Methods of forming a doped semiconductor thin film, doped semiconductor thin film structures, doped silane compositions, and methods of making such compositions
View Patent ↗Methods for forming doped silane and/or semiconductor thin films, doped liquid phase silane compositions useful in such methods, and doped semiconductor thin films and structures. The composition is generally liquid at ambient temperatures and includes a Group IVA atom source and a dopant source. By irradiating a doped liquid silane during at least part of its deposition, a thin, substantially uniform doped oligomerized/polymerized silane film may be formed on a substrate. Such irradiation is believed to convert the doped silane film into a relatively high-molecular weight species with relatively high viscosity and relatively low volatility, typically by cross-linking, isomerization, oligomerization and/or polymerization. A film formed by the irradiation of doped liquid silanes can later be converted (generally by heating and annealing/recrystallization) into a doped, hydrogenated, amorphous silicon film or a doped, at least partially polycrystalline silicon film suitable for electronic devices. Thus, the present invention enables use of high throughput, low cost equipment and techniques for making doped semiconductor films of commercial quality and quantity from doped “liquid silicon.”
1. A composition, comprising:
a) a compound of the formula A x H y , where each A is independently Si or Ge, x is from 3 to 20, and y is from x to (2x+2); and
b) at least one dopant of the formula B a R 1 b and/or (R 2 3 A) r A c (BR 1 2 ) s , where a is 1 or 2; b is 3a; each R 1 is independently H, C 2 -C 6 alkyl, aralkyl, aryl, or AR 2 3 , at least a of the b and each of the 2s instances of R 1 is hydrocarbyl having at least 3 carbon atoms, and when at least one of the b instances of R 1 in the formula B a R 1 b is t-butyl or phenyl, at least 1 of the remaining instances of R 1 in the formula B a R 1 b is H, aralkyl, or AR 2 3 ; R 2 is hydrogen, aryl, or A z H 2z+1 ; z is 1 to 4; c is 1 to 4, r+s=2c+2, and s≧1.
2. The composition of claim 1 , wherein said compound has the formula (AH x ) k , where k is from 3 to 12, and each of the k instances of x is 1 or 2.
3. The composition of claim 2 , wherein said compound is monocyclic, k is from 4 to 8, and x is 2.
4. The composition of claim 1 , wherein A is Si.
5. The composition of claim 4 , wherein said dopant has the formula B a R 1 b , where at least a instances of R 1 are C 3 -C 6 alkyl or C 6 -C 10 aryl, and the remainder of the b instances of R 1 are independently H, C 2 -C 6 alkyl, C 6 -C 10 aryl, C 7 -C 10 aralkyl or AR 2 3 , where R 2 is hydrogen or A z H 2z+1 (1≦z≦4).
6. The composition of claim 5 , wherein all of the instances of R 1 are C 3 -C 6 alkyl.
7. The composition of claim 6 , wherein all of the instances of R 1 are propyl and/or butyl.
8. The composition of claim 1 , wherein the at least one dopant has the formula B a R 1 b , at least a instances of R 1 are C 3 -C 6 alkyl or C 6 -C 10 aryl, and the remainder of the b instances of R 1 are H, C 2 -C 6 alkyl, C 6 -C 10 aryl, or AR 2 3 , where R 2 is hydrogen or A z H 2z+1 (1≦z≦4).
9. The composition of claim 8 , wherein the at least one dopant has the formula BR 1 3 , at least one instance of R 1 is C 3 -C 6 alkyl, and the remainder of the instances of R 1 are C 3 -C 6 alkyl, phenyl, or AH 3 .
10. The composition of claim 1 , wherein from 0.00001 to 50 vol % of said composition consists essentially of said dopant and from 0.5 to 99.999 vol % of said composition consists essentially of said compound.
11. The composition of claim 10 , further comprising a solvent in which said compound and said dopant are soluble.
12. The composition of claim 11 , wherein said solvent is selected from the group consisting of alkanes, substituted alkanes, cycloalkanes, substituted cycloalkanes, arenes, substituted arenes, and (cyclic) siloxanes.
13. The composition of claim 12 , wherein said solvent is selected from the group consisting of C 5 -C 10 monocycloalkanes; C 3 -C 8 monocycloalkanes substituted with from 1 to 2n C 1 -C 4 alkyl or halogen substituents or from 1 to n C 1 -C 4 alkoxy substituents; C 10 -C 14 polycycloalkanes; siloxanes of the formula (R 3 3 Si)(OSiR 3 2 ) p (OSiR 3 3 ), where p is from 0 to 4, and each R 3 is independently H, C 1 -C 6 alkyl, benzyl or phenyl substituted with from 0 to 3 C 1 -C 4 alkyl groups; cyclosiloxanes of the formula (SiR 4 2 O) q , where q is from 2 to 6, and each R 4 is independently H, C 1 -C 6 alkyl, benzyl or phenyl substituted with from 0 to 3 C 1 -C 4 alkyl groups; and C 3 -C 8 fluoroalkanes substituted with from 1 to (2n+2) fluorine atoms, where n is the number of carbon atoms in the selected solvent.
14. The composition of claim 13 , wherein said solvent is a C 6 -C 10 monocycloalkane or a C 10 -C 14 polycycloalkane.
15. The composition of claim 13 , wherein A is Si.
16. The composition of claim 11 , wherein from 0.5 to 50 vol % of said composition consists essentially of said compound.
17. The composition of claim 16 , wherein from 1 to 35 vol % of said composition consists essentially of said compound.
18. The composition of claim 17 , wherein from about 5 to 25 vol % of said composition consists essentially of said compound.
19. The composition of claim 11 , wherein from about 1 to about 25 wt. % of said composition consists essentially of said compound, and dopant is present in an amount providing from about 0.0001 to about 10 at. % of B atoms with respect to A atoms in said compound.
20. The composition of claim 1 , wherein said dopant has the formula BR 1 3 and/or (R 2 3 A) r A(BR 1 2 ) s , where R 1 is C 3 -C 6 alkyl, R 2 is hydrogen, r+s=4, and s≧3.
21. The composition of claim 1 , wherein aralkyl is C 7 -C 10 aralkyl, and aryl is C 6 -C 10 aryl.