Device for plasma treatment of electronic materials

Abstract

Plasma applications are disclosed that operate with argon and other molecular gases at atmospheric pressure, and at low temperatures, and with high concentrations of reactive species. The plasma apparatus and the enclosure that contains the plasma apparatus and the substrate are substantially free of particles, so that the substrate does not become contaminated with particles during processing. The plasma is developed through capacitive discharge without streamers or micro-arcs. The techniques can be employed to remove organic materials from a substrate, thereby cleaning the substrate; to activate the surfaces of materials, thereby enhancing bonding between the material and a second material; to etch thin films of materials from a substrate; and to deposit thin films and coatings onto a substrate; all of which processes are carried out without contaminating the surface of the substrate with substantial numbers of particles.

What is claimed is: 
     
         1 . An apparatus for producing an ionized gas plasma, comprising:
 a housing having an inlet for gas flow comprising argon and one or more molecular gases, an outlet for argon plasma comprising reactive neutral species, and a flow path within the housing for directing the gas flow;   a power electrode disposed within the housing having a powered electrode surface exposed to the gas flow;   a ground electrode disposed adjacent to the power electrode such that a grounded electrode surface is closely spaced from the power electrode surface and the gas flow is directed therebetween;   a power supply for delivering radio frequency power coupled to the power electrode and the ground electrode to ionize the gas flow and produce the argon plasma comprising the reactive neutral species;   an enclosure having the housing contained within and including an enclosure gas flow wherein the enclosure gas flow has been filtered to remove particles from the flow; and   a material substrate disposed within the enclosure near the outlet of the housing to receive the reactive neutral species in the gas flow from the ionized gas plasma.   
     
     
         2 . The apparatus of  claim 1 , wherein the argon plasma is produced by a capacitive discharge without substantially any streamers or micro-arcs. 
     
     
         3 . The apparatus of  claim 1 , wherein the reactive neutral species from the ionized gas plasma are used for cleaning organic contamination from the material substrate, activating the material substrate surface for adhesion, etching a thin film off of the material substrate, or depositing a thin film onto the material substrate, all substantially without the deposition of particles. 
     
     
         4 . The apparatus of  claim 1 , wherein the gas inside the enclosure is at atmospheric pressure. 
     
     
         5 . The apparatus of  claim 1 , wherein the gas flow through the housing is laminar. 
     
     
         6 . The apparatus of  claim 1 , wherein the gas flow from the outlet of the housing for the argon plasma is between 25 and 200° C. 
     
     
         7 . The apparatus of  claim 1 , wherein the outlet of the housing for argon plasma comprises a linear opening. 
     
     
         8 . The apparatus of  claim 7 , wherein the linear opening is at least as wide as the material substrate and the material substrate is passed at a constant speed relative to and contacting the reactive gas beam. 
     
     
         9 . The apparatus of  claim 1 , further comprising a means of translating the housing with the outlet for the ionized gas plasma relative to the surface of the material substrate such that the entire surface of the material substrate is uniformly treated with the reactive species from the ionized gas plasma. 
     
     
         10 . The apparatus of  claim 1 , wherein the power supply operates at a radio frequency of 13.56 or 27.12 MHz and includes an auto-tuning network that impedance matches the radio frequency power supply to the argon plasma to minimize reflected power. 
     
     
         11 . The apparatus of  claim 1 , wherein the one or more molecular gases are added to the argon gas flow at a concentration between 0.5 to 5.0 volume % and a fraction of the one or more molecular gases dissociates into atoms inside the argon plasma, and then flows out of the outlet, wherein the atoms are selected from the group consisting of O, N, H, F, C and S atoms. 
     
     
         12 . The apparatus of  claim 1 , wherein the enclosure gas flow is laminar. 
     
     
         13 . The apparatus of  claim 1 , wherein the enclosure includes no more than 100,000 particles larger than 0.1 micron per cubic meter of air. 
     
     
         14 . The apparatus of  claim 13 , wherein the enclosure comprises a cleanroom.