Epitaxially grown silicon layers with relatively long minority carrier lifetimes

• US 4,247,859 A
• Filed: 11/29/1974
• Issued: 01/27/1981
• Est. Priority Date: 11/29/1974
• Status: Expired due to Term

• Current Assignee: Northrop Grumman Corporation
• Original Assignee: Westinghouse Electric Company LLC (Brookfield Asset Management Incorporated)
• Inventors: Schroder, Dieter K., Rai-Choudhury, Prosenjit
• Primary Examiner(s): Larkins, William D.
• Application Number:
  US05/528,956
• Time in Patent Office: 2,251 Days
• Field of Search: 357/4, 357/48, 357/49, 357/42, 357/89
• US Class Current: 257/352
• CPC Class Codes: H01L 27/092 complementary MIS field-effect transistors
• CPC Class Codes: H01L 27/12 the substrate being other than a semiconductor body, e.g. an insulating body
• CPC Class Codes: H01L 29/7317 Bipolar thin film transistors
• CPC Class Codes: H01L 29/7325 having an emitter-base junction leaving at a main surface and a base-collector junction leaving at a peripheral surface of the body, e.g. mesa planar transistor

Abstract

A semiconductor device such as a film or hybrid integrated circuit is provided having a relatively lightly doped, epitaxially grown silicon layer with a relatively long minority carrier lifetime. The lightly doped silicon layer of less than about 1×10¹⁷ per cm³ is grown on a heavily doped silicon layer of greater than about 1×10¹⁹ and preferably greater than about 1×10²⁰ per cm³ formed with phosphorus or boron impurity. The heavily doped silicon layer is preferably formed, either in a semiconductor body or an epitaxial layer on an insulator substrate, preferably by diffusing the impurity into the body or epitaxial layer. Preferably, the semiconductor device is a thin-film device and most desirably a silicon-on-sapphire device.

Claims

1. A silicon-on-sapphire semiconductor having a region with a relatively long minority carrier lifetime comprised of:

(a) a sapphire substrate with a major surface;

(b) a heavily doped epitaxial silicon layer with a surface impurity concentration greater than about 1×

10¹⁹ per cm³ of phosphorus impurity over the major surface of the sapphire substrate; and

(c) a relatively lightly doped epitaxial silicon layer with an impurity concentration less than about 1×

10¹⁷ per cm³ adjoining the heavily doped epitaxial silicon layer, said lightly doped epitaxial silicon layer having a relatively long minority carrier lifetime of greater than 50 nanoseconds.

2. A silicon-on-sapphire semiconductor device having a region with a relatively long minority carrier lifetime comprised of:

(a) a sapphire substrate with a major surface;

(b) a heavily doped epitaxial silicon layer with a surface impurity concentration greater than about 1×

10²⁰ per cm³ of phosphorus impurity over the major surface of the sapphire substrate; and

(c) a relatively lightly doped epitaxial silicon layer with an impurity concentration less than about 1×

10¹⁷ per cm³ adjoining the heavily doped epitaxial silicon layer, said lightly doped epitaxial silicon layer having a relatively long minority carrier lifetime of greater than 50 nanoseconds.

3. A silicon-on-sapphire semiconductor device having a region with a relatively long minority carrier lifetime comprised of:

(a) a sapphire substrate with a major surface;

(b) a heavily doped epitaxial silicon layer with a surface impurity concentration greater than about 1×

10¹⁹ per cm³ of boron impurity over the major surface of the sapphire substrate; and

(c) a relatively lightly doped epitaxial silicon layer with an impurity concentration less than about 1×

10¹⁷ per cm³ adjoining the heavily doped epitaxial silicon layer, said lightly doped epitaxial silicon layer having a relatively long minority carrier lifetime of greater than 50 nanoseconds.