Method for forming narrow grooves

Abstract

A method for forming a pattern on a substrate is provided. The method includes forming a first layer on a lower layer of the substrate, wherein the first layer is patterned to have a first structure. The method also includes depositing a grafted material on a side surface of the first structure, wherein the grafted material includes a solubility transfer material. The method also includes diffusing the solubility transfer material a predetermined distance into an adjacent structure adjacent to the solubility transfer material, wherein the solubility transfer material changes the solubility of the adjacent structure in a developer, and removing a soluble portion of the adjacent structure using the developer to form a second structure.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This disclosure claims the benefit of U.S. Provisional Application No. 62 / 902,434, filed on September 19, 2019, the entire contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] The present disclosure relates to microfabrication, including microfabrication of integrated circuits and processes involved in patterning semiconductor substrates. Background Art

[0004] In material processing methodologies (such as photolithography), producing a patterned layer generally involves applying a thin layer of a radiation-sensitive material (such as a photoresist) to the upper surface of a substrate. The radiation-sensitive material is converted into a patterned mask, which can be used to etch or transfer a pattern to a lower layer on the substrate. The patterning of radiation-sensitive materials generally involves exposure to the radiation-sensitive material by a radiation source through a reticle (and associated optical devices) using, for example, a photolithography system. The exposure produces a latent pattern in the radiation-sensitive material, which can then be developed. Development refers to dissolving and removing a portion of the radiation-sensitive material to produce a topography or relief pattern. For example, development can include removing an irradiated area (such as in the case of a positive photoresist) or a non-irradiated area (such as in the case of a negative resist) of the radiation-sensitive material using a developing solvent. Then, the relief pattern can be used as a mask layer. Summary of the invention

[0005] The present disclosure relates to forming patterns on substrates.

[0006] The first aspect is a method for forming a pattern on a substrate. The method includes: forming a first layer on a lower layer of the substrate, and the first layer is patterned to have a first structure. A graft material is deposited on a side surface of the first structure, and the graft material includes a solubility transfer material. The solubility transfer material is diffused a predetermined distance into an adjacent structure adjacent to the solubility transfer material, and the solubility transfer material changes the solubility of the adjacent structure in a developer. The developer is used to remove a soluble portion of the adjacent structure to form a second structure.

[0007] In some embodiments, the first structure includes a first opening of the first layer. The adjacent structure can be part of the first layer, and the first layer can include a photoresist material. The second structure includes a second opening of the first layer, wherein the latent pattern of the second opening is formed by patterned exposure of the first layer to actinic radiation prior to diffusing the soluble transfer material. In one example, the soluble transfer material renders the adjacent structure insoluble in a developer, and the first opening is spaced apart from the second opening by at least a predetermined distance. In another example, the soluble transfer material renders the adjacent structure soluble in a developer, and the first opening is connected to the second opening.

[0008] In some embodiments, the first structure includes a mandrel or a wire. The adjacent structure can be part of the first layer. Depositing the grafted material is achieved by coating the substrate with a solution having the grafted material, wherein the grafted material is deposited on all uncovered surfaces of the substrate. After diffusing the soluble transfer material, the method can also include removing the grafted material from the substrate and depositing a photoresist material on the substrate to form a latent pattern of a second structure, wherein the photoresist material is adjacent to the first structure. For example, the soluble transfer material can make the adjacent portion of the fill material soluble in a developer, and the first structure can be spaced at least a predetermined distance from the second structure.

[0009] In some embodiments, the first structure includes a mandrel or wire and the adjacent structure may be a photoresist material deposited on the substrate after depositing the grafted material.

[0010] The second aspect is a method for forming a pattern on a substrate. The method includes: forming a patterned first layer on a lower layer of the substrate, wherein the patterned first layer includes a first material, and the lower layer includes a second material that is chemically different from the first material. The patterned first layer has a first structure. A grafted material is deposited on the substrate, and the grafted material selectively adheres to the uncovered surface of the first structure. The grafted material includes a soluble transfer material. A filling material is deposited on the substrate, and the filling material is adjacent to the grafted material. The soluble transfer material diffuses a predetermined distance into the adjacent portion of the filling material, and the soluble transfer material changes the solubility of the adjacent portion of the filling material in a developer. The soluble portion of the filling material is removed using a developer so that the remaining portion of the filling material forms a second structure.

[0011] In some embodiments, the solubility transfer material renders the adjacent portion of the fill material soluble in the developer, and the first structure is spaced at least a predetermined distance from the second structure. In alternative embodiments, the solubility transfer material renders the adjacent portion of the fill material insoluble in the developer, and the first structure is in contact with the second structure.

[0012] In some embodiments, the solubility transfer material includes a thermal acid generator, and the method may further include activating the thermal acid generator by heat before diffusing the solubility transfer material into the filler material. In some embodiments, the solubility transfer material includes a photoacid generator, and the method may further include activating the photoacid generator by actinic radiation before diffusing the solubility transfer material into the filler material. For example, actinic radiation may be performed using a photomask so that the solubility transfer material is activated by patterned exposure of actinic radiation. In some embodiments, the solubility transfer material includes a base that neutralizes the acid.

[0013] In some embodiments, the fill material includes a photoresist material. The method may also include forming a latent pattern of the second structure in the photoresist material via patterned exposure to actinic radiation before diffusing the soluble transfer material into the fill material. In some examples, the latent pattern may overlap with an adjacent portion of the photoresist material.

[0014] In some embodiments, the first structure comprises a mandrel or a wire. Prior to depositing the grafting material on the substrate, the mandrel or wire may be hardened.

[0015] The third aspect is a method for forming a pattern on a substrate. The method includes: forming a patterned first layer on a lower layer of the substrate, and the patterned first layer has a first structure. Depositing a grafted material on the substrate, and the grafted material selectively adheres to the uncovered surface of the first structure, resulting in a predetermined thickness of the grafted material on the sidewall of the first structure. Forming a second structure on the substrate by a photoresist, and the second structure is adjacent to the grafted material. Removing the grafted material so that the first structure is spaced apart from the second structure by a distance corresponding to the predetermined thickness. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] When with Figure 1 The various aspects of the present disclosure are best understood from the following detailed description when read together. Note that, in accordance with standard practice in the industry, various features are not drawn to scale. In fact, the size of various features may be increased or reduced for clarity of discussion.

[0017] Figure 1 is a flow chart of a method of forming a pattern on a substrate according to some embodiments of the present disclosure.

[0018] Figure 2 is a flow chart of a method of forming a pattern on a substrate according to some embodiments of the present disclosure.

[0019] Figure 3 A. Figure 3 B. Figure 3 C. Figure 3 D. Figure 3 E and Figure 3A', Figure 3 B', Figure 3 C', Figure 3 D'and Figure 3 E' shows schematic cross-sectional and top views of a substrate at various intermediate steps of forming a pattern using a thermal acid generator (TAG) according to an embodiment of the present disclosure.

[0020] Figure 4 A. Figure 4 B. Figure 4 C. Figure 4 D. Figure 4 E. Figure 4 F and Figure 4 A', Figure 4 B', Figure 4 C', Figure 4 D', Figure 4 E' and Figure 4 F' shows schematic cross-sectional and top views of a substrate at various intermediate steps of forming a pattern using a photoacid generator (PAG) according to an embodiment of the present disclosure.

[0021] Figure 5 A. Figure 5 B. Figure 5 C. Figure 5 D. Figure 5 E. Figure 5 F. Figure 5 M. Figure 5 N. Figure 5 P. Figure 5 Q and Figure 6 A. Figure 6 B. Figure 6 C. Figure 6 D. Figure 6 E. Figure 6 F. Figure 6 M. Figure 6 N, Figure 6 P. Figure 6 Q and Figure 7 A. Figure 7 B. Figure 7 C. Figure 7 D. Figure 7 M. Figure 7 N. Figure 7 P. Figure 7 Q and Figure 8 A. Figure 8 B. Figure 8 C. Figure 8 D. Figure 8 M and Figure 8 N shows an embodiment of using a functional grafted material to create gaps or connections between structures or openings regardless of overlay errors or lithographic misalignment according to an embodiment of the present disclosure.

[0022] Fig. 9 A. Fig. 9 B. Fig. 9 C. Fig. 9 D. Fig. 9 E. Fig. 9 F and Fig. 9 A', Fig. 9 B', Fig. 9 C', Fig. 9 D', Fig. 9 E' and Fig. 9 F' shows schematic three-dimensional (3D) and top views of a substrate at various intermediate steps of pattern formation according to an embodiment of the present disclosure.

[0023] Fig.10 A. Fig.10 B and Fig.10 C shows the Fig. 9 An example of a process for forming a pattern on a substrate.

[0024] Fig.11 is a flow chart of a method of forming a pattern on a substrate according to an embodiment of the present disclosure.

[0025] Fig.12 A. Fig.12 B. Fig.12 C. Fig.12 D. Fig.12 E and Fig.12 F shows schematic 3D and top views of a substrate at various intermediate steps of pattern formation according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0026] The following disclosure provides many different embodiments or examples for realizing the different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. Of course, these are examples only and are not intended to be limiting. For example, in the following description, a first feature formed above or on a second feature may include an embodiment in which the first feature and the second feature are formed as direct contact, and may also include an embodiment in which an additional feature may be formed between the first feature and the second feature so that the first feature and the second feature may not be in direct contact. In addition, the present disclosure may repeat reference numerals and / or letters in various examples. This repetition is for the purpose of simplicity and clarity, and does not itself indicate the relationship between the various embodiments and / or configurations discussed. In addition, spatially relative terms such as "top", "bottom", "below", "below", "lower", "above", "upper", etc. may be used herein to facilitate description of the relationship between an element or feature as shown in the figure and another element or feature. In addition to the orientations depicted in the figure, spatially relative terms are intended to cover different orientations of the device in use or operation. The device may be oriented (rotated 90 degrees or in other orientations) in other ways, and the spatially relative descriptors used in this article may be interpreted accordingly.

[0027] For the sake of clarity, the order of discussion of the different steps described herein has been presented. Generally, these steps can be performed in any suitable order. In addition, although each of the different features, techniques, configurations, etc. herein can be discussed in different places of the present disclosure, it is expected that each of the concepts can be performed independently of each other or in combination with each other. Therefore, the present invention can be implemented and viewed in many different ways.

[0028] One approach to printing features at sub-resolution pitches is to split the pattern between two masks with a relaxed pitch and reassemble in consecutive lithography and etching steps. However, this approach can suffer from overlay errors and edge placement errors (EPE). One disadvantage of this approach is that splitting the pattern into two exposures and etchings reduces yield. The second disadvantage is multi-pattern misalignment. Anti-spacers are self-aligned processes that are not resolution-limited, which solves both challenges at the same time. In addition, similar techniques described herein for anti-spacer formation can be used for "snap to" and "snap away" techniques. The snap technique also mitigates the effects of overlay on edge collection by using active materials.

[0029] The anti-spacer technology uses the diffusion length of the active material to define the critical dimension (CD), thereby producing, for example, narrow grooves or groove contacts. The CD can be adjusted by changing the molecular weight of the active material, the molecular structure of the active material, and the baking temperature / time. If the active material can be spatially controlled by exposure through a mask or selective deposition, a narrow groove contact can be formed instead of a narrow groove. Another way to produce a narrow groove contact is to use a holding / cutting mask after forming the narrow groove. However, this technology introduces another lithographic exposure and film stack. In the present disclosure, for ease of explanation, the examples will focus on the use of acids as active materials.

[0030] The technology herein includes a process flow for patterning a substrate using the diffusion length of a soluble transfer material to form narrow grooves or provide a buffer (i.e., forming a slot contact) between adjacent structures or openings. The technology herein includes forming a patterned first layer having a first structure, depositing a graft material including a soluble transfer material on a side surface of the first structure, diffusing the soluble transfer material into an adjacent structure, and removing a soluble portion of the adjacent structure. By controlling the diffusion conditions and duration, sub-resolution CD can be defined and utilized for "fast grab to" and "fast grab off" techniques.

[0031] Figure 1 1 is a flow chart of a method 100 for forming a pattern on a substrate according to some embodiments of the present disclosure. The method 100 begins with step S101, in which a first layer is formed on a lower layer of the substrate, and the first layer is patterned to have a first structure. The first structure may, for example, include a mandrel / wire of the first layer (e.g. Figures 3 to 6 and Figures 9 and 10 ) or opening (e.g. Figures 7 and 8 ).

[0032] At step S102, a graft material including a soluble transfer material is deposited on the side surface of the first structure. In some embodiments, the graft material selectively adheres to the uncovered surface of the first structure line (e.g. Figures 3 to 6 In other embodiments, the grafted material is non-selectively deposited on all uncovered surfaces of the substrate (e.g. Figures 7 to 10 For example, the grafted material may be deposited on the side and bottom surfaces of the opening and on the top surface of the patterned first layer (eg Figures 7 and 8 In another example, the grafted material may be deposited on the side and top surfaces of the mandrel and the top surface of the underlying layer (eg, Figures 9 and 10 ).

[0033] At steps S103 and S104, the solubility transfer material is diffused a predetermined distance into an adjacent structure adjacent to the solubility transfer material, and then a developer is used to remove the soluble portion of the adjacent structure to form a second structure. The solubility transfer material is designed to change the solubility of the adjacent structure in a particular developer. In some embodiments, the solubility transfer material makes the adjacent structure soluble in a particular developer so that the first structure is spaced apart from the second structure by at least a predetermined distance (e.g., Figures 3 to 6 and Figures 9 and 10 In some embodiments, the soluble transfer material renders the adjacent structure insoluble in a particular developer, such that a first structure is brought into contact with a second structure (eg, Figures 5 and 6 In some embodiments, the soluble transfer material renders the adjacent structure soluble in a particular developer, allowing the first structure to contact the second structure (eg, Figures 7 and 8 In some embodiments, the soluble transfer material renders adjacent structures insoluble in a particular developer such that a first structure is spaced at least a predetermined distance from a second structure (eg, Figures 7 and 8 ). In addition, in some embodiments, the soluble transfer material may be activated before step S103.

[0034] Still referring to step S103 and step S104, in the example where the first structure is an opening of the first layer, the adjacent structure is a portion of the first layer (eg Figures 7 and 8 Thus, the second structure may be a second opening spaced apart from or in contact with the first opening. In another example where the first structure is a mandrel or a wire, the adjacent structure may be a portion of the first layer (e.g. Figures 9 and 10 ) or a layer of photoresist material deposited on the substrate after the grafting material is deposited (e.g. Figures 3 to 6 In fact, the method 100 includes at least eleven implementations (eg, Figures 3 to 10 ), each of which will be described in detail later.

[0035] Figure 2 is a flow chart of a method 200 for forming a pattern on a substrate according to some embodiments of the present disclosure. The method 200 may include Figure 1 At least six embodiments of the method 100 (e.g. Figures 3 to 6 ). At step S201, a patterned first layer is formed on a lower layer of a substrate. The patterned first layer includes a first material, and the lower layer includes a second material that is chemically different from the first material. The patterned first layer may also have a first structure, such as a mandrel or a wire. For example, the mandrel may be made of a first photoresist material. Note that the discussion of method 200 will focus on the first photoresist material and the mandrel, but the first material may also be a hard mask material, and the first structure may include other structures.

[0036] At step S202, a graft material including a solubility transfer material is deposited on a substrate, wherein the graft material selectively adheres to the uncovered surface of the first structure. A graft material (also referred to as a brush) is a polymer or short-chain polymer having a linking group. Based on the selected specific head group, the graft material can be attached to the surface of a specific material without being attached to the surface of other materials. The graft material can be a self-assembled monolayer (SAM). In some embodiments, the graft material is preferably more polymerized than that prepared with a hydrocarbon chain. The graft material can be applied via spin coating deposition, physical vapor deposition or other means. In some embodiments, after depositing a specific graft material, a baking process is performed. Baking bonds the graft material to the first photoresist material without bonding to the lower layer. Unbonded materials (e.g., bottom plate materials) can then be removed using a solvent stripping process. The other side of the graft material can include a functional group, such as a thermal acid generator (TAG), a photoacid generator (PAG), a base, or another solubility transfer material.

[0037] At step S203, a filling material is deposited on the substrate, wherein the filling material is adjacent to the grafted material. For example, an outer coating of the filling material can be deposited on the patterned first layer. The filling material can be a second photoresist material or another filling material responsive to the solubility transfer material. In some embodiments, the filling material is substantially selected to react with an acid to become soluble in a developer. An example of a filling material primarily used in the present disclosure is a polymer with a protective group that reacts with an acid to become soluble in a given developer.

[0038] At step S204, the solubility transfer material diffuses a predetermined distance into the adjacent portion of the filling material, so that the solubility transfer material changes the solubility of the adjacent portion of the filling material in a specific developer. At step S205, the soluble portion of the filling material is removed using a developer, so that the remaining portion of the filling material forms a second structure. In some embodiments, the solubility transfer material makes the adjacent portion of the filling material soluble in the developer. Therefore, the first structure is spaced apart from the second structure by at least a predetermined distance. In other embodiments, the solubility transfer material makes the adjacent portion of the filling material insoluble in the developer, so that the first structure is in contact with the second structure. In addition, in some embodiments, an activation step of activating the solubility transfer material can be performed before step S204.

[0039] Figure 3 Schematic cross-sectional views and top views of a substrate 300 at various intermediate steps of pattern formation using TAG according to an embodiment of the present disclosure are shown. In particular, Figure 3 A method for forming narrow grooves and trench contacts using a grafted material having a functional group of TAG is shown and may be Figure 2Therefore, some descriptions have been provided above, and these descriptions will be omitted here for the purpose of simplicity.

[0040] Figure 3 A' to Figure 3 E' is a top view of the substrate 300, and Figure 3 A to Figure 3 E is the corresponding cross-sectional view taken along the line cutting Aa to Ee in the z direction. Figure 3 As shown in FIG. 1A , a patterned first layer 310 is formed on a lower layer 301 of a substrate 300 . The patterned first layer 310 includes a first structure, such as a mandrel 311 . For example, Figure 3 A and Figure 3 A' may show the topographic pattern formed after exposure and development of the first photoresist layer. Note that photoresist is used herein as the main example, but the initial pattern may be photoresist or other materials such as hard mask material.

[0041] exist Figure 3 B and Figure 3 In B', the graft material 321 is selectively deposited on the uncovered surface of the mandrel 311. Therefore, the graft material 321 adheres to the top surface 311' and the side surface 311" of the mandrel 311, but does not adhere to the uncovered top surface 301' of the lower layer 301. Figure 2 In the grafting material of step S202, the grafting material 321 includes TAG as an exemplary soluble transfer material.

[0042] exist Figure 3 C and Figure 3 In C', a filling material 331 is deposited on the substrate to form an outer coating on the mandrel 311. Similarly, the filling material 331 can be a polymer with a protective group that reacts with an acid to become more soluble in a given developer. Spin coating is a common way to deposit such an outer coating, and the resulting outer coating will generally not only fill the space, but also completely cover the first patterned first layer. The outer coating can be planarized (flat as shown) or non-planarized (not shown). In addition, the filling material should be effectively free of solubility transfer material, which means that the filling material does not include a solubility transfer material or includes a solubility transfer material in an amount insufficient to reduce the solubility change.

[0043] exist Figure 3 D and Figure 3In D', the TAG included in the grafted material 321 is diffused a predetermined distance into the adjacent portion 341 of the filling material, so that the TAG changes the solubility of the adjacent portion of the filling material in the developer. In some embodiments, a baking step is performed, which diffuses the acid into the filling material 331, thereby making the diffused portion 341 soluble. After the acid reacts with the filling material 331 to a selected distance, the substrate 300 can be baked at a higher temperature to decompose the crosslinker in the mandrel 311, thereby further reducing the solubility of the mandrel 311. For example, the post-exposure bake (PEB) for a particular resist can be about 90°C, and the TAG can be activated and diffused between 120°C-130°C. A given crosslinker can be activated with a bake of 150°C-160°C. In some embodiments, a TAG that does not decompose during the PEB of the initial pattern formation (i.e., the patterned first layer 310) should be selected. According to some embodiments, the crosslinker should not be decomposed until after the PEB and TAG are baked.

[0044] In this example, the TAG renders the adjacent portion 341 of the filler material soluble in the developer. Figure 3 E and Figure 3 E' removes the adjacent portion 341 of the fill material. Specifically, a development step is performed to remove the soluble portion 341 (i.e., the adjacent portion) of the fill material. This leaves a narrow groove 351 on the sidewall 311" of the mandrel 311, so that the first structure (i.e., the mandrel 311) is spaced apart from the second structure (i.e., the remaining fill material 331) by at least a predetermined distance. Any subsequent patterning can then continue, such as masking a portion of the narrow groove for selective transfer to an underlying layer.

[0045] Figure 4 Schematic cross-sectional and top views of a substrate 400 are shown at various intermediate steps of pattern formation using PAG according to an embodiment of the present disclosure. Figure 3 similar, Figure 4 A method of forming narrow grooves and trench contacts using a grafted material having a functional group that is a PAG is shown, and may also be Figure 2 Compared to TAG, PAG is more thermally stable and can provide spatial control via controlled exposure to actinic radiation.

[0046] Similarly, Figure 4 A' to Figure 4 F' is a top view of the substrate 400, and Figure 4 A to Figure 4 F is a corresponding cross-sectional view taken along a line cutting A'a' to E'e' in the z direction. Figure 4 A and Figure 4 A′ shows a patterned first layer 410 with mandrels 411 on the underlying layer 401 . Figure 4 B and Figure 4 B′ shows the attachment of the grafted material 421 including PAG to the mandrel 411 . Figure 4 C and Figure 4 C' shows an outer coating 431 of filler material. Figure 4 D and Figure 4 In D', a patterned photolithography exposure is performed, wherein a photomask 441 is positioned on the substrate 400. The arrows represent incident light, such as ultraviolet light. Figure 4 E and Figure 4 In E', the baking step causes the acid generated by the exposure to diffuse a predetermined distance into the filling material 451. The predetermined distance is a function of the amount of acid generated, the baking time, and the baking temperature (for example), and thus the distance can be precisely controlled. Figure 4 F and Figure 4 F' shows the formation of narrow grooves 461 (eg, narrow trenches) after the development step.

[0047] Figures 5 to 8 Embodiments are shown for using functional grafted materials (e.g., TAG, PAG, or base) to create gaps (e.g., narrow trenches) or connections (e.g., trench contacts) between structures or openings regardless of overlay errors or lithographic misalignment, which may be Figure 2 Therefore, some descriptions have been provided above, and these descriptions will be omitted here for the purpose of simplicity.

[0048] Figure 5 Schematic 3D and top views of a substrate 500 are shown at various intermediate steps of pattern formation according to some embodiments of the present disclosure. Figure 5 A shows a patterned line (structure) 511 formed on the lower layer 501 of the substrate 500, which corresponds to the first structure in the method 200. In this example, the line 511 is made of a first photoresist material and is formed by photolithography. The line 511 can be developed using a positive developer (PTD). After formation, a direct current superposition (DCS) processing step can be performed to harden the photoresist line 511 to prevent it from becoming soluble. DCS can be achieved in a plasma chamber by coupling a negative DC power to the upper electrode of the plasma chamber to generate a ballistic electron flow that strikes the substrate 500. As a result, the physical properties of the exposed surface of the line 511 (including the top surface 511' and the two side surfaces 511") change, become insoluble in the solvent, and form a new film 513 around the line 511. Crosslinking can occur within the film 513 during the DCS process. In addition, other processes such as thermal freezing, gas freezing, etc. can also be used.

[0049] Next in Figure 5In B, a graft material 521 having an acid functional group is coated on the wire 511 (or more precisely, on the membrane 513). Figure 5 A second photoresist material 531 may be deposited in C. Figure 5 In D, substrate 500 is exposed to a second pattern of actinic radiation. Actinic radiation (represented by arrows) is applied by a photomask 543 positioned on substrate 500 so that a potential second pattern (not shown) is formed in second photoresist material 531. The acid functional group is then activated and diffused into second photoresist material 531 at a predetermined distance to form diffusion layer 541. In diffusion layer 541, acid changes the solubility of second photoresist 531 that has received enough acid. In this article, acid makes diffusion layer 541 soluble. In an embodiment where the acid functional group is TAG, a baking step is performed for activation and diffusion. In another embodiment where the acid functional group is PAG, actinic radiation (e.g., full exposure or patterned exposure at a specific wavelength where the second photoresist material 531 is opaque) is performed for activation and subsequent baking for diffusion.

[0050] exist Figure 5 In E, the second pattern is developed, for example, using PTD, to remove the soluble portion of the second photoresist layer 531 including the diffusion layer 541. Therefore, the second structure 551 is formed by the remaining insoluble second photoresist material 531. In addition, a gap 553 is formed between the first structure 511 and the second structure 551. In some embodiments, as Figure 5 As shown in F, the grafted material 521 may be removed to further widen the gap 553 .

[0051] Figure 5 M and Figure 5 N is Figure 5 D and Figure 5 Top view of E. Figure 5 In M, arrows indicate diffusion processes, while dashed lines indicate Figure 5 The area in D that is exposed to actinic radiation, and represented by 533 as the latent pattern, will eventually become the second structure 551. Figure 5 M shows that even if the exposure (i.e., the dashed area) is misaligned so that the lines (i.e., 513 and 533) are too close together, the diffusion from the grafted material 521 (i.e., 541) substantially shortens the second line 533 close to the first line 513 to "snap away" from the first line 513. In other words, in this embodiment, the acid diffuses into the second line 533 to ensure that the second line 533 is close to the first line 513. Figure 5 There is a gap 553 in N. This can provide a number of patterning benefits, such as preventing short circuit current paths between structures.

[0052] Figure 5 P and Figure 5Q is respectively and Figure 5 D and Figure 5 E is a top view of a structure similar to that of FIG. This embodiment is similar to FIG. 5 except that the grafting material 521 includes a base rather than an acid generator. Figure 5 A to Figure 5 F. The alkali in the PTD that removes the soluble portion of the second photoresist layer 531 makes the diffusion layer 541 insoluble. Note that Figure 5 In FIG. 5M, although the exposure 551 of the second line (ie, the latent pattern 533) fails to reach the first line 513, the first line 513 becomes substantially wider after diffusion (ie, 541), so that the two lines are in contact without a gap separating them.

[0053] Figure 6 Schematic 3D and top views of a substrate 600 at various intermediate steps of pattern formation according to other embodiments of the present disclosure are shown. Figure 6 Similar to Figure 5 , so the differences will be explained emphatically. Herein, a reverse photomask 643 is used so that the photomask 643 and the photomask 543 complement each other. That is, in the current embodiment, the exposure area of ​​the photomask 543 is the blocking area of ​​the photomask 643, and the exposure area of ​​the photomask 643 is the blocking area of ​​the photomask 543. In addition, the second photoresist material 631 is negative rather than positive.

[0054] Figure 6 M and Figure 6 N is respectively according to one embodiment of forming a "quick grab away" structure Figure 6 D and Figure 6 E. Similarly, in Figure 6 In M, arrows indicate the diffusion process, while the dashed area indicates Figure 6 The area in D exposed to actinic radiation and the latent pattern is represented by 633, which will eventually become the second structure 651. In this embodiment, the grafting material 621 includes a base (which can neutralize excess acid). The first line 611 is developed using PTD, while the second line 651 is developed using NTD. After exposure, note that Figure 6 In the embodiment of FIG. 6A , the latent pattern 633 may extend to the grafted material 621 (so that the two lines will touch), but then diffusing the base away from the first line 613 may neutralize the acid in the latent pattern of the second line 633, so that this material (i.e., the diffusion layer 641) remains insoluble in the NTD and can be subsequently removed to ensure that Figure 6 A gap 653 between the first line 613 and the second line 651 in N.

[0055] Figure 6 P and Figure 6 Q is respectively and Figure 6 D and Figure 6 E is a top view of a similar structure. In this embodiment, the grafted material 621 includes an acid functional group (e.g., TAG or PAG). The first line 611 can be developed by PTD or NTD, and the second line 651 can be developed by NTD. Similarly, the bonding of the structure can be ensured despite the overlay error. A latent pattern 633 is formed in a second photoresist 631 deposited on the substrate 600. Then, the diffusion from the first line 613 (i.e., 641) ensures that the two lines are bonded. In other words, in the current embodiment, the acid can diffuse from the first line 611 to make the area 641 around the first line insoluble in NTD. After the second line 651 is developed, the first line 611 and the second line 651 are bonded. In the absence of a diffusion step, the result would be that there would be a gap between the two structures.

[0056] Figure 7 and Figure 8 Shown is a structure having openings (e.g., grooves) rather than Figure 5 and Figure 6 The "quick snap to" and "quick snap off" configurations of the wires shown. Figure 7 Schematic 3D and top views of a substrate 700 at various intermediate steps of pattern formation according to other embodiments of the present disclosure are shown. As shown, a first trench 711 is imaged between two lines 713 within a patterned first layer 710 on a lower layer 701 of the substrate 700, and the first trench 711 is then coated with a grafted material 721 having a base functional group. Note that the grafted material 721 can be non-selectively deposited on all uncovered surfaces, including the sidewalls 711", the bottom surface 711' of the first trench 711, and the top surface 713' of the line 713. Optionally, a spacer opening etch can be performed. This is a directional etch that removes the grafted material 721 from horizontal surfaces (i.e., the bottom surface 711' of the first trench 711 and the top surface 713' of the line 713), leaving sidewall (i.e., 711") deposits in the first trench 711 (not shown). Subsequently, the actinic radiation, diffusion, and development processing steps are performed in conjunction with the step of forming the first trench 711. Figure 5 and Figure 6 The corresponding steps in are similar, but Figure 7 The diffusion layer is not shown in C. Thus, the second trench 741 is formed and is spaced apart from the first trench 711 by the region 743 of the line 713 .

[0057] Figure 7 M and Figure 7 N is respectively according to one embodiment of forming a "quick grab away" structure Figure 7 C and Figure 7 Top view of D. Figure 7 In M, arrows indicate the diffusion process, while the dashed area indicates Figure 7 The areas in C that are exposed to actinic radiation, and the latent pattern is represented by 733, which will eventually become the second structure 741. In this embodiment, a grafted material 721 with a base is used. Figure 7 M and Figure 7 N shows an exposure with an overlay error that causes the first and second trenches (i.e., 711 and 741) to merge. That is, the latent pattern 715 generated by the actinic exposure of the photomask 731 is in contact with the grafted material 721 covering the first trench 711. However, the diffusion (i.e., 743) from the grafted material 721 makes the area 743 between these trenches insoluble, so that the two trenches are separated after development. In addition, the first trench 711 and the second trench 741 can be formed using PTD.

[0058] Figure 7 P and Figure 7 Q is respectively and Figure 7 C and Figure 7 The structure of D is similar to the top view of the structure. Similarly, the arrows indicate the diffusion process, and the dashed area indicates Figure 7 The areas in C that are exposed to actinic radiation, and the latent pattern is represented by 733, which will eventually become the second structure 741. In this embodiment, a grafted material 721 with an acid is used instead of a grafted material 721 with a base. Figure 7 P shows that the latent pattern 733 is not in contact with the first trench 711. The acid from the grafted material 721 diffuses, making the separated portion 743 of the photoresist soluble, so that the two trenches are in contact after development. That is, in this embodiment, according to the dotted area defined by the photomask 731, the latent pattern 715 is spaced apart from the first trench 711. However, the acid from the grafted material 721 diffuses a predetermined distance to effectively "widen" the first trench 711 to ensure that the first trench 711 and the second trench 741 merge. In addition, the first trench 711 and the second trench 741 can be formed using PTD.

[0059] Figure 8 Schematic 3D and top views of a substrate 800 at various intermediate steps of pattern formation are shown according to other embodiments of the present disclosure. Figure 8 Shown with Figure 7 A similar process is performed, but using a reverse light pattern, as shown in reverse photomask 831. Thus, PTD can be used for developing the first trench (711), and NTD can be used for developing the second trench (741). Other descriptions have been provided above and will be omitted here for the sake of simplicity. Note that although Figure 8Only an embodiment is shown in which a "quick grab in" structure is formed, but it should be understood that a "quick grab off" structure can also be formed using the reverse light pattern.

[0060] Fig. 9 An additional embodiment of using pickling to form narrow grooves is shown, which may be Figure 1 An implementation of method 100 in . Fig. 9 A' to Fig. 9 F' is a top view of substrate 900 at various intermediate steps of the example method, and Fig. 9 A to Fig. 9 F is the corresponding cross-sectional view taken along the line cutting A"a" to F"f" in the z direction. The pickling flow is a three-material process where the active material is driven into the mandrel by soaking the substrate in a solution of the active material to produce self-aligned double patterning (SADP).

[0061] like Fig. 9 A and Fig. 9 As shown in A', substrate 900 includes a patterned first layer 910 on a lower layer 901. In this example, patterned first layer 910 includes lines 911 made of a first photoresist material. Fig. 9 B and Fig. 9 In B', after forming the photoresist line 911, acid is deposited on the substrate 900. Fig. 9 C and Fig. 9 In C', a baking step may be performed to activate the deprotection in the deprotected regions 931 by diffusing the acid into the lines 911. This makes a certain thickness of the lines (i.e., the deprotected regions 931) soluble in a given developer. A solvent rinse step is then required to remove any residual acid. Then, in Fig. 9 D and Fig. 9 In D', a fill material 941 such as a second photoresist material is deposited. The fill material 941 should be compatible with the first photoresist solvent system in such a way that after the fill material 941 is deposited, for example by a typical spin coating process, the deprotected areas 931 and lines 911 remain on the substrate 900. Fig. 9 E and Fig. 9 In E', the filling material 941 is also designed to allow the cover layer to be removed. Fig. 9 F and Fig. 9 As shown in F', the soluble material 931 may then be developed, leaving a narrow trench 961 between the line 911 (first structure) and the remaining fill material 941 (second structure).

[0062] Fig.10 Shown according to Fig. 9 An example of a process for forming a pattern on a substrate. Fig.10It is shown how two patterns can be formed on a substrate while maintaining a sufficient distance between the structures. Fig.10 This embodiment is shown using an acid wash to ensure that the structures do not merge, but a grafted material may also be used to ensure that overlay errors do not cause the structures to join.

[0063] In this method, the pattern is divided into two masks and recombined in consecutive lithography and etching steps, and the line or space width is defined by the edge placed at the separated mask. The benefit of the technology in this article is that the impact of errors is minimized by diffusion-based buffering and suitable resists. In the automatic double pattern lithography (DPL) design flow, the decomposition of the layout for multiple exposure steps is a challenge. There is a challenge to identify the best cutting point on the polygon. Therefore, the technology in this article can overcome the challenges faced in layout decomposition or pattern stitching.

[0064] In this method, a trade-off between the overlay problem caused by the resolution limit of the lithographic Raleigh criterion and the sub-resolution trenches caused by acid diffusion is applied to solve the post-layout decomposition problem. The shuffled pattern overlap caused by closely adjacent exposures can be prevented by using acid-diffused spin-on materials and two-layer patterning.

[0065] Fig.10 A is used Fig. 9 1000 after patterning. As shown in the figure, in order to generate a conflict-free layout (i.e., a layout that ensures sufficient distance between structures), an initial photoresist pattern L1 is printed on the substrate 1000 (L1 is represented by the area defined by the dotted line). The printed pattern L1 is then coated with an acid wash solution (e.g. Fig. 9 B) After coating the initial photoresist pattern L1 with an acid wash and baking to activate the deprotection in the deprotected areas, a solvent rinse step is used to remove any residual acid (e.g. Fig. 9 C). Thus, the remaining photoresist pattern L1 forms line 1010. The pattern L1 (eg, Fig. 9 D). The L2 material must be compatible with the L1 photoresist solvent system. The L2 material is designed in such a way that when the L2 layer lacks a topcoat (i.e., Fig. 9 E), the outer coating area is removed as a result of the development loss of L2. Note that factors in the L2 design are the dissolution rate for both the ability to remove the outer coating area of ​​L2 during L2 development and how much feature shrinkage will occur during L2 development. This technique can be more successful with consistency in the height distribution for L2 loss from no top coating exposure and L1 diffusion length (e.g. Fig. 9F). Development loss is measured as the difference in thickness of the L2 material before and after development. Development loss is designed to be equal to the diffusion loss due to pickling. The diffusion region is defined with sub-resolution grooves (e.g. Fig. 9 In the gap region of the groove 961 in F, the resolution is limited by the acid diffusion length of about 7 nm.

[0066] Fig.10 B is Fig.10 A is a magnified view of circle CirA, and Fig.10 C is a cross-sectional view taken along the line cutting gG in the z direction. Fig.10 B and Fig.10 C also shows the gap region between line 1010 (L1) and line 1020 (L2). In particular, the width D of the gap region represents the predetermined diffusion length of the acid during the baking process. Introducing pickling to produce a deprotected laminar flow by pattern decomposition is a unique way to reduce the overlay error caused by close proximity interactions. Therefore, the goal of this article helps to reduce the overlay error caused by the resolution limit of the Rayleigh criterion. This can be used for sub-resolution grooves. The resolution is limited by the acid diffusion length of about 7nm.

[0067] Fig.11 1 is a flow chart of a method 1100 for forming a pattern on a substrate according to an embodiment of the present disclosure. The method 1100 begins with step S1101, in which a patterned first layer is formed on a lower layer of the substrate. The patterned first layer has a first structure. At step S1102, a grafted material is deposited on the substrate so that the grafted material selectively adheres to an uncovered surface of the first structure, thereby forming a grafted material of a predetermined thickness on the sidewall of the first structure. At step S1103, a second structure adjacent to the grafted material is formed on the substrate by a photoresist. Then, the method 1100 proceeds to step S110, in which the grafted material is removed so that the first structure is spaced apart from the second structure by a distance corresponding to the predetermined thickness.

[0068] Fig.12 Schematic 3D and top views of a substrate 1200 at various intermediate steps of pattern formation according to some embodiments of the present disclosure are shown. Fig.12 1211, but a DCS treatment may also be performed to harden the wire 1211 to prevent it from becoming soluble and to form a film covering the wire 1211, as already described in Figure 5 As shown in Fig.12 Example implementation of the process flow in Figure 5 The example implementation of the process flow in is similar, so the differences will be highlighted. In this article, the grafting material 1221 may not necessarily include any soluble transfer material. Fig.12As shown in E, the second structure 1251 is formed to contact the grafted material 1221 without a gap therebetween. Fig.12 In F, the grafted material 1221 is removed, leaving a gap 1261 between the two lines (ie, 1211 and 1251). Fig.12 It is shown that even if the exposure pattern is misaligned so that it overlaps into the grafted material area 1221, the grafted material 1221 remains removable to leave the desired gap 1261 between the lines. Alternatively, the grafted material 1221 can include a soluble transfer material, but no diffusion process is performed to cause any diffusion. In other examples, the grafted material 1221 can include a soluble transfer material, but the amount of the soluble transfer material is insufficient to change the solubility, or the film formed during the DCS process can prevent the diffusion of the soluble transfer material.

[0069] Another embodiment is a selective coating process. In a selective coating process, the initial pattern (e.g., mandrel) can be a photoresist or hard mask material. On this initial pattern, the material is selectively attached to the mandrel relative to the base material. The pattern is then covered with another material that is organic-based or inorganic-based. The selectively coated material is then removed by RIE etching or development, depending on the material substrate, to produce narrow groove features.

[0070] A related process is an atomic layer deposition (ALD) process. The ALD material is conformally deposited on the substrate. A spacer opening etch removes the ALD material from all surfaces except vertical surfaces, leaving sidewall spacers. The spacer material provides a buffer to prevent structures from different masks from being joined. After both structures are exposed and developed, the spacer material can be dug out, for example by an etching process, leaving a desired gap between certain structures.

[0071] Various embodiments herein can benefit from various optimization techniques. For example, materials with components (e.g., TGA and crosslinker) having different and non-overlapping decomposition temperatures can be selected. Solvent compatibility should be checked to apply the outer coating without stripping the initial pattern (e.g., the first photoresist and the second photoresist). The initial pattern of the photoresist can be "frozen" or made insoluble using crosslinking to prevent the mandrel from dissolving in a subsequent developer (e.g., DCS).

[0072] Various embodiments described herein provide several advantages. For example, narrow trench or slot contacts can be formed between two structures by diffusion of a soluble transfer material despite misalignment of the photomask. The diffusion process can reduce overlay errors due to the resolution limit of the Rayleigh criterion and thus form sub-resolution "fast snap-in" and "fast snap-off" structures.

[0073] In the foregoing description, specific details have been set forth, such as the specific geometry of the processing system and the description of the various components and processes used therein. However, it should be understood that the technology herein can be practiced in other embodiments that are separated from these specific details, and such details are for the purpose of illustration rather than limitation. The embodiments disclosed herein have been described with reference to the accompanying drawings. Similarly, for the purpose of illustration, specific numbers, materials and configurations have been set forth to provide a thorough understanding. However, embodiments may be practiced without such specific details. Components having substantially the same functional configuration are represented by the same reference numerals, and therefore any redundant description may be omitted.

[0074] Various techniques have been described as multiple discrete operations to help understand various embodiments. The order of description should not be interpreted as implying that these operations are necessarily order-dependent. In fact, these operations do not need to be performed in the order presented. The described operations can be performed in an order different from the described embodiments. In additional embodiments, various additional operations can be performed and / or the described operations can be omitted.

[0075] As used herein, "substrate" or "target substrate" generally refers to an object to be processed according to the present invention. A substrate may include any material portion or structure of a device, particularly a semiconductor or other electronic device, and may be, for example, a base substrate structure, such as a semiconductor wafer, an intermediate mask, or a layer (e.g., a film) located on or superimposed on a base substrate structure. Thus, the substrate is not limited to any particular base structure, underlying or overlying layer, patterned or unpatterned, but is contemplated to include any such layer or base structure, as well as any combination of layers and / or base structures. The description may refer to a particular type of substrate, but this is for illustrative purposes only.

[0076] Those skilled in the art will also appreciate that many variations may be made to the operation of the above-described techniques while still achieving the same purpose of the present invention. Such variations are intended to be covered by the scope of the present disclosure. Therefore, the foregoing description of the embodiments of the present invention is not intended to be restrictive. Rather, any limitations to the embodiments of the present invention are presented in the following claims.

Claims

1. A method for forming a pattern on a substrate, comprising: forming a first layer on the lower layer of the substrate, the first layer being patterned to have a first structure; depositing a grafting material on a side surface of the first structure, the grafting material comprising a solubility transfer material; diffusing the solubility transfer material a predetermined distance into an adjacent structure adjacent to the solubility transfer material, the solubility transfer material changing the solubility of the adjacent structure in a developer; as well as The developer is used to remove the soluble portion of the adjacent structure to form a second structure, wherein: The first structure includes a first opening in the first layer; The adjacent structure is part of the first layer; The first layer comprises a photoresist material; and The second structure includes second openings in the first layer, wherein a latent pattern of the second openings is formed by pattern-wise exposing the first layer to actinic radiation prior to diffusing the solubility transfer material.

2. The method according to claim 1, wherein: The soluble transfer material renders the adjacent structure insoluble in the developer; and The first opening is spaced apart from the second opening by at least the predetermined distance.

3. The method according to claim 1, wherein: The soluble transfer material renders the adjacent structure soluble in the developer; and The first opening engages with the second opening.

4. The method according to claim 1, wherein: The solubility transfer material includes a base that neutralizes the acid.

5. A method for forming a pattern on a substrate, comprising: forming a patterned first layer on the lower layer of the substrate, the patterned first layer comprising a first material, and the lower layer comprising a second material chemically different from the first material, the patterned first layer having a first structure; depositing a grafted material on the substrate, the grafted material selectively adhering to the uncovered surface of the first structure, the grafted material comprising a soluble transfer material; depositing a fill material on the substrate, the fill material being adjacent to the grafted material; diffusing the solubility transfer material a predetermined distance into an adjacent portion of the fill material, the solubility transfer material changing the solubility of the adjacent portion of the fill material in a developer; as well as The developer is used to remove the soluble portion of the filler material, so that the remaining portion of the filler material forms a second structure, wherein: The solubility transfer material renders an adjacent portion of the fill material insoluble in the developer; and The first structure is in contact with the second structure.

6. The method according to claim 5, wherein: The solubility transfer material includes a thermal acid generator; and the method further includes: The thermal acid generator is activated by heat prior to diffusing the solubility transfer material into the fill material.

7. The method according to claim 5, wherein: The soluble transfer material includes a photoacid generator; and the method further includes: In diffusing the solubility transfer material into the filling material Prior to this, the photoacid generator is activated by actinic radiation.

8. The method according to claim 7, wherein: The actinic radiation is performed using a photomask such that the soluble transfer material is activated by patterned exposure to actinic radiation.

9. The method according to claim 5, wherein: The solubility transfer material includes a base that neutralizes the acid.

10. The method according to claim 5, wherein: The filling material includes a photoresist material.

11. The method according to claim 10, further comprising: Prior to diffusing the soluble transfer material into the fill material, a latent pattern of the second structure is formed in the photoresist material via patterned exposure to actinic radiation.

12. The method according to claim 11, wherein: The latent pattern overlaps an adjacent portion of the photoresist material.

13. The method according to claim 5, wherein: The first structure comprises a mandrel or a wire.

14. The method of claim 13, further comprising hardening the mandrel or the wire prior to depositing the grafted material on the substrate.

15. A method for forming a pattern on a substrate, comprising: forming a patterned first layer on the lower layer of the substrate, the patterned first layer comprising a first material, and the lower layer comprising a second material chemically different from the first material, the patterned first layer having a first structure; depositing a grafted material on the substrate, the grafted material selectively adhering to the uncovered surface of the first structure, the grafted material comprising a soluble transfer material; depositing a fill material on the substrate, the fill material being adjacent to the grafted material; diffusing the solubility transfer material a predetermined distance into an adjacent portion of the fill material, the solubility transfer material changing the solubility of the adjacent portion of the fill material in a developer; as well as removing a soluble portion of the filler material using the developer so that the remaining portion of the filler material forms a second structure, Wherein, the solubility transfer material includes a base that neutralizes the acid.

16. The method according to claim 15, wherein: The filling material includes a photoresist material.

17. The method according to claim 16, further comprising: Prior to diffusing the soluble transfer material into the fill material, a latent pattern of the second structure is formed in the photoresist material via patterned exposure to actinic radiation.

18. The method according to claim 17, wherein: The latent pattern overlaps an adjacent portion of the photoresist material.

19. The method according to claim 15, wherein: The first structure comprises a mandrel or a wire.

20. The method of claim 19, further comprising hardening the mandrel or the wire prior to depositing the grafted material on the substrate.

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