Multi-functional micro electromechanical silicon carbide accelerometer

• US 6,769,303 B1
• Filed: 09/24/2003
• Issued: 08/03/2004
• Est. Priority Date: 04/12/2002
• Status: Active Grant

• Current Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Original Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Inventors: Okojie, Robert S.
• Primary Examiner(s): KWOK, HELEN C
• Application Number:
  US10/669,587
• Time in Patent Office: 314 Days
• Field of Search: 735/141.6, 735/142.9, 734/93, 257/414, 257/417, 257/E21.507, 257/E21.508
• US Class Current: 73/514.16
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81C 1/00182 Arrangements of deformable or non-deformable structures, e.g. membrane and cavity for use in a transducer
• CPC Class Codes: B81C 2201/0133 Wet etching
• CPC Class Codes: G01P 2015/084 the mass being suspended at more than one of its sides, e.g. membrane-type suspension, so as to permit multi-axis movement of the mass

Abstract

A method of bulk manufacturing SiC sensors is disclosed and claimed. Materials other than SiC may be used as the substrate material. Sensors requiring that the SiC substrate be pierced are also disclosed and claimed. A process flow reversal is employed whereby the metallization is applied first before the recesses are etched into or through the wafer. Aluminum is deposited on the entire planar surface of the metallization. Photoresist is spun onto the substantially planar surface of the Aluminum which is subsequently masked (and developed and removed). Unwanted Aluminum is etched with aqueous TMAH and subsequently the metallization is dry etched. Photoresist is spun onto the still substantially planar surface of Aluminum and oxide and then masked (and developed and removed) leaving the unimidized photoresist behind. Next, ITO is applied over the still substantially planar surface of Aluminum, oxide and unimidized photoresist. Unimidized and exposed photoresist and ITO directly above it are removed with Acetone. Next, deep reactive ion etching attacks exposed oxide not protected by ITO. Finally, hot phosphoric acid removes the Al and ITO enabling wires to connect with the metallization. The back side of the SiC wafer may be also be etched.

Claims

1. A SiC accelerometer comprising a proof mass and an ohmic contact, and said ohmic contact comprises layers of Titanium, Tantalum Disilicide, and Platinum.

2. A SiC accelerometer as claimed in claim 1 further comprising a substrate and a bridge, and wherein said bridge interconnects said proof mass and said substrate.

3. A SiC accelerometer as claimed in claim 2 wherein said bridge includes an n-type SiC epilayer.

4. An accelerometer comprising a proof mass and an ohmic contact, said ohmic contact comprises layers of Titanium, Tantalum Disilicide, and Platinum, a bridge and a substrate, said bridge interconnects said proof mass and said substrate, said bridge includes an epilayer, and, said substrate is selected from the group of SiC, AlN, BC, and Al₂O₃.

5. An accelerometer as claimed in claim 4 wherein said substrate is n-type.

6. An accelerometer as claimed in claim 4 wherein said substrate is p-type.