Cleaning device and cleaning process for a plasma reactor

Abstract

The invention concerns a device and a process, the device being a cleaning device utilizing a dry chemical means assisted by plasma from a reactor ( 10 ) containing an unwanted deposit on its walls and at least one other polarizable surface ( 12 ), characterized in that it comprises means ( 13, 14 ) for positively polarizing one or each of the polarizable surfaces relative to the reactor walls maintained at a reference potential.

1 . Method of cleaning, by plasma-assisted dry chemical method, a reactor ( 10 ) having an undesirable deposit on its walls and on at least one other biasable surface ( 12 ), characterised in that there are effected a plurality of alternating successions of:
 a so-called negative sequence ( 1 ) of cleaning the or each biasable surface by negative biasing thereof, with respect to the walls of the reactor; and   a so-called positive sequence ( 2 ) of cleaning the walls of the reactor by positive biasing of the or each biasable surface, with respect to the walls of the reactor, the walls being at a referenced potential.   
     
     
         2 . Method according to the preceding claim, characterised in that a plurality of periodic alternating successions of a negative sequence ( 1 ) and a positive sequence are implemented. 
     
     
         3 . Method according to one of the preceding claims, characterised in that a biasing to a referenced voltage of the or each biasable surface ( 12 ) is performed during the positive sequence ( 2 ). 
     
     
         4 . Method according to one of the preceding claims, characterised in that a biasing to a referenced voltage b of the or each biasable surface ( 12 ) during the negative sequence ( 1 ) is carried out. 
     
     
         5 . Method according to one of the preceding claims, characterised in that an auto-biasing of the or each biasable surface ( 12 ) is carried during the negative sequence ( 1 ). 
     
     
         6 . Device for cleaning, by plasma-assisted dry chemical method, a reactor ( 10 ) having an undesirable deposit on its walls and on at least one other biasable surface ( 12 ), characterised in that it comprises:
 means ( 13 ,  14 ,  140 ,  15 ,  16 ) for negatively biasing, with respect to the walls of the reactor, the or each biasable surface;   means ( 13 ,  14 ,  140 ,  15 ,  16 ) for positively biasing, with respect to the walls of the reactor maintained at a reference potential, the or each biasable surface;   means ( 14 ,  15 ,  140 ,  16 ) for successively alternating the sign of the biasing, with respect to the walls of the reactor, of the or each biasable surface.   
     
     
         7 . Device according to the preceding claim, characterised in that it comprises a DC voltage generator ( 14 ) electrically connected to the or each biasable surface, and means of controlling the generator in order to successively deliver positive and negative voltages, with reference to the walls of the reactor. 
     
     
         8 . Device according to one of  claim 6  or  7 , characterised in that it comprises means for successively and periodically alternating the sign of the biasing, with respect to the walls of the reactor, of the or each biasable surface. 
     
     
         9 . Device according to the preceding claim, characterised in that it comprises a periodic voltage generator ( 140 ), electrically connected to the or each biasable surface by means of a circuit ( 15 ) comprising a low-impedance capacitor ( 151 ) and means ( 152 ) for short-circuiting the capacitor. 
     
     
         10 . Device according to  claim 7 , characterised in that it comprises a periodic voltage generator ( 140 ) in direct electrical connection ( 13 ) with the or each biasable surface and referenced with respect to the walls of the reactor, which are preferably earthed. 
     
     
         11 . Device according to one of  claims 7  to  10 , characterised in that the biasable surface has a dimension such that it satisfies the inequality:
     S   s   /S   w >1.5( m   e   /m   i ) 1/2      
       so as to disturb the plasma, so that the potential of the plasma V p  is positioned, at each moment t, at a value more positive than the most positive surface of the reactor, and where S s  is the biasable surface, S w  the surface of the walls of the reactor, m e  the mass of the electrons of the plasma and m i  that of the ions of the plasma.