Methods for designing, fabricating, and predicting shape formations in a material
A method for designing, fabricating, and predicting a desired structure in and/or on a host material through defining etch masks and etching the host material is provided. The desired structure can be micro- or nanoscale structures, such as suspended nanowires and corresponding supporting pillars, and can be defined one layer at a time. Arbitrary desired structures can also be defined and obtained through etching. Further, given the desired structure, a starting structure can be predicted where etching of the starting structure yields the desired structure.
1. A method for fabricating a desired structure in and/or on a host material, comprising:
providing shapes to define the desired structure in and/or on the host material;
defining one or more etch masks in and/or on the host material via addition or removal of a masking material according to each of the shapes;
etching the host material with an etch chemistry to fabricate the desired structure, wherein the etch chemistry selectively etches the host material with respect to the one or more etch masks and selectively etches regions of the host material associated with at least one shape in the desired structure but absent the one or more etch masks; and
iteratively performing the defining and the etching to fabricate the desired structure.
2. The method according to claim 1 , wherein the defining comprises:
providing one or more layers of the host material, wherein particular locations within each of the one or more layers of the host material are doped with the masking material according to each of the shapes.
3. The method according to claim 2 , wherein the defining further comprises:
determining a threshold dose,
wherein dose of the masking material in said particular locations is above the threshold dose.
4. The method according to claim 3 , wherein the determining comprises:
implanting or depositing a plurality of doses in or on a sample area;
etching the sample area for an arbitrarily small amount of time; and
determining a dose for which failure of masking occurs for said arbitrarily small amount of time, thus determining the threshold dose.
5. The method according to claim 2 , wherein the providing one or more layers comprises, for each layer in the one or more layers:
depositing a layer of the host material; and
implanting the masking material into the particular locations of the layer.
6. The method according to claim 5 , wherein the depositing is selected from the group consisting of chemical vapor deposition, thermal evaporation, atomic layer deposition, and sputtering.
7. The method according to claim 2 , wherein the providing one or more layers comprises, for at least one layer in the one or more layers, diffusion of the masking material into the particular locations in the host material.
8. The method according to claim 2 , wherein the host material is silicon, and wherein the providing one or more layers comprises, for each layer, one or more of ion implantation, diffusion, or doped polysilicon growth.
9. The method according to claim 1 , wherein the host material is selected from the group consisting of silicon, silicon carbide, silica, silicon nitride, silicon-germanium, germanium, amorphous carbon, graphite, diamond, carbon nanotubes, organic compounds, photoresists, polydimethylsiloxane (PDMS), and tungsten.
10. The method according to claim 1 , wherein the masking material is selected from the group consisting of silicon, gallium, indium, gold, boron, and aluminum.
11. The method according to claim 1 , wherein the addition or removal of the masking material is performed using ion implantation.
12. The method according to claim 1 , wherein the addition or removal of the masking material is performed using diffusion.
13. The method according to claim 1 , wherein the etch chemistry is a fluorinated etch chemistry.
14. The method according to claim 1 , wherein the etch chemistry includes substrate sidewall passivation.
15. The method according to claim 1 , further comprising, after the etching, removing the masking material.
16. The method according to claim 15 , wherein the removing is selected from the group consisting of wet chemical etching, dry chemical etching, annealing, gettering, kelating, chemical mechanical polishing, physical removal, and cleaning.
17. The method according to claim 1 , further comprising, after the iteratively performing the defining and the etching, removing the masking material.