CN116825611A - Polishing method of semiconductor substrate - Google Patents
Polishing method of semiconductor substrate Download PDFInfo
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- CN116825611A CN116825611A CN202310901082.6A CN202310901082A CN116825611A CN 116825611 A CN116825611 A CN 116825611A CN 202310901082 A CN202310901082 A CN 202310901082A CN 116825611 A CN116825611 A CN 116825611A
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- 239000004065 semiconductor Substances 0.000 title claims abstract description 199
- 239000000758 substrate Substances 0.000 title claims abstract description 197
- 238000005498 polishing Methods 0.000 title claims abstract description 184
- 238000000034 method Methods 0.000 title claims abstract description 51
- 239000007788 liquid Substances 0.000 claims abstract description 83
- 239000012752 auxiliary agent Substances 0.000 claims abstract description 29
- 239000003513 alkali Substances 0.000 claims abstract description 28
- 238000005406 washing Methods 0.000 claims abstract description 18
- 239000008367 deionised water Substances 0.000 claims abstract description 14
- 229910021641 deionized water Inorganic materials 0.000 claims abstract description 14
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 14
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 18
- 238000004140 cleaning Methods 0.000 claims description 16
- 238000007517 polishing process Methods 0.000 claims description 11
- 238000007602 hot air drying Methods 0.000 claims description 10
- 239000002518 antifoaming agent Substances 0.000 claims description 7
- WXMKPNITSTVMEF-UHFFFAOYSA-M sodium benzoate Chemical compound [Na+].[O-]C(=O)C1=CC=CC=C1 WXMKPNITSTVMEF-UHFFFAOYSA-M 0.000 claims description 7
- 235000010234 sodium benzoate Nutrition 0.000 claims description 7
- 239000004299 sodium benzoate Substances 0.000 claims description 7
- 239000004094 surface-active agent Substances 0.000 claims description 7
- 230000008569 process Effects 0.000 abstract description 24
- 230000007797 corrosion Effects 0.000 abstract description 4
- 238000005260 corrosion Methods 0.000 abstract description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 15
- 239000007789 gas Substances 0.000 description 15
- 229910052710 silicon Inorganic materials 0.000 description 15
- 239000010703 silicon Substances 0.000 description 15
- 229910052751 metal Inorganic materials 0.000 description 12
- 239000002184 metal Substances 0.000 description 12
- 239000000243 solution Substances 0.000 description 10
- 230000000694 effects Effects 0.000 description 5
- 230000002708 enhancing effect Effects 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 238000002679 ablation Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 239000000843 powder Substances 0.000 description 4
- 241001391944 Commicarpus scandens Species 0.000 description 3
- 238000005530 etching Methods 0.000 description 3
- 150000002739 metals Chemical class 0.000 description 3
- 230000009471 action Effects 0.000 description 2
- 239000012459 cleaning agent Substances 0.000 description 2
- 230000003749 cleanliness Effects 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 229910003460 diamond Inorganic materials 0.000 description 2
- 239000010432 diamond Substances 0.000 description 2
- 239000011259 mixed solution Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 229910021421 monocrystalline silicon Inorganic materials 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 244000137852 Petrea volubilis Species 0.000 description 1
- 229910000577 Silicon-germanium Inorganic materials 0.000 description 1
- LEVVHYCKPQWKOP-UHFFFAOYSA-N [Si].[Ge] Chemical compound [Si].[Ge] LEVVHYCKPQWKOP-UHFFFAOYSA-N 0.000 description 1
- 239000003518 caustics Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 238000005247 gettering Methods 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 230000008595 infiltration Effects 0.000 description 1
- 238000001764 infiltration Methods 0.000 description 1
- IJGRMHOSHXDMSA-UHFFFAOYSA-N nitrogen Substances N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 210000003437 trachea Anatomy 0.000 description 1
- 239000013585 weight reducing agent Substances 0.000 description 1
Classifications
-
- 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
-
- 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
- H01L21/02019—Chemical etching
-
- 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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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Manufacturing & Machinery (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Mechanical Treatment Of Semiconductor (AREA)
Abstract
The invention relates to the technical field of solar cells, and particularly provides a polishing method of a semiconductor substrate, which comprises the following steps: providing a semiconductor substrate; ultrasonic alkaline washing is carried out on the semiconductor substrate; polishing the semiconductor substrate to reduce the line mark degree of the two side surfaces of the semiconductor substrate; the polishing treatment adopts polishing treatment liquid, and the polishing treatment liquid comprises alkali liquor, polishing auxiliary agent and deionized water. The polishing method of the semiconductor substrate can improve the flatness of the surface line marks of the semiconductor substrate, and the damaged layer is removed without additional corrosion treatment before the semiconductor substrate is polished, so that the process cost is low.
Description
Technical Field
The invention relates to the technical field of solar cells, in particular to a polishing method of a semiconductor substrate.
Background
The cost statistics of each production link of the solar cell is that the cost of the silicon wafer is the first cost, which accounts for more than 50% of the total cost. The thickness of the current mainstream silicon wafer is 160-180 mu m, the price of the silicon wafer can be reduced by 10% when the silicon wafer is thinned by 20 mu m, and the price of the corresponding photovoltaic module is reduced by 6-7 minutes/W. The chip rate is affected after the silicon wafer is thinned, so that the texturing weight reduction of the silicon wafer needs to be correspondingly reduced, the line mark on the surface of the silicon wafer is eliminated, the line mark height affects the subsequent process, and a flatter surface is needed for a heterojunction battery. In order to meet the requirements of the silicon wafer surface with low linear mark degree (less than or equal to 3 mu m) after the silicon wafer flaking and the purpose of meeting the silicon wafer surface with the metal content of the gettering surface (less than or equal to 25 ppb), the exploration and development of a novel ultra-precise process technology becomes a critical task for the photovoltaic industry on the silicon wafer surface treatment.
The conventional polishing process for the surface of the semiconductor substrate adopts mechanical polishing, and the mechanical polishing requires polishing processes such as an ultrasonic grinder, sand paper, a polishing cloth wheel, oil-soluble diamond grinding paste and the like to sequentially polish the surface of the semiconductor substrate, so that mechanical damage is easily caused to the surface of the semiconductor substrate.
Etching polishing is a common process method, including alkaline etching polishing. Specifically, the surface etching and polishing treatment is carried out on the semiconductor substrate by using alkali liquor and a groove type device. However, the single alkali solution has small infiltration capacity on the surface of the semiconductor substrate, and the polishing of the semiconductor substrate is carried out by only adopting the alkali solution, so that the flatness of the line mark on the surface of the obtained semiconductor substrate is poor; secondly, before polishing the semiconductor substrate, the damaged layer on the surface of the semiconductor substrate needs to be removed, and the redundant process steps make the process cost high.
Disclosure of Invention
Therefore, the technical problem to be solved by the invention is to overcome the defects of poor flatness of the line mark on the surface of the semiconductor substrate and high process cost in the prior art, thereby providing a polishing method of the semiconductor substrate.
The invention provides a polishing method of a semiconductor substrate, comprising the following steps: providing a semiconductor substrate; performing ultrasonic alkaline washing on the semiconductor substrate; polishing the semiconductor substrate to reduce the line mark degree of the two side surfaces of the semiconductor substrate; the polishing treatment adopts polishing treatment liquid, wherein the polishing treatment liquid comprises alkali liquor, polishing auxiliary agent and deionized water.
Optionally, the mass ratio of the alkali solution, the polishing auxiliary agent and the deionized water in the polishing treatment solution is 1wt% to 3wt%, 0.5wt% to 1.5wt% and 96wt% to 98.5wt%, respectively.
Optionally, the polishing auxiliary comprises sodium benzoate, an antifoaming agent, and a surfactant; wherein, the mass percent of sodium benzoate in the polishing auxiliary agent is 1wt percent to 2wt percent; the mass percentage of the defoaming agent in the polishing auxiliary agent is 3-4wt%; the mass percentage of the surfactant in the polishing auxiliary agent is 7-9 wt%.
Optionally, the alkali liquor in the polishing treatment solution comprises KOH solution, and the mass percentage concentration of the KOH is 1-3 wt%.
Optionally, the polishing treatment is carried out at a temperature of 60-80 ℃; the time is 100s-300s.
Optionally, the ultrasonic alkaline washing is carried out at a frequency of 40kHz-80kHz; the temperature is 50-60 ℃; the time is 150s-300s.
Optionally, the step of polishing the semiconductor substrate includes: providing an accommodating groove and a polishing groove, wherein the polishing groove is provided with a liquid inlet; adding polishing treatment liquid into the accommodating groove, and providing the polishing treatment liquid for the accommodating groove through the liquid inlet; and placing the semiconductor substrate in a polishing groove, and polishing the semiconductor substrate by adopting polishing treatment liquid.
Optionally, an overflow groove is arranged at the outer side part of the polishing groove, the overflow groove is provided with a liquid outlet, and the overflow groove is communicated with the accommodating groove through the liquid outlet; the step of polishing the semiconductor substrate further includes: the overflow of the polishing treatment liquid in the polishing groove is collected by the overflow groove, and the polishing treatment liquid collected by the overflow groove enters the accommodating groove through the liquid outlet to be recycled.
Optionally, the method further comprises: and after ultrasonic alkaline washing is carried out on the semiconductor substrate, hydrogen peroxide washing is carried out on the semiconductor substrate before polishing treatment is carried out on the semiconductor substrate.
Optionally, the temperature for hydrogen peroxide treatment is 50-60 ℃ and the time is 150-300 s.
Optionally, the method further comprises: and after polishing the semiconductor substrate, carrying out ultrasonic rinsing treatment on the semiconductor substrate.
Optionally, the ultrasonic rinsing treatment is carried out by deionized water washing; the frequency of the ultrasonic rinsing treatment is 40kHz-80kHz; the ultrasonic rinsing treatment is carried out for 150s-300s.
Optionally, the method further comprises: after ultrasonic rinsing treatment is carried out on the semiconductor substrate, carrying out hot air drying treatment on the semiconductor substrate; the temperature of the hot air drying treatment is 60-100 ℃; the time of the hot air drying treatment is 200s-500s.
The technical scheme of the invention has the following advantages:
according to the polishing method of the semiconductor substrate, ultrasonic alkaline washing is carried out on the semiconductor substrate, so that powder on the surface of the semiconductor substrate is rapidly dropped off, organic matters and metal residues on the surface of the semiconductor substrate are removed, and line marks on the surface of the semiconductor substrate are exposed; the polishing treatment liquid is used for polishing the semiconductor substrate so as to reduce the line mark degree of the surfaces of the two sides of the semiconductor substrate, and the mechanical damage to the surface of the semiconductor substrate can be avoided due to no mechanical action in the polishing treatment process. The polishing treatment liquid comprises alkali liquor, a polishing auxiliary agent and deionized water, wherein the polishing auxiliary agent is used for enhancing the wettability of the surface of the semiconductor substrate, so that the alkali liquor is convenient to contact with the surface of the semiconductor substrate, particularly the alkali liquor is convenient to contact with a high-line mark area of the surface of the semiconductor substrate, and the ablation ratio of the polishing treatment liquid to the high-line mark area is larger than that of the polishing treatment liquid to a low-line mark area in the polishing treatment process, so that the flatness of the line mark on the surface of the semiconductor substrate is improved; and secondly, in the polishing process, the polishing auxiliary agent is used for enhancing the wettability of the surface of the semiconductor substrate, so that alkali liquor is convenient to contact with the surface of the semiconductor substrate, and part of the damaged layer on the surface of the semiconductor substrate is removed, so that the damaged layer is removed without additional corrosion treatment before the polishing process is carried out on the semiconductor substrate, and the production cost of the process is reduced.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a method for polishing a semiconductor substrate according to an embodiment of the present invention;
FIGS. 2 to 7 are schematic views showing the structure of a polishing method for a semiconductor substrate according to an embodiment of the present invention;
reference numerals illustrate:
1-a semiconductor substrate; 2-line mark.
Detailed Description
The following description of the embodiments of the present invention will be made apparent and fully in view of the accompanying drawings, in which some, but not all embodiments of the invention are shown. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In addition, the technical features of the different embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
An embodiment of the present invention provides a polishing method of a semiconductor substrate, referring to fig. 1, including:
s1: providing a semiconductor substrate;
s2: performing ultrasonic alkaline washing on the semiconductor substrate;
s3: polishing the semiconductor substrate to reduce the line mark degree of the two side surfaces of the semiconductor substrate; the polishing treatment adopts polishing treatment liquid, wherein the polishing treatment liquid comprises alkali liquor, polishing auxiliary agent and deionized water.
In this embodiment, ultrasonic alkaline washing is performed on the semiconductor substrate, so that powder on the surface of the semiconductor substrate is rapidly removed to remove residues of organic matters and metals on the surface of the semiconductor substrate, and lines on the surface of the semiconductor substrate are exposed; the polishing treatment liquid is used for polishing the semiconductor substrate so as to reduce the line mark degree of the surfaces of the two sides of the semiconductor substrate, and the mechanical damage to the surface of the semiconductor substrate can be avoided due to no mechanical action in the polishing treatment process. The polishing treatment liquid comprises alkali liquor, a polishing auxiliary agent and deionized water, wherein the polishing auxiliary agent is used for enhancing the wettability of the surface of the semiconductor substrate, so that the alkali liquor is convenient to contact with the surface of the semiconductor substrate, particularly the alkali liquor is convenient to contact with a high-line mark area of the surface of the semiconductor substrate, and the ablation ratio of the polishing treatment liquid to the high-line mark area is larger than that of the polishing treatment liquid to a low-line mark area in the polishing treatment process, so that the flatness of the line mark on the surface of the semiconductor substrate is improved; and secondly, in the polishing process, the polishing auxiliary agent is used for enhancing the wettability of the surface of the semiconductor substrate, so that alkali liquor is convenient to contact with the surface of the semiconductor substrate, and part of the damaged layer on the surface of the semiconductor substrate is removed, so that the damaged layer is removed without additional corrosion treatment before the polishing process is carried out on the semiconductor substrate, and the production cost of the process is reduced.
The polishing method of the semiconductor substrate will be described in detail with reference to fig. 2 to 7.
Referring to fig. 2, a semiconductor substrate 1 is provided.
The material of the semiconductor substrate 1 comprises silicon. In other embodiments, the material of the semiconductor substrate is other semiconductor materials, such as single crystal silicon or silicon germanium. The material of the semiconductor substrate can also be other semiconductor materials.
In this embodiment, the two side surfaces of the semiconductor substrate 1 have a plurality of uneven lines 2. In a specific embodiment, the front surface and the back surface of the semiconductor substrate 1 are provided with a plurality of uneven lines 2.
The line mark 2 is a linear groove having uneven height remaining on the surface of the semiconductor substrate 1 when the semiconductor substrate 1 is cut by a diamond wire.
In this embodiment, the semiconductor substrate 1 has damage layers (not shown) on both side surfaces. Specifically, the front surface and the back surface of the semiconductor substrate 1 are provided with damaged layers. The damaged layer is caused during the process of cutting the silicon rod raw material to form the semiconductor substrate. Is always present before the subsequent polishing treatment.
Referring to fig. 3, the semiconductor substrate 1 is subjected to ultrasonic alkali washing.
The ultrasonic alkaline washing is performed on the semiconductor substrate 1, so that powder on the surface of the semiconductor substrate 1 is rapidly separated in a vibration mode, and residues of organic matters and metals on the surface of the semiconductor substrate 1 are removed.
Specifically, the ultrasonic alkaline cleaning may be performed not only to clean the front surface of the semiconductor substrate 1 but also to clean the back surface of the semiconductor substrate 1. In this embodiment, ultrasonic alkaline cleaning is performed simultaneously on the front surface and the back surface of the semiconductor substrate 1.
In one embodiment, ultrasonic alkaline cleaning is performed by using a mixed solution of cleaning liquid A and cleaning liquid B, wherein the model of the cleaning liquid A is DY-120A cleaning agent, and the model of the cleaning liquid B is DY-120B cleaning agent.
In one embodiment, the ultrasonic alkaline wash is performed at a frequency of 40kHz-80kHz, such as 40kHz, 50kHz, 60kHz, 70kHz, or 80kHz. If the frequency of ultrasonic alkaline washing is too high, the semiconductor substrate is easy to break, and the required process cost of the semiconductor substrate is high; if the frequency of the ultrasonic alkaline washing is too low, the powder on the surface of the semiconductor substrate is removed for a long time, and the effect of removing the organic matters and the metal residues on the surface of the semiconductor substrate 1 is weak.
In one embodiment, the ultrasonic caustic wash is performed at a temperature of 50 ℃ to 60 ℃, such as 50 ℃, 55 ℃, or 60 ℃; the time is 150s-300s, for example 150s, 200s, 250s or 300s.
Referring to fig. 4, the semiconductor substrate 1 is subjected to hydrogen peroxide cleaning.
After ultrasonic alkaline cleaning is carried out on the semiconductor substrate 1, hydrogen peroxide cleaning is carried out on the semiconductor substrate 1. The purpose of hydrogen peroxide cleaning is: and oxidizing the organic component on the surface of the semiconductor substrate 1 by using a mixed solution of the cleaning liquid A and the cleaning liquid B used for ultrasonic alkaline cleaning.
In one embodiment, the hydrogen peroxide treatment is performed at a temperature of 50 ℃ to 60 ℃, such as 50 ℃, 55 ℃, or 60 ℃; the time is 150s-300s, for example 150s, 200s, 250s or 300s.
Referring to fig. 5, the semiconductor substrate 1 is subjected to polishing treatment.
After hydrogen peroxide cleaning is performed on the semiconductor substrate 1, polishing treatment is performed on the semiconductor substrate 1 to reduce the line mark degree of the two side surfaces of the semiconductor substrate 1. The test shows that before the polishing treatment is carried out on the semiconductor substrate 1, the line mark degree of the two side surfaces of the semiconductor substrate 1 is less than or equal to 13 mu m; after the semiconductor substrate 1 is polished, the line mark degree of the two side surfaces of the semiconductor substrate 1 is less than or equal to 3 mu m (less than or equal to 3 mu m), and the requirement of low line mark degree after the silicon wafer flaking is completely met.
In this embodiment, the polishing treatment employs a polishing treatment liquid including an alkali solution, a polishing auxiliary agent, and deionized water, the alkali solution, the polishing auxiliary agent, and the deionized water being present in the polishing treatment liquid in a mass ratio of 1wt% to 3wt%, 0.5wt% to 1.5wt%, and 96wt% to 98.5wt%, respectively. The polishing auxiliary agent is used for enhancing the wettability of the surface of the semiconductor substrate 1, so that alkali liquor can be contacted with the surface of the semiconductor substrate 1 conveniently, particularly, alkali liquor can be contacted with a high-mark area on the surface of the semiconductor substrate 1, and the ablation ratio of polishing treatment liquid to the high-mark area is larger than that of polishing treatment liquid to a low-mark area in the polishing treatment process, so that the flatness of the mark on the surface of the semiconductor substrate is improved.
In one embodiment, the alkali liquid in the polishing treatment liquid comprises KOH solution, and the mass percentage concentration of the KOH is 1-3 wt%. Illustratively, the KOH is present at a concentration of 1wt%, 2wt%, or 3wt%. If the mass percentage concentration of the KOH is too large, the semiconductor substrate 1 after polishing treatment is too thin, and the semiconductor substrate 1 is easy to break; if the mass percentage concentration of KOH is too small, the contact effect of alkali liquor and a high-line mark area on the surface of the semiconductor substrate 1 is smaller, and the effect of improving the flatness of the line mark on the surface of the semiconductor substrate is weaker.
In one embodiment, the polishing aid includes sodium benzoate, an antifoaming agent, and a surfactant. Wherein, the mass percent of sodium benzoate in the polishing auxiliary agent is 1wt percent to 2wt percent; the mass percentage of the defoaming agent in the polishing auxiliary agent is 3-4wt%; the mass percentage of the surfactant in the polishing auxiliary agent is 7-9 wt%. Illustratively, the polishing aid comprises 1wt%, 1.5wt%, or 2wt% sodium benzoate; the mass percentage of the defoaming agent in the polishing auxiliary agent is 3wt%, 3.5wt% or 4wt%; the mass percentage of the surfactant in the polishing auxiliary agent is 7wt%, 8wt% or 9wt%.
In one embodiment, the polishing process is performed at a temperature of 60 ℃ to 80 ℃, such as 60 ℃, 70 ℃, or 80 ℃; the time is 100s-300s, for example 100s, 200s or 300s.
In this embodiment, the step of polishing the semiconductor substrate includes: providing a containing groove and a polishing groove, wherein the bottom wall of the polishing groove is provided with a liquid inlet and an air pipe, and the air pipe is communicated with an external air source for releasing air into the polishing groove; the accommodating groove is communicated with the liquid inlet through a first liquid pipe; providing a basket, placing the semiconductor substrate in the basket, and placing the basket in the polishing groove; and adding polishing treatment liquid into the accommodating groove, providing the polishing treatment liquid for the accommodating groove through the liquid inlet, and polishing the semiconductor substrate by adopting the polishing treatment liquid. In the process that the holding tank provides the polishing treatment liquid to the polishing tank through the liquid inlet, the air pipe releases gas to the polishing tank, and continuous bubbles are formed in the polishing treatment liquid, so that the mobility of the polishing treatment liquid can be increased, and uniform polishing treatment liquid can be formed, thereby improving the effect of polishing treatment on the semiconductor substrate.
In one embodiment, the sidewall of the trachea has a plurality of small holes. The gas entering the gas pipe releases the gas into the polishing groove through the small holes, so that the defect that the polishing treatment liquid is in contact with the semiconductor substrate to a small extent due to overlarge bubbles generated in the polishing groove is avoided.
In this embodiment, the gas in the gas pipe is nitrogen. In other embodiments, the gas of the gas tube is other inert gas.
In one embodiment, a flow homogenizing plate is arranged inside the polishing groove, and the flow homogenizing plate is positioned between the semiconductor substrate and the air pipe; the step of polishing the semiconductor substrate further includes: the gas released by the gas pipe passes through the uniform flow plate to flush the surface of the semiconductor substrate. The gas released by the gas pipe passes through the uniform flow plate, so that the uniformity of the gas can be improved, and the gas released by the gas pipe can take away bubbles generated on the surface of the semiconductor substrate, so that the contact between the polishing treatment liquid and the surface of the semiconductor substrate is facilitated, and the polishing effect on the surface of the semiconductor substrate is improved.
In one embodiment, an overflow groove is arranged at the outer side part of the polishing groove, and the bottom surface of the overflow groove is connected with the outer side wall of the polishing groove; the overflow groove is provided with a liquid outlet, and the overflow groove is communicated with the containing groove through the liquid outlet.
The step of polishing the semiconductor substrate further includes: the overflow of the polishing treatment liquid in the polishing groove is collected by the overflow groove, and the polishing treatment liquid collected by the overflow groove enters the accommodating groove through the liquid outlet to be recycled.
Specifically, the polishing treatment liquid in the holding tank is pumped to the polishing tank through the first liquid pipe by the pump, and overflows to the overflow tank after the polishing treatment liquid in the polishing tank is full, the holding tank is communicated with the liquid outlet through the second liquid pipe, and the polishing treatment liquid in the overflow tank flows to the holding tank through the liquid outlet to form the circulation of the polishing treatment liquid.
In this embodiment, during the polishing process of the semiconductor substrate, a part of the damaged layer on the surface of the semiconductor substrate 1 is removed, and at the same time, a part of metals such as Fe, ni, etc. remaining during the process of cutting the single crystal silicon raw material to form the semiconductor substrate is removed, so that the metal content on the surface of the obtained semiconductor substrate is low. The metal content of the surface of the semiconductor substrate 1 is less than or equal to 54ppb before the semiconductor substrate 1 is polished; after the semiconductor substrate 1 is subjected to polishing treatment, the metal content of the surface of the semiconductor substrate 1 is less than or equal to 25ppb (25 ppb or less). Meanwhile, before the semiconductor substrate is polished, no additional corrosion treatment is needed on the surface of the semiconductor substrate, so that the production cost of the process can be reduced, and the processing efficiency of the semiconductor substrate is high.
Referring to fig. 6, the semiconductor substrate 1 is subjected to ultrasonic rinsing treatment.
After the semiconductor substrate 1 is subjected to the polishing process, the semiconductor substrate 1 is subjected to the ultrasonic rinsing process. Bubbles are generated by ultrasonic vibration to carry away residual polishing treatment liquid and dirt substances on the surface of the semiconductor substrate 1, so that the surface cleanliness of the semiconductor substrate 1 is improved.
In one embodiment, the performing ultrasonic rinsing treatment employs deionized water washing; the ultrasonic rinsing treatment is carried out at a frequency of 40kHz to 80kHz, for example, 40kHz, 50kHz, 60kHz, 70kHz or 80kHz. If the frequency of ultrasonic rinsing treatment is too high, the semiconductor substrate is easy to break, and the process cost of the required semiconductor substrate is high; if the frequency of the ultrasonic rinsing treatment is too small, the ability to improve the surface cleanliness of the semiconductor substrate is weak.
In one embodiment, the time for performing the ultrasonic rinsing process is 150s to 300s, for example 150s, 200s, 250s or 300s.
In this example, the ultrasonic rinsing treatment was performed at room temperature.
Referring to fig. 7, the semiconductor substrate 1 is subjected to a hot air drying process.
After the ultrasonic rinsing treatment is performed on the semiconductor substrate 1, the semiconductor substrate 1 is subjected to a hot air drying treatment.
In one embodiment, the temperature of the hot air drying process is from 60 ℃ to 100 ℃, such as 60 ℃, 70 ℃, 80 ℃, 90 ℃, or 100 ℃; the hot air drying treatment time is 200s-500s, for example 200s, 300s, 400s or 500s.
The polishing method of the semiconductor substrate provided by the embodiment is safe and reliable, has high flexibility, high controllability and good repeatability, can be used for processing the semiconductor substrate with a large area, and is easy to realize industrial application. The polishing treatment liquid comprises alkali liquor, polishing auxiliary agent and deionized water, so that the wettability of the polishing auxiliary agent on the surface of the semiconductor substrate is enhanced, and particularly, the contact between the alkali liquor and a high-mark area on the surface of the semiconductor substrate is facilitated, so that the ablation ratio of the polishing treatment liquid and the high-mark area is larger than that of the polishing treatment liquid and the low-mark area in the polishing treatment process, and the flatness of the mark on the surface of the semiconductor substrate is improved. Therefore, the polishing treatment liquid is used for polishing the semiconductor substrate, so that the line mark degree of the two side surfaces of the semiconductor substrate can be reduced. Through testing, before the semiconductor substrate is polished, the line mark degree of the two side surfaces of the semiconductor substrate is less than or equal to 13 mu m; after the semiconductor substrate 1 is polished, the line mark degree of the two side surfaces of the semiconductor substrate 1 is less than or equal to 3 mu m (less than or equal to 3 mu m), and the requirement of low line mark degree after the silicon wafer flaking is completely met.
In addition, in the polishing process of the semiconductor substrate, a part of the damaged layer on the surface of the semiconductor substrate 1 is removed, and the metal content of the surface of the semiconductor substrate is low. The metal content of the surface of the semiconductor substrate 1 is less than or equal to 54ppb before the semiconductor substrate 1 is polished; after the semiconductor substrate 1 is subjected to polishing treatment, the metal content of the surface of the semiconductor substrate 1 is less than or equal to 25ppb (25 ppb or less).
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. While still being apparent from variations or modifications that may be made by those skilled in the art are within the scope of the invention.
Claims (10)
1. A method of polishing a semiconductor substrate, comprising:
providing a semiconductor substrate;
performing ultrasonic alkaline washing on the semiconductor substrate;
polishing the semiconductor substrate to reduce the line mark degree of the two side surfaces of the semiconductor substrate; the polishing treatment adopts polishing treatment liquid, wherein the polishing treatment liquid comprises alkali liquor, polishing auxiliary agent and deionized water.
2. The method for polishing a semiconductor substrate according to claim 1, wherein the mass ratio of the alkali liquid, the polishing auxiliary agent, and the deionized water in the polishing treatment liquid is 1 wt.% to 3 wt.%, 0.5 wt.% to 1.5 wt.%, and 96 wt.% to 98.5 wt.%, respectively.
3. The method for polishing a semiconductor substrate according to claim 1, wherein the polishing auxiliary agent comprises sodium benzoate, an antifoaming agent, and a surfactant;
wherein, the mass percent of sodium benzoate in the polishing auxiliary agent is 1wt percent to 2wt percent;
the mass percentage of the defoaming agent in the polishing auxiliary agent is 3-4wt%;
the mass percentage of the surfactant in the polishing auxiliary agent is 7-9 wt%.
4. The method for polishing a semiconductor substrate according to claim 1, wherein the alkali liquid in the polishing treatment liquid comprises a KOH solution, and the mass percentage concentration of KOH is 1wt% to 3wt%;
preferably, the polishing treatment is carried out at a temperature of 60-80 ℃; the time is 100s-300s.
5. The method for polishing a semiconductor substrate according to any one of claims 1 to 4, wherein the ultrasonic alkaline cleaning is performed at a frequency of 40kHz to 80kHz; the temperature is 50-60 ℃; the time is 150s-300s.
6. The method for polishing a semiconductor substrate according to any one of claims 1 to 4, wherein the step of subjecting the semiconductor substrate to polishing treatment comprises: providing an accommodating groove and a polishing groove, wherein the polishing groove is provided with a liquid inlet; adding polishing treatment liquid into the accommodating groove, and providing the polishing treatment liquid for the accommodating groove through the liquid inlet; and placing the semiconductor substrate in a polishing groove, and polishing the semiconductor substrate by adopting polishing treatment liquid.
7. The method for polishing a semiconductor substrate according to claim 6, wherein an outer side portion of the polishing bath is provided with an overflow bath having a liquid outlet through which the overflow bath communicates with the accommodating bath;
the step of polishing the semiconductor substrate further includes: the overflow of the polishing treatment liquid in the polishing groove is collected by the overflow groove, and the polishing treatment liquid collected by the overflow groove enters the accommodating groove through the liquid outlet to be recycled.
8. The method for polishing a semiconductor substrate according to any one of claims 1 to 4, further comprising: after ultrasonic alkaline washing is carried out on the semiconductor substrate, hydrogen peroxide washing is carried out on the semiconductor substrate before polishing treatment is carried out on the semiconductor substrate;
preferably, the temperature of the hydrogen peroxide treatment is 50-60 ℃ and the time is 150-300 s.
9. The method for polishing a semiconductor substrate according to any one of claims 1 to 4, further comprising: after polishing the semiconductor substrate, carrying out ultrasonic rinsing treatment on the semiconductor substrate;
preferably, the ultrasonic rinsing treatment is carried out by adopting deionized water for washing; the frequency of the ultrasonic rinsing treatment is 40kHz-80kHz; the ultrasonic rinsing treatment is carried out for 150s-300s.
10. The method for polishing a semiconductor substrate according to claim 9, further comprising: after ultrasonic rinsing treatment is carried out on the semiconductor substrate, carrying out hot air drying treatment on the semiconductor substrate; the temperature of the hot air drying treatment is 60-100 ℃; the time of the hot air drying treatment is 200s-500s.
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