Semiconductor die singulation method

1. A method of singulating semiconductor die from a semiconductor wafer comprising:

providing the semiconductor wafer having a semiconductor material substrate, the semiconductor wafer having a plurality of semiconductor dies formed on the semiconductor wafer and separated from each other by portions of the semiconductor wafer wherein the plurality of semiconductor dies include a dielectric layer covering portions of the plurality of semiconductor dies;

etching a first opening through the dielectric layer and underlying layers to expose a portion of a surface of the semiconductor material substrate while also etching a second opening through the dielectric layer to expose a pad of a semiconductor die of the plurality of semiconductor dies; and

using the dielectric layer as a mask for etching through the first opening to extend a depth of the first opening from the exposed portion of the surface of the semiconductor material substrate into the semiconductor material substrate while also etching through the second opening.

2. The method of claim 1 wherein etching the first opening includes using an etch that selectively etches dielectrics faster than metals.

3. The method of claim 2 wherein using the etch that selectively etches dielectrics includes using an etch that selectively etches dielectrics at least ten times faster than metals.

4. The method of claim 2 wherein using the etch that selectively etches dielectrics includes using an anisotropic etch that selectively etches dielectrics at least ten times faster than metals.

5. The method of claim 1 wherein etching through the first opening includes using an etch that selectively etches silicon faster than metals or dielectrics.

6. The method of claim 5 wherein using the etch that selectively etches silicon faster than metals or dielectrics includes performing the etch using a combination of isotropic and anisotropic etching to etch the silicon at least thirty times faster than metals or dielectrics.

7. The method of claim 5 wherein using the etch that selectively etches silicon faster than metals or dielectrics includes performing the etch using a combination of isotropic and anisotropic etching to etch the silicon at least one hundred times faster than metals or dielectrics.

8. The method of claim 1 further including forming an isolation region near an edge of the semiconductor die, and etching the first opening to extend through the wafer and spaced apart from but adjacent to the isolation region including extending the first opening to undercut portions of the wafer underlying the isolation region.

9. The method of claim 1 further including forming a mask overlying the dielectric layer prior to the step of forming the first opening and the second opening wherein the mask has openings that exposes portions of the dielectric layer and wherein the mask is not a metal layer; and

removing the mask prior to the step of using the dielectric layer as a mask for etching through the first opening.

10. The method of claim 1 further including attaching the semiconductor wafer to a carrier tape prior to the step of etching through the first opening; and again etching through the first opening to further extend the depth of the first opening into the semiconductor wafer.

11. The method of claim 1 wherein the step of providing the semiconductor wafer includes providing the dielectric layer as a layer of polyimide.

12. The method of claim 1 wherein the step of using the dielectric layer as a mask for etching through the first opening includes extending the depth of the first opening to extend completely through the semiconductor wafer.

13. A method of singulating semiconductor die from a semiconductor wafer comprising:

providing the semiconductor wafer having a plurality of semiconductor dies formed on the semiconductor wafer and separated from each other by portions of the semiconductor wafer wherein the plurality of semiconductor dies include a dielectric layer as a top layer; and

forming an isolation region near an edge of a semiconductor die of the plurality of semiconductor dies;

etching a first opening through the dielectric layer spaced apart from but adjacent to the isolation region;

using the dielectric layer as a mask and etching through the first opening to extend a depth of the first opening through the portions of the semiconductor wafer and into the semiconductor wafer wherein the first opening extends from one surface of the semiconductor wafer into the semiconductor wafer thereby creating a space between the plurality of semiconductor dies including undercutting portions of the wafer underlying the isolation region.