CN116948533A - Coarse grinding fluid for silicon carbide wafer processing and preparation method thereof - Google Patents

Abstract

The invention relates to a coarse grinding fluid for processing silicon carbide wafers and a preparation method thereof, wherein the coarse grinding fluid comprises a solution A and a solution B; the solution A comprises the following raw materials in percentage by mass: 5-15% of alumina; 0.1-5% of dispersing agent; 0.5-10% of oxidant; 0.001-1% of bactericide; the balance being water; the solution B comprises the following raw materials in percentage by mass: 0.1-5% of promoter; 0.001-1% of bactericide; the balance being water. The preparation method comprises the steps of firstly preparing a solution A and a solution B, and then mixing the solution A and the solution B to obtain a coarse grinding liquid. The coarse grinding liquid provided by the invention has the advantages of high removal rate, good surface polishing effect and capability of being recycled.

Description

Coarse grinding fluid for silicon carbide wafer processing and preparation method thereof

Technical Field

The invention relates to the technical field of chemical mechanical polishing, in particular to a coarse grinding fluid for silicon carbide wafer processing and a preparation method thereof.

Background

At present, more than 95% of semiconductor elements in the market mainly adopt first-generation semiconductor material silicon as a basic functional material. With the rise of 5G applications, silicon-based semiconductor materials are limited by their physical properties, which are difficult to further improve in performance. Based on this, third generation semiconductor materials typified by gallium nitride, silicon carbide, and the like are attracting attention.

The processing technology of the silicon carbide substrate is an important technological base for manufacturing semiconductor devices, and the surface processing quality and precision of the silicon carbide wafer directly influence the quality and device performance of the epitaxial thin film. Therefore, in the application of silicon carbide wafers, the surface of the silicon carbide wafer is required to be ultra-smooth, defect-free, and damage-free, and to have a surface roughness of nanometer order or less. However, silicon carbide crystals have the characteristics of high hardness, high brittleness, good wear resistance, and extremely stable chemical properties, thus making processing of silicon carbide wafers very difficult. In general, the ultra-precision machining process of silicon carbide wafers generally comprises the following stages in order: directional cutting, grinding (including coarse grinding and fine grinding), polishing (typically mechanical polishing), and ultra-precise polishing (typically chemical mechanical polishing). The silicon carbide wafer rough grinding liquid adopted in the rough grinding stage is generally low in removal rate, the content of metal ions in the rough grinding liquid is high, the roughness after rough grinding is more than 3nm, and the surface of the wafer contains more scratches with larger size.

Therefore, it is important to provide a rough grinding fluid for silicon carbide wafer processing with a high grinding rate and removal amount.

Disclosure of Invention

Aiming at the problems, the invention aims to provide the rough grinding liquid for processing the silicon carbide wafer and the preparation method thereof.

In order to achieve the aim of the invention, the invention adopts the following technical scheme:

in a first aspect, the present invention provides a rough grinding fluid for silicon carbide wafer processing, the rough grinding fluid comprising a solution a and a solution B;

the solution A comprises the following raw materials in percentage by mass: 5-15% of alumina; 0.1-5% of dispersing agent; 0.5-10% of oxidant; 0.001-1% of bactericide; the balance being water;

the solution B comprises the following raw materials in percentage by mass: 0.1-5% of promoter; 0.001-1% of bactericide; the balance being water.

In the coarse grinding liquid provided by the invention, the solution A and the solution B are obtained by adopting the alumina, the dispersing agent, the oxidant, the accelerator and the bactericide, and the impurity removal amount can be improved by the cooperation of the solution A and the solution B, so that the coarse grinding liquid has a good surface polishing effect and can be recycled.

Preferably, the alumina has an average particle size of 100-800nm, for example, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, 550nm, 600nm, 650nm, 700nm, 750nm or 800nm, but not limited to the recited values, and other non-recited values within the range of values are equally applicable.

Preferably, the shape of the alumina is spherical.

Preferably, the alumina has a mohs hardness of 9 to 9.2, which may be, for example, 9, 9.1 or 9.2, but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.

According to the invention, the wear resistance of the rough grinding liquid can be further improved and the removal effect can be improved by specifically selecting the average particle size and the Mohs hardness of the alumina to be in a specific range and controlling the morphology of the alumina to be spherical.

Preferably, the dispersant comprises PAAS and/or STA-1210, i.e. sodium polyacrylate and/or an acidic group containing interpolymer solution.

Preferably, the oxidizing agent comprises potassium permanganate and/or hydrogen peroxide.

In the present invention, the polishing rate can be further improved by adding an oxidizing agent and controlling the kind of the oxidizing agent.

Preferably, the hydrogen peroxide has a mass concentration of 2-4%, for example, 2%, 2.2%, 2.4%, 2.6%, 2.8%, 3%, 3.2%, 3.4%, 3.6%, 3.8% or 4%, but not limited to the recited values, and other non-recited values within the range of values are equally applicable.

Preferably, the promoter comprises manganese dioxide.

The manganese dioxide preferably has an average particle size of 1 to 2. Mu.m, for example, 1 μm, 1.2 μm, 1.4 μm, 1.6 μm, 1.8 μm or 2. Mu.m, but is not limited to the values recited, and other values not recited in the numerical range are equally applicable.

In the invention, the effect of adding manganese dioxide is to accelerate the reaction rate.

Preferably, the germicides include pinacol and/or 1, 2-benzisothiazolin-3-one.

In a second aspect, the present invention provides a method for preparing a rough grinding fluid for processing a silicon carbide wafer according to the first aspect of the present invention, the method comprising the steps of:

(1) Mixing aluminum oxide, a dispersing agent, an oxidant, a bactericide and water to obtain a solution A;

(2) Mixing the accelerator, the bactericide and water to obtain a solution B;

(3) Mixing the solution A and the solution B to obtain the coarse grinding fluid.

According to the invention, the solution A and the solution B are prepared first and then mixed, so that the reduction of the effect of the rough grinding liquid caused by the reaction of the oxidant and the accelerator can be avoided, and the effects of improving the removal effect and the grinding rate of the rough grinding liquid are achieved.

Preferably, the mixing in step (1) is followed by a first pH adjustment treatment and a first filtration treatment in sequence.

Preferably, the regulator used in the first pH adjustment treatment comprises an acid solution.

Preferably, the acid solution used for the first pH adjustment treatment comprises nitric acid and/or sulfuric acid.

Preferably, the end point pH of the first pH adjustment treatment is 3-5, which may be, for example, 3, 3.2, 3.4, 3.6, 3.8, 4, 4.2, 4.4, 4.6, 4.8 or 5, but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.

Preferably, the first filtering process includes a primary filtering and a secondary filtering performed sequentially.

Preferably, the first filtering process has a precision of 1-5 μm, for example, 1 μm, 2 μm, 3 μm, 4 μm or 5 μm, but not limited to the recited values, and other values not recited in the range of values are equally applicable.

The secondary filtration in the first filtration treatment preferably has a precision of 0.1 to 0.5 μm, for example, 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm or 0.5 μm, but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.

Preferably, the mixing is followed by a second pH adjustment treatment and a second filtration treatment in sequence.

Preferably, the regulator used in the second pH adjustment treatment comprises an acid solution.

Preferably, the acid solution used for the second pH adjustment treatment comprises nitric acid and/or sulfuric acid.

Preferably, the second pH adjustment treatment has an end pH of 3 to 5, which may be, for example, 3, 3.2, 3.4, 3.6, 3.8, 4, 4.2, 4.4, 4.6, 4.8 or 5, but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.

In the invention, the pH value of the end point is preferably controlled in a specific range, so that the removal effect and the removal rate can be further improved.

Preferably, the second filtering process includes a primary filtering and a secondary filtering performed sequentially.

Preferably, the accuracy of the first stage filtering in the second filtering process is 1-5 μm, for example, 1 μm, 2 μm, 3 μm, 4 μm or 5 μm, but not limited to the recited values, and other values not recited in the range of values are equally applicable.

Preferably, the second filtering process has a secondary filtering accuracy of 0.1-0.5 μm, for example, 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm or 0.5 μm, but not limited to the recited values, and other non-recited values within the range of values are equally applicable.

Preferably, the mass ratio of solution A to solution B in the mixing in step (3) is 1 (3-7), and may be, for example, 1:3, 1:4, 1:5, 1:6 or 1:7, but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.

In the invention, the mass ratio of the solution A to the solution B is preferably controlled within a specific range, so that the removal effect and the grinding rate of the rough grinding liquid can be further improved.

As a preferred technical scheme of the invention, the preparation method comprises the following steps:

(1) Mixing aluminum oxide, a dispersing agent, an oxidant, a bactericide and water, then adopting acid liquor to carry out first pH value adjustment treatment until the end point pH value is 3-5, then carrying out first-stage filtration with the precision of 1-5 mu m, and then carrying out second-stage filtration with the precision of 0.1-0.5 mu m to obtain solution A;

(2) Mixing the accelerator, the bactericide and the water, then adopting acid liquor to carry out second pH value adjustment treatment until the end point pH value is 3-5, then carrying out primary filtration with the precision of 1-5 mu m, and then carrying out secondary filtration with the precision of 0.1-0.5 mu m to obtain solution B;

(3) Mixing the solution A and the solution B according to the mass ratio of 1 (3-7) to obtain the coarse grinding liquid.

Compared with the prior art, the invention has the following beneficial effects:

the coarse grinding liquid provided by the invention has high removal rate and good surface polishing effect, can reduce the roughness of a silicon surface to below 0.045nm, reduce the roughness of a carbon surface to below 0.097nm, and can reduce the roughness of the silicon surface to below 0.039nm and reduce the roughness of the carbon surface to below 0.084nm under a better condition; the removal rate can reach more than 1.56 mu m/h, and can reach more than 1.82 mu m/h under the better condition, and the device can be recycled.

Detailed Description

The technical scheme of the invention is further described by the following specific embodiments. It will be apparent to those skilled in the art that the examples are merely to aid in understanding the invention and are not to be construed as a specific limitation thereof.

Example 1

The embodiment provides a coarse grinding fluid for processing a silicon carbide wafer, wherein the coarse grinding fluid comprises a solution A and a solution B;

the solution A comprises the following raw materials in percentage by mass: alumina 5%; PAAS 0.5%; potassium permanganate 0.1%;1, 2-benzisothiazolin-3-one 0.01%; the balance being water;

the solution B comprises the following raw materials in percentage by mass: manganese dioxide 0.2%;1, 2-benzisothiazolin-3-one 0.01%; the balance being water.

The embodiment also provides a preparation method of the rough grinding liquid for processing the silicon carbide wafer, which comprises the following steps:

(1) Mixing aluminum oxide, PAAS, potassium permanganate, 1, 2-benzisothiazolin-3-one and water, then adopting nitric acid to carry out first pH value adjustment treatment until the end point pH value is 4, then carrying out primary filtration with the precision of 2 mu m, and then carrying out secondary filtration with the precision of 0.2 mu m to obtain a solution A;

(2) Mixing manganese dioxide, 1, 2-benzisothiazolin-3-one and water, then adopting nitric acid to carry out second pH value adjustment treatment until the end point pH value is 4, then carrying out primary filtration with the precision of 2 mu m, and then carrying out secondary filtration with the precision of 0.2 mu m to obtain a solution B;

(3) Mixing the solution A and the solution B according to the mass ratio of 1:5 to obtain the coarse grinding liquid.

Example 2

The embodiment provides a coarse grinding fluid for processing a silicon carbide wafer, wherein the coarse grinding fluid comprises a solution A and a solution B;

the solution A comprises the following raw materials in percentage by mass: 10% of alumina; STA-1210 2%; 5% of potassium permanganate; 0.5% of 1, 2-benzisothiazolin-3-one; the balance being water;

the solution B comprises the following raw materials in percentage by mass: 2% of manganese dioxide; 0.5% of 1, 2-benzisothiazolin-3-one; the balance being water.

The embodiment also provides a preparation method of the rough grinding liquid for processing the silicon carbide wafer, which comprises the following steps:

(1) Mixing aluminum oxide, STA-1210, potassium permanganate, 1, 2-benzisothiazolin-3-one and water, then adopting sulfuric acid to carry out first pH value adjustment treatment until the end point pH value is 3, then carrying out primary filtration with the precision of 1 mu m, and then carrying out secondary filtration with the precision of 0.5 mu m to obtain a solution A;

(2) Mixing manganese dioxide, 1, 2-benzisothiazolin-3-one and water, then adopting sulfuric acid to carry out second pH value adjustment treatment until the end point pH value is 3, then carrying out primary filtration with the precision of 1 mu m, and then carrying out secondary filtration with the precision of 0.5 mu m to obtain a solution B;

(3) Mixing the solution A and the solution B according to the mass ratio of 1:3 to obtain the coarse grinding liquid.

Example 3

The embodiment provides a coarse grinding fluid for processing a silicon carbide wafer, wherein the coarse grinding fluid comprises a solution A and a solution B;

the solution A comprises the following raw materials in percentage by mass: 15% of alumina; PAAS 5%; 10% of potassium permanganate; 1, 2-benzisothiazolin-3-one 1%; the balance being water;

the solution B comprises the following raw materials in percentage by mass: manganese dioxide 5%;1, 2-benzisothiazolin-3-one 1%; the balance being water.

The embodiment also provides a preparation method of the rough grinding liquid for processing the silicon carbide wafer, which comprises the following steps:

(1) Mixing aluminum oxide, PAAS, potassium permanganate, 1, 2-benzisothiazolin-3-one and water, then adopting nitric acid to carry out first pH value adjustment treatment until the end point pH value is 5, then carrying out first-stage filtration with the precision of 5 mu m, and then carrying out second-stage filtration with the precision of 0.1 mu m to obtain a solution A;

(2) Mixing manganese dioxide, 1, 2-benzisothiazolin-3-one and water, then adopting nitric acid to carry out second pH value adjustment treatment until the end point pH value is 5, then carrying out primary filtration with the precision of 5 mu m, and then carrying out secondary filtration with the precision of 0.1 mu m to obtain a solution B;

(3) And mixing the solution A and the solution B according to the mass ratio of 1:7 to obtain the coarse grinding liquid.

Example 4

This example provides a method of preparing a rough grinding fluid for silicon carbide wafer processing, which differs from example 1 only in that the mass ratio of solution a to solution B is 1:1.

Example 5

This example provides a method of preparing a rough grinding fluid for silicon carbide wafer processing, which differs from example 1 only in that the mass ratio of solution a to solution B is 1:9.

Comparative example 1

This comparative example provides a rough grinding fluid for silicon carbide wafer processing, which differs from example 1 only in that the mass percentage of alumina in solution a is 2%.

Comparative example 2

This comparative example provides a rough grinding fluid for silicon carbide wafer processing differing from example 1 only in that the mass percent of alumina in solution a is 20%.

Comparative example 3

This comparative example provides a rough grinding fluid for silicon carbide wafer processing, which differs from example 1 only in that the mass percentage of potassium permanganate in solution a is 0.1%.

Comparative example 4

This comparative example provides a rough grinding fluid for silicon carbide wafer processing, which differs from example 1 only in that the mass percentage of potassium permanganate in solution a is 15%.

Comparative example 5

This comparative example provides a method for preparing a rough grinding liquid for silicon carbide wafer processing, which differs from example 1 only in that only step (1) is performed, i.e., the rough grinding liquid is only solution a.

Comparative example 6

This comparative example provides a method for preparing a rough grinding liquid for silicon carbide wafer processing, which differs from example 1 only in that only step (2) is performed, i.e., the rough grinding liquid is only solution B.

The crude grinding fluids in examples 1-5 and comparative examples 1-6 were subjected to a pressure of 400g/cm ² The silicon carbide wafer was subjected to double-sided rough polishing at a rotation speed of 63r/min under the condition that the polishing pad was a non-woven polishing pad, the roughness of the carbon surface and the silicon surface after polishing was detected by a surface roughness method, the results are shown in Table 1, and the removal rate of the polishing liquid was detected by a film degree method, and the results are shown in Table 1.

TABLE 1

In table 1, "-" indicates that polishing was not performed, and no data was found.

(1) From the data of examples 1-5, it can be seen that the rough grinding liquid provided by the invention can reduce the roughness of the silicon surface to below 0.045nm, the roughness of the carbon surface to below 0.097nm, the roughness of the silicon surface to below 0.039nm under the preferable condition, and the roughness of the carbon surface to below 0.084 nm; the removal rate can reach more than 1.56 mu m/h, and the removal rate can reach more than 1.82 mu m/h under the better condition.

(2) As can be seen from a combination of the data of examples 1 and examples 4 to 5, the difference between examples 4 to 5 and example 1 is that the mass ratio of the solution a and the solution B is not within the preferred range of the present invention, and the roughness of both the silicon surface and the carbon surface in example 1 is lower than that in examples 4 to 5 and the removal rate is higher than that in examples 4 to 5, whereby it can be seen that the preferred control of the mass ratio of the solution a and the solution B of the present invention can further enhance the polishing effect and enhance the removal rate.

(3) As can be seen from a combination of the data of comparative examples 1, 1-2 and 3-4, comparative examples 1-2 differ from example 1 only in that the mass percentage of alumina is not within the preferred range of the present invention, comparative examples 3-4 differ from example 1 only in that the mass percentage of potassium permanganate is not within the preferred range of the present invention, the removal rate in example 1 is significantly higher than that of comparative examples 1, 3, 4, and the roughness in example 1 is significantly lower than that of comparative example 2, and thus it can be seen that the present invention preferably controls the mass percentage of alumina and the mass percentage of potassium permanganate to further enhance the grinding effect and removal rate.

(4) As can be seen from the data of comparative examples 1 and comparative examples 5 to 6, comparative examples 5 to 6 differ from example 1 only in that only solution a or solution B, respectively, was used, the removal rate in example 1 was significantly higher than that in comparative example 5, and comparative example 6 was not able to be ground, and thus, it can be seen that the present invention can achieve the effects of reducing the surface roughness of silicon and carbon surfaces and improving the removal rate by obtaining a rough grinding liquid by using solution a and solution B.

In conclusion, the coarse grinding liquid provided by the invention has the advantages of high removal rate, good surface polishing effect and capability of being recycled.

The applicant declares that the above is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be apparent to those skilled in the art that any changes or substitutions that are easily conceivable within the technical scope of the present invention disclosed by the present invention fall within the scope of the present invention and the disclosure.

Claims (10)

1. A coarse grinding fluid for processing a silicon carbide wafer, which is characterized by comprising a solution A and a solution B;

the solution A comprises the following raw materials in percentage by mass: 5-15% of alumina; 0.1-5% of dispersing agent; 0.5-10% of oxidant; 0.001-1% of bactericide; the balance being water;

the solution B comprises the following raw materials in percentage by mass: 0.1-5% of promoter; 0.001-1% of bactericide; the balance being water.

2. The coarse grinding fluid of claim 1, wherein the alumina has an average particle size of 100-800nm;

preferably, the shape of the alumina is spherical;

preferably, the alumina has a mohs hardness of 9 to 9.2.

3. The kibble of claim 1 or 2, wherein the dispersant comprises PAAS and/or STA-1210.

4. A coarse grinding fluid according to any one of claims 1-3, wherein the oxidizing agent comprises potassium permanganate and/or hydrogen peroxide;

preferably, the mass concentration of the hydrogen peroxide is 2-4%.

5. The coarse grinding fluid of any one of claims 1-4 wherein the promoter comprises manganese dioxide;

preferably, the manganese dioxide has an average particle size of 1-2 μm.

6. The coarse grinding fluid of any one of claims 1-5 wherein the germicide comprises pinocembrane and/or 1, 2-benzisothiazolin-3-one.

7. A method for preparing a rough grinding liquid for silicon carbide wafer processing according to any one of claims 1 to 6, comprising the steps of:

(1) Mixing aluminum oxide, a dispersing agent, an oxidant, a bactericide and water to obtain a solution A;

(2) Mixing the accelerator, the bactericide and water to obtain a solution B;

(3) Mixing the solution A and the solution B to obtain the coarse grinding fluid;

the step (1) and the step (2) have no sequence relation.

8. The method according to claim 7, wherein the mixing in step (1) is followed by a first pH adjustment treatment and a first filtration treatment in sequence;

preferably, the regulator used in the first pH adjustment treatment comprises an acid solution;

preferably, the acid solution used for the first pH value adjusting treatment comprises nitric acid and/or sulfuric acid;

preferably, the end point pH of the first pH adjustment treatment is 3-5;

preferably, the first filtering treatment comprises a primary filtering and a secondary filtering which are sequentially carried out;

preferably, the first stage of the first filtering process has a precision of 1-5 μm;

preferably, the secondary filtration in the first filtration treatment has a precision of 0.1 to 0.5 μm.

9. The method according to claim 7 or 8, wherein the mixing in step (2) is followed by a second pH adjustment treatment and a second filtration treatment in that order;

preferably, the regulator used in the second pH adjustment treatment comprises an acid solution;

preferably, the acid solution used for the second pH adjustment treatment comprises nitric acid and/or sulfuric acid;

preferably, the end point pH of the second pH adjustment treatment is 3-5;

preferably, the second filtering treatment comprises a primary filtering and a secondary filtering which are sequentially carried out;

preferably, the accuracy of the first stage filtration in the second filtration treatment is 1-5 μm;

preferably, the second filtering process has a secondary filtering precision of 0.1-0.5 μm;

preferably, the mass ratio of the solution A to the solution B in the mixing in the step (3) is 1 (3-7).

10. A method of preparing a coarse grinding fluid according to any one of claims 7-9, characterized in that the method comprises the steps of:

(1) Mixing aluminum oxide, a dispersing agent, an oxidant, a bactericide and water, then adopting acid liquor to carry out first pH value adjustment treatment until the end point pH value is 3-5, then carrying out first-stage filtration with the precision of 1-5 mu m, and then carrying out second-stage filtration with the precision of 0.1-0.5 mu m to obtain solution A;

(2) Mixing the accelerator, the bactericide and the water, then adopting acid liquor to carry out second pH value adjustment treatment until the end point pH value is 3-5, then carrying out primary filtration with the precision of 1-5 mu m, and then carrying out secondary filtration with the precision of 0.1-0.5 mu m to obtain solution B;

(3) Mixing the solution A and the solution B according to the mass ratio of 1 (3-7) to obtain the coarse grinding liquid.