps S1 to S3), a silicon oxide layer on a wafer surface is removed. The wafer includes a core region and a peripheral region, a top surface of the core region being higher than a top surface of the peripheral region. In order to avoid damage to the core region during subsequent semiconductor device fabrication processes (e.g., chemical mechanical polishing the semiconductor device may damage the tall core region), a thickness of silicon oxide may be deposited on the peripheral region to balance the height difference between the core region and the peripheral region. The silicon oxide layer serves to assist in the manufacture of the semiconductor structure during the manufacture of the semiconductor device and needs to be removed after the manufacture of the semiconductor structure is completed.
And forming the silicon oxide layer on the wafer, and carrying out chemical mechanical polishing on the wafer to expose the top surface of the core area and make the top surface of the core area flush with the top surface of the silicon oxide layer on the peripheral area.
Specifically, the silicon oxide layer may be formed on the peripheral region such that the top surface of the core region is lower than or flush with the top surface of the silicon oxide layer. When the top surface of the core area is lower than the top surface of the silicon oxide layer, before the wafer is soaked in the first etching solution, the silicon oxide layer on the peripheral area is thinned by adopting a chemical mechanical polishing process, so that the top surface of the core area is flush with the top surface of the silicon oxide layer on the peripheral area. On the other hand, the silicon oxide layer may be formed on both the peripheral region and the core region, and before the wafer is immersed in the first etching solution, the silicon oxide layer on the core region and the peripheral region is thinned by using a chemical mechanical polishing process until the top surface of the core region is exposed, and a layer below the silicon oxide layer of the core region may be a film structure of the core region.
In this embodiment, the semiconductor device may include a memory array, and the core region is a memory region in which the memory array is located. After the process step of fabricating the film structure is performed on the core region and/or the peripheral region, the silicon oxide layer on the surface of the wafer is removed by the method of the above steps S1 to S3, so that the silicon oxide layer can be completely removed, and the electrical performance of the semiconductor device is prevented from being affected, thereby preventing the yield of the semiconductor device from being reduced.
The above description is only for the purpose of describing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art based on the above disclosure are within the scope of the appended claims.
Claims (12)
1. A method of removing silicon oxide, comprising:
providing a wafer, wherein the surface of the wafer is provided with a silicon oxide layer to be removed;
soaking the wafer in a first etching solution to remove most of the silicon oxide layer;
and taking the wafer out of the first etching solution, placing the wafer in a rotating state, and flushing the surface of the wafer by adopting a second etching solution to remove the residual silicon oxide layer.
2. The method for removing silicon oxide according to claim 1, wherein the first etching liquid and the second etching liquid are both acidic solutions.
3. The method for removing silicon oxide according to claim 2, wherein the first etching liquid and the second etching liquid are acidic solutions having the same composition and concentration.
4. The method for removing silicon oxide according to claim 2 or 3, wherein the acidic solution comprises a hydrofluoric acid solution in which HF and H are contained2The volume ratio of O is 1: 100-1: 20.
5. The method for removing silicon oxide according to claim 1, wherein the wafer is immersed in the first etching solution accompanied by ultrasonic vibration.
6. The method for removing silicon oxide according to claim 1, wherein the surface of the wafer is subjected to hydrophilic treatment after the wafer is taken out of the first etching solution and before rinsing with the second etching solution, and/or after rinsing with the second etching solution, to remove by-products that are back-adhered to the surface of the wafer.
7. The method of claim 6, wherein the surface of the wafer is subjected to a hydrophilic treatment by cleaning the surface of the wafer with a solution SC1, a solution SC2, a solution SC1 and a solution SC2 in sequence, wherein the solution SC1 is NH4OH、H2O2And H2O, the SC2 solution is HCl and H2O2And H2And (3) a mixed solution of O.
8. The method for removing silicon oxide according to claim 7, wherein NH in the SC1 solution4OH、H2O2And H2The volume ratio of O is 1:2: 100-1: 2: 40; HCl and H in the SC2 solution2O2And H2The volume ratio of O is 1:2: 100-1: 2: 40.
9. A method of manufacturing a semiconductor device, comprising: removing the silicon oxide layer on the surface of a wafer by using the method for removing silicon oxide according to any one of claims 1 to 8.
10. The method of manufacturing a semiconductor device according to claim 9, wherein the wafer comprises a core region and a peripheral region, a top surface of the core region being higher than a top surface of the peripheral region.
11. The method of claim 10, wherein the silicon oxide layer is formed on the wafer, and the wafer is subjected to chemical mechanical polishing to expose a top surface of the core region, the top surface of the core region being flush with a top surface of the silicon oxide layer on the peripheral region.
12. The method for manufacturing a semiconductor device according to claim 10 or 11, wherein the semiconductor device includes a memory array, and the core region is a memory region in which the memory array is located.
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