Accelerometer with compatibility to complementary metal-oxide-semiconductor technologies

Patent metadata

Field	Value
Publication number	US-10539587-B2
Application number	US-201715422138-A
Country	US
Kind code	B2
Filing date	Feb 1, 2017
Priority date	Feb 1, 2017
Publication date	Jan 21, 2020
Grant date	Jan 21, 2020

Abstract

An accelerometer may include a seismic mass to flex based on acceleration components perpendicular to a surface of a substrate. The seismic mass may include a first electrode and a portion of the substrate. A first surface of the seismic mass may be adjacent to a first cavity in the substrate, and a second surface of the seismic mass being adjacent to a second cavity. The first surface of the seismic mass and the second surface of the seismic mass may be on opposite sides of the seismic mass. The accelerometer may include a second electrode separated from the second surface of the seismic mass by at least the second cavity.

First claim

What is claimed is:

1. An accelerometer, comprising:
a seismic mass to flex based on acceleration components perpendicular to a surface of a substrate,
the seismic mass including a first electrode, an oxide layer, and a portion of the substrate,
a first surface of the seismic mass being adjacent to a first cavity in the substrate, and
a second surface of the seismic mass being adjacent to a second cavity,
the first surface of the seismic mass and the second surface of the seismic mass being on opposite sides of the seismic mass; and

a second electrode separated from the second surface of the seismic mass by at least the second cavity.

2. The accelerometer of claim 1 , wherein the portion of the substrate included in the seismic mass includes migrated substrate particles.

3. The accelerometer of claim 1 , wherein the first cavity is formed using a silicon-on-nothing process.

4. The accelerometer of claim 1 , wherein the second cavity is formed by removing a sacrificial layer deposited on at least the seismic mass.

5. The accelerometer of claim 1 , further comprising a set of oxide layers that define the second cavity.

6. The accelerometer of claim 1 , wherein the first electrode includes a portion of an electrode layer that is formed on the second surface of the seismic mass,
the electrode layer being separated from the surface of the substrate by the oxide layer.

7. The accelerometer of claim 1 , wherein the first electrode is formed by diffusing a counter-doping species into the portion of the substrate included in the seismic mass.

8. A semiconductor device, comprising:
a substrate including a first cavity;
a seismic mass formed of a portion of the substrate and a first electrode,
a first surface of the seismic mass being adjacent to the first cavity, and
a second surface of the seismic mass being adjacent to a second cavity,
the first electrode being located at the second surface of the seismic mass, and
the first surface of the seismic mass and the second surface of the seismic mass being on opposite sides of the seismic mass;

an oxide layer that defines the second cavity; and
a second electrode separated from the second surface of the seismic mass by a portion of the oxide layer and the second cavity.

9. The semiconductor device of claim 8 , wherein the first cavity is formed using a silicon-on-nothing (SON) process.

10. The semiconductor device of claim 9 , wherein the portion of the substrate included in the seismic mass includes particles having migrated as a result of the SON process.

11. The semiconductor device of claim 8 , wherein the second cavity is formed by removing a sacrificial layer from between the second surface of the seismic mass and the oxide layer.

12. The semiconductor device of claim 11 , wherein the sacrificial layer is a carbon sacrificial layer.

13. The semiconductor device of claim 8 , wherein the first electrode comprises an electrode layer formed on an other oxide layer,
the other oxide layer being formed on the second surface of the seismic mass.

14. The semiconductor device of claim 13 , wherein the electrode layer is formed from a polycrystalline material.

15. The semiconductor device of claim 8 , wherein the first electrode is formed by diffusing a counter-doping species into the portion of the substrate included in the seismic mass.

16. The semiconductor device of claim 8 , wherein the second electrode comprises a metallic layer.

17. The semiconductor device of claim 8 , wherein another portion of the oxide layer is formed on a portion of the second electrode.

18. The semiconductor device of claim 8 , wherein manufacturing of the semiconductor device is integrated with a complementary metal-oxide-semiconductor (CMOS) processing sequence.

19. A method for manufacturing a semiconductor device, the method comprising:
obtaining a substrate including a first cavity below a surface of the substrate;
forming a first oxide layer on the surface of the substrate;
forming a first electrode layer on the first oxide layer to form a first electrode;
etching one or more trenches in the first electrode layer, the first oxide layer, and a portion of the substrate to form a seismic mass that includes the first electrode, a portion of the first oxide layer, and the portion of the substrate,
the portion of the substrate being located between the first cavity and the surface of the substrate;

forming a sacrificial layer on at least the seismic mass;
forming a second oxide layer on the sacrificial layer;
forming a second electrode layer on the second oxide layer to form a second electrode; and
removing the sacrificial layer to form a second cavity,
the second electrode being separated from the seismic mass by a portion of the second oxide layer and the second cavity.

20. The method of claim 19 , wherein the portion of the substrate included in the seismic mass includes substrate particles having migrated as a result of a silicon-on-nothing (SON) process.

Assignees

• Infineon Technologies Dresden Gmbh

Inventors

• Kautzsch Thoralf
• Bieselt Steffen

Classifications

• G01P15/125

  by capacitive pick-up · CPC title

• G01P15/0802 Primary

  Details · CPC title