Method for manufacturing silicon carbide semiconductor device

Abstract

After the front component structure is formed, from n ‑ P-type impurities are ion-implanted into the back surface (11b) of the silicon carbide substrate (11). Next, from n ‑ The back surface (11b) of the silicon carbide substrate (11) is irradiated with laser light to activate the p-type impurities to form a p-type collector layer (4). Next, in n ‑ A barrier metal layer is formed on the back surface (11b) of the silicon carbide substrate (11), and the barrier metal layer is sintered. Next, from n ‑ Proton implantation (16) with a range (17) at a position deeper than the p-type collector layer (4) is performed on the back surface (11b) side of the type silicon carbide substrate (11). Next, n is subjected to furnace annealing ‑ The entire silicon carbide substrate (11) is heated to convert protons into donors to form n-type silicon carbide substrates (11). + type field cutoff layer (3). At this time, n is reduced by reducing the disorder remaining in the proton passage region (14). ‑ Crystal state recovery of type silicon carbide substrate (11). This makes it possible to stably avoid electrical characteristic defects.

Description

technical field [0001] The invention relates to a method for manufacturing a silicon carbide semiconductor device. Background technique [0002] Examples of power semiconductor devices include semiconductor devices such as diodes made of silicon (Si) and IGBTs (Insulated Gate Bipolar Transistor: Insulated Gate Bipolar Transistor) having a withstand voltage of 400V, 600V, 1200V, 1700, 3300V or higher. These semiconductor devices are used in power conversion devices such as converters and inverters. Such power semiconductor devices are required to have good electrical characteristics such as low loss, high efficiency, and high breakdown resistance, and low cost. [0003] The following method has been proposed as a method of manufacturing the semiconductor device for electric power. First, after becoming n - type drift layer n - On the front side of the type semiconductor substrate, a front element structure such as a diffusion region and / or a MOS gate (insulated gate compos...

AI Technical Summary

Problems solved by technology

[0020] However, in the technologies described in the above-mentioned Patent Documents 1 to 8, there arises a problem that, in the above-mentioned Patent Document 1, the remaining of defects introduced into the semiconductor substrate by proton injection (carrier (electron / hole) mobility ) is described, but there is a problem of poor characteristics such as an increase in leakage current due to the existence of a crystal defect layer near the back surface of the substrate.

Images