System and method for direct bonding of substrates

• US 7,741,157 B2
• Filed: 07/21/2008
• Issued: 06/22/2010
• Est. Priority Date: 07/29/2005
• Status: Expired due to Fees

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Shih, Jennifer, Piehl, Arthur, Chen, Chien-Hua, Haluzak, Charles C
• Primary Examiner(s): Richards; N Drew
• Assistant Examiner(s): Chhaya; Swapneel
• Application Number:
  US12/177,033
• Publication Number:
  US 20080280398A1
• Time in Patent Office: 701 Days
• Field of Search: 257/682, 257/777, 257/85, 257/621, 257/774
• US Class Current: 438/115
• CPC Class Codes: B81B 2201/042 Micromirrors, not used as optical switches
• CPC Class Codes: B81C 1/00285 using materials for controlling the level of pressure, contaminants or moisture inside of the package, e.g. getters
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B

Abstract

A method of forming a MEMS (Micro-Electro-Mechanical System), includes forming an ambient port through a MEMS cap which defines a cavity containing a plurality of MEMS actuators therein; and bonding a lid arrangement to the MEMS cap to hermetically seal the ambient port.

Claims

1. A method of forming a MEMS (Micro-Electro-Mechanical System), comprising:

encasing a plurality of MEMS actuators in a sacrificial material;

forming an ambient port through a MEMS cap which defines a cavity, the cavity containing the plurality of MEMS actuators therein;

removing the sacrificial material using a fluid introduced into the cavity through the ambient port; and

bonding a lid arrangement to the MEMS cap to hermetically seal the ambient port.

2. The method of claim 1, further comprising:

forming the MEMS in an active light processing region; and

forming the ambient port in an inactive light processing region.

3. The method of claim 2, further comprising:

forming a recess in the lid arrangement so as to be in fluid communication with the ambient port, and in the inactive light processing region; and

disposing a contaminant absorbing material in the recess.

4. The method of claim 2, further comprising:

forming a light absorbing layer over the inactive light processing region.

5. The method of claim 3, further comprising:

forming a light absorbing layer in the recess and above the contaminant absorbing material.

6. The method of claim 1, wherein the process of removing the sacrificial material is carried out prior to the lid being bonded in place and the ambient portion being closed and subsequent to operations which produce conditions which are apt to damage MEMS actuators which are not covered with sacrificial material.

7. The method of claim 1, further comprising:

introducing a predetermined atmosphere into the cavity through the ambient port prior to bonding the lid to the MEMS cap.

8. The method of claim 7, further comprising controlling the pressure of the atmosphere in the cavity.

9. The method of claim 1, wherein the bonding process includes:

depositing a layer of bonding substrate material onto a lid of the lid arrangement;

plasma treating at least one of the layer of bonding substrate material on the lid and a bonding surface of the MEMS cap; and

bonding the bonding surface of the lid having the layer of bonding substrate material to the bonding surface of the MEMS cap.

10. The method according to claim 9, further comprising:

polishing the layer of bonding substrate material and the bonding surface of the MEMS cap prior to the process of plasma surface treatment.

11. The method according to claim 10, wherein the process of polishing includes using chemical-mechanical polishing.

12. The method according to claim 10, wherein said process of polishing includes polishing said layer and said MEMS cap to angstrom-level flatness.

13. The method according to claim 10, wherein said process of depositing includes depositing tetraethylorthosilicate, amorphous silicon, silicon nitride or glass frit.

14. The method according to claim 1, wherein the MEMS actuators include pixel plates forming part of a digital light display.

15. The method according to claim 3, wherein the contaminant absorbing material is a getter or a desiccant.

16. The method according to claim 3, wherein the contaminant absorbing material includes silicon dioxide.

17. A method of forming a MEMS (Micro-Electro-Mechanical System), comprising:

forming an ambient port through a MEMS cap which defines a cavity, the cavity containing a plurality of MEMS actuators therein;

introducing an anti-stiction material into the cavity prior to bonding of a lid arrangement to the MEMS cap;

bonding the lid arrangement to the MEMS cap to hermetically seal the ambient port; and

removing the anti-stiction material from an outboard surface of the MEMS cap during a plasma bonding process executed in connection with the bonding of the lid arrangement to the MEMS cap.

18. The method of claim 17, wherein the removal of anti-stiction material from an outboard surface of the MEMS cap during a plasma bonding process is achieved by introducing selected gases into a plasma chamber in a predetermined sequence or combination.

19. The method of claim 18, wherein oxygen is introduced into the plasma chamber for a predetermined short period to induce oxidation of the anti-stiction material on the outboard surface of the MEMS.

20. The method of claim 18, further comprising introducing a non-oxidizing gas to activate the surface to which the cap is to be bonded.