Semiconductor structure with sloped side walls and method

Claim 2

In a method for fabricating a structure on a surface of a semiconductor body of one conductivity type, providing a first layer of a first material having a first etch rate on the surface of the body, providing a second layer of a second material having a second etch rate on said first layer, forming an etch resistant mask over said second layer having a pattern of openings therein exposing areas of said second layer through said openings, applying an etch through said openings which attacks said first and second materials to form openings in said first layer exposing the surface of the semiconductor body and so that said openings are defined by side walls in the first layer having an angle of less than 70* with respect to said surface, removing said mask and said second layer of said second material, forming through at least one of said openings on said first layer a region of opposite conductivity type in said semiconductor body to thereby produce a PN junction in said semiconductor body and forming contact metallization in said openings and on said sloped side walls adjacent to said one opening whereby the thickness of the metallization is relatively uniform throughout.

Claim 3

A method as in claim 1 wherein the semiconductor body is formed of silicon, the first material is provided by thermally growing silicon dioxide and the second material is provided by vapor depositing silicon dioxide.

Claim 4

A method as in claim 2 wherein the vapor deposited oxide is grown to a thickness ranging from 200 to 2,000 A.

Claim 5

A method as in claim 1 wherein a desired slope can be obtained by varying the etch rate for the second material by doping the second material with impurities.

Claim 6

A method as in claim 1 wherein a desired slope can be obtained by doping the first named layer with an impurity.

Claim 7

A method as in claim 1 wherein the desired slope can be obtained by annealing the first layer of material after it has been formed.

Claim 8

A method as in claim 1 wherein said first material has an etch rate which is substantially less than the etch rate for the second material whereby in the formation of said openings, said second layer is etched away beneath said mask to form generally vertical side walls and wherein the side walls in the first layer extend downwardly and inwardly with respect to the surface.

Claim 9

A method as in claim 1 together with the step of forming a doped glass on said first layer after the openings have been formed in the first layer and extending into said openings, forming an additional layer of said second material on said doped glass, forming an etch resistant additional mask on said additional layer of said second material having a pattern of openings therein exposing said additional layer of said second material, applying an etch through the openings in the additional mask which attacks the first and second materials to form openings extending through said additional layer of said second material and through said doped glass and said first layer which are defined by side walls in said additional layer, said doped glass and said first layer extending at an angle of less than 70* with respect to said surface and removing said additional mask and said additional layer of said second material and wherein said metallization extends through the additional openings.

Claim 10

In a method for fabricating a structure on the surface of a semiconductor body of one Conductivity type, providing a first layer of a first material having a first etch rate on the surface of the body, providing a second layer of a second material having a second etch rate on said first layer, forming an etch resistant mask over said second layer having a pattern of openings therein exposing areas of said second layer through said openings, applying an etch through said openings which attacks said first and second materials to form openings in said first layer exposing the surface of the support body so that said openings are defined by side walls in the first layer at an angle of less than 70* with respect to said surface, removing said mask and said second layer of said second material, forming through at least one of said openings in said first layer a region of opposite conductivity in said semiconductor body to thereby produce a PN junction in said semiconductor body, forming a first additional layer of said second material upon said first layer, forming an additional mask on said first additional layer of said second material, providing additional openings in said additional mask in accordance with a predetermined pattern, applying an etch through said additional openings in said additional mask to form openings extending through said first additional layer of said second material and said first layer and exposing said surface, removing said additional mask and said additional layer of said second material, forming through at least one of said last named openings in said first layer a region of said one conductivity type, forming a second additional layer of said second material on said first layer of insulating material and extending into said last named openings, forming a second additional mask on said second additional layer of said second material having a pattern of openings therein, applying an etch through said last named pattern of openings to form contact openings extending through said second additional layer and through said first layer and so that the contact openings are defined by sloping side walls in the first layer having an angle less than 70* with respect to said surface, removing said second additional mask and said second additional layer of said second material and forming contact metallization extending through said contact openings to make contact with said semiconductor body and covering said side walls defining said contact openings so that the metallization has a relatively uniform thickness throughout.

Claim 11

In a method for fabricating a structure on the surface of a semiconductor body of one Conductivity type, providing a first layer of a first material having a first etch rate on the surface of the body, providing a second layer of a second material having a second etch rate on said first layer, forming an etch resistant mask over said second layer having a pattern of openings therein exposing areas of said second layer through said openings, applying an etch through said openings which attacks said first and second materials to form openings in said first layer exposing the surface of the support body so that said openings are defined by side walls in the first layer at an angle of less than 70* with respect to said surface, removing said mask and said second layer of said second material, forming through at least one of said openings in said first layer a region of opposite conductivity in said semiconductor body to thereby produce a PN junction in said semiconductor body, forming a first additional layer of said second material upon said first layer, forming an additional mask on said first additional layer of said second material, providing additional openings in said additional mask in accordance with a predetermined pattern, applying an etch through said additional openings in said additional mask to form openings extending through said first additional layer of said second material and said first layer and exposing said surface, removing said additional mask and said additional layer of said second material, forming through at least one of said last named openings in said first layer a region of said one conductivity type, forming a second additional layer of said second material on said first layer of insulating material and extending into said last named openings, forming a second additional mask on said second additional layer of said second material having a pattern of openings therein, applying an etch through said last named pattern of openings to form contact openings extending through said second additional layer and through said first layer and so that the contact openings are defined by sloping side walls in the first layer having an angle less than 70* with respect to said surface, removing said second additional mask and said second additional layer of said second material and forming contact metallization extending through said contact openings to make contact with said semiconductor body and covering said side walls defining said contact openings so that the metallization has a relatively uniform thickness throughout.

Claim 12

A method as in claim 9 wherein prior to the formation of the second additional layer of said second material, a layer of doped glass is formed on said first layer.

Claim 13

A method as in claim 9 wherein said first material has an etch rate which is substantially less than the etch rate for the second material whereby in the formation of said openings, said second layer is etched away beneath said mask to form generally vertical side walls and wherein said side walls forming the openings in said first layer extend downwardly and inwardly with respect to said surface.

Claim 14

A method as in claim 9 wherein the first material is provided by thermally growing the same and wherein the second material is provided by vapor depositing the same.

Claim 15

A method as in claim 12 wherein the first and second materials are silicon dioxide.