Method for growing single crystalline silicon with intermediate bonding agent and combined thermal and photolytic activation

A method for epitaxially growing single crystalline silicon on a silicon substrate from a semiconductor-bearing gas at a temperature below the pyrolytic threshold of said siliconbearing gas, comprising:

• providing a silicon substrate exposed to ambient to have an oxide layer thereon;
• exposing said substrate to a first atmosphere having a first bonding agent with a stronger bonding affinity to silicon than the bonding affinity of oxygen to silicon, to replace the silicon-oxide bonds;
• exposing said substrate to a second atmosphere having a second bonding agent with a bonding affinity to silicon;
• applying laser radiation against said substrate in the presence of said second atmosphere to break the bond between the silicon and the first bonding agent and replace it with a bond between the silicon and the second bonding agent;
• without exposing said substrate to ambient, exposing said substrate to a third atmosphere having a silicon-bearing gas;
• heating said substrate in the presence of said third atmosphere to a temperature below the pyrolytic threshold of said silicon-bearing gas;
• applying laser radiation against said substrate while heated and in the presence of said third atmosphere to break the bond between the silicon and the second bonding agent and to break the bonds in the silicon-bearing gas to decompose the latter to atomic silicon which bonds with the new unbonded silicon atoms in said substrate to epitaxially grow single crystalline silicon thereon;
• exposing said substrate to ambient after said step of exposing said substrate to said first atmosphere such that another oxide layer forms on said substrate, and removing said other oxide layer during said step of applying laser radiation against said substrate in the presence of said second atmosphere.

A method of epitaxially growing single crystalline silicon on a silicon substrate from a silicon-bearing gas at a temperature below the pyrolytic threshold of said silicon-bearing gas, comprising:

• providing a silicon substrate exposed to ambient to have an oxide layer thereon;
• fluorinating said substrate to replace silicon-oxide bonds with silicon-fluorine bonds and provide an adsorbed fluorinated layer;
• exposing said substrate to a hydrogen atmosphere and applying laser radiation against said substrate to break said silicon-fluorine bonds and remove the fluorinated layer and replace them with silicon-hydrogen bonds;
• without exposing said substrate to ambient, exposing said substrate to a silicon-bearing gas and heating said substrate to a given temperature below the pyrolytic threshold of said silicon-bearing gas and applying laser radiation against said substrate to break said silicon-hydrogen bonds and replace them with silicon-silicon bonds to epitaxially grow single crystalline silicon on said substrate;
• after said fluorination step, exposing said substrate to ambient to form another oxide layer thereon, and, during said step of exposing said substrate to said hydrogen atmosphere and applying laser radiation, removing said other oxide layer to substrate to ambient, continuing said process by exposing said substrate to said silicon-bearing gas.

A method for epitaxially growing single crystalline silicon on a silicon substrate from disilane Si.sub.2 H.sub.6 at a temperature below the pyrolytic threshold of disilane, comprising:

• providing a silicon substrate exposed to ambient to have an oxide layer thereon ##STR1## fluorinating said substrate in hydrogenfluoride to remove the oxide layer and substitute therefore fluorine atoms bonding with silicon atoms in the substrate and forming a fluorinated layer ##STR2## where y and z equal 1, 2, 3 or fractions thereof;
• exposing said substrate to ambient such that another oxide layer forms thereon ##STR3## applying laser radiation against said substrate in the presence of hydrogen gas such that photolytic excitation removes said other oxide layer and breaks the silicon-fluorine bond and removes the fluorinated layer, and hydrogen is substituted for the fluorine to provide a silicon-hydrogen bond and hydrogen-fluoride ##STR4## without exposing said substrate to ambient, heating said substrate and applying laser radiation against said substrate in the presence of disilane such that combined thermal and photolytic excitation breaks the silicon-hydrogen bonds and such that the disilane decomposes to silane and unstable SiH.sub.z which in turn decomposes to hydrogen and atomic silicon, which atomic silicon bonds with now unbonded silicon atoms in said substrate to epitaxially grow single crystalline silicon thereon ##STR5##