Plasma processing method and equipment used therefor

A plasma processing method for processing an object using plasma, said method comprising the steps of:

• placing an object on a holder provided in a plasma chamber;
• supplying a reaction gas to said chamber;
• supplying an alternating excitation signal for exciting said plasma to said reaction gas contained in said chamber said excitation signal being in the form of pulses, each of said pulses of said excitation signal having an on-period for supplying said excitation signal and an off-period for stopping said excitation signal, said off-period ranging from 10 .mu.sec to 100 .mu.sec;
• and
• applying an alternating bias signal to said object placed in said chamber, said bias signal having a frequency of at most 600 kHz;
• wherein negative ions and positive ions are temporarily generated in said plasma during said off-period;
• and wherein said generated negative ions and said positive ions follow the change of said applied, alternating bias signal, impinging on said object during every half cycle.

A plasma processing apparatus for processing an object using plasma, said apparatus comprising:

• a plasma chamber in which said plasma is generated;
• a plasma excitation signal source for supplying an excitation signal to said chamber, said alternating excitation signal being supplied in the form of pulses each of which has an on-period for supplying said excitation signal and an off-period for stopping said excitation signal;
• a gas source for supplying a reaction gas to said chamber;
• a gas removing system for removing said gas contained in said chamber;
• an object holder for holding said object thereon in said chamber;
• and
• a bias signal source for supplying an bias signal to said object placed on said holder;
• wherein said off-period of said excitation signal ranges from 10 .mu.sec to 100 .mu.sec, and said alternating bias signal has a frequency of at most 600 kHz.