Substrate plasma processing apparatus and plasma processing method
A substrate plasma processing apparatus includes a substrate holding electrode and a counter electrode which are arranged in a chamber, a high frequency generating device which applies a high frequency of 50 MHZ or higher to the substrate holding electrode, a DC negative pulse generating device which applies a DC negative pulse voltage in a manner of superimposing on the high frequency, and a controller controlling to cause intermittent application of the high frequency and cause intermittent application of the DC negative pulse voltage according to the timing of on or off of the high frequency.
1. A substrate plasma processing apparatus, comprising:
a chamber capable of maintaining a vacuum therein;
a first electrode to hold a substrate in the chamber, the substrate being processed on a main surface thereof;
a counter electrode arranged to face the first electrode in the chamber;
a first supply unit configured to apply a high frequency power having a predetermined frequency of 50 MHz or higher to the first electrode;
a second supply unit configured to apply a predetermined DC negative pulse voltage in a manner of superimposing on the high frequency power to the first electrode;
a control unit configured to periodically turn on and off both of the first and second supply units so as to repeat in sequence a first period, a second period, and a third period, in the first period both of the high frequency power and the DC negative pulse voltage being applied to the first electrode, in the second period only the high frequency power being applied to the first electrode, and in the third period none of the high frequency power and the DC negative pulse voltage being applied to the first electrode.
2. The apparatus according to claim 1 ,
wherein when plasma processing an insulating film or a film having an insulator on a bottom portion, the period is a preset charge-up alleviation time T pre ,
where T pre ≧Q max /(ZeBN i v b ), Q max is a maximum charge amount per unit area that does not cause damage, Z is ionic valency, v b is Bohm speed as v b =(kT e /M i ) 1/2 , T e is electron temperature, k is Boltzmann's constant, M i is ion mass, B is plasma density ratio of a sheath end portion and a bulk portion, e is elementary electric charge, and N i is ion density.
3. The apparatus according to claim 2 ,
wherein the period is equal to or larger than 5.18 microseconds.
4. The apparatus according to claim 1 ,
wherein the control unit periodically turns on the second supply unit so as to repeat in sequence the fist period, the second period, the third period, and a fourth period, in the fourth period only the high frequency power being applied to the first electrode.
5. The apparatus according to claim 4 ,
wherein the second period is equal to or larger than 4 microseconds.