阅读说明：本技术 一种碳化硅专用钻石切割液的配置方法 (Preparation method of diamond cutting fluid special for silicon carbide ) 是由 陈辉 王升 李有群 贺贤汉 于 2021-09-30 设计创作，主要内容包括：本发明公开了一种碳化硅专用钻石切割液的配置方法,通过将碳化硅晶体切割常规使用的油性砂浆替换成亲水性砂浆,同时加入一定比例的分散剂,保证砂浆具有良好的分散效果,在不影响砂浆的切割效果的前提下,又能提高切割后晶片的清洗效果。此砂浆无需使用煤油等易燃易爆的有机溶剂来清洗,可通过使用清水或低浓度碱液轻易洗净,可有效降低环评等级,非常适用于批量化的碳化硅衬底片生产使用。(The invention discloses a preparation method of a diamond cutting fluid special for silicon carbide, which is characterized in that oily mortar conventionally used for cutting silicon carbide crystals is replaced by hydrophilic mortar, and a certain proportion of dispersing agent is added, so that the mortar has a good dispersing effect, and the cleaning effect of cut wafers can be improved on the premise of not influencing the cutting effect of the mortar. The mortar is not required to be cleaned by flammable and explosive organic solvents such as kerosene and the like, can be easily cleaned by using clear water or low-concentration alkali liquor, can effectively reduce the environmental evaluation grade, and is very suitable for the production and use of batch silicon carbide substrate pieces.)

1. A preparation method of diamond cutting fluid special for silicon carbide is characterized by comprising the following steps: the preparation method comprises the following steps:

(1) pouring the required amount of dihydric alcohol into a mixing barrel;

(2) taking required amount of polyglycol in proportion and pouring the polyglycol into a mixing barrel;

(3) opening a mixing barrel to perform a stirring function;

(4) weighing a required amount of dispersing agent, and slowly and completely pouring the dispersing agent into a mixing barrel from a feeding port at the top of the mixing barrel;

(5) stirring for more than 15min to ensure that the dispersing agent is uniformly mixed in the mixed solution;

(6) weighing diamond micropowder with required amount, and slowly and completely pouring the diamond micropowder into a mixing barrel from a feeding port at the top of the mixing barrel;

(7) mixing for 24h to ensure that the diamond micro powder is uniformly dispersed in the cutting fluid and ensure the subsequent cutting quality;

(8) and pouring the mixed mortar into a material barrel of a cutting machine for cutting.

2. The method for preparing a diamond cutting fluid special for silicon carbide according to claim 1, wherein the diamond cutting fluid comprises: the grain diameter of the diamond micro powder is 4-9 um, and the normal distribution of the grain diameter is as follows: 4um particles account for 2.4%, 5um particles for 14.1%, 6um particles for 36.2%, 7um particles for 43.5%, 9um particles for 3.8%.

3. The method for preparing a diamond cutting fluid special for silicon carbide according to claim 1, wherein the diamond cutting fluid comprises: the concentration of the diamond micro powder is 12 to 18 percent of the weight percentage of the mortar.

4. The method for preparing a diamond cutting fluid special for silicon carbide according to claim 1, wherein the diamond cutting fluid comprises: the organic dispersant is polyacrylamide.

5. The method for preparing a diamond cutting fluid special for silicon carbide according to claim 1, wherein the diamond cutting fluid comprises: the additive ratio of the dihydric alcohol is 60-70%, the additive ratio of the polyglycol is 20-30%, the additive ratio of the polyacrylamide emulsion is 8-12%, and the concentration of the drilling powder is 12-18% of the weight percentage of the mortar.

Technical Field

The invention relates to a preparation method of diamond cutting fluid special for silicon carbide.

Background

The silicon carbide is taken as a representative of third-generation semiconductors, has the characteristics of large forbidden band width, high breakdown electric field, high saturated electron drift velocity, large heat conductivity and the like, and can be applied to a high-voltage environment of more than 1200 volts, so that the silicon carbide has obvious advantages in a severe environment; meanwhile, the SiC crystal is an ideal substrate material of GaN-based devices, such as LEDs and LDs, because the SiC crystal has a high matching lattice constant and thermal expansion coefficient with the epitaxial layer material GaN and good thermal conductivity. Therefore, SiC crystal materials have become indispensable substrate materials in the field of semiconductor lighting technology. Silicon carbide and silicon carbide-based semiconductor materials have become hot of research in various countries around the world.

The silicon carbide crystal is applied to a device to be processed into a wafer with a certain size, and the basic process comprises the steps of crystal growth, ingot detection, ingot shaping, slicing, marking, grinding, chamfering, polishing, CMP, cleaning and the like. Because the hardness of the silicon carbide crystal is high, great difficulty is brought to crystal processing, and the cutting of the SiC crystal bar into wafers with small warpage, uniform thickness and low cutting loss is very important for subsequent grinding and polishing. Compared with the traditional inner circle and outer circle cutting, the multi-line cutting has the advantages of high cutting speed, high processing precision, high efficiency, long service life and the like, and is widely applied to the high-efficiency cutting of the silicon carbide wafer.

Because of the high hardness of silicon carbide crystals, only multi-line cutting can be carried out by using diamond powder mortar at present. Moreover, in order to ensure the cutting quality, the mortar needs to have good suspension property so as to ensure the stability of the concentration of the mortar in the whole cutting process. Therefore, oily diamond mortar is currently used in the industry for cutting silicon carbide crystals. However, the oil-based mortar has high viscosity and strong adhesiveness, is not easy to clean, and needs to be cleaned by kerosene. Kerosene belongs to flammable and explosive chemicals, has high environmental evaluation requirements, is not suitable for mass storage, and cannot be discharged at will.

Disclosure of Invention

The invention aims to provide a preparation method of a diamond cutting fluid special for silicon carbide, which aims to solve the problems in the background technology.

In order to achieve the purpose, the invention provides the following technical scheme:

a preparation method of diamond cutting fluid special for silicon carbide comprises the following manufacturing steps:

(1) pouring the required amount of dihydric alcohol into a mixing barrel;

(2) taking required amount of polyglycol in proportion and pouring the polyglycol into a mixing barrel;

(3) opening a mixing barrel to perform a stirring function;

(4) weighing a required amount of dispersing agent, and slowly and completely pouring the dispersing agent into a mixing barrel from a feeding port at the top of the mixing barrel;

(5) stirring for more than 15min to ensure that the dispersing agent is uniformly mixed in the mixed solution;

(6) weighing diamond micropowder with required amount, and slowly and completely pouring the diamond micropowder into a mixing barrel from a feeding port at the top of the mixing barrel;

(7) mixing for 24h to ensure that the diamond micro powder is uniformly dispersed in the cutting fluid and ensure the subsequent cutting quality;

(8) and pouring the mixed mortar into a material barrel of a cutting machine for cutting.

Preferably, the particle size of the diamond micro powder is 4-9 um, and the normal distribution of the particle size is as follows: 4um particles account for 2.4%, 5um particles for 14.1%, 6um particles for 36.2%, 7um particles for 43.5%, 9um particles for 3.8%.

Preferably, the concentration of the diamond micropowder is 12-18% of the weight percentage of the mortar.

Preferably, the organic dispersant is polyacrylamide.

Preferably, the addition ratio of the dihydric alcohol is 60-70%, the addition ratio of the polyglycol is 20-30%, the addition ratio of the polyacrylamide emulsion is 8-12%, and the concentration of the drilling powder is 12-18% of the weight percentage of the mortar.

Compared with the prior art, the invention has the beneficial effects that: according to the preparation method provided by the invention, the mortar has good suspension property and uniformly dispersed particles, the cutting effect of the silicon carbide crystal can be ensured, the TTV of the cut piece is good, the warpage is small, meanwhile, the attachment of the cutting liquid on the surface of the wafer can be cleaned by using clear water or low-concentration alkali liquor, and the cleaning difficulty of the cut wafer is effectively reduced. The invention has simple operation, low cost and good effect.

Drawings

FIG. 1 is a particle size distribution diagram of the diamond fine powder of the present invention;

FIG. 2 is a table showing a particle size distribution of the diamond fine powder of the present invention;

FIG. 3 shows a method for preparing the diamond cutting fluid for silicon carbide according to the present invention.

In the figure: 1. a mixing barrel; 2. a variable speed motor; 3. stirring blades; 4. a funnel; 5. a liquid discharging port.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

A preparation method of diamond cutting fluid special for silicon carbide comprises the following manufacturing steps:

(1) pouring the required amount of dihydric alcohol into a mixing barrel;

(2) taking required amount of polyglycol in proportion and pouring the polyglycol into a mixing barrel;

(3) opening a mixing barrel to perform a stirring function;

(4) weighing a required amount of dispersing agent, and slowly and completely pouring the dispersing agent into a mixing barrel from a feeding port at the top of the mixing barrel;

(5) stirring for more than 15min to ensure that the dispersing agent is uniformly mixed in the mixed solution;

(6) weighing diamond micropowder with required amount, and slowly and completely pouring the diamond micropowder into a mixing barrel from a feeding port at the top of the mixing barrel;

(7) mixing for 24h to ensure that the diamond micro powder is uniformly dispersed in the cutting fluid and ensure the subsequent cutting quality;

(8) and pouring the mixed mortar into a material barrel of a cutting machine for cutting.

The grain diameter of the diamond micro powder is 4-9 um, and the normal distribution of the grain diameter is as follows: 2.4% of 4um particles, 14.1% of 5um particles, 36.2% of 6um particles, 43.5% of 7um particles and 3.8% of 9um particles; the concentration of the diamond micro powder is 12 to 18 percent of the weight percentage of the mortar, and the organic dispersant is polyacrylamide; the mortar comprises, by weight, 60-70% of dihydric alcohol, 20-30% of polyglycol, 8-12% of polyacrylamide emulsion and 12-18% of drilling powder.

The diamond cutting fluid special for the silicon carbide crystal in the embodiment of the invention can comprise diamond micro powder, propylene glycol, polypropylene glycol and polyacrylamide emulsion. In this embodiment, 100 liters of diamond cutting fluid is prepared as an example; fig. 1 shows a particle size distribution diagram of the diamond fine powder of this embodiment. Fig. 2 shows a table of the particle size distribution of the diamond fine powder of this embodiment. It should be understood that the diamond particle size distribution used herein is not fixed, i.e., different cutting processes may employ diamond micropowder with different particle size distribution; FIG. 3 schematically shows a method for preparing a diamond cutting fluid for exclusive use in silicon carbide according to this embodiment,

A120L mixing barrel 1 is prepared, and the mixing barrel 1 is preferably made of transparent organic glass. Therefore, the mixing state of the mortar can be better observed;

a variable speed motor 2 is arranged on the top cover of the mixing barrel 1, the rotating speed of the stirring paddle 3 can be freely adjusted, and the uniformity of mortar mixing is better controlled;

slowly pouring 70L of propylene glycol into the mixing barrel 1 through the funnel 4 (as shown in figure 3a), turning on the stirring function, and adjusting the rotating speed to 20 rpm;

20L of polypropylene glycol was slowly poured into the mixing bowl 1 through the funnel 4 (see FIG. 3b), 10L of polyacrylamide emulsion was slowly poured into the mixing bowl 1 through the funnel 4 (see FIG. 3c), and 15Kg of fine diamond powder with a particle size distribution shown in FIG. 1 was slowly poured into the mixing bowl 1 through the funnel 4 (see FIG. 3 d), and mixed for 24h for use. Thus, the diamond micro powder can be completely and uniformly dispersed and suspended in the cutting fluid, and the uniformity and stability in the mortar cutting process are ensured;

and pouring the mixed diamond mortar into a mortar barrel of the cutting machine according to the use requirement through the liquid discharging port 5, and starting to cut the silicon carbide crystal in a multi-line manner.

Attention is paid to: and cleaning the old liquid in the mortar barrel of the cutting machine before filling the new mortar. Therefore, the cutting capability of the mortar can be better controlled, and the waste of materials is avoided.

In one example, the ingot to be cut is a 4-inch conductive 4H ingot with an overall length of 100mm, the cut thickness of the wafer is 510um, the diamond cutting fluid special for silicon carbide of the invention is adopted, and the corresponding linear gradient cutting rate is set for cutting.

The silicon carbide wafer after being cut has excellent geometric parameter results, and the cut silicon carbide wafer can be washed clean by clear water directly.

Table 1 shows some comparisons of the effect of conventional oily cutting mortars for silicon carbide crystals and cutting mortars according to the invention. Therefore, the silicon carbide crystal cutting method is simple and convenient to use, good in cutting surface shape, low in mortar viscosity and easy to clean.

Table 1: the effect of the conventional silicon carbide oily cutting mortar is compared with that of the invention

	TTV	Warp	BOW	Change in viscosity	Cleaning mode
						Conventional oily cutting mortar	<15	<30	<20	Big (a)	Multiple rinsing with kerosene and hot alkali liquor
The invention	<10	<20	<15	Small	Once cleaning with clear water or dilute alkali solution

The diamond cutting fluid special for silicon carbide can be prepared in different proportions according to different cutting processes, and is convenient to use. The diamond cutting fluid special for silicon carbide has the advantages of small viscosity change, good mortar particle dispersibility, good cutting surface shape and lower cost, is suitable for batch production of silicon carbide substrate slices or exploration of experimental silicon carbide wafer cutting processes, and has great industrial applicability. In addition, the diamond cutting fluid special for silicon carbide is easy to dissolve in water, the cut silicon carbide wafer can be easily cleaned by clear water or dilute alkali solution, the cleaning process is simple and convenient, and the diamond cutting fluid is very suitable for batch production of silicon carbide.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.