A Transistor and Method of Making

Patent metadata

Field	Value
Publication number	US-2016190293-A1
Application number	US-201213704613-A
Country	US
Kind code	A1
Filing date	Dec 14, 2012
Priority date	Dec 14, 2012
Publication date	Jun 30, 2016
Grant date	—

Abstract

A SiGe HBT has an inverted heterojunction structure, where the emitter layer is formed prior to the base layer and the collector layer. The frequency performance of the SiGe HBT is significantly improved through a better thermal process budget for the base profile, essential for higher cut-off frequency (f T ) and a minimal collector-base area for a reduced parasitic capacitance, essential for higher maximum oscillation frequency (f max ). This inverted heterojunction structure can be fabricated by using ALE processes to form an emitter on a preformed epitaxial silicide, a base over the emitter and a collector over the base.

First claim

1 . An HBT, comprising:
an ultrathin single crystalline epitaxial metal silicide layer grown on a semiconductor substrate; a single crystalline silicon emitter formed over the metal silicide layer; a base formed over the emitter; and a single crystalline silicon collector formed over the base; wherein the HBT has an inverted architecture with the collector being close to a surface of the HBT.

2 . The HBT of claim 1 , wherein the single crystal epitaxial metal silicide is an ultrathin epitaxial NiSi 2 films on a Si(100) substrate.

3 . The HBT of claim 1 , wherein a thickness of the ultrathin single crystalline epitaxial metal silicide layer is 10 nm or less, while a width of the base is 10 nm or less.

4 . The HBT of claim 1 , wherein the emitter is carbon doped.

5 . The HBT of claim 1 , wherein the emitter and the collector each has a thickness that is about 10 nm or less.

6 . The HBT of claim 1 , wherein at least one of the emitter, the base, and the collector is formed by at least one ALE process.

7 . The HBT of claim 1 , wherein the base comprises SiGe.

8 . The HBT of claim 1 , further comprising metal silicide contacts on the emitter, the base and the collector, respectively, the metal silicide contacts having very low resistivity of about 45 μΩ-cm.

9 . The HGT of claim 1 , wherein the collector is stressed in the transport direction to enhance electron mobility.

10 . The HBT of claim 1 , wherein the collector is lightly-doped and silicide-shunted.

11 . The HBT of claim 1 , wherein the base is strain engineered to enhance lateral hole and vertical electron conduction in the base.

12 . The HBT of claim 11 , wherein the base is further stressed in an additional direction.

13 . A method of making an HBT for operating in the TeraHertz Gap, comprising:
epitaxially growing a single crystal metal silicide layer on a semiconductor substrate; epitaxially growing a single crystal silicon emitter on the metal silicide layer; epitaxially growing an base over the emitter; and epitaxially growing a single crystal silicon collector on the base.

14 . The method of claim 13 , wherein the metal silicide layer is NiSi 2 grown on Si(100) using an SSR process.

15 . The method of claim 13 , wherein the SSR process comprises sputter-deposition of a Ni film that is equal to or less than about ˜2-nm thick followed by heat treatment.

16 . The method of claim 13 , wherein the emitter is grown using an ALE process.

17 . The method of claim 16 , wherein the emitter is in situ doped with carbon during the ALE process.

18 . The method of claim 16 , wherein photons from a laser source are used during the ALE process to help release hydrogen atoms from a substrate surface.

19 . The method of claim 16 , further comprising stressing the Si emitter layer;

20 . The method of claim 16 , further comprising stressing the SiGe base layer in multiple directions.

21 . (canceled)

Assignees

• Wu Dongping
• Fu Chaochao
• Zhang Wei
• Zhang Shili
• Univ Fudan

Inventors

• Wu Dongping
• Fu Chaochao
• Zhang Wei
• Zhang Shili

Classifications

• H10P14/3411

  Silicon, silicon germanium or germanium · CPC title

• H10P14/24

  using chemical vapour deposition [CVD] · CPC title

• H10P14/3458

  Monocrystalline · CPC title

• H10P14/3438

  Doping during depositing · CPC title

• H10P14/44

  Physical vapour deposition [PVD] · CPC title