Abstract A new technique for the controlled incorporation of doping impurities into homoepitaxial silicon films by gas bombardment with arsine and diborane has been investigated. Hall effect and conductivity measurements have been used to show that P and N-type silicon thin films, having mobility values close to those of bulk material may be evaporated at 700 DEG C onto silicon <111> substrates. The substrates are precleaned by evaporating 50A of silicon at 775 DEG C. Step etch measurements have shown that the gas doped films possess uniform impurity concentrations. Diode structures formed by evaporating P and N-type layers onto substrates of the opposite doping type have been investigated. These diodes show good rectification properties. Capacitance-voltage measurements confirm the abrupt nature of the evaporated junctions. Minority carrier lifetimes of 2 to 3 mu sec. have been measured in the evaporated structures.
A method of forming a semi-conductor junction comprising the steps of: i. cleaning a polished silicon substrate, ii. cleaning a silicon evaporation charge, iii. disposing said substrate and said charge in a high vacuum of 10 - 5 to 10 - 9 mm Hg, iv. heating said substrate to a deposition temperature in the range of 550° to 850°C., v. evaporating said charge onto the surface of said substrate at rates of 3 to 10 angstroms per second to deposit a film thereon, and vi. directing a decomposable doping gas into said high vacuum onto the substrate surface during the evaporation of said charge thereby causing a partial pressure rise in the overall vacuum, a chemical reaction occurring in which the doping gas decomposes releasing the dopant which is incorporated into said film.
Claim 2
Independent Claim
133 words
A method of forming a semi-conductor junction comprising the steps of: i. cleaning a polished silicon substrate, ii. cleaning a silicon evaporation charge, iii. disposing said substrate and said charge in a high vacuum of 10 - 5 to 10 - 9 mm Hg, iv. heating said substrate to a deposition temperature in the range of 550° to 850°C., v. evaporating said charge onto the surface of said substrate at rates of 3 to 10 angstroms per second to deposit a film thereon, and vi. directing a decomposable doping gas into said high vacuum onto the substrate surface during the evaporation of said charge thereby causing a partial pressure rise in the overall vacuum, a chemical reaction occurring in which the doping gas decomposes releasing the dopant which is incorporated into said film.
Claim 3
Dependent Claim
16 words
The method of claim 1 wherein said doping gas is selected from Arsine, Diborane, and Phosphine.
Claim 4
Dependent Claim
19 words
The method of claim 1 wherein said evaporation charge consists of near intrinsic silicon having a low oxygen content.
Claim 5
Dependent Claim
46 words
The method of claim 1 wherein said step (ii) is effected by exposing said substrate to evaporated silicon at a substrate temperature sufficient to permit etching of any oxide layer on the substrate for the purpose of providing a cleaner surface for growth to be effected.