This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2020-131828, filed Aug. 3, 2020, the entire contents of which are incorporated herein by reference.
Embodiments described herein relate generally to an original plate manufacturing method, a drawing data creation method, and a pattern defect repairing method.
One of the processes involved in manufacturing a semiconductor device is a process of transferring a predetermined pattern to a substrate. Examples of a technique used in this process include a photolithography technique and an imprinting technique. With the photolithography technique, a pattern drawn on an original plate called a photomask is transferred to a photosensitive polymer material on a substrate to form an etching mask. With the imprinting technique, an original plate called a template having a pattern thereon is pressed against a resist on a substrate to form an etching mask. After patterning with these techniques, an underlying layer is etched using the etching mask, and the pattern is transferred to the substrate.
Due to high integration of semiconductor devices, patterns are becoming finer (smaller minimum features), such that it becomes more difficult not only to manufacture semiconductor devices themselves but also to manufacture the original plates used in manufacturing semiconductor devices.
Embodiments provide an original plate manufacturing method, a drawing data generation method, and a pattern defect repairing method capable of repairing pattern defects which may be generated on an original plate when fine patterns are formed on the original plate.
In general, according to one embodiment, an original plate manufacturing method includes preparing first design data and second design data from a predetermined pattern to be formed on a target object. The first design data corresponds to a first design pattern, and the second design data corresponds to a second design pattern. The first and second design patterns are complementary portions of the predetermined pattern. The first design pattern is then formed on the target object based on the first design data. An inspection is performed on the target object on which the first design pattern has been formed. Third design data based on a result of the inspection is generated. The second design data is adjusted based on the third design data to generate corrected second design data. The target object on which the first design pattern has already been formed is then patterned based on the corrected second design data.
Hereinafter, non-limiting example embodiments of the present disclosure will be described with reference to the accompanying drawings. In the accompanying drawings, like reference numerals denote like elements or components, and descriptions of the same elements will be omitted. In addition, the drawings are not intended to represent relative dimensional ratios between members and components, or thicknesses of various layers, and thus, thickness or sizes of actual components and the like should be determined by those skilled in the art according to the following non-limiting embodiments.
An original plate manufacturing method according to a first embodiment will be described with reference to
In the original plate manufacturing method according to the first embodiment, a starting material 10 of the template is prepared as shown in
The starting material 10 is provided with alignment marks 16. The alignment mark 16 is implemented as an opening formed in the metal film 14 and a recess in the quartz substrate 12 formed corresponding to the opening. The alignment mark 16 is used when drawing a design pattern on the quartz substrate 12 during the manufacturing of the template. The alignment mark 16 may also be subsequently used to position the finished template relative to a substrate to be imprinted when the finished template is pressed against the resist film. In the following description, although two alignment marks 16 are particularly depicted in the drawings, it should be understood that the example includes four alignment marks 16 arranged at each of the four corners of the quartz substrate 12. Further, the starting material 10 may have, for example, a resin substrate instead of the quartz substrate 12. Like the quartz substrate 12, the resin substrate may be formed of a material that transmits ultraviolet light. Furthermore, the metal film 14 may be formed of, but is not limited to, chromium (Cr). Furthermore, an organic hard mask, such as diamond-like carbon, may be used instead of the metal film 14.
Next, as shown in
The EB drawing device includes a control unit including, for example, a central processing unit (CPU), and the control unit controls the electron gun, the electron lens, and the electron beam deflection controlling system based on design data prepared in advance. In the present embodiment, the design data is the data used for drawing the pattern that the finished template is to have (hereinafter, referred to as a template pattern). Further, the design data includes first design data corresponding to the first design pattern CP1 and second design data corresponding to a second design pattern CP2 to be described later. The first design data includes information on a shape and/or line width of the first design pattern CP1, information on an electron beam intensity (irradiation dose), and the like, and the second design data also includes information on a shape and/or line width of the second design pattern CP2, information on an electron beam intensity (irradiation dose), and the like.
The first design pattern CP1 and the second design pattern CP2 each have a pitch that is twice the pitch of the template pattern (pitch in a repetitive line-and-space pattern is equal to the sum of a line width and a space width). When these two design patterns CP1 and CP2 are combined, a finer template pattern is achieved.
When the photoresist film PF1 on which the first design pattern CP1 is drawn is then developed, a photoresist mask having a pattern corresponding to the first design pattern CP1 is formed. Here, when a particle P is accidentally attached to the photoresist film PF1 before the development, as shown in
Next, an inspection of the metal film 14 having the defect D shown in
Referring to
Next, the second design data is corrected based on the third design data.
Subsequently, as shown in
Next, the photoresist film PF2 is developed, thereby obtaining a photoresist mask PM2 as shown in
Next, as shown in
Subsequently, the quartz substrate 12 is etched using the hard mask HM (
As described above, in the original plate manufacturing method according to the present embodiment, the first design data and the second design data are first generated. The first design data and the second design data respectively correspond to the first design pattern CP1 and the second design pattern CP2, which together constitute the template pattern to be formed on the template. Next, the surface of the metal film 14 onto which the first design pattern CP1 is transferred is observed, and defects of the metal film 14 are thus detected. The third design data for repairing the detected defect is generated, and the second design pattern CP2 is adjusted based on the third design data. Based on the design data corresponding to the corrected second design pattern CCP2, the photoresist film PF2 coated onto the metal film 14 is irradiated with a charged particle beam, and the corrected second design pattern CCP2 is transferred onto the metal film 14. As a result, the hard mask HM is obtained. The hard mask HM has not only the second design pattern CP2 but also the third design pattern CP3 for repairing the detected defect in the first design pattern CP1. Therefore, the hard mask HM can have a pattern matching the intended template pattern, and the quartz substrate 12 can be etched using the hard mask HM, thereby obtaining the patterned template.
That is, according to the original plate manufacturing method of the present embodiment, the corrected second design pattern CCP2 is transferred onto the metal film 14 onto which the first design pattern CP1 has already transferred, and therefore, defects in the metal film 14 that occurred when the first design pattern CP1 was transferred can be repaired in the subsequent lithography process. Therefore, it is possible to manufacture a template having a desired template pattern with reduced defects.
Further, since the defect occurred in the metal film 14 during the transfer of the first design pattern CP1 can be repaired when the corrected second design pattern CP2 is transferred, rework immediately after the transfer of the first design pattern CP1 does not need to be performed. Thus, an extra process can be avoided, and the template can be manufactured in a short time.
If no defect is found during observation of the surface of the metal film 14 on which the first design pattern CP1 has been formed, the photoresist film PF2 is irradiated with a charged particle beam based on the second design data corresponding to the second design pattern CP2.
Next, a modification example of the original plate manufacturing method according to the first embodiment will be described. In this modification example, the second design pattern CP2 is adjusted (corrected) by a different method.
As shown in
The proximity effect is a phenomenon in which the one irradiated region is expanded in size/dimension due to scattering or reflecting of the irradiated charged particle beam within the photoresist film (PF2) from nearby (proximate) exposures. The effect is particularly remarkable when the adjacent irradiated region(s) irradiated by the charged particle beam are close to one another. When a pattern (portion P2), which is not present in the original second design pattern CP2, is added as in the corrected second design pattern CCP4, the spacing between the portion P2 and each portion P10 is narrower than the spacing between the portions P1, which is likely to produce the proximity effect. Therefore, by providing the narrowed width portion NW having a smaller pattern width in the portion P10, the distance from the portion P2 is increased, and an influence on the proximity effect is reduced or compensated. That is, the second design pattern CP2 is not only corrected based on the third design pattern CP3, but also corrected by providing the narrowed width portion NW. The metal film 14 (including the defect D) onto which the first design pattern CP1 was transferred is patterned using the corrected second design pattern CCP4 thus obtained, thereby obtaining a hard mask HM with the intended pattern. As shown in
The appropriate width and/or length (along the longitudinal direction of the portion P10) of the narrowed width portion NW may be determined by, for example, an irradiation dose correction method disclosed in JP-A-9-289164. This reference (JP-A-9-289164) discloses a method of calculating an optimal irradiation dose of the charged particle beam based on a size or density of the pattern (without considering defect or the like), spacing, and the like, in order to efficiently reduce the influence on the proximity effect in a charged beam drawing method. Since such a calculation is generally performed on the pattern corresponding to the entire chip, the amount of calculation involved will be large. However, in the original plate manufacturing method based on the modification example, the calculation can be performed only around the defect(s) D detected by the surface inspection, and therefore, the width or length of the narrowed width portion NW can be determined in a short time. Furthermore, improvement in calculation accuracy is expected since calculations are necessary only for small regions.
When the portion P10 is exposed in the photoresist film (PF2), a focusing diameter of the charged particle beam may be reduced and shifted when the charged particle beam has reached the narrowed width portion NW. Furthermore, when the portion P10 is formed by reciprocating the charged particle beam along the longitudinal direction of the portion P10 multiple times, the charged particle beam can be stopped in a predetermined period when the charged particle beam has reached the narrowed width portion NW, and then the irradiation can resume once the narrowed width portion NW region is passed. Furthermore, the irradiation dose of the charged particle beam can be reduced, such that the narrowed width portion NW may be realized. Accordingly, since the scattering or reflection of the charged particle beam in the photoresist film (PF2) is reduced, the influence on the proximity effect is reduced. That is, the portion irradiated with a low irradiation dose can be the narrowed width portion NW. Additionally, the irradiation dose of the charged particle beam may be reduced based on the narrowed width portion NW obtained by the calculation.
Although the original plate manufacturing method according to the first embodiment has been described so far, the present disclosure can also be implemented as a drawing data creation method and a pattern defect repairing method.
In the pattern defect repairing method according to the second embodiment, in step S1, the first design data and the second design data are generated. The first design data and the second design data each respectively correspond to the first design pattern and the second design pattern which are the formed patterns which together constitute the intended original plate pattern. The first design data includes information on a shape or line width of the first design pattern CP1, information on an intensity (irradiation dose) of the charged particle beam when using the charged particle beam, and the like, and the second design data also includes information on a shape or line width of the second design pattern CP2, information on an electron beam intensity (irradiation dose), and the like.
Next, in step S2, the first design pattern is formed, based on the first design data, on an object on which the intended pattern is to be formed. Instep S3, the formed first design pattern is observed, and image data is acquired. Next, in the second embodiment, the first design data and the image data are compared in step S4.
A difference between the first design data and the image data can then be detected (step S5). If there is no difference (step S5; NO), the second design pattern is formed, based on the second design data, on the object on which the first design pattern has already been formed (step S9), and the series of processes is completed.
On the other hand, if there is a difference between the first design data and the image data (step S5; YES), the third design data corresponding to the third design pattern is generated based on the difference (Step S6). Next, in step S7, the second design data is corrected (adjusted) based on the third design data. In step S8, the object on which the first design pattern has been formed is patterned based on the corrected second design data. The series of processes is now completed.
As a modification example of the second embodiment, the third design data maybe generated using a pattern recognition technique based on the image data acquired in step S3 instead of the comparison processing between first design data and the image data of step S4 to step S6.
In the embodiments described above, the design data corresponding to the template pattern includes two individual data sets of the first design data corresponding to the first design pattern CP1 and the second design data corresponding to the second design pattern CP2. However, the sets of design data is not limited two, and the template pattern may comprise three or more individual sets of design data. In this case, the second design pattern is formed on the metal film 14 while repairing the first design pattern based on the corrected second design data (
In an above-described embodiment, the third design data showing the third design pattern corresponding to a difference between the first design pattern and an observation image is generated, but the third design data may not necessarily be data showing a design pattern. For example, the third design data can be data which is associated with information indicating the presence/absence of a coordinate position and the defect in the coordinate position, obtained by comparing between the first design data corresponding to the first design pattern and the image data of the observation image. In other words, the third design data can correct the second design data.
In embodiments described above, the hard mask HM is obtained by patterning the metal film 14 based on the corrected second design data, and the quartz substrate 12 is then etched using the hard mask HM. However, the quartz substrate 12 may be etched after the first design pattern is formed on the metal film 14 (after
In embodiments described above, a case of manufacturing the template as an original plate has been described as an example. However, a case of manufacturing a photomask (reticle) as an original plate can be applied to the present embodiment. In this case, as shown in
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the disclosure. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein maybe made without departing from the spirit of the disclosure. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosure.
Number | Date | Country | Kind |
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2020-131828 | Aug 2020 | JP | national |