Methods of forming superlattice structures using nanoparticles
Methods and systems for forming structures including a superlattice of silicon-containing epitaxial layers using nanoparticles. Exemplary methods can include forming nanoparticles in situ and depositing the nanoparticles onto a substrate surface to thereby form the epitaxial layers.
1 . A method of forming a superlattice structure, the method comprising:
providing a substrate within a reaction chamber;
forming a first silicon-containing epitaxial layer by providing first silicon-containing nanoparticles to a surface of the substrate, wherein a substrate bias power source attracts positively charged nanoparticles of the first silicon-containing nanoparticles toward the substrate by imparting a net negative bias on a substrate support within the reaction chamber;
forming a second silicon-containing epitaxial layer overlying the first silicon-containing epitaxial layer by providing second silicon-containing nanoparticles; and
repeating the steps of forming the first silicon-containing epitaxial layer and forming the second silicon-containing epitaxial layer to form a superlattice,
wherein a composition of the first silicon-containing epitaxial layer differs from a composition of the second silicon-containing epitaxial layer.
2 . The method according to claim 1 , wherein the step of forming the first silicon-containing epitaxial layer comprises forming an intrinsic or doped silicon layer.
3 . The method according to claim 1 , wherein the step of forming the second silicon-containing epitaxial layer comprises forming a layer comprising silicon germanium.
4 . The method according to claim 1 , wherein one of the first silicon-containing epitaxial layer and the second silicon-containing epitaxial layer can be selectively etched relative to the other of the first silicon-containing epitaxial layer and the second silicon-containing epitaxial layer.
5 . The method according to claim 1 , wherein the step of providing the first silicon-containing nanoparticles comprises forming the first silicon-containing nanoparticles within the reaction chamber.
6 . The method according to claim 5 , wherein the step of providing the first silicon-containing nanoparticles within the reaction chamber comprises a first plasma-enhanced chemical vapor deposition process.
7 . The method according to claim 6 , wherein the step of providing the second silicon-containing nanoparticles comprises forming the second silicon-containing nanoparticles within the reaction chamber.
8 . The method according to claim 7 , wherein the step of providing the second silicon-containing nanoparticles within the reaction chamber comprises a second plasma-enhanced chemical vapor deposition process.
9 . The method according to claim 8 , wherein one or more of the first plasma-enhanced chemical vapor deposition process or the second plasma-enhanced chemical vapor deposition process comprises forming a plasma using an inductively-coupled plasma apparatus.
10 . The method according to claim 9 , further comprising a purge step between the steps of forming the first silicon-containing epitaxial layer and forming the second silicon-containing epitaxial layer.
11 . The method according to claim 1 , wherein the substrate is biased during one or more of the steps of forming the first silicon-containing epitaxial layer and forming the second silicon-containing epitaxial layer.
12 . The method according to claim 1 , further comprising a step of forming a carbon-containing layer between the steps of forming the first silicon-containing epitaxial layer and forming the second silicon-containing epitaxial layer.
13 . The method according to claim 12 , wherein the carbon-containing layer comprises graphene.
14 . The method according to claim 1 , wherein one or more of the first silicon-containing epitaxial layer and the second silicon-containing epitaxial layer comprises a silicon alloy.
15 . The method according to claim 1 , wherein one or more of the first silicon-containing epitaxial layer and the second silicon-containing epitaxial layer comprises a dopant.
16 . The method according to claim 1 , wherein the substrate is heated using one or more of a susceptor heater, an infrared lamp, a process gas, and a heat exchanger.
17 . The method according to claim 1 , further comprising providing a localized energy to a portion of the substrate to selectively form one or more of the first silicon-containing epitaxial layer and the second silicon-containing epitaxial layer.
18 . The method according to claim 1 , further comprising etching the superlattice to form a superlattice feature.
19 . The method according to claim 18 , further comprising a step of selectively etching one of the first silicon-containing epitaxial layer and the second silicon-containing epitaxial layer.
20 . The method according to claim 1 , wherein the first silicon-containing epitaxial layer consists essentially of silicon and the second silicon-containing epitaxial layer consists essentially of silicon germanium.
21 . A superlattice structure formed according to the method according to claim 1 .