Structures for reducing and preventing stress and tensions during processing of silicon with the aid of melting by a laser

Patent metadata

Field	Value
Publication number	US-10017375-B2
Application number	US-201615291142-A
Country	US
Kind code	B2
Filing date	Oct 12, 2016
Priority date	Oct 26, 2015
Publication date	Jul 10, 2018
Grant date	Jul 10, 2018

Abstract

A method is provided for manufacturing a micromechanical component including a substrate and a cap connected to the substrate and together with the substrate enclosing a first cavity, a first pressure prevailing and a first gas mixture with a first chemical composition being enclosed in the first cavity. An access opening, connecting the first cavity to surroundings of the micromechanical component, is formed in the substrate or in the cap. The first pressure and/or the first chemical composition are adjusted in the first cavity. The access opening is sealed by introducing energy and heat into an absorbing part of the substrate or the cap with the aid of a laser. A recess is formed in a surface of the substrate or of the cap facing away from the first cavity in the area of the access opening for reducing local stresses occurring at a sealed access opening.

First claim

What is claimed is:

1. A method for manufacturing a micromechanical component including a substrate and a cap connected to the substrate and together with the substrate enclosing a first cavity, a first pressure prevailing and a first gas mixture with a first chemical composition being enclosed in the first cavity, the method comprising:
in a first step, forming an access opening connecting the first cavity to surroundings of the micromechanical component in the substrate or in the cap;
in a second step, adjusting at least one of the first pressure and the first chemical composition in the first cavity;
in a third step, sealing the access opening by introducing energy and heat into an absorbing part of the substrate or the cap with the aid of a laser; and
in a fourth step, forming a recess in a surface of the substrate or of the cap facing away from the first cavity by isotropically etched into the surface after anisotropic etching in an area of the access opening for reducing local stresses occurring at the sealed access opening, wherein a distance from the area to the absorbing part is equal to at most a radius of the absorbing part, wherein the recess is not situated within the absorbing part.

2. The method as recited in claim 1 , wherein the cap together with the substrate encloses a second cavity, a second pressure prevailing and a second gas mixture with a second chemical composition being enclosed in the second cavity.

3. The method as recited in claim 1 , wherein in the fourth step, an additional recess or a plurality of additional recesses are formed in the surface in the area of the access opening to reduce local stresses occurring at the sealed access opening.

4. The method as recited in claim 1 , wherein at least one of the recess, an additional recess, and a plurality of additional recesses is formed in a plane extending in parallel to the surface which is rotationally symmetrical to the access opening or to the absorbing part of the substrate or of the cap.

5. The method as recited in claim 4 , wherein the at least one of the recess, the additional recess, and the plurality of additional recesses are formed in such a way that a first extension of the at least one of the recess, the additional recess, and the plurality of additional recesses perpendicular to the surface corresponds to a second extension of the absorbing part of the substrate or of the cap.

6. The method as recited in claim 4 , wherein the at least one of the recess, the additional recess, and the plurality of additional recesses, are formed chronologically after the third step, so that the at least one of the recess, the additional recess, and the plurality of additional recesses includes a ring-shaped cavity or a plurality of ring-shaped cavities.

7. A method for manufacturing a micromechanical component including a substrate and a cap connected to the substrate and together with the substrate enclosing a first cavity, a first pressure prevailing and a first gas mixture with a first chemical composition being enclosed in the first cavity, the method comprising:
in a first step, forming an access opening connecting the first cavity to surroundings of the micromechanical component in the substrate or in the cap;
in a second step, adjusting at least one of the first pressure and the first chemical composition in the first cavity;
in a third step, sealing the access opening by introducing energy and heat into an absorbing part of the substrate or the cap with the aid of a laser; and
in a fourth step, forming a recess in a surface of the substrate or of the cap facing away from the first cavity in an area of the access opening for reducing local stresses occurring at the sealed access opening,
wherein at least one of the recess, an additional recess, and a plurality of additional recesses is formed in a plane extending in parallel to the surface which is rotationally symmetrical to the access opening or to the absorbing part of the substrate or of the cap,
wherein the at least one of the recess, the additional recess, and the plurality of additional recesses is formed rotationally symmetrical to a center of mass of the absorbing part of the substrate or of the cap.

Assignees

• Bosch Gmbh Robert

Inventors

• Reichenbach Frank
• Schade Till
• Reinmuth Jochen
• Kappe Philip
• Ilin Alexander
• Ametowobla Mawuli
• Amthor Julia

Classifications

• B81C2201/0132

  Dry etching, i.e. plasma etching, barrel etching, reactive ion etching [RIE], sputter etching or ion milling · CPC title

• B81C2203/0109

  Bonding an individual cap on the substrate · CPC title

• B81C1/00277

  for maintaining a controlled atmosphere inside of the cavity containing the MEMS · CPC title

• B81C2201/0143

  Focussed beam, i.e. laser, ion or e-beam · CPC title

• B81C1/00666

  Treatments for controlling internal stress or strain in MEMS structures · CPC title