Method for manufacturing semiconductor absolute pressure sensor units

• US 4,802,952 A
• Filed: 02/22/1988
• Issued: 02/07/1989
• Est. Priority Date: 03/06/1987
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Kobayashi, Ryoichi, Miyazaki, Atsushi, Suzuki, Seikou, Yamada, Kazuji, Kobori, Shigeyuki
• Primary Examiner(s): Powell, William A.
• Application Number:
  US07/158,750
• Time in Patent Office: 351 Days
• Field of Search: 156/629, 156/630, 156/633, 156/634, 156/645, 156/653, 156/655, 156/656, 156/657, 156/659.1, 156/662, 156/272.2, 29/610 SG, 29/620, 338/4, 338/42, 73/720, 73/721, 73/726, 73/727, 357/26, 437/226, 437/228
• US Class Current: 438/51
• 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: H01L 29/84 controllable by variation of applied mechanical force, e.g. of pressure
• CPC Class Codes: H10N 39/00 Integrated devices, or assemblies of multiple devices, comprising at least one piezoelectric, electrostrictive or magnetostrictive element covered by groups H10N30/00 – H10N35/00
• CPC Class Codes: Y10T 29/49103 Strain gauge making

Abstract

A method for manufacturing semiconductor absolute pressure sensor units includes anodically bonding a silicon sensor wafer (10) and a silicon cap wafer (12) with a borosilicate glass layer (32) disposed therebetween so as to surround respective sensor chips on the silicon sensor wafer (10) by introducing a matrix shaped conductive layer (28) in contact with and in alignment with the borosilicate glass layer (32), the matrix shaped conductive layer (28) is used as a negative electrode during anodic bonding operation so that a high bonding strength is obtained and sodium ions contained in the borosilicate glass layer (32) are kept away from bond regions after completing the anodically bonding operation.

Claims

1. A method for manufacturing semiconductor absolute pressure sensor units comprising:

a step of preparing a semiconductor sensor wafer (10) of one conductivity type having a plurality of first recesses (34) formed on one surface thereof in matrix so as to constitute diaphragms (36), thick boundary area supporting and surrounding the first recesses (34), a plurality of piezoresistive elements (14,

     16) of the other conductivity type formed on the other surface of the semiconductor sensor wafer (10) at the respective diaphragms (36), first conductive layer (24) forming a bridge circuit with the piezoresistive elements (14,16) at the respective diaphragms (36) and input and output terminals (26) therefor disposed on the thick boundary area of the respective diaphragms (36), glass layer (32) containing movable ions therein formed in matrix on the other surface of the semiconductor sensor wafer (10) over the thick boundary area, and second conductive strip layer (28) formed in contact with and in alignment with the glass layer (32);

a step of preparing a semiconductor cap wafer (12) of substantially the same thermal expansion coefficient as that of the semiconductor sensor wafer (10) having a plurality of second recesses (44) formed on one surface thereof in matrix, a plurality of first and second channels (46,

     47) formed on the one surface in matrix adjacent to the second recesses (44) arranged in matrix, and cutting marks (48, 50,

     52) formed on the other surface of the semiconductor cap wafer (12);

a step of aligning the semiconductor cap wafer (12) on the semiconductor sensor wafer (10) in such a manner that the second recesses (44) of the semiconductor cap wafer (12) overlie the respective diaphragms (36) of the semiconductor sensor wafer (10) from the other surface thereof so as to constitute reference pressure chambers (38) for the respective absolute pressure sensor units, the columns of the first channels (46) of the semiconductor cap wafer (12) overlie the input and output terminals (26) of the respective first conductive layers (24) and the columns of the second conductive strip layer (28) and the rows of the second channels (47) overlie the rows of the second conductive strip layer (28);

a step of applying a DC voltage between the semiconductor cap wafer (12) and the second conductive strip layer (28) on the semiconductor sensor wafer (10) in such a manner that the semiconductor cap wafer (12) is applied a positive potential and the second conductive strip layer (28) is applied a negative potential so as to bond the semiconductor cap wafer (12) to the semiconductor sensor wafer (10) with the glass layer (32) containing movable ions through anodic bonding process; and

a step of cutting the bonded semiconductor cap wafer (12) and semiconductor sensor wafer (10) along the cutting marks (48, 50,

     52) on the other surface of the semiconductor cap wafer (12) so as to produce a plurality of semiconductor absolute pressure sensor units.

2. A method for manufacturing semiconductor absolute pressure sensor units according to claim 1, wherein first conductive layer (24) and the second conductive strip layer (28) are formed simultaneously.

3. A method for manufacturing semiconductor absolute pressure sensor units according to claim 1, wherein the second conductive strip layer (28) is substantially cut away during said cutting step.

4. A method for manufacturing semiconductor absolute pressure sensor units according to claim 1, wherein the second conductive strip layer (28) is provided with terminals (30) for the DC voltage application at the periphery of the semiconductor sensor wafer (10).