Method of aligning structures on opposite sides of a wafer
AssigneeDALSA Semiconductor Inc.
InventorLuc Ouellet
Life of this patent
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Abstract
A method is disclosed for aligning structures on first and second opposite sides of a wafer. First one or more transparent islands are formed on the first side of the wafer at an alignment location. The transparent islands have an exposed front side and a rear side embedded in the wafer. At least one alignment mark is formed on the front side of the transparent island. An anisotropic etch is performed through the second side of said the to form an opening substantially reaching the back side of the transparent island. A precise alignment is then carried out on the alignment mark through the opening and the transparent island. In this way a very precise alignment can be carried out on the back side of the wafer for manufacturing MEMS structures.
Claims24
A method of aligning structures on first and second opposite sides of a wafer, comprising the steps of:
- forming at least one transparent island on the first side of said wafer at an alignment location, said transparent island having an exposed front side and a rear side embedded in said wafer;
- providing at least one alignment mark on the exposed front side of said transparent island;
- performing an anisotropic etch through the second side of said wafer to form a window opening substantially reaching the rear side of said transparent island with said transparent island acting as an etch stop;
- and
- carrying out a precise alignment on said alignment mark through said window opening and said transparent island.
A method of aligning structures on first and second opposite sides of a silicon wafer, comprising the steps of:
- locally oxidizing portions of the first side of said wafer to form at least one transparent island having an exposed front side and a rear side embedded in said wafer;
- patterning at least one alignment mark on the front side of said at least one transparent island;
- performing an anisotropic etch through the second side of said wafer to form a window opening substantially reaching the rear side of said transparent island using said transparent island as an etch stop;
- and
- carrying out a precise alignment on said alignment mark through said window opening and said transparent island.
Dependencies are inferred from the claim text.