METHOD OF COMPENSATION FOR BLEACHING OF RESIST DURING THREE-DIMENSIONAL EXPOSURE OF RESIST
First Claim
1. A method of forming a three-dimensional latent image with good depth and shape control in a resist layer applied over a workpiece surface, the method including:
- using in the resist layer a positive resist with an effective absorption characteristic that produces a log-linear relationship between exposure energy (E) and the depth of exposure (D), approximated to a first order by D=c1 ln(E)+c2, rather than a linear relationship;
converting a relief map that represents a three-dimensional surface into point-by-point exposure doses calculated to reach an exposure threshold of the positive resist at a plurality of controlled depths within the resist layer, taking into account the log-linear relationship, producing an exposure map; and
patterning the resist layer to form a three-dimensional latent image using a pattern generator that varies effective exposure doses on a point-by-point basis using the exposure map.
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Accused Products
Abstract
The field of this disclosure is making three-dimensional topographic structures by means of graduated exposure in a photosensitive material, such as a photoresist, photosensitive polymide, or similar. Such patterns may be written either to be used directly as optical, mechanical, fluidic, etc. components, e.g. diffusors, non-reflecting surfaces, Fresnel lenses and Fresnel prisms, computer-generated holograms, lenslet arrays, etc, or to be used as masters for the fabrication of such components by replication. Replication can be done by molding, pressing, embossing, electroplating, etching, as known in the art. This disclosure includes descriptions of using passive absorbing components in thin resist, using high gamma thick resists with high resolution pattern generators, using multiple focal planes including at least one focal plane in the bottom half of the resist, and iterative simulation of patterning and adjustment of an exposure map.
18 Citations
20 Claims
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1. A method of forming a three-dimensional latent image with good depth and shape control in a resist layer applied over a workpiece surface, the method including:
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using in the resist layer a positive resist with an effective absorption characteristic that produces a log-linear relationship between exposure energy (E) and the depth of exposure (D), approximated to a first order by D=c1 ln(E)+c2, rather than a linear relationship; converting a relief map that represents a three-dimensional surface into point-by-point exposure doses calculated to reach an exposure threshold of the positive resist at a plurality of controlled depths within the resist layer, taking into account the log-linear relationship, producing an exposure map; and patterning the resist layer to form a three-dimensional latent image using a pattern generator that varies effective exposure doses on a point-by-point basis using the exposure map. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification