Method and apparatus for non-aggressive plasma-enhanced vapor deposition of dielectric films

Abstract

While performing plasma-enhanced chemical vapor deposition on a substrate by exposing the substrate in a vacuum to a flow of particles generated by a plasma, which particles react to form a passivation layer on the substrate, a grid is interposed between the plasma and the substrate, thereby reducing the flow of charged particles towards the substrate while conserving a flow of neutral particles. The grid is formed of metal wires that are crossed at a pitch that is less than two or three times the Debye length (λD) of the plasma used, at least at the beginning of deposition. The aging properties of semiconductor components made by such a method is thereby improved.

1 . Apparatus for depositing dielectric films on a substrate by a plasma-enhanced chemical vapor deposition method, the apparatus comprising: 
 a source of high-density ion plasma;    means for projecting plasma particles onto the substrate; and    a selective trap for at least substantially reducing the flow of charged particles towards the substrate while conserving a flow of neutral particles which react to form a passivation layer on the substrate;    said apparatus further comprising means for selectively retracting the trap, such that the trap is interposed in the flow of particles during an initial step of non-aggressive deposition, and the trap is retracted from the flow of particles during a following step of rapid deposition wherein deposition occurs more rapidly than during said non-aggressive deposition said.    
     
     
         2 . Apparatus according to  claim 1 , in which the selective trap comprises a metal grid interposed between the plasma and the substrate.  
     
     
         3 . Apparatus according to  claim 2 , in which the metal grid is formed by metal wires crossed at a pitch that is determined as a function of the characteristics of the plasma to block the flow of charged particles.  
     
     
         4 . Apparatus according to  claim 3 , in which the pitch of the grid is less than two to three times the Debye length λD of the plasma used, at least at the beginning of deposition.  
     
     
         5 . Apparatus for depositing dielectric films on a substrate by a plasma-enhanced chemical vapor deposition method, the apparatus comprising: 
 a source of high-density ion plasma;    means for projecting plasma particles onto the substrate; and    a selective trap for at least substantially reducing the flow of charged particles towards the substrate while conserving a flow of neutral particles which react to form a passivation layer on the substrate;    in which the selective trap comprises a metal grid interposed between the plasma and the substrate, the grid being formed by metal wires crossed at a pitch that is determined as a function of the characteristics of the plasma to block the flow of charged particles; and    in which the apparatus includes adaptation means for modifying the Debye length λD of the particles of the plasma, the grid remaining interposed permanently in the flow of particles during deposition, whereby the adaptation means provide a plasma having a Debye length λD that is greater than one-third or half the pitch of the grid during an initial step of non-aggressive deposition, and the adaptation means provide a plasma of Debye length λD that is considerably smaller than one-third or half the pitch of the grid during a following step of rapid deposition where deposition occurs more rapidly than during said non-aggressive deposition.    
     
     
         6 . Apparatus according to  claim 1 , including a clamping ring, in which the grid is insulated from the clamping ring and is biased to a potential different from the potential of the clamping ring.  
     
     
         7 . Apparatus according to  claim 5 , including a clamping ring, in which the grid is insulated from the clamping ring and is biased to a potential different from the potential of the clamping ring.  
     
     
         8 . The use of apparatus according to  claim 1  for passivating a semiconductor substrate based on silicon, germanium, indium phosphide, gallium arsenide, or an II-VI compound, by means of a passivation layer of the dielectric film type.  
     
     
         9 . The use of apparatus according to  claim 5  for passivating a semiconductor substrate based on silicon, germanium, indium phosphide, gallium arsenide, or an II-VI compound, by means of a passivation layer of the dielectric film type.  
     
     
         10 . Apparatus according to  claim 5 , including a clamping ring, in which the grid is insulated from the clamping ring and is biased to a potential different from the potential of the clamping ring.  
     
     
         11 . The use of apparatus according to  claim 5  for passivating a semiconductor substrate based on silicon, germanium, indium phosphide, gallium arsenide, or an II-VI compound, by means of a passivation layer of the dielectric film type.