Method of selectively forming phosphorous-doped epitaxial material on a surface
Methods and systems for selectively forming phosphorus-doped epitaxial material. The methods can be used to selectively form the phosphorus-doped epitaxial material within a gap from the bottom upward. Exemplary methods can be used to, for example, form source and/or drain regions in field effect transistor devices, such as in gate-all-around field effect transistor devices.
1 . A method of selectively forming P-doped monocrystalline material on a surface of a substrate, the method comprising steps of:
providing a substrate within a reaction chamber, the substrate comprising a bottom surface comprising a first crystallographic orientation and a sidewall surface, which is perpendicular to the bottom surface, comprising a second crystallographic orientation, the bottom surface and the sidewall surface comprising the same material;
performing a cyclical deposition process to selectively form P-doped epitaxial material overlying the bottom surface, relative to the sidewall surface, the cyclical deposition process comprising one or more deposition cycles, each deposition cycle comprising:
forming first P-doped epitaxial material overlying the bottom surface and overlying a first portion of the sidewall surface extending from the bottom surface to a point of the sidewall surface at a height of the first P-doped epitaxial material in a vertical direction and forming second P-doped epitaxial or P-doped non-epitaxial material overlying a second portion of the sidewall surface extending vertically from the point of the sidewall surface at the height of the first P-doped epitaxial material in the vertical direction;
forming first intrinsic epitaxial material overlying an exposed top surface of the first P-doped epitaxial material overlying the bottom surface and forming second intrinsic epitaxial or intrinsic non-epitaxial material overlying the second P-doped epitaxial or P-doped non-epitaxial material overlying the sidewall surface and extending vertically from a top surface of the first intrinsic epitaxial material in the vertical direction; and
selectively etching the second intrinsic epitaxial or intrinsic non-epitaxial material and the second P-doped epitaxial or P-doped non-epitaxial material overlying the sidewall surface, relative to the first intrinsic epitaxial material and the first P-doped epitaxial material overlying the bottom surface,
wherein the bottom surface consists of a Si{100} crystal facet, and
wherein the sidewall surface comprises one or more of a Si{110} crystal facet and a higher order silicon crystal facet that is perpendicularly oriented to a Si{100} crystal facet.
2 . The method according to claim 1 , wherein the substrate comprises a feature, the feature comprising the bottom surface and the sidewall surface.
3 . The method according to claim 2 , wherein an aspect ratio of the feature is greater than 1 or greater than 0.6 or between 0.3 and 1 or between 0.5 and 0.7.
4 . The method according to claim 2 , wherein the feature comprises a gap.
5 . The method according to claim 1 , wherein a temperature within the reaction chamber during one or more of the steps is less than 450° C.
6 . The method according to claim 1 , wherein the step of forming the first P-doped epitaxial material overlying the bottom surface comprises providing a silicon precursor comprising a silane.
7 . The method according to claim 6 , wherein the silicon precursor is selected from one or more of the group consisting of disilane and trisilane.
8 . The method according to claim 1 , wherein the step of selectively etching comprises providing an etchant comprising chlorine (Cl 2 ).
9 . The method according to claim 1 , wherein the step of selectively etching further comprises providing a carrier gas and an etchant, wherein a flowrate of the carrier gas and a flowrate of the etchant is between 50 and about 200 or between about 30 and about 1300.
10 . The method according to claim 1 , wherein a thickness of the first intrinsic epitaxial material overlying the first P-doped epitaxial material is between about 2 nm and about 10 nm.
11 . The method according to claim 1 , wherein a thickness of the first P-doped epitaxial material is between about 2 nm and about 10 nm.
12 . The method according to claim 1 , wherein a concentration of phosphorus in the first P-doped epitaxial material is between about 5e19 cm −3 and about 5e21 cm −3 .
13 . The method according to claim 1 , wherein the second P-doped epitaxial or P-doped non-epitaxial material overlying the sidewall surface is removed during each deposition cycle.
14 . The method according to claim 1 , wherein the step of forming first intrinsic epitaxial material overlying the first P-doped epitaxial material comprises providing a silicon precursor selected from the group consisting of disilane and trisilane.
15 . The method according to claim 14 , wherein the silicon precursor provided during the step of forming the first P-doped epitaxial material overlying the bottom surface and the silicon precursor provided during the step of forming the first intrinsic epitaxial material overlying the first P-doped epitaxial material comprises the same silicon precursor.
16 . The method according to claim 1 , comprising filling a gap with the first P-doped epitaxial material from a bottom of the gap upwards.
17 . A method of forming a gate-all-around device comprising the method of claim 1 .
18 . A system for performing the method of claim 1 , wherein each step of the method is performed within the reaction chamber.
19 . The method according to claim 1 , wherein the first intrinsic epitaxial material serves as a cap that protects the first P-doped epitaxial material overlying the bottom surface during the selectively etching of the second intrinsic epitaxial or intrinsic non-epitaxial material and the second P-doped epitaxial or P-doped non-epitaxial material overlying the sidewall surface.
20 . A method of selectively forming P-doped monocrystalline material on a surface of a substrate, the method comprising steps of:
providing a substrate within a reaction chamber, the substrate comprising a bottom surface comprising a first crystallographic orientation and a sidewall surface comprising a second crystallographic orientation, the bottom surface and the sidewall surface comprising the same material;
performing a cyclical deposition process to selectively form P-doped epitaxial material overlying the bottom surface, relative to the sidewall surface, the cyclical deposition process comprising one or more deposition cycles, each deposition cycle comprising:
forming first P-doped epitaxial material overlying the bottom surface and forming second P-doped epitaxial or P-doped non-epitaxial material overlying the sidewall surface;
forming first intrinsic epitaxial material overlying the first P-doped epitaxial material overlying the bottom surface and forming second intrinsic epitaxial or intrinsic non-epitaxial material overlying the second P-doped epitaxial or P-doped non-epitaxial material overlying the sidewall surface above the first intrinsic epitaxial material; and
selectively etching the second intrinsic epitaxial or intrinsic non-epitaxial material and the second P-doped epitaxial or P-doped non-epitaxial material overlying the sidewall surface, relative to the first intrinsic epitaxial material and the first P-doped epitaxial material overlying the bottom surface,
wherein the first intrinsic epitaxial material serves as a cap that protects the first P-doped epitaxial material overlying the bottom surface during the selectively etching,
wherein the bottom surface consists of a Si{100} crystal facet,
wherein the sidewall surface comprises one or more of a Si{110} crystal facet and a higher order silicon crystal facet that is perpendicularly oriented to a Si{100} crystal facet, and
wherein the first intrinsic epitaxial material serves as a cap that protects the first P-doped epitaxial material overlying the bottom surface during the selectively etching of the second intrinsic epitaxial or intrinsic non-epitaxial material and the second P-doped epitaxial or P-doped non-epitaxial material overlying the sidewall surface.