An improvement of the RI Auger electron thickness gauge for the measurement of thin metal films

The RI (Radio Isotope) Auger electron thickness gauge presented in a previous paper is improved so that the gauge can be applied to the measurement of thin metal films and also the ion charge-up effect on a non-conducting specimen film can be removed. A negative voltage of a few volts against the specimen film is supplied to the nickel grid which is attached on the counter side of the aperture of the diaphragm as the window of a GM counter. Secondary electrons produced by Auger electrons in Q gas (He 99%, isobutane 1%) between a specimen and the nickel grid are repulsed toward the specimen and are prevented from entering the GM counter. Also ions produced by the electron avalanche in the GM counter are prevented from charging up on the specimen. Aluminium films of mass per unit area 10μg/cm2 can be measured with a 6% error. (Auth.)