JP4560066B2 - Pattern formation method - Google Patents

Description

  The present invention relates to a pattern forming method for forming a desired semiconductor pattern by etching after forming a resist pattern.

  The miniaturization of the pattern size of a semiconductor device is remarkable, and it is difficult to form a desired pattern with a sufficient margin only by patterning by lithography. For this reason, the resist is slimmed with an asher (ashing apparatus) after patterning by lithography.

  At the time of slimming, not only the desired pattern but also the peripheral pattern becomes narrow. For this reason, as for patterns other than the fine pattern, a pattern having a thick width in consideration of slimming is previously formed by lithography.

  However, if the slimming amount is large, the width of the pattern other than the fine pattern becomes large, so that the space width with the adjacent pattern becomes narrow, and this time, the dimensions of the pattern other than the fine pattern cannot be formed by lithography. Cases arise.

  In addition, if the width is increased in consideration of the slimming amount in advance, a desired margin may not be obtained.

  Therefore, in such a case, a hard mask process is used. That is, a line pattern portion corresponding to a fine pattern is first formed of a resist, and after slimming by ashing, it is transferred to a hard mask. Thereafter, the first resist pattern is peeled off, a narrow space pattern is formed with the second resist, and the film to be processed is etched using the hard mask and the second resist pattern as a mask. Finally, the second resist pattern and hard mask are removed to obtain a desired pattern. However, as described above, this method has a problem that the number of steps is large and the cost becomes high.

  Further, with the progress of miniaturization, it is impossible to follow this by increasing the NA (numerical aperture) of the lens of the exposure apparatus or shortening the wavelength of the exposure light. In order to solve this, for example, the following approach is taken.

  That is, in order to form a fine pitch pattern that cannot be formed by a single exposure, a 1: 3 L & S resist pattern having a period twice the desired pitch is first formed and then transferred to a hard mask. Thereafter, a resist is applied again, shifted by a desired pitch, and a 1: 3 L & S resist pattern is exposed and developed to form an L & S pattern having a double period finally (for example, Non-Patent Document 1). reference).

  Here, it is only necessary to form a 1: 3 L & S resist pattern, but an L & S pattern having a larger line width than a 1: 3 L & S pattern can widen the process window in the lithography process. For this reason, the line width is first formed thicker than the 1: 3 L & S pattern, and then ashing is performed to form the 1: 3 L & S pattern, which is transferred to the hard mask.

However, since the slimmed resist pattern is once transferred to the hard mask, there are problems that the number of steps is large and the cost is increased.
S. Lee et al. “Double exposure technology using silicon containing materials” Proc. Of SPIE Vol.6153 (2006)

  The present invention provides a pattern forming method capable of reducing the number of steps and the cost when a plurality of patterns that are difficult to form by one exposure coexist.

The pattern forming method according to the first aspect of the present invention includes a step of forming a first resist pattern including a pattern on a film to be processed that includes a pattern that cannot be obtained by lithography patterning unless it is formed by slimming. Slimming the first resist pattern; Step of insolubilizing the first resist pattern so as not to dissolve after the slimming step; On the insolubilized first resist pattern; Forming a second resist pattern including a pattern that cannot be formed in consideration of the amount of slimming or a pattern in which a necessary margin cannot be obtained when slimming is performed on at least one of the film, the first resist pattern, Processing the film to be processed using the second resist pattern as a mask Characterized in that it comprises a that step.

The pattern forming method according to the second aspect of the present invention includes a step of forming a first lower-layer antireflection film on a film to be processed, and lithography unless formed by slimming on the first lower-layer antireflection film. A step of forming a first resist pattern including a pattern that does not allow a necessary margin in patterning by the step, a step of slimming the first resist pattern, and using the slimmed first resist pattern as a mask, A step of processing the first lower-layer antireflection film, a step of insolubilizing the slimmed first resist pattern so as not to dissolve, and after the insolubilization, the first resist pattern and the film to be processed above, forming a second bottom anti-reflective coating, on the second bottom anti-reflection film, considering the slimming min Pattern and that can not be formed, is processed and forming a second resist pattern including a pattern that does not take a necessary margin Doing slimming, the second resist pattern as a mask, the second bottom anti-reflective coating And a step of processing the film to be processed using the first resist pattern or the first lower antireflection film, and the second resist pattern or the processed second lower antireflection film as a mask. It is characterized by including.

The pattern forming method according to the third aspect of the present invention includes a step of forming a lower antireflection film on a film to be processed, and a margin required for patterning by lithography unless it is formed by slimming on the lower antireflection film. A step of forming a first resist pattern including a pattern that cannot be removed, a step of slimming the first resist pattern, and a step of insolubilizing the first resist pattern so as not to dissolve after the slimming step And a pattern that cannot be formed when slimming is taken into account, or a pattern that does not have a necessary margin when slimming is performed, on at least one of the lower antireflection film and the insolubilized first resist pattern. forming a second resist pattern, including, the first resist pattern And using the second resist pattern as a mask, processing the lower antireflection film, and using the first resist pattern, the second resist pattern, or the processed lower antireflection film as a mask. And a step of processing the processed film.

  According to the present invention, it is possible to provide a pattern forming method capable of reducing the number of steps and the cost when a plurality of patterns difficult to be formed by one exposure coexist.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, corresponding portions are denoted by corresponding reference numerals, and the same or similar portions are denoted by the same or similar reference numerals.

(First embodiment)
A pattern forming method according to the first embodiment of the present invention will be described with reference to FIGS.

  In the pattern forming method of the present embodiment, an example will be described in which the number of steps and cost are reduced by overlapping two resist patterns instead of a hard mask.

  In this embodiment, a case where a line pattern including a line corresponding to a gate and a contact fringe are formed in a gate layer will be described as an example.

  FIG. 1 shows a pattern to be finally formed. This is a poly-Si (polysilicon) wiring pattern in which contact fringes 11 and 12 of 100 nm square are attached to a line pattern 10 having a line width of 40 nm. The distance between the two contact fringes 11 and 12 is 100 nm.

  Incidentally, it is difficult to produce an isolated line pattern 10 having a line width of 40 nm by a lithography process. The first reason is that the reticle cannot be manufactured with high accuracy. The second reason is that when a pattern is formed with a positive resist, if the exposure amount is increased, the pattern becomes thin but a margin cannot be obtained. That is, the focus margin and the dose margin cannot be obtained. Further, the head of the pattern is rounded or the remaining film is lost, and there arises a problem that the dimensional variation becomes large at the time of etching.

  Therefore, in order to avoid the above problem, after forming a line 10 having a line width of 80 nm as shown in FIG. 2, the resist line width is reduced to 40 nm by ashing. The slimming amount is 20 nm on one side (40 nm overall). As described above, the line pattern 10 is a fine pattern that cannot be formed with a desired exposure margin by lithography patterning and must be formed by slimming.

  On the other hand, the contact fringes 11 and 12 need to be 140 nm square at the time of patterning in consideration of the 40 nm pattern width being reduced in advance. In this case, the distance between the contact fringes 11 and 12 is 60 nm. However, it is difficult to form a thin space of 60 nm in the lithography process. That is, the contact fringes 11 and 12 are patterns that cannot be formed by performing slimming simultaneously with the line pattern 10.

  Therefore, when this method is used, a 40 nm wide line and a 100 nm wide space cannot be formed simultaneously. On the other hand, the contact fringe pattern needs to have a width of 100 nm in order to conduct the wiring through the contact hole from the upper layer and cannot be reduced.

  Therefore, conventionally, this problem has been avoided by using a hard mask as described below. This conventional method will be described with reference to the top view of FIG. 3 and the flowchart of FIG.

  First, as shown in FIG. 3A as viewed from above, a hard mask material 31 made of SiN is formed on a film to be processed (poly-Si film) 30 (not shown) (step S101 in FIG. 4). On top of this, as shown in FIG. 3B, exposure is performed with normal illumination with NA = 0.915 and σ = 0.3 to form a first resist pattern 32 composed of 80 nm wide lines (steps). S102). Hereinafter, the formation of a resist pattern is a process including resist application, exposure, and development processes.

  Next, as shown in FIG. 3C, the first resist pattern 32 is slimmed with an asher to form a gate pattern so that the line width is 40 nm (step S103).

  Next, the hard mask material 31 is processed using the slimmed first resist pattern 32 as a mask (step S104), and the first resist pattern 32 is peeled off to form a gate pattern made of the hard mask 33. (FIG. 3D) (step S105).

  Thereafter, as shown in FIG. 3E, a second resist pattern 34 is formed as a contact fringe so as to cover the end portion of the hard mask 33 and its surrounding poly-Si film 30 from above (step S106). . The exposure illumination condition at this time is annular illumination with NA = 0.915, σ = 0.9, and ε = 2/3 because there are peripheral patterns. One side of the contact fringe formed by the second resist pattern 34 is 100 nm, and the distance between the two contact fringes is 100 nm.

  Thereafter, the poly-Si film 30 is etched using the second resist pattern 34 and the hard mask 33 as a mask (step S107), the second resist pattern 34 is peeled off (step S108), and the hard mask 33 is peeled off (step S109). ), A desired pattern 35 of the poly-Si film (processed film) was obtained as shown in FIG.

  However, in the processes shown in FIGS. 3 and 4, since a hard mask is used, there are problems that the number of steps is large and costs are increased.

  Therefore, in this embodiment, instead of using a hard mask, a technique of stacking two resist layers is used. The process is shown in the top view of FIG. 5 and the flowchart of FIG.

  First, as shown in FIG. 5A, a first resist pattern 51 is formed on a film to be processed (poly-Si film) 50 (step S201 in FIG. 6). Thereafter, as shown in FIG. 5B, the resist pattern was slimmed with an asher (step S202) to obtain a 40 nm gate pattern.

  Next, insolubilization processing was performed on the first resist pattern 51 so that the first resist pattern 51 was not dissolved when the second resist pattern 52 was patterned (step S203).

  As a method for insolubilization, UV light, DUV light, curing by electron beam irradiation, ion implantation (ion beam irradiation), baking, or the like can be performed. In addition, a thin film of an insolubilized film may be formed between the first resist pattern 51 and the second resist pattern 52, for example, on the upper surface and the side surface of the first resist pattern 51 to prevent mixing of both.

  After that, as shown in FIG. 5C, a contact fringe pattern is formed by the second resist pattern 52 so as to cover the end portion of the first resist pattern 51 and the poly-Si film 50 in the vicinity thereof from above. (Step S204).

  Then, the poly-Si film (film to be processed) 50 is etched using the first resist pattern 51 and the second resist pattern 52 as an etching mask (step S205). Finally, the first resist pattern 51 and the second resist are etched. The pattern 52 is peeled off (step S206).

  As a result, as shown in FIG. 5D, a fringed gate pattern 53 made of a poly-Si film could be formed. If an insolubilized film is formed between the first resist pattern 51 and the second resist pattern 52 and the insolubilized film formation is not selective, the insolubilized film is formed before the poly-Si film 50 is etched. The etching process is added. When forming an insolubilized film between the first resist pattern 51 and the second resist pattern 52, if an insolubilized film is formed only on the upper and side surfaces of the resist pattern, no additional etching process is required. In the peeling process, if the material can be peeled off together with the resist, the material is peeled off in step S206. However, if the material is not peeled off, an insolubilized film peeling process is required before step S206.

  In this embodiment, the resist insolubilization process is increased by using the resist pattern instead of the hard mask, but the hard mask film formation, processing, peeling process, and the first resist pattern peeling process can be omitted. The number and cost can be reduced. On the other hand, the contact fringe and the gate pattern can be formed in desired dimensions, and a pattern equivalent to the case where a hard mask is used can be formed.

  As described above, in the present embodiment, when a fine pattern formed by resist slimming and a narrow space pattern that cannot be formed by slimming coexist, two resist patterns are stacked instead of a hard mask. Form.

  First, after forming the first resist pattern, slimming is performed to form fine lines. Next, the first resist pattern is insolubilized to form a second resist pattern including a narrow space pattern. Thereafter, the film to be processed is etched using the first and second resist patterns as a mask to obtain a desired pattern.

  That is, the first and second resist patterns are patterned independently. For this reason, in the same layer, it is possible to allow a fine line pattern in which a necessary margin cannot be obtained unless it is formed by slimming and a narrow space pattern in which a necessary margin cannot be obtained by slimming with a sufficient margin.

  Furthermore, in the past, the fine resist pattern was formed and transferred to the hard mask. However, the pattern forming method of the present embodiment eliminates the need for a hard mask, thereby reducing the number of steps and cost.

(Second Embodiment)
A pattern forming method according to the second embodiment of the present invention will be described with reference to FIGS.

  The method of using a resist pattern instead of a hard mask is not limited to the case described in the first embodiment, and can be applied to other patterns. In the pattern forming method of this embodiment, for example, A pattern that cannot be formed by one exposure is formed by shifting the double period pattern by a period and forming it twice.

  That is, in order to form an L & S pattern having a fine pitch that cannot be formed once, a 1: 3 L & S resist pattern having a period twice the desired pitch is formed, and then the 1: 3 L & S resist pattern is shifted by the desired pitch. In this method, a double period pattern is finally formed.

  Compared to forming the 1: 3 L & S resist pattern from the beginning, the process window in the lithography process can be wider in the L & S pattern having a larger line width than in the 1: 3 L & S pattern. For this reason, the line width is first formed wider than the 1: 3 L & S pattern, and then ashing is performed to form the 1: 3 L & S pattern.

  Specifically, for example, in the case where a 32 nm 1: 1 L & S pattern is formed below, the first resist pattern is a 128 nm pitch L & S pattern. For example, the exposure margin when the illumination condition is quadrupole illumination with NA = 1.0, the opening angle is 35 degrees, the inner σ = 0.68, the outer σ = 0.85, and the azimuthal polarized light illumination. The results obtained by changing the line width are described below.

  Here, since the depth of focus can be set to 300 nm or more, the following discussion is based on the exposure amount margin. When a 1: 3 L & S pattern was formed from the beginning, when the dimensional tolerance was 10% of the desired dimension, that is, 3.2 nm, the exposure margin was 3.8%, but the exposure margin was As the line width increases, the exposure amount margin increases to 7.1% when a 1: 1 L & S pattern is formed. Therefore, in order to widen the margin in the litho stage, an L & S having a line width greater than 1: 3 is first formed, and then slimming is performed to form a 1: 3 L & S pattern.

  FIG. 7 shows a conventional process flow using a hard mask when forming the above-mentioned fine pitch L & S pattern. The process flow is basically the same as the conventional example of forming the gate and contact fringe described with reference to FIGS. 3 and 4 in the first embodiment.

  8A and 8B, the hard mask material 71 is formed in step S801 (FIG. 7A), the first resist pattern 72 is formed in step S802 (FIG. 7B), and the first resist is formed in step S803. The resist pattern 72 is slimmed (FIG. 7C), the hard mask material 71 is processed in step S804, the first resist pattern 72 is peeled off in step S805 (FIG. 7D), and the second resist pattern in step S806. 74 is formed (FIG. 7E), the second resist pattern 74 is slimmed in step S807 (FIG. 7F), and the processed film 70 is masked using the second resist pattern 74 and the hard mask 73 in step S808. Etching, peeling of the second resist pattern 74 in step S809, and hard mask 7 in step S810 Desired pattern 75 of the film to be processed by the peeling were obtained (FIG. 7 (g)).

  The difference from the gate and contact fringe formation described with reference to FIGS. 3 and 4 is that the second resist pattern 74 is a pattern in which the first resist pattern 72 (L & S pattern) is laterally shifted by 64 nm. Is mentioned. Further, the second resist pattern is also first formed as a line larger than 32 nm, and after that, slimming by ashing is performed to obtain a line of 32 nm.

  A process flow according to this embodiment using a resist pattern instead of a hard mask when forming the pattern will be described below with reference to a top view of FIG. 9 and a flowchart of FIG.

  In the present embodiment, both the first resist pattern and the second resist pattern form lines larger than 32 nm. However, since it is necessary to allow the second resist pattern to be a space portion, the line width of the first resist pattern 91 is set to 55 nm on the film to be processed 90 as shown in FIG. It forms (step S1001 of FIG. 10).

  When the dimension of the first resist pattern 91 is changed by the insolubilization process and the patterning of the second resist pattern, which are subsequent processes, the patterning is performed in consideration of the dimensional change amount of the first resist pattern 91 in step S1001. I do.

  Subsequently, insolubilization processing of the first resist pattern 91 is performed (step S1002), and as shown in FIG. 9B, a second resist pattern 92 is formed (step S1003). Thereafter, as shown in FIG. 9C, the first resist pattern 91 and the second resist pattern 92 are collectively slimmed by ashing (step S1004).

  Thereafter, the film 90 to be processed is etched using the first resist pattern 91 and the second resist pattern 92 as a mask (step S1005), and finally the first resist pattern 91 and the second resist pattern 92 are peeled ( Step S1006), a desired L & S pattern 93 of the film to be processed as shown in FIG. 9D is formed.

  In order to form such a fine pitch L & S pattern, conventionally, a hard mask is used, so that there is a problem that the number of steps is large and the cost is increased. However, although the resist insolubilization process is increased by using a resist instead of using a hard mask as in this embodiment, the hard mask film formation, processing, peeling process, and the first resist pattern peeling process can be omitted. The slimming process by ashing can be reduced by one process. Since the number of steps can be reduced in this way, the cost can be reduced.

  The process flow of this embodiment using a resist instead of using a hard mask can be performed in the same manner as in FIG. 6 of the first embodiment in which a gate and a contact fringe are formed. That is, the first resist pattern 91 can be slimmed between steps S1001 and S1002, the second resist pattern 92 can be formed with a desired dimension pattern from the beginning, and step S1004 can be executed in the omitted process order. It is.

  In this case, the process window in the lithography process of the first resist pattern 91 (L & S pattern) can be wider than in the case of FIG. 9, but the process window in the lithography process of the second resist pattern 92 (L & S pattern) is Narrow. Further, the number of times of slimming (ashing) is the same as in this embodiment. However, also in this case, the number of steps and cost can be reduced as compared with the conventional case.

(Third embodiment)
A pattern forming method according to the third embodiment of the present invention will be described with reference to FIGS.

  In the pattern forming method of this embodiment, a lower layer anti-reflection coating (BARC: Bottom Anti-Reflection Coating) is formed under the resist pattern. In this case, an example will be described in which the number of steps and cost are reduced by overlapping two resist patterns instead of a hard mask.

  FIG. 11 is a process sectional view of the pattern forming method according to the present embodiment, and FIG.

  First, as shown in FIG. 11A, a first antireflection film 111 (BARC) is applied on a film to be processed 110 such as poly-Si (polysilicon) (step of FIG. 12). S1201). As the lower antireflection film (BARC) used here, for example, ARC29a (manufactured by Nissan Chemical Industries), which is an organic BARC, is used with a film thickness of 85 nm.

  Next, as shown in FIG. 11B, a first resist pattern 112 is formed (step S1202).

  Further, the first resist pattern 112 is slimmed (step S1203), and as shown in FIG. 11C, the first antireflection film 111 is processed using the slimmed first resist pattern 112 as a mask (step S1203). S1204).

  Thereafter, the first resist pattern 112 is insolubilized by the method described in the first embodiment or the like (step S1205), and as shown in FIG. A film 113 (BARC) is applied (step S1206). In the resist insolubilization process, the first antireflection film 111 may also be insolubilized at the same time.

  Furthermore, as shown in FIG. 11E, a second resist pattern 114 is formed (step S1207). Then, as shown in FIG. 11F, the second antireflection film 113 is processed using the second resist pattern 114 as a mask (step S1208).

  Thereafter, the processing target film 110 is processed using the first resist pattern 112 or the first antireflection film 111 and the second resist pattern 114 or the second antireflection film 113 as a mask, as shown in FIG. Finally, the resist and the antireflection film are peeled off (step S1210).

  Thereby, a desired pattern of the film 110 to be processed, for example, a contact fringe or a gate pattern formed in the first embodiment can be obtained.

  In contrast, FIG. 13 shows a flowchart when a conventional hard mask is used.

  By forming the anti-reflection film (BARC), both of the anti-reflection film coating and anti-reflection film etching processes increase, and further, an anti-reflection film peeling process is required in addition to the resist removal. However, comparing the flowchart shown in FIG. 12 of this embodiment with FIG. 13, it can be seen that even in this case, the number of steps can be reduced by using two layers of resist patterns as compared with the case of using a hard mask. That is, it is possible to form a pattern equivalent to the case where a hard mask is used, and at the same time to reduce the number of processes and the cost.

  In the present embodiment, an antireflection film (BARC) is formed twice for the first resist pattern 112 and for the second resist pattern 114. Compared to the conventional case of using a hard mask, the number of steps is reduced by the pattern forming method of this embodiment in which two layers of resist are stacked, but the number of steps is still very large.

  One way to reduce this is to use a developer soluble BARC that is soluble in the developer. Specifically, it is possible to use developer-soluble BARC such as AZKrFE01 (manufactured by AZ), NCA800 (manufactured by Nissan Chemical), IMBARC10-7 (manufactured by Brewer Science).

  By using the developer-soluble BARC as the antireflection film in the above-described embodiment, at the time of resist development, the antireflection film in which the resist is soluble is dissolved in the developer, and the antireflection film in which the resist is insoluble is developed. It can be made insoluble in the liquid. As a result, when the resist pattern is formed, it is possible to leave the antireflection film only at a place where the resist pattern is present and to remove the other antireflection film. Therefore, the processing of the antireflection film in steps S1204 and S1208 in FIG. Etching) process can be reduced.

(Fourth embodiment)
A pattern forming method according to the fourth embodiment of the present invention will be described with reference to FIGS.

  In the pattern forming method of the present embodiment, in order to reduce the number of steps further than the pattern forming method according to the third embodiment, the lower antireflection film (BARC) used for forming the first resist pattern, It is also used as it is when forming the second resist pattern. If the change amount of the optical constant of the lower antireflection film in the resist insolubilization treatment is sufficiently small, the common lower antireflection film can be used for both the first and second resist patterns.

  FIG. 14 is a process sectional view of the pattern forming method according to the present embodiment, and FIG.

  First, as shown in FIG. 14A, a transmittance adjusting layer 141 made of 350 nm coating type carbon on a film to be processed 140 made of, for example, poly-Si (polysilicon) or the like, from a spin-on glass of 45 nm. The phase adjustment layers 142 are sequentially formed (step S1501 in FIG. 15).

  Using the lower antireflection film (BARC) composed of the transmittance adjustment layer 141 and the phase adjustment layer 142 as a common antireflection film, the first resist pattern 143 is formed (step S1502), slimming (step S1503), and resist insolubilization treatment ( In step S1504), a second resist pattern 144 is formed (step S1505), and a two-layer resist pattern is formed as shown in FIG. 14B. The resist insolubilization process is performed by the method described in the first embodiment, but the antireflection films 141 and 142 may be insolubilized at the same time.

  Then, using the first resist pattern 143 and the second resist pattern 144 as a mask, a spin-on glass (phase adjustment layer) 142, and using the spin-on glass 142 as a mask, a coating type carbon (transmittance adjustment layer) 141 and an antireflection film sequentially. Is processed (step S1506).

  Further, the film to be processed 140 (poly-Si) having a thickness of 150 nm is processed using the coating type carbon pattern 141 processed as described above as a mask (step S1507).

  Finally, the resist and the antireflection film are all removed (step S1508).

  As a result, a fringed line poly-Si pattern having the desired dimensions shown in FIG. 1 could be formed.

  With the above pattern forming method, the number of steps can be reduced as compared with the pattern forming method shown in FIG. 12 according to the third embodiment, and as a result, the cost can be reduced.

  In this embodiment, a two-layer antireflection film (BARC) composed of a transmittance adjustment layer and a phase adjustment layer is used. However, a single layer organic BARC is used for antireflection common to the first and second resist patterns. It can also be used as a membrane. In this case, it is normal that the first resist pattern 143 and the second resist pattern 144 still remain when the film to be processed 140 is processed. In step S1507, the first resist pattern 143 is left. The second resist pattern 144 and the antireflection film serve as a mask for the film to be processed.

  Regardless of whether it is a single layer or two layers, the antireflection film is used in common for the two resist patterns, thereby processing the first antireflection film after slimming (step S1203) in FIG. Since the etching process (step S1204) and the second antireflection film coating process (step S1206) are eliminated, the number of processes can be reduced.

  Further, by using the antireflection film in common, the effect of reducing the step is remarkable in the three-layer resist process in which the lower antireflection film (BARC) is composed of the phase adjustment layer and the transmittance adjustment layer. When the lower antireflection film is composed of a phase adjustment layer and a transmittance adjustment layer, it is originally desirable that both the phase adjustment layer and the transmittance adjustment layer are thin, but the transmittance adjustment layer serves as a mask when processing a film to be processed. When the selectivity ratio between the transmittance adjusting layer and the film to be processed is low, it is necessary to increase the thickness.

  Therefore, in the case of the third embodiment in which the antireflection film is provided for each resist pattern, as can be seen from FIG. 11F, the second resist pattern 114 is formed on the second antireflection film 113 having two layers. If formed, the step becomes particularly large.

  However, when a common antireflection film (BARC) is used for the first and second resist patterns as in this embodiment, the step due to BARC does not occur as shown in FIG. Does not require a large focus margin.

  In the embodiment described above, for example, poly-Si has been described as an example of a film to be processed which is a gate material. However, the material of the gate is not limited to poly-Si, and other materials are possible.

  In the above-described embodiment, it has been described that there is no processing conversion difference at the time of etching. However, it is needless to say that the finished dimension of the resist may be adjusted by taking the processing conversion difference into account.

  In the first, third, and fourth embodiments, the case where the line pattern and the contact fringe pattern are formed in the gate layer made of the film to be processed has been described as an example. However, the pattern is not limited to this.

  Lithographic patterning cannot provide a sufficient margin, and a fine pattern that must be formed by slimming, and a narrow space pattern that cannot be formed by slimming, or a pattern that does not allow the necessary margin when patterned in consideration of slimming In the case where coexists, the above embodiment can be applied.

  That is, first, in order to include a fine pattern that must be formed by slimming as the first resist pattern, patterning is performed in consideration of a narrow space pattern and slimming that cannot be formed by slimming as the second resist pattern. The pattern is distributed so as to include a pattern in which a necessary margin cannot be obtained.

  Next, the first pattern and the second pattern are formed separately, and only the first resist pattern is slimmed after the first resist pattern is formed. As a result, it is possible to select conditions that allow the maximum margin for each resist pattern, and both patterns can be formed with a sufficient margin. At the same time, the number of steps and cost can be reduced as compared with the conventional pattern forming method using a hard mask.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention in the implementation stage. The above-described embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and the effect described in the column of the effect of the invention Can be extracted as an invention. Furthermore, constituent elements over different embodiments may be appropriately combined.

The figure which shows the line pattern and contact fringe finally formed with the pattern formation method which concerns on embodiment of this invention. The figure which shows the pattern formed before slimming, when forming the pattern of FIG. 1 by slimming. The top view which shows the conventional pattern formation method using a hard mask. 4 is a flowchart showing a conventional pattern forming method shown in FIG. 3. 1 is a top view showing a pattern forming method according to a first embodiment of the present invention. 3 is a flowchart showing a pattern forming method according to the first embodiment of the present invention. The top view which shows the conventional pattern formation method using a hard mask. The flowchart which shows the conventional pattern formation method shown in FIG. The top view which shows the pattern formation method which concerns on the 2nd Embodiment of this invention. 9 is a flowchart showing a pattern forming method according to a second embodiment of the present invention. Sectional drawing which shows the pattern formation method which concerns on the 3rd Embodiment of this invention. 9 is a flowchart showing a pattern forming method according to a third embodiment of the present invention. The flowchart which shows the conventional pattern formation method. Sectional drawing which shows the pattern formation method which concerns on the 4th Embodiment of this invention. 9 is a flowchart showing a pattern forming method according to a fourth embodiment of the present invention.

Explanation of symbols

10 ... Line pattern, 11, 12 ... Contact fringe,
30, 50, 70, 90, 110, 140 ... film to be processed, 31, 71 ... hard mask material,
32, 51, 72, 91, 112, 143... First resist pattern,
33, 73 ... hard mask,
34, 52, 74, 92, 114, 144 ... second resist pattern,
35 ... desired pattern, 53 ... gate pattern with fringe, 93 ... L & S pattern,
111 ... 1st antireflection film, 113 ... 2nd antireflection film, 141 ... Transmittance adjustment layer,
142: Phase adjustment layer.

Claims (4)

Forming a first resist pattern on the film to be processed , including a pattern that cannot be obtained by lithography patterning unless it is formed by slimming ;
Slimming the first resist pattern;
A step of insolubilizing the first resist pattern so as not to dissolve after the slimming step;
A second pattern including a pattern that cannot be formed in consideration of slimming, or a pattern in which a necessary margin cannot be obtained when slimming is performed on at least one of the insolubilized first resist pattern and the film to be processed. Forming a resist pattern of
And a step of processing the film to be processed using the first resist pattern and the second resist pattern as a mask. Forming a first lower antireflection film on the film to be processed;
Forming a first resist pattern including a pattern on the first underlayer antireflection film including a pattern that cannot be obtained by lithography patterning unless it is formed by slimming ;
Slimming the first resist pattern;
Processing the first lower antireflection film using the slimmed first resist pattern as a mask;
Insolubilizing the slimmed first resist pattern so as not to dissolve;
Forming a second lower antireflection film on the first resist pattern and the film to be processed after the insolubilization;
Forming a second resist pattern on the second lower antireflection film , including a pattern that cannot be formed in consideration of slimming, and a pattern that cannot take a necessary margin when slimming is performed ;
Using the second resist pattern as a mask, processing the second lower antireflection film,
Processing the film to be processed using the first resist pattern or the first lower antireflection film and the second resist pattern or the processed second lower antireflection film as a mask. The pattern formation method characterized by the above-mentioned. Forming a lower antireflection film on the work film;
Forming a first resist pattern including a pattern on the lower antireflection film including a pattern that cannot be obtained by lithography patterning unless it is formed by slimming ;
Slimming the first resist pattern;
A step of insolubilizing the first resist pattern so as not to dissolve after the slimming step;
A pattern including a pattern that cannot be formed in consideration of slimming and a pattern in which a necessary margin cannot be obtained when slimming is performed on at least one of the lower antireflection film and the insolubilized first resist pattern. Forming a resist pattern of 2;
Processing the lower antireflection film using the first resist pattern and the second resist pattern as a mask;
And a step of processing the film to be processed using the first resist pattern, the second resist pattern, or the processed lower antireflection film as a mask. The pattern forming method according to claim 1, wherein the insolubilization process is performed by one of ion implantation and baking.

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