Structure and method for alignment marks

摘要

The alignment mark and method for making the same are described. In one embodiment, a semiconductor structure includes a plurality of gate stacks formed on the semiconductor substrate and configured as an alignment mark; doped features formed in the semiconductor substrate and disposed on sides of each of the plurality of gate stacks; and channel regions underlying the plurality of gate stacks and free of channel dopant.

主权项

1. A semiconductor structure, comprising:
a semiconductor substrate having a device region and an alignment region; a plurality of gate stacks formed on the semiconductor substrate in the alignment region and configured as an alignment mark, wherein the plurality of gate stacks include a first gate stack and a second gate stack; doped features formed in the semiconductor substrate and disposed on sides of each of the plurality of gate stacks, wherein the doped features include a source/drain feature continuously extending within the semiconductor substrate from an edge of the first gate stack to an edge of the second gate stack, wherein the doped features have a refractive index of about 3; and channel regions underlying the plurality of gate stacks and free of well dopant, the well dopant being located in the device region.