Method for producing a semiconductor strain sensitive element of an electromechanical semiconductor transducer

Claim 3

The method for producing a semiconductor strain sensitive element for electromechanical semiconductor transducers according to claim 1, wherein said semiconductor crystal layer comprises a semiconductor crystal of the opposite conductivity type to that of said base plate.

Claim 4

The method for producing a semiconductor strain sensitive element for electromechanical semiconductor transducers according to claim 1, wherein said semiconductor crystal layer comprises a semiconductor crystal having the same conductivity type as that of said base plate, the resistivity of said crystal layer being less than 0.001 of that of said base plate.

Claim 5

The method for producing a semiconductor strain sensitive element for electromechanical semiconductor transducers according to claim 1, further comprising the step of forming an electrical insulating film on the entire surface of said first and second narrow grooves and of said semiconductor crystal layer except for predetermined portions of said crystal layer upon which are formed said lead mounting electrodes, whereby said semiconductor strain sensitive element becomes covered with an electrical insulating film.

Claim 6

The method for producing a semiconductor strain sensitive element for electromechanical semiconductor transducers according to claim 1, further comprising the step of filling said first and second narrow grooves with an electrical insulating filler for reinforcing said semiconductor strain sensitive element.

Claim 7

The method for producing a semiconductor strain sensitive element for electromechanical semiconductor transducers according to claim 4, further comprising the step of filling said first and second narrow grooves with an electrical insulating filler for reinforcing said semiconductor strain sensitive element.

Claim 8

The method for producing a semiconductor strain sensitive element of electromechanical semiconductor transducers according to claim 1, wherein said semiconductor crystal utilized in said base plate and said layer comprises silicon.

Claim 9

The method for producing a semiconductor strain sensitive element for electromechanical semiconductor transducers according to claim 1, wherein said semiconductor crystal utIlized in said base plate and said layer comprises germanium.

Claim 10

The method for producing a semiconductor strain sensitive element for electromechanical semiconductor transducers according to claim 1, wherein said semiconductor crystal utilized in said base plate and said layer comprises gallium arsenide.

Claim 11

The method for producing a semiconductor strain sensitive element for electromechanical semiconductor transducers according to claim 1, wherein said semiconductor crystal layer is formed on the entire surface of at least one of the faces of said base plate by an epitaxial growth method.

Claim 12

The method for producing a semiconductor strain sensitive element for electromechanical semiconductor transducers according to claim 1, wherein said semiconductor crystal layer is formed on the entire surface of at least one of the faces of said base plate by a diffusion method.

Claim 13

The method for producing a semiconductor strain sensitive element for electromechanical semiconductor transducers according to claim 1, wherein said semiconductor crystal layer is formed on the entire surface of at least one of the faces of said base plate by an ion implantation method.

Claim 14

The method for producing a semiconductor strain sensitive element for electromechanical semiconductor transducers according to claim 1, wherein said first and second narrow grooves at said first and second predetermined portions in said layer are formed by a photoetching method.

Claim 15

The method for producing a semiconductor strain sensitive element for electromechanical semiconductor transducers according to claim 1, wherein said step of forming said first and second narrow grooves at said first and second predetermined portions in said layer is performed by employing a laser beam or an electron beam.

Claim 16

The method for producing a semiconductor strain sensitive element for electromechanical semiconductor transducers according to claim 4, wherein said step of forming said electrical insulating film comprises a thermal oxidation method.

Claim 17

The method for producing a semiconductor strain sensitive element for electromechanical semiconductor transducers according to claim 4, wherein said step of forming said electrical insulating film by a vacuum evaporation method.

Claim 18

The method for producing a semiconductor strain sensitive element of electromechanical semiconductor transducers according to claim 2, wherein: said semiconductor crystal utilized in said base plate and said layer comprises silicon; said silicon crystal layer is formed on said base plate by an epitaxial growth method; said first and second narrow grooves are formed in approximately straight lines at said first and second predetermined portions in said layer by a photo-etching method; and further comprising the step of forming an electrical insulating film on the entire surfaces of said first and second narrow grooves and of said semiconductor crystal layer, except for predetermined portions of said layer utilized for forming said lead mounting electrodes, by a vacuum evaporation method, whereby said semiconductor strain sensitive element becomes covered with said electrical insulating film.

Claim 19

The method for producing a semiconductor strain sensitive element for electromechanical semiconductor transducers according to claim 17, wherein said step of forming a layer of a semiconductor crystal comprises the steps of: a. slicing a block comprising an N-type silicon single crystal to obtain a wafer of the (110) crystallographic plane; b. processing the surface of said wafer into a mirror finish by lapping and polishing said wafer and then washing the surface thereof with pure water and then drying the same; and c. heating said N-type silicon base in a gas mixture comprising hydrogen (H2), silicon tetrachloride (SiCl4) and diborane (B2H6) at a temperature of about 1200*C for 1 to 10 minutes to thereby epitaxially grow a thin layer of uNiform thickness (about 1 Mu ) comprising P-type silicon on the entire surface of one of said faces of said N-type silicon base; and wherein said step of forming grooves comprises the steps of: d. coating a photo-resist on the entire surface of said P-type silicon layer; placing a photomask having predetermined transparent parts and opaque parts over said photo-resist; developing said photo-resist by exposure to ultraviolet rays from the upper side of the photomask for 10 to 30 seconds; removing the portion of said photo-resist corresponding to said straight narrow grooves from said P-type silicon layer, the longitudinal direction of said straight narrow grooves being parallel to the (110) direction of said layer; etching said P-type silicon layer and a part of said N-type silicon base, where said photo-resist was removed, to the depth of the desired groove (about 2 Mu ) with an etching solution comprising HNO3-HF; and removing the remainder of said photo-resist from said semiconductor layer with a dense sulfuric acid and then washing and drying said wafer; to thereby form said straight narrow grooves which are concave in cross section and extend over the surface of said semiconductor layer, and said strain sensitive parts, signal transmitting parts and perimeter part which are divided by means of said straight narrow grooves; and wherein said step of forming a layer of metal comprises the steps of: e. forming aluminum evaporated films on said predetermined portions of said signal transmitting parts by a vacuum evaporation method employing a metallic mask having four openings which determines said predetermined portions; and heating said strain sensitive element provided with said evaporated films in nitrogen gas at a temperature of 450*C to 550*C for 10 to 20 minutes; to thereby form said lead mounting electrodes on said predetermined portions of said signal transmitting parts.

Claim 20

The method for producing a semiconductor strain sensitive element for electromechanical semiconductor transducers according to claim 3, wherein: said semiconductor crystal utilized in said base plate and said layer comprises silicon; said silicon crystal layer is formed on said base plate by an epitaxial growth method; said first and second narrow grooves are formed in approximately straight lines at said first and second predetermined portions in said layer by a photo-etching method; and further comprising the step of forming an electrical insulating film on the entire surfaces of said first and second narrow grooves and of said semiconductor crystal layer, except for predetermined portions of said layer utilized for forming said lead mounting electrodes, by a vacuum evaporation method, whereby said semiconductor strain sensitive element becomes with the said covered electrical insulating film.

Claim 21

The method for producing a semiconductor strain sensitive element for electromechanical semiconductor transducers according to claim 19, wherein said step of forming a layer of a semiconductor crystal comprises the steps of: a. slicing a block comprising an N-type silicon single crystal to obtain a wafer of the (110) crystallographic plane; b. processing the surface of said wafer into a mirror finish by lapping and polishing said wafer and then by washing the surface thereof with pure water and then drying the same; c. epitaxially growing a thin layer of uniform thickness (about 1 Mu ) of N -type silicon on the entire surface of one face of said N-type silicon base by heating said N-type silicon base at a temperature of about 1200*C for 1 to 10 minutes in a gas mixture comprising hydrogen (H2), silicon tetrachloride (SiCl4) and phosphine (PH3), the resistivity of said epitaxial layer being about 0.0002 of that of said base; and wherein said steP of forming grooves comprises the steps of: d. coating a photo-resist on the entire N -type silicon layer; placing a photomask having a predetermined transparent parts and opaque parts over said photo-resist; developing said photo-resist by exposure to ultraviolet rays from the upper side of said photomask for 10 to 30 seconds; removing the portion of said photo-resist corresponding to said straight narrow grooves from said N -type silicon layer, the longitudinal direction of said straight narrow grooves being parallel to the (100) direction of said layer; etching said N -type silicon layer and a part of said N-type silicon base, where said photo-resist was removed, to the depth of the desired groove (about 2 Mu ) with an etching solution comprising HNO3-HF; and removing the remainder of said photo-resist from said semiconductor layer with a dense sulfuric acid and then washing and drying said wafer; to thereby form said straight narrow grooves which are concave in cross section and extend over the surface of said semiconductor layer and to form said strain sensitive parts, signal transmitting parts and perimeter part which are divided by means of said straight narrow grooves, and wherein said step of forming a layer of metal comprises the steps of: e. forming aluminum evaporated films on said predetermined portions of said signal transmitting parts by a vacuum evaporation method employing a metallic mask having four openings corresponding to said predetermined portions; and heating said strain sensitive element provided with said evaporated films in nitrogen gas at a temperature of 450*C to 550*C for 10 to 20 minutes; to thereby form said lead mounting electrodes on said predetermined portions of said signal transmitting parts.

Claim 22

The method for producing a semiconductor strain sensitive element for electromechanical semiconductor transducers according to claim 4, wherein said semiconductor crystal utilized in said base plate and said layer comprises silicon.

Claim 23

The method for producing a semiconductor strain sensitive element for electromechanical semiconductor transducers according to claim 21, wherein said silicon crystal layer comprises a semiconductor crystal having the opposite conductivity type to that of said base.

Claim 24

The method for producing a semiconductor strain sensitive element for electromechanical semiconductor transducers according to claim 22, wherein said semiconductor crystal layer is formed on the entire surface of at least one of the faces of said base plate by a diffusion method.

Claim 25

The method for producing a semiconductor strain sensitive element for electromechanical semiconductor transducers according to claim 23, wherein said first and second narrow grooves are formed in approximately straight lines at said first and second predetermined portions in said layer by a photo-etching method.

Claim 26

The method for producing a semiconductor strain sensitive element for electromechanical semiconductor transducers according to claim 24, wherein said electrical insulating film is formed by a thermal oxidation method.

Claim 27

The method for producing a semiconductor strain sensitive element for electromechanical semiconductor transducers according to claim 25, which includes the following steps: a. slicing a block comprising an N-type silicon single crystal to obtain a wafer of the (110) crystallographic plane; b. processing the surface of said wafer into a mirror finish by lapping and polishing said wafer and then by washing the surface thereof with pure water and then drying the same; c. heating said N-type silicon base at a temperature of 1000*C to 1200*C in a gas mixture comprising oxygen (O2), nitrogen (N2) and diborane (B2H6) for 20 to 60 minutes to uniformly diffuse boron on the entire surface of both faces oF said base to thereby form a thin diffused layer of uniform thickness (about 1 Mu ) of P-type silicon; d. coating a photo-resist on the entire P-type silicon layer; placing a photomask having predetermined transparent parts and opaque parts over said photo-resist; developing said photo-resist by exposure to ultraviolet rays from the upper side of said photomask for 10 to 30 seconds; removing the portion of said photo-resist corresponding to said straight narrow grooves from said P-type silicon layer; etching said P-type silicon layer and a part of said N-type silicon base, where said photo-resist was removed, to the depth of the desired groove (about 2 Mu ) with an etching solution comprising HNO3-HF; removing the remainder of said photo-resist from said semiconductor layer with a dense sulfuric acid, and then washing and drying said wafer to thereby form said straight narrow grooves which are concave in cross section and extend over the surface of said semiconductor layer and to form said strain sensitive parts, signal transmitting parts and perimeter part which are divided by means of said straight narrow grooves; de1. heating said semiconductor strain sensitive element at a temperature of approximately 1000*C for approximately 30 minutes in a saturated vapor steam in order to form a silicon oxide film (the thickness thereof being approximately several thousand A) on the entire surfaces of said layer and said straight narrow grooves; de2. removing predetermined portions of said silicon oxide film corresponding to lead mounting electrodes to be formed hereafter by a selective etching method employing a photo-resist; e. forming aluminum evaporated films on said predetermined portions where said silicon oxide film was removed, by a vacuum evaporation method employing a metallic mask having four openings corresponding to said predetermined portions; and heating said strain sensitive element provided with said evaporated films in nitrogen gas at a temperature of 450*C to 550*C for 10 to 20 minutes to thereby form said lead mounting electrodes on said predetermined portions of said signal transmitting parts.

Claim 28

The method for producing a semiconductor strain sensitive element for electromechanical semiconductor transducers according to claim 5, wherein; said semiconductor crystal utilized in said base plate and said layer comprises silicon; said semiconductor crystal layer comprises a semiconductor crystal of the opposite conductivity type to that of said base; said silicon crystal layer is formed on said base plate by an epitaxial growth method; said first and second narrow grooves are formed in approximately straight lines at predetermined portions in said layer by a photo-etching method; and said electrical insulating filler comprises an epoxy resin.

Claim 29

The method for producing a semiconductor strain sensitive element for electromechanical semiconductor transducers according to claim 27, which includes the following steps: a. slicing a block comprising an N-type silicon single crystal to obtain a wafer of the (110) crystallographic plane; b. processing the surface of said wafer into a mirror finish by lapping and polishing said wafer and then washing the surface thereof with pure water and then drying the same; c. heating the N-type silicon base in a gas mixture comprising hydrogen (H2), silicon tetrachloride (SiCl4) and diborane (B2H6) at a temperature of approximately 1200*C for 1 to 10 minutes to thereby epitaxially grow a thin layer of uniform thickness (about 1 Mu ) comprising P-type silicon on the entire surface of one of the faces of said N-type silicon base; d. coating a photo-resist on the entire P-type silicon layer; placing a photomask having predetermined transparent parts and opaque paRts over said photo-resist; developing said photo-resist by exposure to ultraviolet rays from the upper side of said photomask for 10 to 30 seconds; removing the portion of said photo-resist corresponding to said straight narrow grooves from said P-type silicon layer; etching said P-type silicon layer and a part of said N-type silicon base where said photo-resist was removed, to the depth of the desired groove (about 2 Mu ) with an etching solution comprising HNO3-HF; removing the remainder of said photo-resist from said semiconductor layer with a dense sulfuric acid and then washing and drying the entire wafer to thereby form said straight narrow grooves which are concave in cross section and extend over the surface of said semiconductor layer, and to form said strain sensitive parts, signal transmitting parts and perimeter part which are divided by means of said straight narrow grooves; e. forming aluminum evaporated films on said predetermined portions of said signal transmitting parts by a vacuum evaporation method employing a metallic mask having four openings corresponding to said predetermined portions; heating said strain sensitive element provided with said evaporated films in nitrogen gas at a temperature of 450*C to 550*C for 10 to 20 minutes to thereby form said lead mounting electrodes on said predetermined portions of said signal transmitting parts, f. providing an adhesive such as an epoxy resin on said P-type silicon layer of said semiconductor strain sensitive element; and forcing said adhesive into said narrow grooves by spinning said element at a speed of a few hundred rpm to thereby fill said narrow grooves with said adhesive.