Systems and methods for depositing materials on either side of a freestanding film using laser-assisted chemical vapor deposition (LA-CVD), and structures formed using same
Embodiments of the present invention provide systems and methods for depositing materials on either side of a freestanding film using laser-assisted chemical vapor deposition (LA-CVD), and structures formed using same. A freestanding film, which is suspended over a cavity defined in a substrate, is exposed to a fluidic CVD precursor that reacts to form a solid material when exposed to light and/or heat. The freestanding film is then exposed to a laser beam in the presence of the precursor. The CVD precursor preferentially deposits on the surface(s) of the freestanding film.
1. A method of preparing a structure, the method comprising:
providing a film including first and second major film surfaces opposing one another and each suspended over and spanning a cavity defined in a substrate, the film being thin relative to the substrate;
exposing the first major film surface to a first fluidic precursor;
heating the first major film surface with a first laser light in the presence of the first fluidic precursor to a temperature sufficient to convert the first fluidic precursor to a first solid layer disposed on the first major film surface, the first major film surface defining an interface between the first solid layer and the film;
exposing the second major film surface to a second fluidic precursor; and
heating the second major film surface with the first laser light in the presence of the second fluidic precursor to a temperature sufficient to convert the second fluidic precursor to a second solid layer disposed on the second major film surface, the second major film surface defining an interface between the second solid layer and the film;
wherein the film comprises an electrical insulator, wherein the first fluidic precursor comprises a first metalorganic compound, and wherein the first solid layer comprises a first metal, wherein the second fluidic precursor comprises a second metalorganic compound, and wherein the second solid layer comprises a second metal,
wherein the first and second metals are selected independently from the group consisting of: platinum, gold, silver, tungsten, titanium, rhodium, iridium, iron, aluminum, cobalt, copper, and gallium.
2. The method of claim 1 , wherein the first fluidic precursor comprises a gas.
3. The method of claim 1 , wherein forming the cavity comprises:
providing the substrate;
affixing the film to the substrate;
exposing the film and substrate to an etchant;
transmitting a second laser light having a wavelength that is the same as or different than the first laser light through the film,
the etchant etching the substrate in a region defined by the second laser light so as to define the cavity under the film before exposing the first major film surface to the first fluidic precursor.
4. The method of claim 3 , comprising exposing the film to the etchant and to the first fluidic precursor in a single gas cell.
5. The method of claim 1 , wherein a material of the substrate has a higher thermal conductivity than a material of the film.
6. The method of claim 1 , wherein the substrate has an upper surface, and wherein the film is disposed on the upper surface of the substrate.
7. The method of claim 1 , wherein the substrate has an upper surface, and wherein the film is buried below the upper surface of the substrate.
8. The method of claim 1 , wherein the film is substantially continuous.
9. The method of claim 1 , wherein the film comprises silicon oxide, hafnium oxide, silicon nitride, or diamond-like carbon.
10. The method of claim 1 , wherein the substrate comprises silicon, germanium, gallium phosphide, gallium nitride, gallium arsenide, or indium phosphide.