Etching process for micromachining crystalline materials and devices fabricated thereby
View Patent ↗The present invention relates generally to micromachining. More particularly, the present invention relates to a method for combining directional ion etching and anisotropic wet etching and devices and structures fabricated thereby. The present invention is particularly applicable to silicon micromachining and provides architectures that combine crystallographic surfaces and vertical dry etched surfaces together in the same structure.
1. A method for micromachining a crystalline substrate, comprising:
providing a crystalline substrate;
directionally etching a first etch-stop pit in the substrate;
coating the first etch-stop pit with a mask material;
anisotropically wet etching an area adjacent to the first etch-stop pit to provide a groove for holding an optical element, wherein the groove is disposed in the substrate;
anisotropically wet etching a first wet-etched pit afier formation of the first etch-stop pit, the first wet-etched pit comprising a sidewall to provide a reflection surface for optical communication with an optical element held in the groove,
wherein the first etch-stop pit is disposed between the groove and the first wet-etched pit.
2. The method according to claim 1 , comprising:
directionally etching a second etch-stop pit in the substrate;
coating the second etch-stop pit with a mask material;
anisotropically wet etching an area between the first and second etch-stop pits to provide a second wet-etched pit between the first and second etch-stop pits.
3. The method according to claim 1 , wherein the first etch-stop pit comprises a first sidewall portion that intersects the groove at a non-orthogonal angle relative to a longitudinal axis of the groove so that formation of at least a portion of a wedge-shaped end portion of the groove is prevented and comprises a second sidewall portion that intersects the first wet-etched pit so that formation of at least a portion of a sidewall of the first wet-etched pit adjacent the etch-stop pit is prevented.
4. The method according to claim 1 , wherein the substrate comprises single crystal silicon.
5. The method according to claim 1 , wherein the first etch-stop pit comprises a vertical sidewall to provide a fiber stop.
6. The method according to claim 1 , wherein the first wet-etched pit comprises an elongated pit and comprises a second sidewall portion that intersects the elongated pit at a non-orthogonal angle relative to a longitudinal axis of the elongated pit.
7. The method according to claim 1 , wherein the reflection surface is a crystallographic plane of the substrate.
8. The method according to claim 1 , comprising providing an optical fiber disposed in the groove.