Electroless-plated deposit process for silicon based dielectric insulating material

Abstract

Process for thin-film electroless-plated deposition onto the substrate, which is either hydrophilic or hydrophobic silicon based dielectric material (e.g., silicon dioxide, silicate glass, or polysiloxanes), is a substitute for the conventional sensitization/activation route by pre-treating the surface of the dielectric substrate by plasma (H 2 /N 2 , N 2 , H 2 , or O 2 ), immersing the substrate in a basic aqueous solution for removing hydrogen, immersing the substrate in a basic aqueous solution of metal ions for adsorbing the metal ions thereon, reducing the metal ions on the surface of the substrate, and immersing the substrate in an electroless-plating solution to deposit an electroless-plated metal film. The substrate formed of hydrophobic polysiloxanes which is properly pretreated by gaseous plasma can be immersed in a basic solution with strong oxidizing capability and/or performing a selective pattern by plasma treatment. Thus the metal film self-aligned patterns can be achieved electrochemically by this process.

1 . A process for ultrathin electroless-plated metal film on a dielectric substrate formed of silicon based dielectric material being either hydrophilic or hydrophobic, comprising the steps of: 
 (i) treating the surface of the substrate by plasma;    (ii) immersing the substrate in a basic aqueous solution;    (iii) removing hydrogen from the surface of the substrate;    (iv) immersing the substrate in a basic aqueous solution having metal ions for adsorbing the metal ions onto the surface of the substrate;    (v) reducing the metal ions on the surface of the substrate; and    (vi) immersing the substrate in an electroless-plated solution for depositing an electroless-plated metal film.    
     
     
         2 . The process of  claim 1 , wherein the silicon based dielectric material is selected from silicon dioxide or silicate glass or polysiloxanes so as to form an active surface on the substrate and form a negatively charged surface on the substrate after performing the step (ii) for adsorbing the metal ions as catalytic seeding for electroless-plating deposition.  
     
     
         3 . The process of  claim 2 , wherein the silicon based dielectric material selected from either the hydrophilic silicon dioxide or the hydrophilic silicate glass is immersed in a basic aqueous solution for depositing the electroless-plated metal film irrespective of the plasma treatment.  
     
     
         4 . The process of  claim 2 , wherein the silicon based dielectric material selected from the hydrophobic polysiloxanes undergoes the step (i) to form a hydrophilic surface, plasma is formed of one of ionized gas including N 2 /H 2 , N 2 , H 2 , and O 2 , and the basic aqueous solution is a strong oxidizing agent for depositing the electroless-plated metal film.  
     
     
         5 . The process of  claim 4 , wherein the substrate formed of the hydrophobic polysiloxanes is immersed in a basic aqueous solution with strong oxidizing capability for developing a negatively charged surface and performing a selective treatment on the surface of the substrate by plasma to form a self-aligned electroless-plated metal film pattern with very small (<20 nm) thickness.