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1082 results about "Optical proximity correction" patented technology

Optical proximity correction (OPC) is a photolithography enhancement technique commonly used to compensate for image errors due to diffraction or process effects. The need for OPC is seen mainly in the making of semiconductor devices and is due to the limitations of light to maintain the edge placement integrity of the original design, after processing, into the etched image on the silicon wafer. These projected images appear with irregularities such as line widths that are narrower or wider than designed, these are amenable to compensation by changing the pattern on the photomask used for imaging. Other distortions such as rounded corners are driven by the resolution of the optical imaging tool and are harder to compensate for. Such distortions, if not corrected for, may significantly alter the electrical properties of what was being fabricated. Optical proximity correction corrects these errors by moving edges or adding extra polygons to the pattern written on the photomask. This may be driven by pre-computed look-up tables based on width and spacing between features (known as rule based OPC) or by using compact models to dynamically simulate the final pattern and thereby drive the movement of edges, typically broken into sections, to find the best solution, (this is known as model based OPC). The objective is to reproduce on the semiconductor wafer, as well as possible, the original layout drawn by the designer.

Data hierarchy layout correction and verification method and apparatus

A method and apparatus for the correction of integrated circuit layouts for optical proximity effects which maintains the original true hierarchy of the original layout is provided. Also provided is a method and apparatus for the design rule checking of layouts which have been corrected for optical proximity effects. The OPC correction method comprises providing a hierarchically described integrated circuit layout as a first input, and a particular set of OPC correction criteria as a second input. The integrated circuit layout is then analyzed to identify features of the layout which meet the provided OPC correction criteria. After the areas on the mask which need correction have been identified, optical proximity correction data is generated in response to the particular set of correction criteria. Finally, a first program data is generated which stores the generated optical proximity correction data in a hierarchical structure that corresponds to the hierarchical structure of the integrated circuit layout. As the output correction data is maintained in true hierarchical format, layouts which are OPC corrected according to this method are able to be processed through conventional design rule checkers with no altering of the data.
Owner:SYNOPSYS INC

Method to determine optical proximity correction and assist feature rules which account for variations in mask dimensions

Optical proximity correction (OPC) and assist feature rules are generated using a process window (PW) analysis. A reference pitch is chosen and the mask bias is found that optimizes the process window. This can be done using standard process window analysis or through a weighted process window (WPW) analysis which accounts for focus and dose distributions that are expected in a real process. The WPW analysis gives not only the optimum mask bias, but also the center focus and dose conditions for the optimum process centering. A series of other pitches and mask biases are then analyzed by finding the common process window with the reference pitch. For the standard PW analysis, a common process window is found. For the WPW analysis, the WPW is computed at the center focus and dose conditions found for the reference pitch. If mask or lens errors are to be accounted for, then multiple structures can be included in the analysis. Once the common process windows for the mask features of interest have been computed, functional fits to the data can be found. Once the functional forms have been found for each of the OPC parameters, the rules table can be determined by solving for the spacings of interest in the design.
Owner:GLOBALFOUNDRIES U S INC

Method and system for managing design corrections for optical and process effects based on feature tolerances

A method for modifying instances of a repeating pattern in an integrated circuit design to correct for perturbations during rendering is described. In the typical embodiment, these corrections are optical proximity corrections that correct for optical effects during the projection of the mask pattern onto the wafer and / or processing effects for example photoresist response and etching effects. The method comprises determining a correction for the repeating pattern based on a first set of tolerances for features of the repeating pattern. Then, the suitability of the corrections is evaluated for instances of the repeating pattern in the integrated circuit design based on a second set of tolerances, which is different from the first set of tolerances. This can be used to preserve much of the hierarchy of the layout data in the corrected, or lithography, data. This can be achieved during the OPC process, thus avoiding the post OPC compaction. It can further take advantage of the fact that, for a given physical layer of a chip for example, different portions of the representing design polygons typically have different requirements on pattern fidelity on the wafer while perturbations may vary as a function of field position. By applying knowledge of the feature tolerances, and allowing design corrections only when tolerances are not met, the data explosion that occurs when moving from layout to lithography data can be contained without sacrificing accuracy.
Owner:CADENCE DESIGN SYST INC

System and method for analysis and transformation of layouts using situations

Systems, methodologies and technologies for the analysis and transformation of integrated circuit layouts using situations are disclosed. A method for transforming an integrated circuit (IC) layout includes recognizing shapes within the IC layout, identifying features for each of the shapes and extracting situations for the respective features. Extracted situations can be used to improve optical proximity correction (OPC) of the IC layout. This improved OPC includes extracting the situations, simulating the situations to determine a set of the situations identified for modification based on failing to satisfy a desired OPC tolerance level, modifying the set of situations to improve satisfaction of the desired OPC tolerance level, and reintegrating the modified set of situations into the IC layout. Extracted situations can also be used to improve aerial image simulation of the IC layout. This improved aerial image simulation includes extracting the situations, simulating a subset of the situations to determine aerial images of the subset, and tiling the subset of situations to form a larger aerial image. Extracted situations can further be used to improve density analysis of the IC layout. This improved density analysis includes extracting the situations for a window of the IC layout, removing overlap from the window based on the extracted situations, calculating a density for each of the situations, and calculating a density for the window based on the density for each of the situations.
Owner:CADENCE DESIGN SYST INC
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