CN118460119A - Chemical mechanical polishing liquid, application thereof and chemical mechanical polishing method - Google Patents

Abstract

The invention provides a chemical mechanical polishing solution, which is an aqueous solution containing the following components: 2 to 12. 12 wt percent of high-purity abrasive, 0.01 to 0.5. 0.5 wt percent of polyvinylpyrrolidone, 0.001 to 0.08. 0.08 wt percent of alkyl glycoside surfactant and 0.1 to 1. 1 wt percent of glycerin derivative. The invention also provides application of the chemical mechanical polishing solution and a chemical mechanical polishing method of the silicon wafer. The polishing solution provided by the invention can obtain the surface state of the polished silicon wafer through the synergistic effect of the components, and can effectively reduce the defects, roughness and haze value of the LPD. In addition, the polishing solution has the advantages of small component quantity, good economy, simple preparation method, easy control of process and great industrial practical value.

Description

Chemical mechanical polishing liquid, application thereof and chemical mechanical polishing method

Technical Field

The invention relates to the technical field of Chemical Mechanical Polishing (CMP), in particular to a chemical mechanical polishing liquid and application thereof, and also relates to a chemical mechanical polishing method of a silicon wafer.

Background

Currently, the semiconductor industry is rapidly developed, and material update iteration is performed, and second-generation semiconductor materials represented by GaAs and InP and third-generation semiconductor materials represented by GaN and SiC are emerging. However, the first generation of silicon-based semiconductor materials remained the most widely used semiconductor materials with the greatest yield, and more than 90% of semiconductor products were fabricated using silicon-based materials. Silicon wafers (also known as "silicon wafers") are key raw materials for the production of semiconductor products, and the production and processing of silicon wafers is a key element in the upstream industrial chain of semiconductors.

The processing process flow of the silicon wafer generally comprises the following steps: single crystal silicon ingot, cutting, orientation, barreling, corrosion, slicing, grinding sheet, chamfering, chemical thinning, polishing, cleaning and detection. The polishing process can repair the damage and the defect on the surface of the silicon wafer in the previous process, and the thickness and the surface cleanliness of the silicon wafer which meet the follow-up production are obtained, so that the polishing process is a crucial step in the processing process.

Polishing of silicon wafers is generally divided into three times, i.e., rough polishing, medium polishing, and fine polishing. The aim of rough polishing and medium polishing is mainly to efficiently and rapidly remove a large number of damaged layers and obtain a certain surface cleanliness; finish polishing is the last step of silicon wafer processing, and is mainly used for completely removing a damaged layer, so that extremely high surface cleanliness is obtained. The surface state of the silicon wafer before leaving the factory is directly determined by the fine polishing effect, and the electrical characteristics of the subsequent processing device can be affected. Therefore, the fine polishing process of the silicon wafer is critical.

Japanese patent JP 4251516B2 discloses that a lower roughness of the final finish can be obtained using abrasive grains having a large and small particle size, but the polishing material is a substrate (metal compound material) of a memory disk, which is quite different from a silicon substrate. Chinese patent CN 113631679B discloses a method for improving Haze (Haze) value after polishing of silicon wafers using organic acid, but it has no specific Haze value data, and the effect of organic acid on defects and roughness is not mentioned. Chinese patent application CN 117801684a discloses a fine polishing liquid composed of high purity silica sol, polymer binder, two amine accelerators, polymer thickener, copolymer anti-crystallization agent, pH regulator, which can obtain lower roughness and haze value, but has complex composition and higher production and raw material cost.

Disclosure of Invention

In order to make up the defects in the prior art, the invention aims to provide a chemical mechanical polishing liquid which has simple components and low cost, is used for chemical mechanical polishing of a silicon wafer, can effectively improve the surface state of the polished wafer, and can obtain lower LPD defects (Light point defect, light point defects), roughness and haze values.

Another object of the invention is to provide the use of said chemical mechanical polishing liquid.

It is yet another object of the present invention to provide a chemical mechanical polishing method for silicon wafers.

In a first aspect, the present invention provides a chemical mechanical polishing solution, which is an aqueous solution comprising: 2 to 15. 15 wt percent of high-purity abrasive, 0.01 to 0.5. 0.5 wt percent of polyvinylpyrrolidone, 0.001 to 0.08. 0.08 wt percent of alkyl glycoside surfactant and 0.1 to 1.1 wt percent of glycerin derivative.

The inventor of the present invention has found through a great deal of research that when the polishing solution contains macromolecular polymer polyvinylpyrrolidone (PVP) and small molecular glycerol derivatives, the combination of the two can wet the surface of the silicon wafer to form a protective layer, thereby reducing the defects such as scratches in the polishing process and further reducing the roughness after polishing. The glycerol derivative also has a certain chelating effect on metal ions in the polishing solution, so that the haze value can be obviously reduced. In addition, PVP, glycerol derivative and alkyl glycoside surfactant are not easy to remain on the surface of the silicon wafer, so that the defects of the polished LPD are fewer. Therefore, after polishing the silicon wafer by using the polishing solution containing PVP, glycerol derivative and alkyl glycoside surfactant, the defects of the LPD, the roughness and the haze value are all obviously improved.

The content of the high purity abrasive in the chemical mechanical polishing liquid provided by the invention can be about 2 wt%, about 3 wt%, about 4 wt%, about 5 wt%, about 6 wt%, about 7 wt%, about 8 wt%, about 9 wt%, about 10 wt%, about 11 wt%, about 12 wt%, about 13 wt%, about 14 wt%, about 15 wt% or any mass percentage interval. In some preferred embodiments, the high purity abrasive may be present in an amount of 5 to 10 wt percent.

The content of polyvinylpyrrolidone in the chemical mechanical polishing solution provided by the invention can be about 0.01 wt%, about 0.05 wt%, about 0.1 wt%, about 0.15 wt%, about 0.2 wt%, about 0.25 wt%, about 0.3 wt%, about 0.35 wt%, about 0.4 wt%, about 0.45 wt%, about 0.5 wt% or any mass percentage interval. In some preferred embodiments, the polyvinylpyrrolidone may be present in an amount of 0.1 to 0.3 wt%.

The content of the alkyl glycoside surfactant in the chemical mechanical polishing liquid provided by the invention can be about 0.001 wt%, about 0.005 wt%, about 0.01 wt%, about 0.015 wt%, about 0.02 wt%, about 0.025 wt%, about 0.03 wt%, about 0.035 wt%, about 0.04 wt%, about 0.045 wt%, about 0.05 wt%, about 0.055 wt%, about 0.06 wt%, about 0.065 wt%, about 0.07 wt%, about 0.075 wt%, about 0.08 wt or any mass percent interval. In some preferred embodiments, the alkyl glycoside surfactant may be present in an amount of 0.01 to 0.05 wt%.

The content of the glycerol derivative in the chemical mechanical polishing solution provided by the invention can be about 0.1 wt%, about 0.2 wt%, about 0.3 wt%, about 0.4 wt%, about 0.5 wt%, about 0.6 wt%, about 0.7 wt%, about 0.8 wt%, about 0.9 wt%, about 1 wt% or any mass percentage interval. In some preferred embodiments, the glycerol derivative may be present in an amount of 0.2 to 0.7 wt%.

In some most preferred embodiments, the chemical mechanical polishing solution may further be an aqueous solution comprising: 5 to 10 wt percent of high-purity abrasive, 0.1 to 0.3 to wt percent of polyvinylpyrrolidone, 0.01 to 0.05 to wt percent of alkyl glycoside surfactant and 0.2 to 0.7 to wt percent of glycerin derivative.

In the chemical mechanical polishing solution provided by the invention, the high-purity abrasive can be polishing abrasive commonly used in the field, including but not limited to one or more of silicon dioxide, aluminum oxide and zirconium oxide. In some preferred embodiments, the high purity abrasive may be silica, which may be in the form of a silica sol having a metal ion content of less than 0.1 ppm, and a secondary particle size of from 30 to 120 nm, such as from 30 to 70 nm.

In the chemical mechanical polishing solution provided by the invention, the polyvinylpyrrolidone can be of a common model with an average molecular weight of 5000-1500000, including but not limited to one or more of PVP-K17, PVP-K30, PVP-K60 and PVP-K90. In some preferred embodiments, the polyvinylpyrrolidone may be of a common type having an average molecular weight of 5000 to 60000, such as one or both of PVP-K17 and PVP-K30.

In the chemical mechanical polishing solution provided by the invention, the alkyl glycoside surfactant can be of a common type, and the chain length of the alkyl glycoside surfactant can be 6-12 carbon atoms, including but not limited to one or more of APG-06, APG-08, APG-10 and APG-12. In some preferred embodiments, the alkyl glycoside surfactants may be those having a longer alkyl chain, such as those having an alkyl chain length of 10 to 12 carbon atoms, including but not limited to one or both of APG-10, APG-12.

In the chemical mechanical polishing solution provided by the invention, the glycerol derivative can be one or more of glycerol monoacetate, glycerol diacetate, glycerol triacetate, glycerol glucoside, glyceraldehyde diethyl acetal, glycerol monophosphate, glyceraldehyde monophosphate, glyceric acid monophosphate, glycerol monobutyrate, glycerol dibutyrate and glycerol tributyrate. In some preferred embodiments, the glycerol derivative may be one or more of glycerol glucoside, glycerol triphosphate, glycerol triacetate, glyceraldehyde diethyl acetal.

In the chemical mechanical polishing solution provided by the invention, the chemical mechanical polishing solution can also contain a pH regulator, and the pH value of the chemical mechanical polishing solution is regulated to be 10-11. The pH adjuster may be an amine or base type pH adjuster commonly known in the art including, but not limited to, one or more of potassium hydroxide, ammonium hydroxide, tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), piperazine. In some preferred embodiments, the pH adjuster may be ammonium hydroxide, which may be present in an amount of 0.1 to 0.5 wt%, for example, about 0.1 wt%, about 0.2 wt%, about 0.3 wt%, about 0.4 wt%, about 0.5 wt%, or any weight percent interval.

The chemical mechanical polishing solution provided by the invention can be prepared by a common preparation process in the field, wherein materials such as high-purity abrasive, PVP, surfactant, glycerol derivative, pH regulator and the like can be added into deionized water to reach the required content in any sequence.

In some preferred embodiments, the method for preparing the chemical mechanical polishing solution may be:

S1: adding the PVP to 20-40 wt% deionized water (i.e., 20-40 wt% or so of the total amount of deionized water required), for example, 30 wt% or so, to form a pre-dispersion solution; and

S2: and (3) adding the glycerol derivative, the surfactant and the pH regulator into the rest deionized water, and then sequentially adding the pre-dispersion liquid obtained in the step (S1) and the high-purity abrasive, and uniformly dispersing to obtain the high-purity abrasive.

A second aspect of the present invention provides the use of the chemical mechanical polishing solution according to any one of the preceding claims in chemical mechanical polishing of silicon wafers.

The silicon wafer of the invention can be a silicon wafer or a wafer with silicon as a substrate.

A third aspect of the present invention provides a chemical mechanical polishing method for a silicon wafer, which uses the chemical mechanical polishing solution according to any one of the foregoing technical solutions.

In the chemical mechanical polishing method, before the chemical mechanical polishing solution is used, deionized water with the volume of 20-40 times is used for dilution, and the pH value of the diluted chemical mechanical polishing solution is still 10-11.

The technical scheme provided by the invention has the following advantages:

(1) The chemical mechanical polishing solution provided by the invention can obtain the surface state of the polished and smooth silicon wafer through the synergistic effect of the components, and can effectively reduce the defects, roughness and haze value of the LPD.

(2) The polishing solution provided by the invention has the advantages of small component quantity, no need of a large amount of expensive reagents, good economy, simple preparation method and easy control of process, and can obviously reduce the polishing cost of the silicon wafer and improve the polishing efficiency, thereby having industrial practical value.

Detailed Description

The technical scheme of the invention is further described in detail below with reference to specific embodiments.

The sources of the raw materials or reagents used in the examples and comparative examples of the present invention are as follows (other raw materials or reagents are commercially available products unless otherwise specified):

the high purity abrasive was purchased from FUSO corporation, and the secondary particle size is shown in table 1;

polyvinylpyrrolidone purchased from acla Ding Pingtai;

Alkyl glycoside nonionic surfactants APG-06 and APG-08 are purchased from a source She Pingtai, APG-10 is purchased from a microphone platform, and APG-12 is purchased from Aba Ding Pingtai;

The AEO surface active of the fatty alcohol polyoxyethylene ether surfactant is purchased from Aba Ding Pingtai;

Glycerol derivatives were purchased from the mikrin platform.

The percentages used in the examples and comparative examples of the present invention are mass percentages unless otherwise specified.

Examples 1 to 9

The components and contents of the polishing liquid formulations used in examples 1 to 9 are shown in Table 1, and each component is prepared according to the content of pure matters and comprises the following steps:

Firstly, adding polymer PVP into 30 wt percent of deionized water (the required deionized water amount is calculated according to the table 1), and stirring and dispersing into an aqueous solution for later use; then adding glycerol derivative, surfactant and pH regulator into the rest deionized water, stirring and dispersing, adding pre-dispersed PVP solution, continuing stirring and dispersing, finally adding the required amount of silica sol, and stirring and dispersing uniformly to obtain the fine polishing liquid.

Table 1 fine polishing liquid formulations of examples 1 to 9

Comparative example 1

Referring to the formulation of example 1, PVP K30 was not added, the other components were unchanged and the pH was 10.81.

Comparative example 2

With reference to the formulation of example 1, no glycerol glucoside was added, the other components were unchanged and the pH was 10.92.

Comparative example 3

With reference to the formulation of example 2, no glyceraldehyde diethyl acetal was added, the other components were unchanged and the pH was 10.83.

Comparative example 4

With reference to the formulation of example 6, the surfactant was replaced with AEO-9, the other components were unchanged, and the pH was 10.64.

Polishing of silicon wafers was performed using the polishing solutions of the above examples and comparative examples, and the properties of the polished wafers were tested, and the polishing solutions were diluted with 30 volumes of deionized water before use.

The specific polishing conditions were as follows: the polishing machine table is 12' Ebara F-REX300X, the polishing pad is Politex, the polishing pressure is 2 psi, the rotation speed of the polishing disk and the polishing head is 93/87 rpm, the flow rate of the polishing liquid is 300 mL/min, and the polishing time is 2 min.

Haze test: KLA Surfscan SP5 was used.

LPD test: using KLA Surfscan SP5, the number of LPDs with a gauge greater than 40nm was used as a measure of defect conditions, with the other examples and comparative examples being based on comparative example 1.

Roughness test: sensofar 3D copolymerization Jiao Baiguang interferometry measures roughness in the range of 330×287 [ mu ] m, and obtains Sq value as a measure of roughness.

The test results are shown in table 2:

table 2 test results of examples and comparative examples

From the comparison of comparative example 1 and example 1, it is apparent that PVP, when added, can act synergistically with glycerol derivatives and surfactants to adsorb on the surface of silicon wafers and form a hydrophilic protective layer, thereby effectively reducing LPD defects, roughness and haze.

As is clear from examples 1 and 2,2 and 3, when PVP is contained in the polishing liquid but no glycerin derivative is contained, the desired polishing effect cannot be obtained, and after the glycerin derivative is added, it can be adsorbed on the wafer surface together with PVP to form a hydrophilic protective layer, and the glycerin derivative has a certain complexing ability for metal ions, thereby also reducing wafer micro-corrosion due to metal ions.

As can be seen from a comparison of examples 7 and 8 with examples 1-6, there is a certain increase in LPD defects and roughness as the average molecular weight of PVP increases. As can be seen from a comparison of example 9 and example 6, the polishing solution using APG-12 can obtain fewer LPD defects compared with APG-06, because the APG-12 has longer carbon chain, and is easy to react with particles in the polishing process, and the compatibility of the particles in water is enhanced after the particles are adsorbed on the surface of the particles, so that the particles are not easy to stain the surface of a wafer.

As is clear from a comparison of comparative example 4 and example 6, when PVP and glycerol derivatives are contained in the polishing solution, the APG series surfactant is more suitable, so that excellent LPD performance can be achieved, and other commonly used surfactants (such as AEO-9) cannot achieve corresponding effects.

Unless otherwise defined, all terms used herein are intended to have the meanings commonly understood by those skilled in the art.

The described embodiments of the present invention are intended to be illustrative only and not to limit the scope of the invention, and various other alternatives, modifications, and improvements may be made by those skilled in the art within the scope of the invention, and therefore the invention is not limited to the above embodiments but only by the claims.

Claims (12)

1. The chemical mechanical polishing liquid is characterized by comprising the following components in aqueous solution: 2 to 15. 15 wt percent of high-purity abrasive, 0.01 to 0.5. 0.5 wt percent of polyvinylpyrrolidone, 0.001 to 0.08. 0.08 wt percent of alkyl glycoside surfactant and 0.1 to 1. 1 wt percent of glycerin derivative.

2. The chemical mechanical polishing liquid according to claim 1, wherein the chemical mechanical polishing liquid is an aqueous solution comprising: 5 to 10wt percent of high-purity abrasive, 0.1 to 0.3 to wt percent of polyvinylpyrrolidone, 0.01 to 0.05 to wt percent of alkyl glycoside surfactant and 0.2 to 0.7 to wt percent of glycerin derivative.

3. The chemical mechanical polishing liquid according to claim 1 or 2, wherein the high-purity abrasive is one or more of silica, alumina and zirconia, wherein the content of metal ions is less than 0.1 ppm, and the secondary particle size is 30-120 nm.

4. The chemical mechanical polishing liquid according to claim 1 or 2, wherein the average molecular weight of the polyvinylpyrrolidone is 5000 to 1500000.

5. The chemical mechanical polishing liquid according to claim 4, wherein the polyvinylpyrrolidone is one or more of PVP-K17, PVP-K30, PVP-K60, PVP-K90.

6. The chemical mechanical polishing liquid according to claim 1 or 2, wherein the alkyl chain length of the alkyl glycoside surfactant is 6 to 12 carbon atoms.

7. The chemical mechanical polishing liquid according to claim 6, wherein the alkyl glycoside surfactant is one or more of APG-06, APG-08, APG-10, APG-12.

8. The chemical mechanical polishing liquid according to claim 1 or 2, wherein the glycerol derivative is one or more of glycerol monoacetate, glycerol diacetate, glycerol triacetate, glycerol glucoside, glyceraldehyde diethyl acetal, glycerol monophosphate, glyceraldehyde monophosphate, glyceric acid monophosphate, glycerol monobutyrate, glycerol dibutyrate, and glycerol tributyrate.

9. The chemical mechanical polishing liquid according to claim 1 or 2, further comprising a pH adjuster, wherein the pH of the chemical mechanical polishing liquid is adjusted to 10 to 11; the pH regulator is one or more of potassium hydroxide, ammonium hydroxide, tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide and piperazine.

10. Use of the chemical mechanical polishing solution according to any one of claims 1 to 9 for chemical mechanical polishing of silicon wafers.

11. A chemical mechanical polishing method of a silicon wafer, characterized in that the chemical mechanical polishing method uses the chemical mechanical polishing liquid according to any one of claims 1 to 9.

12. The chemical mechanical polishing method as recited in claim 11, wherein the chemical mechanical polishing solution is diluted with 20 to 40 volumes of deionized water before use, and the pH of the diluted chemical mechanical polishing solution is 10 to 11.