摘要:
A method is provided for designing a mask that includes the use of a pixel-based simulation of a lithographic process model, in which test structures are designed for determining numerical and discretization errors associated with the pixel grid as opposed to other model inaccuracies. The test structure has a plurality of rows of the same sequence of features, but each row is offset from other rows along an x-direction by a multiple of a minimum step size, such as used in modifying masks during optical proximity correction. The images for each row are simulated with a lithographic model that uses the selected pixel-grid size and the differences between row images are compared. If the differences between rows exceed or violate a predetermined criterion, the pixel grid size may be modified to minimize discretization and/or numerical errors due to the choice of pixel grid size.
摘要:
A method, system and computer program product for rendering a mask are disclosed. A method of rendering a mask may comprise: providing an initial mask design for a photolithographic process, the initial mask design including polygons; initially rendering the initial mask design as a coarse mask representation in a pixel based image calculation; identifying an overhang portion; and rendering the overhang portion using a set of subpixels whose artifacts from spatial-localization lie outside a practical resolution of a pseudo lens having a numerical aperture larger than that of a projection lens used in the photolithographic process; and updating the initial rendering based on the overhang portion rendering.
摘要:
A method and system for exposing a resist layer with regions of photosensitivity to an image in a lithographic process using a high numerical aperture imaging tool. There is employed a substrate having thereover a layer reflective to the imaging tool radiation and a resist layer having a region of photosensitivity over the reflective layer, with the resist layer having a thickness. The imaging tool is adapted to project radiation containing an aerial image onto the resist layer, with a portion of the radiation containing the aerial image passing through the resist layer and reflecting back to the resist layer. The reflected radiation forms an interference pattern in the resist layer of the projected aerial image through the resist layer thickness. The thickness and location of the resist layer region of photosensitivity with respect to the reflective layer are selected to include from within the interference pattern higher contrast portions of the interference pattern in the direction of the resist thickness, and to exclude lower contrast portions of the interference pattern in the resist thickness direction from said resist layer region of photosensitivity, to improve contrast of the aerial image in said resist layer region of photosensitivity.
摘要:
A set of candidate global optima is identified, one of which is a global solution for making a mask for printing a lithographic pattern. A solution space is formed from dominant joint eigenvectors that is constrained for bright and dark areas of the printed pattern. The solution space is mapped to identify regions each containing at most one local minimum intensity. For each selected region, stepped intensity contours are generated for intensity of the dark areas and stepped constraint surfaces are generated for a target exposure dose at an individual test point. An individual test point is stepped toward a lowest intensity contour along the stepped constraint surfaces of each selected region. Further lowering of the intensities of these points is also detailed, where possible in adjacent regions, to yield final test points. The set of candidate global optima is the final test points at their respective lowest intensity contour of the respective selected regions.
摘要:
Methods, and program storage devices, for performing model-based optical proximity correction by providing a region of interest (ROI) having an interaction distance and locating at least one polygon within the ROI. A cut line of sample points representative of a set of vertices, or plurality of cut lines, are generated within the ROI across at least one lateral edge of the polygon(s). An angular position, and first and second portions of the cut line residing on opposing sides of an intersection between the cut line and the lateral edge of the polygon are determined, followed by generating a new ROI by extending the original ROI beyond its interaction distance based on such angular position, and first and second portions of the cut line. In this manner, a variety of new ROIs may be generated, in a variety of different directions, to ultimately correct for optical proximity.
摘要:
A method, program product and system is disclosed for performing optical proximity correction (OPC) wherein mask shapes are fragmented based on the effective image processing influence of neighboring shapes on the shape to be fragmented. Neighboring shapes are smoothed prior to determining their influence on the fragmentation of the shape of interest, where the amount of smoothing of a neighboring shape increases as the influence of the neighboring shape on the image process of the shape of interest decreases. A preferred embodiment includes the use of multiple regions of interactions (ROIs) around the shape of interest, and assigning a smoothing parameter to a given ROI that increases as the influence of shapes in that ROI decreases with respect to the shape to be fragmented. The invention provides for accurate OPC that is also efficient.
摘要:
Methods, and a program storage device for executing such methods, for performing model-based optical proximity correction by providing a mask matrix having a region of interest (ROI) and locating a plurality of points of interest within the mask matrix. A first polygon having a number of vertices representative of the located points of interest is computed, followed by determining a spatial relation between its vertices and the ROI. The vertices of the first polygon are then pinned to boundaries of and within the ROI such that a second polygon is formed on the ROI. The process is repeated for all vertices of the first polygon such that the second polygon is collapsed onto the ROI. This collapsed second polygon is then used to correct for optical proximity.
摘要:
A method and system is provided for computing lithographic images that may take into account non-scalar effects such as lens birefringence, resist stack effects, tailored source polarizations, and blur effects of the mask and the resist. A generalized bilinear kernel is formed, which is independent of the mask transmission function, and which may then be treated using a decomposition to allow rapid computation of an image that includes such non-scalar effects. Weighted pre-images may be formed from a coherent sum of pre-computed convolutions of the dominant eigenfunctions of the generalized bilinear kernel with the appropriate mask polygon sectors. The image at a point may be formed from the incoherent sum of the weighted pre-images over all of the dominant eigenfunctions of the generalized bilinear kernel. The resulting image can then be used to perform model-based optical proximity correction (MBOPC).
摘要:
Methods, and program storage devices, for performing model-based optical lithography corrections by partitioning a cell array layout, having a plurality of polygons thereon, into a plurality of cells covering the layout. This layout is representative of a desired design data hierarchy. A density map is then generated corresponding to interactions between the polygons and plurality of cells, and then the densities within each cell are convolved. An interaction map is formed using the convolved densities, followed by truncating the interaction map to form a map of truncated cells. Substantially identical groupings of the truncated cells are then segregated respectively into differing ones of a plurality of buckets, whereby each of these buckets comprise a single set of identical groupings of truncated cells. A hierarchal arrangement is generated using these buckets, and the desired design data hierarchy enforced using the hierarchal arrangement to ultimately correct for optical lithography.
摘要:
A liquid crystal (LC) lightvalve comprising a twisted nematic LC layer whose molecules are aligned with pixel edges at the mirror backplane, thereby providing improved contrast and efficiency, and reduced visibility of post spacers in black state. The present invention is directed to an LC structure wherein the backplane is rubbed in a direction rectilinear with pixel edges. The LC layer is given the same twist rotation and birefringence as in the conventional TN lightvalve. Polarization control is maintained by illuminating the lightvalve with light whose polarization is rotated by the twist angle relative to the x,y, pixel axes, and by collecting the orthogonally polarized component of the reflected light. The lightvalve top glass is thus rubbed in a direction which is rotated by the twist angle from the horizontal or vertical direction at which the backplane is rubbed.