Density calculation method and system for integrated circuit physical verification

Abstract

The application provides a density calculation method and system for integrated circuit physical verification, comprising the following steps: combing a density calculation process to obtain a standardized density calculation process; defining corresponding options for constraint conditions that may occur in each step, and using corresponding instructions to express the options; reading a set of instructions input by a user, and performing density calculation according to constraint conditions set by the user. The technical scheme of the application has an intuitive and easy-to-understand density calculation mode, and is convenient to maintain and extend.

Description

Technical Field

[0001] This invention relates to the field of physical verification technology for integrated circuits, and particularly to a density calculation method and system for physical verification of integrated circuits. Background Technology

[0002] In integrated circuit (IC) design and manufacturing, physical verification is a critical step to ensure the physical integrity, manufacturability, and reliability of chip designs. Density checking is a special type of rule-based check within physical verification. Areas with excessively high or low density can affect the consistency of the device model and impact chip yield; therefore, density calculation is necessary. Density calculation in physical verification refers to calculating the area ratio of circuit elements within a certain range to evaluate the density of circuit elements in the chip layout, obtain the density distribution in different areas, and use this information for density checking to optimize the circuit design.

[0003] Density calculations in practical chip design involve many constraints, such as the calculation range, effective area, pattern width, and pattern spacing. These constraints can be customized and are scalable. Currently, mainstream physical design and verification tools include Cadence PVS, Synopsys ICV, and Mentor Calibre. Taking Mentor Calibre as an example, its physical verification language SVRF (Standard Verification Rule Format) describes density calculations by defining the keyword DENSITY and passing in relevant parameters. It uses complex density calculation expressions to represent some constraints. The functional meanings of each component of the expression are obscure, involving built-in functions, logical judgments, and numerical calculations, requiring users to analyze them themselves. Although theoretically highly scalable, it is difficult for ordinary users to understand and practically difficult to extend. For example, the rule PO.DN.3 described by SVRF under the T28 process node means: the local minimum density of the chip is greater than or equal to 10% (the variable PO_DN_3 = 0.1 in the rule), as shown below. Figure 1 :

[0004] The specific analysis of each part of rule PO.DN.3 is as follows:

[0005] (1) Determine the range of density calculation: The input layer of the rule is ALL_POLY, the exclusion layer is EXC, and the effective density calculation range is obtained by removing the exclusion layer from the input layer;

[0006] (2) Exclusion layer operation: Exclusion layer EXC is scaled down (fill operation) to get layer EXC_M. B1 means to ignore part of the graphics in EXC_M (the graphics themselves have narrow gaps or there are narrow gaps between graphics), and B means to enlarge B1.

[0007] (3) DENSITY syntax and various customized constraints: Define density checking methods and some constraints. The density expression is used to determine whether the calculation results meet the density value constraints. It contains four components, and the functional analysis of each component is as follows:

[0008] "!AREA(B)" indicates a constraint to determine the coverage of the excluded layer after it has been enlarged.

[0009] "~(AREA(A)-PO_DN_3_E*PO_DN_3_E)*!!(AREA(A)-PO_DN_3_E*

[0010] "PO_DN_3_E)" indicates the area constraint of region A;

[0011] “AREA(N) / AREA(D)” represents the density value e_density after removing the exclusion layer;

[0012] "!~(AREA(ALL_POLY) / AREA(CHIP)-PO_DN_3)+!(AREA(ALL_POLY)

[0013] " / AREA(CHIP)-PO_DN_3)" indicates whether the original density i_density satisfies the constraints.

[0014] (4) Graphic width constraint: Determine whether the width of the graphic meets the constraint.

[0015] Based on the above analysis, existing density calculation methods have the following drawbacks:

[0016] The algorithm flow for density calculation lacks intuitiveness: the rule description adopts a process-oriented approach, making it difficult to intuitively understand the algorithm flow for density calculation; the descriptions of constraints are scattered, and the order of constraint judgment lacks intuitiveness.

[0017] The rule description language is obscure and difficult to understand: the density calculation method relies on mathematical expressions to determine constraints, which is difficult for users to understand; in addition, the rules use a large number of keywords and intermediate variables, requiring contextual understanding and finding correspondences to infer the specific meaning of each line of description, further increasing the difficulty of understanding the rules.

[0018] The maintainability of rule writing is not strong: Although implementing the algorithm flow in the user interface is theoretically easy to extend and more flexible, this writing method and meaning are difficult for users to understand, and the maintenance of the rules is more difficult. Summary of the Invention

[0019] The purpose of this invention is to provide a density calculation method and system for physical verification of integrated circuits, thereby solving the technical problems of the density calculation process being not intuitive and the calculation method being obscure and difficult to understand in the prior art.

[0020] In this embodiment of the invention, a density calculation method for integrated circuit physical verification is provided, comprising:

[0021] The density calculation process was streamlined to obtain a standardized density calculation process;

[0022] Define corresponding options for the constraints that may occur in each step, and use corresponding instructions to express the options;

[0023] Read the user's input instruction set and perform density calculations based on the user-set constraints.

[0024] In this embodiment of the invention, the standardized density calculation process includes:

[0025] Determine the scope of global density calculation and the method for local density calculation;

[0026] Calculate the density of the current window;

[0027] Determine whether the density of the current window meets the density constraint. If not, output the violation window directly.

[0028] In this embodiment of the invention, calculating the density of the current window includes:

[0029] Determine if an exclusion layer exists.

[0030] If there is no exclusion layer, the density of the current window is the original density;

[0031] If an exclusion layer exists, the density of the front window is the density after removing the exclusion layer.

[0032] In this embodiment of the invention, determining whether the density of the current window satisfies the density constraint includes:

[0033] If there is no exclusion layer, the original density is used to determine whether the current window satisfies the constraints;

[0034] If an exclusion layer exists, it is first necessary to determine whether the exclusion layer meets the set constraints. If not, the density calculation is exited. If it does, it is necessary to determine whether an original density judgment option exists. If it does, it is necessary to simultaneously determine whether the original density and the density after removing the exclusion layer both meet the density constraints. If not, it is only necessary to determine whether the density after removing the exclusion layer meets the density constraints.

[0035] In this embodiment of the invention, whether the exclusion layer meets the set constraints includes:

[0036] Determine if the area constraint of the valid region is met. If not, end the density calculation process. Otherwise, determine if the width constraint of the graphic is met. If not, end the density calculation process. Otherwise, determine if the coverage constraint after the enlarged exclusion layer is met. If not, end the density calculation process. Otherwise, calculate the density of the current window.

[0037] In this embodiment of the invention, the options corresponding to the constraints involved in density calculation include:

[0038] -global_region: The global density calculation region, with sub-options including:

[0039] -inside_of: the range to be calculated, and -exclude: the range not to be calculated;

[0040] -local_region: Specifies the local density calculation method;

[0041] -fill_exclude: Excludes layer expansion operations. Its sub-options include:

[0042] -remain_area: Area constraint of the effective region; -with_width: Width constraint of the graphic; -full_covered_by_size_up: Coverage constraint;

[0043] -use_idensity: Original density check option, specifies that the original density i_density needs to be calculated and judged to meet the density constraints during density check.

[0044] In this embodiment of the invention, a density calculation system for physical verification of integrated circuits is also provided, which employs the aforementioned density calculation method for physical verification of integrated circuits when performing physical verification of integrated circuits.

[0045] Compared with existing technologies, the density calculation method for integrated circuit physical verification of this invention, starting from the algorithm level, re-organizes the density calculation process, designs a clear density calculation flow to implement various complex constraints, and provides good scalability in the algorithm. Starting from the rule description language, it uses a user-friendly descriptive form to express density calculation. Taking the window as an object, it uses options to describe the attributes or behaviors that the window object may have in the density calculation. Users only need to modify the option settings according to their own needs in the user language interface, avoiding the obscure and redundant expressions of other descriptive methods. The option form intuitively describes the constraints involved in the density calculation, and provides a certain degree of scalability through sub-options. The density calculation flow in the option form is implemented in the internal algorithm. The corresponding algorithm flow is executed according to different option settings to find windows with density violations. Compared with the methods of existing technologies, the density calculation solution proposed in this invention is simpler and more intuitive, both in terms of internal algorithm level and external user level. It enhances the readability and maintainability of rule writing, and reduces the user's learning time and learning cost. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the code for density calculation using existing technology.

[0047] Figure 2 This is a schematic diagram of the standardized density calculation process according to an embodiment of the present invention.

[0048] Figure 3 This is a schematic diagram of ignoring patterns or narrow gaps between patterns before layer magnification in an embodiment of the present invention.

[0049] Figure 4 This is a schematic diagram of the code for calculating density using the density calculation method of integrated circuit physical verification. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0051] The implementation of the present invention will be described in detail below with reference to specific embodiments.

[0052] In this embodiment of the invention, a density calculation method for integrated circuit physical verification is provided, comprising:

[0053] The density calculation process was streamlined to obtain a standardized density calculation process;

[0054] Define corresponding options for the constraints that may occur in each step, and use corresponding instructions to express the options;

[0055] Read the user's input instruction set and perform density calculations based on the user-set constraints.

[0056] It should be noted that in this embodiment of the invention, the OOVF language is used to describe the corresponding options, and each option is expressed by an instruction with the same name. The options corresponding to the constraints involved in density calculation include:

[0057] -global_region: The global density calculation region, with sub-options including:

[0058] -inside_of: the range to be calculated, and -exclude: the range not to be calculated;

[0059] -local_region: Specifies the local density calculation method;

[0060] -fill_exclude: Excludes layer expansion operations. Its sub-options include:

[0061] -remain_area: Area constraint of the effective region; -with_width: Width constraint of the graphic; -full_covered_by_size_up: Coverage constraint;

[0062] -use_idensity: Original density check option, specifies that the original density i_density needs to be calculated and judged to meet the density constraints during density check.

[0063] like Figure 2 As shown in the embodiment of the present invention, the standardized density calculation process includes steps S1-S3. These will be described below.

[0064] Step S1: Determine the global density calculation range and the local density calculation method.

[0065] It should be noted that in step S1, the global density calculation range is set by the option -global_region, and its sub-options include: -inside_of: the range to be calculated, and -exclude: the range not to be calculated.

[0066] Step S2: Calculate the density of the current window.

[0067] It should be noted that when calculating the current window density, it is first necessary to determine whether an exclusion layer exists. If no exclusion layer exists, the window density is the original density i_density; if an exclusion layer exists, the window density is the density e_density after removing the exclusion layer. In this embodiment, the exclusion layer setting option is -exclude.

[0068] Step S3: Determine whether the density of the current window meets the density constraint. If not, output the violation window directly.

[0069] It should be noted that in this step, if no exclusion layer exists, the original density i_density is used to determine whether the window satisfies the constraints. If an exclusion layer exists, it is first necessary to determine whether the exclusion layer satisfies the set constraints. If not, the density calculation is exited. If it does, it is necessary to check whether the -use_idensity option exists. If it exists, it is necessary to simultaneously check whether the original density i_density and the density e_density after removing the exclusion layer both satisfy the density constraints. If it does not exist, it is only necessary to check whether the density e_density after removing the exclusion layer satisfies the density constraints.

[0070] The exclusion layer's compliance with the defined constraints includes:

[0071] Determine if the area constraint of the valid region is met. If not, end the density calculation process. Otherwise, determine if the width constraint of the graphic is met. If not, end the density calculation process. Otherwise, determine if the coverage constraint after the enlarged exclusion layer is met. If not, end the density calculation process. Otherwise, calculate the density of the current window.

[0072] It should be noted that the constraints of the exclusion layer are set through the relevant sub-options under the exclusion layer's expansion operation (-fill_exclude). These include not only sub-options such as the area constraint of the effective region (-remain_area), the width constraint of the graphic (-with_width), and the coverage constraint (-full_covered_by_size_up), but also sub-options within these sub-options. For example, under the coverage constraint (-full_covered_by_size_up), the sub-option -ignore_gap can be set, which means whether to ignore graphics with narrow gaps within the exclusion layer or graphics with narrow gaps between them before scaling up. Figure 3As shown, assuming the user sets -full_covered_by_size_up{-ignore_gap10}, and there is a narrow gap of 9 in graphic A (9 < 10), graphic A is ignored before the exclusion layer is enlarged. The gap between graphics B and C is 9 (9 < 10), and graphics B and C are ignored before the exclusion layer is enlarged.

[0073] In this embodiment of the invention, if the exclusion layer satisfies the set constraints, the density of the current window is calculated, including:

[0074] Determine if the original density check option -use_idensity exists.

[0075] If the original density check option exists, calculate the original density and determine whether the original density and the density after removing the exclusion layer meet the constraints.

[0076] If the original density check option is not available, then directly determine whether the density after removing the exclusion layer meets the constraint conditions.

[0077] like Figure 4 As shown, this is the density calculation method implemented using the aforementioned integrated circuit physical verification. Figure 1 The density calculation in the text is explained below:

[0078]

[0079]

[0080]

[0081] In this embodiment of the invention, a density calculation system for integrated circuit physical verification is also provided, which employs the aforementioned density calculation method for integrated circuit physical verification when performing physical verification on integrated circuits. It should be noted that the density calculation system for integrated circuit physical verification can be implemented using computer software or a combination of computer hardware and software; this invention does not impose any limitations on this.

[0082] In summary, the density calculation method for integrated circuit physical verification of this invention, starting from the algorithm level, re-organizes the density calculation process, designs a clear density calculation flow to implement various complex constraints, and provides good scalability within the algorithm. Starting from the rule description language, it uses a user-friendly descriptive form to express density calculation, using windows as objects and employing options to describe the attributes or behaviors that window objects may exhibit during density calculation. Users only need to modify the option settings according to their needs in the user interface, avoiding the obscure and redundant expressions of other descriptive methods. The option format intuitively describes the constraints involved in density calculation and provides a certain degree of scalability through sub-options. The internal algorithm implements the density calculation flow in the form of options, executing the corresponding algorithm flow according to different option settings to find windows with density violations. Compared with existing methods, the density calculation solution proposed in this invention is simpler and more intuitive, both from the internal algorithm level and the external user level, enhancing the readability and maintainability of rule writing, and reducing the user's learning time and cost.

[0083] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A density calculation method for physical verification of integrated circuits, characterized in that, include: The density calculation process was streamlined to obtain a standardized density calculation process; Define corresponding options for the constraints that may occur in each step, and use corresponding instructions to express the options; Read the user's input instruction set and perform density calculations based on the user-set constraints; The standardized density calculation process includes: Determine the scope of global density calculation and the method for local density calculation; Calculate the density of the current window; Determine whether the density of the current window meets the density constraint. If not, output the violation window directly. The standardized density calculation process includes calculating the density of the current window, which includes: Determine if an exclusion layer exists. If there is no exclusion layer, the density of the current window is the original density; If an exclusion layer exists, the density of the front window is the density after removing the exclusion layer; In the standardized density calculation process, determining whether the density of the current window satisfies the density constraint includes: If there is no exclusion layer, the original density is used to determine whether the current window satisfies the constraints; If an exclusion layer exists, it is first necessary to determine whether the exclusion layer meets the set constraints. If it does not meet the constraints, the density calculation is exited. If it does meet the constraints, it is necessary to determine whether there is an original density judgment option. If it does, it is necessary to determine whether the original density and the density after removing the exclusion layer meet the density constraints. If it does not, it is only necessary to determine whether the density after removing the exclusion layer meets the density constraints. Determine whether the exclusion layer meets the set constraints, including: Determine if the area constraint of the valid region is met. If not, end the density calculation process. Otherwise, determine if the width constraint of the graphic is met. If not, end the density calculation process. Otherwise, determine if the coverage constraint after the enlarged exclusion layer is met. If not, end the density calculation process. Otherwise, calculate the density of the current window.

2. The density calculation method for integrated circuit physical verification as described in claim 1, characterized in that, The options corresponding to the constraints involved in density calculation include: -global_region: The global density calculation region, with sub-options including: -inside_of: the range to be calculated, and -exclude: the range not to be calculated; -local_region: Specifies the local density calculation method; -fill_exclude: Excludes layer expansion operations. Its sub-options include: -remain_area: Area constraint of the effective region; -with_width: Width constraint of the graphic; -full_covered_by_size_up: Coverage constraint; -use_idensity: Original density check option, specifies that the original density i_density needs to be calculated and judged to meet the density constraints during density check.

3. A density calculation system for physical verification of integrated circuits, characterized in that, When performing physical verification of integrated circuits, the density calculation method for physical verification of integrated circuits as described in claim 1 is adopted.

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