Method for achieving uniform etch depth using ion implantation and a timed etch
A method of performing a timed etch of a material to a precise depth is provided. In this method, ion implantation of the material is performed before the timed etch. This ion implantation process substantially enhances the etch rate of the material within a precisely controlled depth range corresponding to the range of implantation-induced damage. By using the ion implantation, the variation in vertical etch depth can be reduced by a factor approximately equal to the etch rate of the damaged material divided by the etch rate of the undamaged material. The vertical etch depth can be used to provide a vertical dimension of a non-planar semiconductor device. Minimizing vertical device dimension variations on a wafer can reduce device and circuit performance variations, which is highly desirable.
1. A wafer comprising:
ridged semiconductor material subjected to a first ion implantation, thereby damaging the ridged semiconductor material;
an isolation material formed between ridges of the ridged semiconductor material, the isolation material subjected to the first ion implantation, thereby damaging the isolation material, and then etched to a precise depth having a variation less than 10% across the wafer; and
a dielectric layer disposed on a top surface of each said ridge, and extending down each side surface of each said ridge to said isolation material.
2. The wafer of claim 1 , wherein the isolation material is a dielectric.
3. The wafer of claim 1 , wherein the isolation material is silicon dioxide.
4. The wafer of claim 1 , wherein the isolation material is a field oxide.
5. The wafer of claim 1 , wherein the ridged semiconductor material forms a transistor with a segmented channel region.
6. The wafer of claim 1 , wherein the ridged semiconductor material forms an inverted T-channel field-effect transistor (ITFET).
7. The wafer of claim 1 , wherein the ridged semiconductor material forms a capacitor.
8. The wafer of claim 1 , wherein the ion implantation includes argon.
9. The wafer of claim 1 , wherein the ion implantation includes germanium.
10. The wafer of claim 1 , further comprising a gate disposed on said dielectric layer and extending below the top surfaces of said ridges and between said ridges to said isolation material.