Semiconductor ICF target processing
A method of manufacturing a semiconductor ICF target is described. On an n-type silicon wafer a plurality of hard mask layers are etched to a desired via pattern. Then isotropically etching hemispherical cavities, lithographically patterning the hard mask layers, conformally depositing ablator/drive material(s) and shell layer material(s), inserting hollow silicon dioxide fuel spheres in the hemisphere cavities, thermally bonding a mating wafer with matching hemisphere cavities and etching in ethylene diamine-pryrocatechol-water mixture to selectively remove n-type silicon and liberate the spherical targets.
1. A process for manufacturing a plurality of individual spherical devices in parallel from a wafer of semiconductor material, comprising:
creating a first wafer by:
depositing one or more hard mask films upon a single-crystal n-type silicon substrate;
applying a uniform coat of photoresist pattern on top of the one or more hard mask films, wherein the first wafer is rotating as the uniform coat of photoresist pattern is applied;
etching through the one or more hard mask films with vias, wherein the vias range in diameter from 1 μm to 1 mm;
forming hemispherical cavities using an isotropic dry etch of the n-type silicon substrate having one or more hard mask films, wherein the hemispherical cavities range in diameter from 100 μm to 5 cm;
using a Chemical Mechanical Planarization (CMP) process to polish and remove one or more of the hard mask films;
incorporating a p-type dopant on a surface of the hemispherical cavities;
placing hollow silicon dioxide fuel spheres within the hemispherical cavity; and
filling the hollow silicon dioxide fuel spheres with a fusion fuel mixture,
creating a second wafer by repeating the above steps of creating a first wafer, wherein the second wafer has the same pattern of hemispherical cavities as the first wafer;
mating the first and second wafers together;
adhesively bonding the first and second wafers together;
etching to selectively remove what remains from the single-crystal n-type silicon substrate to liberate a spherical device; and
repeating all of the above steps that produce the plurality of individual spherical devices, in parallel.
2. The process of claim 1 , wherein said single-crystal n-type silicon substrate is customized to a thickness ranging from approximately 500 to 5 cm.
3. The process of claim 2 , wherein the plurality of hard mask films are composed of one or more of the following materials: silicon dioxide, silicon nitride and chromium.
4. The process of claim 3 , wherein the plurality of hard mask films are each customized to a thickness ranging from approximately 200 Å to 100,000 Å.
5. The process of claim 4 , further comprising:
isotropically etching the hemispherical cavities with a sulfur hexafluoride dry etch.
6. The process of claim 5 , further comprising:
using thermally diffuse boron atoms in the p-type doping of the surface of the hemispherical cavity.
7. The process of claim 6 , wherein the p-type doping of the surface of the hemispherical cavity is performed to a depth of approximately 1-200 μm for the thermally diffuse boron atoms.
8. The process of claim 7 , further comprising;
conformally depositing a shell layer on top of an ablator/drive layer on top of a surface of the hemispherical cavities; and
removing any excess from the deposition of shell layer and ablator/drive layer by a planarization polish.