Method of making triple diffused ISL structure

Claim 1

A method of fabricating a semiconductive structure from a monocrystalline semiconductor substrate of first type conductivity, the method comprising the steps of: forming a first region of second type conductivity opposite to the first type conductivity in the substrate along an upper surface thereof by the steps of (1) introducing a first impurity of second type conductivity into the substrate to form a major portion of the first region and (2) introducing a second impurity of second type conductivity into the substrate to form a minor portion of the first region contiguous with the major portion but having a lower net impurity concentration than the major portion and extending considerably less than it below the upper surface; introducing an impurity of first type conductivity into the substrate to form a second region of first type conductivity inside the location for semiconductive boundary of the first region, the second region extending into the locations for both the major and minor portions to a depth less than that of the minor portion; introducing an impurity of second type conductivity into the substrate to form a third region of second type conductivity inside the location for the semiconductive boundary of the second region laterally spaced apart from the location for the minor portion; and depositing metallic material on the substrate to form at least one Schottky rectifying contact with the major portion outside the second region, an ohmic contact with the third region, an ohmic contact with the second region outside the third region, and an ohmic contact with the substrate outside the first region.

Claim 2

A method of fabricating a semiconductive structure from a monocrystalline semiconductor substrate of first type conductivity, the method comprising the steps of: forming a first region of second type conductivity opposite to the first type conductivity in the substrate along an upper surface thereof by the steps of (1) introducing a first impurity of second type conductivity into the substrate to form a major portion of the first region and (2) introducing a second impurity of second type conductivity into the substrate to form a minor portion of the first region contiguous with the major portion but having a lower net impurity concentration than the major portion and extending considerably less than it below the upper surface; introducing an impurity of first type conductivity into the substrate to form a second region of first type conductivity inside the location for semiconductive boundary of the first region, the second region extending into the locations for both the major and minor portions to a depth less than that of the minor portion; introducing an impurity of second type conductivity into the substrate to form a third region of second type conductivity inside the location for the semiconductive boundary of the second region laterally spaced apart from the location for the minor portion; and depositing metallic material on the substrate to form at least one Schottky rectifying contact with the major portion outside the second region, an ohmic contact with the third region, an ohmic contact with the second region outside the third region, and an ohmic contact with the substrate outside the first region.