Method for processing IGBT wafer by utilizing gentle slope-shaped back surface

Abstract

The invention discloses a method for processing an IGBT wafer by utilizing a gentle slope-shaped back surface. The method comprises the following steps of: S1, completing a process before a wafer front surface metal process; S2, etching the back surface of the wafer to form a gentle slope; S3, completing the wafer back surface manufacturing process; S4, coating polyimide on the back surface; S5, manufacturing a front metal process; S6, coating polyimide on the front surface, and exposing a cutting channel after developing, curing and etching; S7, completing cutting through etching and using laser, and removing the polyimide on the front surface; and S8, attaching the wafer to a cutting die frame, and removing the polyimide on the back surface to separate crystal grains. According to the method, the gentle slope treatment is carried out on the back surface of the wafer, so that stress support can be provided at the edge, the limitation of back surface tempering temperature is overcome, and meanwhile, the polyimide is coated on the back surface of the wafer, so that the stress of the metal thick film can be buffered, and the thin wafer is prevented from being warped and damaged after the thick metal film is coated.

Description

technical field [0001] The invention relates to the field of semiconductor processing, in particular to a method for processing an IGBT wafer by using a gentle slope back surface. Background technique [0002] IGBT is a composite fully-controlled voltage-driven power semiconductor device composed of BJT (bipolar transistor) and MOS (insulated gate field effect transistor), and has high input impedance of MOSFET (metal-oxide semiconductor field effect transistor) And the advantages of low conduction voltage drop of GTR (power transistor). The saturation voltage of GTR is low, the carrying current density is large, but the driving current is large; the driving power of MOSFET is small, the switching speed is fast, but the conduction voltage drop is large, and the current carrying density is small. The IGBT combines the advantages of the above two devices, with low driving power and low saturation voltage. It is very suitable for the conversion system with a DC voltage of 600...

AI Technical Summary

Problems solved by technology

[0003]The current IGBT wafer production process is to complete the front side process of the wafer first, then bond the front side to the glass carrier, and then thin the back side and complete the subsequent The backside process of the wafer, but due to the high temperature steps in the backside process, the adhesive is a polymer material that can only withstand the heating process at a maximum of 350°C, and the metal process has been completed on the front side, and both AI and Cu can withstand heating at a maximum of 560°C Therefore, it cannot be implemented on a wafer bonded to a glass carrier, but the debonded wafer is prone to breakage and damage

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