Patent Application
20220139778
The present invention relates to a manufacturing method of a contact structure, and more particularly, to a manufacturing method of a contact structure including an exposure process.
Integrated circuit (IC) is constructed by devices and interconnections, which are formed by patterned feature in the substrate or different layers. In the fabrication of IC, the photolithography process is an essential technique. The photolithography process is configured to form designed patterns such as circuit layout patterns on one or more photomasks, and then to precisely transfer such patterns to a photoresist layer on a film by exposure and development steps. Subsequently, the complicated layout patterns are precisely transferred to a semiconductor chip by an etching process using the patterned photoresist layer as a mask.
However, in the above-mentioned manufacturing process, many factors (such as process stability, uniformity, condition of the substrate, etc.) will influence the manufacturing result and may lead to the formation of defects, and the production yield of the product may be influenced accordingly. Therefore, how to reduce defects and improve production yield through the combination of the process condition design and/or inspection approaches has always been the direction of the efforts of the related fields.
It is one of the objectives of the present invention to provide a manufacturing method of a contact structure. Different exposure steps are performed to different regions of a substrate, respectively, and some of the exposure steps are performed with an overlay shift. The process margin in some regions may become smaller accordingly, and defects generated in subsequent processes may be detected more easily. Therefore, the manufacturing method may be used to modify related process conditions for improving the manufacturing yield.
According to an embodiment of the present invention, a manufacturing method of a contact structure is provided. The manufacturing method includes the following steps. Firstly, a substrate is provided, and the substrate includes a first region and a second region. A dielectric layer is formed on the substrate, and a photoresist layer is formed on the dielectric layer. An exposure process is performed. The exposure process includes a plurality of first exposure steps and a plurality of second exposure steps. Each of the first exposure steps is performed to a part of the first region of the substrate. Each of the second exposure steps is performed to a part of the second region of the substrate, and each of the second exposure steps is performed with a first overlay shift by a first predetermined distance. Subsequently, a develop process is performed for forming a plurality of openings in the photoresist layer.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
The present invention has been particularly shown and described with respect to certain embodiments and specific features thereof. The embodiments set forth herein below are to be taken as illustrative rather than limiting. It should be readily apparent to those of ordinary skill in the art that various changes and modifications in form and detail may be made without departing from the spirit and scope of the present invention.
Before the further description of the preferred embodiment, the specific terms used throughout the text will be described below.
The terms “on,” “above,” and “over” used herein should be interpreted in the broadest manner such that “on” not only means “directly on” something but also includes the meaning of “on” something with an intermediate feature or a layer therebetween, and that “above” or “over” not only means the meaning of “above” or “over” something but can also include the meaning it is “above” or “over” something with no intermediate feature or layer therebetween (i.e., directly on something).
The ordinal numbers, such as “first”, “second”, etc., used in the description and the claims are used to modify the elements in the claims and do not themselves imply and represent that the claim has any previous ordinal number, do not represent the sequence of some claimed element and another claimed element, and do not represent the sequence of the manufacturing methods, unless an addition description is accompanied. The use of these ordinal numbers is only used to make a claimed element with a certain name clear from another claimed element with the same name.
The term “etch” is used herein to describe the process of patterning a material layer so that at least a portion of the material layer after etching is retained. When “etching” a material layer, at least a portion of the material layer is retained after the end of the treatment. In contrast, when the material layer is “removed”, substantially all the material layer is removed in the process. However, in some embodiments, “removal” is considered to be a broad term and may include etching.
The term “forming” or the term “disposing” are used hereinafter to describe the behavior of applying a layer of material to the substrate. Such terms are intended to describe any possible layer forming techniques including, but not limited to, thermal growth, sputtering, evaporation, chemical vapor deposition, epitaxial growth, electroplating, and the like.
Please refer to
In some embodiments, the exposure process 91 may include a plurality of normal exposure steps performed without intentional overlay shifts and a plurality of deviated exposure steps performed with overlay shifts, and the overlay shifts of at least two of the deviated exposure steps may be different from each other. The normal exposure steps and the deviated exposure steps may be performed to different regions of the substrate 10 respectively. Therefore, the normal exposure steps and the deviated exposure steps may be different exposure shots in the exposure process 91 respectively, and exposed regions corresponding to the normal exposure steps and exposure regions corresponding to the normal exposure steps and the deviated exposure steps may not overlap one another or partially overlap at a peripheral portion of each exposed region, but not limited thereto. In some embodiments, the exposure process 91 may be performed in an exposure apparatus. The exposure apparatus may include a stepper exposure machine, a scanner exposure machine, or other exposure apparatus that can be used in semiconductor manufacturing processes. The wavelength range of the exposure light source used in the exposure apparatus and the dose of each exposure shot may be adjusted and selected according to the material characteristics of the photoresist layer, the resolution requirements of the product, and/or other process considerations.
In some embodiments, the exposure process 91 may include a plurality of first exposure steps 91A and a plurality of second exposure steps 91B. Each of the first exposure steps 91A is performed to a part of the first region R1 of the substrate 10. Each of the second exposure steps 91B is performed to a part of the second region R2 of the substrate 10, and each of the second exposure steps 91B is performed with a first overlay shift by a first predetermined distance. In other words, each of the first exposure steps 91A may be regarded as the above-mentioned normal exposure step performed without an intentional overlay shift, and each of the second exposure steps 91B may be regarded as the above-mentioned deviated exposure step performed with an overlay shift. In some embodiments, each of the first exposure steps 91A may be performed with a photomask (not shown in
In some embodiments, the first exposure steps 91A may be performed to different parts in the first region R1 of the substrate 10, and the second exposure steps 91B may be performed to different parts in the second region R2 of the substrate 10. For example, as shown in
Please refer to
In some embodiments, each of the second exposure steps 91B may be regarded as the above-mentioned deviated exposure step performed with the overlay shift, and the second exposure step 91B may include but is not limited to the step S21, the step S22, and the step S23 described above. Therefore, the second exposure step 91B may include adjusting a position of the photomask and/or a position of the substrate 10 for generating the first overlay shift and illuminating the substrate 10 by exposure light passing through a part of the photomask with the first overlay shift. Additionally, each of the first exposure steps 91A may be regarded as the above-mentioned normal exposure step performed without an intentional overlay shift. Therefore, in some embodiments, the first exposure step 91A may be similar to the second exposure step 91B except for the above-mentioned step for generating the overlay shift (such as the step S22 described above), and the first exposure step 91A may include performing an alignment step for aligning the substrate 10 and the photomask and illuminating a part of the substrate 10 by exposure light passing through the photomask without an intentional overlay shift between the substrate 10 and the photomask. It is worth noting that there may be an inevitable overlay shift in the exposure result of the normal exposure step performed without an intentional overlay shift because of the influence of process stability, but the overlay shift of the deviated exposure step performed with the intentional overlay shift is different from the inevitable overlay shift possibly occurring in the normal exposure step, and at least some of the overlay shifts of the deviated exposure steps may be greater than the inevitable overlay shift possibly occurring in the normal exposure step.
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Additionally, in some embodiments, the regions (such as the first region R1, the second region R2, the third region R3, and the fourth region R4) corresponding to the normal exposure steps performed without intentional overlay shifts (such as the first exposure steps 91A) and the deviated exposure steps performed with different overlay shifts (such as the second exposure steps 91B, the third exposure steps 91C, and the third exposure steps 91D) in the substrate 10 may be arranged in a matrix configuration for distinguish the corresponding exposure condition more conveniently in the defect inspection performed subsequently, and the exposure process 91 may be regarded as an exposure process with an overlay shift matrix, but not limited thereto. Additionally, the regions corresponding to the normal exposure steps performed without intentional overlay shifts (such as the first exposure steps 91A) in the substrate 10 may be disposed adjacent to one another and disposed in a centralized configuration, and the regions corresponding to the deviated exposure steps performed different overlay shifts (such as the second exposure steps 91B, the third exposure steps 91C, and the fourth exposure steps 91D) in the substrate 10 may be disposed adjacent to one another and disposed in a centralized configuration respectively. In other words, there is not a region corresponding to the deviated exposure step and disposed between two regions corresponding to two first exposure steps 91A respectively in the first region R1; there is not a region corresponding to the first exposure step 91A and disposed between two regions corresponding to two second exposure steps 91B in the second region R2; there is not a region corresponding to other deviated exposure step (such as the third exposure step 91C and/or the fourth exposure step 91D) and disposed between two regions corresponding to two second exposure steps 91B in the second region R2; there is not a region corresponding to the first exposure step 91A and disposed between two regions corresponding to two third exposure steps 91C in the third region R3; there is not a region corresponding to other deviated exposure step (such as the second exposure step 91B and/or the fourth exposure step 91D) and disposed between two regions corresponding to two third exposure steps 91C in the third region R3; there is not a region corresponding to the first exposure step 91A and disposed between two regions corresponding to two fourth exposure steps 91D in the fourth region R4; and there is not a region corresponding to other deviated exposure step (such as the second exposure step 91B and/or the third exposure step 91C) and disposed between two regions corresponding to two fourth exposure steps 91D in the fourth region R4.
As shown in
In addition, the photomask used in each of the first exposure steps 91A may be regarded as a first photomask M1, the photomask used in each of the second exposure steps 91B may be regarded as a second photomask M2, the photomask used in each of the third exposure steps 91C may be regarded as a third photomask M3, and the photomask used in each of the fourth exposure steps 91D may be regarded as a fourth photomask M4. In some embodiments, the first exposure steps 91A, the second exposure steps 91B, the third exposure steps 91C, and the fourth exposure steps 91D may be performed with the same photomask, and the first photomask M1, the second photomask M2, the third photomask M3, and the fourth photomask M4 may be the identical photomask, but not limited thereto. In some embodiments, the first exposure step 91A, the second exposure step 91B, the third exposure step 91C, and the fourth exposure step 91D may be performed with different photomasks, respectively, according to design and/or product requirements.
In some embodiments, before the step of forming the dielectric layer described above, a plurality of active regions AA and a plurality of gate structures GS may be formed on the substrate 10. For example, before the step of forming the dielectric layer described above, at least one first active region AA1, at least one second active region AA2, at least one third active region AA3, and at least one fourth active region AA4 may be formed in the first region R1, the second region R2, the third region R3, and the fourth region R4 of the substrate 10, respectively, and at least one first gate structure GS1, at least one second gate structure GS2, at least one third gate structure GS3, and at least one fourth gate structure GS4 may be formed on the first region R1, the second region R2, the third region R3, and the fourth region R4 of the substrate 10, respectively, but not limited thereto. Additionally, the dielectric layer may cover the first active region AA1, the second active region AA2, the third active region AA3, the fourth active region AA4, the first gate structure GS1, the second gate structure GS2, the third gate structure GS3, and the gate structure GS4, but not limited thereto. Additionally, the photomask used in the exposure process 91 may include a plurality of contact patterns for corresponding to the locations of contact structures formed on the substrate 10. For instance, the first photomask M1, the second photomask M2, the third photomask M3, and the fourth photomask M4 may include a first contact pattern CT1, a second contact pattern CT2, a third contact pattern CT3, and a fourth contact pattern CT4, respectively. When the first photomask M1, the second photomask M2, the third photomask M3, and the fourth photomask M4 are one identical photomask, the first contact pattern CT1, the second contact pattern CT2, the third contact pattern CT3, and the fourth contact pattern CT4 may be the same contact pattern in the photomask or different contact patterns in the photomask, but not limited thereto.
In some embodiments, a first exposed region EA1 that is formed in the photoresist layer and formed by at least one of the first exposure steps 91A via the first contact pattern CT1 may overlap a part of the first active region AA1 in a vertical direction (such as a third direction D3) and overlap a part of the first gate structure GS1 in the third direction D3; a second exposed region EA2 that is formed in the photoresist layer and formed by at least one of the second exposure steps 91B via the second contact pattern CT2 may overlap a part of the second active region AA2 in the third direction D3 and overlap a part of the second gate structure GS2 in the third direction D3; a third exposed region EA3 that is formed in the photoresist layer and formed by at least one of the thirds exposure steps 91C via the third contact pattern CT3 may overlap a part of the third active region AA3 in the third direction D3 and overlap a part of the third gate structure GS3 in the third direction D3; and a fourth exposed region EA4 that is formed in the photoresist layer and formed by at least one of the fourth exposure steps 91D via the fourth contact pattern CT4 may overlap a part of the fourth active region AA4 in the third direction D3 and overlap a part of the fourth gate structure GS4 in the third direction D3, but not limited thereto. In some embodiments, the third direction D3 described above may be regarded as a thickness direction of the substrate 10 and may be substantially orthogonal to a surface of the substrate 10, but not limited thereto. In addition, it is worth noting that the first contact pattern CT1 and the first exposed region EA1 represented in
In some embodiments, each of the gate structures GS and the corresponding active region AA may be disposed adjacent to each other in a horizontal direction (such as a first direction D1). For instance, the first gate structure GS1 and the first active region AA1 may be disposed adjacent to each other in the first direction D1, the second gate structure GS2 and the second active region AA2 may be disposed adjacent to each other in the first direction D1, the third gate structure GS3 and the third active region AA3 may be disposed adjacent to each other in the first direction D1, and the fourth gate structure GS4 and the fourth active region AA4 may be disposed adjacent to each other in the first direction D1. Additionally, in some embodiments, in the top-view diagram, the active region AA may be substantially elongated in the first direction D1, the gate structure GS may be substantially elongated in a second direction D2, and the second direction D2 may be substantially orthogonal to the first direction D1, but not limited thereto.
In some embodiments, the overlay shifts if different deviated exposure steps may be generated in the same direction for changing an area where the contact pattern and the active region overlap and an area where the contact pattern and the gate structure overlap. For instance, the first overlay shift OS1 of each of the second exposure steps 91B, the second overlay shift OS2 of each of the third exposure steps 91C, and the third overlay shift of each of the fourth exposure steps 91D may be generated in the first direction D1. Therefore, an area of the part of the second active region AA2 overlapped by the second exposed region EA2 in the third direction D3 may be smaller than an area of the part of the first active region AA1 overlapped by the first exposed region EA1 in the third direction D3; an area of the part of the third active region AA3 overlapped by the third exposed region EA3 in the third direction D3 may be smaller than the area of the part of the first active region AA1 overlapped by the first exposed region EA1 in the third direction D3 and greater than the area of the part of the second active region AA2 overlapped by the second exposed region EA2 in the third direction D3; and an area of the part of the fourth active region AA3 overlapped by the fourth exposed region EA4 in the third direction D3 may be smaller than the area of the part of the first active region AA1 overlapped by the first exposed region EA1 in the third direction D3 and greater than the area of the part of the third active region AA3 overlapped by the third exposed region EA3 in the third direction D3. Comparatively, an area of the part of the second gate structure GS2 overlapped by the second exposed region EA2 in the third direction D3 may be greater than an area of the part of the first gate structure GS1 overlapped by the first exposed region EA1 in the third direction D3, an area of the part of the third gate structure GS3 overlapped by the third exposed region EA3 in the third direction D3 may be greater than the area of the part of the first gate structure GS1 overlapped by the first exposed region EA1 in the third direction D3 and smaller than the area of the part of the second gate structure GS2 overlapped by the second exposed region EA2; and an area of the part of the fourth gate structure GS4 overlapped by the fourth exposed region EA4 in the third direction D3 may be greater than the area of the part of the first gate structure GS1 overlapped by the first exposed region EA1 in the third direction D3 and smaller than the area of the part of the third gate structure GS3 overlapped by the third exposed region EA3 in the third direction D3, but not limited thereto.
Please refer to
In some embodiments, before the step of forming the photoresist layer 23, a dielectric layer 21 and an anti-reflection layer 22 may be formed on the dielectric layer 18. The dielectric layer 21 may include an organic distribution layer (ODL) or other suitable organic or inorganic materials. The anti-reflection layer 22 may include a silicon-containing hard mask bottom anti-reflecting coating (SHB) layer or other suitable anti-reflection materials. The dielectric layer 18 may include a single layer or multiple layers of dielectric materials, such as silicon oxide, silicon nitride, silicon oxynitride, or other suitable dielectric materials. In each exposure step of the exposure process 91, the photoresist layer 23 on the substrate 10 may be illuminated by exposure light EL passing through a part of the photomask M. In some embodiments, the contact pattern CT in the photomask M may be a light transmission area, and the exposure light EL may pass through the contact pattern CT of the photomask M for illustrating the photoresist layer 23 on the substrate 10, in order to transfer the contact pattern CT to the photoresist layer 23 by a required proportion and form the exposed region EA in the photoresist layer 23, but not limited thereto. Therefore, in the deviated exposure step described above, the exposure light EL may pass through the photomask M for illustrating the photoresist layer 23 with the intentional overlay shift between the photomask M and the substrate 10, in order to change the location of the exposed region in the photoresist layer 23 and the located of the contact structure subsequently formed.
Please refer to
In some embodiments, overlap areas OA where the openings OP overlap the active regions AA in the third direction D3 within different regions may be different from one another because the first exposure step may be the normal exposure step performed without an intentional overlay shift, and the second exposure step, the third exposure step, and the fourth exposure step may be deviated exposure steps with different overlay shifts respectively. For instance, a first overlap area OA1 where the first opening OP1 on the first region R1 and the first active region AA1 overlap each other in the third direction D3 may be relatively larger; a second overlap area OA2 where the second opening OP2 on the second region R2 and the second active region AA2 overlap each other in the third direction D3 may be smaller than the first overlap area OA1; a third overlap area OA3 where the third opening OP3 on the third region R3 and the third active region AA3 overlap each other in the third direction D3 may be smaller than the first overlap area OA1 and greater than the second overlap area OA2; and a fourth overlap area OA4 where the fourth opening OP4 on the fourth region R4 and the fourth active region AA4 overlap each other in the third direction D3 may be smaller than the first overlap area OA1 and greater than the third overlap area OA3, but not limited thereto.
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Therefore, the condition of each contact structure CS on the substrate 10 may be scanned by the electron beam inspection for calculating the proportion of contact structure defects occurring in the regions corresponding to the normal exposure steps and the deviated exposure steps on the substrate 10, and that may be used as a reference and/or basis for adjusting the etching process described above. For example, when the number of contact structure defects is obviously positively correlated with the overlay shift amount of the deviated exposure step, if the number of contact structure defects is reduced effectively by modifying the process conditions of the etching process for forming the contact hole CH, the modified etching process may have an improved process window. Therefore, the manufacturing method of the contact structure in the present invention may be used to improve the process window of the contact structure and enhance the manufacturing yield of the related products.
To summarize the above descriptions, in the manufacturing method of the contact structure according to the present invention, different exposure steps may be performed to different regions of the substrate, respectively, and some of the exposure steps are performed with overlay shifts. The process margin in some regions may become smaller accordingly, and the defects generated in subsequent processes may be detected more easily. Therefore, the manufacturing method may be used to modify related process conditions for improving the manufacturing yield of the contact structure.
Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202011208320.8 | Nov 2020 | CN | national |
