Diffusion control in semiconductive bodies

Claim 1

A METHOD OF FABRICATING SEMICONDUCTOR DEVICES EXHIBITING FAST SWITCHING RATES AND RELATIVELY HIGH BREAKDOWN VOLTAGES COMPRISING THE STEPS OF FORMING ON AT LEAST A PORTION OF A SEMICONDUCTOR BODY A FIRST OXIDE LAYER PERMIEABLE TO DIFFUSION THERETHROUGH OF A FIRST IMPURITY MATERIAL AND IMPERMEABLE TO DIFFUSION THERETHROUGH OF A SECOND DIFFERENT IMPURITY MATERIAL, DIFFUSING THE FIRST IMPURITY MATERIAL THROUGH SAID FIRST LAYER INTO THE BODY AT A FIRST PREDETERMINED TEMPERATURE TO FORM A FIRST DIFFUSED ZONE EXHIBITING A DESIRED AND PERMANENT DEGREE OF SURFACE IMPURITY CONCENTRATION, REMOVING AT LEAST ONE DISCRETE PORTION OF THE FIRST LAYER FROM THE SURFACE OF SAID BODY, DIFFUSING A SECOND IMPURITY MATERIAL AT A SECOND PREDETERMINED TEMPERATURE INTO SAID BODY WHERE THE FIRST LAYER HAS BEEN REMOVED, THEREBY FORMING A SECOND DIFFUSED ZONE EXHIBITING A DESIRED AND PERMANENT DEGREE OF SURFACE IMPURITY CONCENTRATION, REMOVING THE ENTIRE FIRST OXIDE LAYER, EVAPORATING AND DEPOSITING A NOBLE METAL ON AT LEAST A PART OF A PREVIOUSLY UNDIFFUSED SURFACE AREA OF SAID BODY AT A THIRD TEMPERATURE WHICH NEITHER APPRECIABLY ALTERS THE SURFACE IMPURITY CONCENTRATION OR CAUSES OUTDIFFUSION OF AT LEAST SAID SECOND IMPURITY MATERIAL, APPLYING A SECOND IMPERMEABLE OXIDE LAYER OVER AT LEAST SAID ZONE WITH A SECOND DIFFUSED IMPURITY AND APPRECIABLE ALTERATION OF THE SURFACE IMPURITY CONCENTRATION THEREOF WHEN SAID BODY IS HEATED TO A FOURTH PREDETERMINED TEMPERATURE TO DIFFUSE SAID NOBLE METAL INTO THE PREVIOUSLY UNDIFFUSED SURFACE AREA OF SAID BODY TO A DEPTH AND SURFACE CONCENTRATION NECESSARY TO OBTAIN A HIGH SWITCHING RATE FOR SAID DEVICE.

Claim 2

A METHOD OF FABRICATING SEMICONDUCTOR DEVICES EXHIBITING FAST SWITCHING RATES AND RELATIVELY HIGH BREAKDOWN VOLTAGES COMPRISING THE STEPS OF FORMING ON AT LEAST A PORTION OF A SEMICONDUCTOR BODY A FIRST OXIDE LAYER PERMIEABLE TO DIFFUSION THERETHROUGH OF A FIRST IMPURITY MATERIAL AND IMPERMEABLE TO DIFFUSION THERETHROUGH OF A SECOND DIFFERENT IMPURITY MATERIAL, DIFFUSING THE FIRST IMPURITY MATERIAL THROUGH SAID FIRST LAYER INTO THE BODY AT A FIRST PREDETERMINED TEMPERATURE TO FORM A FIRST DIFFUSED ZONE EXHIBITING A DESIRED AND PERMANENT DEGREE OF SURFACE IMPURITY CONCENTRATION, REMOVING AT LEAST ONE DISCRETE PORTION OF THE FIRST LAYER FROM THE SURFACE OF SAID BODY, DIFFUSING A SECOND IMPURITY MATERIAL AT A SECOND PREDETERMINED TEMPERATURE INTO SAID BODY WHERE THE FIRST LAYER HAS BEEN REMOVED, THEREBY FORMING A SECOND DIFFUSED ZONE EXHIBITING A DESIRED AND PERMANENT DEGREE OF SURFACE IMPURITY CONCENTRATION, REMOVING THE ENTIRE FIRST OXIDE LAYER, EVAPORATING AND DEPOSITING A NOBLE METAL ON AT LEAST A PART OF A PREVIOUSLY UNDIFFUSED SURFACE AREA OF SAID BODY AT A THIRD TEMPERATURE WHICH NEITHER APPRECIABLY ALTERS THE SURFACE IMPURITY CONCENTRATION OR CAUSES OUTDIFFUSION OF AT LEAST SAID SECOND IMPURITY MATERIAL, APPLYING A SECOND IMPERMEABLE OXIDE LAYER OVER AT LEAST SAID ZONE WITH A SECOND DIFFUSED IMPURITY AND APPRECIABLE ALTERATION OF THE SURFACE IMPURITY CONCENTRATION THEREOF WHEN SAID BODY IS HEATED TO A FOURTH PREDETERMINED TEMPERATURE TO DIFFUSE SAID NOBLE METAL INTO THE PREVIOUSLY UNDIFFUSED SURFACE AREA OF SAID BODY TO A DEPTH AND SURFACE CONCENTRATION NECESSARY TO OBTAIN A HIGH SWITCHING RATE FOR SAID DEVICE.