Method and apparatus for testing the doping concentration of semiconductors

Claim 3

The method of testing the doping concentration below the surface of a semiconductor body as defined in claim 1 and which includes the further step of storing the value of the reflected light together with the co-ordinate of said relative movement between said light beam and semiconductor body.

Claim 4

Apparatus for testing the doping concentration below the surface of a semiconductor body having opposite parallel faces which comprises: means for producing and directing a beam of monochromatic light against a portion of the surface of one face of the semiconductor body to be tested for reflection therefrom, means including electrode means applied at the opposite faces of the semiconductor body and a source of alternating voltage for producing an electric field within the semiconductor body perpendicular to the face to be tested, means for effecting relative movement between the semiconductor body and the incident light beam in a direction perpendicular to the beam, detector means for detecting the monochromatic light reflected from correspondingly different surface portions of the semiconductor body, and means for measuring the output from the detector means and which is indicative of the doping concentration existing below the different surface portions of the semiconductor body.

Claim 5

Apparatus for testing the doping concentration below the surface of a semiconductor body having opposite parallel faces which comprises: means for producing and directing a beam of monochromatic light against a portion of the surface of one face of the semiconductor body to be tested for reflection therefrom, means including electrode means applied at the opposite faces of the semiconductor body and a source of alternating voltage for producing an electric field within the semiconductor body perpendicular to the face to be tested, means for effecting relative movement between the semiconductor body and the incident light beam in a direction perpendicular to the beam, detector means for detecting the monochromatic light reflected from correspondingly different surface portions of the semiconductor body, and means for measuring the output from the detector means and which is indicative of the doping concentration existing below the different surface portions of the semiconductor body.

Claim 6

Apparatus for testing the doping concentration below the surface of a semiconductor body as defined in claim 3 wherein said electrode means includes a transparent conductive layer applied to the face of the semiconductor body receiving the light beam for reflection therefrom and a conductive contact layer applied to the opposite face.

Claim 7

Apparatus for testing the doping concentration below the surface of a semiconductor body as defined in claim 4 wherein said transparent conductive layer is constituted by a layer of tindioxide having a thickness between 0.05 Mu m and 0.5 Mu m and preferably about 0.1 Mu m.

Claim 8

Apparatus for testing the doping concentration below the surface of a semiconductor body as defined in claim 3 wherein said electrode means includes an at least partially transparent conductive electrode member arranged adjacent to but spaced from the face of the semiconductor body receiving the light beam for reflection therefrom and a conductive contact layer applied to the opposite face.

Claim 9

Apparatus for testing the doping concentration below the surface of a semiconductor body as defined in claim 6 and wherein the space between said at least partially transparent conductive electrode member and the face of the semiconductor body is evacuated.

Claim 10

Apparatus for testing the doping concentration below the surface of a semiconductor body as defined in claim 7 wherein said at least partially transparent conductive electrode member and the face of the semiconductor body receiving the light beam for reflection therefrom is located within an evacuated chamber.

Claim 11

Apparatus for testing the doping concentration below the surface of a semiconductor body as defined in claim 6 wherein said at least partially transparent conductive electrode member is constituted by a pin hole diaphragm.

Claim 12

Apparatus for testing the doping concentration below the surface of a semiconductor body as defined in claim 9 wherein the diameter of the pin hole in said diaphragm lies between 30 Mu m and 170 Mu m.

Claim 13

Apparatus for testing the doping concentration below the surface of a semiconductor body as defined in claim 6 wherein said at least partially transparent conductive electrode member is constituted by at least one set of parallel spaced wires.

Claim 14

Apparatus for testing the doping concentration below the surface of a semiconductor body as defined in Claim 6 wherein said at least partially transparent conductive electrode member is constituted by a wire grid.

Claim 15

Apparatus for testing the doping concentration below the surface of a semiconductor body as defined in claim 3 wherein said detector means for measuring the amount of the light reflected from the face of the semiconductor body comprises a photomultiplier.

Claim 16

Apparatus for testing the doping concentration below the surface of a semiconductor body as defined in claim 13 and which further includes means connected to said photomultiplier for regulating the direct current component of the output therefrom to a constant value.

Claim 17

Apparatus for testing the doping concentration below the surface of a semiconductor body as defined in claim 13 and which includes a phase-responsive amplifier connected to the output of said photomultiplier for intensifying the alternating current component thereof, said phase-responsive amplifier being provided with a reference signal obtained from said source of alternating voltage which produces the electric field within the semiconductor body.

Claim 18

Apparatus for testing the doping concentration below the surface of a semiconductor body as defined in claim 15 and which further includes a recording device connected to the output of said phase-responsive amplifier.

Claim 19

Apparatus for testing the doping concentration below the surface of a semiconductor body as defined in claim 15 and which further includes a recording device in the form of an XY coordinate printer, one of said coordinates being controlled by the output from said phase-responsive amplifier, means for driving said semiconductor body along a path perpendicular to the incident light falling on the face of the semiconductor body being tested, and a path indicator connected to said driving means and which serves to control the other coordinate of said printer.

Claim 20

Apparatus for testing the doping concentration existing below the surface of a semiconductor body as defined in claim 3 wherein said means for producing said monochromatic light beam comprises an xenon lamp followed by a monochromator.

Claim 21

Apparatus for testing the doping concentration existing below the surface of a semiconductor body as defined in claim 3 wherein said means for producing said monochromatic light beam comprises a spectrum line.

Claim 22

Apparatus for testing the doping concentration existing below the surface of a semiconductor body as defined in claim 3 wherein said means for producing said monochromatic light beam comprises a laser and which is preferably tunable.

Claim 23

Apparatus for testing the doping concentration existing below the surface of a semiconductor body as defined in claim 3 wherein said source of alternating voltage utilized for producing said electric field within the semiconductor body operates at frequency of from 100 to 500 Hz.