Method for making schottky barrier diodes

Claim 3

The method as recited in claim 1 wherein prior to forming the layer of the Schottky metal adjacent the oxide layer a conductivity type imparting impurity concentration for the principal surface of the substrate is selected by ion implanting a known amount of impurities into the principal surface.

Claim 4

The method as recited in claim 1 wherein prior to forming the layer of Schottky metal adjacent the oxide layer a conductivity type imparting impurity concentration for the principal surface of the substrate is selected by diffusing a known amount of the impurities into the principal surface.

Claim 5

The method as recited in claim 3 wherein the impurities are diffused from a doped oxide adjacent the principal surface.

Claim 6

The method as recited in claim 1 wherein the Schottky metal is platinum.

Claim 7

In a method for making a plurality of Schottky barrier diodes comprising the steps of: preselecting a Schottky barrier height, φ b ; selecting a first amount of a Schottky metal; placing the first selected amount of the Schottky metal above a principal surface of a first silicon substrate; alloying the Schottky metal to the first substrate wherein a first Schottky metal silicide layer is formed adjacent the first substrate having a first barrier height; selecting a second amount of a Schottky metal; placing the second selected amount of the Schottky metal above a principal surface of a second silicon substrate having a second barrier height; the improvement comprising the additional steps of: forming conductivity type imparting impurity atoms of a selected free carrier concentration equally on the principal surfaces of the first and second substrates; forming similar thin layers of a natural oxide of silicon adjacent the principal surfaces of the first and second silicon substrates prior to the placement of the Schottky metal above said principal surfaces; selecting and using a first time duration for alloying the Schottky metal to the first substrate; determining the actual barrier height of the first Schottky metal silicide layer; and selecting and using a second time duration for alloying the Schottky metal to the ground substrate determined by an equation t' = kφ b n /N o where t' is the second time duration, N o is the concentration of the impurity atoms at the principal surfaces, n is equal to 4 for platinum as the Schottky metal, and k is a constant determined by the above equation wherein the actual barrier height for the first metal silicon layer is substituted for the preselected barrier height, φ b .

Claim 8

In a method for making a plurality of Schottky barrier diodes comprising the steps of: preselecting a Schottky barrier height, φ b ; selecting a first amount of a Schottky metal; placing the first selected amount of the Schottky metal above a principal surface of a first silicon substrate; alloying the Schottky metal to the first substrate wherein a first Schottky metal silicide layer is formed adjacent the first substrate having a first barrier height; selecting a second amount of a Schottky metal; placing the second selected amount of the Schottky metal above a principal surface of a second silicon substrate having a second barrier height; the improvement comprising the additional steps of: forming conductivity type imparting impurity atoms of a selected free carrier concentration equally on the principal surfaces of the first and second substrates; forming similar thin layers of a natural oxide of silicon adjacent the principal surfaces of the first and second silicon substrates prior to the placement of the Schottky metal above said principal surfaces; selecting and using a first time duration for alloying the Schottky metal to the first substrate; determining the actual barrier height of the first Schottky metal silicide layer; and selecting and using a second time duration for alloying the Schottky metal to the ground substrate determined by an equation t' = kφ b n /N o where t' is the second time duration, N o is the concentration of the impurity atoms at the principal surfaces, n is equal to 4 for platinum as the Schottky metal, and k is a constant determined by the above equation wherein the actual barrier height for the first metal silicon layer is substituted for the preselected barrier height, φ b .

Claim 9

The method of claim 6 wherein the Schottky metal is platinum.

Claim 10

The method of claim 6 wherein the impurity atoms of a selected concentration are formed by disposing a doped oxide of a known impurity concentration adjacent the principal surfaces and heating.

Claim 11

The method of claim 6 wherein the impurity atoms of a selected concentration are formed by ion implanting like ions of a known flux density into the principal surfaces.