Method for forming an ohmic electrode

• US 6,110,813 A
• Filed: 04/03/1998
• Issued: 08/29/2000
• Est. Priority Date: 04/04/1997
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Kitabatake, Makoto, Masato, Hiroyuki, Kumabuchi, Yasuhito, Ota, Yorito
• Primary Examiner(s): Guay, John
• Assistant Examiner(s): Chambliss, Alonzo
• Application Number:
  US09/054,498
• Time in Patent Office: 879 Days
• Field of Search: 257/77, 257/198, 257/774, 438/597, 438/660, 438/662, 438/666, 438/931, 438/604, 438/605, 438/571, 438/586
• US Class Current: 438/597
• CPC Class Codes: H01L 21/0485 Ohmic electrodes
• CPC Class Codes: H01L 21/0495 Schottky electrodes
• CPC Class Codes: H01L 21/268 using electromagnetic radiation, e.g. laser radiation
• CPC Class Codes: H01L 21/8258 the substrate being a semiconductor, using a combination of technologies covered by H01L21/8206, H01L21/8213 , H01L21/822, H01L21/8252, H01L21/8254 or H01L21/8256
• CPC Class Codes: H01L 29/6606 the devices being controllable only by variation of the electric current supplied or the electric potential applied, to one or more of the electrodes carrying the current to be rectified, amplified, oscillated or switched, e.g. two-terminal devices
• CPC Class Codes: H01L 29/66068 the devices being controllable only by the electric current supplied or the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched, e.g. three-terminal devices
• CPC Class Codes: Y10S 438/931 Silicon carbide semiconductor

Abstract

A first metal film and a second metal film, both of which are made of Ni or the like, are deposited on the upper surface of a substrate made of SiC. In such a state, the interface between the first metal film and the substrate and the interface between the second metal film and the substrate both form a Schottky contact. Next, laser light is irradiated from above the upper surface of the substrate only onto the first metal film on the substrate after the diameter of the top end of the laser light has been reduced. Thus, since the metal-semiconductor interface between the first metal film and the substrate is turned into an alloy owing to the energy of the laser light without heating the entire substrate, an ohmic contact can be formed in the interface between the first metal film and the substrate. As a result, an ohmic electrode can be constituted by the first metal film.

Claims

1. A method for forming an ohmic electrode, comprising the steps of:

forming an insulator film on a surface of a substrate made of silicon carbide, the insulator film having an opening through which the surface of the substrate is exposed;

depositing a metal film in the opening on the substrate; and

forming an ohmic electrode of the metal film by heating the metal film through irradiation of laser light onto the substrate and thereby forming an ohmic contact between the metal film and the substrate.