TWI828075B - Inspection method of patterned photoresist layer and optimization method of lithography process - Google Patents

Abstract

An inspection method of a patterned photoresist layer including the following steps is provided. A lithography process is performed to form a patterned photoresist layer. A photoresist profile inspection process is performed. The photoresist profile inspection process includes the following steps. A first inspection process is performed on a profile of the patterned photoresist layer by an inspection apparatus. After the first inspection process is performed, at least one advanced inspection process is performed. The advanced inspection process includes the following steps. A global exposure process is performed on the patterned photoresist layer. After the global exposure process is performed, a development process is performed on the patterned photoresist layer to remove a portion of the patterned photoresist layer from a top of the patterned photoresist layer. After the portion of the patterned photoresist layer is removed, a second inspection process is performed on the profile of the patterned photoresist layer by the inspection apparatus.

Description

Inspection method of patterned photoresist layer and optimization method of lithography process

The present invention relates to a semiconductor manufacturing process, and in particular, to an inspection method of a patterned photoresist layer and an optimization method of a lithography process.

Currently, after a patterned photoresist layer is formed through a photolithography process, an inspection machine is used to check whether the outline of the patterned photoresist layer is abnormal. However, due to limitations in the capabilities of the inspection machine, when the patterned photoresist layer has a pattern with a high aspect ratio, it is difficult for the inspection machine to confirm the bottom contour of the patterned photoresist layer. As a result, when the patterned photoresist layer has a pattern with a high aspect ratio, it is difficult to use an inspection machine to check whether the outline of the patterned photoresist layer is abnormal.

The present invention provides a method for inspecting a patterned photoresist layer, which can effectively inspect whether the outline of the patterned photoresist layer is abnormal.

The present invention provides a method for optimizing the lithography process, which can find the optimized process parameters of the lithography process.

The invention proposes an inspection method for a patterned photoresist layer, which includes the following steps. A photolithography process is performed to form a patterned photoresist layer. Perform photoresist profile inspection process. The photoresist profile inspection process includes the following steps. A first inspection process is performed on the outline of the patterned photoresist layer using an inspection machine. After performing the first inspection process, at least one advanced inspection process is performed. The advanced inspection process includes the following steps. A comprehensive exposure process is performed on the patterned photoresist layer. After the overall exposure process, the patterned photoresist layer is subjected to a development process to remove part of the patterned photoresist layer from the top of the patterned photoresist layer. After removing part of the patterned photoresist layer, a second inspection process is performed on the outline of the patterned photoresist layer using an inspection machine.

According to an embodiment of the present invention, in the above inspection method of the patterned photoresist layer, the material of the patterned photoresist layer may be a positive photoresist material.

According to an embodiment of the present invention, the above method for inspecting the patterned photoresist layer further includes performing the following steps. After performing the overall exposure process and before performing the development process, the patterned photoresist layer is subjected to a baking process.

According to an embodiment of the present invention, in the above inspection method of the patterned photoresist layer, a blank mask may be used in the overall exposure process.

According to an embodiment of the present invention, in the above inspection method of the patterned photoresist layer, a photomask is not used in the overall exposure process.

According to an embodiment of the present invention, in the above inspection method of the patterned photoresist layer, the inspection machine may be a scanning electron microscope (SEM) or an optical microscope (optical microscope).

The present invention proposes an optimization method for a photolithography process, which includes the following steps. A photolithography process is performed to form a patterned photoresist layer. Perform photoresist profile inspection process. The photoresist profile inspection process includes the following steps. A first inspection process is performed on the outline of the patterned photoresist layer using an inspection machine. After performing the first inspection process, at least one advanced inspection process is performed. The advanced inspection process includes the following steps. A comprehensive exposure process is performed on the patterned photoresist layer. After the overall exposure process, the patterned photoresist layer is subjected to a development process to remove part of the patterned photoresist layer from the top of the patterned photoresist layer. After removing part of the patterned photoresist layer, a second inspection process is performed on the outline of the patterned photoresist layer using an inspection machine. Perform at least one lithography parameter optimization process. The lithography parameter optimization process includes the following steps. After removing the remaining patterned photoresist layer, the process parameters of the lithography process are adjusted according to the inspection results of the photoresist profile inspection process. The lithography process is performed using the adjusted process parameters of the lithography process, and then the photoresist profile inspection process is performed.

According to an embodiment of the present invention, in the optimization method of the lithography process, the material of the patterned photoresist layer may be a positive photoresist material.

According to an embodiment of the present invention, the above lithography process optimization method may further include the following steps. After performing the overall exposure process and before performing the development process, the patterned photoresist layer is subjected to a baking process.

According to an embodiment of the present invention, in the above-mentioned optimization method of the lithography process, the inspection machine may be a scanning electron microscope or an optical microscope.

Based on the above, in the inspection method of the patterned photoresist layer proposed by the present invention, after performing the first inspection process, at least one advanced inspection process is performed. In addition, in the advanced inspection process, part of the patterned photoresist layer will be removed from the top of the patterned photoresist layer through a comprehensive exposure process and a development process, and then a second inspection process will be performed on the outline of the patterned photoresist layer. . That is to say, the advanced inspection process can first reduce the aspect ratio of the pattern of the patterned photoresist layer, and then perform the second inspection process on the outline of the patterned photoresist layer, thereby effectively confirming the pattern of the patterned photoresist layer. Bottom outline. Therefore, the inspection method of the patterned photoresist layer proposed by the present invention can effectively check whether the outline of the patterned photoresist layer is abnormal (for example, the bottom of the pattern is partially hollowed out or the critical dimensions do not meet regulations, etc.).

In addition, in the optimization method of the lithography process proposed by the present invention, when it is found that the outline of the patterned photoresist layer is abnormal from the inspection results of the photoresist profile inspection process, by performing at least one lithography parameter To optimize the process, the lithography process and photoresist profile inspection process can be performed again after re-adjusting the process parameters of the lithography process. In this way, when it is found from the inspection results of the photoresist profile inspection process that the patterned photoresist layer has a normal profile, the process parameters of the lithography process used at this time are the optimized process parameters. Therefore, the optimization method of the lithography process proposed by the present invention can find the optimal process parameters of the lithography process.

In order to make the above-mentioned features and advantages of the present invention more obvious and easy to understand, embodiments are given below and described in detail with reference to the accompanying drawings.

Examples are listed below and described in detail with reference to the drawings. However, the provided examples are not intended to limit the scope of the present invention. To facilitate understanding, the same components will be identified with the same symbols in the following description. In addition, the drawings are for illustrative purposes only and are not drawn to original size. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

FIG. 1 is a flow chart of an inspection method for a patterned photoresist layer according to some embodiments of the present invention. Figure 2A is a top view of a patterned photoresist layer according to some embodiments of the present invention. FIG. 2B is a top view after removing part of the patterned photoresist layer in FIG. 2A . Figure 3 is a cross-sectional view along the line I-I' and the line II-II' in Figure 2A according to some embodiments of the present invention.

Referring to FIG. 1 , step S100 is performed to perform a photolithography process to form a patterned photoresist layer. In this embodiment, the material of the patterned photoresist layer may be a positive photoresist material. For example, as shown in FIG. 2A and FIG. 3 , the patterned photoresist layer PR1 can be formed on the material layer 100 through a photolithography process. In this embodiment, as shown in FIG. 2A , the patterned photoresist layer PR1 may be in a grid shape and may have an opening OP exposing the substrate 100 , but the invention is not limited thereto. A person with ordinary skill in the art can determine the shape of the patterned photoresist layer PR1 according to requirements. For example, in other embodiments, the patterned photoresist layer PR1 may be in a strip shape. In some embodiments, the material layer 100 may be a material layer to be patterned, such as a substrate (eg, a semiconductor substrate), a conductive layer, a dielectric layer, a semiconductor layer, or a combination thereof, but the invention is not limited thereto. In some embodiments, the photolithography process may include photoresist coating, exposure and development processes. In this embodiment, the photoresist material used in the photoresist coating process may be a positive photoresist material. In some embodiments, the lithography process may further include a baking process, such as a pre-exposure baking process, a post-exposure baking process, or a combination thereof.

In addition, the patterned photoresist layer formed by the photolithography process can be a "normal patterned photoresist layer" or an "abnormal patterned photoresist layer". In this embodiment, "normal patterned photoresist layer" means that the patterned photoresist layer has a normal profile that meets the requirements, and "abnormal patterned photoresist layer" means that the patterned photoresist layer does not have a profile that meets the requirements. The outline of the patterned photoresist layer (for example, the bottom of the pattern of the patterned photoresist layer is partially hollowed out or the critical dimensions do not meet the regulations, etc.).

In this embodiment, the patterned photoresist layer PR1 is described as an abnormal patterned photoresist layer, but the invention is not limited thereto. For example, as shown in FIG. 3 , the patterned photoresist layer PR1 may include an upper part P1 and a lower part P2, and the upper part P1 is located on the lower part P2. In this embodiment, there is no abnormality in the upper part P1 of the patterned photoresist layer PR1, but the invention is not limited thereto. In this embodiment, an abnormality occurs in the lower part P2 of the patterned photoresist layer PR1. For example, the lower part P2 of the patterned photoresist layer PR1 is partially hollowed out to form a hole V (that is, the pattern bottom of the patterned photoresist layer PR1 is hollowed out. It is partially hollowed out to form a hole V), but the invention is not limited thereto. In other embodiments, the patterned photoresist layer PR1 can also be a normal patterned photoresist layer.

Next, please refer to FIG. 1 to perform step S200 to perform a photoresist profile inspection process. The photoresist profile inspection process in step S200 includes the following steps. First, step S202 is performed to perform a first inspection process on the outline of the patterned photoresist layer using an inspection machine. For example, depending on the capability of the inspection machine, the first inspection process can be used to inspect whether the outline of at least a part of the patterned photoresist layer PR1 in FIG. 3 (eg, at least a part of the upper part P1) is abnormal. However, the present invention does not use This is the limit. In some embodiments, the detection instrument may be a scanning electron microscope or an optical microscope. In some embodiments, the scanning electron microscope may be a critical dimension-scanning electron microscope (CD-SEM) or a tilt-scanning electron microscope (tilt-SEM).

Then, step S204 is performed, and after performing the first inspection process, at least one advanced inspection process is performed. The advanced inspection process of step S204 includes the following steps. First, step S206 is performed to perform an overall exposure process on the patterned photoresist layer. The full exposure process can illuminate the entire top surface of the patterned photoresist layer with an exposure light source. In some embodiments, a blank mask may be used in the full exposure process. The blank mask may be a mask without a pattern. In some embodiments, the blank mask may be a transparent mask, such as a glass mask. In some embodiments, the full exposure process does not use a photomask. In some embodiments, the focal point of the blanket exposure process may be located near the top of the patterned photoresist layer. For example, the focus of the overall exposure process may be located in the upper part P1 of the patterned photoresist layer PR1 in FIG. 3 .

Next, step S208 is performed. After performing the overall exposure process, the patterned photoresist layer is subjected to a development process to remove part of the patterned photoresist layer from the top of the patterned photoresist layer. Thereby, the aspect ratio of the pattern of the patterned photoresist layer can be reduced. In some embodiments, since the focal point of the full exposure process may be located close to the top of the patterned photoresist layer, a portion of the patterned photoresist layer may be removed from the top of the patterned photoresist layer. For example, the development process may remove at least a portion of the upper portion P1 of the patterned photoresist layer PR1 in FIG. 3 .

In some embodiments, after performing the overall exposure process (step S206) and before performing the development process (step S208), the patterned photoresist layer may be baked. In other embodiments, after performing the overall exposure process (step S206) and before performing the development process (step S208), the patterned photoresist layer may not be baked.

Subsequently, step S210 is performed. After removing part of the patterned photoresist layer, a second inspection process is performed on the outline of the patterned photoresist layer using an inspection machine. The second inspection process can be used to confirm the bottom profile of the patterned photoresist layer, and therefore can be used to check whether the profile of the patterned photoresist layer is abnormal. In some embodiments, the detection instrument may be a scanning electron microscope or an optical microscope. In some embodiments, the scanning electron microscope may be a critical dimension-scanning electron microscope or a tilt-scanning electron microscope.

In addition, if the first second inspection process cannot effectively confirm the bottom contour of the patterned photoresist layer, the advanced inspection process of step S204 can be repeated. Therefore, the aspect ratio of the patterned photoresist layer can be further reduced, so that the inspection machine can effectively confirm the bottom profile of the patterned photoresist layer, thereby effectively checking whether the profile of the patterned photoresist layer is abnormal. . For example, as shown in FIG. 2B , the upper portion P1 of the patterned photoresist layer PR1 in FIG. 3 can be removed by performing at least one advanced inspection process (step S204 ) to expose the upper portion P1 of the patterned photoresist layer PR1 . The lower part P2, but the present invention is not limited to this. Therefore, the inspection machine can effectively confirm the bottom contour of the patterned photoresist layer PR1, thereby effectively checking whether the contour of the patterned photoresist layer PR1 is abnormal. In this embodiment, although the entire upper portion P1 of the patterned photoresist layer PR1 in FIG. 3 is removed as an example, the present invention is not limited to this. As long as part of the patterned photoresist layer PR1 is removed from the top of the patterned photoresist layer PR1 and the profile of the patterned photoresist layer PR1 can be effectively checked to see if it is abnormal, it falls within the scope of the present invention.

Based on the above embodiments, it can be known that in the above inspection method of the patterned photoresist layer, after performing the first inspection process, at least one advanced inspection process is performed. In addition, in the advanced inspection process, part of the patterned photoresist layer will be removed from the top of the patterned photoresist layer through a comprehensive exposure process and a development process, and then a second inspection process will be performed on the outline of the patterned photoresist layer. . That is to say, the advanced inspection process can first reduce the aspect ratio of the pattern of the patterned photoresist layer, and then perform the second inspection process on the outline of the patterned photoresist layer, thereby effectively confirming the pattern of the patterned photoresist layer. Bottom outline. Therefore, the inspection method of the patterned photoresist layer in the above embodiment can effectively check whether the outline of the patterned photoresist layer is abnormal (for example, the bottom of the pattern is partially hollowed out or the critical dimensions do not meet regulations, etc.).

Figure 4 is a flow chart of a method for optimizing a lithography process according to some embodiments of the present invention. Figure 5 is a cross-sectional view along the line I-I' and the line II-II' in Figure 2A according to some embodiments of the present invention.

Please refer to FIGS. 1 and 4 . Compared with the optimization method of the lithography process of FIG. 1 , the optimization method of the lithography process of FIG. 4 further includes the following steps. Go to step S300 to perform at least one lithography parameter optimization process. The lithography parameter optimization process of step S300 includes the following steps. First, step S302 is performed. After removing the remaining patterned photoresist layer, the process parameters of the lithography process are adjusted according to the inspection results of the photoresist profile inspection process. That is, before performing step S302, the remaining patterned photoresist layer after performing step S204 (eg, the lower part P2 of the patterned photoresist layer PR1 in FIG. 2B) is removed. In step S302, the process parameters of the lithography process to be adjusted may include the focus of the exposure process (including the focus of multi-focus exposure), the exposure dose of the exposure process, the numerical aperture, the wavelength of the light source, the illumination system, or a combination thereof.

Next, step S304 is performed, the lithography process is performed using the adjusted process parameters of the lithography process (step S100), and then the photoresist profile inspection process is performed (step S200). If it is found from the inspection results of the photoresist profile inspection process that the patterned photoresist layer has a normal profile (for example, compared to the patterned photoresist layer PR1 of Figure 3, the patterned photoresist layer PR2 of Figure 5 has a normal profile) , then the process parameters of the lithography process used at this time are the optimized process parameters.

In addition, if the first lithography parameter optimization process has not obtained the optimal process parameters of the lithography process, the lithography parameter optimization process of step S300 can be repeated until the optimal lithography process parameters are found. process parameters.

In addition, the same steps in the optimization method of the lithography process in FIG. 4 and the inspection method of the patterned photoresist layer in FIG. 1 are represented by the same symbols and will not be described again.

Based on the above embodiments, it can be seen that in the above optimization method of the lithography process, when it is found that the outline of the patterned photoresist layer is abnormal according to the inspection results of the photoresist profile inspection process, by performing at least one lithography parameter To optimize the process, the lithography process and photoresist profile inspection process can be performed again after re-adjusting the process parameters of the lithography process. In this way, when it is found from the inspection results of the photoresist profile inspection process that the patterned photoresist layer has a normal profile, the process parameters of the lithography process used at this time are the optimized process parameters. Therefore, the optimization method of the lithography process in the above embodiment can find the optimal process parameters of the lithography process. In addition, the above-mentioned optimization method of the lithography process can reduce the amount of wafers used to check the photoresist profile by slicing as in the traditional method, thereby accelerating the development time of process optimization.

In summary, in the inspection method of the patterned photoresist layer in the above embodiment, the aspect ratio of the pattern of the patterned photoresist layer can be reduced through an advanced inspection process, and then the outline of the patterned photoresist layer can be A second inspection process is performed, whereby the bottom contour of the patterned photoresist layer can be effectively confirmed. Therefore, the inspection method of the patterned photoresist layer in the above embodiment can effectively check whether the profile of the patterned photoresist layer is abnormal. In addition, in the optimization method of the lithography process in the above embodiment, when it is found that the outline of the patterned photoresist layer is abnormal due to the inspection results of the photoresist profile inspection process, the lithography parameters are optimized by performing at least one To optimize the process, after re-adjusting the process parameters of the lithography process, the lithography process and the photoresist profile inspection process can be performed again, so as to find out the optimized process parameters of the lithography process.

Although the present invention has been disclosed above through embodiments, they are not intended to limit the present invention. Anyone with ordinary knowledge in the technical field may make some modifications and modifications without departing from the spirit and scope of the present invention. Therefore, The protection scope of the present invention shall be determined by the appended patent application scope.

100:Base OP: Open your mouth P1: upper part P2: lower part PR1, PR2: patterned photoresist layer S100, S200, S202, S204, S206, S208, S210, S300, S302, S304: Steps V: hole

FIG. 1 is a flow chart of an inspection method for a patterned photoresist layer according to some embodiments of the present invention. Figure 2A is a top view of a patterned photoresist layer according to some embodiments of the present invention. FIG. 2B is a top view after removing part of the patterned photoresist layer in FIG. 2A . Figure 3 is a cross-sectional view along the line I-I' and the line II-II' in Figure 2A according to some embodiments of the present invention. Figure 4 is a flow chart of a method for optimizing a lithography process according to some embodiments of the present invention. Figure 5 is a cross-sectional view along the line I-I' and the line II-II' in Figure 2A according to some embodiments of the present invention.

S100, S200, S202, S204, S206, S208, S210: steps

Claims (10)

An inspection method for a patterned photoresist layer, including: performing a photolithography process to form a patterned photoresist layer; and performing a photoresist profile inspection process, wherein the photoresist profile inspection process includes: using an inspection machine to inspect the The profile of the patterned photoresist layer is subjected to a first inspection process; and after the first inspection process is performed, at least one advanced inspection process is performed, wherein the advanced inspection process includes: inspecting the patterned photoresist layer Perform a full-scale exposure process; after performing the full-scale exposure process, perform a development process on the patterned photoresist layer to remove part of the patterned photoresist layer from the top of the patterned photoresist layer, and reducing the aspect ratio of the patterned photoresist layer; and after removing part of the patterned photoresist layer, using the inspection machine to measure the patterned photoresist layer after reducing the aspect ratio. The profile is subjected to a second inspection process, wherein the second inspection process includes confirming the bottom profile of the patterned photoresist layer after reducing the aspect ratio. The inspection method for a patterned photoresist layer as claimed in claim 1, wherein the material of the patterned photoresist layer includes a positive photoresist material. The inspection method of the patterned photoresist layer as described in claim 1 further includes performing a baking process on the patterned photoresist layer after performing the full-scale exposure process and before performing the development process. The inspection method of the patterned photoresist layer according to claim 1, wherein the full-scale exposure process uses a blank photomask. The inspection method of the patterned photoresist layer as claimed in claim 1, wherein the full-scale exposure process does not use a photomask. The inspection method of the patterned photoresist layer according to claim 1, wherein the inspection machine includes a scanning electron microscope or an optical microscope. An optimization method for a photolithography process, including: performing a photolithography process to form a patterned photoresist layer; and performing a photoresist profile inspection process, wherein the photoresist profile inspection process includes: using a detection machine to inspect the The outline of the patterned photoresist layer is subjected to a first inspection process; and after the first inspection process is performed, at least one advanced inspection process is performed, wherein the advanced inspection process includes: performing an inspection process on the patterned photoresist layer. A comprehensive exposure process; after performing the comprehensive exposure process, a development process is performed on the patterned photoresist layer to remove part of the patterned photoresist layer from the top of the patterned photoresist layer, and Reduce the aspect ratio of the patterned photoresist layer; and after removing part of the patterned photoresist layer, use the inspection machine to measure the profile of the patterned photoresist layer after reducing the aspect ratio. Performing a second inspection process, wherein the second inspection process includes confirming the bottom profile of the patterned photoresist layer after reducing the aspect ratio; and Performing at least one lithography parameter optimization process, wherein the lithography parameter optimization process includes: after removing the remaining patterned photoresist layer, adjusting according to the inspection results of the photoresist profile inspection process. The process parameters of the lithography process; and using the adjusted process parameters of the lithography process to perform the lithography process, and then perform the photoresist profile inspection process. The method for optimizing the photolithography process of claim 7, wherein the material of the patterned photoresist layer includes a positive photoresist material. The method for optimizing the photolithography process of claim 7 further includes performing a baking process on the patterned photoresist layer after performing the full-scale exposure process and before performing the development process. The method for optimizing the lithography process as claimed in claim 7, wherein the inspection machine includes a scanning electron microscope or an optical microscope.

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