Method for preparing identification mark used in self-aligned inversion patterning process

Abstract

The present invention provides a method for preparing an identification mark used in a self-aligned inverted patterning process, in which, during the process of performing the self-aligned inverted patterning process, the strip pattern is automatically shed by shrinking, or the third film layer is completely consumed, so as to reduce the pattern density of the identification mark finally formed. Therefore, the identification mark formed by the preparation method provided by the present invention is compatible with the self-aligned inverted patterning process, and the identification mark finally formed has a lower pattern density, which is conducive to improving the recognition accuracy of the device for the identification mark.

Description

Technical Field

[0001] The invention relates to the field of semiconductor technology, and in particular to a method for preparing an identification mark used in a self-aligned inversion pattern process. Background Art

[0002] In semiconductor manufacturing, in addition to forming relevant film layers for forming functional devices in the device area, identification marks are usually formed outside the device area. The identification marks can be used to achieve position alignment between multiple photolithography processes to avoid large position offsets between upper and lower film layers. Therefore, in order to more accurately characterize the film layer conditions formed in the device area, it is usually hoped that the preparation process of the identification mark is consistent with the preparation process used for the film layer in the device area, so that the graphic features of the identification mark are the same or similar to the graphic features in the device area.

[0003] With the development of semiconductor technology, the patterning process used has become more sophisticated, and the corresponding identification marks formed at this time also present a higher density pattern arrangement. For example, when using the Self-Aligned Reverse Patterning (SARP) process to increase the line density, the identification marks formed based on this patterning process also have a high-density pattern arrangement. However, the high-density identification marks are not conducive to identification by the identification equipment, and the deviation caused by poor identification will affect the alignment accuracy between the upper and lower film layers. Summary of the invention

[0004] The object of the present invention is to provide a method for preparing an identification mark used in a self-aligned inversion pattern process, so as to solve the problem that the identification mark formed by the existing process is difficult to be recognized by the equipment.

[0005] In order to solve the above technical problems, the present invention provides a method for preparing an identification mark used in a self-aligned inverted graphic process, comprising: forming a first film layer on a substrate, wherein a plurality of strip patterns are formed in the first film layer, and the width of the strip pattern is less than a predetermined width; forming a second film layer, wherein the second film layer covers the top surface and side walls of the strip pattern, and also covers the substrate surface between adjacent strip patterns; forming a third film layer, wherein the third film layer fills the gap between adjacent strip patterns and is located on the second film layer; and performing an etching process to remove the portion of the second film layer covering the top surface of the strip pattern and the portion located between the third film layer and the strip pattern, and causes the strip pattern to fall off the substrate.

[0006] Optionally, the predetermined width is no greater than 40 nm.

[0007] Optionally, the predetermined width is half of the width of the third film layer.

[0008] Optionally, a top surface of the third film layer is higher than a top surface of the stripe pattern.

[0009] Optionally, before forming the stripe pattern, an insulating layer is further formed on the substrate, and after etching the second film layer, at least the insulating layer between the third film layer and the stripe pattern is exposed, and the exposed insulating layer is further etched.

[0010] Optionally, the material of the second film layer is different from the materials of the first film layer and the third film layer.

[0011] The present invention also provides another method for preparing an identification mark used in a self-aligned inverted pattern process, comprising: providing a substrate, defining a device area on the substrate, and defining a marking area in a blank area outside the device area; forming a first film layer in the device area and the marking area, wherein a plurality of strip patterns are formed in the first film layer; forming a second film layer, wherein the second film layer covers the top surface and side walls of the strip patterns, and also covers the substrate surface between adjacent strip patterns; forming a third film layer by a spin coating process, wherein the coating of the third film layer fills the device area and the marking area, and spreads to the blank area outside the marking area, so that the height of the coating filled in the marking area is lower than the height of the coating filled in the device area; and performing an etching process to remove the portion of the second film layer covering the top surface of the strip pattern and the portion between the third film layer and the strip pattern, and also remove the third film layer in the marking area.

[0012] Optionally, the forming of the third film layer using the spin coating process includes: coating the third film layer with coating using the spin coating process, wherein the coating height of the third film layer in the marking area is lower than the coating height of the third film layer in the device area, and the coating height of the third film layer in the device area is higher than the gap height between adjacent strip patterns; and, performing a back etching process to reduce the coating height of the third film layer until the coating height of the third film layer in the device area is no higher than the gap height between adjacent strip patterns, and the coating height in the marking area is lower than half of the gap height.

[0013] Optionally, the width of the stripe pattern in the marking area is greater than the gap between adjacent stripe patterns.

[0014] Optionally, the width of the stripe pattern in the device region is less than or equal to the gap between adjacent stripe patterns.

[0015] In the preparation method of the identification mark used in the self-aligned inverted pattern process provided by the present invention, it is compatible with the self-aligned inverted pattern process, and the identification mark finally formed has a lower pattern density. Specifically, in the process of performing the self-aligned inverted pattern process, by reducing the width of the stripe pattern in the first film layer, the stripe pattern can be automatically detached and removed in the subsequent steps; or, by utilizing the difference between the mark area and the device area, the height of the third film layer in the mark area is lower than the height of the third film layer in the device area, so that the third film layer with a lower height in the mark area can be consumed in the subsequent etching process, so that the identification mark finally formed has a lower pattern density, which is conducive to improving the recognition accuracy of the recognition device for the formed identification mark.

[0016] Therefore, the identification mark formed based on the self-aligned inverted graphic process provided by the present invention can not only accurately reflect the process status of the current self-aligned inverted graphic process, but also the graphic density of the prepared identification mark will not be too large, thereby improving the recognition ability of the identification device to the identification mark, and thus helping to improve the recognition accuracy of the identification mark. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A method for preparing an identification mark applicable to a self-aligned inverted patterning process provided by the present invention is shown.

[0018] Figure 2-Figure 6 It is a schematic diagram of the structures in the device area and the mark area during the self-aligned inversion patterning process in the first embodiment of the present invention.

[0019] Figure 7 The present invention provides another method for preparing an identification mark applicable to a self-aligned inverted pattern process.

[0020] Figure 8 It is a schematic diagram of setting the marking area in an open area in the second embodiment of the present invention.

[0021] Figure 9a-Figure 11a It is a schematic diagram of the structure in the device area during the self-aligned inversion patterning process in the second embodiment of the present invention.

[0022] Figure 9b-Figure 11b It is a schematic diagram of the structure in the marking area during the self-aligned inversion patterning process in the second embodiment of the present invention.

[0023] The reference numerals are as follows:

[0024] 100-substrate;

[0025] 110-insulating layer;

[0026] 200-first film layer;

[0027] 210 / 210' - bar pattern;

[0028] 300-mask layer;

[0029] 400- second film layer;

[0030] 500 / 500'-third membrane layer. DETAILED DESCRIPTION

[0031] The core idea of ​​the present invention is to provide a method for preparing an identification mark that can be applied to a self-aligned inverted patterning process. Specifically, the identification mark in the present invention is prepared by using a self-aligned inverted patterning process, which can accurately reflect the process status of the current self-aligned inverted patterning process, and the pattern density of the prepared identification mark is not too large, which improves the recognition ability of the identification device to the identification mark, thereby facilitating the improvement of the recognition accuracy of the identification mark.

[0032] For example, you can refer to Figure 1 , Figure 1 A method for preparing an identification mark applicable to a self-aligned inverted patterning process provided by the present invention is shown, and includes the following steps.

[0033] Step S11, forming a first film layer on a substrate, wherein a plurality of stripe patterns are formed in the first film layer, and the width of the stripe pattern is smaller than a preset width.

[0034] Step S12, forming a second film layer, wherein the second film layer covers the top surface and the sidewalls of the stripe patterns, and also covers the substrate surface between adjacent stripe patterns.

[0035] Step S13, forming a third film layer, wherein the third film layer fills the gaps between adjacent strip patterns and is located on the second film layer.

[0036] Step S14, performing an etching process to remove the portion of the second film layer covering the top surface of the stripe pattern and the portion between the third film layer and the stripe pattern, and causing the stripe pattern to fall off the substrate.

[0037] The present invention also provides another method for preparing an identification mark that can be applied to a self-aligned inversion patterning process. Figure 7 , which includes the following steps.

[0038] In step S21, a substrate is provided. A device area is defined on the substrate, and a mark area is defined in a blank area outside the device area.

[0039] Step S22 , forming a first film layer in the device area and the marking area, wherein the first film layer includes a plurality of stripe patterns.

[0040] Step S23 , forming a second film layer, wherein the second film layer covers the top surface and the sidewalls of the stripe patterns, and also covers the substrate surface between adjacent stripe patterns.

[0041] Step S24, forming a third film layer by spin coating, wherein the coating of the third film layer fills the device area and the mark area and spreads to the blank area outside the mark area, so that the height of the coating filled in the mark area is lower than the height of the coating filled in the device area.

[0042] Step S25 , performing an etching process to remove the portion of the second film layer covering the top surface of the stripe pattern and the portion between the third film layer and the stripe pattern, and also removing the third film layer in the marking area.

[0043] That is, the method for preparing the identification mark applicable to the self-aligned inverted graphic process provided by the present invention is still prepared by the self-aligned inverted graphic process, and in the graphic process, the stripe pattern in the first film layer or the third film layer is automatically removed, so that the retained film layer has a smaller graphic density (specifically, when the stripe pattern is automatically removed, there is a larger gap between adjacent third film layers; and, when the third film layer is automatically removed, there is a larger gap between adjacent stripe patterns), thereby improving the recognition accuracy of the recognition device for the formed recognition mark.

[0044] The following is a further detailed description of the method for preparing the identification mark applicable to the self-aligned inverted patterning process proposed by the present invention in conjunction with the accompanying drawings and specific embodiments. According to the following description, the advantages and features of the present invention will become clearer. It should be noted that the accompanying drawings are all in a very simplified form and are not in precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. It should be recognized that relative terms such as "above", "below", "top", "bottom", "above" and "below" shown in the accompanying drawings can be used to describe the relationship between various elements. These relative terms are intended to cover different orientations of elements other than the orientations depicted in the accompanying drawings. For example, if the device is inverted relative to the view in the accompanying drawings, an element described as being "above" another element will now be below the element.

[0045] Embodiment 1

[0046] Combine the following Figure 1 as well as Figure 2-Figure 6 This embodiment is described, wherein Figure 2-Figure 6It is a schematic diagram of the structure of the identification mark in the first embodiment of the present invention during its preparation process. It should be noted that in order to more clearly compare the difference between the identification mark prepared by the self-aligned inversion pattern process in this embodiment and the conventional pattern in the device area, the structure diagram of the mark area Mark and the device area Cell are schematically shown in the accompanying drawings of this embodiment.

[0047] In step S11, refer to Figure 2 and Figure 3 As shown, a first film layer 200 is formed on a substrate 100 , wherein a plurality of stripe patterns are formed in the first film layer 200 , and a width D1 of the stripe pattern is smaller than a predetermined width.

[0048] In this embodiment, the width D1 of the stripe pattern 210 in the marking area Mark is reduced to less than a predetermined width, so that the stripe pattern 210 in the marking area Mark can be automatically detached from the substrate 100 in a subsequent etching process. The predetermined width is, for example, not greater than 40 nm (for example, in a specific example, the predetermined width can be selected from any value between 30 nm and 40 nm), and at this time, the width D1 of the stripe pattern 210 in the marking area Mark can be less than 40 nm.

[0049] Furthermore, the thickness of the first film layer 200 may be greater than or equal to 120 nm, so that the height of the stripe pattern 210 can be increased accordingly, so that the stripe pattern 210 can be more easily removed from the substrate 100 in subsequent processes.

[0050] Continue to refer Figure 3 As shown, the present embodiment also illustrates the structure in the device area Cell during the process of performing the self-aligned inversion patterning process. Specifically, when forming the first film layer 200, the first film layer 200 is simultaneously formed in the device area Cell and the marking area Mark, that is, a plurality of strip patterns are formed in both the device area Cell and the marking area Mark. Among them, the width D2 of the strip pattern 210' in the device area Cell will be greater than the width D1 of the strip pattern 210 in the marking area Mark, so that the strip pattern 210' in the device area Cell can still be retained in the subsequent etching process, and the strip pattern 210 in the marking area Mark can automatically fall off from the substrate 100 in the subsequent etching process. Therefore, it can also be considered that the width D2 of the strip pattern 210' in the device area Cell is greater than the predetermined width, and the spacing size between adjacent strip patterns 210 in the marking area Mark will be greater than the spacing size between adjacent strip patterns 210' in the device area Cell.

[0051] In a specific solution, the method for preparing a plurality of stripe patterns in the first film layer 200 includes: firstly referring to Figure 2As shown, a first film layer 200 is formed on the substrate 100, and a mask layer 300 is formed on the first film layer 200, wherein the mask layer 300 is used to define a pattern of a stripe pattern; Figure 3 As shown, the first film layer 200 is etched with the mask layer 300 as a mask to form a plurality of stripe patterns. The first film layer 200 may be an organic dielectric layer (ODL); and the material of the mask layer 300 may include, for example, silicon nitride or silicon oxide. In this embodiment, the first film layer 200 will be formed in the device area Cell and the mark area Mark at the same time, and the first film layer 200 in the device area Cell and the mark area Mark will be etched at the same time to form a stripe pattern 210' with a larger width in the device area Cell and a stripe pattern 210 with a smaller width in the mark area Mark.

[0052] In step S12, refer to Figure 4 As shown, a second film layer 400 is formed, and the second film layer 400 covers the top surface and the sidewall of the stripe pattern, and also covers the substrate surface between adjacent stripe patterns.

[0053] Specifically, the second film layer 400 can be formed by a deposition process, such as an atomic layer deposition process (ALD), so that the formed second film layer 400 has a thinner thickness and a more uniform thickness. In this embodiment, the thickness of the second film layer 400 can be set to, for example, 150 angstroms to 250 angstroms. Further, the material of the second film layer 400 can include silicon oxide.

[0054] Continue to refer Figure 4 As shown, in this embodiment, after the pattern of the stripe pattern is defined by the mask layer 300, the mask layer 300 is still retained, and the second film layer 400 covers the mask layer 300. In this embodiment, the material of the second film layer 400 can be the same as that of the mask layer 300, so that when the second film layer 400 is subsequently etched, the mask layer 400 can be removed at the same time.

[0055] In step S13, refer to Figure 5 As shown, a third film layer 500 is formed, and the third film layer 500 is filled in the gap between adjacent strip patterns and is located on the second film layer 400. In this embodiment, the third film layer 500 is filled in the gap between adjacent strip patterns, and at this time, the third film layer 500 filled between adjacent strip patterns can present a strip structure.

[0056] like Figure 5As shown, the spacing between adjacent strip patterns 210 in the mark area Mark is greater than the spacing between adjacent strip patterns 210' in the device area Cell, so the width D3 of the third film layer 500 in the mark area Mark will also be greater than the width D4 of the third film layer 500 in the device area Cell.

[0057] It should be noted that the purpose of using the self-aligned inversion patterning process is to improve the pattern density in the device area Cell, by removing the portion of the second film layer 400 between the first film layer 200 and the third film layer to separate the first film layer and the third film layer, and retaining the first film layer 200 and the third film layer 500' in the device area Cell, so as to form the high-density pattern required after patterning. Therefore, by reducing the thickness of the second film layer 400, it is beneficial to improve the pattern density after patterning; and, in the device area Cell, the width D2 of the strip pattern 210' and the width D4 of the third film layer 500' can be set to be the same or similar.

[0058] Different from the device area Cell, the width D3 of the third film layer 500 in the mark area Mark will be greater than the width D4 of the third film layer 500' in the device area Cell. That is, the width D1 of the stripe pattern 210 in the mark area Mark is less than the predetermined width (so that the stripe pattern 210 with a small width can be removed in the subsequent etching), the width D2 of the stripe pattern 210' in the device area Cell and the width D4 of the third film layer 500' are both greater than the predetermined width, and the width D3 of the third film layer 500 in the mark area Mark is further greater than the width D2 of the stripe pattern in the device area Cell and the width D4 of the third film layer 500'.

[0059] In this embodiment, for the marking area Mark, the width of the strip pattern 210 can also be designed according to the width of the third film layer 500. For example, half of the width D3 of the third film layer 500 can be set as the predetermined width. At this time, the width D1 of the strip pattern 210 can be designed to be smaller than half of the width D3 of the third film layer 500, that is, D1<0.5*D3.

[0060] Furthermore, the preparation method of the third film layer, for example, includes: first, forming a filling material layer on the substrate 100, the filling material layer filling the gap between adjacent strip patterns, and the height of the filling material layer is higher than the height of the gap; then, removing the portion of the filling material layer higher than the gap, so that the remaining film layer material is aligned and filled in the gap to form the third film layer. In this embodiment, the filling material layer is, for example, an organic dielectric layer, which can be formed by a spin coating process, and after the organic dielectric layer is spin-coated, the portion of the organic dielectric layer higher than the gap can be removed by an etch-back process, and the etching gas in the etch-back process used, for example, includes an oxygen-containing gas.

[0061] Continue to refer Figure 5 As shown, in the mark area Mark, the top surface of the third film layer 500 is flush with the top surface of the second film layer 400 covering the stripe pattern, so that the top surface of the third film layer 500 is higher than the top surface of the stripe pattern 210. In this embodiment, the top surface of the third film layer 500 is also higher than the top surface of the mask layer 300.

[0062] In step S14, refer to Figure 6 As shown, an etching process is performed to remove the portion of the second film layer 400 covering the top surface of the stripe pattern and the portion between the third film layer and the stripe pattern, and the stripe pattern 210 in the mark area Mark falls off from the substrate 100 .

[0063] In this embodiment, the material of the second film layer 400 includes silicon oxide, based on which, fluorine-containing gas can be used to etch the second film layer 400. In an optional solution, the material of the mask layer 300 can be the same as the material of the second film layer 400, so when etching the second film layer 400, the exposed mask layer 300 can also be removed.

[0064] Furthermore, the third film layer will also be partially consumed in the etching process. In the present embodiment, the etching process partially consumes the third film layer to reduce the height of the third film layer. In this way, the top surface of the third film layer 500' in the device area Cell can be close to the top surface of the strip pattern 210' (for example, the top surface of the strip pattern 210' is equal to or nearly equal to the top surface of the strip pattern 210'). In a specific example, a dry etching process can be used to etch the second film layer, during which the etching gas will simultaneously bombard the third film layer, causing the top of the third film layer to be partially consumed. Or in other examples, the etching process used has a higher etching rate for the second film layer and a lower etching rate for the third film layer, but the etching selectivity of the two is not much different, so that the third film layer is also consumed when etching the second film layer.

[0065] It should be noted that the strip pattern 210 in the marking area Mark has a relatively small width, and after undergoing the multiple processes described above, its adhesion to the substrate 100 is relatively poor, so that it is very easy to separate from the substrate 100 during the etching process. At this time, the third film layer 500 retained in the marking area 210 not only has a relatively large width, but also has a relatively large gap between adjacent third film layers 500, so that the graphic density of the formed marking pattern is relatively low and is easy to be recognized by the equipment. However, the strip pattern 210' in the device area Cell is still retained to achieve a high-density graphic process. It can be seen that in this embodiment, when the pattern of the identification mark is defined by the self-aligned inverted graphic process, it can reduce the graphic density in the marking area Mark while ensuring the high-density graphic requirements in the device area Cell.

[0066] In addition, among the optional options, focus on Figure 6 As shown, before forming the stripe pattern, an insulating layer 110 may be formed on the substrate 100, so that the stripe pattern, the second film layer and the third film layer are all formed on the insulating layer 110; and after performing an etching process to etch the second film layer, the insulating layer 110 may be exposed (wherein at least the insulating layer 110 located between the stripe pattern and the third film layer is exposed), and at this time, the exposed insulating layer 110 may be further etched. It should be noted that in the mark area Mark, by etching the exposed insulating layer 110, the suspended height of the stripe pattern can be further increased, so that the stripe pattern is easier to fall off.

[0067] Embodiment 2

[0068] The difference from the first embodiment is that in this embodiment, the identification mark is set in the open area, so that the height of the third film layer in the marking area is reduced, and can be consumed in the subsequent etching process. In this way, the retained strip pattern can be used to define the identification mark with lower graphic density.

[0069] Combine the following Figure 7 , Figure 8 , Figure 9a-Figure 11a , Figure 9b-Figure 11b This embodiment is described, wherein: Figure 8 It is a schematic diagram of setting the marking area in an open area in the second embodiment of the present invention;

[0070] Figure 9a-Figure 11a is a schematic diagram of the structure in the device area during the self-aligned inversion patterning process in the second embodiment of the present invention, Figure 9b-Figure 11b It is a schematic diagram of the structure in the marking area during the self-aligned inversion patterning process in the second embodiment of the present invention.

[0071] In step S21, a substrate 100 is provided, on which a device area Cell is defined, and a mark area Mark is defined in a blank area outside the device area Cell. Figure 8 As shown, the mark area Mark is set in the blank area, so the periphery of the mark area Mark is empty. In a specific example, the mark area Mark can be set in a blank area of ​​the scribe groove, for example.

[0072] In step S22, refer to Figure 9a and Figure 9b As shown, a first film layer 200 is formed in the device area Cell and the mark area Mark, and a plurality of stripe patterns are formed in the first film layer 200. Figure 9a The film structure in the cell of the device area is shown in the figure. Figure 9b The film structure in the mark area Mark is shown schematically.

[0073] In a specific solution, the method for preparing a plurality of stripe patterns in the first film layer 200 includes: forming the first film layer 200 on the substrate 100, and forming a mask layer 300 on the first film layer 200, wherein the mask layer 300 is used to define the pattern of the stripe pattern; and then referring to Figure 3 As shown, the first film layer 200 is etched using the mask layer 300 as a mask to form a plurality of stripe patterns. The first film layer 200 may be an organic dielectric layer (ODL); and the material of the mask layer 300 may include silicon nitride or silicon oxide, for example.

[0074] Furthermore, the width of the stripe pattern 210 in the mark area Mark may be the same as the width of the stripe pattern in the device area Cell; or, the width of the stripe pattern 210 in the mark area Mark may be greater than the width of the stripe pattern in the device area Cell.

[0075] In step S23, continue to refer to Figure 9a and Figure 9b As shown, a second film layer 400 is formed, and the second film layer 400 covers the top surface and the sidewall of the stripe pattern, and also covers the substrate surface between adjacent stripe patterns.

[0076] Similar to the first embodiment, the second film layer 400 can be formed by atomic layer deposition process. In addition, at least in the device region Cell, after the second film layer 400 is formed, the spacing between adjacent strip patterns can be equal or substantially equal to the width of the strip patterns.

[0077] In step S24, continue to refer to Figure 9a-9b and Figure 10a-Figure 10b As shown, a third film layer is formed by a spin coating process, wherein the coating of the third film layer fills the device area Cell and the mark area Mark, and spreads to the blank area outside the mark area, so that the height of the coating filled in the mark area Mark is lower than the height of the coating filled in the device area Cell.

[0078] It should be noted that the pattern arrangement density in the device area Cell is uniform as a whole. In particular, in order to reduce the difference in line density between the edge and the interior of the device area Cell, additional auxiliary lines are usually arranged on the periphery of the device area Cell to increase the line density at the edge of the device area Cell to ensure that the size and morphology of the film layer formed in the device area Cell are uniform. Unlike the device area Cell, the mark area Mark is set in the blank area, that is, the periphery of the mark area Mark is empty.

[0079] Thus, when the coating of the third film layer is spin-coated by the spin coating process, the coating of the third film layer 500' will be accumulated in the device area Cell due to the high pattern density and large occupied area in the device area Cell. Figure 9a and Fig.10a However, the pattern density of the marking area Mark is small and the occupied area is small, so the paint of the third film layer 500 easily spreads to the blank area outside the marking area, so that the height of the paint of the third film layer 500 in the marking area Mark is reduced, for example Figure 9b and Fig.10b shown.

[0080] Specifically, a spin coating process is performed to coat the coating of the third film layer on the substrate 100, wherein the coating height of the third film layer 500 in the mark area Mark is lower than the coating height of the third film layer 500' in the device area Cell. In this embodiment, after the spin coating process is performed, the coating of the third film layer 500' in the device area Cell fills the gap between adjacent stripe patterns, and the coating height of the third film layer 500' in the device area Cell is higher than the gap height between adjacent stripe patterns, that is, the top surface of the third film layer 500' in the device area Cell is higher than the top surface of the stripe pattern. Also, the coating height of the third film layer 500 in the mark area Mark may also be higher than the gap height between adjacent stripe patterns; or, after the spin coating process is performed, the coating of the third film layer 500 in the mark area Mark may not fill the gap between the stripe patterns, so that the coating height of the third film layer 500 in the mark area Mark is not higher than the gap height between adjacent stripe patterns, for example, the top surface of the third film layer 500 in the mark area Mark is not higher than the top surface of the stripe pattern.

[0081] For further details, please refer to Fig.10aand Fig.10b As shown, after performing the spin coating process, it also includes: performing a back etching process to reduce the coating height of the third film layer until the coating height of the third film layer 500' in the device area Cell is not higher than the gap height between adjacent stripe patterns, so that the portion of the second film layer 400 covering the stripe pattern is exposed. It should be recognized that before the back etching process, the height of the third film layer 500' in the device area Cell is higher than the height of the third film layer 500 in the mark area Mark, so after the back etching process, the height of the third film layer 500' in the device area Cell is still higher than the coating height of the third film layer 500 in the mark area Mark, then after the back etching process, the coating height of the third film layer 500 in the mark area Mark will be lower than the gap height between adjacent stripe patterns. For example, if the top surface of the third film layer 500' in the device area Cell is flush with the top surface of the second film layer 400 covering the graphic pattern, then the coating height of the third film layer 500 in the mark area Mark is lower than half of the gap height.

[0082] In step S25, refer to Fig.11a and Fig.11b As shown, an etching process is performed to remove the portion of the second film layer 400 covering the top surface of the stripe pattern and the portion between the third film layer and the stripe pattern, and also to remove the third film layer in the mark area Mark.

[0083] Similar to the first embodiment, the material of the second film layer 400 may include silicon oxide, based on which, a fluorine-containing gas may be used to etch the second film layer 400. In an optional solution, the material of the mask layer 300 may be the same as that of the second film layer 400, so when etching the second film layer 400, the exposed mask layer 300 may also be removed.

[0084] Furthermore, the third film layer will be partially consumed in the etching process. In one example, the second film layer 400 can be etched by a dry etching process, and the etching gas will bombard the third film layer at the same time during the process, so that the top of the third film layer is partially consumed. Or in other examples, the etching process used has a larger etching rate for the second film layer and a smaller etching rate for the third film layer, but the etching selectivity of the two is not much different, so that the third film layer is also consumed when etching the second film layer. In this way, the top surface of the third film layer 500' in the device area Cell can be close to the top surface of the strip pattern 210' (for example, the top surface of the strip pattern 210' is equal or close to the same height). And the third film layer 500 in the marking area Mark will be consumed in the etching process and thus removed. In this embodiment, after the third film layer 500 in the marking area Mark is removed, the exposed second film layer can be further etched, so that the second film layer in the marking area Mark is also removed.

[0085] like Fig.11a and Fig.11b As shown, in the mark area 210, the gaps between adjacent strip patterns 210 are large, so that the pattern density of the formed mark pattern is low and easy to be recognized by the device. However, the third film layer 500' in the device area Cell is still retained, and the third film layer 500' and the strip pattern 210' are used to implement a high-density patterning process. It can be seen that in this embodiment, when the pattern of the identification mark is defined by the self-aligned inverted patterning process, it can reduce the pattern density in the mark area Mark while ensuring the high-density pattern requirements in the device area Cell.

[0086] In summary, the preparation method of the identification mark provided by the present invention reduces the graphic density of the formed identification mark on the basis of being compatible with the self-aligned inverse patterning process, and improves the recognition accuracy of the identification mark by the identification device. In one optional scheme, by reducing the width of the stripe pattern in the first film layer, the stripe pattern can be automatically detached and removed in the subsequent steps, thereby reducing the graphic density of the formed identification mark. In another optional scheme, the difference between the marking area and the device area (for example, the difference in graphic density, the difference in area, etc.) is utilized to make the height of the third film layer in the marking area lower than the height of the third film layer in the device area (for example, on the basis of satisfying that the third film layer in the device area can fill the gap, the spin coating process of the third film layer is adjusted), so that the third film layer with a lower height in the marking area can be consumed in the subsequent etching process, so that the graphic density of the formed identification mark can also be reduced.

[0087] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can refer to each other. In addition, the above description is only a description of the preferred embodiment of the present invention, and is not any limitation on the scope of the present invention. For any technician familiar with the field, without departing from the scope of the technical solution of the present invention, the technical content disclosed above can be used to make many possible changes and modifications to the technical solution of the present invention, or modified into equivalent embodiments of equivalent changes. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of protection of the technical solution of the present invention.

[0088] It should also be noted that, unless otherwise specified or indicated, the terms "first", "second", "third", etc. in the specification are only used to distinguish the various components, elements, steps, etc. in the specification, rather than to represent the logical relationship or sequential relationship between the various components, elements, steps, etc. It should also be understood that the terms described herein are only used to describe specific embodiments, rather than to limit the scope of the present invention. It must be noted that the singular forms "one", "a kind of", and "the" used herein and in the appended claims include plural references unless the context clearly indicates the opposite. For example, a reference to "a step" means a reference to one or more steps, and may include secondary steps. All conjunctions used should be understood in the broadest sense. Therefore, the word "or" should be understood to have the definition of a logical "or", rather than a logical "exclusive or" definition, unless the context clearly indicates the opposite.

Claims

1. A method for preparing an identification mark used in a self-aligned inversion patterning process, characterized in that: include: Forming a first film layer in a device region and a marking region on a substrate, wherein a plurality of stripe patterns are formed in the first film layer, wherein the width of the stripe pattern in the marking region is smaller than a predetermined width, and the width of the stripe pattern in the device region is larger than a predetermined width; forming a second film layer, wherein the second film layer covers the top surface and the sidewalls of the stripe patterns, and also covers the substrate surface between adjacent stripe patterns; forming a third film layer, wherein the third film layer fills the gaps between adjacent stripe patterns and is located on the second film layer; as well as, An etching process is performed to remove the portion of the second film layer covering the top surface of the stripe pattern and the portion between the third film layer and the stripe pattern, and the stripe pattern in the marking area is peeled off from the substrate, while the stripe pattern in the device area is retained.

2. The method for preparing the identification mark according to claim 1, characterized in that: The predetermined width is no greater than 40 nm.

3. The method for preparing the identification mark according to claim 1, characterized in that: The predetermined width is half of the width of the third film layer.

4. The method for preparing the identification mark according to claim 1, characterized in that: A top surface of the third film layer is higher than a top surface of the stripe pattern.

5. The method for preparing the identification mark according to claim 1, characterized in that: Before forming the stripe pattern, an insulating layer is formed on the substrate, and after etching the second film layer, at least the insulating layer between the third film layer and the stripe pattern is exposed, and the exposed insulating layer is further etched.

6. The method for preparing the identification mark according to claim 1, characterized in that: The material of the second film layer is different from the materials of the first film layer and the third film layer.

7. A method for preparing an identification mark used in a self-aligned inversion patterning process, characterized in that: include: Providing a substrate, wherein a device area is defined on the substrate, and a marking area is defined in a blank area outside the device area; forming a first film layer in the device area and the marking area, wherein a plurality of stripe patterns are formed in the first film layer; forming a second film layer, wherein the second film layer covers the top surface and the sidewalls of the stripe patterns, and also covers the substrate surface between adjacent stripe patterns; A third film layer is formed by a spin coating process, wherein the coating of the third film layer fills the device area and the mark area and spreads to the blank area outside the mark area, so that the height of the coating filled in the mark area is lower than the height of the coating filled in the device area; as well as, An etching process is performed to remove a portion of the second film layer covering a top surface of the stripe pattern and a portion between the third film layer and the stripe pattern, and also to remove the third film layer in the marking area.

8. The method for preparing the identification mark according to claim 7, characterized in that: The forming of the third film layer by using a spin coating process comprises: Applying a coating of the third film layer by a spin coating process, wherein the coating height of the third film layer in the mark area is lower than the coating height of the third film layer in the device area, and the coating height of the third film layer in the device area is higher than the gap height between adjacent stripe patterns; and, An etch-back process is performed to reduce the coating height of the third film layer until the coating height of the third film layer in the device area is not higher than the gap height between adjacent stripe patterns, and the coating height in the mark area is lower than half of the gap height.

9. The method for preparing the identification mark according to claim 7, characterized in that: The width of the stripe pattern in the marking area is greater than the gap between adjacent stripe patterns.

10. The method for preparing the identification mark according to claim 7, characterized in that: The width of the stripe pattern in the device region is less than or equal to the gap between adjacent stripe patterns.

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