41 results about "Computational lithography" patented technology

The present invention relates generally to methods and apparatuses for test pattern selection for computational lithography model calibration. According to some aspects, the pattern selection algorithms of the present invention can be applied to any existing pool of candidate test patterns. According to some aspects, the present invention automatically selects those test patterns that are most effective in determining the optimal model parameter values from an existing pool of candidate test patterns, as opposed to designing optimal patterns. According to additional aspects, the selected set of test patterns according to the invention is able to excite all the known physics and chemistry in the model formulation, making sure that the wafer data for the test patterns can drive the model calibration to the optimal parameter values that realize the upper bound of prediction accuracy imposed by the model formulation.

The invention provides an informatics calculation photoetching method, which comprises the following steps of: firstly, establishing a calculation photoetching channel model according to an information theory, then solving optimal mask distribution, optimal photoetching system parameters and process parameters under the information theory, and finally, improving the convergence precision of a calculation photoetching algorithm by adopting the information theory. Therefore, the essence of the method is that a channel model is used for depicting a photoetching system, a photoetching imaging process is abstracted into a channel transmission process, a mask pattern and photoetching imaging are regarded as input and output signals of a channel, and photoetching system parameters, photoetching process parameters and the like are regarded as channel parameters influencing photoetching layout information transmission; the calculation photoetching is adopted to optimize the mask, which is equivalent to the encoding process of the signal; that is to say, an informatics model for calculating photoetching is established, a photoetching pattern information transmission mechanism and rule are researched through adoption of a mathematical method, the theoretical limit for calculating photoetching imaging precision can be obtained, and the convergence precision of a calculation photoetching algorithm is improved.

Disclosed is a method of measuring a target, and a metrology apparatus. In one arrangement the target comprises a layered structure. The layered structure has a first target structure in a first layer and a second target structure in a second layer. The method comprises illuminating the target with measurement radiation using an illumination profile in the illumination pupil (u) that is offset from an imaginary line (IL) in the illumination pupil passing through the optical axis, to allow propagation to a detection region of the detection pupil of an allowed order (v2, v4) of a predetermined diffraction order while limiting propagation to the detection region of an equal and opposite order (v1′, v3′) of that predetermined diffraction order. Scattered radiation of plural double-diffracted allowed diffraction orders (w2, w4) is detected. A characteristic of the lithographic process is calculated using the detected scattered radiation of the predetermined diffraction orders.

The invention provides a computing method for a diffraction field of a double-absorbing-layer alternating phase shift contact hole mask. According to the method, diffraction of the double-absorbing-layer alternating phase shift contact hole mask in photo-etching can be quickly computed. The computing method specifically comprises the following steps of: 1, setting harmonic number reserved in the x direction and setting harmonic number reserved in the y direction; 2, solving components of wave vector of each diffraction order in the tangential direction and the normal direction according to a Floquet condition; 3, performing Fourier series expansion on dielectric constant of a two-dimensional grating on each layer and a reciprocal of the dielectric constant; and 4, solving the diffraction field of an emission region by using an enhanced transmission matrix method. In two orthogonal directions, the Fourier series expansion is performed by selecting the minimum common multiple of cycles of three grating layers in the corresponding orthogonal direction, so that the diffraction of a plurality of layers of two-dimensional mask gratings with different cycles in the two orthogonal directions can be analyzed, and meanwhile, the diffraction field of the double-absorbing-layer alternating phase shift contact hole mask can be quickly solved.

A recording medium stores a program for causing a computer to execute a method of calculating a resist pattern. The method includes: a first step of calculating a light intensity distribution of an optical image formed on the resist, based on the reticle pattern and an exposure condition; a second step of convoluting, using a first diffusion length, the calculated light intensity distribution; a third step of calculating a representative light intensity from the calculated light intensity distribution or the convoluted light intensity distribution; a fourth step of correcting the convoluted light intensity distribution by adding, to the convoluted light intensity distribution, a correction function including a first function given by:{∑k=0n⁢(ak⁢Jk)}⁢exp⁡(-α⁢⁢J)where J is the distribution of the representative light intensity; and a fifth step of calculating the resist pattern based on the corrected light intensity distribution and a slice level set in advance.

The invention provides a computational lithography method for optical proximity effect correction. The computational lithography method comprises the following steps: an input layout design document is decomposed into a first layout part and a second layout part according to the value of the process factor, wherein the process factor of the first layout part is lower than a preset threshold, and the process factor of the second layout part is higher than a preset threshold; the first layout part and the second layout part are processed separately; and the processed first layout part and the processed second layout part are matched and combined. Because the first layout part and the second layout part are processed separately, the processing quality is improved, there is no need to iteratively execute the optical proximity correction inspection step and the hot spot correction step, and the output speed of layout design documents is improved. The invention also provides a computationallithography system for optical proximity effect correction.

The present application discloses a mask plate processing method and device in computational lithography. The method comprises acquiring the length and the direction of the side of a polygon by the vertex data of the polygon; defining the data format of the polygon according to the length and the direction of the side; and enabling a mask plate pattern to perform storage, reading, and transmissionin accordance with the data format. Compared with the prior art, the method disclosed in the present application reduces the storage space of the mask plate pattern by storing the sides of the polygon in the mask plate pattern, and enables the fast reading and transfer of the data of the mask plate pattern between computer programs. Moreover, when a mask plate pattern function is obtained, a basic pattern function is linearly combined based on the direction of the sides in the polygon, thereby improving the efficiency of the computational lithography.

This application relates to the technical field of integrated circuit manufacturing, and discloses a computational lithography modeling method and device. In this method, the optical module group is determined by obtaining the type of the graphic unit contained in the test pattern, and then according to the optical module group, the obtained Parameters of the physical optics model. Calculate the ideal light intensity distribution of the optical module group on the photoresist, and obtain the parameters of the photochemical model according to the ideal light intensity distribution and the photochemical reaction excited by the optical module group on the photoresist. Then simulate the boundary position of the test pattern formed on the photoresist, and obtain the critical dimension simulation data of the test pattern, if the fitting error between the critical dimension measurement data and the critical dimension simulation data is not greater than the preset allowable error, a computational lithography model is established. The computational lithography modeling method disclosed in the present application effectively improves the accuracy of the computational lithography model by establishing different optical modules to simulate different graphics units.

Optical proximity correction (OPC) based computational lithography techniques are disclosed herein for enhancing lithography printability. An exemplary mask optimization method includes receiving an integrated circuit (IC) design layout having an IC pattern; generating target points for a contour corresponding with the IC pattern based on a target placement model, wherein the target placement model is selected based on a classification of the IC pattern; and performing an OPC on the IC pattern using the target points, thereby generating a modified IC design layout. The method can further include fabricating a mask based on the modified IC design layout. The OPC can select an OPC model based on the classification of the IC pattern. The OPC model can weight the target placement model.

The invention relates to the technical field of the photolithographic process for semiconductor production and particularly relates to a photolithographic process resolution enhancing method and device based on multi-target optimization. The method comprises steps of obtaining regional division of an illumination light source through a method of dividing a plurality of circles to be overlapped foroptimizing the light source; determining an initial position of a sub-resolution auxiliary graph SRAF position variable for optimizing a mask; establishing a population of optimization variables by using a real number encoding method; determining an evaluation standard function of a multi-target optimization strategy for a single chromosome in the population by calculating a photolithographic model; repeatedly carrying out evaluation-selection-crossover-variation calculation of the current population by using the genetic evolution algorithm to obtain iterative update of the evaluation standard function; decoding a final population to obtain a solution set Pareto support solution of the multi-target optimization strategy.

The present invention provides a computational lithography method for optical proximity effect correction. The computational lithography method decomposes the input layout design file into a first layout part and a second layout part according to the value of the process factor, wherein the process factor of the first layout part is lower than a preset threshold, and the second layout part is The process factor of the layout part is greater than the preset threshold; then the first layout part and the second layout part are processed respectively; then, the processed first layout part and the second layout part are matched and merged layout section. Since the first layout part and the second layout part are processed separately, the processing quality is improved, so it is no longer necessary to iteratively perform the step of correcting the optical proximity effect and the step of correcting the hot spot, thereby improving the output speed of the layout design file. The present invention also provides a computational lithography system for optical proximity effect correction.

The invention relates to a method for calculating channel capacity and imaging error lower limit of a coherent imaging photoetching system. The method comprises the steps of rasterizing a mask pattern M; expressing a value of a pixel point A on a mask image M with a binary random variable X, and expressing a value of a pixel point B, corresponding to the pixel point A, on a photoresist image Z with a binary random variable Y; viewing the coherent photoetching system as a binary channel, wherein the X and the Y are respectively an input signal and an output signal of the binary channel; calculating probability pX when the X is equal to 1; calculating transfer probability pij between the X and the Y; calculating probability pY when the Y is equal to 1, and further calculating mutual information I (X; Y) between the X and the Y; taking the maximum value C-bar of the mutual information as the channel capacity; and calculating an image error theoretical lower limit of the coherent photoetching system according to the channel capacity C-bar. By the method, a theoretical basis and a simulation basis can be provided for deeper understanding of an image information transmission mechanism and development of an advanced calculation photoetching technology in the photoetching system.

The invention discloses a deep learning method for computational lithography, which can improve the optimization speed and convergence performance of the traditional OPC method, and can be used for both deep ultraviolet DUV lithography and extreme ultraviolet EUV lithography. Firstly, the gradient iterative algorithm is expanded and its first steps are intercepted, combined with the imaging model of the lithography system and the photoresist model, a forward model-driven convolutional neural network MCNN, namely the encoder, is created. Create a decoder corresponding to the encoder, connect the output of the MCNN to the input of the decoder, use a certain distance between the input of the MCNN and the output of the decoder as a cost function, and train the parameters of the MCNN. The training set samples are input into MCNN, and the parameters in MCNN are optimized to minimize the error between the input of MCNN and the output of the decoder. After the training is completed, the MCNN is separated from the decoder, and the OPC mask graphics corresponding to other circuit layouts can be obtained by using the MCNN.

The invention discloses a computational lithography method for a model-driven convolution neural network (MCNN), and the method can improve the computation speed and convergence performance of OPC (optical proximity correction) method. The technical scheme includes: expanding and truncating the gradient iterative algorithm, and constructing a model-driven convolution neural network (MCNN); based on an imaging model of a lithography system, constructing a decoder corresponding to the MCNN; bringing the MCNN and the decoder to end-to-end connection, and subjecting the MCNN to the following training: optimizing the parameters of the MCNN by back propagation algorithm to minimize the error between the input data of MCNN and the decoder; separating the decoder from the MCNN at the end of the training; inputting a to-be-optimized circuit layout into the trained MCNN so as to obtain an estimated result of an OPC mask; taking the estimated result of OPC mask as the initial value, and carryingout iterative updating on the set number of times of the mask by gradient iterative algorithm, thus obtaining the final OPC mask optimization result.

The invention belongs to the field of computational lithography, and discloses a method for correcting the proximity effect of an electron beam based on a neural network. The present invention first corrects the dose of the designed training layout through any kind of proximity effect dose correction method, then adjusts the neural network parameters, and performs neural network training on the training layout according to the prescribed input method to obtain an adaptive neural network. Network, and finally predict the correction dose of any exposure layout according to the specified input method. The invention realizes the correction of the proximity effect of the electron beam based on the neural network, and solves the correction calculation of the proximity effect of the electron beam exposure. On the basis of ensuring high-precision correction, the calculation efficiency of the correction is greatly improved, and it has high calculation accuracy and high calculation efficiency. Efficiency and other characteristics.