Photomask

About: Photomask is a research topic. Over the lifetime, 7917 publications have been published within this topic receiving 54524 citations. The topic is also known as: photoreticle & reticle.

Reticle inspection system

Abstract: An automatic inspection system including an illuminator for illuminating a reticle or photomask to be inspected, while optically projecting a magnified image of the reticle or photomask onto a plurality of detector elements. A carriage assembly moves the object at a constant velocity to allow the detector elements to sequentially view the entire surface to be inspected. The detector elements are responsive to the intensity of light incident thereupon and are periodically scanned to obtain a two-dimensional measured representation of the object. A database adaptor formulates a two-dimensional representation from the design database description corresponding to the scanned object simultaneously and in synchronism with the scanning of the photomask or reticle. The measured and database adapted representation of the scanned object are input to a signal processor for alignment and defect detection. While the representations are shifted through a memory, an alignment circuit dynamically measures and corrects for misalignment between the representations, so that a defect detector can effectively compare the representations for defects. Additional correction of misalignment between the representations is obtained by modulating the size of the measured representation as detected by the detector elements. At the operator's option, a second measured image of a multi-cell reticle or photomask may be used for comparison as a substitute for the database representation.

Optical proximity correction common process window maximization over varying feature pitch

Abstract: Maximizing a common process window for optical proximity correction (OPC)-modified features of a semiconductor design having varying pitch is disclosed. For each pitch within a semiconductor design, a bias needed at the pitch that maximizes a common process window for the number of pitches given a critical dimension (CD) specification for a semiconductor design of the photomask is determined. The original layout for the semiconductor design of the photomask is then modified by performing rule-based optical-proximity correction (OPC), including adding the bias determined at each pitch, to yield a modified layout for the semiconductor design of the photomask. The modified layout is further modified by performing model-based on the modified layout such that exposed semiconductor wafer CD's at each pitch are at least substantially equal to the CD specification for the pitch, to yield a final layout for the semiconductor design of the photomask.

Method and apparatus of model-based photomask synthesis

Abstract: An apparatus and method for improving image quality in a photolithographic process includes calculating a figure-of-demerit for a photolithographic mask function and then adjusting said photolithographic mask function to reduce the figure of demerit.

Lithographic image size reduction

Abstract: Disclosed is a process for reducing lithographic image size for integrated circuit manufacture. A mask (14) of photosensitive material having an opening (20) of a minimum size (A) dictated by the limits of lithography is formed on a substrate (10). Reduction in the image size is achieved by establishing sidewalls (24) to the interior vertical surfaces of the opening by depositing a conformal layer (22), followed by anisotropic etching. The dimension (C) of the new opening is reduced by the combined thickness of the two opposite insulator sidewalls. In a specific direct application of the disclosed process, a photomask/stencil having a pattern of openings of a minimum size smaller than possible by lithography, per se, is formed.

Polymeric optical waveguides using direct ultraviolet photolithography process

Abstract: Single-mode polymeric channel waveguides were fabricated using simple direct ultraviolet photolithography process. A cross-linkable negative tone epoxy NANOTM SU-8 2000 polymer was used. Once exposed to ultraviolet light through a photomask, the waveguide stripes were obtained upon development. The polymer has many desirable properties, such as high refractive index, good adhesion to substrate, optical transparency in the infrared wavelength region, and high glass transition and high thermal decomposition temperatures. Properties of the optical waveguides were characterized, and there is an excellent agreement between measured data and theory. The values of dn/dT and waveguide birefringence are -1.87×10-4 /°C and ∼10-4, respectively, and are comparable to those of halogenated acrylate polymers. With an overcladding layer, the propagation losses measured are 0.25 and 0.28 dB/cm at 0.8 μm, 0.62 and 0.77 dB/cm at 1.31 μm, and 1.25 and 1.71 dB/cm at 1.55 μm for TE and TM polarizations, respectively.