# Patent

## Title
Methods and systems for process compensation technique acceleration

## Abstract

Selected cells in a semiconductor chip layout are replaced with corresponding PCT pre-processed cells. Each PCT pre-processed cell represents a particular selected cell having been previously subjected to a cell-level-PCT-processing operation so as to include PCT-based cell layout adjustments. Following replacement of the selected cells in the semiconductor chip layout with corresponding PCT pre-processed cells, a chip-wide PCT processing operation is performed on the semiconductor chip layout for a given chip level. The presence of the PCT pre-processed cells in the semiconductor chip layout serves to accelerate the chip-wide PCT processing of the semiconductor chip layout. The chip-wide PCT processed semiconductor layout for the given chip level is recorded on a persistent storage medium.

## Background
CLAIM OF PRIORITY
This application is a continuation-in-part application under 35 U.S.C. 120 of prior U.S. application Ser. No. 12/033,807, filed on Feb. 19, 2008 now U.S. Pat. No. 7,979,829, entitled “Integrated Circuit Cell Library with Cell-Level Process Compensation Technique (PCT) Application and Associated Methods,” which claims priority under 35 U.S.C. 119(e) to U.S. Provisional Application No. 60/890,819, filed on Feb. 20, 2007. The disclosure of each above-identified patent application is incorporated herein by reference.
This application also claims priority under 35 U.S.C. 119(e) to U.S. Provisional Patent Application No. 61/087,546, filed Aug. 8, 2008, entitled “Methods and Systems for Process Compensation Technique Acceleration.” The disclosure of the above-identified provisional patent application is incorporated herein by reference.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is also related to U.S. patent application Ser. No. 11/683,402, filed on Mar. 7, 2007, and entitled “Dynamic Array Architecture.” This application is also related to U.S. patent application Ser. No. 12/013,342, filed on Jan. 11, 2008, and entitled “Semiconductor Device with Dynamic Array Section.” This application is also related to U.S. patent application Ser. No. 12/013,356, filed on Jan. 11, 2008, and entitled “Methods for Designing Semiconductor Device with Dynamic Array Section.” This application is also related to U.S. patent application Ser. No. 12/013,366, filed on Jan. 11, 2008, and entitled “Methods for Defining Dynamic Array Section with Manufacturing Assurance Halo and Apparatus Implementing the Same.” The disclosures of the above-identified patent applications are incorporated herein by reference.


BACKGROUND
Current integrated circuit (IC) design flows are broken into several functions. Design teams typically focus on synthesis, place and route, layout versus schematic (LVS), timing closure, power closure, reliability closure, and design rule checking (DRC). The “GDS-II” database is signed off and released to a post-design processing team which applies various forms of RET (resolution enhancement techniques), mainly OPC (optical proximity correction). OPC is done on pre-defined masking layers, usually using lithographic models provided by the wafer fabrication facility (fab). Each mask layer of the whole chip is run through OPC with the appropriate model, then released to the mask shop for fracturing and mask making.
In today's era of sub-wavelength photolithography, in which the feature sizes are smaller than the wavelength of the exposure light, the full-chip OPC creates patterns for the masks which are difficult to validate for correctness. A number of electronic design automation (EDA) tools are trying to perform “hot spot” checks or design rule checking (DRC) on the full-chip post-OPC databases. Sheer data volumes make this difficult, as the post-OPC databases can be 20 to 100 times larger than the original layout. Therefore, full-chip OPC can be extremely expensive in terms of cost and schedule. In fact, it may take many weeks of processor time to complete a full-chip OPC on a single chip level. Also, OPC done on the full chip at this phase of the design flow is in the critical path for getting the database to the mask shop. Moreover, after the full-chip OPC processing, the chip layout may go through another process called mask proximity correction (MPC) to adjust layout shapes to get better pattern fidelity on the mask, which will add additional delay in releasing the chip layout to the mask shop.
SUMMARY
In one embodiment, a method is disclosed for accelerating process compensation technique (PCT) processing of a semiconductor chip layout. The method includes an operation for replacing selected cells in the semiconductor chip layout with corresponding PCT pre-processed cells. Each PCT pre-processed cell represents a particular selected cell having been previously subjected to a cell-level-PCT-processing operation so as to include PCT-based cell layout adjustments. Following replacement of the selected cells in the semiconductor chip layout with corresponding PCT pre-processed cells, the method includes an operation for performing a chip-wide PCT processing operation on the semiconductor chip layout for a given chip level. The method further includes an operation for recording the chip-wide PCT processed semiconductor layout for the given chip level on a persistent storage medium.
In another embodiment, a method in disclosed for processing a semiconductor chip layout for fabrication. The method includes an operation for obtaining a chip layout having a number of cells placed in a section of the chip layout to form a prescribed integrated circuit. The method also includes an operation for replacing one or more of the number of placed cells with a corresponding PCT pre-processed cell. A given PCT pre-processed cell represents a particular placed cell having been previously subjected to a cell-level-PCT-processing operation so as to include PCT-based cell layout adjustments within the given PCT pre-processed cell. The method further includes an operation for performing a chip-wide PCT processing operation on a given level of the chip layout to generate a chip-wide PCT processed chip layout for the given level of the chip layout. An operation is then performed to record the chip-wide PCT processed chip layout for the given level on a persistent storage medium. The method operations of performing the chip-wide PCT processing operation and recording the chip-wide PCT processed chip layout is repeated for each level of the chip that requires PCT processing for fabrication.
In another embodiment, a PCT processing system is disclosed. The system includes an input module defined to receive a chip layout for PCT processing. The chip layout includes a number of cells placed in a section of the chip layout to form a prescribed integrated circuit. The system also includes a cell substitution module defined to replace one or more of the number of cells in the chip layout with a corresponding PCT pre-processed cell. A given PCT pre-processed cell represents a particular cell having been previously subjected to a cell-level-PCT-processing operation so as to include PCT-based cell layout adjustments within the given PCT pre-processed cell. The system further includes a PCT processing module defined to perform a chip-wide PCT processing operation on specified levels of the chip layout to generate a chip-wide PCT processed chip layout for each of the specified levels of the chip layout. The system also includes an output module defined to record the chip-wide PCT processed chip layout for each of the specified levels of the chip layout on a persistent storage medium.
Other aspects and advantages of the invention will become more apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the present invention.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an illustration showing an exemplary cell surrounded by a litho-buffer, in accordance with one embodiment of the present invention;
FIG. 2A is an illustration showing a layout of a gate level of a cell prior to cell-level-PCT processing, in accordance with one embodiment of the present invention;
FIG. 2B is an illustration showing the gate level layout of cell with cell-level-PCT processing performed thereon, in accordance with one embodiment of the present invention;
FIG. 3 is an illustration showing a flowchart of a method for generating a library of PCT processed cells for use in an integrated circuit design, in accordance with one embodiment of the present invention;
FIG. 4 is an illustration showing a flowchart of a method for accelerating PCT processing of a semiconductor chip layout, in accordance with one embodiment of the present invention;
FIG. 5A shows an exemplary chip layout for a given level of a chip, in accordance with one embodiment of the present invention;
FIG. 5B shows the exemplary chip layout of FIG. 5A with selected cells replaced with corresponding PCT pre-processed cells, in accordance with one embodiment of the present invention;
FIG. 5C shows the exemplary chip layout of FIG. 5B with identification of cells having been subjected to the chip-wide PCT processing, in accordance with one embodiment of the present invention;
FIG. 5D shows the exemplary chip layout of FIG. 5B with identification of cells having been subjected to the chip-wide PCT processing, in accordance with one embodiment of the present invention;
FIG. 5E shows the exemplary chip layout of FIG. 5A with specification of cells for PCT processing during the chip-wide PCT processing, in accordance with one embodiment of the present invention;
FIG. 5F shows the exemplary chip layout of FIG. 5E with identification of cells having been subjected to the chip-wide PCT processing, in accordance with one embodiment of the present invention;
FIG. 6 is an illustration showing a flowchart of a method for processing a semiconductor chip layout for fabrication, in accordance with one embodiment of the present invention; and
FIG. 7 is an illustration showing a PCT processing system, in accordance with one embodiment of the present invention.



DETAILED DESCRIPTION
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without some or all of these specific details. In other instances, well known process operations have not been described in detail in order not to unnecessarily obscure the present invention.
As used herein, a process compensation technique (PCT) refers to essentially any processing or adjustment of an integrated circuit (IC) layout for the purpose of improving or ensuring successful fabrication of the features defined by the IC layout. Examples of various PCTs include optical proximity correction (OPC), mask proximity correction (MPC), resolution enhancement techniques (RET), etch proximity compensation, gap fill compensation (e.g., use of dielectric or metal to fill gaps), chemical mechanical planarization (CMP) compensation, among others. It should be understood that the term PCT processing, as used herein, refers to any existing or future form of IC layout processing used to improve or ensure successful fabrication of features defined by the IC layout.
A cell represents an abstraction of a logic function or other signal processing function (analog, RF, optical) to be performed by an integrated circuit, and encapsulates the lower-level integrated circuit layout for implementing the logic function. It should be understood that a given logic function can be represented by multiple cell variations, wherein the cell variations may be differentiated by feature size, performance, and process compensation technique (PCT) processing. For example, multiple cell variations for a given logic function may be differentiated by power consumption, signal timing, current leakage, chip area, OPC, MPC, RET, etc. It should also be understood that each cell description includes the layouts for the cell in each level of the chip, as required to implement the logic function of the cell. More specifically, a cell description includes layouts for the cell in each level of the chip extending from the substrate level up through a particular interconnect level.
Cell-level-PCT-processing can be performed on a number of levels of one or more cells used in a chip-wide layout. For example, in one embodiment, cell-level-PCT-processing can be performed on selected levels of each unique cell in the chip-wide layout. However, in another embodiment, cell-level-PCT-processing can be performed on selected levels of selected cells in the chip-wide layout.
It should be appreciated that the cell-level-PCT processing is performed without explicit consideration of the chip as a whole. However, in performing the cell-level-PCT processing on a given cell, a lithographic buffer region (“litho-buffer” hereafter) is defined around each level of the cell to simulate a chip environment in which the cell may be placed. FIG. 1 is an illustration showing an exemplary cell 101 surrounded by a litho-buffer 103, in accordance with one embodiment of the present invention. Generally speaking, the litho-buffer associated with a given level of the cell is defined to include a number of features that simulate the neighborhood in which the cell will be placed on the chip. The size of the litho-buffer for a given level of the cell is defined by the outward extent of the litho-buffer from the cell. The size of the litho-buffer for a given level of the cell is set such that the litho-buffer covers an area capable of lithographically influencing the given level of the cell. For example, with regard to FIG. 1, the size of the litho-buffer 103 is defined by its outward extent from the cell 101, as indicated by arrows 105. Alternatively, a “process buffer” could be defined if the range of influence for a given process step is larger than the lithographic influence.
In one embodiment, the outward extent of the litho-buffer can vary on different sides of the cell. In another embodiment, the outward extent of the litho-buffer is the same on each side of the cell. In one embodiment, the litho-buffer for a given level of the cell is defined to extend about 1 micrometer outward from each side of the cell. It should be understood that litho-buffers of different size can be used in different embodiments. Also, litho-buffers of different size can be used for different levels of the same cell. However, in one embodiment, a single litho-buffer size is used for each level of the same cell.
During cell-level-PCT processing, features in the various level layouts of the cell are adjusted to include PCT shapes. For example, in one embodiment, during cell-level-PCT processing, a layout of a given level of a cell is OPC processed to include OPC shapes. In another exemplary embodiment, during cell-level-PCT processing, a layout of a given level of a cell is OPC processed and MPC processed to include both OPC shapes and MPC shapes. The manner in which the PCT shapes are defined and placed can be specified/controlled through a set of PCT rules. The PCT corrections can vary in size, shape, and placement, depending on the particular cell architecture, i.e., layout shapes, sizes, and spacing. The PCT processed cell layouts can be put back into the cell database, i.e., cell library, or can be used to create a new cell database.
In a regular architecture that avoids bends in features of certain chip levels, the PCT corrections are primarily intended to maintain the line width of each feature in critical regions. Therefore, with a cell of regular architecture, the PCT corrections can be relatively simple, such as one-dimensional corrections. For example, the critical dimension (CD) of the gate feature over the diffusion region, i.e., active region, would be important as it defines the transistor length. Whereas the CD of the gate feature over the field region, i.e., non-active region, is not as critical. Similarly, for interconnect features, the line width of the interconnect feature associated with a contact or a via is more important than the line width of the interconnect feature between connection points, i.e., between contacts or vias. In one embodiment, a cell of regular architecture can be defined according to the dynamic array architecture as described in each of co-pending U.S. patent application Ser. Nos. 11/683,402; 12/013,342; 12/013,356; and 12/013,366, which are incorporated in their entirety herein by reference.
One advantage of the regular architecture is that line-end shortening and corner rounding are less of a concern than in an arbitrary architecture that includes many feature bends and corners, which can significantly complicate lithographic resolution. For example, in one embodiment of the regular architecture, diffusion areas have bends and require two-dimensional PCT corrections; however, the gate level layout, contact layout, via layout, and a number of interconnect level layouts include only linear shaped features that require only one-dimensional, i.e., linear, PCT corrections.
FIG. 2A is an illustration showing a layout of a gate level of a cell 219 prior to cell-level-PCT processing, in accordance with one embodiment of the present invention. The cell 219 is defined according to a regular architecture. Therefore, the gate level includes a number of linear features 221 having a common orientation and a regular feature-to-feature pitch. Also, the litho-buffer for the gate level is defined around cell 219 by duplicate instantiations of cell 219, namely cell 219TL, cell 219T, cell 219TR, cell 219R, cell 219BR, cell 219B, cell 219BL, and cell 219L.
FIG. 2B is an illustration showing the gate level layout of cell 219 with cell-level-PCT processing performed thereon, in accordance with one embodiment of the present invention. A number of PCT correction shapes 223 are placed at the ends of a number of the linear features 221 to combat line-end-rounding and line-end-shortening effects. As previously mentioned, because the gate level of cell 219 follows the regular architecture, the PCT correction shapes 223 are simple and one-dimensional, i.e., linear.
The sufficiency of PCT processing of a given cell level can be evaluated by generating a simulation of the as-fabricated aerial image of the given PCT processed cell level, and by comparing the generated simulation of the as-fabricated aerial image of the given PCT processed cell level to an original as-drawn layout of the given cell level. In one embodiment, the as-fabricated aerial image of the cell level is generated using a tool designed to simulate how features of a given layout will appear, i.e., be shaped, when fabricated using specified processes and equipment at a particular semiconductor factory.
In one embodiment, the sufficiency of PCT processing of a given cell level can be evaluated by measuring edge differentials between the feature contour edges in the as-fabricated aerial image simulation and the as-drawn layout feature edges. The as-drawn layout feature edges are represented by the original layout of the cell level prior to PCT processing. If the measured edge differentials are not acceptable, i.e., are too large, the PCT processing of the cell level is refined to reduce the measured edge differentials. If the measured edge differentials are acceptable, the final PCT processed version of the cell level and its as-fabricated aerial image are stored in a cell library, which may be the original cell library or a new cell library. It should be appreciated that the aerial images may be used during parametric extraction and library characterization to improve the accuracy of library models.
Based on the foregoing, it should be understood that the cell-level-PCT processing of each level of each cell is performed in an iterative manner until an acceptable as-fabricated aerial image of the cell level is obtained based on measured edge differentials. Also, it should understood that a library of cells having been PCT processed can be generated and may include the simulated as-fabricated aerial image of each PCT processed level of each cell.
The cell-level PCT processing results and associated as-fabricated aerial images can be placed in a cell library. Then, for a design that uses a cell which has already been PCT processed, the as-fabricated aerial images of the cell can be obtained from the cell library and used in the design layout, rather than using the idealized polygon representation of cell. Because PCT processing capability can vary between different semiconductor fabrication facilities, multiple fab-specific versions of a given PCT processed cell may be created. Therefore, a given fab-specific cell library may be generated, or fab-specific data typing may be used to distinguish between PCT processed cells for different fabs in a common cell library. More specifically, the PCT processed cells and corresponding aerial/post-etch images can be created on separate layout data file layers or could be on individual data types within each layer.
The PCT processed version of a particular cell should be selected from the cell library according to the fabrication facility to be used. Appropriate mapping during cell library export should ensure delivery of the correct cell library to a given customer. Also, the aerial images may be encrypted in the cell library to be kept from view of unauthorized entities. It should be appreciated that by doing cell-level PCT processing and creating an associated PCT processed cell library, post-design processing of the layout data file is greatly reduced. Moreover, when the PCT processed cells are provided to the fabricator, the required PCT processing by the fabricator is significantly reduced, particularly in the front end of line levels.
FIG. 3 is an illustration showing a flowchart of a method for generating a library of PCT processed cells for use in an integrated circuit design, in accordance with one embodiment of the present invention. The method includes an operation 301 for obtaining a cell to be cell-level-PCT processed. The cell obtained in operation 301 can be acquired from an existing cell library, created by modification of a cell acquired from an existing cell library, or created from scratch. The method then proceeds with an operation 303 for performing cell-level-PCT processing on a number of levels of the obtained cell. In one embodiment, the cell-level-PCT-processing includes OPC processing of selected levels of the cell. In another embodiment, the cell-level-PCT-processing includes OPC and MPC processing of selected levels of the cell.
It should be understood that the cell to be cell-level-PCT processed in the method of FIG. 3 may not be associated with a particular chip layout. Therefore, the cell-level-PCT processing of the cell in the method of FIG. 3 is performed in an iterative manner until acceptable as-fabricated aerial images of the selected cell levels are obtained based on measured edge differentials. The method further includes an operation 305 for storing the cell having been cell-level-PCT processed in a cell library. Operations 301-305 are repeated for a number of cells to generate the library of PCT processed cells for use in integrated circuit design. The generated library of PCT processed cells can also include the simulated as-fabricated aerial image of each PCT processed level of each cell.
FIG. 4 is an illustration showing a flowchart of a method for accelerating PCT processing of a semiconductor chip layout, in accordance with one embodiment of the present invention. The method includes an operation 401 for replacing selected cells in a chip layout with corresponding PCT pre-processed cells. Each PCT pre-processed cell represents a particular selected cell having been previously subjected to a cell-level-PCT-processing operation so as to include PCT-based cell layout adjustments. For example, FIG. 5A shows an exemplary chip layout 501 for a given level of a chip. The chip layout 501 includes a section 503 having a number of cells (A-H) placed therein. FIG. 5B shows the exemplary chip layout 501 with selected cells in the section 503 replaced with corresponding PCT pre-processed cells. Specifically, cells having a * designation in the section 503 of FIG. 5B represent cells that have been replaced with corresponding PCT pre-processed cells. Thus, cells A*, B*, C*, E*, and G* represent PCT pre-processed cells, and cells D, F, and H represent original cells, i.e., cells that have not been replaced with PCT pre-processed cells.
It should be understood that the operation 401 may include replacing any number of cells in a chip layout with corresponding PCT pre-processed cells. For example, in one embodiment, all cells in a section of a chip layout may be replaced with corresponding PCT pre-processed cells. In another embodiment, such as that depicted in FIG. 5B, a portion of cells in a section of a chip layout may be replaced with corresponding PCT pre-processed cells. In one embodiment, the selected cells that are replaced in operation 401 with corresponding PCT pre-processed cells are standard cells. In another embodiment, the selected cells that are replaced in operation 401 with corresponding PCT pre-processed cells are non-memory cells, and may or may not be standard cells.
The method of FIG. 4 continues with an operation 403 for performing a chip-wide PCT processing operation on the chip layout for a given chip level. It should be understood that the operation 403 is performed following the operation 401. Therefore, the chip-wide PCT processing operation is performed on the chip layout with the replacement PCT pre-processed cells present in the chip layout. In one embodiment, the chip-wide PCT processing of operation 403 is performed without PCT processing of the PCT pre-processed cells present within the chip layout. FIG. 5C shows the exemplary chip layout 501 with identification of cells having been subjected to the chip-wide PCT processing of operation 403. Specifically, cells having a # designation in the section 503 of FIG. 5C represent cells that have been subjected to the chip-wide PCT processing of operation 403. Therefore, in accordance with the present embodiment, the cells D, F, and H which were not replaced with PCT pre-processed cells were subjected to the chip-wide PCT processing operation, and the PCT pre-processed cells A*, B*, C*, E*, and G* were not subjected to the chip-wide PCT processing of operation 403.
In another embodiment, the chip-wide PCT processing of operation 403 includes PCT processing of the PCT pre-processed cells present within the semiconductor chip layout. In this embodiment, the chip-wide PCT processing of a given PCT pre-processed cell considers the PCT-based cell layout adjustments already present in the given PCT pre-processed cell, thereby accelerating the PCT processing of the chip layout. FIG. 5D shows the exemplary chip layout 501 with identification of cells having been subjected to the chip-wide PCT processing of operation 403. Specifically, cells having a # designation in the section 503 of FIG. 5D represent cells that have been subjected to the chip-wide PCT processing of operation 403. Therefore, in accordance with the present embodiment, the cells D, F, and H which were not replaced with PCT pre-processed cells were subjected to the chip-wide PCT processing operation, and the PCT pre-processed cells A*, B*, C*, E*, and G* were also subjected to the chip-wide PCT processing of operation 403.
The method further includes an operation 405 for recording the chip-wide PCT processed layout for the given chip level on a persistent storage medium. In one embodiment, the persistent storage medium is a computer readable medium.
In one embodiment, the method of FIG. 4 includes another operation for specifying one or more PCT pre-processed cells in the chip layout for PCT processing during the chip-wide PCT processing operation. In this embodiment, these specified PCT pre-processed cells are subjected to PCT processing during operation 403. Also, in this embodiment, non-specified PCT pre-processed cells in the chip layout are not subjected to PCT processing during the chip-wide PCT processing operation.
FIG. 5E shows the exemplary chip layout 501 with specification of PCT pre-processed cells to be PCT processed during the chip-wide PCT processing of operation 403. Specifically, cells having a +designation in the section 503 of FIG. 5E represent PCT pre-processed cells that have been specified for PCT processing during the chip-wide PCT processing of operation 403. Therefore, in accordance with the present embodiment, the A*+, B*+, E*+, and G*+PCT pre-processed cells are to be subjected to the chip-wide PCT processing of operation 403. FIG. 5F shows the exemplary chip layout 501 of FIG. 5E following the operation 403. As shown in section 503 of FIG. 5F, the PCT pre-processed cells A*#, B*#, E*#, and G*# were subjected to the chip-wide PCT processing of operation 403, and the PCT pre-processed cell C* was not subjected to the chip-wide PCT processing of operation 403. Also, section 503 of FIG. 5F shows that the non-PCT pre-processed cells D#, F#, and H# were subjected to the chip-wide PCT processing of operation 403. In one embodiment, non-PCT pre-processed cells within the chip layout are subject to the chip-wide PCT processing of operation 403 by default.
In one embodiment, the PCT processing operations in the method of FIG. 4 include an OPC processing operation. In another embodiment, the PCT processing operations in the method of FIG. 4 include both an OPC processing operation and an MPC processing operation. It should be understood, however, that in other embodiments the PCT processing operations in the method of FIG. 4 can include essentially any type and combination of PCT processing.
In view of the foregoing, in one embodiment, PCT processing of a chip layout is accelerated by replacing a number of cells in a chip layout with PCT pre-processed cells, and through bypassing PCT processing of the PCT pre-processed cells when performing PCT processing on the chip layout. It should be appreciated that bypassing PCT processing of the PCT pre-processed cells when performing PCT processing on the chip layout will accelerate the PCT processing of the chip layout.
In another embodiment, PCT processing of a chip layout is accelerated by replacing a number of cells in a chip layout with PCT pre-processed cells, and through PCT processing of the PCT pre-processed cells when performing PCT processing on the chip layout. In this embodiment, it should be understood that the PCT processing of a given PCT pre-processed cell considers PCT-based cell layout adjustments already present in the given PCT pre-processed cell. Therefore, PCT processing of a PCT pre-processed cell should proceed more rapidly than PCT processing of a cell that has not yet been subjected to PCT processing, thereby accelerating the PCT processing of the chip layout.
In another embodiment, PCT processing of a chip layout is accelerated by replacing a number of cells in a chip layout with PCT pre-processed cells, and through PCT processing of selected PCT pre-processed cells when performing PCT processing on the chip layout, and through bypassing PCT processing of non-selected PCT pre-processed cells when performing PCT processing on the chip layout. In this embodiment, it should be understood that the PCT processing of a given PCT pre-processed cell considers PCT-based cell layout adjustments already present in the given PCT pre-processed cell. Therefore, PCT processing of a PCT pre-processed cell should proceed more rapidly than PCT processing of a cell that has not yet been subjected to PCT processing, thereby accelerating the PCT processing of the chip layout.
Also, bypassing PCT processing of some (non-selected) PCT pre-processed cells when performing PCT processing on the chip layout will accelerate the PCT processing of the chip layout. In this embodiment, the PCT pre-processed cells selected for chip-wide PCT processing may be selected based on design intent. For example, PCT pre-processed cells selected for chip-wide PCT processing may be selected based on timing critical path considerations, leakage considerations, cross-talk noise consideration, manufacturability considerations, or essentially any other consideration or combination of considerations.
The PCT processing of the cells and chip layout in each of the above-described embodiments may include any type of PCT processing operation. In one embodiment, the PCT processing of the cells and chip layout in each of the above-described embodiments includes OPC processing operations. In another embodiment, the PCT processing of the cells and chip layout in each of the above-described embodiments includes OPC and MPC processing operations.
FIG. 6 is an illustration showing a flowchart of a method for processing a semiconductor chip layout for fabrication, in accordance with one embodiment of the present invention. The method includes an operation 601 for obtaining a chip layout having a number of cells placed in a section of the chip layout to form a prescribed integrated circuit. The method also includes an operation 603 for replacing one or more of the number of placed cells with a corresponding PCT pre-processed cell. As previously stated, a given PCT pre-processed cell represents a particular placed cell having been previously subjected to a cell-level-PCT-processing operation so as to include PCT-based cell layout adjustments within the given PCT pre-processed cell.
The method further includes an operation 605 for performing a chip-wide PCT processing operation on a given level of the chip layout to generate a chip-wide PCT processed chip layout for the given level. The method also includes an operation 607 for recording the chip-wide PCT processed chip layout for the given level on a persistent storage medium. In one embodiment, the chip-wide PCT processed chip layout is recorded in a digital format on a computer readable storage medium. The method then proceeds with a decision operation 609 to determine whether chip-wide PCT processing is to be performed on additional chip levels. If additional chip levels are to be PCT processed, the method reverts from operation 609 back to operation 605. Otherwise, the method concludes.
In one embodiment, the chip-wide PCT processing of operation 605 is performed without PCT processing of the PCT pre-processed cells within the chip layout, thereby accelerating the PCT processing of the chip layout for the given chip level. In another embodiment, the chip-wide PCT processing of operation 605 includes PCT processing of the PCT pre-processed cells within the chip layout. The PCT processing of a given PCT pre-processed cell within the chip layout begins with the PCT-based cell layout adjustments present within the given PCT pre-processed cell, thereby accelerating the PCT processing of the chip layout for the given chip level.
In yet another embodiment, prior to operation 605, an operation is performed to specify one or more PCT pre-processed cells in the chip layout for PCT processing during the chip-wide PCT processing of operation 605. Then, during operation 605, the one or more specified PCT pre-processed cells in the chip layout are subjected to the chip-wide PCT processing, and non-specified PCT pre-processed cells in the chip layout are not subjected to the chip-wide PCT processing. Bypassing PCT processing of the non-specified PCT pre-processed cells in the chip layout serves to accelerate PCT processing of the chip layout. Also, because the PCT processing of the specified PCT pre-processed cells within the chip layout begins with the PCT-based cell layout adjustments present within each of the specified PCT pre-processed cells, the PCT processing of the chip layout is further accelerated.
The PCT processing of the cells and chip layout in the method of FIG. 6 may include essentially any type and combination of PCT processing operations. In one embodiment, the PCT processing of the cells and chip layout in the method of FIG. 6 includes OPC processing operations. In another embodiment, the PCT processing of the cells and chip layout in the method of FIG. 6 includes both OPC and MPC processing operations. Also, in one embodiment, the cells placed in the section of the chip layout to form the prescribed integrated circuit are standard cells. In another embodiment, the cells placed in the section of the chip layout to form the prescribed integrated circuit are non-memory cells, and may or may not be standard cells. Additionally, in one embodiment, the operations of the method of FIG. 6 are performed by computer executable program instructions stored on a computer readable medium and executed by a computer.
FIG. 7 is an illustration showing a PCT processing system, in accordance with one embodiment of the present invention. The system includes an input module 701 defined to receive a chip layout for PCT processing. The chip layout includes a number of cells placed in a section of the chip layout to form a prescribed integrated circuit. In one embodiment the placed cells are standard cells. In another embodiment, the placed cells are non-memory cells and may or may not be standard cells. The system also includes a cell substitution module 703 defined to replace one or more of the cells in the chip layout with a corresponding PCT pre-processed cell. As previously stated, a given PCT pre-processed cell represents a particular cell having been previously subjected to a cell-level-PCT-processing operation so as to include PCT-based cell layout adjustments within the given PCT pre-processed cell. In one embodiment, the system includes a cell library 709 that is accessible by the cell substitution module 703. The cell library includes PCT pre-processed cells for use by the cell substitution module 703 in replacing cells in the chip layout.
The system further includes a PCT processing module 705 defined to perform a chip-wide PCT processing operation on the chip layout of specified chip levels to generate a chip-wide PCT processed chip layout for each of the specified chip levels. The PCT processing module 705 may be defined to operate in a selected mode of operation. In a first selectable mode of operation, the PCT processing module 705 performs the chip-wide PCT processing operation without PCT processing of the PCT pre-processed cells within the chip layout. In a second selectable mode of operation, the PCT processing module 705 operates to PCT process the PCT pre-processed cells within the chip layout during the chip-wide PCT processing operation. Also, in the second selectable mode of operation, the PCT processing module 705 operates to begin PCT processing of a given PCT pre-processed cell within the chip layout with consideration of the PCT-based cell layout adjustments already present within the given PCT pre-processed cell.
In a third selectable mode of operation, the PCT processing module 705 operates to PCT process tagged PCT pre-processed cells in the chip layout during the chip-wide PCT processing operation, and operates to skip PCT processing of non-tagged PCT pre-processed cells in the chip layout during the chip-wide PCT processing operation. In the third selectable mode of operation, the PCT processing module 705 operates to begin PCT processing of a tagged PCT pre-processed cell within the chip layout with consideration of the PCT-based cell layout adjustments already present within the tagged PCT pre-processed cell.
The system further includes an output module 707 defined to record the chip-wide PCT processed chip layout, for each of the specified levels of the chip layout, on a persistent storage medium. In one embodiment, the output module 707 operates to record the chip-wide PCT processed chip layout in a digital format on a computer readable storage medium. Each of the input module 701, the cell substitution module 703, the cell library 709, the PCT processing module 705, and the output module 707 are defined as either software, firmware, hardware, or a combination thereof. In this regard, it should be understood that software refers to program instructions that are stored on a computer readable medium and that are capable of being executed by a computer to perform a prescribed function. Also in this regard, it should be understood that firmware refers to circuitry that is defined to operate in a specific manner to perform a prescribed function. For example, firmware may correspond to circuitry for implementing a state machine that is defined to perform one or more prescribed functions. Furthermore, it should be understood that hardware refers to physical equipment defined perform a particular function. For example, hardware may refer to one or more components of a computing system, such as a central processing unit, a memory, an input/output module, a hard drive, etc. Additionally, hardware within the context of the system of FIG. 7 may include essentially any type of PCT processing equipment, such as optical imaging devices by way of example.
The invention described herein can be embodied as computer readable code on a computer readable medium. The computer readable medium is any data storage device that can store data which can thereafter be read by a computer system. Examples of the computer readable medium include hard drives, network attached storage (NAS), read-only memory, random-access memory, CD-ROMs, CD-Rs, CD-RWs, magnetic tapes, and other optical and non-optical data storage devices. The computer readable medium can also be distributed over a network of coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. Additionally, a graphical user interface (GUI) implemented as computer readable code on a computer readable medium can be developed to provide a user interface for performing any embodiment of the present invention.
While this invention has been described in terms of several embodiments, it will be appreciated that those skilled in the art upon reading the preceding specifications and studying the drawings will realize various alterations, additions, permutations and equivalents thereof. Therefore, it is intended that the present invention includes all such alterations, additions, permutations, and equivalents as fall within the true spirit and scope of the invention.

## Claims

1. A method for accelerating process compensation technique (PCT) processing of a semiconductor chip layout, comprising:
operating a computer to replace selected cells in the semiconductor chip layout with corresponding PCT pre-processed cells, wherein each PCT pre-processed cell represents a particular selected cell having been previously subjected to a cell-level-PCT-processing operation so as to include PCT-based cell layout adjustments, wherein the cell-level-PCT processing operation of a given cell includes generation of at least one as-fabricated aerial image of one or more PCT processed levels of the given cell and evaluation of PCT processing adequacy based on the at least one as-fabricated aerial image;
following replacement of the selected cells in the semiconductor chip layout with corresponding PCT pre-processed cells, operating a computer to perform a chip-wide PCT processing operation on the semiconductor chip layout for a given chip level; and
operating a computer to record the chip-wide PCT processed semiconductor layout for the given chip level on a computer readable storage medium.

2. A method as recited in claim 1, wherein the chip-wide PCT processing operation on the semiconductor chip layout for the given chip level is perfolined without PCT processing of the PCT pre-processed cells present within the semiconductor chip layout.

3. A method as recited in claim 1, wherein the chip-wide PCT processing operation on the semiconductor chip layout for the given chip level includes PCT processing of the PCT pre-processed cells present within the semiconductor chip layout.

4. A method as recited in claim 3, wherein the chip-wide PCT processing of a given PCT pre-processed cell considers the PCT-based cell layout adjustments already present in the given PCT pre-processed cell.

5. A method as recited in claim 1, further comprising:
specifying one or more PCT pre-processed cells in the semiconductor chip layout for PCT processing during the chip-wide PCT processing operation; and
PCT processing the one or more specified PCT pre-processed cells in the semiconductor chip layout during the chip-wide PCT processing operation, wherein non-specified PCT pre-processed cells in the semiconductor chip layout are not subjected to PCT processing during the chip-wide PCT processing operation.

6. A method as recited in claim 1, wherein the selected cells in the semiconductor chip layout that are replaced by corresponding PCT pre-processed cells are standard cells.

7. A method as recited in claim 1, wherein the selected cells in the semiconductor chip layout that are replaced by corresponding PCT pre-processed cells are non-memory cells.

8. A method as recited in claim 1, wherein the persistent storage medium is a computer readable medium.

9. A method as recited in claim 1, wherein both the cell-level-PCT-processing operation and the chip-wide PCT processing operation include an optical proximity correction (OPC) processing operation.

10. A method as recited in claim 1, wherein both the cell-level-PCT-processing operation and the chip-wide PCT processing operation include both an optical proximity correction (OPC) processing operation and a mask proximity correction (MPC) operation.

11. A method for processing a semiconductor chip layout for fabrication, comprising:
a) obtaining a chip layout having a number of cells placed in a section of the chip layout to form a prescribed integrated circuit;
b) operating a computer to replace one or more of the number of placed cells with a corresponding process compensation technique (PCT) pre-processed cell, wherein a given PCT pre-processed cell represents a particular placed cell having been previously subjected to a cell-level-PCT-processing operation so as to include PCT-based cell layout adjustments within the given PCT pre-processed cell, wherein the cell-level-PCT processing operation of a given cell includes generation of at least one as-fabricated aerial image of one or more PCT processed levels of the given cell and evaluation of PCT processing adequacy based on the at least one as-fabricated aerial image;
c) operating a computer to perform a chip-wide PCT processing operation on a given level of the chip layout to generate a chip-wide PCT processed chip layout for the given level;
d) operating a computer to record the chip-wide PCT processed chip layout for the given level on a computer readable storage medium; and
e) repeating operations c) and d) for each level of the chip that requires PCT processing for fabrication.

12. A method as recited in claim 11, wherein both the cell-level-PCT-processing operation and the chip-wide PCT processing operation include an optical proximity correction (OPC) processing operation.

13. A method as recited in claim 11, wherein both the cell-level-PCT-processing operation and the chip-wide PCT processing operation include both an optical proximity correction (OPC) processing operation and a mask proximity correction (MPC) operation.

14. A method as recited in claim 11, wherein the number of cells placed in the section of the chip layout to form the prescribed integrated circuit are standard cells.

15. A method as recited in claim 11, wherein the number of cells placed in the section of the chip layout to form the prescribed integrated circuit are non-memory cells.

16. A method as recited in claim 11, wherein the chip-wide PCT processed chip layout is recorded in a digital format on a computer readable storage medium.

17. A method as recited in claim 11, wherein the operations a) through e) are performed by computer executable program instructions stored on a computer readable medium and executed by a computer.

18. A method as recited in claim 11, wherein the chip-wide PCT processing of operation c) is performed without PCT processing of the PCT pre-processed cells within the chip layout.

19. A method as recited in claim 11, wherein the chip-wide PCT processing of operation c) includes PCT processing of the PCT pre-processed cells within the chip layout, and wherein the PCT processing of a given PCT pre-processed cell within the chip layout begins with the PCT-based cell layout adjustments present within the given PCT pre-processed cell.

20. A method as recited in claim 11, further comprising:
prior to operation c), specifying one or more PCT pre-processed cells in the chip layout for PCT processing during the chip-wide PCT processing of operation c); and
during operation c), PCT processing the one or more specified PCT pre-processed cells in the chip layout, wherein the PCT processing of a given PCT pre-processed cell within the chip layout begins with the PCT-based cell layout adjustments present within the given PCT pre-processed cell, and wherein non-specified PCT pre-processed cells in the chip layout are not subjected to PCT processing during the chip-wide PCT processing of operation c).

21. A process compensation technique (PCT) processing system, comprising:
an input module defined to receive a chip layout for PCT processing, wherein the chip layout includes a number of cells placed in a section of the chip layout to form a prescribed integrated circuit;
a cell substitution module defined to replace one or more of the number of cells in the chip layout with a corresponding PCT pre-processed cell, wherein a given PCT pre-processed cell represents a particular cell having been previously subjected to a cell-level-PCT-processing operation so as to include PCT-based cell layout adjustments within the given PCT pre-processed cell, wherein the cell-level-PCT processing operation of a given cell includes generation of at least one as-fabricated aerial image of one or more PCT processed levels of the given cell and evaluation of PCT processing adequacy based on the at least one as-fabricated aerial image;
a PCT processing module defined to perform a chip-wide PCT processing operation on specified levels of the chip layout to generate a chip-wide PCT processed chip layout for each of the specified levels of the chip layout; and
an output module defined to record the chip-wide PCT processed chip layout for each of the specified levels of the chip layout on a persistent storage medium.

22. A system as recited in claim 21, wherein the PCT processing module is defined to perform the chip-wide PCT processing operation without PCT processing of the PCT pre-processed cells within the chip layout.

23. A system as recited in claim 21, wherein the PCT processing module is defined to PCT process the PCT pre-processed cells within the chip layout during the chip-wide PCT processing operation, and wherein the PCT processing of a given PCT pre-processed cell within the chip layout begins with the PCT-based cell layout adjustments present within the given PCT pre-processed cell.

24. A system as recited in claim 21, wherein the PCT processing module is defined to PCT process tagged PCT pre-processed cells during the chip-wide PCT processing operation, and wherein the PCT processing of a given tagged PCT pre-processed cell within the chip layout begins with the PCT-based cell layout adjustments present within the given tagged PCT pre-processed cell, and
wherein during the chip-wide PCT processing operation the PCT processing module is defined to skip PCT processing of non-tagged PCT pre-processed cells in the chip layout.

25. A system as recited in claim 21, further comprising:
a cell library accessible by the cell substitution module, wherein the cell library includes PCT pre-processed cells for use by the cell substitution module in replacing one or more of the number of cells in the chip layout.

26. A system as recited in claim 21, wherein the input module, the cell substitution module, the PCT processing module, and the output module are defined as either software, firmware, hardware, or a combination thereof.

27. A system as recited in claim 21, wherein both the cell-level-PCT-processing operation and the chip-wide PCT processing operation include an optical proximity correction (OPC) processing operation.

28. A system as recited in claim 21, wherein both the cell-level-PCT-processing operation and the chip-wide PCT processing operation include both an optical proximity correction (OPC) processing operation and a mask proximity correction (MPC) operation.

29. A system as recited in claim 21, wherein the chip-wide PCT processed chip layout is recorded in a digital format on a computer readable storage medium.