CN112390259B - Electronic grade polysilicon cleaning method - Google Patents
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- CN112390259B CN112390259B CN202011290207.9A CN202011290207A CN112390259B CN 112390259 B CN112390259 B CN 112390259B CN 202011290207 A CN202011290207 A CN 202011290207A CN 112390259 B CN112390259 B CN 112390259B
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- 238000004140 cleaning Methods 0.000 title claims abstract description 232
- 238000000034 method Methods 0.000 title claims abstract description 69
- 229910021420 polycrystalline silicon Inorganic materials 0.000 title claims abstract description 27
- 229920005591 polysilicon Polymers 0.000 title claims abstract description 23
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 147
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 147
- 239000010703 silicon Substances 0.000 claims abstract description 147
- 239000007788 liquid Substances 0.000 claims abstract description 41
- 229910017604 nitric acid Inorganic materials 0.000 claims abstract description 21
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 21
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims abstract description 12
- 239000000203 mixture Substances 0.000 claims abstract description 5
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims abstract description 3
- 239000004484 Briquette Substances 0.000 claims description 53
- 238000011282 treatment Methods 0.000 claims description 46
- 230000008569 process Effects 0.000 claims description 35
- 230000000694 effects Effects 0.000 abstract description 10
- 238000011143 downstream manufacturing Methods 0.000 abstract description 3
- 239000000243 solution Substances 0.000 description 77
- 230000007797 corrosion Effects 0.000 description 19
- 238000005260 corrosion Methods 0.000 description 19
- 238000005530 etching Methods 0.000 description 14
- 239000002253 acid Substances 0.000 description 11
- 239000012535 impurity Substances 0.000 description 11
- 239000010410 layer Substances 0.000 description 10
- 239000003513 alkali Substances 0.000 description 9
- 238000005406 washing Methods 0.000 description 8
- 238000004519 manufacturing process Methods 0.000 description 7
- 239000013078 crystal Substances 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 4
- 230000002209 hydrophobic effect Effects 0.000 description 3
- 230000005661 hydrophobic surface Effects 0.000 description 3
- 230000007246 mechanism Effects 0.000 description 3
- 239000007853 buffer solution Substances 0.000 description 2
- 230000003749 cleanliness Effects 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000012216 screening Methods 0.000 description 2
- 239000012498 ultrapure water Substances 0.000 description 2
- 230000001154 acute effect Effects 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000003670 easy-to-clean Effects 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910021421 monocrystalline silicon Inorganic materials 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 239000011241 protective layer Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000007790 scraping Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 239000002210 silicon-based material Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000003746 surface roughness Effects 0.000 description 1
- 229910021642 ultra pure water Inorganic materials 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/02—Silicon
- C01B33/037—Purification
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B33/00—After-treatment of single crystals or homogeneous polycrystalline material with defined structure
- C30B33/08—Etching
- C30B33/10—Etching in solutions or melts
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Crystallography & Structural Chemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Inorganic Chemistry (AREA)
- Silicon Compounds (AREA)
Abstract
The invention discloses a method for cleaning electronic grade polycrystalline silicon. The cleaning method of the electronic grade polysilicon comprises the following steps: and cleaning the silicon block by using the first to eighth cleaning liquids. The first cleaning solution is NaOH solution or KOH solution; the second cleaning solution is HNO3A mixture of HF and water; the third cleaning solution is HNO3HF, water, and HNO in the third cleaning liquid relative to the second cleaning liquid3Is low in concentration, HNO3The ratio to HF is higher; the fourth cleaning solution is NH4OH solution; the fifth cleaning solution is an HF solution; the sixth cleaning solution is H2O2A solution; the seventh cleaning solution is an HF solution, and compared with the fifth cleaning solution, the concentration of HF in the seventh cleaning solution is lower; the eighth cleaning liquid is water. The electronic grade polysilicon cleaning method can obviously improve the cleaning effect of the silicon block and enable the silicon block to be more round and smooth as a whole so as to facilitate downstream processing.
Description
Technical Field
The invention relates to the technical field of polycrystalline silicon production, in particular to a method for cleaning electronic grade polycrystalline silicon.
Background
The electronic grade polysilicon is a basic raw material of the integrated circuit industry, the production process mostly adopts an improved Siemens method, silicon rods are produced through CVD deposition, and then the silicon rods are made into silicon block products with different sizes through a series of post-treatment processes of crushing, cleaning, screening and the like. The downstream customer places the silicon block in a crucible and performs single crystal pulling by the czochralski method to obtain a semiconductor grade silicon wafer which can be used for manufacturing integrated circuits.
The process of silicon rod crushing involves a large amount of manual participation, and in the process of crushing and screening, various pollutants are inevitably introduced, and the silicon briquette needs to be cleaned to remove various surface impurities. Along with the improvement of the processing capability of the integrated circuit, the reduction of the line width leads to the continuous improvement of the requirement of the line width on the concentration of metal impurities of raw materials, otherwise, the problems of electric leakage and the like can be caused, the function of the integrated circuit is influenced, and the yield is reduced. All impurities on the surface of the silicon briquette can enter the silicon ingot body along with crystal pulling, and occasional quality problems are easily formed due to the characteristic of open manufacturing of a post-treatment process, so that the step of cleaning the silicon briquette is very important.
In the prior art, HNO is generally adopted for cleaning silicon blocks3And a cleaning liquid such as HF, which is used for removing various impurities adhering to the surface of the silicon block by etching the surface of the silicon block and is capable of reacting with various metal impurities to form a soluble product and dissolving the soluble product in the cleaning liquid. The silicon briquette is usually placed in a cleaning basket and rotates in a tank filled with cleaning liquid, the silicon briquette in the middle part often has insufficient contact degree with the cleaning liquid in the cleaning process, and meanwhile, when the cleaning liquid remained on the surface of the silicon briquette is cleaned by high-purity water in a subsequent tank, the remained liquid is not easy to clean. There is the patent to propose using rotatory washing basket or carrying out rocking of various forms to make silicon piece and washing liquid carry out abundant contact, nevertheless because silicon piece itself piles up comparatively inseparably, the effect is not good, still can lead to silicon piece to scraping to the washing basket simultaneously, makes partial non-silicon material mix into the product, causes the low reaches and can't use. Thus, the existing methods for cleaning silicon chunks still need to be improved.
Disclosure of Invention
The present invention is directed to solving, at least to some extent, one of the technical problems in the related art. To this end, it is an object of the present invention to provide an electronic grade polysilicon cleaning method. The electronic grade polysilicon cleaning method can obviously improve the cleaning effect of the silicon block and enable the silicon block to be more round and smooth as a whole so as to facilitate downstream processing.
In one aspect of the invention, a method for cleaning electronic grade polysilicon is provided. According to the embodiment of the invention, the electronic grade polycrystalline silicon cleaning method comprises the following steps:
(1) carrying out first cleaning treatment on a silicon block to be cleaned by using a first cleaning solution to obtain a first cleaned silicon block; the first cleaning solution is NaOH solution or KOH solution;
(2) carrying out second cleaning treatment on the first cleaned silicon briquette by using a second cleaning solution to obtain a second cleaned silicon briquette; the second cleaning solution is HNO3A mixture of HF and water;
(3) carrying out third cleaning treatment on the second cleaned silicon block by using a third cleaning solution to obtain a third cleaned silicon block; the third cleaning solution is HNO3HF, water, and HNO in the third cleaning solution relative to the second cleaning solution3Is low in concentration, HNO3The ratio to HF is higher.
(4) Carrying out fourth cleaning treatment on the third cleaned silicon block by using a fourth cleaning solution to obtain a fourth cleaned silicon block; the fourth cleaning solution is NH4OH solution;
(5) carrying out fifth cleaning treatment on the fourth cleaned silicon block by using a fifth cleaning solution to obtain a fifth cleaned silicon block; the fifth cleaning solution is an HF solution;
(6) carrying out sixth cleaning treatment on the fifth cleaned silicon briquette by using a sixth cleaning solution to obtain a sixth cleaned silicon briquette; the sixth cleaning solution is H2O2A solution;
(7) carrying out seventh cleaning treatment on the sixth cleaned silicon briquette by using a seventh cleaning solution to obtain a seventh cleaned silicon briquette; the seventh cleaning liquid is an HF solution, and compared with the fifth cleaning liquid, the concentration of HF in the seventh cleaning liquid is lower;
(8) carrying out eighth cleaning treatment on the seventh cleaned silicon briquette by using an eighth cleaning solution to obtain a cleaned silicon briquette product; the eighth cleaning liquid is water.
According to the electronic grade polysilicon cleaning method of the embodiment of the invention, firstly, alkaline liquor is utilized to carry out the first cleaning treatment on the silicon blocks to be cleaned. The inventor finds that the mechanism of corrosion of the silicon block by the alkali liquor and the mechanism of corrosion of the silicon block by the acid liquor are different, the corrosion of the silicon block by the alkali liquor is easier to start from the grain boundary direction, and the macroscopic expression of the corrosion of the silicon block by the alkali liquor is that the corrosion degree of the silicon block corroded by the alkali liquor is deeper at the protruding sharp corner position compared with the silicon block corroded by the acid liquor, so that the silicon block is more round and smooth as a whole, and the product is not easy to scratch an outer package or processing equipment in downstream use or processing.
The silicon block corroded by the alkali liquor is further cleaned by a second cleaning solution and a third cleaning solution, wherein the second cleaning solution and the third cleaning solution are HNO3HF, water, but HNO in the third cleaning liquid relative to the second cleaning liquid3Is low in concentration, HNO3The ratio to HF is higher. Using the second clearSince the washing liquid is a main etching liquid for silicon ingots, in actual production, the etching rate must be compatible with each other due to productivity problems, and thus, a problem of uneven etching rate occurs in different regions of silicon ingots. By adopting the third cleaning solution as the buffer solution, the problem that the surface morphology of the silicon block is not uniform due to corrosion and the impurities are not uniform can be effectively solved, and the problem that the residual acid liquor on the surface of the silicon block is not uniform can also be solved.
Further, use of NH4And the OH solution is used for carrying out fourth cleaning treatment on the silicon block subjected to the third cleaning. In this step, NH4The OH solution can effectively remove HNO on the surface of the silicon block3And the damage to subsequent equipment is avoided. At the same time, weakly basic NH4The OH can also etch the silicon block to form a thin oxide layer on the surface of the silicon block for subsequent treatment.
After the fourth cleaning treatment, the silicon block is further treated by HF solution with higher concentration and H2O2The solution and the lower concentration HF solution are sequentially subjected to fifth to seventh cleaning treatments. In the fifth cleaning treatment, the HF solution with higher concentration can re-etch the surface of the silicon block to form a hydrophobic surface. In the sixth cleaning treatment, H2O2An oxide layer can be formed on the surface of the silicon block, and H2O2The etching capability of the silicon block is weaker, and the simple shape adjustment can be carried out on the surface of the silicon block. In the seventh cleaning treatment, the HF solution with lower concentration can further etch the secondary oxide layer, and finally perform morphology adjustment and surface hydrophobic layer formation.
And further, washing the seventh washed silicon briquette by using water, and finally washing trace impurities and particles on the surface of the silicon briquette to obtain a washed silicon briquette product. By adopting the method of the invention to clean the silicon briquette, the obtained silicon briquette product has high cleanliness, almost no spot or stripe on the surface, more round and smooth whole body and convenient downstream processing.
In addition, the electronic grade polysilicon cleaning method according to the above embodiment of the invention may further have the following additional technical features:
in some embodiments of the present invention, the concentration of the first cleaning solution is 1 to 5 wt%.
In some embodiments of the present invention, the second cleaning solution comprises 50 to 65 wt% of HNO32-5 wt% of HF and the balance of water.
In some embodiments of the present invention, the third cleaning solution comprises 45-55 wt% HNO30.2 to 1 wt% of HF and the balance of water.
In some embodiments of the present invention, the concentration of the fourth cleaning solution is 0.5 to 3 wt%.
In some embodiments of the present invention, the concentration of the fifth cleaning solution is 0.05 to 0.4 wt%.
In some embodiments of the present invention, the concentration of the sixth cleaning solution is 1 to 5 wt%.
In some embodiments of the present invention, the concentration of the seventh cleaning solution is 0.03 to 0.3 wt%.
In some embodiments of the invention, the fourth cleaning process is performed with ultrasonic assistance.
In some embodiments of the present invention, the first cleaning process, the second cleaning process, the third cleaning process, the fourth cleaning process, the fifth cleaning process, the sixth cleaning process, the seventh cleaning process, and the eighth cleaning process are performed for 100 to 1200 seconds, respectively and independently.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a schematic flow diagram of an electronic grade polysilicon cleaning method in accordance with one embodiment of the present invention.
Detailed Description
The following describes embodiments of the present invention in detail. The following examples are illustrative only and are not to be construed as limiting the invention. The examples, where specific techniques or conditions are not indicated, are to be construed according to the techniques or conditions described in the literature in the art or according to the product specifications. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available. In the present invention, a solution of a certain solute refers to an aqueous solution of the solute, unless otherwise specified.
Furthermore, the terms "first", "second", "third", "fourth", "fifth", "sixth", "seventh", "eighth" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, features defined as "first", "second", "third", "fourth", "fifth", "sixth", "seventh", "eighth" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In one aspect of the invention, a method for cleaning electronic grade polysilicon is provided. Referring to fig. 1, the electronic grade polysilicon cleaning method according to the embodiment of the invention comprises:
s100: first cleaning treatment
In the step, a first cleaning treatment is carried out on the silicon briquette to be cleaned by using a first cleaning solution to obtain a first cleaned silicon briquette; the first cleaning solution is NaOH solution or KOH solution, preferably KOH solution. During the crushing process, sharp and acute angles are inevitably generated in the silicon blocks. The corrosion of acid liquor to the silicon block is isotropic corrosion, and the corrosion rate is irrelevant to the crystal phase. When the acid liquor is used for corroding the silicon block, the sharpness of the obtained product cannot be changed, and the acid liquor corrosion product can be used at downstream or easily scratch processing equipment or outer packaging bags or processing equipment. The mechanism of corrosion of the alkali liquor and the acid liquor on the silicon briquette is different, the alkali liquor corrosion is self-limiting corrosion, the corrosion of the alkali liquor on the silicon briquette is easier to start from the grain boundary direction, the corrosion rate at the sharp angle and other protruding parts is higher, and the macroscopic expression of the corrosion is that compared with the silicon briquette corroded by the acid liquor, the corrosion process of the silicon briquette after the alkali liquor corrosion is deeper at the protruding sharp angle position, so that the sharp degree of the silicon briquette is reduced, the silicon briquette is more round and smooth as a whole, and the product is not easy to scratch an outer package or processing equipment in downstream use or processing.
According to some embodiments of the present invention, the concentration of the first cleaning solution may be 1 to 5 wt%, such as 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, and the like. Therefore, the first cleaning liquid has better effect of reducing the sharpness of the silicon block.
S200: second cleaning treatment
In the step, second cleaning treatment is carried out on the first cleaned silicon briquette by using a second cleaning solution to obtain a second cleaned silicon briquette; the second cleaning solution is HNO3HF, water.
S300: third cleaning treatment
In the step, third cleaning treatment is carried out on the second cleaned silicon block by using a third cleaning solution to obtain a third cleaned silicon block; the third cleaning solution is HNO3HF, water, and HNO in the third cleaning liquid relative to the second cleaning liquid3Is low in concentration, HNO3The ratio to HF is higher.
According to the embodiment of the invention, the second cleaning liquid is used as the main etching liquid of the silicon briquette, and the problem of uneven etching speed is generated in different areas of the silicon briquette because the etching speed needs to be compatible with the production rate in the actual production. By adopting the third cleaning solution as the buffer solution, the problem that the surface morphology of the silicon block is not uniform due to corrosion and the impurities are not uniform can be effectively solved, and the problem that the residual acid liquor on the surface of the silicon block is not uniform can also be solved.
According to some embodiments of the present invention, the second cleaning solution may include 50 to 65 wt% of HNO32-5 wt% of HF and the balance of water. Specifically, HNO is contained in the second cleaning liquid3The content of (b) may be 50 wt%, 55 wt%, 60 wt%, 65 wt%, etc., and the content of HF may be 2 wt%, 3 wt%, 4 wt%, 5 wt%, etc. The third cleaning solution may include 45 to 55 wt% of HNO30.2 to 1 wt% of HF and the balance of water. Specifically, HNO in the third cleaning solution3May be present in an amount of 45 wt%, 50 wt%, 55 wt%% and the like, and the content of HF may be 0.2 wt%, 0.5 wt%, 0.8 wt%, 1 wt%, and the like. By adjusting the second cleaning solution and the third cleaning solution to be the compositions, the uniformity of the surface morphology of the silicon block can be further improved, and the generation of spots and spots on the surface of the silicon block can be avoided. Compared with the spots and specks of about 1 percent on the surface of the silicon briquette in the existing silicon briquette cleaning method, the silicon briquette is cleaned by adopting the method of the invention, the obtained silicon briquette product has high cleanliness, and the surface almost has no spots or specks.
S400: fourth cleaning treatment
In the step, fourth cleaning treatment is carried out on the third cleaned silicon block by using a fourth cleaning solution to obtain a fourth cleaned silicon block; the fourth cleaning solution is NH4And (4) OH solution. In this step, NH4The OH solution can effectively remove HNO on the surface of the silicon block3. If the surface of the silicon block is HNO3The removal is not thorough, and when the silicon single crystal silicon rod is used in the downstream, the crucible can be damaged in the crystal pulling process, the protective layer on the surface of the crucible is damaged, and finally various impurities of the prepared silicon single crystal rod exceed the standard. At the same time, weakly basic NH4The OH can also etch the silicon block to form a thin oxide layer on the surface of the silicon block for subsequent treatment.
According to some embodiments of the present invention, the concentration of the fourth cleaning solution may be 0.5 to 3 wt%, such as 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, etc. Thus, HNO is formed on the surface of the silicon block3The removal effect is better.
According to some embodiments of the invention, the fourth cleaning process is performed under ultrasonic assistance. Therefore, the flow of the cleaning liquid can be effectively enhanced, the cleaning liquid enters the interior of the silicon blocks which are tightly stacked, and the cleaning effect of the silicon blocks is improved. Specifically, the ultrasonic generator can be placed in the cleaning tank due to NH in the cleaning solution4And residual acid on the surface of the silicon block can be removed in time due to the existence of OH, so that the ultrasonic wave generating device cannot be corroded, and the metal ions in the ultrasonic wave generating device are dissolved out to pollute the silicon block.
S500: fifth cleaning treatment
In the step, fifth cleaning treatment is carried out on the fourth cleaned silicon block by using a fifth cleaning solution to obtain a fifth cleaned silicon block; the fifth cleaning solution is an HF solution. And carrying out the fifth cleaning treatment on the silicon block subjected to the fourth cleaning by using an HF solution, so that the surface of the silicon block can be re-etched and a hydrophobic surface can be formed.
According to some embodiments of the present invention, the concentration of the fifth cleaning solution may be 0.05 to 0.4 wt%, such as 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, and the like. Therefore, the effects of re-etching the surface of the silicon block and forming a hydrophobic surface can be further improved.
S600: sixth cleaning treatment
In the step, sixth cleaning treatment is carried out on the fifth cleaned silicon briquette by using a sixth cleaning solution to obtain a sixth cleaned silicon briquette; the sixth cleaning solution is H2O2And (3) solution. H2O2An oxide layer can be formed on the surface of the silicon block, and H2O2The etching capability of the silicon block is weaker, and the simple shape adjustment can be carried out on the surface of the silicon block.
According to some embodiments of the present invention, the concentration of the sixth cleaning solution may be 1 to 5 wt%, for example, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, etc. Therefore, the formation of the oxide layer on the surface of the silicon block and the adjustment of the surface appearance can be further facilitated.
S700: seventh cleaning treatment
In the step, seventh cleaning treatment is carried out on the sixth cleaned silicon briquette by using seventh cleaning solution to obtain a seventh cleaned silicon briquette; the seventh cleaning liquid is an HF solution, and the concentration of HF in the seventh cleaning liquid is lower than that in the fifth cleaning liquid. The HF solution with lower concentration can further etch the secondary oxide layer, and finally perform shape adjustment and surface hydrophobic layer formation.
According to some embodiments of the present invention, the concentration of the seventh cleaning liquid may be 0.03 to 0.3 wt%, for example, 0.03 wt%, 0.06 wt%, 0.1 wt%, 0.15 wt%, 0.2 wt%, 0.25 wt%, 0.3 wt%. Therefore, the method is further beneficial to the formation of the hydrophobic layer on the surface of the silicon block and the adjustment of the surface appearance.
Through the fourth primer cleaning treatment, the etching efficiency of impurities and the surface can be effectively improved, the gradually-reduced etching rate can effectively adjust the surface state, the difference of surface roughness caused by the etching speed at different positions is avoided, the appearance (color difference, color spots and the like of the surface) of the silicon block can be greatly improved, the detection deviation caused by the difference of adsorption effects of different surfaces can be improved, and in addition, the possibility of residue of the adsorbed residual acid is further reduced after the slow-release etching is repeated twice.
S800: eighth cleaning treatment
Performing eighth cleaning treatment on the seventh cleaned silicon briquette by using an eighth cleaning solution to obtain a cleaned silicon briquette product; the eighth cleaning liquid is water. And washing the seventh washed silicon briquette by using water, and finally washing trace impurities and particles on the surface of the silicon briquette to obtain a washed silicon briquette product.
According to some embodiments of the present invention, the eighth cleaning liquid is preferably ultrapure water having a resistivity of not less than 18M Ω · cm. Therefore, the cleaning effect of the silicon briquette product is better.
According to some embodiments of the present invention, the first cleaning process, the second cleaning process, the third cleaning process, the fourth cleaning process, the fifth cleaning process, the sixth cleaning process, the seventh cleaning process, and the eighth cleaning process may be performed for 100 to 1200s, for example, 100s, 200s, 300s, 400s, 500s, 600s, 700s, 800s, 900s, 1000s, 1100s, 1200s, and the like, respectively. Therefore, the cleaning effect of the silicon block is better.
In addition, according to some embodiments of the present invention, the manner in which the above-described first to eighth cleaning processes are performed is not particularly limited, and for example, the silicon ingot to be cleaned may be placed in a cleaning basket, and the cleaning basket may be shaken right and left or in a figure-8 shape in a cleaning tank filled with the respective cleaning liquids so that the silicon ingot sufficiently contacts the cleaning liquids.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (10)
1. An electronic grade polysilicon cleaning method is characterized by comprising the following steps:
(1) carrying out first cleaning treatment on a silicon block to be cleaned by using a first cleaning solution to obtain a first cleaned silicon block; the first cleaning solution is NaOH solution or KOH solution;
(2) carrying out second cleaning treatment on the first cleaned silicon briquette by using a second cleaning solution to obtain a second cleaned silicon briquette; the second cleaning solution is HNO3A mixture of HF and water;
(3) carrying out third cleaning treatment on the second cleaned silicon block by using a third cleaning solution to obtain a third cleaned silicon block; the third cleaning solution is HNO3HF, water, and HNO in the third cleaning solution relative to the second cleaning solution3Is low in concentration, HNO3The ratio to HF is higher;
(4) carrying out fourth cleaning treatment on the third cleaned silicon block by using a fourth cleaning solution to obtain a fourth cleaned silicon block; the fourth cleaning solution is NH4OH solution;
(5) carrying out fifth cleaning treatment on the fourth cleaned silicon block by using a fifth cleaning solution to obtain a fifth cleaned silicon block; the fifth cleaning solution is an HF solution;
(6) using the sixth cleaning liquid pairCarrying out sixth cleaning treatment on the fifth cleaned silicon briquette to obtain a sixth cleaned silicon briquette; the sixth cleaning solution is H2O2A solution;
(7) carrying out seventh cleaning treatment on the sixth cleaned silicon briquette by using a seventh cleaning solution to obtain a seventh cleaned silicon briquette; the seventh cleaning liquid is an HF solution, and compared with the fifth cleaning liquid, the concentration of HF in the seventh cleaning liquid is lower;
(8) carrying out eighth cleaning treatment on the seventh cleaned silicon briquette by using an eighth cleaning solution to obtain a cleaned silicon briquette product; the eighth cleaning liquid is water.
2. The method for cleaning electronic grade polysilicon according to claim 1, wherein the concentration of the first cleaning solution is 1-5 wt%.
3. The electronic grade polysilicon cleaning method according to claim 1, wherein the second cleaning solution comprises 50-65 wt% of HNO32-5 wt% of HF and the balance of water.
4. The electronic grade polysilicon cleaning method according to claim 1, wherein the third cleaning solution comprises 45-55 wt% HNO30.2 to 1 wt% of HF and the balance of water.
5. The method for cleaning electronic grade polysilicon according to claim 1, wherein the concentration of the fourth cleaning solution is 0.5 to 3 wt%.
6. The method for cleaning electronic grade polysilicon according to claim 1, wherein the concentration of the fifth cleaning solution is 0.05 to 0.4 wt%.
7. The method for cleaning electronic grade polysilicon according to claim 1, wherein the concentration of the sixth cleaning liquid is 1-5 wt%.
8. The method for cleaning electronic grade polysilicon according to claim 1, wherein the concentration of the seventh cleaning solution is 0.03-0.3 wt%.
9. The method for cleaning electronic grade polysilicon according to any one of claims 1 to 8, wherein the fourth cleaning treatment is carried out under the assistance of ultrasonic waves.
10. The method for cleaning electronic grade polysilicon according to any one of claims 1 to 8, wherein the first cleaning process, the second cleaning process, the third cleaning process, the fourth cleaning process, the fifth cleaning process, the sixth cleaning process, the seventh cleaning process and the eighth cleaning process are performed for 100 to 1200 seconds respectively and independently.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011290207.9A CN112390259B (en) | 2020-11-17 | 2020-11-17 | Electronic grade polysilicon cleaning method |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011290207.9A CN112390259B (en) | 2020-11-17 | 2020-11-17 | Electronic grade polysilicon cleaning method |
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| Publication Number | Publication Date |
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| CN112390259A CN112390259A (en) | 2021-02-23 |
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Address after: 221004 No.66, Yangshan Road, Xuzhou Economic and Technological Development Zone, Jiangsu Province Patentee after: Jiangsu Xinhua Semiconductor Technology Co.,Ltd. Address before: 221004 No.66, Yangshan Road, Xuzhou Economic and Technological Development Zone, Jiangsu Province Patentee before: JIANGSU XINHUA SEMICONDUCTOR MATERIALS TECHNOLOGY CO.,LTD. |
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Application publication date: 20210223 Assignee: Yangzhou Xinhua Semiconductor Technology Co.,Ltd. Assignor: Jiangsu Xinhua Semiconductor Technology Co.,Ltd. Contract record no.: X2024980007191 Denomination of invention: Electronic grade polycrystalline silicon cleaning method Granted publication date: 20220128 License type: Common License Record date: 20240614 |