EP0356190A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Photonic-integrated-circuit fabrication process
Assignee: AT&T Inc
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Filing: 1989-08-21
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Granted: —
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Expires: 2009-08-21
Abstract
Abstract An improved process for fabricating photonic circuits is disclosed. The inventive process starts with a growth of a base wafer comprising a stack of epitaxial layers of various materials. At least a portion of each of the material layers will ultimately be a functioning part of any of a number of devices which will form the PIC or will serve a role in at least one of the fabrication processing steps. Specific inventive processing steps are addressed to (1) interconnecting passive waveguides, active devices, and grating filtering regions without the substantial optical discontinuities which appear in the prior art, and (2) etching continuous waveguide mesas to different depths in different regions of the PIC so as to optimize the performance of each PIC device.
Inventors
- 👤 Thomas Lawson Koch
- 👤 Uziel Koren
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 10:22
CPC Classifications
H; H01; H01S; H01S5/00; H01S5/02; H01S5/026; H01S5/0262; H01S5/0264; G; G02; G02B; G02B6/00; G02B6/10; G02B6/12; G02B6/122; G02B6/124; G02B6/13; G02B6/136; H10; H10D; H10D84/00; H10D84/01; H10D84/02; H10D84/05; H01S5/10; H01S5/12; H01S5/1231; Y; Y10; Y10S; Y10S148/00; Y10S148/095; Y10S148/106; Y10S438/00; Y10S438/942
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
262 words
A method of fabricating photonic integrated circuits comprising epitaxially growing a stack of numerous layers of semiconductor materials, at least two of which differ in either material composition or doping level or doping type, at least a portion of each of the material layers serving a function in at least one of the devices which will comprise the PIC or in at least one of the PIC fabrication steps, CHARACTERIZED IN THAT (1) the stack is selectively etched to define areas of specific layer combinations, at least a portion of some of such areas ultimately forming devices which will comprise the PIC, the specific layer combination of each of such areas being appropriate for each of such devices. (2) a first, stripe geometry, mask is subsequently deposited to protect the region of the remaining stack underlying the mask from subsequent etching. (3) unmasked portions of the stack are subsequently etched, (4) a second mask, at least a portion of which overlies the first mask, and at least a portion of the overlying region of said overlying mask having a width larger than that of the first, stripe geometry, mask, is subsequently deposited to protect the region of the remaining stack underlying either the first or second mask from subsequent etching. (5) unmasked portions of the stack are subsequently etched, whereby portions of the stack which underlie only the second mask are less deeply etched than portions of the stack which do not underlie either of the masks, and a stripe geometry mesa is thereby formed with regions of deep and shallow sidewalls.
Claim 2
Independent Claim
262 words
A method of fabricating photonic integrated circuits comprising epitaxially growing a stack of numerous layers of semiconductor materials, at least two of which differ in either material composition or doping level or doping type, at least a portion of each of the material layers serving a function in at least one of the devices which will comprise the PIC or in at least one of the PIC fabrication steps, CHARACTERIZED IN THAT (1) the stack is selectively etched to define areas of specific layer combinations, at least a portion of some of such areas ultimately forming devices which will comprise the PIC, the specific layer combination of each of such areas being appropriate for each of such devices. (2) a first, stripe geometry, mask is subsequently deposited to protect the region of the remaining stack underlying the mask from subsequent etching. (3) unmasked portions of the stack are subsequently etched, (4) a second mask, at least a portion of which overlies the first mask, and at least a portion of the overlying region of said overlying mask having a width larger than that of the first, stripe geometry, mask, is subsequently deposited to protect the region of the remaining stack underlying either the first or second mask from subsequent etching. (5) unmasked portions of the stack are subsequently etched, whereby portions of the stack which underlie only the second mask are less deeply etched than portions of the stack which do not underlie either of the masks, and a stripe geometry mesa is thereby formed with regions of deep and shallow sidewalls.
Claim 3
Independent Claim
88 words
A method of etching a first, uniformly patterned, surface adjacent to a second surface which remains unetched during the etching step comprising forming a second-surface masking material over the second surface, and exposing both first and second surfaces to an etchant, CHARACTERIZED IN THAT the said second-surface masking material and the said first surface etch at substantially the same rate when exposed to the said etchant, whereby the said first surface is unformly patterned without any substantial discontinuity in the pattern in regions adjacent to the second surface.
Claim 4
Independent Claim
88 words
A method of etching a first, uniformly patterned, surface adjacent to a second surface which remains unetched during the etching step comprising forming a second-surface masking material over the second surface, and exposing both first and second surfaces to an etchant, CHARACTERIZED IN THAT the said second-surface masking material and the said first surface etch at substantially the same rate when exposed to the said etchant, whereby the said first surface is unformly patterned without any substantial discontinuity in the pattern in regions adjacent to the second surface.
Claim 5
Dependent Claim
40 words
The method of claim 2 further comprising forming a corrugated mask over the first surface prior to etching whereby the first surface is uniformly patterned with a corrugation appropriate for use as a grating in optical filtering or reflector devices.
Claim 6
Dependent Claim
22 words
The method of claim 3 whereby the corrugated mask is formed over both the first surface and the second surface masking material.
Claim 7
Independent Claim
11 words
The method of claims 2-4 wherein the surfaces are semiconductor materials.
Claim 8
Dependent Claim
19 words
The method of claim 5 wherein said semiconductor materials are selected from the group consisting of III-V compound semiconductors.
Claim 9
Dependent Claim
11 words
The method of claim 6 wherein the semiconductor material comprises InGaAsP.
Claim 10
Independent Claim
16 words
The method of claims 2-4 wherein the second surface masking material is an epitaxially grown material.
Claim 11
Dependent Claim
13 words
The method of claim 8 wherein the epitaxially grown material is a semiconductor.
Claim 12
Independent Claim
22 words
The method of claims 2-4 wherein the said first and second surfaces comprises InGaAsP and the second surface masking material comprises InP.
Claim 13
Dependent Claim
60 words
The method of claim 1 wherein additional epitaxial materials are subsequently grown, said subsequently grown epitaxial materials serving as current blocking layers in regions adjacent to those regions which will ultimately form devices to which electric fields will be applied, and said same subsequently grown epitaxial materials serving as cladding layers for regions which will ultimately form optical waveguide cores.
Claim 14
Dependent Claim
13 words
The method of claim 11 wherein subsequently grown epitaxial material comprises semi-insulating materials.
Claim 15
Dependent Claim
18 words
The method of claim 12 wherein doped semiconductor material is subsequently epitaxially grown over said additional epitaxial materials.
Claim 16
Dependent Claim
54 words
The method of claim 11 wherein regions which will ultimately form devices to which electric fields will be applied are masked prior to growth of said additional epitaxial materials so as to avoid growth of said additional epitaxial materials over said regions which will utlimately form devices to which electric fields will be applied.
Claim 17
Dependent Claim
41 words
The method of claim 14 wherein said mask is removed and doped semiconductor material is subsequently epitaxially grown over said unmasked regions to provide electrical contact to said regions which will utlimately form devices to which electric fields will be applied.
References Cited (Backward Citations)
No citation records indexed.
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