Controlling stress in MEMS structures

• US 7,670,861 B2
• Filed: 01/26/2007
• Issued: 03/02/2010
• Est. Priority Date: 02/03/2006
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Fukuda, Hiroshi, Fujimori, Tsukasa, Hanaoka, Yuko
• Primary Examiner(s): Lee; Hsien-ming
• Assistant Examiner(s): Parendo; Kevin
• Application Number:
  US11/698,023
• Publication Number:
  US 20070249082A1
• Time in Patent Office: 1,131 Days
• Field of Search: 438 52- 53, 257/E21.573
• US Class Current: 438/53
• CPC Class Codes: B81C 1/00246 Monolithic integration, i.e. micromechanical structure and electronic processing unit are integrated on the same substrate
• CPC Class Codes: B81C 2203/0735 Post-CMOS, i.e. forming the micromechanical structure after the CMOS circuit
• CPC Class Codes: G01L 9/0042 Constructional details associated with semiconductive diaphragm sensors, e.g. etching, or constructional details of non-semiconductive diaphragms details about the integration or bonding of piezoresistor in or on the diaphragm G01L9/0052 and G01L9/0057 respectively
• CPC Class Codes: G01L 9/0073 using a semiconductive diaphragm
• CPC Class Codes: H01L 21/32053 of metal-silicide layers

Abstract

The objects of the present invention are to form MEMS structures of which stress is controlled while maintaining the performance of high-performance LSI, to integrate MEMS Structures and LSI on a single chip, to electrically and chemically protect the MEMS structure and to reduce the stress of the whole movable part of the MEMS structure. To achieve the above objects, a silicide film formable at a low temperature is used for the MEMS structure. The temperature at the silicide film deposition T1 is selected optionally with reference the heat treatment temperature T2 and the pseudo-crystallization temperature T3. T2, the temperature of manufacturing process after the silicide film deposition, is determined does not cause the degradation of the characteristics of the high-performance LSI indispensable. Thus, the residual stress of the MEMS structures may be controlled.

Claims

1. A manufacturing method of microelectromechanical system (MEMS) structures with semiconductor devices, comprising the steps of:

fabricating an electronic circuit on a substrate;

fabricating back-end of line layers on said electronic circuit;

fabricating a lower electrode connected with said back-end of line layers;

fabricating a sacrificial layer out of silicon oxide on said lower electrode;

fabricating movable electrode parts of MEMS structures out of a first silicide or a metal within a plurality of etching holes on said sacrificial layer;

wherein peripheral areas of said movable electrode parts are fixed,

removing said sacrificial layer by injecting hydrofluoric acid into said etching holes;

fabricating a silicon oxide film on said movable electrode parts to close said etching holes;

fabricating a silicon nitride film on said silicon oxide film;

fabricating a shield film made of a second silicide on said silicon nitride film;

wherein peripheral areas of said shield film are fixed, and

fabricating a photosensitive polyimide film on said silicon nitride film;

wherein

said MEMS structures, including said movable electrode parts and said shield film being formed by implementing a sputtering method at a film-fabricating heat treatment temperature T1, subsequently heating from T1 to a subsequent heat treatment temperature T2, which is higher than T1 and lower than a pseudo-crystallization temperature range T3,

wherein said pseudo-crystallization temperature range T3 is 400°

C.-450°

C.

2. The manufacturing method of MEMS structures according to claim 1, wherein said movable electrode film parts is fabricated with W or WSi.

3. The manufacturing method of MEMS structures according to claim 1, wherein said shield film is fabricated with WSi.