Deposition of silicon nitride with enhanced selectivity
The use of selective deposition of silicon nitride can eliminate conventional patterning steps by allowing silicon nitride to be deposited only in selected and desired areas. Using a silicon iodide precursor alternately with a thermal nitrogen source in an ALD or pulsed CVD mode, silicon nitride can be deposited preferentially on a surface such as silicon nitride, silicon dioxide, germanium oxide, SiCO, SiOF, silicon carbide, silicon oxynitride, and low k substrates, while exhibiting very little deposition on exposed surfaces such as titanium nitride, tantalum nitride, aluminum nitride, hafnium oxide, zirconium oxide, aluminum oxide, titanium oxide, tantalum oxide, niobium oxide, lanthanum oxide, yttrium oxide, magnesium oxide, calcium oxide, and strontium oxide.
1 . A process for depositing a silicon nitride film on a microelectronic device substrate having a plurality of surfaces of differing composition, which comprises
a. contacting the substrate with pulsed silicon tetraiodide or disilicon hexaiodide, and nitrogen-containing co-reactants, at a temperature of about 150° C. to about 400° C., at a pressure below about 15 Torr, under vapor deposition conditions, thereby defining a pulse cycle, and
b. wherein the substrate is (i) pre-treated with ammonia plasma, and wherein (ii) the substrate is further treated with ammonia plasma periodically between sets of pulse cycles.
2 . The process of claim 1 , wherein the substrate is further treated at least one time with ammonia plasma in the range of after every 10 to after every 1000 pulse cycles.
3 . The process of claim 1 , wherein the substrate is further treated with ammonia plasma after every 15 pulse cycles.
4 . The process of claim 1 , wherein the substrate is further treated with ammonia plasma after every 20 pulse cycles.
5 . The process of claim 1 , wherein the substrate is further treated with ammonia plasma after every 25 pulse cycles.
6 . The process of claim 1 , wherein the substrate is further treated with ammonia plasma after every 30 pulse cycles.
7 . The process of claim 1 , wherein the substrate is further treated with ammonia plasma after every 35 pulse cycles.
8 . The process of claim 1 , wherein the substrate is further treated with ammonia plasma after every 40 pulse cycles.
9 . The process of claim 1 , wherein the substrate is further treated with ammonia plasma after every 45 pulse cycles.
10 . The process of claim 1 , wherein the substrate is further treated at least one time with ammonia plasma in the range of after every 50 to every 200 pulse cycles.
11 . The process of claim 1 , wherein silicon nitride is deposited onto surfaces chosen from silicon nitride, silicon dioxide, germanium oxide, SiCO, SiC, SiON, SiOF, and low-k substrates.
12 . The process of claim 1 , wherein the silicon nitride film is deposited onto surfaces chosen silicon nitride, silicon dioxide, germanium oxide, SiCO, SiC, SiON, SiOF, and low-k substrates over deposition onto surfaces chosen from titanium nitride, tantalum nitride, aluminum nitride, hafnium oxide, zirconium oxide, aluminum oxide, titanium oxide, tantalum oxide, niobium oxide, lanthanum oxide, yttrium oxide, magnesium oxide, calcium oxide, strontium oxide, and combinations thereof, at a selectivity of greater than about 85%.
13 . The process of claim 1 , wherein the device substrate comprises at least one surface comprised of silicon dioxide and at least one surface comprising aluminum oxide, and wherein the process results in preferential deposition of silicon nitride on the silicon dioxide at a selectivity of about 99% in a silicon nitride film deposited on the silicon dioxide surface and wherein the silicon nitride film has a thickness of at least about 200 Å.
14 . The process of claim 1 , wherein the device substrate comprises at least one surface comprised of silicon dioxide and at least one surface comprising aluminum oxide, and wherein the process results in preferential deposition of silicon nitride on the silicon dioxide at a selectivity of about 99% in a silicon nitride film deposited on the silicon dioxide surface and wherein the silicon nitride film has a thickness of at least about 50 Å.
15 . The process of claim 1 , wherein the process comprises at least three ammonia plasma treatments.
16 . The process of claim 1 , wherein the process produces silicon nitride films with improved refractive index compared to processes with the same precursor and deposition conditions which lack the periodic ammonia plasma treatments.
17 . A microelectronic device having a plurality of surfaces of differing composition, wherein the device comprises at least one first surface comprising at least one surface chosen from silicon nitride, silicon dioxide, germanium oxide, SiCO, SiC, SiON, SiOF, and low-k substrates, and one surface comprising at least one second surface chosen from titanium nitride, tantalum nitride, aluminum nitride, hafnium oxide, zirconium oxide, aluminum oxide, titanium oxide, tantalum oxide, niobium oxide, lanthanum oxide, yttrium oxide, magnesium oxide, calcium oxide, strontium oxide, and wherein the first surface has deposited thereon a silicon nitride film having a thickness of at least 200 Å, and wherein the second surface has deposited thereon a silicon nitride film having a thickness of no more than about 3 Å.
18 . A microelectronic device having a plurality of surfaces of differing composition, wherein the device comprises at least one surface comprising silicon dioxide, and at least one surface comprising aluminum oxide, and wherein the surface comprising silicon dioxide has deposited thereon a silicon nitride film having a thickness of at least 200 Å, and wherein the surface comprising aluminum oxide has deposited thereon a silicon nitride film having a thickness of no more than about 3 Å.
19 . A process for selectively depositing a silicon nitride film on a microelectronic device substrate having a plurality of surfaces of differing composition, which comprises:
treating the device with an ammonia plasma;
repeatedly contacting the device with pulsed silicon tetraiodide or disilicon hexaiodide, and nitrogen-containing co-reactants, at a temperature of about 150° C. to about 400° C., at a pressure below about 15 Torr, under vapor deposition conditions; and
repeating the above steps for multiple cycles until a desired thickness of the silicon nitride film is formed.