US 5,632,908 A · Method for making aligned features

Abstract

An optical fiber support member is made by forming on a monocrystalline silicon substrate member (26) a first mask layer (27) of, e.g., silicon dioxide. The first mask layer is masked and etched to a first depth to define a pattern of first (29) and second (30) features, the first features defining the locations of optical fiber support grooves (15), and the second features defining the locations of support member reference surfaces (17, 19). Next, only the second features are etched to a second depth deeper than the first depth. Finally, the first and second features are simultaneously etched into the substrate such that the second features are etched to a greater depth than the first features. By defining the first and second features simultaneously in a single mask and etch step, one can assure the final precise alignment of etched V-grooves to etched reference surfaces. The second masking and etching step is used only to increase the depth of the second features defining the reference surfaces, not to determine their alignments. Consequently, if this second masking step is slightly misaligned, it will not necessarily result in a misalignment of the V-grooves with respect to the reference surfaces.

Claims21

Dependent claims

A method for making an optical fiber support member comprising the steps of:

forming on a substrate member a first mask layer;
simultaneously masking and etching to a first depth in the first mask layer a pattern of first and second features, the first features defining locations of optical fiber support grooves, and the second features defining the locations of support member reference surfaces;
masking and etching only the second features to a second depth deeper than the first depth;
and simultaneously etching into said substrate the first and second features such that the second features are etched to a greater depth than the first features.

1 more element

A method for etching in a substrate first and second grooves having a predetermined registration, the second groove being deeper than the first groove, comprising the steps of:

forming on the substrate a first mask layer;
forming over the first mask layer a second mask layer;
using a first photomask having openings defining the relative locations of both the first and second grooves to define first and second openings in the second mask layer, the first and second openings corresponding to the locations of the first and second grooves respectively;
etching the portions of the first mask layer exposed by the first and second openings to a first depth that is smaller than the thickness of the first mask layer;
removing the second mask layer;
applying to the first mask layer a third mask layer;
using a second photomask having an opening defining the location of only the second groove to define a third opening in the third mask layer, the third opening corresponding to the location of the second groove but having a wider width than that of the second opening;
etching the portion of the first mask layer exposed by the third opening such that part of the first mask layer is etched to a second depth that is equal to the thickness of the first mask layer, thereby to form a fourth opening in the first mask layer which exposes the substrate, the fourth opening having a width substantially equal to the width of the second opening in the second mask layer;
etching the portion of the substrate exposed by the fourth opening to form part of the second groove;
etching the first mask layer to produce therein a fifth opening having a width corresponding to that of the first opening in the second mask layer;
and etching the portions of the substrate exposed by the fourth and fifth openings to form second and first grooves, respectively, the second groove having a greater depth than the first groove.

8 more elements

A method for making first and second grooves in a support member comprising the steps of:

forming on a substrate member a first mask layer;
simultaneously masking and etching to a first depth in the first mask layer first and second trenches, the first trench defining the location of a first groove, and the second trench defining the location of a second groove;
masking and etching the second trench to a second depth deeper than the first depth without etching the first trench;
and simultaneously etching into said substrate the first and second grooves such that the second groove is etched to a greater depth than the first groove.

1 more element

Dependencies are inferred from the claim text.

Method for making aligned features

Life of this patent

Method for making aligned features

Life of this patent

Abstract

Claims21