| abstract |
A method and apparatus are provided for determining the doping concentration profile of a specimen of semiconductor material. The apparatus includes a sensor assembly (21) having a sensor tip (22) which is mounted on an air bearing assembly (47). The air bearing assembly (47) is suspended from a housing (43) by a pair of bellows (81, 83). In use, air is supplied to the air bearing assembly (47) through the bellows (81, 83) causing the bellows (81, 83) to expand, lowering the sensor tip (21) until the air bearing action stops the expansion. In other implementations of the invention, photocurrent or photovoltage are not used and the doping concentration profile is determined using the total capacitance, the capacitance of air, the DC bias voltage and the area of the electrode spaced from the specimen information. |