JP2012005939A - Pattern forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pattern forming method, capable of forming a pattern in an inexpensive way.SOLUTION: The method for forming a patter includes: a first step for forming, on a substrate 200, a block copolymer content film, a graft copolymer content film or a polymer mixed film, and allowing the block copolymer content film, the graft copolymer content film or the polymer mixed film to be self-organized; a second step for forming a first pattern 210 on the substrate 200 by selectively removing a plurality of polymers contained in the self-organized block copolymer content film, graft copolymer content film or polymer mixed film to leave at least one of the polymers; and a third step for attaching the first pattern 210 to a pattern forming region 102a on a film to be processed formed on a substrate 100 to be treated.

Description

  Embodiments described herein relate generally to a pattern forming method.

  In the semiconductor processing technology, development of nanoimprint technology and lithography technology using extreme ultra-violet (EUV) light is advancing as next-generation technology for producing finer patterns. However, when these techniques are incorporated into the processing process of a semiconductor device, there is a problem regarding patterning of a peripheral region (non-product region) that does not function as a product due to insufficient area.

  If the pattern coverage is different between the product (device) region and the peripheral region, the etching rate or polishing rate between the product (device) region and the peripheral region when etching or chemical mechanical polishing is performed in the process of processing the semiconductor device. Is different. For this reason, the film thickness of the substrate gradually changes in the vicinity of the boundary between both regions as the processing proceeds. In the product (device) region close to the peripheral region, the film thickness may vary even though the area is sufficient, and the product may not be commercialized. Therefore, it is necessary that the pattern coverage is substantially equal between the device region and the peripheral region.

  Therefore, in the conventional semiconductor processing technology using the optical lithography technology, the pattern (dummy pattern) similar to the product (device) region is exposed and developed in the peripheral region of the substrate, and thus the above disadvantages are caused. Has been around.

  However, in the nanoimprint technique and the EUV lithography technique, it is difficult to produce a dummy pattern due to technical problems and cost problems. In the case of nanoimprint technology, the throughput is low. In the case of EUV lithography technology, the light source is expensive and the processing cost is high. For this reason, formation of dummy patterns other than nanoimprint technology or EUV lithography technology leads to an increase in manufacturing cost.

JP 2008-210877 A

  Therefore, there is a demand for a method for forming a dummy pattern that can be used for forming a finer pattern at a low cost by using a nanoimprint technique or EUV lithography technique.

  Embodiments of the present invention have been made in view of the above, and an object thereof is to provide a pattern forming method capable of forming a pattern at low cost.

  The pattern forming method of the embodiment forms a block copolymer-containing film, a graft copolymer-containing film or a polymer mixed film on a substrate, and self-assembles the block copolymer-containing film, the graft copolymer-containing film or the polymer mixed film. Next, the plurality of types of polymers contained in the self-assembled block copolymer-containing film, graft copolymer-containing film, or polymer mixed film are selectively removed so as to leave at least one type of polymer. One pattern is formed on the substrate. Next, the first pattern is attached to a pattern forming region on a film to be processed formed on a substrate to be processed.

FIG. 1 is a plan view schematically showing a substrate 100 to be processed, which is a dummy pattern formation target in the first embodiment. FIG. 2 is a cross-sectional view schematically showing a dummy pattern forming method using the DSA according to the first embodiment. FIG. 3 is a flowchart showing a flow of a dummy pattern forming process using the DSA according to the first embodiment. FIG. 4 is a schematic diagram illustrating an example of a block copolymer film used for forming a dummy pattern according to the first embodiment. FIG. 5 is a schematic diagram showing an example of a lamellar structure in which a block copolymer film is self-organized. FIG. 6A is a cross-sectional view schematically illustrating a dummy pattern forming method using the DSA according to the second embodiment. FIG. 6B is a schematic cross-sectional view of the dummy pattern forming method using the DSA according to the second embodiment. FIG. 7 is a flowchart showing a flow of a dummy pattern forming process using the DSA according to the second embodiment.

(First embodiment)
In the first embodiment, a method for forming a dummy pattern using a DSA (Directed Self-Assembly) in a peripheral region of a semiconductor substrate on which a semiconductor device is formed will be described. Here, the peripheral region of the semiconductor substrate is a non-product region that does not function as a product (device) because an area is insufficient when a product (device) is cut out from the semiconductor substrate. In the following, a pattern forming method using DSA that can be adjusted so that the pattern coverage of the non-product area is substantially the same as the pattern coverage of the product (device) area will be described.

  FIG. 1 is a plan view schematically showing a substrate 100 to be processed, which is a dummy pattern formation target in the first embodiment. FIG. 1 is a plan view, but hatched for easy understanding. In FIG. 1, a rectangular region surrounded by a thick line indicates a product region 101 where a product (device) is formed and acquired. The product area 101 includes a product area 101 a located inside the product area 101 and a product area 101 b located on the outer peripheral side of the product area 101. In the product region 101, a circuit pattern (resist circuit pattern) is formed by a resist. The resist circuit pattern is formed using, for example, nanoimprint technology, EUV lithography technology, ArF immersion, KrF immersion, ArF, KrF, i-line, g-line exposure, and development.

  Further, the substrate to be processed 100 includes a non-product area 102 from which no product is acquired. In the non-product area 102, the peripheral area (substrate peripheral area) 102 a of the substrate 100 to be processed in which no product (device) is formed and the original product area 101, but a product ( A defective region 102b that does not function as a device is included. Hereinafter, the case where the non-product area 102 is the substrate peripheral area 102a will be described.

  Next, a dummy pattern forming method using the DSA according to the first embodiment will be described with reference to FIGS. FIG. 2 is a cross-sectional view schematically showing a dummy pattern forming method using the DSA according to the first embodiment. FIG. 3 is a flowchart showing a flow of a dummy pattern forming process using the DSA according to the first embodiment.

  First, a dummy pattern is formed using DSA outside the substrate to be processed 100. A block copolymer-containing film is formed with a substantially uniform film thickness on the entire surface of the base film 200, which is a substrate on which a dummy pattern is to be formed (step S110). That is, surface modification, surface treatment, or formation of a base film is performed so that a desired block copolymer microphase separation structure can be formed, and a block copolymer liquid is applied thereon. Of the plurality of types of polymers contained in the block copolymer-containing film, at least one type of polymer has resistance to the processing of the film to be processed which will be described later. The base film 200 is, for example, a circular shape having a size substantially the same as that of the substrate 100 to be processed.

  FIG. 4 is a schematic diagram illustrating an example of a block copolymer film used for forming a dummy pattern according to the first embodiment. In the present embodiment, as the block copolymer, a diblock copolymer composed of a polystyrene (PS) portion 212 and a polymethyl methacrylate (PMMA) portion 214 is used as shown in FIG. The molecular weight of polystyrene (PS) used in the present embodiment is 46,900, and the molecular weight of polymethyl methacrylate (PMMA) is 39,600.

  In order to form a block copolymer-containing membrane, first, 2% by weight of the block copolymer is dissolved in, for example, toluene as a solvent and filtered. Next, the filtered solution is uniformly applied to the entire surface of the base film 200 by, for example, a spin coating method to form a block copolymer-containing film.

  Next, a heating process for self-organizing the block copolymer-containing film is performed (step S120). As a heating process, after the base film 200 is baked at, for example, 220 ° C. for 1 minute to evaporate the solvent, the base film 200 is placed in an oven and baked, for example, at 180 ° C. in a nitrogen atmosphere for 8 hours. By performing the heating process, self-assembly (microphase separation) proceeds in the block copolymer-containing film, and the block copolymer film is divided into a polystyrene (PS) portion 212 and a polymethyl methacrylate (PMMA) portion 214. Then, as shown in FIG. 5, a vertical portion with a half pitch of 25 nm, in which polymethyl methacrylate (PMMA) portions 214 and polystyrene (PS) portions 212 are arranged upright alternately in layers in the in-plane direction of the base film 200. A lamella structure is formed. Thereby, the block copolymer film is formed on the entire surface of the base film 200 with a substantially uniform film thickness. FIG. 5 is a schematic diagram showing an example of a lamellar structure in which a block copolymer film is self-organized. Note that the structure in which the block copolymer film is self-organized is not limited to the vertical lamella structure, and may be another structure.

  Therefore, in the present embodiment, the base film 200 that satisfies a surface energy condition that can form a desired block copolymer microphase separation structure is used. As such a base film 200, for example, a film made of a random polymer can be used. Further, for the base film 200 that does not satisfy such conditions, surface modification, surface treatment, or formation of a base film may be performed on the surface of the base film 200 so as to satisfy the surface energy conditions as described above. Good.

  Next, anisotropic etching of the polymethyl methacrylate (PMMA) portion 214 is performed. Etching is performed, for example, by reactive ion etching (RIE) using a fluorocarbon gas and an oxygen gas. By this anisotropic etching, the polymethyl methacrylate (PMMA) portion 214 of the self-assembled block copolymer film is selectively etched, and the pattern 210 (hereinafter referred to as PS pattern 210) of the remaining polystyrene (PS) portion 212 is obtained. ) Is formed (FIG. 2A, step S130).

  Here, the PS pattern 210 is formed on the base film using a block copolymer, but a pattern may be formed on the base film in the same manner as described above using a graft copolymer instead of the block copolymer. . In place of the block copolymer, a polymer mixed film may be formed using a polymer mixture. Here, the polymer mixture is formed using a polymer mixed solution composed of a material in which PS and PMMA are dissolved in a good solvent. In addition, at least one polymer among a plurality of types of polymers contained in the block copolymer-containing film, the graft copolymer-containing film, or the polymer mixed film has resistance to processing of a film to be processed which will be described later.

  Next, a cover film 220 is stuck on the PS pattern 210 so as to cover the entire PS pattern 210 (FIG. 2B, step S140). Thereby, the dummy pattern sheet 230 in which the PS pattern 210 and the cover film 220 are laminated on the base film 200 is formed. The cover film 220 is a cover layer that is provided on the PS pattern 210 and between the PS patterns 210 so that dust or dirt does not adhere. Further, the cover film 220 functions as an adhesive layer when transferring the PS pattern 210 to the substrate to be processed 100 as will be described later. Such a cover film 220 is not particularly limited as long as it has an adhesive force capable of adhering to the PS pattern 210 and the substrate to be processed 100. For example, a normal adhesive sheet can be used for the cover film 220. Further, as the cover film 220, a sheet in which an adhesive is applied to both surfaces of a sheet having no adhesive force can be used.

  Next, the cover film 220 and the PS pattern 210 in the dummy pattern sheet 230 are formed into a predetermined shape (FIG. 2C, step S150). That is, the cover film 220 and the PS pattern 210 in the region corresponding to the product region 101 of the substrate 100 to be processed, which is an unnecessary portion, are removed while leaving the shape of the substrate peripheral region 102a. Unnecessary portions can be removed, for example, by cutting using a laser. At this time, the base film 200 is not cut off. As a result, a dummy pattern sheet 230a in which the shapes of the PS pattern 210 and the cover film 220 are formed into the shape of the substrate peripheral region 102a is formed.

  Next, a substrate to be processed 100 on which a film to be processed (not shown) such as a silicon oxide film is formed on one surface is prepared. In the product region 101 of the substrate 100 to be processed, a resist circuit pattern 110 is formed in advance on the film to be processed. Then, the dummy pattern sheet 230a is placed on the substrate to be processed 100 with the PS pattern 210 (cover film 220) facing the substrate peripheral region 102a and aligned (FIG. 2D, step S160). The PS pattern 210 is fixed to the substrate peripheral region 102 a by the adhesive force of the cover film 220. Thereafter, the base film 200 is removed (FIG. 2 (e), step S170).

  Thereafter, the lower layer is processed using the resist circuit pattern formed in the product region 101 and the dummy pattern formed in the substrate peripheral region 102a, and the semiconductor device is manufactured.

  Here, the semiconductor device can be efficiently manufactured by performing the above-described dummy pattern sheet 230a forming step and the resist circuit pattern forming step on the product region 101 in parallel.

  In the first embodiment described above, the PS pattern 210 formed in advance using DSA outside the substrate to be processed 100 as a dummy pattern is disposed in the substrate peripheral region 102 a of the substrate 100 to be processed. For this reason, it is not necessary to perform the heat processing process for the self-organization of a block copolymer with respect to the to-be-processed substrate 100. FIG. In the case where a dummy pattern is directly formed using DSA on a substrate to be processed 100 on which a resist circuit pattern has been previously formed in the product region 101, a heat treatment process for self-organization of the block copolymer is performed. To be done. This heat treatment adversely affects the resist circuit pattern. Therefore, when forming a dummy pattern directly on the substrate to be processed 100 using DSA, it is necessary to form a resist circuit pattern in the product region 101 after forming the dummy pattern first, and there is a restriction on the order of the processes. Arise.

  On the other hand, in the first embodiment described above, it is not necessary to perform a heat treatment step for self-organization of the block copolymer on the substrate 100 to be processed. For this reason, even if a resist circuit pattern is previously formed in the product region 101 of the substrate 100 to be processed, a dummy pattern can be formed in the substrate peripheral region 102a by DSA without adversely affecting the resist circuit pattern.

  Further, in the first embodiment described above, it is possible to form a dummy pattern in the same manner as described above on the substrate to be processed 100 in which the resist circuit pattern is not previously formed in the product region 101. . In this case, a dummy pattern is formed from a material insoluble in the resist. Thus, when the resist circuit pattern is formed on the product region 101 by the photolithography technique after the dummy pattern is formed, the shape of the dummy pattern is not affected even if the resist is applied by spin coating or the like. Therefore, a circuit pattern can be formed in the product region 101 without changing the coverage of the dummy pattern. The resist circuit pattern can also be produced using nanoimprint technology.

  In the first embodiment, the pattern coverage is substantially the same as the pattern coverage of the product region 101 by adjusting the ratio of each block polymer of the block copolymer film according to the pattern coverage in the product region 101. A dummy pattern can be formed in the substrate peripheral region 102a. Thereby, in etching and chemical mechanical polishing in the subsequent processing steps of the semiconductor device, processing defects due to the difference in coverage between the product region 101 and the substrate peripheral region 102a are prevented.

  When the pattern coverage is different between the product region 101 and the substrate peripheral region 102a, the etching rate and the polishing rate are different between the product region 101 and the substrate peripheral region 102a when performing etching or chemical mechanical polishing. For this reason, the film thickness of the substrate gradually changes in the vicinity of the boundary between both regions as the processing proceeds. In the product region 101b close to the substrate peripheral region 102a, although the area is sufficient, the film thickness varies, and the product cannot be commercialized, which may reduce the yield.

  However, in the first embodiment, since the coverage of the dummy pattern in the substrate peripheral region 102a can be made substantially equal to the pattern coverage of the product region 101, there is no variation in film thickness even in the product region 101b. Thereby, the product region 101b can be used as a product (device) with certainty, and the yield is improved.

  In the first embodiment, since a dummy pattern is formed using DSA without using an expensive apparatus such as an exposure machine, a fine dummy pattern can be formed at low cost.

  In the above description, the base film 200 is used as a base on which the PS pattern 210 is formed. However, the form of the base is not limited to a film. For example, a substrate-like substrate may be used. In the above description, the dummy pattern is formed using the block copolymer. However, the same effect as described above can be obtained when the dummy pattern is formed using the graft copolymer or the polymer mixture.

  In the above description, the dummy pattern sheet 230a is integrated. However, the dummy pattern sheet 230a may be divided into a plurality of base films 200 and attached to the substrate peripheral region 102a. However, from the viewpoint of alignment with the substrate peripheral region 102a, it is preferable that the dummy pattern sheet 230a is integrated.

  In the above description, the dummy pattern is formed in the substrate peripheral region 102a. However, a dummy pattern can be formed in the defective region 102b by attaching the dummy pattern sheet 230a to the defective region 102b.

(Second Embodiment)
In the second embodiment, another method for forming a dummy pattern using DSA in the peripheral region of a semiconductor substrate will be described with reference to FIGS. 6-1, 6-2, and 7. FIG. 6A and 6B are cross-sectional views schematically showing a dummy pattern forming method using the DSA according to the second embodiment. FIG. 7 is a flowchart showing a flow of a dummy pattern forming process using the DSA according to the second embodiment.

  First, the dummy pattern sheet 230 is formed by performing steps S110 to S140 in the first embodiment (FIG. 6-1 (a), step S210).

  Next, the photocurable adhesive 310 is applied to the surface of the holder 300 for holding the dummy pattern sheet 230. The holder 300 is a support member for holding the dummy pattern sheet 230. For the holder 300, a light-transmitting substrate or the like is used. Then, the dummy pattern sheet 230 is attached to the holder 300 with the photocurable adhesive 310 with the base film 200 of the dummy pattern sheet 230 facing the application surface of the photocurable adhesive 310 in the holder 300 (FIG. 6A). (B) Step S220).

  Next, the dummy pattern sheet 230 is formed into the shape of the substrate peripheral region 102a of the substrate 100 to be processed (step S230). First, the boundary between the region corresponding to the product region 101 of the substrate 100 to be processed and the region corresponding to the substrate peripheral region 102a in the dummy pattern sheet 230 is cut (FIG. 6C). The dummy pattern sheet 230 is cut using, for example, a laser.

  Next, the light L is irradiated only to the area | region corresponding to the product area | region 101 of the to-be-processed substrate 100 in the dummy pattern sheet 230 (FIG. 6-1 (d)). Thereby, the photocurable adhesive 310 in the region corresponding to the product region 101 is cured, and the adhesive force is lost. The irradiation with the light L is performed using, for example, a light shielding mask 320 in which an opening having a shape corresponding to the product region 101 of the substrate to be processed 100 is formed. Then, the hardened photocurable adhesive 310 and the dummy pattern sheet 230 in the region corresponding to the product region 101 are removed (FIG. 6-1 (e)). As a result, a dummy pattern sheet 230b is formed in which the dummy pattern sheet 230 is formed into the shape of the substrate peripheral region 102a of the substrate 100 to be processed.

  Next, a substrate to be processed 100 on which a film to be processed (not shown) such as a silicon oxide film is formed on one surface is prepared. In the product region 101 of the substrate 100 to be processed, a resist circuit pattern 110 is formed in advance on the film to be processed. Then, the PS pattern 210 (cover film 220) is opposed to the substrate peripheral region 102a and aligned, and the dummy pattern sheet 230b is placed on the target substrate 100 together with the holder 300 (FIG. 6-2 (f), Step S240). The PS pattern 210 is fixed to the substrate peripheral region 102 a by the adhesive force of the cover film 220.

  Next, light L is irradiated to the photocurable adhesive 310 through the holder 300 (FIG. 6-2 (g)). As a result, the photocurable adhesive 310 that has bonded the holder 300 and the dummy pattern sheet 230b is cured, and the adhesive force is lost. Then, the holder 300, the cured photocurable adhesive 310, and the base film 200 are removed (FIG. 6-2 (h), step S250).

  By performing the above steps, a dummy pattern composed of the PS pattern 210 can be formed in the substrate peripheral region 102a so that the pattern coverage is substantially the same as the pattern coverage of the product region 101.

  Here, a semiconductor device can be efficiently manufactured by performing the process for forming the dummy pattern sheet 230b and the process for forming the resist circuit pattern on the product region 101 in parallel.

  In the second embodiment described above, as in the first embodiment, a PS pattern 210 previously formed using DSA outside the substrate to be processed 100 as a dummy pattern is used as the substrate peripheral region 102a of the substrate 100 to be processed. To place. Thus, similarly to the first embodiment, even if a resist circuit pattern is formed in advance in the product region 101 of the substrate 100 to be processed, the DSA does not adversely affect the resist circuit pattern, so that the substrate peripheral region 102a can be obtained. A dummy pattern can be formed.

  Further, in the second embodiment described above, a dummy is formed in the same manner as described above for the substrate 100 to be processed in which the resist circuit pattern is not formed in advance in the product region 101 as in the first embodiment. It is also possible to form a pattern.

  In the second embodiment, since a dummy pattern is formed using DSA without using an expensive apparatus such as an exposure machine, a fine dummy pattern can be formed at low cost.

  In the second embodiment, the dummy pattern sheet 230 b is supported by the holder 300. Accordingly, even when the mechanical strength of the base film 200 is low, the dummy pattern sheet 230b can be easily conveyed and aligned.

  As described above, according to the above-described embodiment, it is possible to reliably and inexpensively form a dummy pattern that can be used for forming a finer pattern using a nanoimprint technique or an EUV lithography technique.

  The embodiment is not limited to the above description, and can be changed as appropriate without departing from the scope of the above processing.

  100 processed substrate, 101 product region, 101a product region, 101b product region, 102 non-product region, 102a substrate peripheral region, 102b defect region, 110 resist circuit pattern, 200 base film, 210 pattern, 212 polystyrene (PS) part, 214 Polymethylmethacrylate (PMMA) part, 220 Cover film, 230 Dummy pattern sheet, 230a Dummy pattern sheet, 230b Dummy pattern sheet, Substrate satisfying 250 surface energy, 251A Area having polymer A energy (solubility parameter), 251B Region having energy (solubility parameter) of polymer B, 251 substrate not satisfying surface energy condition, 300 holder, 310 photo-curing adhesive, 320 light shielding Mask, 252 Polymer A, 254 Polymer B, L Light.

Claims (5)

Forming a block copolymer-containing film, a graft copolymer-containing film or a polymer mixed film on a substrate;
Self-assembling the block copolymer-containing film, graft copolymer-containing film or polymer mixed film;
By selectively removing a plurality of kinds of polymers contained in the self-assembled block copolymer-containing film, graft copolymer-containing film or polymer mixed film so as to leave at least one kind of polymer, the first pattern is obtained. Forming on the substrate;
Applying the first pattern to a pattern forming region on a film to be processed formed on a substrate to be processed;
A pattern forming method comprising: Forming the first pattern into the shape of the pattern formation region and attaching it to the pattern formation region;
The pattern forming method according to claim 1. Affixing an adhesive layer on the first pattern, and affixing the first pattern to the pattern formation region by the adhesive layer;
The pattern forming method according to claim 1, wherein: Removing the substrate after pasting the first pattern together with the substrate on the pattern forming region;
The pattern forming method according to any one of claims 1 to 3. Affixing the substrate on which the first pattern is formed to a support member; and affixing the first pattern together with the support member to the pattern formation region, and then removing the support member and the substrate.
The pattern forming method according to claim 1, wherein:

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