Semiconductor device and method of manufacturing the same

Abstract

In a semiconductor device formed on a silicon surface which has a substantial (110) crystal plane orientation, the silicon surface is flattened so that an arithmetical mean deviation of surface Ra is not greater than 0.15 nm, preferably, 0.09 nm, which enables to manufacture an n-MOS transistor of a high mobility. Such a flattened silicon surface is obtained by repeating a deposition process of a self-sacrifice oxide film in an oxygen radical atmosphere and a removing process of the self-sacrifice oxide film, by cleaning the silicon surface in deaerated H 2 O or a low OH density atmosphere, or by strongly terminating the silicon surface by hydrogen or heavy hydrogen. The deposition process of the self-sacrifice oxide film may be carried out by isotropic oxidation.

1 . A method of manufacturing a semiconductor device, comprising the steps of:
 preparing a silicon semiconductor surface which has a predetermined crystal plane orientation;   isotropically oxidizing the silicon surface to form a self-sacrifice oxide film on the silicon surface to flatten the silicon surface into the prescribed arithmetical mean deviation of surface Ra;   removing the self-sacrifice oxide film to expose the flattened silicon surface;   cleaning the flattened silicon surface into a cleaned surface; and   forming a gate insulation film on the cleaned surface;   wherein:
 the isotropically oxidizing step comprises the step of:
 carrying out radical oxidation of the silicon surface within a radical oxidation atmosphere to form the self-sacrifice oxide film, and 
 
   wherein:
 the step of forming the gate insulation film is performed within an oxygen radical atmosphere by using gas plasma generated in a mixed gas of a rare gas selected from at least one of argon, krypton and xenon and an oxygen gas by microwave excitation. 
   
     
     
         2 . A method as claimed in  claim 1 , wherein the silicon surface is either a (100) crystal plane orientation or a (110) crystal plane orientation. 
     
     
         3 . A method as claimed in  claim 1 , wherein the silicon surface is flattened to surface roughness (Ra) of 0.08 nm or less after the self-sacrifice oxide film is formed within the radical oxidation atmosphere. 
     
     
         4 . A method as claimed in  claim 1 , wherein the self-sacrifice film is removed by the use of a mixed solution of HF and HCl mixed at the volume ratio of 1:19. 
     
     
         5 . A method as claimed in  claim 1 , wherein the gate insulation film includes at least one material selected from a group consisting of metal silicate, metal oxide, and metal nitride. 
     
     
         6 . A method as claimed in  claim 5 , wherein the metal oxide consists of at least one selected from a group consisting of oxides of Si, Hf, Zr, Ta, Ti, Y, Nb, Na, Co, Al, Zn, Pb, Mg, Bi, La, Ce, Pr, Sm, Eu, Gd, Dy, Er, Sr, and Ba.