Self-aligning multi-patterning method

Abstract

A method for patterning a substrate for microfabrication. The method comprises the step of forming a first structure on a memory layer, comprising a first row of lines that are parallel to each other and spaced apart from each other. A first anti-spacer forming process is performed to form a first trench along the sidewalls of the first structure and the sidewalls of the first filling material to define a first etching pattern to be transferred into the memory layer. A second structure is formed on the memory layer, comprising a second row of lines that are parallel to each other and spaced apart from each other. The arrangement of the second row of lines is shifted relative to the first row of lines. A second anti-spacer forming process is performed to form a second trench along the sidewalls of the second structure and the sidewalls of the second filling material to define a second etching pattern to be transferred into the memory layer.

Description

Technology Field

[0001] Cross-reference regarding related applications

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 318,619 filed March 10, 2022, and U.S. Regular Application No. 17 / 989,438 filed November 17, 2022, and accordingly, these applications are incorporated herein by reference.

[0003] The present invention generally relates to a method for patterning a substrate, and in a specific embodiment, to a system and method for self-aligned multi-patterning. Background Technology

[0004] An integrated circuit (IC) is a network of electronic components formed as a monolithic structure comprising stacks of patterned layers of various materials. The structure is manufactured by processing a semiconductor substrate through a series of patterning levels in which patterned layers are formed using photolithography at each level. Component packing density nearly doubles every two years to reduce costs. To print smaller features, shorter wavelength (λ) lithography systems have been developed. The light source has been changed from Hg vapor lamps at 436 nm, 405 nm, and 365 nm λ to deep ultraviolet (DUV) excimer lasers at 248 nm and 193 nm λ. As given by the Rayleigh criterion, the resolution-limiting minimum half-pitch (HP) is proportionally reduced as λ / (4 NA), where NA is the numerical aperture. Therefore, theoretically, for λ = 193 nm, HP ≥ 48 nm, and for NA = 1.33 (using 193 nm immersion (193i)), HP ≥ 36 nm. Nevertheless, 193 nm and 193i supported nodes from 90 nm to 10 nm, and using "multi-patterning" techniques to pattern pitches below the Rayleigh limit, thereby forming multiples of feature density on the reticle within the material layer. Nodes below 10 nm are likely to use multi-patterning in conjunction with 13.5 nm extreme ultraviolet (EUV) lithography, thus requiring further innovation in multi-patterning.

[0005] A method for patterning a substrate, the method comprises the steps of: forming a first structure on a memory layer, wherein the first structure comprises lines of a first row that are parallel to each other and spaced apart from each other; performing a first anti-spacer forming process to form a first trench along the sidewall of the first structure and the sidewall of the first filling material, wherein the first trench defines a first etching pattern; transferring the first etching pattern into the memory layer and removing the material on the memory layer; forming a second structure on the memory layer, wherein the second structure comprises lines of a second row that are parallel to each other and spaced apart from each other, and the arrangement of the lines of the second row is shifted relative to the lines of the first row; performing a second anti-spacer forming process to form a second trench formed along the sidewall of the second structure and the sidewall of the second filling material, wherein the second trench defines a second etching pattern; and includes the step of transferring a second etching pattern into the memory layer and removing the material on the memory layer.

[0006] A method for patterning a substrate, wherein the pattern comprises a row of parallel end trenches having a first pitch, and the method comprises the steps of: forming a first hard mask layer on a layer to be patterned in the substrate; forming a first stencil trench on the first hard mask layer having a pitch equal to twice the first pitch, wherein each trench of the first stencil trench has a first width; forming a first hard mask trench pattern by etching the first hard mask layer using the first stencil trench as an etching mask; forming a first block mask on the first hard mask layer, wherein the first block mask covers a portion of the first hard mask trench to form a first etching pattern on the layer to be patterned; transferring the first etching pattern to the layer to be patterned to form a first group of end trenches, and removing the first block mask and the first hard mask layer. The method includes the step of transferring a second etching pattern onto a layer to be patterned to form a final trench of a second group, wherein the final trench of the second group and the final trench of the first group collectively form a final trench pattern having a first pitch, and all final trenches have the same first width.

[0007] A method for designing a reticle set, the method comprises the step of having a final design including a line-and-space (L / S) pattern having a final pitch; The method includes the step of decomposing the final design into a first reticle design and a second reticle design, wherein the first reticle design and the second reticle design are part of a reticle design for a reticle set for quadruple patterning through an anti-spacer self-aligned lithography-etching-lithography-etching (AS-SALELE) process, the first reticle design is configured to pattern a first row of mandrels having a mandrel pitch equal to four times the final pitch, the second reticle design is configured to pattern a second row of mandrels having the same mandrel pitch, and the arrangement of the second row of mandrels is shifted relative to the first row of mandrels by a distance equal to the final pitch in a direction parallel to the row of mandrels, and the first reticle design and the second reticle design are configured to form an L / S pattern having the final pitch on a substrate. Brief explanation of the drawing

[0008] Now, for a more complete understanding of the present invention and its advantages, refer to the following description in conjunction with the accompanying drawings, and as the accompanying drawings: FIGS. 1a through 1f illustrate, according to some embodiments, an exemplary final design and an exploded view of the final design for an anti-spacer self-aligned lithography-etching-lithography-etching (AS-SALELE) quadruple patterning process; FIGS. 2a to 2f illustrate cross-sectional views of a semiconductor device at various intermediate process steps of a process flow for an in-diffusion anti-spacer formation process; FIGS. 3a to 3c illustrate cross-sectional views of a semiconductor device at various intermediate process steps of a process flow for an out-diffusion anti-spacer formation process; FIGS. 4a to 4i illustrate cross-sectional and plan views of a semiconductor device at various intermediate process steps of a process flow for patterning a substrate using AS-SALELE, according to some embodiments; FIG. 5 illustrates a flowchart summarizing an embodiment of the process flow illustrated in FIG. 4a to 4i; FIGS. 6a through 6m illustrate cross-sectional and plan views of a semiconductor device at various intermediate process steps of a process flow for patterning a substrate using AS-SALELE, according to some embodiments; and FIG. 7 illustrates a flowchart summarizing an embodiment of the process flow illustrated in FIG. 6a to 6m. Specific details for implementing the invention

[0009] The present disclosure describes an embodiment of a method for patterning a substrate by a lithography-etching-lithography-etching (LELE) multi-patterning technique, wherein an etching mask comprising an anti-spacer formed by self-alignment on a patterned mandrel is used. In the anti-spacer formation process, the peripheral region of the layer is chemically modified so that the solubility of the material within such region is significantly enhanced with respect to some solvent. The modified material having high solubility is referred to as the anti-spacer material. In an embodiment, the anti-spacer material is formed by self-alignment on the mandrel and is optionally removed in a subsequent process step. The space vacated by removing the anti-spacer material forms an etching mask and is an anti-spacer. The anti-spacer comprises a trench pattern, and each trench of the trench pattern has a width equal to the thickness of the anti-spacer material formed and removed from the side of each mandrel. A multi-patterning technique using self-aligning anti-spacers is referred to in this disclosure as anti-spacer self-aligned LELE (AS-SALELE). In contrast, in the self-aligned LELE (SALELE) multi-patterning technique, spacers are formed by self-aligning to a patterned mandrel, and the material between the spacers is removed. The gap created by removing the material between the spacers forms an etching mask containing a trench pattern. Each pair of adjacent trenches in the trench pattern is separated by one of the spacers. Thus, the line width of each line separating adjacent trenches formed by the SALELE technique is equal to the width of the spacer. In contrast, the trench width of each space separating adjacent lines formed by the AS-SALELE technique is equal to the thickness of the anti-spacer material.

[0010] One advantage of using AS-SALELE technology can be attributed to the use of a step for placing anti-spacer material at the trench locations in the final design. The final design refers to a pattern that is finally etched into the layer to be patterned within the substrate. Consider a final design comprising a line-and-space (L / S) pattern having a first pitch, wherein the first pitch is the final pitch ( P ) and each trench (i.e., each space) is P It has a first width of / 2, and the first width is the final width. In the exemplary final design of the present disclosure, the final width is P / 2. As described with reference to FIGS. 1a through 1f, the final design can be decomposed into two mandrel reticle designs. Two additional reticles are used to form a block mask. The block shape is used to terminate the trench. Each mandrel reticle design is 4 P It is a row of mandrels having a mandrel pitch of . In contrast, as is known to those skilled in the art, to pattern the same final design using SALELE, each of the two decomposed reticle designs is 2 P It has feature sections arranged at a pitch. That is, AS-SALELE provides a feature density four times greater than the two feature density provided by SALELE with the same total number of masks and pitch-walking effect. A larger lithography pitch means that pitch walking can be reduced due to less process variation in the lithography process step. A larger mandrel pitch (4) at resolution for AS-SALELE P ) causes wider mandrel lines, thus providing higher patterning accuracy and reduced patterning defects, for example, reduced stochastic defects during patterning via extreme ultraviolet (EUV) lithography.

[0011] In the present disclosure, with reference to FIGS. 1a through 1f, an exemplary final design and a decomposition of the final design for an AS-SALELE quadruple patterning process are described. Then, two exemplary anti-spacer formation processes are described. In one embodiment, a chemically active species diffuses from an adjacent material into a mandrel and chemically reacts with the mandrel material within a controlled diffusion distance to convert the material therein into an anti-spacer material. This is an internal-diffusion process described with reference to FIGS. 2a through 2f. In another embodiment, a chemically active species diffuses from a mandrel into an adjacent material and chemically reacts with the adjacent material within a controlled diffusion distance to convert the material therein into an anti-spacer material. This is an external-diffusion process described with reference to FIGS. 3a through 3c. As described in more detail below, the internal-diffusion or external-diffusion anti-spacer formation processes may be used in the process flow for AS-SALELE quadruple patterning.

[0012] An exemplary embodiment of a process flow (flow A) for quadruple patterning via AS-SALELE is described with reference to the cross-sectional and plan views of a semiconductor device (400) illustrated in FIGS. 4a through 4i and summarized in the flowchart illustrated in FIG. 5. Another exemplary embodiment of a process flow (flow B) for quadruple patterning via AS-SALELE is described with reference to FIGS. 6a through 6m and summarized in the flowchart illustrated in FIG. 7. Flow A as well as flow B utilizes the reticle decomposition illustrated in FIGS. 1a through 1f and, for the sake of limitation, uses an internal-diffusion anti-spacer formation process to form a final pattern within the layer to be patterned of the substrate.

[0013] FIG. 1a illustrates a final design (100) for a pattern of a final trench (102) having sides separated by lines (104) and ends separated by blocks (106). The final trench (102) has a final pitch (P ) arranged, and each final trench of the pattern of the final trench (102) is half-pitch ( P It has the same width as / 2). In various embodiments, P The width may be approximately 10 nm to approximately 30 nm. Each final trench (102) has the same width. This is a limitation of the AS-SALELE technology because the final trench (102) is not a drawn feature: each final trench of the pattern of the final trench (102) has a width limited by the width of the anti-spacer, which is limited by the process parameter of the anti-spacer formation process. Typically, this limitation may be accepted when the technology platform supports this option for power distribution over long distances, for example, when the trench is subsequently filled with metal to form metal-level wiring used to transmit signals over short distances and also to locally supply tapped power from buried power rails.

[0014] In the exemplary final design (100), the final trench pattern is a row of columnar final trenches (102), and adjacent columns along the row are marked 1 and 1'. The markings are intended to help understand the arrangement and dimensions of the features when the final pattern (100) is broken down into a set of reticles.

[0015] The design for the first mandrel reticle (R1) and the design for the first block mask (BLK1) are described with reference to FIGS. 1b and FIGS. 1c, respectively. The features shown in FIGS. 1b and FIGS. 1c are shown superimposed on the background of the final design (100) shown in light shade in FIGS. 1b and FIGS. 1c. The design for the first mandrel reticle (R1) and the design for the first block mask (BLK1) are intended to form a first trench pattern that defines a first etching pattern for etching the final trench (102) located along the column marked 1 in the final design (100). Accordingly, during the process, an anti-spacer material is formed along the column marked 1 to form an anti-spacer line (110) placed along the side of each mandrel (120) of the first row of mandrels (120). The anti-spacer line (110), indicated by a dashed rectangle in FIG. 1b, is not a feature drawn within the first mandrel reticle (R1). The feature drawn within the first mandrel reticle (R1) is the mandrel (120) of the first row of mandrels (120). The mandrels (120) of the first row are subsequently printed within a layer formed on a substrate to be used to perform the anti-spacer formation process. During the process, the anti-spacer material is self-aligned and formed on the mandrels (120), and after the anti-spacer material is formed, the width of each mandrel (120) is 1.5, as further described below. P am.

[0016] The final design (100), which is a pattern to be etched into the layer to be patterned, does not uniquely determine the width of each mandrel (120) within the first mandrel reticle (R1). Instead, the final design (100) determines the width of each anti-spacer line (110). P Fix it to be equal to / 2 (width of each final trench (102)), and set the pitch of the anti-spacer line (110) along the column marked 1 to 2 PSecure it to be the same as the pitch of the final trench (102) along the column marked 1. 2 P The pitch and P The line width of / 2 is such that the distance between the anti-spacer lines (110) is 1.5 P This means that, as illustrated in FIG. 1b, the final design (100) has a width of 2.5 of a line of the combined mandrel and anti-spacer structure (130). P It is necessary to have (width of the two anti-spacer lines (110) (each of P / 2 width), and 1.5 separating the two anti-spacer lines (110). P The distances are added up to 2.5 P The space between adjacent lines of the combined mandrel and anti-spacer structure (130) becomes the combined width.) The space between adjacent lines of the anti-spacer structure (110) is the space (1.5) between adjacent anti-spacer lines (110). P ) is. Therefore, the row of the combined mandrel and anti-spacer structure (130) is 4 P It has a pitch. Since each combined mandrel and anti-spacer structure (130) has one mandrel, the first mandrel reticle (R1) is 4 P It has a first row of mandrels (120) drawn with a pitch.

[0017] Pitch (4 P ) is independent of which anti-spacer forming process is used, but the width of each mandrel (120) within the first mandrel reticle (R1) depends on the anti-spacer forming process. In some anti-spacer forming processes (e.g., the internal-diffusion anti-spacer forming process described below with reference to FIGS. 2a through 2f), the width of the printed mandrel is changed by an anti-spacer forming process that converts a portion of the printed mandrel into an anti-spacer material. In this case, the width of each mandrel (120) of the first mandrel reticle (R1) is 1.5 PSince it must be drawn larger, after the anti-spacer is formed, the mandrel is 1.5 as limited by the final design (100). P It is the width. If the anti-spacer forming process maintains the mandrel width unchanged (e.g., the external-diffusion anti-spacer forming process described below with reference to FIGS. 3a through 3c), each mandrel (120) is 1.5 P It is drawn with width.

[0018] The exemplary first mandrel reticle (R1) illustrated in FIG. 1b has each anti-spacer line P It is suitable for use in an internal-diffusion anti-spacer forming process with a width of / 2. The internal-diffusion anti-spacer forming process converts a portion of each mandrel (120) into an anti-spacer material. Thus, as indicated by the anti-spacer line (110) in FIG. 1B, each printed mandrel P Expected that the surrounding area of ​​ / 2 width is converted into an anti-spacer material, the mandrel (120) is 2.5 P It is drawn with width.

[0019] Blocks (106) along columns marked 1 can be patterned using a design for a first block mask (BLK1) illustrated in FIG. 1c. The design for the first block mask (BLK1) includes a block shape portion (140) that is drawn to cover the position of blocks (106) along columns marked 1 in the final design (100). As described in more detail below, blocks (106) are formed by self-aligning in a trench (102) in the row direction, and the range of the block shape portion (140) in the row direction can be drawn to be large enough to provide a sufficient margin for the edge placement error (EPE), provided that the block shape portion (140) does not extend to fall within the edge placement error (EPE) of another final trench (102) along another column marked 1.

[0020] FIGS. 1d through 1f are used to illustrate the design for a second mandrel reticle (R2) and the design for a second block mask (BLK2), which is intended to form a second trench pattern that defines a second etching pattern used to etch a final trench (102) located along a column marked 1'. For convenience, the final design (100) is reproduced in FIG. 1d.

[0021] FIG. 1e illustrates a design for a second mandrel reticle (R2) superimposed on the background of the final design (100). Similar to the first mandrel reticle (R1), the second mandrel reticle (R2) comprises a second row of mandrels (120') subsequently printed within a layer formed on a substrate. Additionally, similar to the first mandrel reticle (R1), the second mandrel reticle (R2) comprises each anti-spacer line P It is suitable for use in an internal-diffusion anti-spacer forming process with a width of / 2. Therefore, as with the mandrel (120), it is expected that the mandrel material at the location of the anti-spacer line (110') is converted into an anti-spacer material, so that each mandrel (120') is 2.5 P It is drawn with a width. As previously mentioned, similar to the first mandrel reticle (R1), each combined mandrel and anti-spacer structure (130') is 2.5 P It is the width, and 1.5 from the adjacent shaped part. P Spacing out by such a distance, just like in the case of the mandrel (120) of the first row of the first mandrel reticle (R1), the same pitch (4 P It causes the second row of the mandrel (120') of the second mandrel reticle (R2) having ).

[0022] In FIG. 1e, the anti-spacer line (110'), indicated by a dashed rectangle, runs along the column marked 1', whereas the anti-spacer line (110) (Fig. 1b) runs along the column marked 1. The rows of the columnar end trench (102) are arranged at a pitch (P) (see FIG. 1d). The columns running along these rows alternate between the column marked 1 and the column marked 1', such that the rows of the column marked 1' run a distance along the row. P It means that it is the row of the column marked 1 that is displaced by that amount. Therefore, as shown in FIG. 1e, the mandrel (120') of the second row is simply a distance along the row direction. P It is the first row mandrel (120) shifted by that amount.

[0023] The design for the second block mask (BLK2) illustrated in FIG. 1f can be used to pattern the block (106) along the column marked 1'. Similar to the design for the first block mask (BLK1), the design for the second block mask (BLK2) includes a block shape portion (140') that is drawn to cover the position of the block (106) along the column marked 1 in the final design (100).

[0024] As mentioned above, there are two methods for forming the anti-spacer described in this disclosure. In both methods, the anti-spacer material is formed to separate the mandrel and filler lines into rows of an interlocking pattern of mandrel and filler lines, and the alternating mandrel and filler lines are 4 P It is arranged at a pitch. Regardless of the formation method, after the anti-spacer material is formed, the thickness P The anti-spacer material of / 2 is a separated adjacent mandrel and filler line, and each mandrel and filler line is 4 P 1.5 matching the pitch PIt has a width. A pattern including a mandrel, filler lines, and anti-spacer material can be formed with a material deposited by an inexpensive spin-on process, typically, for example, using a spin-coating machine on a lithography track.

[0025] Two methods for forming anti-spacers are described with reference to FIGS. 2a through 2f and FIGS. 3a through 3c, respectively. As illustrated in FIGS. 2a through 2f and FIGS. 3a through 3c, the (described) interlocking pattern is formed on a layer (240) of a substrate comprising a base layer (250) below the layer (240). In an exemplary embodiment described in the present disclosure, the layer (240) may be a hard mask layer, and the base layer (250) may be a layer to be patterned.

[0026] First, the internal-diffusion anti-spacer formation process is described with reference to FIGS. 2a to 2f.

[0027] Referring to FIG. 2a, for example, using the first mandrel reticle (R1) described above with reference to FIG. 1a and FIG. 1b, the pitch (4 P A row of mandrels (220) having ) is patterned on a layer (240). The mandrel material can be selected from various materials, such as, for example, fluid materials, photoresists, and inorganic materials. In some embodiments, the mandrel material includes a photoresist, for example, a high-speed EUV photoresist. The photoresist can be patterned by exposing it to a radiation pattern defined by a reticle design (for example, a first row of mandrels (120) drawn within a first mandrel reticle (R1)). The radiation pattern is transferred to the exposed photoresist through a suitable developer to form patterned mandrels (220). The pattern transfer results in each patterned mandrel (220) having the same width as each drawn mandrel (120) of the first mandrel reticle (R1). Thus, the patterned width is 2.5 P am.

[0028] As described above, the width of each patterned mandrel (220) formed on the layer (240) depends on the anti-spacer forming process. In the exemplary embodiment described with reference to FIGS. 2a through 2f, the anti-spacer forming process includes the internal diffusion of a chemically active species that converts a portion of each mandrel (220) within a region near its periphery into an anti-spacer material. By converting the mandrel material into an anti-spacer material, the width of the patterned mandrel (220) P It is reduced by that amount, and the height P It is reduced by / 2. Therefore, before transformation, in FIG. 2a, the width of each patterned mandrel (220) is the same as the width (2.5) of the combined mandrel and anti-spacer structure (130) as described above with reference to FIG. 1b. P It is the same as ).

[0029] In FIG. 2b, the pattern of the mandrel (220) is covered with a first overcoat (260). The first overcoat (260) contains a chemically active species. For example, the first overcoat (260) may be a photoresist containing an acid or a photon that is a chemically active species. The first overcoat (260) may be formed using a spin-on process. In various embodiments, the internal diffusion of the chemically active species and the reaction with the mandrel (220) are thermally activated by annealing the substrate at a controlled temperature of about 110°C to about 220°C for about 0.5 to about 3 minutes using, for example, a heat treatment oven of a lithography track. As illustrated in FIG. 2c, the annealing temperature and annealing duration are selected to diffuse a chemically active species into the mandrel (220) and react with the mandrel material within a specific diffusion distance, thereby converting the mandrel material therein into an anti-spacer material (210). The inward arrow in FIG. 2c indicates the thickness formed by the reaction with the mandrel material in the surrounding area along the side and top of the mandrel (220). PRepresents a continuous region of the anti-spacer material (210) of / 2. 2.5 P A printed mandrel (220) (Figs. 2a and 2b) of width 1.5 P Reduced to P By forming an anti-spacer material (210) with a thickness of / 2, in FIG. 2c, the combined mandrel and anti-spacer structure (230) (a combination of the mandrel (220) and the anti-spacer material (210)) is 2.5 P It is a width.

[0030] After annealing is completed, the first overcoat (260) containing chemically active species can be optionally removed using a solvent in which the overcoat was cast, as shown in FIG. 2d.

[0031] In FIG. 2e, a first filler material (270) is deposited on a substrate. As illustrated in FIG. 2e, the first filler material (270) is a fluid material intended to flow into a space defined by the pattern of the mandrel (220). In some embodiments, the first filler material (270) is a photoresist and can be deposited by an inexpensive spin-on process. Typically, the first filler material (270) overfills the space defined by the pattern of the mandrel (220) to cover the surface of the anti-spacer material (210) with a topcoat of excess first filler material (270). Thus, a controlled recess etching step can be performed to remove the topcoat and expose the anti-spacer material (210) formed on the mandrel (220). The controlled recess etching step may use a solvent having a low dissolution rate for the exposed material. In some embodiments, the solvent may be 0.26N tetramethylammonium hydroxide (TMAH) developer. By exposing the upper surface of the anti-spacer material (210), a row of alternating mandrels (220) and filler lines (280) is formed, with the filler lines (280) separated by the anti-spacer material (210).

[0032] As mentioned above, two exemplary methods for forming anti-spacers are described in this disclosure. An internal-diffusion anti-spacer formation process is described above with reference to FIGS. 2a through 2f. An external-diffusion anti-spacer formation process is described below with reference to FIGS. 3a through 3c. In the external-diffusion process, a mandrel supplies a chemically active species that diffuses into an adjacent material and chemically reacts to convert the adjacent material within a controlled diffusion distance into an anti-spacer material. None of the mandrel materials are chemically converted into an anti-spacer material.

[0033] FIG. 3a illustrates a cross-sectional view of a semiconductor device, wherein in this embodiment, each mandrel (120) is 2.5 P Instead, 1.5 P Similar to the row of the mandrel (220) in FIG. 2a, except that it is drawn to have the same width as 4 P A row of mandrels (320) having a pitch is patterned on a layer (240) using a first mandrel reticle (R1). As described above, since a portion of the mandrel material is converted into an anti-spacer material (110) by reaction with a chemically active species, the mandrels (220) are more widely (2.5) in the internal diffusion process. P It had to be patterned (with a width of ). In the external diffusion process, the mandrel width of the row of mandrels (320) is 1.5 P It remains unchanged. Similar to the internal diffusion process, in the external diffusion process, the rows of the mandrel (320) can be patterned using a suitable lithography technique (e.g., EUV lithography).

[0034] In the external diffusion process, the mandrels of the row of mandrels (320) supply chemically active species. Thus, the mandrel material of FIG. 3a may be a photoresist containing an acid or a photon, which is a chemically active species.

[0035] In FIG. 3b, a second filler material (370) is deposited on the mandrels (320) of the patterned row. The second filler material (370) is a fluid material intended to flow into the empty space defined by the pattern of the row of the mandrels (320). When reacted with a chemically active species present within the mandrels (320) of the patterned row, the second filler material (370) is converted into an anti-spacer material. In some embodiments, the second filler material (370) is a photoresist and may be deposited by a spin-on process. In an exemplary embodiment of FIG. 3b, similar to the first filler material (270), the second filler material (370) overfills the space between the mandrels (320), and the excess material forms a topcoat.

[0036] In FIG. 3c, the substrate is annealed to diffuse chemically active species from the row of mandrels (320) into the second filler material (370). The annealing process may be similar to the annealing of the internal diffusion process described with reference to FIG. 2b and 2c. During annealing, the externally diffusing chemically active species react with a portion of the second filler material (370) adjacent to each mandrel of the row of mandrels (320). The reaction converts the region within the diffusion distance into the second filler material (370) into an anti-spacer material (310). As previously mentioned, the temperature and duration of the annealing are such that the diffusion distance PIt is selected and controlled to be identical to / 2. In some embodiments, the topcoat of the second filler material (370) as seen in FIG. 3b is completely converted into an anti-spacer material (310) to expose the anti-spacer material (310) formed on the mandrel (320), thereby forming a filler line (380) separated by the anti-spacer material (310) in a row of alternating mandrels (320) and filler lines (380). In some other embodiments, there may be a residual topcoat, and the residual topcoat may be removed by an extended development step in which the solvent used to remove the residual topcoat slowly and controllably infuses the residual topcoat due to its minimum dissolution rate, thereby exposing the anti-spacer material. By removing the top coat, as shown in FIG. 3c, the anti-spacer material (310) formed on the mandrel (320) is exposed, and the filler lines (380) separated by the anti-spacer material (310) are formed in rows of alternating mandrels (320) and filler lines (380).

[0037] Note that in the internal diffusion process, the first filler material (270) used to form the filler line (280) is deposited after the anti-spacer material (210) is formed. In contrast, in the external diffusion process, the first filler material (370) used to form the filler line (380) in rows of alternating mandrels (320) and filler lines (380) separated by the anti-spacer material (310) is deposited before the anti-spacer material (310) is formed.

[0038] Initially, the material reacting with the chemically active species has low solubility in the solvent prior to the chemical reaction. The chemical used in the anti-spacer formation process causes the material to be transformed into an anti-spacer material (a material having high solubility in the solvent) upon reaction with the chemically active species. Thus, after the chemically active species diffuses and reacts to convert the material within the diffusion distance into an anti-spacer material, the anti-spacer material can be selectively removed by the solvent. In some embodiments, where the chemically active species is an acid or a photon that diffuses into the photoresist and reacts with the photoresist, the solvent capable of selectively removing the anti-spacer material includes tetramethylammonium hydroxide (TMAH).

[0039] A row of interlocking patterns of mandrels (220) and filler lines (280) separated by an anti-spacer material (210) (shown in FIG. 2f), and a row of interlocking patterns of mandrels (320) and filler lines (380) separated by an anti-spacer material (310) (shown in FIG. 3c) have the same lateral dimensions. Thus, either anti-spacer forming process can be used to form the interlocking patterns required for the process flow for quadruple patterning through AS-SALELE.

[0040] Flow A is described with reference to the cross-sectional and plan views of the semiconductor device (400) shown in FIGS. 4a to 4i and the flowchart of FIG. 5.

[0041] As mentioned above, an exemplary embodiment of a process flow (flow A and flow B) for realizing the final design (100) (shown in FIG. 1a) through AS-SALELE quadruple patterning uses, for the sake of limitation, a set of reticles designed to match an internal-diffusion anti-spacer formation process (shown in FIG. 2a to 2f). Accordingly, the set of reticles selected for flow A and flow B has the following four reticles: a first mandrel reticle (R1); a reticle according to the design for the first block mask (BLK1); a second mandrel reticle (R2); and a reticle according to the design for the second block mask (BLK2) (shown in FIG. 1a to 1f). Accordingly, during flow A (and flow B), the initial state of the substrate is a patterned structure shown in the cross-sectional view in FIG. 2f, formed using the first mandrel reticle (R1), referred to as the first interlocking pattern. In flow A, layer (240) (Fig. 2f) is a hard mask layer, and base layer (250) (Fig. 2f) is the layer to be patterned. For clarity, the labels of layer (240) and base layer (250) in FIG. 2f are changed to hard mask layer (440) and layer to be patterned (450), respectively, in FIG. 4a through 4i.

[0042] FIG. 4a illustrates a cross-sectional and top view of a semiconductor device (400) after the anti-spacer material (210) formed by an internal-diffusion anti-spacer formation process (e.g., a first anti-spacer formation process) is selectively removed from a first interlocked pattern using a first anti-spacer material removal process. As mentioned above, the anti-spacer material (210) can be selectively removed by a solvent such as TMAH.

[0043] Referring to FIG. 4a, a first structure comprising a first row of lines that are parallel to each other and spaced apart from each other is formed on a memory layer. The first structure of FIG. 4a (e.g., mandrel (220)) and filler lines (280) (e.g., first filler material) are formed on a memory layer (e.g., hard mask layer (440)). The first structure may be formed from photoresist. In some embodiments, the hard mask layer (440) may comprise silicon nitride, and the layer to be patterned (450) may comprise silicon oxide. In some other embodiments, the hard mask layer (440) may comprise silicon carbide, titanium nitride, tantalum nitride, etc., or a combination thereof, and the layer to be patterned (450) may comprise a low-k dielectric such as carbon-doped oxide, fluorosilicate glass, porous oxide, etc.

[0044] The selective removal of the anti-spacer material (210) creates a first trench pattern (402) (e.g., a first trench formed along the sidewall of the first structure and the sidewall of the first filling material), as illustrated in FIG. 4a. Each trench of the first trench pattern (402) P It has a width of / 2, the trench follows the column marked 1, and the pitch of the first trench pattern (402) is 2 P is. In some embodiments, a trench opening ( P / 2) may be a critical dimension that limits the packing density of a static random access memory (SRAM) cell embedded in a digital logic IC, for example. By using the thickness of the anti-spacer material to limit the width of each trench of the first trench pattern (402), the critical dimension is limited by the diffusion distance. Since the diffusion distance is controlled by an annealing temperature and annealing duration instead of lithography, a critical dimension of several nanometers may be manufactured, and a controlled trench width as narrow as 4 nm may be achieved.

[0045] In FIG. 4b, a reticle according to the design for the first block mask (BLK1) described with reference to FIG. 1c is used to pattern the first block mask (460) over the first trench pattern (402). In some embodiments, the first block mask (460) may comprise spin-on-glass or titanium nitride and may be formed by selective etching on a mandrel (220), a filler line (280), and a hard mask (440) using standard etching chemicals for patterning transfer, as is known to those skilled in the art. As illustrated in FIG. 4b, the shaped portion of the first block mask (460) covers a portion of the first trench pattern (402) illustrated in FIG. 4a, thereby forming an etching pattern comprising the first trench pattern (402) illustrated in FIG. 4b, along with the mandrel (220) and filler line (280), the first block mask (460). In the present disclosure, the trenches of the first trench pattern (402) may be referred to as first stencil trenches because they form an etching pattern (e.g., a first etching pattern) for a pattern transfer etching that is subsequently performed.

[0046] In FIG. 4c, pattern transfer etching is performed to transfer the first trench pattern (402) (shown in FIG. 4a) to the hard mask layer (440), thereby forming the first group of hard mask trenches (404). The pattern transfer etching may use, for example, anisotropic reactive ion etching (RIE) through a suitable etching chemical, for example, a fluorine chemical, to etch the hard mask (440) and stop it on the layer (450) to be patterned, as shown in FIG. 4c.

[0047] After the first group of hard mask trenches (404) is formed, the mandrel (220), the filler line (280), and the first block mask (460) are removed from the substrate. The resulting structure of the semiconductor device (400) is illustrated in FIG. 4d. As illustrated in FIG. 4d, the first group of hard mask trenches (404) expose a portion of the layer to be patterned along the column marked 1. In this embodiment (flow A), the pattern of the first group of hard mask trenches (404) is not transferred to the layer (450) to be patterned at this time. Before that, a second group of hard mask trenches is formed to expose another portion of the layer (450) to be patterned, which is along the column marked 1'. In flow A, the layer (450) to be patterned can be etched after exposing a portion along the column marked 1'.

[0048] The method for forming the second group of hard mask trenches is similar to the method for forming the first group of hard mask trenches (404). After forming the first group of hard mask trenches (404), an internal-diffusion anti-spacer forming process flow (as described above with reference to FIGS. 2a through 2f) may be executed to form a second interlocking pattern on the hard mask (440) using a second mandrel reticle (R2). Note that the internal-diffusion anti-spacer forming process is selected for limitation purposes only. This may be replaced by an external-diffusion anti-spacer forming process (as described above with reference to FIGS. 3a through 3c) using a suitable material and reticle to form the same second interlocking pattern.

[0049] The second interlocking pattern (formed using the second mandrel reticle (R2)) is identical to the first interlocking pattern (formed using the first mandrel reticle (R1)) except that the anti-spacer line of the second interlocking pattern follows the column marked 1' instead of the column marked 1. That is, the first interlocking pattern along the row distance ( P By shifting by ) a second interlocking pattern is created. Additionally, the second mandrel reticle (R2) is designed to be used with the same internal-diffusion anti-spacer forming process as the first mandrel reticle (R1) to form a second interlocking pattern, namely, the width of the mandrel (120) of the first mandrel reticle (R1) (Fig. 1b), and the width of the mandrel (120') of the second mandrel reticle (R2) (Fig. 1e) are 2.5 P And likewise, the pitch of the first row of mandrels (of the first mandrel reticle (R1)), and the pitch of the second row of mandrels (of the second mandrel reticle (R2)) are 4 P am.

[0050] The material and process for forming the second interlocking pattern may be similar to the aforementioned for forming the first interlocking pattern.

[0051] After forming a second interlocking pattern, the anti-spacer material formed by an internal-diffusion anti-spacer forming process (e.g., a second anti-spacer forming process) is removed from the second interlocking pattern (i.e., a second anti-spacer material removal process). FIG. 4e illustrates the structure of a semiconductor device (400) after the anti-spacer material has been selectively removed by a solvent such as TMAH.

[0052] Referring to FIG. 4e, a second structure comprising lines of a second row that are parallel to each other and spaced apart from each other is formed on the memory layer. By removing the anti-spacer material, rows of alternating mandrels (220') (e.g., the second structure) and filler lines (280') (e.g., the second filler material) separated by trenches (406) of the second pattern are formed on the hard mask layer (440) (e.g., the memory layer). The trenches (406) of the second pattern in FIG. 4e (e.g., second trenches formed along the sidewalls of the first structure and the sidewalls of the first filler material) may be identical to the first trench pattern (402) ( FIG. 4a), but with a distance ( P It can be shifted compared to the first trench pattern (402) by ) amount. P Due to the shift following the row by that amount, the hard mask trench (404) of the first group in FIG. 4c and FIG. 4d is now 1.5 as shown in FIG. 4e. P It is covered by a wide mandrel (220') and a filler line (280').

[0053] In FIG. 4f, the design for the second block mask (BLK2) described with reference to FIG. 1f is used to pattern the second block mask (460') over the trench (406) of the second pattern. As shown in FIG. 4f, the shape portion of the first block mask (460') forms an etching pattern including the trench (406) of the second pattern as shown in FIG. 4f by covering a portion of the trench (406) of the second pattern as shown in FIG. 4e, and the definition of the trench (406) of the second pattern includes the second block mask (460') along with the mandrel (220') and the filler line (280'). In the present disclosure, the trenches of the second pattern trench (406) may be referred to as second stencil trenches because they form an etching pattern (e.g., a second etching pattern) for a pattern transfer etching that is subsequently performed.

[0054] The materials and processes used to form the second block mask (460') may be similar to those used to form the first block mask (460).

[0055] In FIG. 4g, pattern transfer etching is performed to transfer the second pattern trench (406) (shown in FIG. 4e) to the hard mask layer (440), thereby forming a second group of hard mask trenches (408). The etching process may be similar to that used to form the first group of hard mask trenches (404).

[0056] In FIG. 4h, the material on the hard mask layer (440), including the mandrel (220'), filler line (280'), and second block mask (460'), was removed after forming the second group of hard mask trenches (408). The second group of hard mask trenches (408) and the first group of hard mask trenches (404) are, as shown in FIG. 4h, the final pitch ( P A hard mask trench pattern (410) having ) is collectively formed. The hard mask trench pattern (410) matches the final design (100) as can be seen from the comparison of the final design (100) of FIG. 4i and the plan view of the semiconductor device (400). Thus, the hard mask trench pattern (410) is used as an etching mask to pattern a layer (450) to be patterned into a pattern that replicates the final design (100).

[0057] FIG. 4i illustrates a semiconductor device (400) after the layer (450) to be patterned is etched and the hard mask (440) is removed, using a hard mask trench pattern (410) (shown in FIG. 4h) as an etching mask. The etching transfers the hard mask trench pattern (410) to the layer (450) to be patterned to form a final trench pattern (420). The final trench pattern (420) is a final pitch ( P Each trench of the final trench pattern (420) includes a row of columnar trenches having ), and each trench of the final trench pattern (420) PIt has a width of / 2. As can be seen from the comparison of the final design (100) and the plan view of the semiconductor device (400) in FIG. 4i, the final design (100) is replicated by the final trench pattern (420) within the layer (450) to be patterned. Two cross-sectional views are shown in FIG. 4i. One cross-sectional view labeled A is in a plane without the shape portion of the block mask (460') during the process, whereas the second cross-sectional view labeled B shows two block trenches within the final trench pattern (420).

[0058] A summary of process flow A for quadruple patterning through the aforementioned AS-SALELE with reference to FIGS. 4a to 4i is summarized in the flowchart shown in FIG. 5.

[0059] As shown in box (510), a final design for patterning into the layer to be patterned is provided. The final design is half of the final pitch ( P / 2) width and final pitch ( P Includes the final trench, which is arranged in an L / S pattern.

[0060] In box (520), the final design is broken down into first and second reticle designs, and each design is 2 P Includes the row of the pitch mandrel, and follows the row P Except for the shift, the rows are identical.

[0061] Flow A provides a first mandrel reticle according to a first reticle design and a second mandrel reticle according to a second reticle design, together with a substrate having a layer to be patterned and a hard mask layer formed on the layer to be patterned, as illustrated in box (530).

[0062] In boxes (540 and 542), a first trench pattern is formed using a first mandrel reticle and a first block mask. In flow A, before transferring the first trench pattern to a hard mask layer, a first block mask is formed and included within the first trench pattern.

[0063] As explained in more detail below, it is noted that before forming the first block mask, the first trench pattern is transferred to the hard mask layer, thereby causing flow B to deviate from flow A.

[0064] In box (550), a first trench pattern is transferred to a hard mask layer to form a first group of hard mask trenches. As previously described, the first trench pattern is a space formed by selectively etching the anti-spacer material from a row of alternating mandrels and filler lines separated by the anti-spacer material. As shown in box (550), after forming the first group of hard mask trenches, the material on the hard mask layer is removed.

[0065] The process of the boxes (540, 542, and 550) used to form the first group of hard mask trenches is repeated in the process of the boxes (560, 562, and 570), except that, this time, the second mandrel reticle and the second block mask are used to form the second group of hard mask trenches. Thus, the second group of hard mask trenches are formed along the row direction relative to the column in which the first group of hard mask trenches were formed. P It is formed as a column shifted by that amount.

[0066] Note that in flow A, the hard mask trenches of the first and second groups are formed within the same hard mask layer. In contrast, as described in more detail below, flow B forms a first hard mask trench pattern within the first hard mask layer and a second hard mask trench pattern within the second hard mask layer.

[0067] As shown in box (580), the first group of hard mask trenches and the second group of hard mask trenches collectively form a hard mask trench pattern that is transferred to the layer to be patterned. As specified in box (580), the pattern transfer etching forms a final trench pattern that replicates the final design, and the trenches P Width and pitch of / 2 P has

[0068] Another exemplary embodiment of a process flow (flow B) for quadruple patterning via AS-SALELE is described with reference to FIGS. 6a through 6m and summarized in the flowchart illustrated in FIG. 7. Those skilled in the art understand that, using the aspects of the invention of the embodiment of quadruple patterning via AS-SALELE described in this disclosure, other process flows can be constructed in addition to flows A and B.

[0069] Flow B replicates the final design (100) (shown in FIG. 1a) within the patterned layer (450) of the semiconductor device (400) using the same set of reticles used in Flow A (i.e., the first mandrel reticle (R1), the reticle according to the design for the first block mask (BLK1), the second mandrel reticle (R2), and the reticle according to the design for the second block mask (BLK2) (described above with reference to FIG. 1a through 1f)) to replicate the final design (100) within the patterned layer (450) of the semiconductor device (400). As mentioned above, the first mandrel reticle (R1) and the second mandrel reticle (R2) are designed to correspond to an internal-diffusion anti-spacer formation process (shown in FIG. 2a through 2f). The internal-diffusion anti-spacer formation process is selected only for limitation. Accordingly, using the reticle design for the first mandrel reticle (R1) and the first block mask (BLK1), a first interlocked pattern (shown in FIG. 2f) was formed in flow B.

[0070] As in flow A, after forming the first interlocked pattern, the anti-spacer material (210) is optionally removed to form the same structure for the semiconductor device (400) as shown in FIG. 6a (reproduced in FIG. 4a). The structure shown in FIG. 4a is identical to the structure shown in FIG. 6a, and the same reference numbers are used for the rows of mandrels (220), the filler lines (280), and the layer to be patterned (450). However, the hard mask layer (440) of FIG. 4a is changed to the first hard mask layer (640) of FIG. 6a. Unlike flow A, in flow B, the change from 440 to 640 is made because the first hard mask layer (640) is removed in a subsequent step and a second hard mask layer is formed on the layer to be patterned (450). Additionally, the first trench pattern (402) of FIG. 4a is referred to as the first trench pattern (602) in FIG. 6a. In flow A, the first block mask (460) is included when defining the etching pattern of the first trench pattern (402) that is subsequently transferred to the hard mask layer (440), whereas in flow B, the first trench pattern (602) that is transferred to the first hard mask layer (640) to form the pattern of the first hard mask trench (604) does not include the first block mask (460), so a change from 402 to 602 is made.

[0071] In FIG. 6b, pattern transfer etching is performed before transferring the first pattern of the trench (602) without deformation to the first hard mask layer (640). The etching process removes the exposed portion of the first hard mask layer (640) to form the first hard mask trench pattern (604). The structure of the semiconductor device (400) after the pattern transfer etching is completed is shown in FIG. 6b, indicating that the first hard mask trench pattern (604) has a trench that exposes a portion of the layer (450) to be patterned along the column marked 1 without any blocks.

[0072] In FIG. 6c, the row of mandrel (220) and the filler line (280) (shown in FIG. 6b) are removed, and a first block mask (460) is formed using a reticle according to the design for the first block mask (BLK1). The first block mask (460) covers a portion of the first hard mask trench (604). The pattern of the first hard mask trench (604) having the portion covered by the first block mask (460) forms a first etching pattern on the layer (450) to be patterned, as shown in FIG. 6c.

[0073] FIG. 6d illustrates the structure of a semiconductor device (400) after a first etching pattern is transferred to a layer (450) to be patterned to form a final trench (606) of a first group. Each pattern transfer etching is a selective etching that is blocked within an area covered by a first block mask (460) or a first hard mask layer (640) while removing an exposed portion of the layer (450) to be patterned.

[0074] After forming the final trench (606) of the first group, the first block mask (460) and the first hard mask layer (640) are successively removed from the substrate as shown in FIGS. 6e and FIGS. 6f. FIGS. 6e shows the structure of the semiconductor device (400) after removing the first block mask (460), and FIGS. 6f shows the structure of the semiconductor device (400) after removing the first hard mask layer (640).

[0075] As described above and illustrated in FIGS. 6b through 6e, the patterned first hard mask layer (640) covers the layer (450) to be patterned within the region between adjacent columns marked 1. Thus, this covered region is protected from being removed by pattern transfer etching performed through the first etching pattern (as described above with reference to FIGS. 6c through 6d). When formed, the pattern of the first hard mask trench (604) exposes the layer (450) to be patterned without being blocked along the entire length of each column marked 1 (see FIG. 6b). However, the first block mask (460), when formed over the pattern of the first hard mask trench (604), fills a portion of the pattern of the first hard mask trench (604) (see FIG. 6c). Depending on the filling, a portion of the patterned layer (450) placed adjacently below is protected from being removed (see FIG. 6d). Thus, as can be seen in the top view of FIG. 6e, the trench of the final trench (606) of the first group extending along the column marked 1 is blocked by the unremoved portion of the patterned layer (450) protected from the etchant by the first block mask (460) filling each portion of the trench of the pattern of the first hard mask trench (604). Since the first block mask (460) is removed in FIG. 6e, a portion of the pattern of the first hard mask trench (604) that is currently not filled is visible in the cross-sectional view of the semiconductor device (400) of FIG. 6e.

[0076] In FIG. 6f, the first hard mask layer (640) is removed after the first block mask (460) is removed. The top view of the semiconductor device (400) in FIG. 6f indicates that a portion of the final design (100) is replicated along the column marked 1 within the layer (450) to be patterned with the pattern of the first group of final trenches (606). As shown in FIG. 6f, each trench of the first group of final trenches (606) PA pattern having a final width of / 2 and including the final trench (606) of the first group is 2 P It has a pitch. Since the area between adjacent columns marked 1 includes the column marked 1', a portion of the final design (100) following the column marked 1' will still be replicated within the layer (450) to be patterned.

[0077] FIG. 6g illustrates a second hard mask layer (650) formed on a layer (450) to be patterned. The second hard mask layer (650), which fills the final trench (606) of the first group along the column marked 1, may be formed using a process and material similar to that used to form the hard mask layer (440) described with reference to FIG. 4a (similar to the first hard mask layer (640)).

[0078] After forming the second hard mask layer (650), by repeating the steps described above with reference to FIGS. 6a through 6f, a second group of final trenches (612) may be formed along the column marked 1', but the first mandrel reticle (R1) is replaced with the second mandrel reticle (R2), and the reticle according to the design for the first block mask (BLK1) is replaced with the reticle according to the design for the second block mask (BLK2). By using these reticles, the pattern of the second group of final trenches (612) replicates a portion of the final design (100) along the column marked 1' within the layer (450) to be patterned. FIGS. 6h through 6m illustrate plan and cross-sectional views of the semiconductor device (400) at various intermediate stages forming the second group of final trenches (612). The structure of the semiconductor device (400) after the process for forming the final trench (612) of the second group is completed and the second hard mask layer (650) is removed is shown in FIG. 6m.

[0079] FIG. 6h illustrates a trench (608) of a second pattern (similar to the first trench pattern (602) of FIG. 6a) formed by removing anti-spacer material from a second interlocking pattern formed on a second hard mask layer (650) using a second mandrel reticle (R2). As previously mentioned, the second interlocking pattern is formed by a distance in a direction perpendicular to the mandrel of the row of mandrels (220'). P It is a first interlocking pattern shifted by that amount. Accordingly, the trench of the second pattern (608) is positioned along the column marked 1'.

[0080] In FIG. 6i (similar to FIG. 6b), the pattern of the second hard mask trench (610) is etched into the second hard mask layer (650) along the column marked 1' through the trench (608) of the second pattern.

[0081] In FIG. 6j (similar to FIG. 6c), the rows of mandrel (220') and filler lines (280') (see FIG. 6i) are removed, and a second block mask (460') is formed using a reticle according to the design for the second block mask (BLK2). Since the second block mask (460') covers a portion of the second hard mask trench (610), a second etching pattern is formed on the layer (450) to be patterned.

[0082] In FIG. 6k, by performing pattern transfer etching through a second etching pattern, the final trench (612) of the second group is formed within the layer (450) to be patterned.

[0083] After forming the final trench (612) of the second group, the second block mask (460') and the second hard mask layer (650) are successively removed from the substrate, respectively, as shown in FIGS. 61 and 6m, similar to the process performed after forming the final trench (606) of the first group (see FIGS. 6e and 6f). Note that the final trench (606) of the first group and the final trench (612) of the second group formed using flow B collectively form the same pattern as the final trench pattern (420) (shown in FIG. 4i) formed using flow A. Thus, the final design (100) can be replicated within the layer (450) to be patterned using flow A or flow B.

[0084] The structure of the semiconductor device (400) after removing the second hard mask layer (650) is illustrated in FIG. 6m. The final trench pattern (420) (combined final trench of the first group (606) and final trench of the second group (612)) is, P Each trench of the final trench pattern (420) includes a row of columnar trenches having a final pitch, and each trench of the final trench pattern (420) P It has a width of / 2. As expected, the two cross-sectional views of the structure of the semiconductor device (400) in FIG. 6m are identical to the two cross-sectional views of the structure of the semiconductor device (400) in FIG. 4i.

[0085] A summary of process flow B for quadruple patterning through the aforementioned AS-SALELE with reference to FIGS. 6a to 6m is summarized in the flowchart shown in FIG. 7.

[0086] As shown in box (710), a first hard mask layer is formed on the layer to be patterned of the substrate.

[0087] In box (712), a first mandrel pattern is formed on the first hard mask layer. The mandrel is 4 P It is arranged in rows with a pitch of, where P is the final pitch, and P / 2 is the final width of the final trench pattern.

[0088] In box (714), a first interlocking pattern of rows of alternating mandrels and filler lines separated by an anti-spacer material is formed from the first mandrel pattern. The anti-spacer material is formed by self-aligning to the mandrel using an anti-spacer forming process.

[0089] As shown in box (716), the anti-spacer material is selectively removed from the first interlocking pattern of rows of alternating mandrels and filler lines. The gap created by the removal forms the first trench pattern. The first trench pattern is 2 P Each trench of the first trench pattern has a pitch, and P It has the width of.

[0090] In box (718), the first trench pattern is used as an etching mask during pattern transfer etching to form the first hard mask trench pattern by etching the first hard mask layer. After forming the first hard mask trench pattern, the material on the first hard mask layer (i.e., mandrel and filler lines) is removed.

[0091] In the box (720), a first block mask is formed on the first hard mask layer. The first block mask covers a portion of the first hard mask trench to form a first etching pattern on the layer to be patterned.

[0092] In box (722), the first etching pattern is transferred to the layer to be patterned to form the final trench of the first group. After forming the final trench of the first group, the first block mask is removed. After removing the first block mask, the first hard mask layer is removed.

[0093] As shown in box (730), by repeating the process of boxes (710, 712, 714, 716, 718, and 720), a second etching pattern is formed on the layer to be patterned. However, the reticle used to form the first mandrel pattern and the reticle used to form the first block mask are modified to form the second mandrel pattern and the second block mask. The second mandrel pattern is formed by a distance in a direction perpendicular to the mandrel. P It is the first mandrel pattern shifted by that amount.

[0094] In box (732), the second etching pattern is transferred to the layer to be patterned to form the second group of final trenches. After forming the second group of final trenches, the second block mask is removed. After removing the second block mask, the second hard mask layer is removed. The second group of final trenches and the first group of final trenches collectively form a final trench pattern. The final trench pattern has a final pitch of P, and each final trench is P It has a final width of / 2.

[0095] In the present disclosure, two exemplary embodiments of quadruple patterning through AS-SALELE have been described. In both embodiments (flow A and flow B), the final design (100) is a final pitch ( P ) and final width( P A pitch (420) that is replicated within the layer (450) to be patterned by forming a final trench pattern (420) that also has / 2) P Arranged as ) P Includes a parallel trench pattern of width / 2.

[0096] An interlocking pattern comprising rows of mandrel and filler lines, respectively, separated by an anti-spacer material, can be formed on a substrate using an inexpensive spin-on process and oven available in a lithography track and using commonly available materials.

[0097] Trench width at critical dimension (CD) P / 2) is limited by the thickness of the anti-spacer material formed by self-alignment on the mandrel. Therefore, in quadruple patterning via AS-SALELE, CD control is determined by the thickness control of the anti-spacer formation process. Accordingly, it provides the advantage of stricter control than is possible for CDs limited by photolithography. In various embodiments, the thickness of the anti-spacer material can be controlled with a 3-sigma deviation of about 1 nm to about 2 nm.

[0098] Each mandrel pattern used in an exemplary embodiment of quadruple patterning via AS-SALELE is 4 P It is a row of mandrels arranged at a pitch of . The pattern is 1.5 P and 2.5 P It is printed using a reticle having line and spatial feature sizes. At a technology node of less than 10 nm, the final pitch ( P ) can be proportionally reduced to the range for forming a mandrel pattern using EUV lithography. As is known to those skilled in the art, in EUV lithography, patterning capabilities are often limited by stochastic effects. 1.5 used in an embodiment of quadruple patterning via AS-SALELE P and 2.5 P The larger size of the resist feature provides the advantage of reducing the stochastic effect of EUV lithography.

[0099] In contrast to quadruple patterning with spacers self-aligned on the mandrel, another advantage of quadruple patterning with anti-spacers self-aligned on the mandrel is that the number of rows of trenches in the final design is limited to multiples of 2 in the case of quadruple patterning with anti-spacers, whereas in the case of quadruple patterning with spacers, the number of rows of trenches is limited to multiples of 4.

[0100] Example 1. A method for patterning a substrate, the method comprising: a step of forming a first structure on a memory layer, wherein the first structure comprises lines of a first row that are parallel to each other and spaced apart from each other; a step of performing a first anti-spacer forming process to form a first trench along the sidewall of the first structure and the sidewall of a first filler material, wherein the first trench defines a first etching pattern; a step of transferring the first etching pattern into the memory layer and removing the material on the memory layer; a step of forming a second structure on the memory layer, wherein the second structure comprises lines of a second row that are parallel to each other and spaced apart from each other, and the arrangement of the lines of the second row is shifted relative to the lines of the first row; a step of performing a second anti-spacer forming process to form a second trench formed along the sidewall of the second structure and the sidewall of a second filler material, wherein the second trench defines a second etching pattern; A method for patterning a substrate, comprising the steps of transferring the second etching pattern into the memory layer and removing the material on the memory layer.

[0101] Example 2. The method of Example 1, further comprising the step of forming a first block mask on the first trench before transferring the first etching pattern into the memory layer, wherein the first block mask covers a portion of the first trench and the first etching pattern includes the first block mask.

[0102] Example 3. In either Example 1 or 2, the method further comprises the step of forming a second block mask over the second trench before transferring the second etching pattern into the memory layer, wherein the second block mask covers a portion of the second trench and the second etching pattern includes the second block mask.

[0103] Example 4. A method comprising, in any one of Examples 1 to 3, further a step of patterning a layer to be patterned disposed below the memory layer based on the first etching pattern within the memory layer and the second etching pattern within the memory layer.

[0104] Example 5. A method in any one of Examples 1 to 4, wherein the step of performing the first anti-spacer forming process comprises: covering the first structure with a first overcoat; annealing the substrate to form an anti-spacer material layer along the side of the first structure, wherein the anti-spacer material layer is formed from the first structure and the first overcoat; and after forming the anti-spacer material, selectively removing the first overcoat to form a plurality of trenches; and filling the plurality of trenches with a filler material.

[0105] Example 6. A method in any one of Examples 1 to 5, wherein the first anti-spacer forming process comprises an internal diffusion process, and the peripheral region of the first structure is converted to form the anti-spacer material layer.

[0106] Example 7. A method in any one of Examples 1 to 6, wherein the step of filling the plurality of trenches comprises: a step of overfilling the plurality of trenches with the filler material; and a step of exposing the outer surface of the anti-spacer material using a controlled recess etching step.

[0107] Example 8. A method in any one of Examples 1 to 7, wherein the step of carrying out the first anti-spacer forming process comprises: covering the first structure with a filler material; and annealing the substrate to form an anti-spacer material layer along the side of the first structure, wherein the anti-spacer material layer is formed from the first structure and the filler material.

[0108] Example 9. A method in any one of Examples 1 to 8, wherein the first anti-spacer forming process comprises an external diffusion process, and a portion of the filler material is converted to form the anti-spacer material layer.

[0109] Example 10. A method in any one of Examples 1 to 9, wherein the step of performing the first anti-spacer forming process further comprises the step of exposing the outer surface of the anti-spacer material layer using a controlled recess etching process.

[0110] Example 11. A method in any one of Examples 1 to 10, wherein the first anti-spacer material removal process comprises the step of exposing the substrate to a solvent to selectively remove the anti-spacer material formed by self-alignment on the first structure.

[0111] Example 12. A method in any one of Examples 1 to 11, wherein the solvent comprises tetramethylammonium hydroxide (TMAH).

[0112] Example 13. A method for patterning a substrate, wherein the pattern comprises a row of parallel end trenches having a first pitch, the method comprising: forming a first hard mask layer on a layer to be patterned in the substrate; forming a first stencil trench on the first hard mask layer having a pitch equal to twice the first pitch, wherein each trench of the first stencil trench has a first width; forming a first hard mask trench pattern by etching the first hard mask layer using the first stencil trench as an etching mask; and forming a first block mask on the first hard mask layer, wherein the first block mask covers a portion of the first hard mask trench to form a first etching pattern on the layer to be patterned. A method for patterning a substrate, comprising: a step of transferring a first etching pattern to a layer to be patterned to form a first group of final trenches and removing the first block mask and the first hard mask layer; and a step of transferring a second etching pattern to a layer to be patterned to form a second group of final trenches, wherein the second group of final trenches and the first group of final trenches collectively form a final trench pattern having the first pitch, and all of the final trenches have the same first width.

[0113] Example 14. Method of Example 13, wherein the first width is equal to half of the first pitch.

[0114] Example 15. In either Example 13 or 14, the step of forming the first stencil trench comprises: forming a first mandrel pattern on the first hard mask layer, wherein the first mandrel pattern is a row of mandrels having four times the first pitch; forming a first interlocking pattern of rows of alternating mandrels and filler lines separated by an anti-spacer material from the first mandrel pattern, wherein the filler lines and the anti-spacer material are formed by self-aligning to the mandrels, and each mandrel and each filler line of the first interlocking pattern has a combined width equal to three times the first width; and selectively removing the anti-spacer material from the first interlocking pattern to form the first stencil trench.

[0115] Example 16. A method in any one of Examples 13 to 15, wherein the step of selectively removing the anti-spacer material comprises the step of exposing the substrate to a solvent to remove the anti-spacer material from the first interlocked pattern in order to form the first stencil trench.

[0116] Example 17. A method in any one of Examples 13 to 16, wherein the solvent comprises tetramethylammonium hydroxide (TMAH).

[0117] Example 18. In any one of Examples 13 to 17, before transferring the second etching pattern to the layer to be patterned, the method comprises: forming a second hard mask layer on the final trench of the first group and on the layer to be patterned within the substrate; forming a second stencil trench on the first hard mask layer having a pitch equal to twice the first pitch, wherein each trench of the second stencil trench has the first width, the second stencil trench is formed by self-aligning to the mandrel of the second mandrel pattern, and the second mandrel pattern is formed shifted relative to the first mandrel pattern by a distance equal to the first pitch; and forming a second hard mask trench pattern by etching the second hard mask layer using the second stencil trench as an etching mask. A method comprising the step of forming a second block mask on the second hard mask layer, wherein the second block mask covers a portion of the second hard mask trench to form a second etching pattern on the layer to be patterned.

[0118] Example 19. A method in any one of Examples 13 to 18, wherein the step of forming the second stencil trench comprises: forming a second mandrel pattern on the second hard mask layer, wherein the second mandrel pattern is shifted relative to the first mandrel pattern by a distance equal to the first pitch; and forming a second interlocked pattern from the second mandrel pattern using an anti-spacer forming process.

[0119] Example 20. A method for designing a reticle set, the method comprising the step of having a final design including a line-and-space (L / S) pattern having a final pitch; A method for designing a reticle set, comprising the step of decomposing the final design into a first reticle design and a second reticle design, wherein the first reticle design and the second reticle design are part of a reticle design for a reticle set for quadruple patterning through an anti-spacer self-aligned lithography-etching-lithography-etching (AS-SALELE) process, wherein the first reticle design is configured to pattern a first row of mandrels having a mandrel pitch equal to four times the final pitch, the second reticle design is configured to pattern a second row of mandrels having the same mandrel pitch, and the arrangement of the second row of mandrels is shifted relative to the first row of mandrels by a distance equal to the final pitch in a direction parallel to the mandrels of the row, and wherein the first reticle design and the second reticle design are configured to form an L / S pattern having the final pitch on a substrate.

[0120] Example 21. Method in Example 20, wherein the space of the L / S pattern has a width equal to half of the final pitch.

[0121] Example 22. A method in which, in either Example 20 or 21, the final design is further broken down into a design for a first block reticle and a second block reticle, wherein the first block reticle and the second block reticle are part of the set of reticles, the first block reticle is configured to form a first block mask, and the second block reticle is configured to form a second block mask.

[0122] Example 23. A method in any one of Examples 20 to 22, wherein the first block mask comprises a plurality of first blocks configured to block a first hard mask trench configured to be formed on the side of one of the first row of mandrels, and the second block mask comprises a plurality of second blocks configured to block a second hard mask trench configured to be formed on the side of one of the second row of mandrels.

[0123] Example 24. A method in any one of Examples 20 to 23, wherein one of the first blocks is spaced apart from an adjacent one of the second blocks by a space greater than half of the final pitch.

[0124] Example 25. A method in any one of Examples 20 to 24, wherein one of the first blocks is spaced apart from an adjacent one of the first blocks by a space greater than half of the final pitch.

[0125] Although the present invention has been described with reference to exemplary embodiments, such description is not intended to be interpreted in a limiting sense. By referring to the description, various modifications and combinations of the exemplary embodiments, as well as other embodiments of the present invention, will be apparent to those skilled in the art. Accordingly, the appended claims are intended to include any such modifications or embodiments.

Claims

Claim 1 A method for patterning a substrate, the method comprises: a step of forming a first structure on a memory layer, wherein the first structure comprises lines of a first row that are parallel to each other and spaced apart from each other; a step of performing a first anti-spacer forming process to form a first anti-spacer material layer covering at least the sidewalls of the first structure; a step of forming a first filler material covering at least the sidewalls of the first anti-spacer material layer; a step of removing at least a portion of the first anti-spacer material layer to form a first trench along the sidewalls of the first structure and the sidewalls of the first filler material, wherein the first trench defines a first etching pattern; a step of transferring the first etching pattern into the memory layer and removing the material on the memory layer; A step of forming a second structure on the memory layer, wherein the second structure comprises lines of a second row that are parallel and spaced apart from each other, and the arrangement of the lines of the second row is shifted relative to the lines of the first row; a step of performing a second anti-spacer forming process to form a second anti-spacer material layer covering at least the sidewalls of the second structure; a step of forming a second filler material covering at least the sidewalls of the second anti-spacer material layer; a step of removing at least a portion of the second anti-spacer material layer to form a second trench formed along the sidewalls of the second structure and the sidewalls of the second filler material, wherein the second trench defines a second etching pattern; A method for patterning a substrate, comprising the steps of: transferring the second etching pattern into the memory layer and removing the material on the memory layer; and further comprising the step of forming a first block mask on the first trench before transferring the first etching pattern into the memory layer, wherein the first block mask covers a portion of the first trench and the first etching pattern includes the first block mask. Claim 2 delete Claim 3 The method of claim 1 further comprises the step of forming a second block mask on the second trench before transferring the second etching pattern into the memory layer, wherein the second block mask covers a portion of the second trench and the second etching pattern includes the second block mask. Claim 4 A method for patterning a substrate, the method comprises: a step of forming a first structure on a memory layer, wherein the first structure comprises lines of a first row that are parallel to each other and spaced apart from each other; a step of performing a first anti-spacer forming process to form a first anti-spacer material layer covering at least the sidewalls of the first structure; a step of forming a first filler material covering at least the sidewalls of the first anti-spacer material layer; a step of removing at least a portion of the first anti-spacer material layer to form a first trench along the sidewalls of the first structure and the sidewalls of the first filler material, wherein the first trench defines a first etching pattern; a step of transferring the first etching pattern into the memory layer and removing the material on the memory layer; A step of forming a second structure on the memory layer, wherein the second structure comprises lines of a second row that are parallel and spaced apart from each other, and the arrangement of the lines of the second row is shifted relative to the lines of the first row; a step of performing a second anti-spacer forming process to form a second anti-spacer material layer covering at least the sidewalls of the second structure; a step of forming a second filler material covering at least the sidewalls of the second anti-spacer material layer; a step of removing at least a portion of the second anti-spacer material layer to form a second trench along the sidewalls of the second structure and the sidewalls of the second filler material, wherein the second trench defines a second etching pattern; The method comprises the steps of transferring the second etching pattern into the memory layer and removing the material on the memory layer, and the step of executing the first anti-spacer forming process comprises: covering the first structure with a first overcoat; and annealing the substrate to form the first anti-spacer material layer along the side of the first structure, wherein the first anti-spacer material layer is formed from the first structure and the first overcoat.A method comprising: a step of selectively removing the first overcoat to form a plurality of trenches after forming the first anti-spacer material layer; and a step of filling the plurality of trenches with a filler material. Claim 5 A method according to claim 4, wherein the first anti-spacer forming process comprises an internal diffusion process, and the peripheral region of the first structure is converted to form the first anti-spacer material layer. Claim 6 A method according to claim 4, wherein the step of filling the plurality of trenches comprises: a step of overfilling the plurality of trenches with the filler material; and a step of exposing the outer surface of the first anti-spacer material layer using a controlled recess etching step. Claim 7 A method for patterning a substrate, the method comprises: a step of forming a first structure on a memory layer, wherein the first structure comprises lines of a first row that are parallel to each other and spaced apart from each other; a step of performing a first anti-spacer forming process to form a first anti-spacer material layer covering at least the sidewalls of the first structure; a step of forming a first filler material covering at least the sidewalls of the first anti-spacer material layer; a step of removing at least a portion of the first anti-spacer material layer to form a first trench along the sidewalls of the first structure and the sidewalls of the first filler material, wherein the first trench defines a first etching pattern; a step of transferring the first etching pattern into the memory layer and removing the material on the memory layer; A step of forming a second structure on the memory layer, wherein the second structure comprises lines of a second row that are parallel and spaced apart from each other, and the arrangement of the lines of the second row is shifted relative to the lines of the first row; a step of performing a second anti-spacer forming process to form a second anti-spacer material layer covering at least the sidewalls of the second structure; a step of forming a second filler material covering at least the sidewalls of the second anti-spacer material layer; a step of removing at least a portion of the second anti-spacer material layer to form a second trench along the sidewalls of the second structure and the sidewalls of the second filler material, wherein the second trench defines a second etching pattern; and a step of transferring the second etching pattern into the memory layer and removing the material on the memory layer, wherein the step of performing the first anti-spacer forming process comprises covering the first structure with a filler material; A method comprising the step of annealing the substrate to form the first anti-spacer material layer along the side of the first structure, wherein the first anti-spacer material layer is formed from the first structure and the filler material. Claim 8 A method according to claim 7, wherein the first anti-spacer forming process comprises an external diffusion process, and a portion of the filler material is converted to form the first anti-spacer material layer. Claim 9 A method according to claim 7, wherein the step of performing the first anti-spacer forming process further comprises the step of exposing the outer surface of the first anti-spacer material layer using a controlled recess etching process. Claim 10 A method according to claim 1, wherein the step of removing at least a portion of the first anti-spacer material layer comprises the step of exposing the substrate to a solvent to selectively remove the first anti-spacer material layer formed by self-alignment on the first structure. Claim 11 A method for patterning a substrate, wherein the pattern formed by the patterning comprises a row of parallel final trenches having a first pitch, and the method comprises the steps of: forming a first hard mask layer on a layer to be patterned in the substrate; forming a first stencil trench on the first hard mask layer having a pitch equal to twice the first pitch, wherein each trench of the first stencil trench has a first width; forming a first hard mask trench pattern by etching the first hard mask layer using the first stencil trench as an etching mask; forming a first block mask on the first hard mask layer, wherein the first block mask covers a portion of the first hard mask trench to form a first etching pattern on the layer to be patterned; transferring the first etching pattern to the layer to be patterned to form a first group of final trenches, and the first block mask and the A method for patterning a substrate, comprising: a step of removing a first hard mask layer; and a step of transferring a second etching pattern to a layer to be patterned to form a second group of final trenches, wherein the second group of final trenches and the first group of final trenches collectively form a final trench pattern having a first pitch, and all of the final trenches have the same first width. Claim 12 In paragraph 11, the method wherein the first width is equal to half of the first pitch. Claim 13 In claim 11, the step of forming the first stencil trench comprises: forming a first mandrel pattern on the first hard mask layer, wherein the first mandrel pattern is a row of mandrels having four times the first pitch; forming a first interlocking pattern of rows of alternating mandrels and filler lines separated by an anti-spacer material from the first mandrel pattern, wherein the filler lines and the anti-spacer material are formed by self-aligning to the mandrels, and each mandrel and each filler line of the first interlocking pattern has a combined width equal to three times the first width; and selectively removing the anti-spacer material from the first interlocking pattern to form the first stencil trench. Claim 14 In claim 11, before transferring the second etching pattern to the layer to be patterned, the method comprises: forming a second hard mask layer on the final trench of the first group and on the layer to be patterned within the substrate; forming a second stencil trench on the first hard mask layer having a pitch equal to twice the first pitch, wherein each trench of the second stencil trench has the first width, and the second stencil trench is formed by self-aligning to the mandrel of the second mandrel pattern, and the second mandrel pattern is formed shifted relative to the first mandrel pattern on the first hard mask layer by a distance equal to the first pitch; and forming a second hard mask trench pattern by etching the second hard mask layer using the second stencil trench as an etching mask. A method comprising the step of forming a second block mask on the second hard mask layer, wherein the second block mask covers a portion of the second hard mask trench to form a second etching pattern on the layer to be patterned. Claim 15 A method for designing a reticle set, wherein the method comprises the step of having a final design including a line-and-space (L / S) pattern having a final pitch; and includes the step of decomposing the final design into a first reticle design and a second reticle design, wherein the first reticle design and the second reticle design are part of a reticle design for a reticle set for quadruple patterning through an anti-spacer self-aligned lithography-etching-lithography-etching (AS-SALELE) process, wherein the first reticle design is configured to pattern a first row of mandrels having a mandrel pitch equal to four times the final pitch, and the second reticle design is configured to pattern a second row of mandrels having the same mandrel pitch, wherein the arrangement of the second row of mandrels is shifted relative to the first row of mandrels by a distance equal to the final pitch in a direction parallel to the mandrels of the row, and wherein the first reticle design and the second reticle design are configured to form an L / S pattern having the final pitch on a substrate, and the method also comprises the final design as a first block reticle A method for designing a reticle set, comprising the step of decomposing into a design for a first block reticle and a second block reticle, wherein the first block reticle and the second block reticle are part of the reticle set, the first block reticle is configured to form a first block mask, and the second block reticle is configured to form a second block mask. Claim 16 In paragraph 15, the space of the above L / S pattern has a width equal to half of the final pitch. Claim 17 delete Claim 18 A method according to claim 15, wherein the first block mask comprises a plurality of first blocks configured to block a first hard mask trench configured to be formed on the side of one of the first row of mandrels, and the second block mask comprises a plurality of second blocks configured to block a second hard mask trench configured to be formed on the side of one of the second row of mandrels. Claim 19 In paragraph 18, a method in which one of the first blocks is spaced apart from an adjacent second block by a space greater than half of the final pitch. Claim 20 In paragraph 18, a method wherein one of the first blocks is spaced apart from an adjacent one of the first blocks by a space greater than half of the final pitch.

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