Method of fabrication of silicon pressure transducer sensor units

Claim 1

THE METHOD OF FORMING SEMICONDUCTOR TRANSDUCER SENSORS COMPRISING THE STEPS OF: FORMING A SEMICONDUCTOR LAYER ON AN UPPER SURFACE OF A SEMICONDUCTOR SUBSTRATE, FORMING A PLURALITY OF SPACED APART CAVITY REGIONS IN SAID SUBSTRATE, SAID LAYER REMAININ TO SERE AS FLEXIBLE DIAPHRAGMS FOR PIEZORESISTOR BRIDGE CIRCUITS FORMED IN EACH OF SAID DIAPHRAGMS, FORMING A BACKING PLATE OF SEMICONDUCTOR MAERIAL INCLUDING FORMING AN OXIDE LAYER ON THE UPPER SURFACE OF SAID BACKING PLATE FORMING A PLURALITY OF SPACED APART OPENING IN THE UNDERSIDE OF THE BACKING PLATE SO AS TO BE IN ALIGMENT WITH THE CAVITY REGIONS IN SAID SUBSTRATE, SAID OPENING FORMING A PORTION OF A PORT AT EACH CAVITY REGION POSITION, SAID PORTS STOPPING AT THE OXIDE LAYER FORMED ON THE UPPER SURFACE OF SAID BACKING PLATE,

Claim 2

THE METHOD OF FORMING SEMICONDUCTOR TRANSDUCER SENSORS COMPRISING THE STEPS OF: FORMING A SEMICONDUCTOR LAYER ON AN UPPER SURFACE OF A SEMICONDUCTOR SUBSTRATE, FORMING A PLURALITY OF SPACED APART CAVITY REGIONS IN SAID SUBSTRATE, SAID LAYER REMAININ TO SERE AS FLEXIBLE DIAPHRAGMS FOR PIEZORESISTOR BRIDGE CIRCUITS FORMED IN EACH OF SAID DIAPHRAGMS, FORMING A BACKING PLATE OF SEMICONDUCTOR MAERIAL INCLUDING FORMING AN OXIDE LAYER ON THE UPPER SURFACE OF SAID BACKING PLATE FORMING A PLURALITY OF SPACED APART OPENING IN THE UNDERSIDE OF THE BACKING PLATE SO AS TO BE IN ALIGMENT WITH THE CAVITY REGIONS IN SAID SUBSTRATE, SAID OPENING FORMING A PORTION OF A PORT AT EACH CAVITY REGION POSITION, SAID PORTS STOPPING AT THE OXIDE LAYER FORMED ON THE UPPER SURFACE OF SAID BACKING PLATE,

Claim 4

The method of forming semiconductor transducer sensors comprising the steps of: forming a semiconductor layer on an upper surface of a semiconductor substrate, etching a plurality of spaced apart cavity regions into said substrate, said layer remaining to serve as flexible diaphragms for piezoresistor bridge circuits formed in each of said diaphragms, forming a backing plate of semiconductor material including forming an oxide layer on the upper and lower surfaces of said backing plate, forming a mask in the oxide layer of the underside of the backing plate, said mask having spaced apart openings therein so as to be in alignment with the cavity regions in said substrate, etching away the semiconductor material in said openings such that a portion of a port is formed at each cavity region position, said etched ports stopping at the oxide layer formed on the upper surface of said backing plate, sealing the upper surface of said backing plate to said substrate under vacuum such that evacuated cavities are formed in said substrate, said cavities including said diaphragms as one wall of each cavity and said oxide layer in said ports serving as a portion of another wall of each cavity whereby absolute pressure sensor cavities are formed in the substrate, electrically testing the bridge circuits in the flexible diaphragms of the cavities, and thereafter converting said absolute pressure sensor cavities to ambient pressure sensor cavities by puncturing said oxide layers in said ports in said backing plate, thereby establishing a port opening into the associated cavity.

Claim 5

The method of forming semiconductor transducer sensors comprising the steps of: forming a semiconductor layer on an upper surface of a semiconductor substrate, etching a plurality of spaced apart cavity regions into said substrate, said layer remaining to serve as flexible diaphragms for piezoresistor bridge circuits formed in each of said diaphragms, forming a backing plate of semiconductor material including forming an oxide layer on the upper and lower surfaces of said backing plate, forming a mask in the oxide layer of the underside of the backing plate, said mask having spaced apart openings therein so as to be in alignment with the cavity regions in said substrate, etching away the semiconductor material in said openings such that a portion of a port is formed at each cavity region position, said etched ports stopping at the oxide layer formed on the upper surface of said backing plate, sealing the upper surface of said backing plate to said substrate under vacuum such that evacuated cavities are formed in said substrate, said cavities including said diaphragms as one wall of each cavity and said oxide layer in said ports serving as a portion of another wall of each cavity whereby absolute pressure sensor cavities are formed in the substrate, electrically testing the bridge circuits in the flexible diaphragms of the cavities, and thereafter converting said absolute pressure sensor cavities to ambient pressure sensor cavities by puncturing said oxide layers in said ports in said backing plate, thereby establishing a port opening into the associated cavity.