Plasma treatment system and cleaning method of the same
A plasma treatment apparatus has a reaction vessel ( 11 ) provided with a top electrode ( 13 ) and a bottom electrode ( 14 ), and the first electrode is supplied with a VHF band high frequency power from a VHF band high frequency power source ( 32 ), while the bottom electrode on which a substrate ( 12 ) is loaded and is moved by a vertical movement mechanism. The plasma treatment system has a controller ( 36 ) which, at the time of a cleaning process after forming a film on the substrate ( 12 ), controls a vertical movement mechanism to move the bottom electrode to narrow the gap between the top electrode and bottom electrode and form a narrow space and starts cleaning by a predetermined high density plasma in that narrow space. In the cleaning process, step cleaning is performed. Due to this, the efficiency of utilization of the cleaning gas is increased, the amount of exhaust gas is cut, and the cleaning speed is raised. Further, the amount of the process gas used is cut and the process cost is reduced.
1. A cleaning method of a plasma treatment system, for growing an insulating film on a substrate by plasma CVD, then taking out the substrate, and then removing the film deposited inside a chamber by plasma, wherein the plasma treatment system is constructed to cover an inside wall of the chamber down to at least 3 cm from a main surface of a first electrode by an insulator ring, the cleaning method comprising sequential steps of:
forming a gap between the first electrode and a second electrode of at least 0.5 cm and a gap of not more than 5 mm between the insulator ring and the second electrode, and performing a first cleaning by generating a first density plasma,
lowering the second electrode to a bottom surface of the insulator ring, and performing a second cleaning by generating the first density plasma, and
lowering the second electrode to its lowest position lower than the bottom surface of the insulator ring, and performing a third cleaning by generating a second density plasma having a density lower than the first density plasma,
the first density plasma and second density plasma being generated by power of a very high frequency.
2. A cleaning method of a plasma treatment system as set forth in claim 1 , wherein the gap formed between the first electrode and the second electrode is 1 to 2 cm.
3. A cleaning method of a plasma treatment system as set forth in claim 1 , wherein the density of the first density plasma is substantially 5×10 11 cm −3 and the density of the second density plasma is substantially 1×10 10 cm −3 .
4. A cleaning method of a plasma treatment system as set forth in claim 1 , wherein the first density plasma of the first cleaning is generated by superposing a power of a low frequency or medium frequency on the supplied very high frequency power.
5. A cleaning method of a plasma treatment system as set forth in claim 1 , wherein the first density plasma of the first cleaning and second cleaning is generated by superposing a power of a low frequency or medium frequency on the supplied very high frequency power.