Patent ID: 10325776

Abstract:
An n-type layer (3) is formed by implanting an n-type impurity in a back surface of a Si substrate (1). A recess (4) is formed in the back surface of the Si substrate (1). After forming the n-type layer (3), an oxide film (5) is formed on the back surface and in the recess (4). The oxide film (5) on the back surface is removed while the oxide film (5) in the recess (4) is left. After removing the oxide film (5), an Al—Si film (6) is formed on the back surface. A metal electrode (7) is formed on the Al—Si film (6). The oxide film (5) in the recess (4) prevents Al from diffusing from the Al—Si film (6) into the Si substrate (1) through the recess (4).