Ion beam etch without need for wafer tilt or rotation
Various embodiments herein relate to methods and apparatus for etching feature on a substrate. In a number of embodiments, no substrate rotation or tilting is used. While conventional etching processes rely on substrate rotation to even out the distribution of ions over the substrate surface, various embodiments herein achieve this purpose by moving the ion beams relative to the ion source. Movement of the ion beams can be achieved in a number of ways including electrostatic techniques, mechanical techniques, magnetic techniques, and combinations thereof.
1. An ion beam etching apparatus for etching material on semiconductor substrates, the apparatus comprising:
a reaction chamber;
a substrate support in the reaction chamber;
an ion source comprising:
a plasma region for generating and/or maintaining a plasma, and
an ion extractor positioned proximate the plasma region, the ion extractor comprising:
a first electrode, a second electrode, and a third electrode, each of the first, second, and third electrodes comprising a plurality of apertures therein, wherein the third electrode is an off-center aperture electrode, and all of the apertures in the third electrode being offset from apertures in the first and second electrodes, and
a power supply configured to supply a bias potential to one or more of the first electrode, second electrode, and third electrode,
wherein the ion extractor is configured to generate a plurality of ion beams emanating from the plurality of apertures in the first, second, and third electrodes; and
a controller having instructions to:
(a) generate the ion beams and apply a bias to the off-center aperture electrode to thereby deflect a direction of the ion beam trajectories to a non-normal angle with respect to a lowermost electrode of the ion extractor, the lowermost electrode being one of the first electrode, second electrode, and third electrode, and
(b) vary the bias applied to the off-center aperture electrode to thereby alter the direction of the ion beam trajectories such that the ion beams move with respect to the orientation of the substrate during etching, wherein the direction of each ion beam trajectory is along the centerline of the ion beam.
2. The apparatus of claim 1 , wherein the apertures in the third electrode are offset from apertures in the first and second electrodes in a first direction, further comprising a fourth electrode that is an off-center aperture electrode with apertures that are offset from apertures in the first and second electrodes in a second direction, wherein the first direction is different from the second direction.
3. The apparatus of claim 1 , wherein the substrate support is not configured to tilt the substrate during etching.
4. The apparatus of claim 1 , wherein the substrate support is not configured rotate the substrate during etching.
5. The apparatus of claim 1 , further comprising a hollow cathode emitter electrode.
6. The apparatus of claim 1 , further comprising an injection head comprising a reactant delivery region and a vacuum region that (i) is at least partially separated from the reactant delivery region and (ii) substantially surrounds and/or abuts the reactant delivery region, wherein the injection head provides reactants within the reactant delivery region at a local high pressure, wherein the controller further comprises instructions to maintain the reaction chamber below a processing pressure, wherein the local high pressure is at least about 10 times higher than the processing pressure.
7. The apparatus of claim 1 , wherein ion beams emanating from apertures in the lowermost electrode emanate parallel to one another.
8. A method for etching material on a semiconductor substrate, the method comprising:
(a) generating a plasma;
(b) generating ion beams from the plasma using an ion source comprising a first electrode, a second electrode, and a third electrode, each electrode having a plurality of apertures therein, wherein the third electrode is an off-center aperture electrode, and all of the apertures in the third electrode being offset from apertures in the first and second electrodes;
(c) applying a bias to the off-center aperture electrode to thereby deflect a direction of the ion beam trajectories to a non-normal angle with respect to a lowermost electrode of the ion source, the lowermost electrode being one of the first electrode, second electrode, and third electrode; and
(d) varying the bias applied to the off-center aperture electrode to thereby alter the direction of the ion beam trajectories such that the ion beams move with respect to the orientation of the ion source during etching, wherein the direction of each ion beam trajectory is along the centerline of the ion beam.
9. The method of claim 8 , wherein the substrate does not rotate during etching.
10. The method of claim 8 , wherein the substrate does not tilt during etching.