Methods for forming elongated contact hole ends
Disclosed is a semiconductor processing approach wherein a wafer twist is employed to increase etch rate, at select locations, along a hole or space end arc. By doing so, a finished hole may more closely resemble the shape of the incoming hole end. In some embodiments, a method may include providing an elongated contact hole formed in a semiconductor device, and etching the elongated contact hole while rotating the semiconductor device, wherein the etching is performed by an ion beam delivered at a non-zero angle relative to a plane defined by the semiconductor device. The elongated contact hole may be defined by a set of sidewalls opposite one another, and a first end and a second end connected to the set of sidewalls, wherein etching the elongated contact hole causes the elongated contact hole to change from an oval shape to a rectangular shape.
1. A method, comprising:
providing an elongated contact hole formed in a semiconductor device; and
etching the elongated contact hole while rotating the semiconductor device, wherein the etching is performed by an ion beam delivered at a non-zero angle relative to a plane defined by the semiconductor device, and wherein the elongated contact hole is defined by:
a set of sidewalls opposite one another; and
a first end and a second end connected to the set of sidewalls, wherein etching the elongated contact hole causes the elongated contact hole to change from an oval shape to a rectangular shape.
2. The method of claim 1 , further comprising etching a set of shoulder areas between the set of sidewalls and an apex of the first end and the second end, wherein etching the set of shoulder areas causes the set of sidewalls to extend parallel to one another.
3. The method of claim 2 , wherein an angle of incidence and an ion flux are optimized at the first and second ends of the contact hole to cause the set of shoulder areas to be etched faster than the apex.
4. The method of claim 3 , wherein the angle of incidence is determined based on the non-zero angle of the ion beam and an angle of rotation of the semiconductor device about an axis of rotation, wherein the axis of rotation extends perpendicular to the plane defined by the semiconductor device.
5. The method of claim 3 , wherein the angle of incidence varies as the semiconductor device is rotated.
6. The method of claim 1 , further wherein the non-zero angle of the ion beam is constant as the semiconductor device is rotated.
7. The method of claim 1 , wherein the etching is performed at just the first end or the second end of the elongated contact hole.
8. A method of forming a contact hole in a semiconductor device, comprising:
providing the contact hole extending through the semiconductor device, wherein the contact hole comprises:
a set of sidewalls opposite one another; and
a first end and a second end connected to the set of sidewalls, wherein the contact hole has an oval shape; and
etching the contact hole using an ion beam delivered to the contact hole at a non-zero angle relative to a plane defined by a top surface of the semiconductor device, wherein the etching is performed while the semiconductor rotates about an axis of rotation extending perpendicular to the plane, and wherein the etching causes at least one end of the contact hole to change from the oval shape to a squared shape.
9. The method of claim 8 , further comprising etching a set of shoulder areas between the set of sidewalls and an apex of the first end and the second end, wherein etching the set of shoulder areas causes the set of sidewalls to extend parallel to one another.
10. The method of claim 9 , wherein an angle of incidence and an ion flux are optimized at the first end and the second end of the contact hole to cause the set of shoulder areas to be etched faster than the apex.
11. The method of claim 10 , wherein the angle of incidence is determined based on the non-zero angle of the ion beam and an angle of rotation of the semiconductor device about the axis of rotation.
12. The method of claim 10 , wherein the angle of incidence changes as the semiconductor device is rotated.
13. The method of claim 8 , wherein the non-zero angle of the ion beam is constant as the semiconductor device is rotated.
14. The method of claim 8 , wherein the etching is performed at just the first end or the second end of the contact hole.
15. A method of forming an elongated contact hole in a semiconductor device, comprising:
providing the elongated contact hole extending through the semiconductor device, wherein the elongated contact hole has an oval shape, and wherein the elongated contact hole comprises:
a set of sidewalls opposite one another;
a first end and a second end connected to the set of sidewalls; and
a set of shoulder areas between the set of sidewalls and an apex of the first end or the second end; and
etching the elongated contact hole while rotating the semiconductor device about an axis of rotation extending perpendicular to a plane defined by a top surface of the semiconductor device, wherein the etching is performed by an ion beam delivered at a non-zero angle relative to the plane, and wherein the etching causes a material of the semiconductor device at the set of shoulder areas to be etched faster than the material of the semiconductor device at the apex.
16. The method of claim 15 , wherein etching the set of shoulder areas causes the set of sidewalls to extend parallel to one another.
17. The method of claim 15 , wherein an angle of incidence and an ion flux are optimized at the first end and the second end of the contact hole to cause the set of shoulder areas to be etched faster than the apex.
18. The method of claim 17 , wherein the angle of incidence is determined based on the non-zero angle of the ion beam and an angle of rotation of the semiconductor device about the axis of rotation.
19. The method of claim 17 , wherein the angle of incidence varies as the semiconductor device is rotated.
20. The method of claim 15 , wherein the non-zero angle of the ion beam is constant as the semiconductor device is rotated.