TWO-STEP HARDMASK FABRICATION METHODOLOGY FOR SILICON WAVEGUIDES
First Claim
1. A method of making a silicon waveguide structure, the method comprising:
- depositing a hardmask layer on a substrate having a silicon layer on an oxide layer;
etching the hardmask layer to provide a patterned hardmask defining patterns for a waveguide and at least one other structure;
etching partway down the silicon layer with the patterned hardmask in place to form at least part of the waveguide and the at least one other structure;
patterning a slab of the at least one other structure; and
etching the remainder of the silicon layer down to the oxide layer with the patterned hardmask in place, thereby defining the slab of the at least one other structure and more of the waveguide.
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Abstract
Techniques are disclosed for efficiently fabricating semiconductors including waveguide structures. In particular, a two-step hardmask technology is provided that enables a stable etch base within semiconductor processing environments, such as the CMOS fabrication environment. The process is two-step in that there is deposition of a two-layer hardmask, followed by a first photolithographic pattern, followed by a first silicon etch, then a second photolithographic pattern, and then a second silicon etch. The process can be used, for example, to form a waveguide structure having both ridge and channel configurations, or a waveguide (ridge and/or channel) and a salicide heater structure, all achieved using the same hardmask. The second photolithographic pattern allows for the formation of the lower electrical contacts to the waveguides (or other structures) without a complicated rework of the hardmask.
78 Citations
20 Claims
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1. A method of making a silicon waveguide structure, the method comprising:
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depositing a hardmask layer on a substrate having a silicon layer on an oxide layer; etching the hardmask layer to provide a patterned hardmask defining patterns for a waveguide and at least one other structure; etching partway down the silicon layer with the patterned hardmask in place to form at least part of the waveguide and the at least one other structure; patterning a slab of the at least one other structure; and etching the remainder of the silicon layer down to the oxide layer with the patterned hardmask in place, thereby defining the slab of the at least one other structure and more of the waveguide. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of making a silicon waveguide structure, the method comprising:
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depositing a hardmask layer on a substrate having a silicon layer on an oxide layer, wherein the hardmask layer includes a top layer that acts as a hardmask and a polish stop for chemical-mechanical planarization (CMP), and a bottom layer that acts as an etch stop for subsequent removal of the top hardmask layer; etching the hardmask layer with a pattern of photoresist in place to provide a patterned hardmask defining waveguide patterns for a channel waveguide and a ridge waveguide; etching partway down the silicon layer with the patterned hardmask and photoresist in place to form at least part of the channel waveguide and the ridge waveguide; patterning a slab of the ridge waveguide using photoresist; and etching the remainder of the silicon layer down to the oxide layer with the patterned hardmask in place, thereby defining the slab of the ridge waveguide and more of the channel waveguide. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A method of making a silicon waveguide structure, the method comprising:
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depositing a hardmask layer on a substrate having a silicon layer on an oxide layer, wherein the hardmask layer includes a top nitride layer and a bottom oxide layer; etching the hardmask layer to provide a patterned hardmask defining waveguide patterns for a channel waveguide and a ridge waveguide; etching partway down the silicon layer with the patterned hardmask in place to form at least part of the channel waveguide and the ridge waveguide; patterning a slab of the ridge waveguide; etching the remainder of the silicon layer down to the oxide layer with the patterned hardmask in place, thereby defining the slab of the ridge waveguide and more of the channel waveguide; depositing a cladding layer over the ridge and channel waveguides; and planerizing the cladding layer using a CMP process, wherein the CMP process stops on or partially removes the top nitride layer. - View Dependent Claims (19, 20)
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Specification