Abstract A method of making semiconductor devices using selective impurity diffusion techniques. A dopant layer of a first conductivity type is formed on a semiconductor body of a second conductivity type. A patterned photoresist layer is formed on the dopant layer to mask portions thereof, and an etchant is used to remove the exposed area of the dopant layer in the unmasked areas, exposing the semiconductor body thereat. A thin layer of the semiconductor body is removed at the exposed areas by being subjected to a plasma etchant in a plasma reactor. The photoresist is removed by substituting oxygen for the plasma etchant in the plasma reactor. The semiconductor is then heated to diffuse a region of said second conductivity type into the semiconductor. A protective oxide coating may be provided on the exposed silicon prior to the diffusion step to prevent autodoping. The protective oxide coating and the dopant layer are removed. The delineation provided by the plasma etching step may be used as an aid in subsequent mask alignment steps.
A METHOD FOR MAKING A SEMICONDUCTOR DEVICE COMPRISING THE STEPS OF: DEPOSITING A FIRST LAYER OF A DOPED OXIDE OF SILICON OF A SECOND CONDUCTIVITY TYPE ON A SURFACE OF A BODY OF SILICON OF A FIRST CONDUCTIVITY TYPE, FORMING A FIRST LAYER OF PHOTORESIST ON SAID FIRST LAYER OF DOPED OXIDE OF SILICON, SAID LAYER OF PHOTORESIST BEING PATTERNED TO EXPOSE THE SURFACE OF SAID FIRST LAYER OF DOPED OXIDE OF SILICON, SUBJECTING SAID EXPOSED SURFACE TO A FIRST ETCHANT AND REMOVING SAID EXPOSED SURFACE OF SAID FIRST LAYER OF DOPED OXIDE OF SILICON THEREBY EXPOSING SAID SURFACE OF SAID BODY OF SILICON, SUBJECTING SAID EXPOSED SURFACE OF SAID BODY OF SILICON AND SAID FIRST LAYER OF PHOTORESIST TO A PLASMA ETCHANT IN A REACTOR FOR SELECTIVELY REMOVING IN SEQUENCE A PREDETERMINED THICKNESS OF MATERIAL FROM SAID EXPOSED SILICON SURFACE TO DELINEATE THE REGION OF SAID BODY OF SILION BENEATH SAID FIRST LAYER OF DEPED OXIDE OF SILICON AND SAID FIRST LAYER OF PHOTORESIST, AND HEATING SAID BODY OF SILICON TO DIFFUSE DOPING IMPURITES FROM SAID FIRST LAYER OF DOPED OXIDE OF SILICON INTO SAID BODY OF SILICON TO FORM A REGION OF SAID SECOND CONDUCTIVITY TYPE THEREIN.
Claim 2
Independent Claim
199 words
A METHOD FOR MAKING A SEMICONDUCTOR DEVICE COMPRISING THE STEPS OF: DEPOSITING A FIRST LAYER OF A DOPED OXIDE OF SILICON OF A SECOND CONDUCTIVITY TYPE ON A SURFACE OF A BODY OF SILICON OF A FIRST CONDUCTIVITY TYPE, FORMING A FIRST LAYER OF PHOTORESIST ON SAID FIRST LAYER OF DOPED OXIDE OF SILICON, SAID LAYER OF PHOTORESIST BEING PATTERNED TO EXPOSE THE SURFACE OF SAID FIRST LAYER OF DOPED OXIDE OF SILICON, SUBJECTING SAID EXPOSED SURFACE TO A FIRST ETCHANT AND REMOVING SAID EXPOSED SURFACE OF SAID FIRST LAYER OF DOPED OXIDE OF SILICON THEREBY EXPOSING SAID SURFACE OF SAID BODY OF SILICON, SUBJECTING SAID EXPOSED SURFACE OF SAID BODY OF SILICON AND SAID FIRST LAYER OF PHOTORESIST TO A PLASMA ETCHANT IN A REACTOR FOR SELECTIVELY REMOVING IN SEQUENCE A PREDETERMINED THICKNESS OF MATERIAL FROM SAID EXPOSED SILICON SURFACE TO DELINEATE THE REGION OF SAID BODY OF SILION BENEATH SAID FIRST LAYER OF DEPED OXIDE OF SILICON AND SAID FIRST LAYER OF PHOTORESIST, AND HEATING SAID BODY OF SILICON TO DIFFUSE DOPING IMPURITES FROM SAID FIRST LAYER OF DOPED OXIDE OF SILICON INTO SAID BODY OF SILICON TO FORM A REGION OF SAID SECOND CONDUCTIVITY TYPE THEREIN.
Claim 3
Dependent Claim
20 words
The method as recited in claim 1 wherein said first conductivity type is P-type and said second conductivity is N-type.
Claim 4
Dependent Claim
17 words
The method as recited in claim 2 wherein said plasma etchant is carbon tetrafluoride followed by oxygen.
Claim 5
Dependent Claim
39 words
The method as recited in claim 2 including the step of forming a first layer of undoped oxide of silicon to protect against autodoping on said body of silicon after exposing said body of silicon to said plasma etchant.
Claim 6
Dependent Claim
18 words
The method as recited in claim 2 wherein said predetermined thickness is between 50 and 300 angstrom units.