Integrated structures of acoustic wave device and varactor, and acoustic wave device, varactor and power amplifier, and fabrication methods thereof

Patent metadata

Field	Value
Publication number	US-9905610-B2
Application number	US-201715445490-A
Country	US
Kind code	B2
Filing date	Feb 28, 2017
Priority date	Dec 30, 2014
Publication date	Feb 27, 2018
Grant date	Feb 27, 2018

Abstract

An integrated structure of acoustic wave device and varactor comprises an acoustic wave device and a varactor formed on a first part and a second part of a semiconductor substrate respectively. The acoustic wave device comprises an acoustic wave device upper structure and a first part of a bottom epitaxial structure. The acoustic wave device upper structure is formed on the first part of the bottom epitaxial structure. The varactor comprises a varactor upper structure and a second part of the bottom epitaxial structure. The varactor upper structure is formed on the second part of the bottom epitaxial structure. The integrated structure of the acoustic wave device and the varactor formed on the same semiconductor substrate is capable of reducing the module size, optimizing the impedance matching, and reducing the signal loss between the varactor and the acoustic wave device.

First claim

What is claimed is:

1. An integrated structure of acoustic wave device and varactor comprising:
a semiconductor substrate, wherein said semiconductor substrate includes a first part and a second part of said semiconductor substrate;
an acoustic wave device formed on said first part of said semiconductor substrate, wherein said acoustic wave device comprises an acoustic wave device upper structure and a first part of a bottom epitaxial structure, wherein said bottom epitaxial structure is formed on said semiconductor substrate, wherein said bottom epitaxial structure includes said first part and a second part of said bottom epitaxial structure formed on said first part and said second part of said semiconductor substrate respectively, wherein said acoustic wave device upper structure is formed on said first part of said bottom epitaxial structure; and
a varactor formed on said second part of said semiconductor substrate, wherein said varactor comprises a varactor upper structure and said second part of said bottom epitaxial structure, wherein said varactor upper structure is formed on said second part of said bottom epitaxial structure;
wherein the integrated structure of said acoustic wave device and said varactor formed on the same said semiconductor substrate is capable of reducing the module size, optimizing the impedance matching, and reducing the signal loss between said varactor and said acoustic wave device.

2. The integrated structure of acoustic wave device and varactor according to claim 1 , wherein said first part of said bottom epitaxial structure comprises a bottom epitaxial structure recess on the top of said bottom epitaxial structure, wherein a bottom of said bottom epitaxial structure recess is said bottom epitaxial structure or said semiconductor substrate; and wherein said acoustic wave device upper structure comprises:
an acoustic wave device protection layer formed on said first part of said bottom epitaxial structure, wherein said acoustic wave device protection layer comprises an acoustic wave device protection layer recess on a bottom of said acoustic wave device protection layer and an upwardly protruding acoustic wave device protection layer mesa right above said acoustic wave device protection layer recess, and wherein said acoustic wave device protection layer recess is located right above said bottom epitaxial structure recess, said acoustic wave device protection layer recess is communicated with said bottom epitaxial structure recess, and wherein said acoustic wave device protection layer recess and said bottom epitaxial structure recess have a boundary therebetween and said boundary is extended from a top surface of said bottom epitaxial structure; and
an acoustic wave resonance structure formed on said acoustic wave device protection layer mesa, said acoustic wave resonance structure including:
an acoustic wave device bottom electrode formed on said acoustic wave device protection layer mesa;
a dielectric layer formed on said acoustic wave device bottom electrode; and
an acoustic wave device top electrode formed on said dielectric layer;

wherein a gap between said acoustic wave device protection layer and said bottom of said bottom epitaxial structure recess is increased by the communication of said acoustic wave device protection layer recess and said bottom epitaxial structure recess, so as to avoid the contact of said acoustic wave device protection layer and said bottom of said bottom epitaxial structure recess when said acoustic wave device is affected by stress such that said acoustic wave device protection layer is bended downwardly.

3. The integrated structure of acoustic wave device and varactor according to claim 2 , wherein said acoustic wave device protection layer recess has an opening smaller than or equal to that of said bottom epitaxial structure recess.

4. The integrated structure of acoustic wave device and varactor according to claim 1 , wherein said acoustic wave device comprises:
an auxiliary layer formed on said first part of said bottom epitaxial structure;
a dielectric layer formed on said auxiliary layer; and
an interdigital transducer electrode formed on said dielectric layer.

5. The integrated structure of acoustic wave device and varactor according to claim 1 , wherein said bottom epitaxial structure comprises a bottom n-type doped layer; wherein said varactor upper structure comprises a varactor middle epitaxial structure mesa, a varactor top electrode and a varactor bottom electrode, wherein said varactor top electrode is formed on said varactor middle epitaxial structure mesa, wherein said varactor bottom electrode is formed on said second part of said bottom epitaxial structure, wherein said varactor middle epitaxial structure mesa comprises:
a middle n-type graded doped layer formed on said bottom epitaxial structure; and
a middle p-type doped layer formed on said middle n-type graded doped layer.

6. The integrated structure of acoustic wave device and varactor according to claim 5 , wherein a thickness of said bottom n-type doped layer is between 200 nm and 600 nm, wherein a thickness of said middle n-type graded doped layer is between 100 nm and 2000 nm, and wherein a thickness of said middle p-type doped layer is between 10 nm and 150 nm.

7. The integrated structure of acoustic wave device and varactor according to claim 5 , wherein said bottom n-type doped layer is made of InGaAs; said middle n-type graded doped layer is made of InGaAs; and said middle p-type doped layer is made of InGaAs.

8. The integrated structure of acoustic wave device and varactor according to claim 7 , wherein said varactor middle epitaxial structure mesa further comprises a varactor ledge layer formed on said middle p-type doped layer, wherein said varactor ledge layer is n-type doped and made of InGaAs, and wherein a thickness of said varactor ledge layer is between 1 nm and 60 nm.

9. The integrated structure of acoustic wave device and varactor according to claim 7 , wherein said bottom epitaxial structure further comprises an etching stop layer formed on said bottom n-type doped layer, wherein said etching stop layer is made of InP; wherein said etching stop layer has a varactor bottom electrode recess, wherein a bottom of said varactor bottom electrode recess is said bottom n-type doped layer such that said varactor bottom electrode is formed on said bottom n-type doped layer within said varactor bottom electrode recess.

10. The integrated structure of acoustic wave device and varactor according to claim 5 , wherein said bottom n-type doped layer is made of GaAs; said middle n-type graded doped layer is made of GaAs; and said middle p-type doped layer is made of GaAs.

11. The integrated structure of acoustic wave device and varactor according to claim 10 , wherein said varactor middle epitaxial structure mesa further comprises a varactor ledge layer formed on said middle p-type doped layer, wherein said varactor ledge layer is n-type doped and made of InGaP, and wherein a thickness of said varactor ledge layer is between 1 nm and 60 nm.

12. The integrated structure of acoustic wave device and varactor according to claim 10 , wherein said bottom epitaxial structure further comprises an etching stop layer formed on said bottom n-type doped layer, wherein said etching stop layer is made of InGaP; wherein said etching stop layer has a varactor bottom electrode recess, wherein a bottom of said varactor bottom electrode recess is said bottom n-type doped layer such that said varactor bottom electrode is formed on said bottom n-type doped layer within said varactor bottom electrode recess.

13. The integrated struc

Assignees

• Win Semiconductors Corp

Inventors

• Tsai Shu Hsiao
• Lin Re Ching
• Liao Pei Chun
• Lin Cheng Kuo
• Chin Yung Chung
• Chiang Chih Feng

Classifications

• H10W44/234

  Arrangements for impedance matching · CPC title

• H10W44/20

  at high-frequency [HF] or radio frequency [RF] · CPC title

• H10D62/854

  further characterised by the dopants · CPC title

• H10D84/0112

  Integrating together multiple components covered by H10D8/00, H10D10/00 or H10D18/00, e.g. integrating multiple BJTs · CPC title

• H10D84/05

  using Group III-V technology · CPC title