Anisotropic epitaxial growth of silicon germanium
Generally, examples described herein relate to methods and semiconductor processing systems for anisotropically epitaxially growing a material on a silicon germanium (SiGe) surface. In an example, a surface of silicon germanium is formed on a substrate. Epitaxial silicon germanium is epitaxially grown on the surface of silicon germanium. A first growth rate of the epitaxial silicon germanium is in a first direction perpendicular to the surface of silicon germanium, and a second growth rate of the epitaxial silicon germanium is in a second direction perpendicular to the first direction. The first growth rate is at least 5 times greater than the second growth rate.
1 . A method for semiconductor processing, the method comprising:
epitaxially growing a silicon germanium template layer on a substrate, epitaxially growing the silicon germanium template layer comprising using a first germanium source precursor and a first silicon source precursor, and being performed with a first substrate temperature in a range from 600° C. to 650° C., the silicon germanium template layer having a (100) surface of silicon germanium on a substrate, wherein:
a ratio of a flow rate of the first germanium source precursor and a flow rate of the first silicon source precursor during the epitaxially growing the silicon germanium template layer is between 1:5 and 1.5:1; and
epitaxially growing an epitaxial silicon germanium on the (100) surface of silicon germanium, epitaxially growing the epitaxial silicon germanium comprising using a second germanium source precursor, a dopant precursor comprising boron, and a second silicon source precursor, and being performed at a second substrate temperature, the second germanium source precursor comprising a chlorinated germane gas, wherein:
a ratio of a flow rate of the second germanium source precursor and a flow rate of the second silicon source precursor during the epitaxially growing the epitaxial silicon germanium is between 1:5 and 1.5:1,
a first growth rate of the epitaxial silicon germanium being in a first direction perpendicular to the (100) surface of silicon germanium,
a second growth rate of the epitaxial silicon germanium being in a second direction perpendicular to the first direction, and
the first growth rate being at least 5 times greater than the second growth rate.
2 . The method of claim 1 , wherein the chlorinated germane gas comprises germanium tetrachloride (GeCl 4 ).
3 . The method of claim 1 , wherein the second substrate temperature is in a range from 540° C. to 600° C.
4 . The method of claim 1 , further comprising etching the silicon germanium template layer on the substrate to form a recess, a surface of the recess being the (100) surface of silicon germanium.
5 . The method of claim 1 , wherein the epitaxial silicon germanium forms at least a portion of a source/drain region on a fin on the substrate.
6 . The method of claim 1 , wherein the silicon germanium template layer comprises Si 1−x Ge x where x is in a range from 10 to 30 and the epitaxial silicon germanium comprises Si 1−y Ge y where y is in a range from 30 to 50.
7 . A method for semiconductor processing, the method comprising:
epitaxially growing a silicon germanium template layer on a substrate, epitaxially growing the silicon germanium template layer comprising using a first germanium source precursor and a first silicon source precursor, and being performed with a first substrate temperature in a range from 600° C. to 650° C., the silicon germanium template layer having a (100) surface of silicon germanium, wherein:
a flow rate of the first germanium source precursor is between 10 sccm and 200 sccm,
a flow rate of the first silicon source precursor is between 100 and 1000 sccm, and
a ratio of the flow rate of the first germanium source precursor and the flow rate of the first silicon source precursor during the epitaxially growing the silicon germanium template layer is between 1:5 and 1.5:1; and
epitaxially growing an epitaxial silicon germanium on the (100) surface of silicon germanium, epitaxially growing the epitaxial silicon germanium comprising using a second germanium source precursor, a dopant precursor comprising boron, and a second silicon source precursor, and being performed at a second substrate temperature, the second germanium source precursor comprising a chlorinated germane gas, wherein:
a flow rate of the second germanium source precursor is between 10 sccm and 200 sccm,
a flow rate of the second silicon source precursor is between 100 and 1000 sccm, and
a ratio of the flow rate of the second germanium source precursor and the flow rate of the second silicon source precursor during the epitaxially growing the epitaxial silicon germanium is between 1:5 and 1.5:1.
8 . The method of claim 7 , wherein the chlorinated germane gas is germanium tetrachloride (GeCl 4 ).
9 . The method of claim 7 , wherein the first silicon source precursor comprises silane (SiH 4 ).
10 . The method of claim 7 , wherein epitaxially growing the epitaxial silicon germanium grows the epitaxial silicon germanium in a <100> direction without substantial growth in a <010> direction.
11 . The method of claim 7 , further comprising forming a recess in a silicon germanium layer, the (100) surface of silicon germanium being a bottom surface of the recess.
12 . The method of claim 7 , wherein the second substrate temperature is in a range from 540° C. to 600° C.
13 . The method of claim 7 , wherein the silicon germanium template layer comprises Si 1−x Ge x where x is in a range from 10 to 30 and the epitaxial silicon germanium comprises Si 1−y Ge y where y is in a range from 30 to 50.
14 . The method of claim 7 , wherein the epitaxial silicon germanium forms at least a portion of a source/drain region on a fin on the substrate.
15 . A semiconductor processing system comprising:
a non-transitory computer-readable medium storing instructions that, when executed by a processor, cause a computer system to perform operations of:
epitaxially growing a silicon germanium template layer on a substrate, epitaxially growing the silicon germanium template layer comprising using a first germanium source precursor, a first silicon source precursor, and an etchant gas comprising at least one of hydrochloric acid (HCl), chlorine (Cl 2 ), hydrogen bromide (HBr), or bromine (Br 2 ), and being performed with a first substrate temperature in a range from 600° C. 650° C., the silicon germanium template layer having a (100) surface of silicon germanium, wherein:
a flow rate of the first germanium source precursor is between 10 sccm and 200 sccm,
a flow rate of the first silicon source precursor is between 100 and 1000 sccm, and
a ratio of the flow rate of the first germanium source precursor and the flow rate of the first silicon source precursor during the epitaxially growing the silicon germanium template layer is between 1:5 and 1.5:1; and
epitaxially growing an epitaxial silicon germanium on the (100) surface of silicon germanium, the (100) surface of silicon germanium being on a substrate, epitaxially growing the epitaxial silicon germanium comprising using a second germanium source precursor, a dopant precursor comprising boron, and a second silicon source precursor, and being performed at a second substrate temperature, the second germanium source precursor comprising a chlorinated germane gas, wherein:
a flow rate of the second germanium source precursor is between 10 sccm and 200 sccm,
a flow rate of the second silicon source precursor is between 100 and 1000 sccm, and
a ratio of the flow rate of the second germanium source precursor and the flow rate of the second silicon source precursor during the epitaxially growing the epitaxial silicon germanium is between 1:5 and 1.5:1.
16 . The semiconductor processing system of claim 15 , wherein the chlorinated germane gas is germanium tetrachloride (GeCl 4 ).
17 . The semiconductor processing system of claim 15 , wherein the first silicon source precursor comprises silane (SiH 4 ).
18 . The semiconductor processing system of claim 15 , wherein epitaxially growing the epitaxial silicon germanium grows the epitaxial silicon germanium in a <100> direction without substantial growth in a <010> direction.
19 . The semiconductor processing system of claim 15 , wherein the silicon germanium template layer comprises Si 1-x Ge x where x is in a range from 10 to 30 and the epitaxial silicon germanium comprises Si 1−y Ge y where y is in a range from 30 to 50.