Photolithography Patterning Method

Abstract

A patterning method according to an embodiment of the present invention includes the steps of forming a first photoresist layer on a substrate, performing a first divided exposure on the first photoresist layer with a first exposure energy equal to or greater than a threshold energy using a reticle having lines and spaces of a mask pattern and an exposure device, and moving the reticle to a position equal to or less than the line width of the mask pattern and performing a second divided exposure on the first photoresist layer with a second exposure energy equal to or greater than a threshold energy using the reticle to form a photoresist pattern, wherein a spatial distribution of the first exposure energy is superimposed on a spatial distribution of the second exposure energy.

Description

[Technical field]

[0001] The present invention relates to photolithographic patterning methods, and more particularly to fine linewidth patterning methods that reduce the linewidth of a photoresist pattern. [Background technology]

[0002] Photolithography is a technique for transferring a mask pattern from a reticle onto a photoresist. The limiting resolution of the photoresist pattern depends on the resolution of the reticle and the wavelength of the exposure tool.

[0003] Generally, in double patterning technology, after photolithography process, the substrate is unloaded from the exposure equipment, the next process is carried out, and then the substrate is loaded into the exposure equipment again to carry out the photolithography process, which increases the limit resolution of the photoresist pattern. DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0004] The technical problem to be solved by the present invention is to increase the pattern density beyond the resolution of the exposure tool. The technical problem to be solved by the present invention is to form lines and spaces at 20 nm level using ArF immersion equipment. [Means for solving the problem]

[0005] A patterning method according to an embodiment of the present invention includes the steps of forming a first photoresist layer on a substrate, performing a first divided exposure on the first photoresist layer with a first exposure energy equal to or greater than a threshold energy using a reticle having lines and spaces of a mask pattern and an exposure device, and moving the reticle to a position equal to or less than the line width of the mask pattern and performing a second divided exposure on the first photoresist layer with a second exposure energy equal to or greater than a threshold energy using the reticle to form a photoresist pattern, wherein a spatial distribution of the first exposure energy is superimposed on a spatial distribution of the second exposure energy.

[0006] In one embodiment of the present invention, the first exposure energy is between 125% and 155% of the threshold energy.

[0007] In one embodiment of the present invention, the reticle movement amount is 10% to 20% of the line width of the mask pattern.

[0008] In one embodiment of the present invention, the exposure equipment is an ArF immersion equipment, the line width of the mask pattern is 40 nm, and the space width of the mask pattern is 40 nm.

[0009] In one embodiment of the present invention, the method further includes developing the first photoresist layer to form a patterned first photoresist pattern, and the first photoresist pattern has a line width of less than 33 nm.

[0010] In one embodiment of the present invention, the first photoresist pattern has a line width of about 20 nm and a space width of about 60 nm.

[0011] In one embodiment of the present invention, the method further includes developing the first photoresist layer to form a patterned first photoresist pattern, and an aspect ratio, which is a ratio of a height of the first photoresist pattern to a line width of the first photoresist pattern, is 4 or less.

[0012] In one embodiment of the present invention, the first exposure energy is the same as the second exposure energy, and the first exposure energy is 143% of a threshold energy.

[0013] In one embodiment of the present invention, the method further includes developing the first photoresist layer to form a patterned first photoresist pattern, wherein the first exposure energy and the second exposure energy are greater than or equal to a threshold energy, and the sum of the first exposure energy and the second exposure energy is 260% to 300% of the threshold energy.

[0014] According to an embodiment of the present invention, a patterning method includes the steps of forming a hard mask layer on a substrate, forming a first photoresist layer on the hard mask layer, performing a first exposure on the first photoresist layer with a first exposure energy equal to or greater than a threshold energy using a reticle having lines and spaces of a mask pattern and an exposure device, moving the reticle to a position below a line width of the mask pattern and performing a second exposure on the first photoresist layer with a second exposure energy equal to or greater than a threshold energy using the reticle, developing the first photoresist layer to form a first photoresist pattern, and etching the first photoresist pattern with an etching mask. the first photoresist pattern is removed, and then a second photoresist layer is formed on the preliminary hard mask pattern; the reticle is moved to 1 / 2 the pitch of the mask pattern based on the preliminary hard mask pattern, and a third divided exposure is performed on the second photoresist layer with a third exposure energy equal to or greater than a threshold energy using the reticle and the exposure equipment; and the reticle is moved to a position equal to or less than a line width of the mask pattern, and a fourth divided exposure is performed on the second photoresist layer with a fourth exposure energy equal to or greater than a threshold energy using the reticle.

[0015] In one embodiment of the present invention, the method further includes developing the second photoresist layer to form a second photoresist pattern; and etching the substrate using the second photoresist pattern and the preliminary hard mask pattern as an etching mask.

[0016] In an embodiment of the present invention, the method further includes developing the second photoresist layer to form a second photoresist pattern, etching the preliminary hard mask pattern using the second photoresist pattern as an etching mask to form a main hard mask pattern, and removing the second photoresist pattern, and etching the substrate using the main hard mask pattern as an etching mask. Effect of the Invention

[0017] The patterning method according to an embodiment of the present invention can form a pattern of 38 nm or less, which is the resolution limit of ArF immersion equipment. The patterning method according to an embodiment of the present invention can form a line pattern of 20 nm level using ArF immersion equipment.

[0018] The patterning method according to an embodiment of the present invention can form a 20 nm level line and 20 nm level space pattern using an ArF immersion equipment. BEST MODE FOR CARRYING OUT THEINVENTION

[0019] Due to the process limitations of single patterning, a method to increase the pattern density is required. Single patterning has a limit to the pattern pitch due to the resolution limit of the photoresist pattern. Multi-patterning is a method to increase the pattern density, and includes the LLE (Litho-Lithi-Etch) technique, which performs two exposures, the LELE (Litho-Etch-Litho-Etch) technique, which performs two exposures and etchings using a hard mask, and the SASP (Self-Aligned Double Patterning) technique, which uses a sidewall spacer.

[0020] The LLE (Litho-Litho-Etch) technique uses a mask pattern with different line and space widths and a certain pitch to perform a first patterning exposure, then moves the mask pattern a distance of half the pitch and performs a second patterning exposure. This allows fine patterns to be created. The first patterning exposure does not spatially overlap with the second patterning exposure.

[0021] According to an embodiment of the present invention, a photoresist pattern with suppressed undercut is formed by performing split exposure before and after a first fine movement using a mask pattern having the same line width and space width. The first split exposure before the fine movement forms a photoresist preliminary pattern in the photoresist. The fine movement is 1 / 10 of the line width of the mask pattern. After the fine movement, the second split exposure is spatially overlapped with the photoresist preliminary pattern to form a first photoresist pattern. The first split exposure and the second split exposure split an over-doze expose energy that is greater than a threshold energy. The energy spatial distribution of the first split exposure is spatially overlapped with the energy spatial distribution of the second split exposure and the fine movement amount. Thus, the maximum value of the energy spatial distribution of the first split exposure and the maximum value of the energy spatial distribution of the second split exposure are separated by the fine movement amount. The energy spatial distribution of the first split exposure and the energy spatial distribution of the second split exposure form a composite energy spatial distribution. The photoresist layer is activated in response to the composite energy spatial distribution. As a result, the composite energy spatial distribution forms various types of energy spatial distribution, suppresses undercut caused by light reflection at the bottom of the photoresist layer, and contributes to activation of the photoresist layer.

[0022] The fine movement division exposure according to an embodiment of the present invention forms a fine pattern while suppressing the collapse of the photoresist pattern.

[0023] The fine movement division exposure of the present invention is applied to the LLE (Litho-Lithi-Etch) technique, the LELE (Litho-Etch-Litho-Etch) technique, which uses a hard mask to perform exposure and etching twice, and the SASP (Self-Aligned Double Patterning) technique, which uses a sidewall spacer, making multiple patterning possible.

[0024] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein, and may be embodied in different forms. Rather, the embodiments described herein are provided so that the disclosure will be thorough and complete, and will fully convey the concept of the present invention to those skilled in the art. In the drawings, the dimensions of components are exaggerated for clarity. The same reference numerals are used throughout the specification to refer to the same components.

[0025] FIG. 1A is a conceptual diagram illustrating a photolithography process having an over-dose that does not induce destruction of a photoresist pattern.

[0026] FIG. 1B is a conceptual diagram showing a photoresist pattern after the exposure step and development of FIG. 1A.

[0027] 1A and 1B, a bottom anti-reflection coating (BARC) 112 is coated on a substrate 110, and a photoresist layer 114 is formed on the bottom anti-reflection coating 112. In a positive photoresist, an area irradiated with energy exceeding an open threshold energy in a single exposure becomes a space area after development, and an area irradiated with energy below the open threshold energy becomes a line area after development.

[0028] The line width LW and space width SW of the mask pattern of the reticle 116 are each 40 nm. Thus, the pitch of the mask pattern is 80 nm. The threshold exposure energy of the exposure tool 120 is 14 mJ. For example, when the exposure energy of the exposure tool 120 is 20 mJ, the line width and space width of the photoresist pattern 114a are each 40 nm. When the line width of the mask pattern and the line width of the photoresist pattern are the same, the exposure energy (20 mJ) is the optimal energy.

[0029] 1A, when the exposure energy 10 of the exposure tool 120 is 28.5 mJ, the line width of the photoresist pattern 114a is about 35 nm, and the space width is about 45 nm. In the energy spatial distribution, the energy exceeding the threshold energy is partially offset by the bottom anti-reflective coating 112, but affects the side of the photoresist pattern.

[0030] FIG. 2A is a conceptual diagram illustrating a photolithography process with an over-dose energy that induces the destruction of a photoresist pattern.

[0031] FIG. 2B is a conceptual diagram illustrating the photoresist pattern of FIG. 2A exposed with an exposure energy of 37 mJ.

[0032] FIG. 2C is an SEM photograph showing the photoresist pattern of FIG. 2A exposed with an exposure energy of 37 mJ.

[0033] As shown in FIGS. 2A, 2B and 2C, a bottom antireflection coating (BARC) 112 is coated on a substrate 110, and a photoresist layer 114 is formed on the bottom antireflection coating.

[0034] The line width and space width of the mask pattern of the reticle 120 are 40 nm, respectively. Thus, the pitch of the mask pattern is 80 nm. The threshold exposure energy of the exposure tool 200 is 14 mJ. When the exposure energy 11 of the exposure tool is 37 mJ, the line width and space width of the photoresist pattern 114a are 33 nm and 47 nm, respectively. When the exposure energy is 37 mJ or more, the energy reflected from the bottom anti-reflective coating 112 increases the energy at the bottom end of the photoresist pattern 114a, so that the bottom of the photoresist pattern is scraped off, and the lower portion of the photoresist pattern is tilted or peeled off. As a result, the photoresist pattern 114a has an undercut and collapses or peels off.

[0035] That is, the exposure energy is provided excessively to a level of 37 mJ, exceeding the optimum energy of 20 mJ. In this case, based on the line width of the mask pattern of 40 nm, the exposure energy of 37 mJ reduces the line width of the photoresist pattern 114a to 33 nm. However, if the exposure is performed with an exposure energy exceeding 37 mJ, the photoresist pattern 114a collapses due to undercutting of the lower side after development.

[0036] In an over-doze energy process in which the exposure energy exceeds the optimum energy, the line width of the photoresist pattern can only be 33 nm based on the line and space width of the mask pattern of 40 nm. This over-doze process occurs because a large amount of energy is reflected from the lower anti-reflective coating 112. The reflected energy removes the lower portion of the lower anti-reflective coating 112, and the photoresist pattern 114a cannot stand vertically.

[0037] FIG. 3A is a conceptual diagram illustrating a first divided exposure of fine movement divided exposure according to one embodiment of the present invention.

[0038] FIG. 3B is a conceptual diagram illustrating the second divided exposure of the fine movement divided exposure according to one embodiment of the present invention.

[0039] FIG. 3C is a conceptual diagram illustrating the first divided exposure and the second divided exposure of the fine movement divided exposure according to an embodiment of the present invention.

[0040] FIG. 3D is a conceptual diagram illustrating a photoresist pattern formed by the fine movement division exposure of FIG. 3C.

[0041] As shown in Figures 3A to 3D, a patterning method according to one embodiment of the present invention includes the steps of forming a first photoresist layer 114 on a substrate 110, performing a first divided exposure on the first photoresist layer 114 at a first exposure energy 21 equal to or greater than a threshold energy using a reticle 116 having lines and spaces of a mask pattern and an exposure device 120, and moving the reticle 116 to a position equal to or less than the line width LW of the mask pattern and performing a second divided exposure on the first photoresist layer 114 at a second exposure energy 22 equal to or greater than a threshold energy using the reticle 116.

[0042] The exposure equipment 120 is an ArF immersion equipment, a KrF equipment, or an EUV equipment. The wavelength of the ArF immersion equipment is 193 nm.

[0043] In the reticle 116, the ratio of the size of the photoresist pattern 114a to the size of the mask pattern of the reticle is 1:1 to 1:10. The reticle 112 has lines and spaces of a mask pattern, and the line width ratio of the lines and spaces is 1:1. That is, the line width LW of the mask pattern is 40 nm, and the space width SW of the mask pattern is 40 nm.

[0044] The substrate 110 is a semiconductor substrate, which includes an etching layer for etching.

[0045] A bottom anti-reflective coating 112 is disposed on the substrate 110. A bottom anti-reflective coating 112 (BARC) is disposed under the first photoresist layer 114 to reduce reflection of the exposure beam.

[0046] The first photoresist layer 114 is a positive photoresist or a negative photoresist, and has a thickness of 50 nm to 90 nm.

[0047] The substrate 110 coated with the first photoresist layer 114 is loaded into an exposure tool and aligned with the reticle 116 .

[0048] A first divided exposure is performed on the first photoresist layer 114 at a first exposure energy 21 that is equal to or greater than a threshold energy using a reticle 116 having lines and spaces of a mask pattern and exposure equipment 120. The threshold energy is 14 mJ for the ArF immersion equipment and the first photoresist layer 114. The first exposure energy 21 is 20 mJ. At an exposure energy of 20 mJ, the ratio of the line width of the photoresist pattern to the line width of the mask pattern of the reticle is 1:1.

[0049] The first exposure energy 21 is between 125% and 155% of the threshold energy (14 mJ). The photoresist layer exposed to a first exposure energy 21 above the threshold energy of 14 mJ is chemically altered and activated.

[0050] After the first divided exposure, the reticle is finely moved to a position equal to or smaller than the line width of the mask pattern. The reticle movement amount Δ is 10% to 20% of the line width (LW=40 nm) of the mask pattern. Specifically, when the line width of the mask pattern is 40 nm, the reticle movement amount Δ is 4 nm.

[0051] After the reticle is finely moved, a second divided exposure is performed on the first photoresist layer 114 using the reticle at a second exposure energy 22 that is equal to or greater than the threshold energy. The second exposure energy 22 of the second divided exposure is 125% to 155% of the threshold energy. Specifically, the second exposure energy 22 is 20 mJ.

[0052] As shown in FIG. 3C, the spatial distribution of the first exposure energy 21 of the first divided exposure and the spatial distribution of the second exposure energy 22 of the second divided exposure are displayed. Also, the sum 20 (SUM) of the spatial distribution of the first exposure energy and the spatial distribution of the second exposure energy is displayed. The maximum value of the sum (SUM) is at the 37 mJ level. Even if there is a time difference between the first divided exposure and the second divided exposure, the chemical reaction of the photoresist is cumulative.

[0053] In the fine movement divided exposure of the present invention, the photoresist layer is not activated when the sum (SUM) of the exposure energies is less than the threshold energy (14 mJ). According to experimental results, the fine movement divided exposure adjusts the amount of reflection of the exposed light to form a photoresist pattern with less damage to the bottom of the lower anti-reflective coating 112. This suppresses the slope shape of the bottom of the photoresist pattern. The fine movement amount Δ of the reticle is optimally 10 to 20% of the line width LW of the mask pattern. The first exposure energy 21 and the second exposure energy are greater than the threshold energy, and the sum (SUM) of the first exposure energy and the second exposure energy 22 is 260% to 300% of the threshold energy.

[0054] The energy that is insufficient in the first divided exposure is added to the energy of the second divided exposure to activate the photoresist layer. However, the energy reflected in the first divided exposure is not added to the energy reflected in the second divided exposure. The fine movement divided exposure method controls the exposure energy and the energy spatial distribution more precisely than a single overexposure. The reflected energy reduced by the fine movement divided exposure suppresses the collapse of the photoresist pattern. As a result, compared to the minimum line width of 33 nm that can be achieved by a single overexposure, the present invention reduces the minimum line width to the 20 nm level. When the line width of the mask pattern is 40 nm and the space width is 40 nm, the line width of the photoresist pattern 114a is 20 nm and the space width is 60 nm. The line to space width ratio of the photoresist pattern 114a is 1:3.

[0055] According to a modified embodiment of the present invention, a fine movement three-division exposure is applied. Specifically, the fine movement three-division exposure includes a first division exposure, a first fine movement of the reticle, a second division exposure, a second fine movement of the reticle, and a third division exposure. The energy of the first division exposure, the second division exposure, and the third division exposure is the same.

[0056] FIG. 4 is a SEM photograph taken by fine movement division exposure according to one embodiment of the present invention.

[0057] FIG. 5 shows the divided exposure energy and the fine movement amount of the fine movement divided exposure according to one embodiment of the present invention.

[0058] FIG. 6A is a CD-SEM photograph of FIG.

[0059] FIG. 6B is an enlarged SEM photograph of FIG.

[0060] 4 and 5, the exposure energy 21, 22 of the first divided exposure or the second divided exposure is at a level of 125% to 155% (18mJ to 22mJ) of the photoresist opening threshold energy (14mJ). The shift value of the mask pattern or reticle is 10% to 20% (4nm to 8nm) of the line width (40nm) of the mask pattern.

[0061] In this experiment, ArF immersion equipment was used. The thickness of the photoresist layer was 60 nm, the illumination system was Dipole 35Y, and the numerical aperture (NA) was 1.35. The mask fine movement amount Δ was 4 nm. The reticle mask pattern had a line width of 40 nm and a space width of 40 nm. The exposure energy 21 of the first divided exposure was 20 mJ, and the exposure energy 22 of the second divided exposure was 20 mJ. The photoresist pattern had a line width of 23 nm, a photoresist pattern height of 61.5 nm, and a photoresist pattern pitch of 80.5 nm.

[0062] In order to form a fine pattern of 33 nm or less in an ArF exposure tool, the present invention proposes a fine movement division exposure technology. With the wafer fixed, the position of the mask pattern of the reticle is finely moved perpendicularly to the line extension direction, and the exposure energy is divided before and after the fine movement to perform division exposure to form a fine pattern. That is, the total exposure energy is divided into a first exposure energy 21 and a second exposure energy 22 in terms of time. In addition, the spatial distribution of the first exposure energy 21 and the spatial distribution of the second exposure energy 22 are superimposed on each other by the fine movement amount Δ. For this purpose, the substrate 110 and the reticle 116 are fixed on the stage of the exposure tool. One exposure is performed before and one after the reticle 116 coordinates are finely changed. This allows exposure without overlay error. The fine movement division exposure can suppress the collapse of the photoresist pattern.

[0063] Fine movement divided exposure (or fine movement multiple exposure) according to one embodiment of the present invention selects an exposure energy of an overexposure condition that causes the photoresist pattern to collapse. If a single exposure is performed using the exposure energy of the overexposure condition, the photoresist pattern will collapse. For example, the exposure energy of the overexposure condition is 37 mJ or more. The exposure energy of the overexposure condition is divided into two in time, and the divided exposure energies are finely moved spatially and superimposed. The maximum value of the spatial distribution of the combined exposure energy is 37 mJ or more. The spatial distribution of the combined exposure energy is different from the spatial distribution of the overexposure condition. Furthermore, the fine movement divided exposure changes the energy distribution of the reflected light.

[0064] Experimental results show that the photoresist pattern collapses during single exposure of 37 mJ or more, but does not collapse during fine movement divided exposure.

[0065] The photoresist layer is subjected to a first divided exposure, and then the wafer is not unloaded from the exposure tool, and the mask coordinates are finely shifted before the second exposure.

[0066] Due to the characteristics of the photoresist of the present invention, a pattern having a line width of 20 nm is realized by an ArF immersion process. The resolution limit of the ArF immersion process is 38 nm. The patterning method of the present invention realizes a 20 nm pattern, which is less than the resolution limit of the ArF immersion process.

[0067] FIG. 7 is a SEM photograph showing a patterning result depending on the thickness of a photoresist layer according to an embodiment of the present invention.

[0068] 7, (a) is the case where the height of the photoresist layer 114 is 90 nm, and (b) is the case where the height of the photoresist layer 114 is 60 nm. The process conditions are the same as those in FIG. 4 except for the thickness of the photoresist layer.

[0069] When the height of the photoresist layer 114 is 90 nm, the aspect ratio is 4.5, and localized pattern collapse is found after development using the spin develop method. However, when the height of the photoresist layer 114 is 60 nm, the aspect ratio is 3, and no pattern collapse is found after development using the spin develop method. The aspect ratio is the height of the photoresist layer 114 divided by the line width (20 nm).

[0070] Therefore, the height of the photoresist needs to be reduced to 90 nm or less to reduce the aspect ratio, i.e., the aspect ratio is 4 or less.

[0071] With a photoresist thickness of 90 nm, line widths of 23 nm are possible. With a photoresist thickness of 60 nm, line widths of 21 nm are possible. By reducing the photoresist thickness, line widths below 20 nm are also possible.

[0072] Also, if the development method is changed from the spin develop method to the stop method, patterning is possible even at a thickness of 90 nm.

[0073] The fine movement division exposure of the present invention is applied to a double patterning process using the LELE process.

[0074] 8A to 8G are diagrams illustrating a double patterning method according to an embodiment of the present invention.

[0075] 8A to 8G, a double patterning method according to an embodiment of the present invention includes the steps of forming a hard mask layer 111 on a substrate 110, forming a first photoresist layer 114 on the hard mask layer 111, performing a first division exposure on the first photoresist layer 114 at a first exposure energy 21 equal to or greater than a threshold energy using a reticle 116 having lines and spaces of a mask pattern and an exposure device 120, moving the reticle to a position equal to or less than the line width of the mask pattern and performing a second division exposure on the first photoresist layer at a second exposure energy equal to or greater than a threshold energy using the reticle, developing the first photoresist layer to form a first photoresist pattern 114a, and forming a second photoresist pattern 114b on the first photoresist layer 114. 14a as an etching mask to etch the hard mask layer 111 to form a preliminary hard mask pattern 111a; removing the first photoresist pattern 114a and then forming a second photoresist layer 214 on the preliminary hard mask pattern 111a; moving the reticle to 1 / 2 the pitch of the mask pattern based on the preliminary hard mask pattern 111a, and performing a third divided exposure on the second photoresist layer with a third exposure energy equal to or greater than a threshold energy using the reticle 116 and the exposure equipment 120; and moving the reticle to a position equal to or less than the line width of the mask pattern, and performing a fourth divided exposure on the second photoresist layer with a fourth exposure energy equal to or greater than a threshold energy using the reticle.

[0076] As shown in Figure 8A, a substrate 110 is a semiconductor substrate. The substrate includes an etching layer for etching. A hard mask layer 111 is formed on the substrate. The hard mask layer 111 is an amorphous carbon layer.

[0077] A bottom anti-reflective coating 112 is formed on the hard mask layer. The bottom anti-reflective coating 112 (BARC) is disposed under the first photoresist layer 114 to reduce reflection of the exposure beam.

[0078] A first photoresist layer 114 is formed on the bottom anti-reflective coating 112. The first photoresist layer 114 is a positive photoresist. The thickness of the first photoresist layer 114 is 50 nm to 90 nm.

[0079] A first divided exposure is performed on the first photoresist layer 114 using a reticle 116 having lines and spaces of a mask pattern and an exposure device 120 with a first exposure energy 21 that is equal to or greater than a threshold energy.

[0080] The reticle is moved to a position equal to or smaller than the line width of the mask pattern, and a second divided exposure is performed on the first photoresist layer using the reticle at a second exposure energy equal to or greater than a threshold energy. The amount of movement Δ of the reticle is 10% to 20% (4 nm to 8 nm) of the line width (40 nm) of the mask pattern.

[0081] 8B, the first photoresist layer is developed to form a first photoresist pattern 114a, which is performed using a spin developing device.

[0082] 8C, the hard mask layer 111 is etched using the first photoresist pattern 114a as an etching mask to form a preliminary hard mask pattern 111a, using an anisotropic plasma etching device.

[0083] 8D, after removing the first photoresist pattern 114a, a second photoresist layer 214 is formed on the preliminary hard mask pattern 111a. A lower reflective coating layer is disposed under the second photoresist layer 214. The second photoresist layer 214 has the same material and structure as the first photoresist layer 114.

[0084] As shown in FIG. 8E, the reticle 116 is moved to 1 / 2 the pitch of the mask pattern based on the preliminary hard mask pattern 111a, and a third divided exposure is performed on the second photoresist layer 214 using the reticle 116 and the exposure equipment 120 with a third exposure energy 21' that is greater than or equal to the threshold energy. The reticle 216 is moved to a position below the line width of the mask pattern, and a fourth divided exposure is performed on the second photoresist layer 214 using the reticle at a fourth exposure energy 22' that is equal to or greater than the threshold energy.

[0085] As shown in FIG. 8F, the second photoresist layer is developed to form a second photoresist pattern 214a.

[0086] 8G, the substrate 110 is etched using the second photoresist pattern 214a and the preliminary hard mask pattern 111a as an etching mask, whereby the substrate is double-patterned with a line width of 20 nm, and then the second photoresist pattern 214a and the preliminary hard mask pattern 111a are removed.

[0087] 9A to 9H are views illustrating a double patterning method according to an embodiment of the present invention.

[0088] 9A to 9H, a double patterning method according to an embodiment of the present invention includes the steps of forming a hard mask layer 111 on a substrate 110, forming a first photoresist layer 114 on the hard mask layer 111, performing a first division exposure on the first photoresist layer 114 at a first exposure energy 21 equal to or greater than a threshold energy using a reticle 116 having lines and spaces of a mask pattern and an exposure device 120, moving the reticle to a position equal to or less than the line width of the mask pattern and performing a second division exposure on the first photoresist layer at a second exposure energy equal to or greater than a threshold energy using the reticle, developing the first photoresist layer to form a first photoresist pattern 114a, and forming a second photoresist pattern 114b on the first photoresist layer 114. 14a as an etching mask to etch the hard mask layer 111 to form a preliminary hard mask pattern 111a; removing the first photoresist pattern 114a and then forming a second photoresist layer 214 on the preliminary hard mask pattern 111a; moving the reticle to 1 / 2 the pitch of the mask pattern based on the preliminary hard mask pattern 111a, and performing a third divided exposure on the second photoresist layer with a third exposure energy equal to or greater than a threshold energy using the reticle 116 and the exposure equipment 120; and moving the reticle to a position equal to or less than the line width of the mask pattern, and performing a fourth divided exposure on the second photoresist layer with a fourth exposure energy equal to or greater than a threshold energy using the reticle.

[0089] As shown in Figure 9A, a substrate 110 is a semiconductor substrate. The substrate includes an etching layer for etching. A hard mask layer 111 is formed on the substrate. The hard mask layer 111 is an amorphous carbon layer.

[0090] A bottom anti-reflective coating 112 is formed on the hard mask layer. The bottom anti-reflective coating 112 (BARC) is disposed under the first photoresist layer 114 to reduce reflection of the exposure beam.

[0091] A first photoresist layer 114 is formed on the bottom anti-reflective coating 112. The first photoresist layer 114 is a negative photoresist. The first photoresist layer 114 has a thickness of 50 nm to 90 nm.

[0092] A first divided exposure is performed on the first photoresist layer 114 using a reticle 116 having lines and spaces of a mask pattern and an exposure device 120 with a first exposure energy 21 that is equal to or greater than a threshold energy.

[0093] The reticle is moved to a position equal to or smaller than the line width of the mask pattern, and a second divided exposure is performed on the first photoresist layer using the reticle at a second exposure energy equal to or greater than a threshold energy. The amount of movement Δ of the reticle is 10% to 20% (4 nm to 8 nm) of the line width (40 nm) of the mask pattern.

[0094] 9B, the first photoresist layer is developed to form a first photoresist pattern 114a, which is performed using a spin developing device.

[0095] 9C, the hard mask layer 111 is etched using the first photoresist pattern 114a as an etching mask to form a preliminary hard mask pattern 111a, using an anisotropic plasma etching device.

[0096] 9D, after removing the first photoresist pattern 114a, a second photoresist layer 214 is formed on the preliminary hard mask pattern 111a. A lower reflective coating layer 212 is disposed under the second photoresist layer 214. The second photoresist layer 214 has the same material and structure as the first photoresist layer 114.

[0097] Using the preliminary hard mask pattern 111a as a reference, the reticle 116 is moved by 1 / 2 the pitch of the mask pattern, and a third divided exposure is performed on the second photoresist layer 214 using the reticle 116 and the exposure equipment 120 with a third exposure energy 21' that is equal to or greater than a threshold energy.

[0098] The reticle 216 is moved to a position below the line width of the mask pattern, and a fourth divided exposure is performed on the second photoresist layer 214 using the reticle at a fourth exposure energy 22' that is equal to or greater than the threshold energy.

[0099] As shown in FIG. 9E, the second photoresist layer 214 is developed to form a second photoresist pattern 214a.

[0100] As shown in FIG. 9F, the preliminary hard mask pattern 111a is etched using the second photoresist pattern 214a as an etching mask to form a main hard mask pattern 111b.

[0101] 9G, the second photoresist pattern 214a is removed, and the substrate 110 is etched using the main hard mask pattern 111b as an etching mask, so that the substrate is double-patterned to have a line width of 20 nm.

[0102] As shown in FIG. 9H, the main hard mask pattern 111b is removed.

[0103] Although the present invention has been illustrated and described with respect to specific preferred embodiments, the present invention is not limited to such embodiments and includes all various forms of embodiments that can be implemented by a person having ordinary skill in the art to which the invention pertains without departing from the technical spirit of the present invention as claimed in the claims. [Brief description of the drawings]

[0104] [Figure 1A]FIG. 2 is a conceptual diagram illustrating a photolithography process having an overdose that does not induce destruction of a photoresist pattern. [Figure 1B] FIG. 1B is a conceptual diagram showing a photoresist pattern after the exposure step and development of FIG. 1A. [Figure 2A] FIG. 2 is a conceptual diagram illustrating a photolithography process having an over-dose energy that induces the destruction of a photoresist pattern. [Figure 2B] FIG. 2B is a conceptual diagram illustrating the photoresist pattern of FIG. 2A exposed with an exposure energy of 37 mJ. [Figure 3A] FIG. 4 is a conceptual diagram illustrating a first divided exposure of fine movement divided exposure according to an embodiment of the present invention. [Figure 3B] FIG. 11 is a conceptual diagram illustrating a second divided exposure of the fine movement divided exposure according to an embodiment of the present invention. [Figure 3C] 4A to 4C are conceptual diagrams illustrating a first divided exposure and a second divided exposure of fine movement divided exposure according to an embodiment of the present invention. [Figure 3D] FIG. 3D is a conceptual diagram illustrating a photoresist pattern formed by the fine movement division exposure of FIG. 3C. [Figure 4] 1 is a SEM photograph taken by fine movement division exposure according to an embodiment of the present invention. [Diagram 5] 4 shows the divided exposure energy and the fine movement amount of fine movement divided exposure according to one embodiment of the present invention. [Figure 6A] The CD-SEM photograph of FIG. [Figure 6B] FIG. 5 is an enlarged SEM photograph of FIG. [Figure 7] 4 is a SEM photograph showing a patterning result depending on a thickness of a photoresist layer according to an embodiment of the present invention. [Figure 8A] 1 is a diagram illustrating a double patterning method according to an embodiment of the present invention; [Figure 8B] 1 is a diagram illustrating a double patterning method according to an embodiment of the present invention; [Figure 8C]1 is a diagram illustrating a double patterning method according to an embodiment of the present invention; [Figure 8D] 1 is a diagram illustrating a double patterning method according to an embodiment of the present invention; [Figure 8E] 1 is a diagram illustrating a double patterning method according to an embodiment of the present invention; [Figure 8F] 1 is a diagram illustrating a double patterning method according to an embodiment of the present invention; [Figure 8G] 1 is a diagram illustrating a double patterning method according to an embodiment of the present invention; [Figure 9A] 1 is a diagram illustrating a double patterning method according to an embodiment of the present invention; [Figure 9B] 1 is a diagram illustrating a double patterning method according to an embodiment of the present invention; [Figure 9C] 1 is a diagram illustrating a double patterning method according to an embodiment of the present invention; [Figure 9D] 1 is a diagram illustrating a double patterning method according to an embodiment of the present invention; [Figure 9E] 1 is a diagram illustrating a double patterning method according to an embodiment of the present invention; [Figure 9F] 1 is a diagram illustrating a double patterning method according to an embodiment of the present invention; [Figure 9G] 1 is a diagram illustrating a double patterning method according to an embodiment of the present invention; [Figure 9H] 1 is a diagram illustrating a double patterning method according to an embodiment of the present invention;

Claims

1. forming a first photoresist layer on a substrate; performing a first division exposure on the first photoresist layer at a first exposure energy above a threshold energy using a reticle having lines and spaces of a mask pattern and exposure equipment; and performing a second divided exposure on the first photoresist layer using the reticle at a second exposure energy equal to or greater than a threshold energy to form a photoresist pattern, the second divided exposure being performed on the first photoresist layer using the reticle at a second exposure energy equal to or greater than a threshold energy, a spatial distribution of the first exposure energy is superimposed on a spatial distribution of the second exposure energy; The method of claim 1, wherein the first exposure energy is between 125% and 155% of a threshold energy.

2. 2. The patterning method according to claim 1, wherein the amount of movement of the reticle is 10% to 20% of the line width of the mask pattern.

3. The exposure equipment is an ArF immersion equipment, the line width of the mask pattern is 40 nm; 2. The patterning method according to claim 1, wherein the space line width of the mask pattern is 40 nm.

4. The method further includes developing the first photoresist layer to form a patterned first photoresist pattern; 2. The method of claim 1, wherein the first photoresist pattern has a line width of less than 33 nm.

5. The line width of the first photoresist pattern is about 20 nm.

5. The method of claim 4, wherein the space width of the first photoresist pattern is about 60 nm.

6. The method further includes developing the first photoresist layer to form a patterned first photoresist pattern; 2. The method of claim 1, wherein an aspect ratio, which is a ratio of a height of the first photoresist pattern to a line width of the first photoresist pattern, is 4 or less.

7. A method for manufacturing a photoresist film comprising the steps of: forming a first photoresist layer on a substrate; performing a first division exposure on the first photoresist layer at a first exposure energy above a threshold energy using a reticle having lines and spaces of a mask pattern and exposure equipment; and performing a second divided exposure on the first photoresist layer using the reticle at a second exposure energy equal to or greater than a threshold energy to form a photoresist pattern, the second divided exposure being performed on the first photoresist layer using the reticle at a second exposure energy equal to or greater than a threshold energy, a spatial distribution of the first exposure energy is superimposed on a spatial distribution of the second exposure energy; A method of patterning, wherein the first exposure energy is the same as the second exposure energy, the first exposure energy being 143% of a threshold energy.

8. A method for manufacturing a semiconductor device comprising the steps of: forming a first photoresist layer on a substrate; performing a first division exposure on the first photoresist layer at a first exposure energy above a threshold energy using a reticle having lines and spaces of a mask pattern and exposure equipment; and performing a second divided exposure on the first photoresist layer using the reticle at a second exposure energy equal to or greater than a threshold energy to form a photoresist pattern, the second divided exposure being performed on the first photoresist layer using the reticle at a second exposure energy equal to or greater than a threshold energy, a spatial distribution of the first exposure energy is superimposed on a spatial distribution of the second exposure energy; The method further includes developing the first photoresist layer to form a patterned first photoresist pattern; the first exposure energy and the second exposure energy are equal to or greater than a threshold energy; A patterning method according to claim 1, wherein the sum of the first exposure energy and the second exposure energy is 260% to 300% of the threshold energy.

9. forming a hard mask layer over a substrate; forming a first photoresist layer on the hard mask layer; performing a first exposure on the first photoresist layer with a first exposure energy above a threshold energy using a reticle having lines and spaces of a mask pattern and exposure equipment; moving the reticle to a position below a line width of the mask pattern and performing a second exposure on the first photoresist layer using the reticle at a second exposure energy above a threshold energy; developing the first photoresist layer to form a first photoresist pattern; forming a preliminary hard mask pattern by etching the hard mask layer using the first photoresist pattern as an etching mask; forming a second photoresist layer on the preliminary hard mask pattern after removing the first photoresist pattern; moving the reticle to 1 / 2 the pitch of the mask pattern based on the preliminary hard mask pattern, and performing a third division exposure on the second photoresist layer with a third exposure energy equal to or greater than a threshold energy using the reticle and the exposure equipment; and moving the reticle to a position equal to or smaller than a line width of the mask pattern, and performing a fourth divided exposure on the second photoresist layer using the reticle at a fourth exposure energy equal to or greater than a threshold energy, The method of claim 1, wherein the first exposure energy is between 125% and 155% of a threshold energy.

10. developing the second photoresist layer to form a second photoresist pattern; 10. The method of claim 9, further comprising: etching the substrate using the second photoresist pattern and the preliminary hard mask pattern as an etching mask.

11. developing the second photoresist layer to form a second photoresist pattern; forming a main hard mask pattern by etching the preliminary hard mask pattern using the second photoresist pattern as an etching mask; 10. The method of claim 9, further comprising: removing the second photoresist pattern; and etching the substrate using the main hard mask pattern as an etch mask.

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