CN-116352899-B - Treatment method for cutting head and tail pieces of silicon carbide crystal

Abstract

The invention discloses a processing method suitable for cutting head and tail pieces of silicon carbide crystals. Therefore, the head and tail pieces of the cut silicon carbide crystal can be effectively utilized, and can be processed into standard substrate pieces after being processed by the method, no additional processing equipment is required, and the use cost is low. The processing method of the invention has simple operation, high control precision and high utilization rate of the cutting head and tail pieces, is suitable for being widely used for mass production or effective treatment of experimental silicon carbide cutting head and tail wafers, and has great industrial applicability.

Inventors

• CHEN HUI
• HE XIANHAN

Assignees

• 安徽微芯长江半导体材料有限公司

Dates

Publication Date

20260512

Application Date

20221130

Claims (1)

1. 1. The processing method of the head and tail pieces of the silicon carbide crystal cutting is characterized by comprising the following steps: S1, screening the cutting head and tail pieces, namely classifying the cutting head and tail pieces into four types according to the effective thickness and the thickness difference between the highest point and the lowest point of the uneven surface: thicker and flat wafers having an effective thickness greater than or equal to 450 μm and a thickness differential of less than or equal to 20 μm; thinner and flat wafers having an effective thickness of less than 450 μm and a thickness differential of less than or equal to 20 μm; thicker uneven wafers having an effective thickness greater than or equal to 450 μm and the thickness difference exceeding 20 μm; a thinner uneven wafer having an effective thickness of less than 450 μm and the thickness difference exceeding 20 μm; wherein the effective thickness is the thickness of the lowest point of the thickness of the wafer; s2, processing is carried out on different kinds of wafers respectively: the thicker flat wafers are subjected to secondary classification according to a section of 20 mu m, and then the wafers in the same thickness section are subjected to double-sided grinding; directly carrying out grinder thinning processing on the thinner flat wafer to a lower limit value of the standard thickness, and then carrying out subsequent standard processing; After the thicker uneven wafer is subjected to wax adhesion and ceramic disc adhesion, the uneven surface is ground flat by a single-sided grinder, and then double-sided grinding is adopted to reach the upper limit value of the standard thickness, wherein the diameter of the ceramic disc is more than 360mm, and the head and tail sheets with the maximum thickness and the minimum thickness which are close to each other are adhered to the same ceramic disc in the wax adhesion and disc adhesion process; And carrying out subsequent standard processing after carrying out thinning processing for a plurality of times until the standard thickness of the wafer is lower than the lower limit value, wherein the thinning amount of each time is set to be 10 mu m.

Description

Treatment method for cutting head and tail pieces of silicon carbide crystal Technical Field The invention relates to a processing method of head and tail slices after multi-line cutting of silicon carbide, in particular to a processing method of head and tail slices which are convenient to process according to a normal flow in wafers after multi-line cutting on a silicon carbide production line. Background Silicon carbide is used as a representative of a third-generation semiconductor, has the characteristics of large forbidden bandwidth, high breakdown electric field, high saturated electron drift velocity, large thermal conductivity and the like, can be applied to a high-voltage environment of more than 1200 volts, has obvious advantages in a severe environment, and meanwhile, the SiC crystal has high matched lattice constant and thermal expansion coefficient and good thermal conductivity with an epitaxial layer material GaN, so that the SiC crystal is an ideal substrate material of a GaN-based device, such as an LED and an LD. Therefore, siC crystal materials have become an indispensable substrate material in the field of semiconductor lighting technology. Silicon carbide and silicon carbide-based semiconductor materials have become a hotspot for research in countries around the world. The silicon carbide crystal is applied to a wafer which is required to be processed into a certain size by a device, 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 silicon carbide crystals have high hardness, the silicon carbide crystals have great difficulty in crystal processing, and the SiC crystal bars are cut into wafers with small warpage, uniform thickness and low cutting loss, which are important for subsequent grinding and polishing. Compared with the traditional cutting of the inner circle and the outer circle, the multi-wire cutting has the advantages of high cutting speed, high processing precision, high efficiency, long service life and the like, and has been widely applied to the high-efficiency cutting of silicon carbide wafers. Since chemical vapor deposition (PVT) methods are commonly used in the silicon carbide crystal industry today, single crystals of silicon carbide are grown. However, the growth characteristics of the PVT method determine that the thickness of the silicon carbide crystal grown by the method cannot be too thick, and the available thickness of a single grown silicon carbide ingot after end face shaping is generally 10-25 mm. Moreover, the hardness of the silicon carbide crystal is extremely high, the diamond cutting fluid is required to be used for multi-wire cutting, the cost of the diamond cutting fluid is relatively high, and meanwhile, the processing time of the wire cutting is relatively long. Therefore, in order to reduce the cost and improve the cutting efficiency, the industry generally adopts batch cutting after the polycrystalline ingots are bonded. Because the contact positions of the cutting lines at the head and tail parts of the ingot are different in the cutting process, the offset amount of the cutting lines in the head and tail part cutting process is different, so that the cutting head and tail parts with inconsistent thickness and surface type of tens of twenty pieces can be produced in each batch of cutting. Typically, such head-to-tail flakes can only be used as leave-on flakes to characterize the dislocation density of the crystal. However, some of the head and tail wafers meeting the requirement of certain thickness can be specially treated and can be used for producing wafer circulation, so that unnecessary waste can be avoided, and after all, the price of the single silicon carbide finished wafer is extremely high. Disclosure of Invention In view of the above problems of the conventional end-to-end slice processing after cutting silicon carbide, the inventors of the present application have realized that, for the end-to-end slice processing after cutting and processing of industrialized silicon carbide crystals, in order to ensure the best use of the cut end-to-end slice, avoid unnecessary material waste, and realize that the end-to-end wafer after cutting is subjected to special processing under the condition of meeting a certain thickness as much as possible, thereby being a processing method meeting the product requirements. In view of the above, the present invention provides a treatment method for silicon carbide cutting head and tail pieces, comprising the steps of, S1, screening the head and tail pieces of the cutting machine, wherein the head and tail pieces of the cutting machine are screened according to the effective piece thickness, the screening types comprise thicker flat wafers, thicker uneven wafers, thinner flat wafers and thinner uneven wafers, the effective thickness (the thickness of the lowest point of the thi