In-situ determn. of thin electrically conductive films resistance - includes elimination of distorting plasma effects

摘要

Two voltage or current sources are used to produce a current in a circuit consisting of two current branches bracketing a film whose resistance is to be determd. in situ as a part of process control. The noise current I induced by plasma in the film is fed in equal parts into the two current branches which have equal resistances. The resultant currents I and I are measured directly or as voltage drops over known resistances. The average in these values is used to determine the measuring current I - which is independent of the plasma effect - and hence the true film resistance. The voltage or current sources pref. generate a direct current or an alternating current with a definite frequency. There are two symmetric current branches each with its own voltage source and measurement resistor. These resistors are chosen so that they and the film are subjected to about the same voltage. The measurement resistors are adjusted, in partic., stepwise to the varying resistance of the film in the course of its mfr. Four-point measurement in accordance with the Van der Pouw method is used to obtain measurement signals. The two current branches without voltage or current sources are short-circuited to determine the ion flow or the internal resistance of plasma. USE/ADVANTAGE - The invention can be used in the semiconductor circuit industry. In contrast to known methods, it allows the distortion of the measurement results by plasma effects to be completely eliminated and the film resistance to be determd. with a high deg. of accuracy.