Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Forming nonplanar surface
Reexamination Certificate
1999-07-13
2003-09-09
Baxter, Janet (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Forming nonplanar surface
C430S311000, C430S312000, C430S313000, C430S314000, C430S316000, C430S324000
Reexamination Certificate
active
06617098
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to micro-machined three dimensional structures, and in particular to micro-machined movable structures.
Conventional bar code scanners are used to scan a surface with a laser beam. Conventional bar code scanners further typically utilize mirrors that are oscillated to permit the laser beam to scan. Conventional mirrors for bar code scanners are relatively large and imprecise.
In order to manufacture smaller and more precise bar code mirrors, micromachining processes are commonly used in which a silicon substrate is micromachined to produce a mirror. However, conventional micromachining processes suffer from a number of limitations.
For example, in micromachining an initially planar substrate using repeated iterations of photolithographic patterning and etching, it is typically desirable to etch the substrate to achieve etch depth variations that are greater than those appropriate for conventional photolithographic patterning methods used in manufacturing integrated circuits. In some cases, the etch depth variation of the substrate may exceed the depth of focus of the optical lithography equipment. The variation in etch depth may also be sufficiently large to preclude the application of a thin, uniform layer of photoresist using the conventional technique of pouring photoresist onto the substrate and then rapidly spinning the substrate to distribute the photoresist. If photoresist is spun onto a surface having significant topography, then the resulting thickness of the photoresist may vary by more than 1000%. As a result, lithography of fine features in uneven photoresist is difficult because of the overexposure of the thinner photoresist regions. However, in typical micromachining applications, it is typically desirable to subsequently pattern such a substrate having significant topography.
An additional complication arises during micromachining if relatively deep recesses are formed on one side of a substrate and then the other side of the substrate is micromachined. Typical vacuum chucks of conventional automatic wafer handling equipment may not be able to hold such wafers due to the uneven micromachined surface.
In order to overcome some of the difficulties of micromachining, a number of so-called merged-mask micromachining processes have been developed. The typical processing steps in a merged-mask micromachining process include forming all of the etching masks onto the substrate, and then micromachining the substrate. In this manner, the etching masks are formed on a substantially planar surface resulting in relatively consistent and even film thicknesses. However, the conventional merged-mask micromachining processes still suffer from a number of limitations.
The present invention is directed to overcoming one or more of the limitations of the existing micromachining processes.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, a method of fabricating a three-dimensional structure is provided that includes (1) providing a substrate; (2) applying a layer of a first masking material onto the substrate; (3) patterning the layer of the first masking material; (4) applying a layer of a second masking material onto the exposed portions of the substrate, the layer of the second masking material is at least as thick as the layer of the first masking material; (5) patterning the layer of the second masking material; (6) etching the exposed portions of the substrate; (7) etching the exposed portions of the layer of the second masking material; and (8) etching the exposed portions of the substrate.
According to another aspect of the present invention, a method of fabricating a three-dimensional structure is provided that includes providing a substrate; applying a layer of a first masking material onto the substrate; patterning the layer of the first masking material; applying a layer of a second masking material onto the exposed portions of the substrate, the layer of the second masking material is at least as thick as the layer of the first masking material; patterning the layer of the second masking material; etching the exposed portions of the substrate; etching the exposed portions of the layer of the second masking material; and etching the exposed portions of the substrate.
According to another aspect of the present invention, a method of fabricating a three-dimensional structure is provided that includes providing a substrate; applying a layer of a first masking material onto the substrate; patterning the layer of the first masking material; thin etching the exposed portions of the substrate; applying a layer of a second masking material onto the exposed portions of the substrate, the layer of the second masking material is at least as thick as the layer of the first masking material; patterning the layer of the second masking material; etching the exposed portions of the substrate; etching the exposed portions of the layer of the second masking material; and etching the exposed portions of the substrate.
According to another aspect of the present invention, a method of fabricating a three-dimensional structure is provided that includes providing a substrate; applying a layer of a first masking material onto the substrate; applying a layer of a second masking material onto the layer of the first masking material; patterning the layer of the second masking material; applying a layer of a third masking material onto the portions not covered by the patterned layer of the second masking material, the layer of the third masking material is at least as thick as the combined thickness of the layers of the first and second masking materials; patterning the layers of the first and third masking materials; etching the exposed portions of the substrate; etching the exposed portions of the layers of the first and third masking materials; and etching the exposed portions of the substrate.
According to another aspect of the present invention, a method of fabricating a three-dimensional structure is provided that includes providing a substrate; applying a layer of a first masking material onto the substrate; applying a layer of a second masking material onto the layer of the first masking material; patterning the layer of the second masking material; patterning the layer of the first masking material; applying a layer of a third masking material onto the portions not covered by the patterned layer of the second masking material, the layer of the third masking material is at least as thick as the combined thickness of the layers of the first and second masking materials; patterning the layers of the first and third masking materials; etching the exposed portions of the substrate; etching the exposed portions of the layers of the first and third masking materials; and etching the exposed portions of the substrate.
According to another aspect of the present invention, a method of fabricating a three-dimensional structure is provided that includes providing a substrate; applying a layer of a first masking material onto the substrate; applying a layer of a second masking material onto the layer of the first masking material; patterning the layer of the second masking material; patterning the layer of the first masking material; thin etching the exposed portions of the substrate; applying a layer of a third masking material onto the portions not covered by the patterned layer of the second masking material, the layer of the third masking material is at least as thick as the combined thickness of the layers of the first and second masking materials; patterning the layers of the first and third masking materials; etching the exposed portions of the substrate; etching the exposed portions of the layers of the first and third masking materials; and etching the exposed portions of the substrate.
According to another aspect of the present invention, a method of fabricating a three-dimensional structure is provided that includes providing a substrate; applying a layer of a first masking material onto the substrate; pa
Goldberg Howard D.
Ried Robert P.
Yu Duli
Yu Lianzhong
Baxter Janet
Input / Output Inc.
Madan Mossman & Sriram P.C.
Walke Amanda C.
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