Method for manufacturing a micro-electro-mechanical structure

• US 20070072428A1
• Filed: 09/29/2005
• Published: 03/29/2007
• Est. Priority Date: 09/29/2005
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Delphi Technologies, Inc. (Aptiv PLC)
• Inventors: Chilcott, Dan
• Granted Patent: US 7,524,767 B2
• Time in Patent Office: Days
• US Class Current: 438/694
• CPC Class Codes: B81B 2203/033 Trenches
• CPC Class Codes: B81C 1/00531 Dry etching
• CPC Class Codes: B81C 2201/0132 Dry etching, i.e. plasma etching, barrel etching, reactive ion etching [RIE], sputter etching or ion milling
• CPC Class Codes: B81C 2201/0142 Processes for controlling etch progression not provided for in B81C2201/0136 - B81C2201/014

Abstract

A technique for manufacturing a micro-electro-mechanical (MEM) structure includes a number of steps. Initially, a substrate is provided. Next, a plurality of trenches are etched into the substrate with a first etch. Then, a charging layer is formed at a bottom of each of the trenches to form undercut trenches. Finally, a second etch is provided into the undercut trenches. The charging layer causes the second etch to laterally etch foots in the substrate between the undercut trenches. The footers undercut the substrate to release a portion of the substrate for providing a movable structure between the undercut trenches and above the footers.

Claims

1. A method for manufacturing a micro-electro-mechanical (MEM) structure, comprising the steps of:

providing a substrate;

etching a plurality of trenches into the substrate with a first etch;

forming a charging layer at a bottom of each of the trenches; and

providing a second etch into the trenches to form undercut trenches, wherein the charging layer causes the second etch to laterally etch footers in the substrate between the undercut trenches, and wherein the footers undercut the substrate to release a portion of the substrate for providing a moveable structure between the undercut trenches and above the footers.

2. The method of claim 1, wherein the charging layer is an oxide layer.

3. The method of claim 2, wherein the oxide layer is formed at the bottom of each of the trenches through a directional oxide deposition.

4. The method of claim 3, wherein the directional oxide deposition is a quartz sputtering deposition.

5. The method of claim 2, wherein the oxide layer is formed at the bottom of each of the trenches through a selective oxidation process.

6. The method of claim 1, wherein the first and second etches are deep reactive ion etches (DRIE).

7. The method of claim 1 further comprising the steps of:

etching at least one isolation trench in the substrate; and

filling the at least one isolation trench with a dielectric, wherein the at least one isolation trench electrically isolates the moveable structure.

8. The method of claim 1, wherein the substrate is made of silicon.

9. A method for manufacturing a micro-electro-mechanical (MEM) structure, comprising the steps of:

providing a substrate;

forming a dielectric isolation trench;

etching a plurality of undercut trenches into the substrate with a first etch, wherein the undercut trenches comprise a first height trench and a second height trench; and

providing a moveable structure between the undercut trenches.

10. The method of claim 9, wherein the first height trench is shallower than the isolation trench.

11. The method of claim 9, wherein the step of etching comprises forming the first height trench having a first size opening and forming the second height trench having a second size opening.

12. The method of claim 9 further comprising the steps of:

forming a charging layer at a bottom of each of a plurality of trenches; and

providing a second etch into the trenches, wherein the charging layer causes the second etch to laterally etch footers in the substrate between the trenches to form the undercut trenches, and wherein the footers undercut the substrate to release a portion of the substrate for providing a movable structure between the undercut trenches and above the footers.

13. The method of claim 12, wherein the charging layer is an oxide layer.

14. The method of claim 13, wherein the oxide layer is formed at the bottom of each of the trenches through a directional oxide deposition.

15. The method of claim 14, wherein the directional oxide deposition is a quartz sputtering deposition.

16. The method of claim 13, wherein the oxide layer is formed at the bottom of each of the trenches through a selective oxidation process.

17. The method of claim 9 further comprising the steps of:

etching at least one isolation trench in the substrate; and

filling the at least one isolation trench with a dielectric, wherein the at least one isolation trench electrically isolates the movable structure.

18. The method of claim 9, wherein the substrate is made of silicon.

19. A method for manufacturing a micro-electro-mechanical (MEM) structure, comprising the steps of:

providing a substrate;

etching a plurality of trenches into the substrate with a first etch;

forming a charging layer at a bottom of each of the trenches;

providing a second etch into the trenches to form undercut trenches, wherein the charging layer causes the second etch to laterally etch footers in the substrate between the undercut trenches, and wherein the footers undercut the substrate to release a portion of the substrate for providing a movable structure between the undercut trenches and above the footers;

etching at least one isolation trench in the substrate; and

filling the at least one isolation trench with a dielectric, wherein the at least one isolation trench electrically isolates the movable structure.

20. The method of claim 19, wherein the charging layer is an oxide layer.

21. The method of claim 20, wherein the oxide layer is formed at the bottom of each of the trenches through a directional oxide deposition.

22. The method of claim 21, wherein the directional oxide deposition is a quartz sputtering deposition.

23. The method of claim 20, wherein the oxide layer is formed at the bottom of each of the trenches through a selective oxidation process, and wherein the first and second etches are deep reactive ion etches (DRIE), where the substrate is made of silicon.

24. The method of claim 19 further comprising the step of:

etching an edge definition trench into the substrate to define edges of the movable structure.