GROWTH AND CHARACTERIZATION OF SILICON THIN-FILMS EMPLOYING SUPERSONIC JETS

Supersonic jets of Si2H6 have been employed to grow single crystalline silicon thin films on Si(100) and polysilicon surfaces at substrate t emperatures of 500-650 degrees C. Films deposited on Si(100) employing high and low kinetic energy jets are epitaxial as determined by refle ction high energy electron diffraction. The uniformity and growth of f ilms deposited on polysilicon by high energy similar to 2 eV (1% Si2H6 in hydrogen) and low energy similar to 0.09 eV (pure Si2H6) Si2H6 jet s are compared to silicon growth employing ultrahigh vacuum chemical v apor deposition (UHV-CVD). To ascertain the influence of high kinetic energy on the growth of silicon from disilane, the reaction probabilit y is estimated from growth measurements for all techniques and compare d. The high energy jet is found to have a substantially higher reactio n probability compared to the low energy jet and UHV-CVD indicating th at the growth is enhanced by the high energy disilane. The disilane fl ux distribution employing the high energy jet is sharply peaked along the centerline causing a peaked growth profile across the 4 in. wafer. The silicon growth profile obtained from the high energy jet broadens slightly as the substrate temperature decreases. The higher flux at t he centerline results in a higher hydrogen coverage compared to the wa fer edge which affects the reaction probability in the two locations r elative to one another. As the substrate temperature decreases, the gr owth profile flattens since the lower hydrogen desorption rate, and re sulting higher hydrogen coverage, reduces the disilane adsorption prob ability at the centerline more than at the wafer edge. The growth dist ribution from the high energy jet is found to become slightly less pea ked when the carrier gas is changed from hydrogen to helium. (C) 1997 American Vacuum Society.