Preparation method of silicon fine polishing liquid with low haze and low particle defects

Abstract

The invention relates to a preparation method of a silicon fine polishing solution with low haze and low particle defects. The silicon fine polishing solution contains grinding particles, an alkaline compound, a high-molecular polymer, a surfactant and water. The preparation method of the silicon fine polishing liquid with the low haze and the low particle defects comprises preparation of at least one premixed liquid and preparation of finished product liquid, one premixed liquid comprises an alkaline compound, a high-molecular polymer and water, materials are sequentially added according to the sequence of the water, the high-molecular polymer and the alkaline compound, and the finished product liquid is prepared. And after the premixed liquid is prepared, the sufficient dissolution of the premixed liquid is ensured by detecting the pH value, the number of large particles greater than or equal to 0.50 mu m and the viscosity of the premixed liquid. Wherein the step of preparing the finished product liquid comprises the step of uniformly mixing the premixed liquid and the grinding material, and the circulating stirring time is not less than 3 times.

Description

Technical Field

[0001] The invention relates to the technical field of chemical mechanical polishing liquid, in particular to a silicon polishing liquid and a preparation method thereof. Background Art

[0002] With the development of the semiconductor industry, the demand for surface quality after polishing silicon wafers is becoming increasingly stringent. As the polishing fluid used in the final polishing step for silicon wafers, silicon polishing fluids are subject to extremely high performance requirements, such as the absence of polishing marks and polishing haze, low particle defects, low surface roughness, and low surface and bulk metal content. To achieve excellent surface quality, in addition to formula design and optimization, the preparation process of the polishing fluid also plays a crucial role in the surface quality of the polished silicon wafer. Therefore, there is a particular need to provide a method for preparing silicon polishing fluids that can achieve low haze and particle defects to meet the requirements of advanced manufacturing processes. Summary of the Invention

[0003] In order to solve the above technical problems, the present invention provides a method for preparing a silicon polishing liquid with low haze and low particle defects.

[0004] In order to solve the above problems, the present invention is achieved through the following technical solutions:

[0005] According to the present invention, a method for preparing a silicon polishing liquid with low haze and low particle defects is provided. The silicon polishing liquid comprises abrasive particles, an alkaline compound, a high molecular polymer, a surfactant and water.

[0006] The abrasive particles in the silicon polishing liquid with low haze and low particle defects are selected from nano-colloidal silicon dioxide.

[0007] Furthermore, the primary particle size of the abrasive particles is greater than 10 nm and less than 60 nm, preferably greater than 20 nm and less than 50 nm, and more preferably greater than 30 nm and less than 40 nm.

[0008] Furthermore, the concentration of the abrasive particles is 4-10 wt%, preferably 8-10 wt%.

[0009] The alkaline compound in the silicon polishing liquid with low haze and low particle defects is selected from one or more of tetramethylammonium hydroxide (TMAH), piperazine, 1-(2-aminoethyl)piperazine (AEP), 1,4-bis(3-aminopropyl)piperazine, 1,4-bis(2-hydroxyethyl)piperazine, n-propylamine, isopropylamine, diglycolamine, isopropanolamine, ethylenediamine, choline hydroxide, and ammonia water.

[0010] Furthermore, the concentration of the alkaline compound is 0.2-3 wt %, preferably 1.0-2.5 wt %, and more preferably 1.8-2.5 wt %.

[0011] The high molecular weight polymer in the silicone polishing liquid with low haze and low particle defects is selected from one or more of polyvinyl alcohol (PVA), hydroxyethyl cellulose (HEC), PEO-PPO-PPEO (PE6800), polyacrylamide and its derivatives, polyvinyl pyrrolidone (PVP), and polyethylene glycol (PEG).

[0012] Furthermore, the concentration of the high molecular weight polymer is 0.001-1 wt%, preferably 0.2-0.8 wt%, and more preferably 0.4-0.6 wt%.

[0013] The surfactant in the silicone polishing liquid with low haze and low particle defects is selected from one or more of polyoxyethylene decyl ether, polyoxyethylene lauryl ether, and polyoxyethylene lauryl ether ammonium sulfate.

[0014] Furthermore, the concentration of the surfactant is 0.005-0.1 wt%, preferably 0.005-0.05 wt%, and more preferably 0.01-0.03 wt%.

[0015] Furthermore, the pH value of the silicon polishing liquid with low haze and low particle defects is 10.0-11.0.

[0016] Furthermore, the method for preparing the silicon polishing liquid with low haze and low particle defects includes the preparation of at least one premixed liquid and the preparation of a finished liquid.

[0017] Furthermore, the preparation of the premixed liquid of the silicon polishing liquid with low haze and low particle defects comprises sequentially adding water, a high molecular polymer, and an alkaline compound into a premixing tank stirred at 300 rpm, and stirring for at least 1.5 hours to obtain the premixed liquid.

[0018] Furthermore, the weight percentage of the alkaline compound in the premixed liquid of the silicon polishing liquid with low haze and low particle defects is higher than the weight percentage of the high molecular weight polymer.

[0019] Furthermore, if the silicon polishing liquid with low haze and low particle defects contains two or more powdered polymers, it is prepared into premixed liquid 2 according to the preparation method of the above premixed liquid.

[0020] Furthermore, the method for preparing the silicon polishing liquid with low haze and low particle defects comprises adding all liquid materials or premixed liquids into a premixing kettle in sequence to prepare a total premixed liquid, and finally adding abrasives to the total premixed liquid to prepare a finished liquid.

[0021] Furthermore, the method for preparing the silicon polishing liquid with low haze and low particle defects includes stirring the total premixed liquid and the finished liquid for a cycle time of not less than 3 times.

[0022] Furthermore, the method for preparing the silicon polishing liquid with low haze and low particle defects includes filtering the finished liquid through a 0.5 μm filter element and discharging the material.

[0023] Beneficial technical effects:

[0024] The present invention combines formula optimization with preparation process optimization to obtain a silicon polishing liquid with low haze and low particle defects. The formula optimization includes compounding multiple polymers, compounding polymers with surfactants, and controlling the concentration ratio of the compounding to achieve the requirements of low haze and low particle defects. The preparation process optimization includes the preparation of premixed liquid and finished liquid, wherein the premixed liquid preparation includes adding water, polymers, and alkaline compounds to a premixing tank in sequence and stirring for at least 1.5 hours; the finished liquid preparation includes adding abrasives to the total premixed liquid, stirring the cycle time for not less than 3 times, and filtering through a 0.5μm filter element to obtain the finished liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The figure is a process flow chart for preparing the silicon polishing liquid of the present invention. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, rather than all embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] Unless otherwise specifically stated, the numerical value set forth in these embodiments does not limit the scope of the present invention. Technology and methods known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology and methods should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments can have different values.

[0028] In the following examples, the experimental methods without specific conditions are generally measured according to national standards; if there is no corresponding national standard, the general standard requirements or general methods are used.

[0029] Example 1

[0030] First, 10 wt% deionized water was added to premixing tank 1, the speed was set to 300 rpm, stirring was started, 2 wt% powdered HEC was slowly added to premixing tank 1, and 2.9 wt% liquid TMAH was poured into premixing tank 1, and timed stirring was performed for 5 hours to prepare premixed solution 1; then 1 wt% deionized water was added to premixing tank 2, the speed was set to 300 rpm, stirring was started, 0.001 wt% powdered PVP was slowly added to premixing tank 2, and 0.1 wt% liquid TMAH was poured into premixing tank 2, and timed stirring was performed for 1.5 hours to prepare premixed solution 2; then take 34.149wt% deionized water and add it to the finished product tank, set the speed to 72rpm, start stirring, add premix 1 and premix 2 to the finished product tank in turn, stir for 50min, then add 0.3wt% polyacrylamide and 0.05wt% polyethylene glycol in turn, stir for 20min, then add 1.5wt% ammonia water, stir for 15min, then add 48wt% nano-silica (solid content 20wt%), increase the speed to 108rpm, start circulation, circulate and stir for 3 times, and then pass through a 0.5μm filter element to prepare a silicon polishing liquid.

[0031] Example 2

[0032] First, 10 wt% deionized water was added to premixing tank 1, the speed was set to 300 rpm, stirring was started, 2 wt% powdered HEC was slowly added to premixing tank 1, and 3 wt% liquid TMAH was poured into premixing tank 1, and timed stirring was performed for 5 hours to prepare premixed solution 1; then 10 wt% deionized water was added to premixing tank 2, the speed was set to 300 rpm, stirring was started, 0.001 wt% powdered PVP was slowly added to premixing tank 2, and 2 wt% flaky piperazine was poured into premixing tank 2, and timed stirring was performed for 1.5 hours to prepare premixed solution 2; then 23.144 wt% deionized water is added to the finished product tank, the speed is set to 72 rpm, and stirring is started. Premix 1 and premix 2 are added to the finished product tank in sequence. After stirring for 50 minutes, 0.3wt% polyacrylamide, 0.05wt% polyethylene glycol, and 0.005wt% polyoxyethylene decyl ether are added in sequence. After stirring for 20 minutes, 1.5wt% ammonia water is added. After stirring for 15 minutes, 48wt% nano-silica (solid content 20wt%) is added. The speed is increased to 108 rpm, and the circulation is started. After circulated and stirred for 3 times, the material is discharged through a 0.5μm filter element to prepare a silicon polishing liquid.

[0033] Example 3

[0034] First, 10 wt% deionized water was added to premixing tank 1, the speed was set to 300 rpm, stirring was started, 2 wt% powdered HEC was slowly added to premixing tank 1, and 3 wt% liquid TMAH was poured into premixing tank 1, and timed stirring was performed for 5 h to prepare premixed solution 1; then 10 wt% deionized water was added to premixing tank 2, the speed was set to 300 rpm, stirring was started, 0.001 wt% powdered PVP was slowly added to premixing tank 2, and 2 wt% flaky piperazine was poured into premixing tank 2, and timed stirring was performed for 1.5 h to prepare premixed solution 2; then 23.139 wt% deionized water is added to the finished product tank, the speed is set to 72 rpm, and stirring is started. Premix 1 and premix 2 are added to the finished product tank in sequence. After stirring for 50 minutes, 0.3wt% polyacrylamide, 0.05wt% polyethylene glycol, and 0.01wt% polyoxyethylene decyl ether are added in sequence. After stirring for 20 minutes, 1.5wt% ammonia water is added. After stirring for 15 minutes, 48wt% nano-silica (solid content 20wt%) is added. The speed is increased to 108 rpm, and the circulation is started. After 3 cycles of stirring, the material is discharged through a 0.5μm filter element to prepare a silicon polishing liquid.

[0035] Example 4

[0036] First, 10 wt% deionized water was added to premixing tank 1, the speed was set to 300 rpm, stirring was started, 2.5 wt% powdered HEC was slowly added to premixing tank 1, and 3 wt% liquid TMAH was poured into premixing tank 1, and timed stirring was performed for 5 h to prepare premixed solution 1; then 10 wt% deionized water was added to premixing tank 2, the speed was set to 300 rpm, stirring was started, 0.001 wt% powdered PVP was slowly added to premixing tank 2, and 2 wt% flaky piperazine was poured into premixing tank 2, and timed stirring was performed for 1.5 h to prepare premixed solution 2; then 22.63 9wt% deionized water was added to the finished product tank, the speed was set to 72rpm, stirring was started, premixed liquid 1 and premixed liquid 2 were added to the finished product tank in sequence, and stirred for 50min, and then 0.3wt% polyacrylamide, 0.05wt% polyethylene glycol, and 0.01wt% polyoxyethylene decyl ether were added in sequence, and stirred for 20min, and then 1.5wt% ammonia water was added. After stirring for 15min, 48wt% nano-silica (solid content 20wt%) was added, the speed was increased to 108rpm, the circulation was started, and after 3 cycles of stirring, the material was discharged through a 0.5μm filter element to prepare a silicon polishing liquid.

[0037] Example 5

[0038] First, 10 wt% deionized water was added to premixing tank 1, the speed was set to 300 rpm, stirring was started, 2 wt% powdered HEC was slowly added to premixing tank 1, and 3 wt% liquid TMAH was poured into premixing tank 1, and timed stirring was performed for 5 hours to prepare premixed solution 1; then 10 wt% deionized water was added to premixing tank 2, the speed was set to 300 rpm, stirring was started, 0.001 wt% powdered PVP was slowly added to premixing tank 2, and 2 wt% flaky piperazine was poured into premixing tank 2, and timed stirring was performed for 1.5 hours to prepare premixed solution 2; then 23.134 wt% deionized water was added In the finished product tank, the speed is set to 72 rpm, stirring is started, and premixed liquid 1 and premixed liquid 2 are added to the finished product tank in sequence. After stirring for 50 minutes, 0.3 wt% polyacrylamide, 0.05 wt% polyethylene glycol, 0.01 wt% polyoxyethylene decyl ether, and 0.005 wt% polyoxyethylene silyl ether ammonium sulfate are added in sequence. After stirring for 20 minutes, 1.5 wt% ammonia water is added. After stirring for 15 minutes, 48 ​​wt% nano-silica (solid content 20 wt%) is added. The speed is increased to 108 rpm, the circulation is started, and the circulation stirring is repeated 3 times and the material is discharged through a 0.5 μm filter element to prepare a silicon polishing liquid.

[0039] Comparative Example 1

[0040] First, 10 wt% deionized water was added to premixing tank 1, the speed was set to 300 rpm, stirring was started, 2 wt% powdered HEC was slowly added to premixing tank 1, and 2.9 wt% liquid TMAH was poured into premixing tank 1, and timed stirring was performed for 5 hours to prepare premixed solution 1; then 1 wt% deionized water was added to premixing tank 2, the speed was set to 300 rpm, stirring was started, 0.001 wt% powdered PVP was slowly added to premixing tank 2, and 0.1 wt% liquid TMAH was poured into premixing tank 2, and timed stirring was performed for 1.5 hours to prepare premixed solution 2; then take 34.149wt% deionized water and add it to the finished product tank, set the speed to 72rpm, start stirring, add premix 1 and premix 2 to the finished product tank in turn, stir for 20min, then add 0.3wt% polyacrylamide and 0.05wt% polyethylene glycol in turn, stir for 20min, then add 1.5wt% ammonia water, stir for 10min, then add 48wt% nano-silica (solid content 20wt%), increase the speed to 108rpm, start circulation, circulate and stir twice, and then pass through a 0.5μm filter element to prepare a silicon polishing liquid.

[0041] Comparative Example 2

[0042] First, 10 wt% deionized water was added to premixing tank 1, the speed was set to 300 rpm, stirring was started, 2 wt% powdered HEC was slowly added to premixing tank 1, and 2.9 wt% liquid TMAH was poured into premixing tank 1, and timed stirring was performed for 1.5 h to prepare premixed solution 1; then 1 wt% deionized water was added to premixing tank 2, the speed was set to 300 rpm, stirring was started, 0.001 wt% powdered PVP was slowly added to premixing tank 2, and 0.1 wt% liquid TMAH was poured into premixing tank 2, and timed stirring was performed for 1.5 h to prepare premixed solution 1. Liquid 2; then 34.149wt% deionized water was added to the finished product tank, the speed was set to 72rpm, the stirring was started, and the premixed liquid 1 and premixed liquid 2 were added to the finished product tank in sequence. After stirring for 20min, 0.3wt% polyacrylamide and 0.05wt% polyethylene glycol were added in sequence. After stirring for 20min, 1.5wt% ammonia water was added. After stirring for 10min, 48wt% nano-silica (solid content 20wt%) was added. The speed was increased to 108rpm, the circulation was started, and the material was discharged through a 0.5μm filter element after circulating and stirring once to prepare a silicon polishing liquid.

[0043] Application Example 1

[0044] Polishing process:

[0045] Polishing machine: Shanghai Zhiling polishing machine (CP-1280B / DP)

[0046] Polishing pressure: 125Kg

[0047] Blasting head speed: 29rpm

[0048] Throwing disk speed: 30rpm

[0049] Dilution ratio: Slurry: DIW = 1L: 30L

[0050] Polishing liquid flow rate: 1.5L / min

[0051] Polishing pad: 7355-000FE (Chiyoda, Japan)

[0052] Polished wafer: thickness 725μm, P type (100), resistivity > 100Ω, diameter 200mm

[0053] Polishing temperature: 28℃-32℃

[0054] Polishing time: 7 minutes

[0055] Cleaning conditions: A cleaning solution (SC-1 cleaning solution) was prepared by mixing ammonia (29 wt % concentration): hydrogen peroxide (31 wt % concentration): deionized water in a ratio of 1:3:30 (volume ratio) to clean the polished silicon wafer surface.

[0056] Table 1. Comparison of post-CMP test results of the embodiment and comparative example

[0057] Polishing mist Particle defects Example 1 95％ 63wt% Example 2 88％ 50％ Example 3 82％ 38％ Example 4 98％ 20％ Example 5 90％ 31％ Comparative Example 1 100％ 100％ Comparative Example 2 101％ 137％

[0058] Comparing Example 1 with Comparative Examples 1-2, it can be seen that if the stirring time during the preparation of the silicon polishing liquid is insufficient, the premixed liquid and the abrasive cannot be fully mixed and evenly, which will result in poor particle defects on the silicon wafer surface after CMP. Comparing Example 1 with Examples 2-3, it can be seen that the addition of alkaline compounds and surfactants can further reduce particle defects and haze. Comparing Example 3 with Example 4, it can be seen that appropriately increasing the concentration of the high molecular weight polymer HEC can further reduce particle defects. Comparing Example 3 with Example 5, it can be seen that the addition of a second type of surfactant can also further reduce particle defects.

[0059] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A silicon polishing liquid with low haze and low particle defects, comprising abrasive particles, an alkaline compound, a high molecular polymer, a surfactant and water; The abrasive particles are selected from colloidal nano-silicon dioxide; The alkaline compound is selected from one or more of tetramethylammonium hydroxide (TMAH), piperazine, 1-(2-aminoethyl)piperazine (AEP), 1,4-bis(3-aminopropyl)piperazine, 1,4-bis(2-hydroxyethyl)piperazine, n-propylamine, isopropylamine, diglycolamine, isopropanolamine, ethylenediamine, choline hydroxide, and ammonia water. The high molecular polymer is selected from one or more of polyvinyl alcohol (PVA), hydroxyethyl cellulose (HEC), PEO-PPO-PPEO (PE6800), polyacrylamide and its derivatives, polyvinyl pyrrolidone (PVP), and polyethylene glycol (PEG). The surfactant is selected from one or more of polyoxyethylene decyl ether, polyoxyethylene lauryl ether, and polyoxyethylene lauryl ether ammonium sulfate.

2. The silicon polishing liquid according to claim 1, characterized in that The primary particle size of the nano-colloidal silica is 30-40 nm, and the content of the abrasive particles is 4-10 wt %.

3. The silicon polishing liquid according to claim 1, characterized in that The content of the basic compound is 0.2-3 wt%.

4. The silicon polishing liquid according to claim 1, characterized in that The content of the high molecular weight polymer is 0.001-1 wt%.

5. The silicon polishing liquid according to claim 1, characterized in that The content of the surfactant is 0.005-0.1 wt%.

6. The silicon polishing liquid according to claim 1-5, characterized in that The pH of the polishing liquid is 10.0-11.

0.

7. A method for preparing a silicon polishing liquid with low haze and low particle defects, comprising the preparation of at least one premixed liquid and a finished liquid.

8. The method for preparing silicon polishing liquid according to claim 7, wherein: The preparation of the premix solution comprises sequentially adding water, a high molecular weight polymer, and an alkaline compound into a premix tank stirred at 300 rpm and stirring for at least 1.5 hours.

9. The method for preparing silicon polishing liquid according to claim 7-8, characterized in that: The weight percentage of the basic compound is higher than the weight percentage of the high molecular weight polymer.

10. The method for preparing silicon polishing liquid according to claims 7-9, characterized in that: If the silicone polishing liquid contains two or more powdered polymers, the premixed liquid 2 is prepared according to the method described in claim 8.

11. The method for preparing a silicon polishing liquid according to claims 7-10, characterized in that: All liquid materials or premixed liquids are added into the premixing kettle in sequence to prepare a total premixed liquid, and finally the abrasive is added to the total premixed liquid to prepare a finished liquid.

12. The method for preparing silicon polishing liquid according to claims 7-11, characterized in that: The stirring cycle time of the total premix liquid and finished liquid shall be no less than 3 times.

13. The method for preparing silicon polishing liquid according to claims 7-12, characterized in that: The finished liquid is filtered out through a 0.5μm filter element.

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