# US 8,150,228 B2 · Acid block for hybrid silicon device processing compatible with low-loss waveguides > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,150,228 B2 - Document ID: US8150228B2 - Status: Granted - Kind: B2 - Application number: 12/346,779 - Filed: 2008-12-30 - Published: 2010-07-01 - Granted: 2012-04-03 - Earliest claimed: 2008-12-30 - Inventors: Richard Jones; Alexander W. Fang - Web page: https://patentgrep.com/patent/US8150228B2 ## CPC - G02B 6/122: Basic optical elements, e.g. light-guiding paths - G02B 6/136: by etching - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract An acid-stop structure for a rib waveguide comprises a fin structure formed between the sidewalls in each rib channel of the rib waveguide, thereby preventing acids and other etchants from flowing down the rib channel and under a die that has been bonded to a wafer. ## Claims ### Claim 1 A device, comprising: a waveguide comprising a rib structure between a first waveguide channel and a second waveguide channel, the first waveguide channel comprising a first sidewall and a second sidewall, the first sidewall of the first waveguide channel comprising a sidewall of the rib structure, the second waveguide channel comprising a first sidewall and a second sidewall, the first sidewall of the second waveguide channel comprising a sidewall of the rib structure, the rib structure comprising a first end, a second end, a length extending in a first direction along the rib structure and a width extending in a direction that is substantially perpendicular to the length, light entering the rib structure at the first end propagates along the rib structure and exits the rib structure at the second end; at least one fin structure formed between the first sidewall and the second sidewall of the first waveguide channel that comprises a height that is substantially equal to a height of the first sidewall and the second sidewall of the first waveguide channel and a width that extends substantially in a same direction as the width of the rib structure; and a fin structure formed between the first sidewall and the second sidewall of the second waveguide channel that corresponds to each fin structure formed between the first sidewall and the second side wall of the first wave guide channel, the fin structure formed between the first sidewall and the second sidewall of the second waveguide channel comprising a width that extends substantially in a same direction as the width of the rib structure, the at least one fin structure in the first waveguide channel and the corresponding fin structure in the second waveguide channel together comprising an optical loss that is less than or equal to about 1.4 dB for a rib structure width that is less than or equal to about 1.80 μm and a fin structure width that is less than or equal to about 2.0 μm. ### Claim 2 (depends on 1) The device according to claim 1, wherein the fin structure in the first waveguide channel and the corresponding fin structure in the second waveguide channel together comprise an optical loss that is less than or equal to about 0.7 dB for a rib structure width that is less than or equal to about 1.80 μm and a fin structure width that is less than or equal to about 1.0 μm. ### Claim 3 (depends on 2) The device according to claim 2, wherein the fin structure in the first waveguide channel and the corresponding fin structure in the second waveguide channel together comprise an optical loss that is less than or equal to about 0.2 dB for a rib structure width that is less than or equal to about 1.80 μm and a fin structure width that is less than or equal to about 0.4 μm. ### Claim 4 (depends on 1) The device according to claim 1, wherein the fin structure in the first waveguide channel and the corresponding fin structure in the second waveguide channel together comprise an optical loss that is less than or equal to about 1.4 dB for a wavelength between about 1.3 μm and about 1.6 μm. ### Claim 5 (depends on 4) The device according to claim 4, wherein the fin structure in the first waveguide channel and the corresponding fin structure in the second waveguide channel together comprise an optical loss that is less than or equal to about 0.35 db for a wavelength between about 1.3 μm and about 1.6 μm. ### Claim 6 (depends on 1) The device according to claim 1, wherein the rib structure and the waveguide channels are formed in a silicon-on-insulator substrate. ### Claim 7 (depends on 6) The device according to claim 6, further comprising a die bonded to the silicon-on-insulator substrate to form a hybrid silicon-optical device. ### Claim 8 (depends on 7) The device according to claim 7, wherein the die is a III-V die. ### Claim 9 A hybrid optical device, comprising: a silicon-on-insulator substrate comprising at least one waveguide, the waveguide comprising a rib structure between a first waveguide channel and a second waveguide channel, the first waveguide channel comprising a first sidewall and a second sidewall, the first sidewall of the first waveguide channel comprising a sidewall of the rib structure, the rib structure comprising a first end and a second end, light entering the rib structure at the first end propagates along the rib structure and exits the rib structure at the second end, the rib structure comprising a length extending in a first direction along the rib structure and a width extending in a direction that is substantially perpendicular to the length, and at least one fin structure formed between the first sidewall and the second sidewall of the first waveguide channel and comprising a width that extends substantially in a same direction as the width of the rib structure, the second waveguide channel comprising a first sidewall and a second sidewall, the first sidewall of the second waveguide channel comprising a sidewall of the rib structure, and at least one fin structure formed between the first sidewall and the second sidewall of the second waveguide channel, the at least one fin structure in the second waveguide channel corresponding to the fin structure in the first waveguide channel and comprising a width that extends substantially in a same direction as the width of the rib structure, the at least one fin structure in the first waveguide channel and the corresponding fin structure in the second waveguide channel together comprising an optical loss that is less than or equal to about 1.4 dB for a rib structure width that is less than or equal to about 1.80 μm and a fin structure width that is less than or equal to about 2.0 μm; and a III-V die bonded to the silicon-on-insulator substrate, the III-IV die comprising circuitry coupled to at least one waveguide. ### Claim 10 (depends on 9) The device according to claim 9, wherein the fin structure in the first rib channel and the corresponding fin structure in the second rib channel together comprise an optical loss that is less than or equal to about 0.7 dB for a rib structure width that is less than or equal to about 1.80 μm and a fin structure width that is less than or equal to about 1.0 μm. ### Claim 11 (depends on 10) The device according to claim 10, wherein the fin structure in the first waveguide channel and the corresponding fin structure in the second waveguide channel together comprise an optical loss that is less than or equal to about 0.2 dB for a rib structure width that is less than or equal to about 1.80 μm and a fin structure width that is less than or equal to about 0.4 μm. ### Claim 12 (depends on 9) The device according to claim 9, wherein the fin structure in the first waveguide channel and the corresponding fin structure in the second waveguide channel together comprise an optical loss that is less than or equal to about 1.4 dB for a wavelength between about 1.3 μm and about 1.6 μm. ### Claim 13 (depends on 12) The device according to claim 12, wherein the fin structure in the first waveguide channel and the corresponding fin structure in the second waveguide channel together comprise an optical loss that is less than or equal to about 0.35 db for a wavelength between about 1.3 μm and about 1.6 μm. ### Claim 14 A device, comprising: a waveguide comprising a rib structure between a first waveguide channel and a second waveguide channel, the rib structure comprising a length extending in a first direction along the rib structure and a width extending in a direction that is substantially perpendicular to the length, the first waveguide channel comprising a first sidewall and a second sidewall, the first sidewall of the first waveguide channel comprising a sidewall of the rib structure, the second waveguide channel comprising a first sidewall and a second sidewall, the first sidewall of the second waveguide channel comprising a sidewall of the rib structure; at least one fin structure formed between the first sidewall and the second sidewall of the first waveguide channel, the at least one fin structure formed between the first sidewall and the second sidewall of the first waveguide channel comprising a height that is substantially equal to a height of the first sidewall and the second sidewall, and comprising a width that extends substantially in a same direction as the width of the rib structure; and at least one fin structure formed between the first sidewall and the second sidewall of the second waveguide channel, the at least one fin structure formed between the first sidewall and the second sidewall of the second waveguide channel comprising a height that is substantially equal to a height of the first sidewall and the second sidewall of the second waveguide channel, and comprising a width that extends substantially in a same direction as the width of the rib structure, a fin structure in the second waveguide channel corresponding to the fin structure in the first waveguide channel, and the fin structure in the first waveguide channel and the corresponding fin structure in the second waveguide channel together comprising an optical loss that is less than or equal to about 1.4 dB for a rib structure width that is less than or equal to about 1.80 μm and a fin structure width that is less than or equal to about 2.0 μm. ### Claim 15 (depends on 14) The device according to claim 14, wherein the fin structure in the first waveguide channel and the corresponding fin structure in the second waveguide channel together comprise an optical loss that is less than or equal to about 0.7 dB for a rib structure width that is less than or equal to about 1.80 μm and a fin structure width that is less than or equal to about 1.0 μm. ### Claim 16 (depends on 15) The device according to claim 15, wherein the fin structure in the first waveguide channel and the corresponding fin structure in the second waveguide channel together comprise an optical loss that is less than or equal to about 0.2 dB for a rib structure width that is less than or equal to about 1.80 μm and a fin structure width that is less than or equal to about 0.4 μm. ### Claim 17 (depends on 14) The device according to claim 14, wherein the fin structure in the first waveguide channel and the corresponding fin structure in the second waveguide channel together comprise an optical loss that is less than or equal to about 1.4 dB for a wavelength between about 1.3 μm and about 1.6 μm.