Etching a substrate: processes – Forming or treating optical article
Patent
1996-04-01
1997-12-23
Powell, William
Etching a substrate: processes
Forming or treating optical article
1566331, 1566451, 15665711, 216 2, 216 33, 216 41, 216 52, H01L 2100, B44C 122
Patent
active
057003823
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a method for fabricating a silicon semiconductor substrate having an integrated waveguide and an optical fiber coupled thereto, in the case of which the integrated waveguide is provided with a freely accessible end surface by producing a recess in the silicon semiconductor substrate, the end surface at the recess is situated opposite the end of a V-shaped groove etched anisotropically in the silicon semiconductor substrate, and the optical fiber is inserted into the groove, extending up to the freely accessible end surface of the integrated waveguide.
It is known from an essay by M. F. Grant, S.Day and R. Bellerby, "Low-loss coupling of ribbon fibres to silica-on-silicon integrated optics using preferentially etched V-grooves" in "Integrated Photonics Research", (Summaries of papers presented at the Integrated Photonics Research Topical Meeting, Apr. 13-16, 1992, New Orleans--Technical Digest Series, vol. 10, pp. 166-167) to produce a semiconductor substrate with an integrated waveguide and an optical fiber coupled thereto by first introducing a V-shaped groove into the semiconductor substrate through anisotropic etching. Waveguide layers are then applied to the semiconductor substrate. A duct-type waveguide is subsequently formed through a reactive ion etching. The semiconductor substrate prepared thus far is subsequently provided with a groove by means of sawing in the manner that a perpendicularly running end surface of the integrated waveguide is produced so as to be freely accessible. After that, the optical fiber is inserted into the V-shaped groove so as to extend up to the freely accessible end surface of the integrated waveguide. In this manner, one obtains a silicon semiconductor substrate with an integrated waveguide and an optical fiber coupled thereto, where the optical fiber is aligned to the freely accessible end surface of the integrated waveguide, provided that the saw cut is executed with a comparable exact alignment.
The object of the invention is to propose a method for fabricating a silicon semiconductor substrate with an integrated semiconductor and an optical fiber coupled thereto, which will make it possible to produce a silicon semiconductor substrate that is distinguished by a very high optical quality of the coupling site, cost-effectively, and with a very precise alignment of the optical fibers to the freely accessible end surface of the integrated waveguide.
As a means for achieving this objective as in a method of the type indicated at the outset, the invention proposes forming the recess in the silicon semiconductor substrate by separating out a piece of the silicon semiconductor substrate by baring the piece to be cut right down to a region surrounding the integrated waveguide by means of anisotropic etching from the surface of the silicon semiconductor substrate opposite the surface bearing the groove, the region surrounding the integrated waveguide being weakened by the etching of a V-shaped notch; pressure is exerted on the piece to be separated out, causing it to subsequently break off at the V-shaped notch, while the freely accessible end surface of the integrated waveguide is formed as a fracture surface.
It is, in fact, disclosed by the German Provisional Patent 41 42 850 A1 in a semiconductor substrate having an integrated waveguide in the region of the coupling site to provide a recess in the form of an etch pit between the waveguide and the optical fiber by means of depth etching, however, the semiconductor substrate is made of a III-V semiconductor material, and the semiconductor substrate is composed of a plurality of layers comprising, inter alia, an etch layer that enables a selective wet etching. This etch layer is laid bare by the etch pit, so that a portion of the etch layer can be dissolved out by means of selective wet etching in the vicinity of the etch pit. The portion of the etch layer that is tab are thus laid bare, so that the tab can be broken off by means of ultrasound while forming a low-loss, optical butting coupling.
The
REFERENCES:
patent: 5017263 (1991-05-01), Clark
patent: 5466558 (1995-11-01), Sasaki
Grant, et al. "Low-loss Coupling of Ribbon Fibres to Silica-on Silicon Integrated Optics Using Preferentially Etched V-grooves", Integrated Photonics Research, 1991, pp. 166-167.
Powell William
Siemens Aktiengesellschaft
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