Method of making a semiconductor device having improved pn junction avalanche characteristics

Claim 1

A METHOD OF MAKING A RECTIFYING JUNCTION IN A SEMICONDUCTOR BODY SO THAT AVALANCHE BREAKDOWN OF SAID JUNCTION TENDS TO OCCUR BENEATH THE SURFACE OF SAID BODY, SAID METHOD COMPRISING, EPITAXIALLY GROWING ON A SURFACE OF A SEMICONDUCTOR CRYSTAL OF ONE CONDUCTIVITY TYPE A SEMICONDUCTOR LAYER OF THE SAME CONDUCTIVITY TYPE AS SAID CRYSTAL BUT OF HIGHER RESISTIVITY THAN THE UNDERLYING CRYSTAL MATERIAL, AND SELECTIVELY DIFFUSING AN IMPURITY OF OPPOSITE CONDUCTIVITY TYPE TO FORM A SEMICONDUCTOR REGION EXTENDING THROUGH ONLY A PORTION OF SAID LAYER TO DEFINE A RECTIFYING JUNCTION EXTENDING FROM BENEATH SAID LAYER TO FORM A REGION OF OPPOSITE CONDUCTIVITY SEMICONDUCTOR MATERIAL DEFINING A RECTIFYING JUNCTION WHICH EXTENDS CONTINUOUSLY WITHIN THE BULK OF SAID CRYSTAL AND BETWEEN SAID OPPOSITE CONDUCTIVITY REGION AND SAID SEMICONDUCTOR CRYSTAL AND THROUGH SAID SEMICONDUCTOR SURFACE LAYER OF HIGHER RESISTIVITY TO THE SURFACE OF SAID BODY WHEREBY THE PORTION OF SAID RECTIFYING JUNCTION BOUNDED BY SAID UNDERLYING SEMICONDUCTOR CRYSTAL OF SAID ONE CONDUCTIVITY TYPE AND BY SAID OPPOSITE CONDUCTIVITY REGION WILL BREAK DOWN AT A LOWER REVERSE VOLTAGE THAN THE PORTION OF SAID RECTIFYING JUNCTION BOUNDED BY SAID SEMICONDUCTOR SURFACE LAYER OF HIGHER RESISTIVITY.

Claim 2

A METHOD OF MAKING A RECTIFYING JUNCTION IN A SEMICONDUCTOR BODY SO THAT AVALANCHE BREAKDOWN OF SAID JUNCTION TENDS TO OCCUR BENEATH THE SURFACE OF SAID BODY, SAID METHOD COMPRISING, EPITAXIALLY GROWING ON A SURFACE OF A SEMICONDUCTOR CRYSTAL OF ONE CONDUCTIVITY TYPE A SEMICONDUCTOR LAYER OF THE SAME CONDUCTIVITY TYPE AS SAID CRYSTAL BUT OF HIGHER RESISTIVITY THAN THE UNDERLYING CRYSTAL MATERIAL, AND SELECTIVELY DIFFUSING AN IMPURITY OF OPPOSITE CONDUCTIVITY TYPE TO FORM A SEMICONDUCTOR REGION EXTENDING THROUGH ONLY A PORTION OF SAID LAYER TO DEFINE A RECTIFYING JUNCTION EXTENDING FROM BENEATH SAID LAYER TO FORM A REGION OF OPPOSITE CONDUCTIVITY SEMICONDUCTOR MATERIAL DEFINING A RECTIFYING JUNCTION WHICH EXTENDS CONTINUOUSLY WITHIN THE BULK OF SAID CRYSTAL AND BETWEEN SAID OPPOSITE CONDUCTIVITY REGION AND SAID SEMICONDUCTOR CRYSTAL AND THROUGH SAID SEMICONDUCTOR SURFACE LAYER OF HIGHER RESISTIVITY TO THE SURFACE OF SAID BODY WHEREBY THE PORTION OF SAID RECTIFYING JUNCTION BOUNDED BY SAID UNDERLYING SEMICONDUCTOR CRYSTAL OF SAID ONE CONDUCTIVITY TYPE AND BY SAID OPPOSITE CONDUCTIVITY REGION WILL BREAK DOWN AT A LOWER REVERSE VOLTAGE THAN THE PORTION OF SAID RECTIFYING JUNCTION BOUNDED BY SAID SEMICONDUCTOR SURFACE LAYER OF HIGHER RESISTIVITY.