US 9,812,371 B2
Methods for reducing metal contamination on a surface of a sapphire substrate by plasma treatment
Thierry Barge, Chevrieres (FR)
Assigned to Soitec, Bernin (FR)
Filed by Soitec, Bernin (FR)
Filed on Mar. 23, 2016, as Appl. No. 15/78,902.
Claims priority of application No. 15 52416 (FR), filed on Mar. 24, 2015.
Prior Publication US 2016/0284608 A1, Sep. 29, 2016
Int. Cl. H01L 21/20 (2006.01); H01L 21/263 (2006.01); H01L 21/86 (2006.01); H01L 21/762 (2006.01); H01L 29/06 (2006.01); H01L 21/02 (2006.01)
CPC H01L 21/86 (2013.01) [H01L 21/02046 (2013.01); H01L 21/2011 (2013.01); H01L 21/263 (2013.01); H01L 21/76251 (2013.01); H01L 29/0649 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method for reducing metal contamination on a surface of a sapphire substrate comprising a plasma treatment of the sapphire surface by ion bombardment, wherein a plasma of a supplied gas is generated and wherein a bombardment energy of ions in the plasma is controlled by a radio frequency electromagnetic field providing a power density between 2.0 watts/cm2 and 3.0 watts/cm2, the bombardment energy of the ions being higher than a first threshold sufficient to tear the metal contamination from the sapphire surface, and the bombardment energy of the ions being lower than a second threshold so as to prevent a surface quality degradation of the sapphire surface.
 
11. A method for reducing metal contamination on a surface of a sapphire substrate comprising a plasma treatment of the sapphire surface by ion bombardment, wherein a plasma of a supplied gas is generated and wherein a bombardment energy of ions in the plasma is controlled by a radio frequency electromagnetic field providing a power density between 2.0 watts/cm2 and 4.0 watts/cm2, the bombardment energy of the ions being higher than a first threshold sufficient to tear the metal contamination from the sapphire surface, and the bombardment energy of the ions being lower than a second threshold so as to prevent a surface quality degradation of the sapphire surface, wherein a surface roughness of the sapphire surface remains below a root-mean-square (RMS) value of 0.5 nm.