Method of improving process window of optical proximity correction model

Abstract

This invention provides a method for improving the process window of an optical proximity correction model. It provides multiple sets of substrates with different thicknesses, each with a film layer of different thickness and material. Data from post-development and post-etching inspections are collected from each set of substrates. A first compensation value for photolithography is obtained using the post-development inspection data, and a second compensation value is obtained based on the post-etching inspection data. The first and second compensation values ​​are fed back to the optical proximity correction, causing the process windows of different patterns in different regions of the same lithography layer on different substrates to tend to be consistent. This invention performs optical proximity correction on different substrates and different design patterns, enabling all patterns to have a sufficient common process window.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a method for improving the process window of an optical proximity effect correction model. Background Technology

[0002] Currently, for patterns with small lithography process windows, once the lithography machine, lithography material, and OPC (Optical Proximity Correction) model are determined, the model is usually optimized. This includes monitoring patterns with small lithography process windows, considering the impact of etching on the model, and the impact of external factors on the model, etc.

[0003] Different OPC model optimizations require the collection and adjustment of different graphs and data. For graphs with small process windows, PWOPC is generally used for verification; for the impact of etching on OPC, etching deviation values ​​are usually collected for compensation; when the front substrate is different, the substrate influence parameters need to be imported into the OPC model to improve the model accuracy, etc.

[0004] When different regions of the same layer have different substrates, some patterns with smaller process windows are prone to defocusing due to levelness factors, affecting the overall process window.

[0005] Specifically, Figure 1 This is a schematic diagram showing the horizontality of two shots at different locations on the same photomask after exposure at a certain photolithography layer for a certain product. It can be seen that the horizontality varies in different areas within the same shot, reflecting local substrate differences. The horizontality of shots at different locations within the wafer may also differ, which is due to substrate differences at the wafer level. Figure 2 These are schematic diagrams of different substrates. When the type or thickness of the substrate is different, the OPC model may be affected. Therefore, it is necessary to classify the substrates differently, provide different correction parameters for different substrates, and adjust the common process window of all patterns.

[0006] Figure 3 These are the through pitch curves for different patterns at a certain photolithography layer in a certain product segment, under different substrates. It can be seen that different substrates and designs exhibit significant CD variation (critical dimension variation), making the common process window easily affected. Figure 4 This refers to the expected curve representing the key dimensions of the graphic.

[0007] Figure 5 and Figure 6 Simulation results of a certain photolithography layer in a certain product segment show that the photolithography process parameters (reflectivity, etc.) vary inconsistently under different substrate conditions, so the process window for different patterns may be affected.

[0008] To address the aforementioned issues, a novel method is needed to improve the process window of the optical proximity effect correction model. Summary of the Invention

[0009] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a method for improving the process window of the optical proximity effect correction model, which solves the problem in the prior art that when different regions of the same layer have different substrates, some smaller process windows are prone to defocusing due to levelness factors, affecting the overall process window.

[0010] To achieve the above and other related objectives, the present invention provides a method for improving the process window of an optical proximity effect correction model, comprising:

[0011] Step 1: Provide multiple sets of substrates with different thicknesses, and form films of different thicknesses and materials on each set of substrates;

[0012] Step 2: Collect data on post-development and post-etching inspections on each set of substrates;

[0013] Step 3: Obtain the first compensation value for photolithography using the data detected after development, and obtain the second compensation value for photolithography based on the data detected after etching;

[0014] Step 4: Use the first and second compensation values ​​to feed back to the optical proximity correction, so that the patterned process windows in different regions of the same lithography layer on different substrates tend to be consistent.

[0015] Preferably, the substrate in step one comprises a bulk semiconductor substrate or a silicon-on-insulator (SOI) substrate.

[0016] Preferably, in step two, simulation software is used to collect data on post-development and post-etching inspections on each group of substrates.

[0017] Preferably, the film layer in step one includes at least one of a photoresist layer, a spin-coated carbon hard mask layer, an oxide layer, and a nitride layer.

[0018] Preferably, the method for collecting post-development and post-etching detection data on each set of substrates in step two includes: forming a photoresist layer on each set of substrates and the film layer thereon; photolithographically opening the photoresist layer to define an etching pattern; collecting the post-development detection data using the opened photoresist layer; transferring the etching pattern to the film layer using etching; and collecting the post-etching detection data using the etched film layer.

[0019] Preferably, in step two, scanning electron microscopy is used to collect data from the post-development detection and the post-etching detection.

[0020] Preferably, the first and second compensation values ​​in step four are used for optical proximity correction of the PWOPC model.

[0021] Preferably, the graphic in step four is a line graphic or a two-dimensional graphic.

[0022] As described above, the method of improving the process window of the optical proximity effect correction model of the present invention has the following beneficial effects:

[0023] This invention performs optical proximity correction on different substrates and different design patterns, which can enable all patterns to have a sufficient common process window. Attached Figure Description

[0024] Figure 1 This is a schematic diagram showing the horizontality of two shots at different positions after exposure using the same photomask in the prior art.

[0025] Figure 2 The diagram shows post-development measurements on different substrates in the prior art.

[0026] Figure 3 This is a schematic diagram showing the variation curves of different patterns (through pitch) at a certain photolithography layer in the prior art under different substrate conditions;

[0027] Figure 4 This is a schematic diagram showing the expected changes of different patterns (through pitch) at a certain photolithography layer in the prior art under different substrates;

[0028] Figure 5 and Figure 6 The diagram shows simulation results of different substrates at a certain photolithography level in a certain section of a product in the prior art.

[0029] Figure 7 The diagram shows a method for improving the process window of the optical proximity effect correction model according to the present invention. Detailed Implementation

[0030] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0031] Please see Figure 7 This invention provides a method for improving the process window of an optical proximity effect correction model, comprising:

[0032] Step 1: Provide multiple sets of substrates with different thicknesses. Here, you can provide the wafer to be tested or use software simulation to generate substrates with different thicknesses. Each set of substrates has a film layer of different thickness and material. When the type or thickness of the substrate is different, the OPC model may be affected. Therefore, it is necessary to classify the substrates differently, provide different correction parameters for different substrates, and adjust the common process window of all patterns.

[0033] In one alternative embodiment, the substrate in step one comprises a bulk semiconductor substrate or a silicon-on-insulator (SOI) substrate. The SOI substrate includes an insulating layer beneath a thin semiconductor layer serving as the active layer. The semiconductor in the active layer and the bulk semiconductor typically comprise the crystalline semiconductor material silicon, but may also include one or more other semiconductor materials, such as germanium, silicon-germanium alloys, compound semiconductors (e.g., GaAs, AlAs, InAs, GaN, AlN, etc.) or alloys thereof (e.g., GaxAl1-xAs, GaxAl1-xN, InxGa1-xAs, etc.), oxide semiconductors (e.g., ZnO, SnO2, TiO2, Ga2O3, etc.), or combinations thereof. The semiconductor material may be doped or undoped. Other substrates that may be used include multilayer substrates, gradient substrates, or mixed-orientation substrates.

[0034] In one optional embodiment, the film layer in step one includes at least one of a photoresist layer, a spin-coated carbon hard mask layer, an oxide layer, and a nitride layer. The material of the oxide layer is usually silicon dioxide, and the material of the nitride layer is usually silicon nitride. The film layer here can also be other materials well known to those skilled in the art.

[0035] Step 2: Collect post-development and post-etching inspection data for each set of substrates. By collecting post-development and post-etching inspection data for different substrates and patterns with different designs, the optimal conditions and process windows for different patterns can be obtained. For patterns with small process windows, appropriate adjustments to OPC (Optical Proximity Correction) can increase the common process window.

[0036] In one alternative implementation, step two involves using simulation software to collect data on post-development and post-etching inspections of each substrate group.

[0037] In one optional implementation, the method for collecting post-development detection and post-etching detection data on each set of substrates in step two includes: forming a photoresist layer on each set of substrates and the film layer thereon; photolithographically opening the photoresist layer to define the etching pattern; collecting post-development detection data using the opened photoresist layer; transferring the etching pattern to the film layer using etching; and collecting post-etching detection data using the etched film layer.

[0038] In one alternative implementation, in step two, scanning electron microscopy is used to collect data from post-development and post-etching detection.

[0039] Step 3: Obtain the first compensation value for photolithography using the data detected after development, and obtain the second compensation value for photolithography based on the data detected after etching;

[0040] Step 4: Use the first and second compensation values ​​to feed back to optical proximity correction, so that the patterned process windows in different areas of the same lithography layer on different substrates tend to be consistent.

[0041] In an alternative implementation, the first and second compensation values ​​in step four are used for optical proximity correction of the PWOPC model.

[0042] In one alternative implementation, the graphics in step four are line graphics and two-dimensional graphics.

[0043] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0044] In summary, this invention performs optical proximity correction on different substrates and different design patterns, enabling all patterns to have sufficient common process windows. Therefore, this invention effectively overcomes the various shortcomings of existing technologies and has high industrial applicability.

[0045] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for improving the process window of an optical proximity effect correction model, characterized in that, At least including: Step 1: Provide multiple sets of substrates with different thicknesses, and form films of different thicknesses and materials on each set of substrates; Step 2: Collect post-development and post-etching detection data on each set of substrates. The method for collecting post-development and post-etching detection data on each set of substrates includes: forming a photoresist layer on each set of substrates and the film layer thereon; photolithographically opening the photoresist layer to define an etching pattern; collecting the post-development detection data using the opened photoresist layer; transferring the etching pattern to the film layer using etching; and collecting the post-etching detection data using the etched film layer. Step 3: Obtain a first compensation value for photolithography using the data detected after development, and obtain a second compensation value for photolithography based on the data detected after etching; Step 4: Use the first and second compensation values ​​to feed back to the optical proximity correction, so that the patterned process windows in different regions of the same lithography layer on different substrates tend to be consistent.

2. The method for improving the process window of the optical proximity effect correction model according to claim 1, characterized in that: The substrate in step one includes a bulk semiconductor substrate or a silicon-on-insulator (SOI) substrate.

3. The method for improving the process window of the optical proximity effect correction model according to claim 1, characterized in that: The film layer in step one includes at least one of the following: a photoresist layer, a spin-coated carbon hard mask layer, an oxide layer, and a nitride layer.

4. The method for improving the process window of the optical proximity effect correction model according to claim 1, characterized in that: In step two, simulation software is used to collect data on the post-development and post-etching inspections of each set of substrates.

5. The method for improving the process window of the optical proximity effect correction model according to claim 1, characterized in that: In step two, scanning electron microscopy is used to collect data from the post-development detection and the post-etching detection.

6. The method for improving the process window of the optical proximity effect correction model according to claim 1, characterized in that: The first and second compensation values ​​in step four are used for optical proximity correction of the PWOPC model.

7. The method for improving the process window of the optical proximity effect correction model according to claim 1, characterized in that: The graphics mentioned in step four are line graphics and two-dimensional graphics.

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