The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 26, 1999
Filed:
Feb. 02, 1994
Masaaki Ikegami, Hyogo, JP;
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
A semiconductor device in which stable and low resistance ohmic contact can be obtained in a base contact region without decreasing the emitter-base reverse breakdown voltage and the current amplification factor is disclosed. In this semiconductor device, p.sup.++ -type base contact layer 8 having an impurity concentration higher than that of p.sup.+ -type base layer 5 is formed in a region spaced apart by a predetermined distance from n.sup.+ -type emitter layer 7 on the main surface of p.sup.+ -type base layer 5. Thus, p.sup.++ -type base contact layer 8 having a high concentration does not contact n.sup.+ -type emitter layer 7, and also the current amplification factor and the emitter-base breakdown voltage are not decreased. Since p.sup.++ -type base contact layer 8 is formed so as to have a diffusion depth shallower than that of n.sup.+ -type emitter layer 7, the lateral spread of p.sup.++ -type base contact layer 8 can be reduced. Therefore, the side of p.sup.++ -type base contact layer 8 having a high concentration can be effectively prevented from contacting the side of n.sup.+ -type emitter layer 7 even when the elements are made smaller.