KR20070094190A - Method for correcting optical proximity effect - Google Patents

Abstract

A method for correcting an optical proximity effect is provided to correct distortion due to the optical proximity effect by performing an OPC(Optical Proximity Correction) verification process. A test mask for target patterns is manufactured(201). The target patterns are transferred onto a wafer by using the test mask(202). CD data for the target patterns are measured(203). A model calibration and an OPC recipe are produced by using the CD data(204,205). A first OPC process is performed on an entire area of the mask by using a model and a recipe(206). A first verification process for a result of the first OPC process is performed(207). A second OPC process for erroneous patterns is performed selectively and a second verification process for a result of the second OPC process is performed(212,213). A mask is manufactured by using the verified result(209).

Description

Method for correcting optical proximity effect

1 is a flowchart schematically illustrating a conventional optical proximity effect correction method.

2 is a flowchart schematically illustrating an optical proximity effect correction method according to an exemplary embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly, to a method of correcting an optical proximity effect (OPE) when fabricating a photo mask.

 As the degree of integration of semiconductor devices increases, it is required to implement finer patterns in photo lithography. However, as the pattern is miniaturized, an optical proximity phenomenon OP due to influence between neighboring patterns is generated during the exposure process. In order to overcome this, a method of suppressing OPE generation by correcting a pattern layout on a photo mask for transferring a pattern, for example, optical proximity correction (OPC), has been performed.

1 is a flowchart schematically illustrating a conventional optical proximity effect correction method.

Referring to FIG. 1, first, a layout of a target pattern to be transferred onto a wafer is designed, and a test mask in which the target pattern layout is formed as a test pattern is formed (11).

Subsequently, a wafer process including a photolithography or / and etching process including an exposure and development process onto an actual wafer is performed using a test mask (12). Thereafter, the line width (CD) of the pattern formed on the wafer is measured (13).

Model calibration is performed for the OPC using the measured CD data (14). Such model calibration can be understood as a process based on model based OPC. Model-based OPC uses models set up for various types of pattern shape features prepared in advance to simulate the shape difference of the mask pattern and thereby the pattern transferred on the wafer, based on the calculation result. Can be understood as a method of correcting a mask pattern. Thus, after model calibration, an optimal recipe, preferably required for OPC, is created (15).

The OPC is performed using the calibrated model and the recipe (16), and the operation of verifying whether or not the OPC is properly performed through the contour contour (simulation contour) of the pattern (17). In this case, if the simulation contour through the OPC is out of the error tolerance, model calibration or recipe correction is performed again to re-perform the OPC over all mask regions (18).

If the model that performed the OPC and the model used for verification after the completion of the OPC are the same, the same model is used, so all the patterns must satisfy within the error tolerance specified when performing the OPC in the verification step. Since the verification is different, different results can be seen even when using the same model.

This process is repeated to produce the actual mask if the resulting simulation contour is within error tolerance (19).

However, in this case, even after the OPC is completed, even if the error tolerance is out of the specified error range in only a certain area within a certain pattern or mask through OPC verification, a new model or a new recipe may be used for all databases. OPC is running again. As a result, a considerable amount of time is required to manufacture a mask through OPC. Therefore, there is a demand for the development of an OPC method that can further reduce the time required to manufacture a mask.

An object of the present invention is to propose a method of correcting an optical proximity effect (OPE) within a shorter time.

According to an aspect of the present invention, a test mask of target patterns may be fabricated, transfer of the patterns onto a wafer using the test mask, and line width (CD) data of the patterns. Measuring, generating a model calibration and optical proximity effect correction (OPC) recipe using the linewidth data, and first optical proximity to the entire mask area using the model and recipe Performing effect correction (OPC), first verifying the results of the first optical proximity effect correction (OPC), and selectively performing second optical proximity only on patterns in which an error has occurred during the first verification Re-executing effect correction (OPC) and second order verification, and fabricating a mask using the optical proximity effect correction (OPC) verified results. A method of correcting the proximity effect (OPE) is presented.

Or fabricating a test mask of target patterns, transferring the patterns onto a wafer with a plurality of exposure conditions using the test mask, measuring linewidth data of the patterns associated with the exposure conditions, A model calibration step of generating a plurality of models associated with the exposure conditions using the linewidth data, an optical proximity effect correction (OPC) recipe generation step for the models, the model and recipe Performing first optical proximity effect correction (OPC) using the first optical proximity effect correction (OPC), first verifying the results of the first optical proximity effect correction (OPC) using the models, and error in the first verification Selectively performing secondary optical proximity effect correction (OPC) on the generated patterns using the recipes, the secondary optical proximity effect An optical proximity effect (OPE) correction method comprising selectively performing second-order verification on the corrected (OPC) result and manufacturing a mask using the optical proximity effect corrected (OPC) verified result. .

Generating an error marker for the patterns in which an error has occurred during the optical proximity effect correction (OPC) verification, and backing up the error result to a differentiated data layer number to perform the secondary The method may further include performing optical proximity effect correction (OPC) only on the pattern in which the error occurs.

The second optical proximity effect correction (OPC) and the second verification may be performed only on the region selected by selecting the region including the error pattern.

The second optical proximity effect correction (OPC) and the second verification step may be repeated until the verification result of the patterns is determined within a set acceptance range.

According to the present invention, the optical proximity effect (OPE) can be corrected within a shorter time, and thus the manufacturing time can be effectively reduced when manufacturing the mask through the optical proximity effect correction.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, it should not be construed that the scope of the present invention is limited by the embodiments described below. Embodiments of the invention are preferably to be interpreted as being provided to those skilled in the art to more fully describe the invention.

In the embodiment of the present invention, in the OPC verification step after performing the optical proximity effect correction (OPC), selectively selecting only a specific region or / and specific patterns that deviate from a specified error tolerance, and select the selected patterns. Only the models or recipes that are different from the models or recipes used in the OPC verification step are applied. Only partially re-execute OPC for the selected patterns (or regions). Therefore, since the OPC is not performed for all the areas in the conventional case, the time required for manufacturing the mask through the OPC can be considerably effectively reduced.

2 is a flowchart schematically illustrating an optical proximity effect correction method according to an exemplary embodiment of the present invention.

Referring to FIG. 2, the OPC method according to the embodiment of the present invention designs a layout of a target pattern to be transferred onto a wafer, and forms a test mask in which the target pattern layout is formed as a test pattern (201). This test mask can be understood as being for the shape of the target patterns to be formed on the actual wafer.

Thereafter, the test mask is used to perform a wafer process including photolithography and / or etching processes including exposure and development processes onto an actual wafer (202). In this case, under various exposure conditions, for example, at an optimal exposure energy condition or at an optimal focus condition, an over-exposure condition, an under exposure condition, and a minus focus condition may be used. Taking into account a variety of different exposure conditions, such as when or a plus focus condition, the wafer process is performed by varying the exposure conditions for each exposure shot on one wafer (or multiple wafers). It is preferable to carry out.

Thereafter, line widths (CDs) of respective patterns formed on the wafer are measured (203). In this case, in the conventional case, the CD measurement of each pattern is performed only for the pattern when performed at the optimum exposure energy and the optimum focus condition, whereas in the exemplary embodiment of the present invention, the result of the wafer process performed at various different exposure conditions is performed. Perform CD measurements on the patterns. Accordingly, measurement data of CDs of respective transferred patterns according to different exposure conditions may be extracted.

The plurality of CD measurement data may be used to detect a weak point due to a process window when performing subsequent OPC verification, and also partially OPC to an area where an error occurs. When re-running, it can be used to apply any different models to the error region.

A plurality of model calibrations are performed for the OPC using the measured plurality of CD data (204). Such model calibration can be understood as a process based on model-based OPC. Typical model calibration is performed using only the pattern shape or feature model by the optimal exposure energy condition and the optimal focus condition, but embodiments of the present invention utilize various feature models using CD measurement data according to various different exposure conditions. A plurality of model calibrations are performed according to respective exposure conditions.

Subsequently, after a plurality of model calibrations are completed, a task of optimizing a recipe to perform OPC is performed. At this time, the optimization of the respective recipes for a plurality of model calibration results are performed in parallel. That is, a plurality of OPC recipes corresponding to respective exposure conditions are created (205).

The plurality of calibrated models or the plurality of recipes is advantageous when the mask is fabricated by including at least two or more regions having different pattern densities, such as in the case of DRAM memory devices. For example, in the case of a DRAM device, a full chip region may be largely divided into a cell and core region and a peripheral region. In this case, the cell and core regions have a larger pattern density than the peripheral region, and are mainly composed of patterns having two dimensions rather than patterns having one dimension.

The change in pattern density for each region causes relatively less etching bias in the cell and core regions than in the peripheral region having a low density during the etching process. In addition, in the case of 1-dimensional pattern, the unit division for OPC may be relatively large, but in the case of 2-dimensional pattern, a relatively small division rule should be applied to secure pattern fidelity. Can meet your desired goals Therefore, an optimized OPC can be achieved only by applying a different model or recipe from the same model or the same recipe that performed the OPC to the patterns in which the OPC error has occurred.

To this end, an embodiment of the present invention creates a plurality of calibrated models or a plurality of recipes.

Preferably, OPC is performed using the optimized model and recipes (206), and OPC verification using a plurality of models is performed on the OPC results (207). At this time, in the OPC verification step, basically the same model as that of the OPC may be used. In addition, the OPC error in the process window may be detected by using a plurality of models according to different exposure conditions generated above.

If an error value obtained in the verification process is determined (208) for a set or given error acceptance range, and is determined within an error acceptance range, a mask is produced (209). However, when the error value is out of the error acceptance range, an error marker is assigned to a specific pattern or a specific region where an error occurs (211).

The generated error markers go through the process of determining whether the site meets the target, and if it is determined that the site must be controlled within the defined range, an appropriate model or recipe is applied to the site. To only partially rerun the OPC for that region (or pattern) (212). At this time, since the previous wafer process 202, CD measurement 203, model calibration 204, recipe 205, and the like are measured or generated in association with various exposure conditions, the OPC or the appropriate model or recipe is used. And verification can be performed again.

OPC data, which is the result of an error marker being generated and partially reconstructed for selected patterns (or regions processed into a block containing the patterns), may be any other data layer number that is different from the normal OPC data. layer number), so that partial OPC may be performed only on patterns corresponding to the layer number when subsequent partial OPC is performed again.

After partial OPC is again selectively performed only on the selected patterns (or regions), partial OPC verification is performed again on only the patterns (213). Determine (214) whether the result according to the partial OPC and partial verification for this selected pattern falls within the specified acceptance range, and repeatedly generate error markers 211 to partial until controlled to fall within the specified acceptance range. OPC verification 213 steps are repeated. As a result, when all the patterns satisfy the given acceptance range, mask fabrication is performed (209).

As described above, the embodiment of the present invention selectively selects only patterns in which an error has occurred, and re-performs OPC and verification only on the patterns, thereby correcting the OPC error in a relatively small area of the related art. The time consumed when performing re-OPC and revalidation can be greatly reduced.

As mentioned above, although this invention was demonstrated in detail through the specific Example, this invention is not limited to this, It is clear that the deformation | transformation and improvement are possible by the person of ordinary skill in the art within the technical idea of this invention.

According to the present invention described above, in order to correct the pattern distortion caused by the optical proximity effect (OPE), only OPC error patterns obtained through OPC verification are selectively selected, and OPC is selectively recovered only for the selected patterns. By doing so, the time required for manufacturing the mask can be effectively reduced. Accordingly, it is possible to greatly reduce the time required for the development and production of semiconductor devices.

Claims (5)

Manufacturing a test mask of target patterns; Transferring the patterns onto a wafer using the test mask; Measuring line width (CD) data of the patterns; Generating a model calibration and optical proximity effect correction (OPC) recipe using the linewidth data; Performing first optical proximity effect correction (OPC) on the entire mask area using the model and recipe; First verifying the result of the first optical proximity effect correction (OPC); Selectively performing second optical proximity effect correction (OPC) and second verification only on the pattern in which an error occurred in the first verification; And And manufacturing a mask using the optical proximity effect correction (OPC) verified result. Manufacturing a test mask of target patterns; Transferring the patterns onto a wafer using a plurality of exposure conditions using the test mask; Measuring linewidth data of the patterns associated with the exposure conditions; A model calibration step of generating a plurality of models associated with the exposure conditions using the linewidth data; Generating an optical proximity effect correction (OPC) recipe for the models; Performing first optical proximity effect correction (OPC) using the model and recipe; First verifying using the models for the results of the first optical proximity effect correction (OPC); Selectively performing second optical proximity effect correction (OPC) on the patterns in which an error occurred in the first verification using the recipes; Selectively performing secondary verification using the associated model and recipe for the results of the second optical proximity effect correction (OPC); And And manufacturing a mask using the optical proximity effect correction (OPC) verified result. The method of claim 2, Generating an error marker for the patterns in which an error occurs during the optical proximity effect correction (OPC) verification; And And backing up the error result to a differentiated data layer number such that the second optical proximity effect correction (OPC) is performed only for the pattern in which the error occurred. OPE) correction method. The method of claim 2, And the second optical proximity effect correction (OPC) and the second verification are performed only on the selected region by selecting the region including the error pattern. The method of claim 2, And the second optical proximity effect correction (OPC) and the second verification step are repeated until the verification result of the patterns is determined within a set acceptance range.

Images