Abstract: A sample table for holding a silicon substrate into which an impurity is introduced is provided in the lower portion of a vacuum chamber. A high frequency power source is connected to the sample table through a coupling capacitor. The high frequency power source has a self-bias of 500 V, for example. Gas introducing means for introducing a sputtering gas such as an argon gas is provided on the bottom of the vacuum chamber. A solid target which contains an impurity which should be introduced, for example, boron is provided in the upper portion of the vacuum chamber.