Real-time in-line testing of semiconductor wafers
An apparatus and method for the real-time, in-line testing of semiconductor wafers during the manufacturing process. In one embodiment the apparatus includes a probe assembly within a semiconductor wafer processing line. As each wafer passes adjacent the probe assembly, a source of modulated light, within the probe assembly, having a predetermined wavelength and frequency of modulation, impinges upon the wafer. A sensor in the probe assembly measures the surface photovoltage induced by the modulated light. A computer then uses the induced surface photovoltage to determine various electrical characteristics of the wafer.
1. A method of characterizing a substrate comprising the steps of:
providing a substrate, said substrate having a first surface photovoltage on the surface of a substrate;
conveying the substrate from a position not under a probe head to a position under the probe head during processing;
applying a light to the substrate to produce a second surface photovoltage on the surface of the substrate; and
measuring the first and second surface photovoltages by using the probe head; and
determining an electrical characteristic according to the difference of the first and second surface photovoltages.
2. The method according to claim 1 , wherein the substrate comprises a semiconductor substrate.
3. The method according to claim 2 , wherein the semiconductor substrate comprises a silicon substrate.
4. The method according to claim 1 , wherein the energy of the light is greater than an energy gap of the substrate.
5. The method according to claim 1 , wherein the probe head at least comprises a voltage sensor.
6. The method according to claim 5 , wherein the voltage sensor at least comprises an electrode.
7. The method according to claim 6 , wherein the electrode is made of indium-tin oxide.
8. The method according to claim 1 , wherein the light is semiconductor light-emitting diodes.
9. An apparatus for characterizing substrate, comprising:
a conveyer for conveying a substrate from a position not under a probe head to a position under the probe head during processing, said substrate having a first surface photovoltage on the surface of the substrate;
a light source for applying light to a substrate to produce a second surface photovoltage on the surface of the substrate;
a detector for measuring the first and second surface photovoltages by using the probe head; and
a processor in electrical communication with said detector for determining an electrical characteristic according to the difference of the first and second surface photovoltages.
10. The apparatus according to claim 9 , wherein the substrate comprises a semiconductor substrate.
11. The apparatus according to claim 10 , wherein the semiconductor substrate comprises a silicon substrate.
12. The apparatus according to claim 9 , wherein the energy of the light is greater than an energy gap of the substrate.
13. The apparatus according to claim 9 , wherein the probe head at least comprises a voltage sensor.
14. The apparatus according to claim 13 , wherein the voltage sensor at least comprises an electrode.
15. The apparatus according to claim 14 , wherein the electrode is made of indium-tin oxide.