JP4025341B2 - Cleaning method of developer supply nozzle - Google Patents

Description

The present invention relates to a lithography process in the manufacture of semiconductor devices, electronic circuit components, liquid crystal display elements, and the like, and more particularly to a method for cleaning a developer supply nozzle for developing a photosensitive resist film.

  Along with the miniaturization of the dimensions of semiconductor elements, the conventional developing method does not sufficiently infiltrate the developer between the patterns, which causes a problem of local non-uniformity of pattern dimensions in the chip. Further, with the increase in the diameter of the substrate, the conventional development method causes a non-uniform pattern dimension within the substrate surface, which is a serious problem.

  Generally, in a semiconductor manufacturing process, an alkaline aqueous solution such as tetramethylammonium hydroxide (TMAH) is used as a developer for a photosensitive resist. Since the developer is an aqueous solution, the wettability is not sufficient with respect to the hydrophobic photosensitive resist surface. Therefore, when the reaction product resulting from the neutralization reaction is in the vicinity of the surface, the developer is difficult to diffuse between the reaction product and the photosensitive resist surface, and the alkali ion concentration is locally different, resulting in the development speed. Has been observed to vary from place to place.

  For example, if there is a pattern that is located in a wide dissolution area and a pattern that is located in an area where the surroundings are almost undissolved, the reaction that exists in the vicinity of the pattern is generated in the pattern that is located in the wide dissolution area. Since the amount of the product is large and the developer is difficult to diffuse between the reaction product and the photosensitive resist, the progress of the development is hindered, and the line size is thicker than the pattern arranged in the area where the periphery is hardly dissolved. There was a problem that it would become (a dimensional difference in the density pattern).

  As described above, there is a problem that a dimensional difference is generated according to the pattern density, and the in-plane uniformity of the resist pattern dimension is deteriorated.

An object of the present invention is to provide a developer supply nozzle cleaning method capable of improving in-plane uniformity of resist pattern dimensions.

  The present invention is configured as follows to achieve the above object.

The present invention relates to a method of cleaning a developer supply nozzle used when developing an exposed photosensitive resist film, and supplying an oxidizing liquid to a developer supply nozzle for supplying a developer onto a substrate to be processed. Wash.

  According to the present invention, between the start time and end time of the step of causing the developer to flow, the removal time for the developer to reach the bottom surface of the photosensitive resist film region is included, or the start of the step of causing the developer to flow By setting the time after the time for the developing solution to reach the bottom surface of the soluble region of the target pattern, the in-plane uniformity of the resist pattern dimension can be improved.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a flowchart of a processing procedure of a development processing method according to the first embodiment of the present invention. 2 to 6 are process diagrams showing a processing procedure of the development processing method according to the first embodiment of the present invention.

  A developing method according to the first embodiment of the present invention will be described with reference to FIGS.

(Step S101)
As shown in FIG. 2, a chemically amplified resist (photosensitive resist film) is formed on the main surface of the substrate to be processed 100 including a semiconductor substrate via an antireflection film, and the chemically amplified resist film Using a KrF excimer laser, a circuit pattern is subjected to reduced projection exposure via an exposure reticle. After performing the PEB process on the substrate to be processed 100, the substrate to be processed 100 is transferred to the upper part of the substrate holding unit 101 of the developing device by the transfer robot, and is sucked and fixed to the substrate holding unit 101. The substrate to be processed 100 is rotated by the rotating mechanism 102 as necessary, such as during rinsing and drying.

  The developing device according to the present embodiment further includes a rinse nozzle 103, a developer supply nozzle 104, and a scanning mechanism that scans the developer supply nozzle 104 from one end to the other end of the substrate 100. The rinse nozzle 103 discharges an oxidative liquid such as ultrapure water, ozone water, oxygen water, or a weak alkaline liquid from the discharge port when the substrate to be processed 100 is rinsed or when development is stopped. The developer supply nozzle 104 has a side longer than the longest diameter of the substrate 100 to be processed, and uniformly supplies the developer to the substrate 100. The rinsing nozzle prevents the cleaning liquid to be discharged in order to prevent damage to the photosensitive resist on the main surface of the substrate to be processed by the discharged oxidizing liquid or weak alkaline liquid and to make the operation of the cleaning liquid uniform on the substrate. It is desirable to have a mechanism for swinging and a mitigation mechanism for preventing the momentum of the cleaning liquid from locally increasing inside the nozzle discharge port.

(Step S102)
Next, as shown in FIG. 3A, the rinse nozzle 103 is moved from the substrate to be processed 100 to a predetermined height. While rotating the substrate 100 to be processed by the rotating mechanism 102, ozone water 106 having an ozone concentration of 5 ppm or less is discharged from the rinse nozzle 103 to the substrate 100 as a pretreatment liquid for about 2 seconds. In the meantime, the rinse nozzle 103 moves on the main surface of the substrate 100 to swing the ozone water 106 and supply it as uniformly as possible on the main surface of the substrate 100. Next, as shown in FIG. 3B, the substrate to be processed 100 is rotated to dry the surface of the substrate 100.

  Here, a pretreatment process is performed in order to uniformly form a liquid film on the substrate to be processed, but this pretreatment process is not necessarily required. In addition, oxygen water, hydrogen water, nitric acid, hydrogen peroxide, alkali ion water, or the like may be used as a pretreatment liquid as long as a liquid film can be formed more uniformly than ozone water.

(Step S103)
Next, as shown in FIGS. 4A and 4B, as a first development process, a film of a developer that processes the photosensitive resist film on the substrate 100 to be processed is formed on the substrate 100 to be processed. Here, the developer film 107 is formed on the substrate 100 by causing the linear developer discharge nozzle 104 to scan from one end of the substrate to be processed 100 to the other end and discharging the developer 107 in a curtain shape. As shown in FIG. 4B, the length of the developer supply nozzle 104 in the direction perpendicular to the scanning direction is longer than the diameter of the substrate to be processed 100, so that the film of the developer 107 is formed on the entire surface of the substrate to be processed 100. Can be formed.

  The developer film forming step is not limited to the method shown here. For example, as shown in FIGS. 5A and 5B, while supplying the developing solution from the linear developing solution supply nozzle 104, the substrate to be processed 100 is rotated and the developing solution film is formed on the entire surface of the processing substrate 100. There is a method of forming 107. FIG. 5 is a view showing a modified example of the developer film forming method according to the first embodiment of the present invention. FIG. 5A is a cross-sectional view, and FIG. 5B is a plan view.

  Further, as shown in FIGS. 6A and 6B, while the developing solution 107 is supplied from the straight tubular nozzle 112 to the substrate to be processed 100, the substrate to be processed 100 is rotated to develop the entire surface of the substrate 100. There is a method of forming the liquid film 107. Other than the method shown here, various forms can be taken. FIG. 6 is a view showing a modified example of the developer film forming method according to the first embodiment of the present invention. 6A is a cross-sectional view, and FIG. 6B is a plan view.

(Step S104)
As the first cleaning process, about 5 seconds after the developer film is formed on the main surface of the substrate to be processed, pure water is discharged from the rinse nozzle 103 and simultaneously the substrate is rotated, so that the developer on the substrate 100 to be processed Rinse the membrane. Subsequently, low-concentration ozone water was discharged while rotating the substrate 100 at a low speed.

(Step S105)
Next, the substrate 100 to be processed was rotated at a high speed to dry the surface of the substrate 100.

  The substrate may be rotated at the same time as the low-concentration ozone water is discharged from the rinse nozzle 103, and after cleaning with the low-concentration ozone water for about 10 seconds, the substrate to be processed may be rotated at a high speed to dry the substrate.

  In this embodiment, low-concentration ozone water that does not damage the resist beyond an allowable range is used as the cleaning liquid having oxidizing properties. If there is a similar effect, oxygen water or the like in which oxygen is dissolved in pure water may be used as the oxidizing cleaning solution. Further, a weak alkaline aqueous solution may be used as long as the same effect is obtained and the resist is not damaged more than an allowable value.

(Step S106)
Next, as a second development process, a developing solution for processing the resist film on the target substrate 100 is formed on the target substrate 100. Here, the developer film on the substrate was formed by scanning the linear developer discharge nozzle from one end of the substrate to the other end and discharging the developer in a curtain shape.

  If necessary, the developer may be stirred on the main surface of the substrate to be processed during the second development process. In that case, for example, a method of stirring the formed developer film may be a method of arranging a rectifying plate on a substrate to be processed and rotating the rectifying plate to generate an air current, a method of rotating the substrate itself, Any method may be used as long as it has an effect of causing the developer to flow over the entire surface of the substrate, such as a method of applying vibration to the liquid by an external vibrator.

(Step S107)
As a second cleaning process, about 25 seconds after the developer film was formed on the main surface of the substrate 100 to be processed, pure water was discharged from the rinse nozzle 103 and the substrate 100 was rotated at 500 rpm. In this embodiment, pure water is used as the cleaning liquid after the second development. However, if there is a higher cleaning effect, a reducing liquid, an oxidizing liquid (ozone water, oxygen water), Any of alkaline ionized water, weakly acidic ionized water, supercritical water, carbonated water, hydrogen water, pure water, etc. may be used. In addition, these liquids can be appropriately combined as long as the cleaning effect is enhanced.

(Steps S108 and S109)
After the substrate to be processed is rotated at a high speed and the substrate is dried, the developing process is completed, and the substrate is collected by the transfer robot.

  Problems and causes of the conventional developing method will be described. In a chemically amplified photosensitive resist, a fine alkali-soluble region and a hardly alkali-soluble region are formed in a resist film by exposure and heat treatment of a desired pattern. When these alkali-soluble regions and alkali-poorly soluble regions come into contact with an alkali developer, the alkali-soluble region is dissolved in alkali and the alkali-poorly soluble region is dissolved in the time required for a general development process of a normal KrF resist. do not do. The reaction product generated from the alkali-soluble region during development is sandwiched between resist patterns that are hardly alkali-soluble regions, and is subjected to intermolecular interactions from the resist-soluble region and similarly dissolved reaction products. , Stay there. In particular, when the processing dimensions become finer, the resist pattern dimensions also become finer. Therefore, the alkali-soluble area and the dimension of the alkali-soluble area become smaller, and the interaction between molecules becomes stronger. It becomes difficult to diffuse into the atmosphere in the liquid. . In addition, a binding force acts on the reaction product so that the reaction product stays in place after dissolution due to the electrostatic potential from the substrate. As a result, the alkali ions are further prevented from diffusing into the soluble resist region, and the alkali concentration varies from place to place near the resist surface, development is inhibited, and the development speed varies from place to place.

  The developer was put on and stopped on the substrate to be processed, and immediately after a predetermined time elapsed, the developer on the substrate to be processed was replaced with a cleaning solution (pure water) to stop development. In this method, the local stagnation of the reaction product as described above occurs in the surface of the substrate and is not removed until the development is completed. Therefore, the development is hindered, and the development speed is different in the surface. In particular, since the developing speed varies depending on the amount of the reaction product, the amount of the reaction product generated differs between the sparse area and the dense area. For this reason, a phenomenon occurs in which the alkali ion concentration is different between the sparse pattern region and the dense region near the resist surface, that is, a development rate is different between the sparse pattern region and the dense resist surface. As a result, a problem of dimensional density difference occurs in the resist pattern.

  In order to solve the above problem, it was considered that the reaction product was once removed during development and development was performed again with a fresh developer. However, the method of performing development in two steps is a well-known technique, and is disclosed in, for example, Japanese Patent Application Laid-Open No. 2-46464. In Japanese Patent Application Laid-Open No. 2-46464, development is performed once with a developer, rinsed and dried, and then again developed with a developer having a high concentration. The inventor has said that the resist residue and scum at the bottom of the resist pattern are thereby removed. These residues and scum are undissolved portions of the resist, and are not reaction products generated by development that is to be removed by washing after the first development. Residues and scum on the bottom surface of the resist are singular points that may become defects after development, and do not substantially contribute to in-plane uniformity. Therefore, the above-mentioned Japanese Patent Application Laid-Open No. 2-46464 does not solve the problems in conventional development. Moreover, although there is no description in particular, the rinsing liquid in this case usually indicates pure water. This is a significant difference from the method shown in this embodiment.

  In general, after the first development, when the first cleaning process is performed with pure water, the developer having a high pH is replaced with pure water having a pH of 7, and a rapid pH change occurs on the resist surface, resulting in poor alkali solubility. A layer is formed. For this reason, in the second development of the pattern in which the reaction product has been removed cleanly, dissolution by alkali starts uniformly from this hardly soluble layer, and finally formed when this first development is replaced with washing. Remains reflecting the surface shape of the slightly soluble layer. On the other hand, the poorly soluble layer formed when the developing solution is replaced with the cleaning solution strongly reflects the influence of exposure amount variation, focus variation, development speed variation at the initial stage of development, and the uniformity is generally poor. . Therefore, the dimensional uniformity in the substrate surface of the resist pattern formed after development is worse than the normal one-time development. Therefore, it can be seen that the method disclosed in Japanese Patent Laid-Open No. 2-46464 not only solves the problems caused by the conventional developing method but also deteriorates the dimensional uniformity in the substrate surface.

  The developing method shown in this embodiment is characterized in that processing is performed with an oxidizing liquid such as ozone water between the first developing process and the second developing process. In the case of first cleaning with pure water and then subsequent cleaning with ozone water, the surface insolubilized layer formed by touching the pure water from the developer is treated with ozone water to modify the surface by oxidizing it. Quality. Or by slightly increasing the ozone concentration and slightly decomposing the surface, the surface hardly soluble is made soluble in alkali. On the other hand, when cleaning with ozone water from the beginning, ozone molecules easily enter and oxidize the resist surface swollen with the developer, so even if the pH is lowered, the resist surface is hardly insolubilized. It remains soluble in In either case, when the second development is continued, development is performed faithfully to the optical profile at the time of exposure and a resist pattern is formed regardless of the first development. Furthermore, if the development time is as long as that of the conventional development, the reaction product and the surface hardly-solubilized layer are not affected, and the development proceeds sufficiently, so that the exposure amount during exposure, focus variation, etc. The influence is alleviated and the in-plane dimensional uniformity of the resist pattern after development is improved. Further, by washing with an oxidizing liquid such as ozone water, the reaction product existing between the unformed resist patterns can be decomposed and removed cleanly. Furthermore, particles that can become defects after development can be removed.

  In addition, the time for discharging the first cleaning liquid from the first development is set to about 5 seconds in this embodiment, and this is due to the following reason. FIG. 7 schematically shows a graph of reflected light intensity with respect to time, which is obtained when the state of dissolution of the KrF positive resist film by the developer is observed. The sine wave seen in the first stage in the graph of FIG. 7 is an interference effect due to the film thickness that occurs because the development proceeds in the depth direction of the film thickness. In general, in this first stage immediately after the start of development, the resist has a high dissolution rate in the soluble region of the exposed portion 131 of the resist film 130, and the dissolution proceeds in the depth direction, as shown in FIG. It takes about 5 to 10 seconds for the positive resist for DUV exposure until it reaches the bottom of the film. In the second stage, as shown in FIG. 8B, the development proceeds not in the depth direction of the resist film thickness but in the direction of dissolving the resist pattern side wall. The reflection intensity at this time changes gently. In this second stage, the dissolution rate is reduced, and the side walls of the resist pattern are dissolved to a desired size, so that the dissolution direction proceeds in a relatively horizontal direction.

  In this way, the dissolution of the resist proceeds in the depth direction in the first stage, and proceeds in the lateral direction in the second stage because the exposure intensity distribution due to the diffraction of light unavoidable in the projection type exposure extends from the exposed part to the non-exposed part. This is because the exposure intensity changes gradually. Due to the distribution of the exposure intensity, a pattern having a large exposure amount, that is, a well-exposed pattern, and the middle part of the pattern are removed most rapidly during development, so that development is performed as in the first stage that proceeds rapidly in the depth direction. . On the other hand, in the vicinity of the pattern wall where the exposure amount is small, the development speed is slower than that in the intermediate portion, so the development is as shown in the second stage, which proceeds gently in the lateral direction. In this first stage, most of the soluble organisms that inhibit development in normal development are generated.

  In the present embodiment, the time for discharging the first cleaning liquid from the first development is about 5 seconds after the start of development, but this is where the first stage is switched to the second stage, that is, the development is reversed at the dissolving portion. This is where it proceeds in the direction to the bottom of the resist. The reason for this timing is as follows.

  The dissolution product once generated in the first stage is washed away when changing from the first stage to the second stage, thereby preventing a decrease in alkali concentration due to the dissolution product that inhibits the progress of development. If the first development is stopped earlier than this, a dissolved product is generated again at the next development stage, lowering the alkali concentration and inhibiting the development. If the first development stop time is made shorter than this, the local alkali concentration is lowered by the generated dissolved product, and the local development speed is lowered in the development in the second stage. Even if development is performed again with a fresh developer after this, the initially formed spatial non-uniformity cannot be resolved. As the first development stop time is delayed from the time when the first stage changes from the first stage to the second stage, the local decrease in alkali concentration at each location increases and the non-uniformity is also amplified.

  The solubilized area remaining in the vicinity of the pattern side wall, which is dissolved in the second stage, has a low dissolution rate during development. After washing once in the first stage, the alkali concentration related to development is varied temporally and spatially. Since the dissolved product which can be dissolved is already removed and hardly generated, the pattern line width can be sufficiently controlled in the second development. For the above two reasons, it is optimal to set the first development stop timing as a turning point between the first stage and the second stage.

  In the present embodiment, the point of switching from the first stage to the second stage in FIG. 7 was 5 seconds. This value varies depending on the resist material, developer, alkali concentration, temperature, and the like, and is not limited to the value of this embodiment.

Next, the effect of this embodiment will be described based on the results of experiments conducted by actual inventors. An antireflection film and a KrF positive resist are sequentially applied on the wafer, and are composed of a 200 nm line and space pattern (200 nm L / S pattern; L: S = 1: 1), a 200 nm line and a 2000 nm width space. Reduced projection exposure was performed with a KrF excimer laser using a reticle including a pattern (200 nm isolated line; L: S = 1: 10), and development processing was performed after the heat treatment step. In the development process, four types of samples were prepared as follows. The conditions are shown in (Table 1).

  All sample wafers are pre-treated with ozone water, the developer supply amount from the developer supply nozzle is 1.5 L / min, the nozzle scanning speed is 60 mm / sec, and a developer film having a liquid thickness of 1.5 mm Was formed (first development processing). The reference sample was not subjected to the first cleaning process and the second development process, and the developer film was formed once. Sample A was washed once with water (first washing process) 5 seconds after the start of development, and again the developer supply amount from the developer supply nozzle was 1.5 L / min, and the nozzle scanning speed was 60 mm / sec. As a result, a liquid film having a liquid thickness of 1.5 mm was formed (second cleaning process).

  On the other hand, in the sample B, the first cleaning process is performed with ozone water, and in the sample C, the first cleaning process is performed with pure water, followed by the subsequent cleaning with ozone water, and then the same as the sample A. A second developer film was formed (second development process). The subsequent second cleaning process and drying process were all performed under the same conditions.

The dimensional evaluation results of these samples are shown in (Table 2).

  In Table 2, the dimensional difference between the 200 nm L / S pattern and the 200 nm isolated line pattern on the same substrate is the density difference. The density difference in Table 2 was a value obtained by subtracting the size of the L / S pattern (1: 1 pattern) from the isolated line pattern (1:10 pattern).

  In the reference sample, the in-plane uniformity of the pattern dimensions is relatively good, but the reaction product generated by the development hardly moves after forming the developer film, so that the isolated line pattern with a large reaction area per unit area ( 1:10 pattern), the reaction region per unit area is 30 nm thicker than the size of the small L / S pattern (1: 1 pattern).

  On the other hand, in sample A, the density difference is slightly eliminated. On the other hand, the in-plane uniformity is greatly deteriorated. The following can be considered as these causes. First, the reason why the density difference is small is considered as follows. Usually, the amount of reaction products present in the vicinity of the pattern is locally different between a sparse part and a dense part of the resist pattern, so that a local difference also occurs in the alkali ion concentration in the developer. However, since the developer is once replaced with pure water and fresh developer is supplied again, this local difference in alkali concentration is eliminated. Therefore, regardless of the density of the pattern, development is promoted by a fresh developer, and development is performed faithfully to the original optical profile. Therefore, the dimensional difference caused by the density of the pattern is slightly reduced.

  The problem of in-plane dimensional uniformity can be considered for: In general, the dissolution rate is fast when the development time is early. In the early stage of the development time, for example, when the exposure amount or the exposure focus differs depending on the location on the wafer, the difference in dissolution rate appears more conspicuously. Usually, the development is performed for a sufficiently long time, and such a phenomenon is not observed. However, the first rinse of the present embodiment is discharged at an early stage of the development time, and the first development is stopped. . Therefore, it is considered that the above effect appears remarkably. At this time, by applying pure water while the development reaction is actively taking place, a sudden pH value change occurs, and the resist components aggregate at the interface between the resist and pure water, and are inherently dissolved. The resist surface of an undissolved part such as a pattern side wall such as a pattern side wall is hardly soluble. After that, development is performed again by adding the developer, but the surface of the resist in the region where dissolution is originally proceeded is agglomerated by contact with pure water, and the solubility is lowered. Instead, the dissolution proceeds reflecting the shape of the poorly soluble layer formed by touching pure water. Therefore, development proceeds while maintaining poor uniformity when cleaning is performed in a short time. As described above, the density difference is reduced by eliminating the influence of development inhibition caused by the reaction product due to development, but factors that have a large influence on the initial stage of development, such as exposure amount and focus blurring, have a large influence instead. , Which deteriorates the in-plane uniformity.

  On the other hand, it can be seen that in the sample B and the sample C, the uniformity in the wafer surface is equal to or higher than that of the reference sample. This is because once the resist is contacted with pure water, the resist agglomerates and a poorly soluble layer is formed on the surface. This is because it is oxidized to maintain the solubility in the developer. Therefore, when a developer having a fresh concentration is added again, the development is not hindered by the resist surface poorly-solubilized layer on the side wall of the pattern, and the development is continuously promoted and the in-plane dimensional uniformity is improved. .

  The effect of washing away the reaction product near the resist pattern by rinsing is the same as that of the sample A. When fresh developer is supplied for the second time, there is no local decrease in alkali concentration of developer due to the reaction product, and it is uniform, so that the dimensional density difference can be greatly reduced.

  Here, the sample B and the sample C are slightly different in homogeneity because the first cleaning process in the sample B is all washed with ozone water, so that a sudden pH value change occurs when the developer is changed to the rinse liquid. This is because the agglomeration of the resist component in the film is alleviated by ozone water and the ease of conformation of the resist surface to the developer is kept unchanged.

(Second Embodiment)
FIG. 9 is a flowchart of the development processing procedure according to the second embodiment of the present invention. Steps S201 to S203 are the same as steps S101 to S103 described in the first embodiment, and a description thereof will be omitted. (Steps S204, S205) About 5 seconds after the developer film was formed on the main surface of the substrate to be processed in Step S203, low-concentration ozone water was discharged from the rinse nozzle. Next, the substrate to be treated was rotated to remove most of the cleaning solution, but the substrate was not dried and the cleaning solution was left slightly to form an ozone water film.

(Step S206)
Next, a developer for processing the resist film on the substrate to be processed was formed on the substrate to be processed in a state where the ozone water film was formed. The method for forming the developer film is the same as in the first embodiment.

  Steps S207 to S209 are the same as steps S107 to S109 described in the first embodiment, and a description thereof will be omitted.

  The developing process of this embodiment has substantially the same operation as that of the first embodiment. In the present embodiment, when the developer is supplied by increasing the affinity of the developer with respect to the surface of the substrate to be processed during the second development process by leaving the oxidizing liquid or the weak alkaline liquid on the substrate main surface. The repulsive force acting between the developer and the substrate surface can be reduced, and the developer can be supplied uniformly within the surface of the substrate to be processed. As a result, the in-plane uniformity of the dimensions after development is improved. .

  From the first cleaning process to the second development process in the development process, after the first cleaning process, without rotating the substrate to be processed at high speed, the substrate was rotated at 500 rpm for 10 seconds, and then the second developer was discharged. . Except for the above points, the experiment was performed under the same conditions as those of the sample C of the first embodiment. As a result, the 1: 1 pattern uniformity 3σ was 6.1 nm, the 1:10 pattern uniformity 3σ was 7.5 nm, and the density difference was 5 nm. It is a sufficiently good value compared to the reference sample.

(Third embodiment)
In this embodiment, the procedure of the developing process is the same as that of the first embodiment, and thus detailed description thereof is omitted. In the present embodiment, gas molecules having oxidizing properties such as oxygen or gas molecules having reducing properties such as hydrogen are dissolved in the developer during the first and second development processing.

  The processing apparatus used in this embodiment is shown in FIG. As shown in FIG. 10, the apparatus includes a developer tank 201 in which a developer that is an alkaline aqueous solution is stored, a dissolved film 202 connected to the developer tank 201 via a pipe, and a pipe connected to the dissolved film 202. An oxidizing gas generator 203 and a reducing gas generator 204 connected to each other, and a developer supply nozzle 104 connected to the dissolution film 202 via a pipe. A protective cover is installed around the substrate 100. The same parts as those of the developing device shown in FIG.

  In this apparatus, the gas generated by the oxidizing gas generator 203 or the reducing gas generator 204 is dissolved in the dissolved film 202, and the developer supplied from the developer tank 201 is allowed to pass through the dissolved film 202. The oxidizing gas or reducing gas is dissolved in the developer. This apparatus can dissolve an oxidizing gas (reducing gas) in the developing solution immediately before the developing solution is discharged onto the substrate 100 to be processed.

  In the present embodiment, the first and second development processes are performed by dissolving oxygen gas in the developer as the oxidizing gas. Since other processes are the same as those in the first embodiment, a detailed description thereof will be omitted.

  In the first and second development processes, the developer in which oxygen molecules are dissolved is used. However, a developer in which reducing gas molecules such as hydrogen molecules are dissolved may be used. If the effect is sufficient, it is not necessary to use a developer in which oxidizing gas molecules are dissolved during both the first and second development processes, and either one of them may be used.

  In the present embodiment, in addition to the action described in the first embodiment, by using a solution in which oxidizing gas molecules are dissolved as a developer, oxygen in the developer of the reaction product generated immediately after the start of development is used. There are actions such as oxidation by molecules and decomposition of reaction products thereby, oxidation of the resist surface in the developer, and relaxation of size growth due to aggregation of reaction products generated during development.

  Further, when a developing solution in which reducing gas molecules are dissolved is used at the time of the first and second developing processes or one of the processes, the resist surface is modified by reducing electrons, and the surface potential of the reaction product is changed. There are effects such as promotion of diffusion of the reaction product into the developer and prevention of redeposition of the reaction product on the resist surface due to a change in the resist surface potential.

  An experiment similar to that of the first embodiment was performed using a developing solution in which oxidizing gas molecules were dissolved during the first and second developing processes. As a result of the experiment, the 1: 1 pattern dimension uniformity was 3.8 nm for 3σ and 6.1 nm for 1:10 pattern, confirming the expected effect.

(Fourth embodiment)
FIG. 11 is a diagram showing a flowchart of development processing according to the fourth embodiment of the present invention. Since the procedure in the pattern processing method of this embodiment is the same as that of the first embodiment, the illustration of the flowchart and the detailed description of the procedure are omitted.

  In the present embodiment, during the first development process, after the developer film is formed, development is performed with the substrate stationary. Then, after a predetermined time has elapsed, as shown in FIG. 12, the substrate is rotated at a predetermined rotational speed to cause the developer to flow. After the substrate is rotated for a predetermined time to cause the developer to flow, the substrate is rested again, and exposure is performed in a stationary state.

  In this embodiment, the time zone during which the developer flows is determined as follows. As described in the first embodiment, development is performed from the first stage in which development proceeds in the depth direction of the film thickness and the second stage in which development proceeds in the direction of dissolving the resist pattern sidewall after the first stage. Become.

  The purpose of liquid flow in the development process is to homogenize the reaction product generated during development and to recover the alkali concentration. Therefore, in order to perform the liquid flow effectively, the time for changing from the first stage in which a large amount of reaction products are generated to the second stage in which almost no reaction products are generated (hereinafter, this time is referred to as missing time). ) Should be included.

  Next, how to determine the missing time will be described. As a first method, there is a method in which a time change of reflected light intensity obtained by making light incident on a target pattern and reflected is measured to obtain a result as shown in FIG. At this time, since the reflected light intensity in FIG. 8 is preferably a reflected light having a single wavelength, the incident light is made to have a single wavelength by using a narrow band filter or the measured reflected light is dispersed. Better. The missing time may be measured in advance before actual development, or may be measured for each substrate in the development process.

  As a second method, a target pattern is developed in a plurality of development times, a cross-sectional shape of the pattern after development is observed, and the time required for developing the resist in the soluble region to the bottom surface is obtained. is there. Next, the measurement of the missing time will be described based on two experimental results. The target pattern of the first experiment was a 130 nm L / S (1: 1) pattern (an antireflection film having a thickness of 60 nm, a resist having a thickness of 300 nm, and a resist having a relatively high dissolution rate). First, the reflected light intensity during development of the target pattern shown in FIG. 13 was acquired. The reflection intensity is the result when light having a wavelength of 550 nm is incident. From this result, the removal time was determined to be 6 seconds, and the liquid flow time was determined based on this value.

  FIG. 14 shows a time axis representing the flow of development start, developer flow, and development end. After the developer supplying step, static development is performed for (x-1) seconds. Thereafter, the substrate was rotated at a predetermined rotation speed (250 rpm) for 2 seconds to flow the developer. The development was stopped 30 seconds after the start of development. X at this time was defined as the timing of liquid flow. FIG. 15 shows the variation (3σ) of the 130 nm L / S (1: 1) pattern when x is changed in 2 to 12 seconds. The variation in the case of no liquid flow was 10.2 nm, and the variation was reduced by performing the liquid flow. In particular, the best uniformity was obtained at 6 seconds. Also, the uniformity was relatively good in the case of 4 seconds and 8 seconds. That is, good uniformity is obtained when the liquid flow is performed in the vicinity of the omission time obtained from the reflected light intensity change of the target pattern (the omission time ± 2 seconds, that is, the omission time ± 33%).

  Experiments have shown that the uniformity of the liquid flow can be improved by setting the liquid flow timing close to the exit time (the time when the resist in the soluble region is developed to the bottom surface). When the liquid flow start time can only be set after the exit time due to the restrictions of the apparatus (for example, in this experiment, when the substrate can be rotated only after 9 seconds), the time is as early as possible (for example, 9 seconds). Good to do.

  The target pattern of the second experiment was a 130 nm L / S (1: 1) pattern (an antireflection film with a thickness of 60 nm, a resist with a thickness of 300 nm, a resist with a relatively low dissolution rate). First, the reflected light intensity during development of the target pattern shown in FIG. 16 was acquired. This is a result when light having a wavelength of 550 nm is incident. From this result, the removal time was determined to be 20 seconds, and the liquid flow time was determined based on this value.

  A diagram showing the sequence on the time axis is shown in FIG. After the developer supply step, static development was performed for (x-1) seconds. Thereafter, the substrate was rotated at a predetermined rotation speed (250 rpm) for 2 seconds to flow the developer. The development was stopped 60 seconds after the start of development. X at this time was defined as the timing of liquid flow. FIG. 17 shows 130 nm L / S (1: 1) pattern variation (3σ) when x is changed in 10 to 35 seconds. The variation in the case of no liquid flow was 9.8 nm, and the variation was reduced by performing the liquid flow. In particular, the best uniformity was obtained at 20 seconds. Also, the uniformity was relatively good at 15 seconds and 25 seconds. That is, good uniformity is obtained when liquid flow is performed in the vicinity of the omission time obtained from the reflected light intensity change of the target pattern (omission time ± 5 seconds, ie, omission time ± 25%).

  In the present embodiment, the method of rotating the substrate is shown as the method of liquid flow, but the method of flowing the developer by forming an air flow on the surface of the developer film, and the object that causes the flow to be processed substrate A method of flowing the developer by moving the object or the substrate in contact with the developer above, a method of causing the developer to flow by vibrating the substrate to which the developer is supplied, heating the treatment, Any method of flowing the developer such as a method of flowing the developer by convection may be used.

  In the present embodiment, the L / S pattern is the target pattern, but any pattern such as an isolated remaining pattern, an isolated pattern, a hole pattern, a pillar pattern, or the like may be used. It is only necessary to determine the liquid flow timing by obtaining the pattern removal time. When a plurality of patterns (for example, an isolated remaining pattern and an L / S pattern) are included at the same time, the liquid flow may be performed twice from the respective removal times, or the liquid flow from the removal time of only the pattern with strict accuracy. You may decide the timing.

  Many proposals have been made to cause the developer to flow. For example, after supplying the developer onto the substrate, an air flow is formed so as to come into contact with the surface of the developer film, thereby forming a surface flow while holding the developer film on the substrate and causing the developer to flow. A method of causing the developer to flow by bringing the tip of a nozzle for supplying the developer into contact with the developer on the substrate to be processed and moving the nozzle or the substrate (JP 20002000). No. 195773), and a method of causing the developing solution to flow by applying vibrations of a predetermined frequency to the substrate to which the developing solution is supplied (Japanese Patent Laid-Open No. 2001-307994) has been reported. However, none of the proposals describes at what timing the liquid flow should be performed after supplying the developer. As a result, since liquid flow was not performed in an appropriate time zone, effective liquid flow was not possible, and sufficient dimensional uniformity could not be obtained.

(Fifth embodiment)
In the semiconductor manufacturing process, a process of forming a developer paddle on a substrate to be processed on which a resist film is formed and processing the resist film into a desired shape is repeatedly performed. Conventionally, a developing solution is applied on a substrate on which a resist film is formed, and a developing process is performed. In general, a developer supply nozzle is used to supply the developer. As described above, in the developing method using the developing solution supply nozzle, the tip of the nozzle from which the developing solution is discharged is positioned close to the substrate to be processed, and the solution is supplied. Therefore, the developing solution in which the resist is dissolved comes into contact with the nozzle. As a result, the resist solid matter adheres to the developer supply nozzle. In some cases, the deposits may cause defects in the substrate to be processed.

  As means for solving this problem, nozzle cleaning with a developer and nozzle cleaning with a high-concentration developer (Japanese Patent Laid-Open No. 2001-319869) are performed. In these methods, since the developer is used as the cleaning solution, only defects that are soluble in the developer can be removed. Further, since the developer is used, there is a problem that the cost is increased.

  FIG. 18 is a flowchart showing a processing procedure of a pattern method according to the fifth embodiment of the present invention. FIG. 19 is a schematic diagram of the configuration of the developing device according to the first embodiment of the present invention. A development processing method according to the first embodiment of the present invention will be described with reference to FIGS.

(Step S401)
An antireflection film and a chemically amplified resist are coated on the substrate to be processed, and a desired pattern is reduced projection exposed through an exposure reticle using a KrF excimer laser. The substrate is heat-treated, transferred to the upper part of the substrate holding unit by a transfer robot, and sucked and fixed to the substrate holding unit.

(Step S402)
Next, ozone generated by the oxidizing gas generator 304 is supplied to the dissolving film 303, and pure water is supplied from the pure water source 302 to the dissolving film 303, whereby ozone is dissolved in pure water to generate ozone. . Then, the generated ozone is supplied to the developer supply nozzle 104. When the developer supply nozzle 104 discharges ozone water, the developer supply nozzle 104 is washed. The ozone water discharged from the developer supply nozzle 104 is received by the liquid receiver 305, and the ozone water is stored in the liquid receiver 305. The surface of the developer supply nozzle 104 facing the resist film is cleaned by immersing the developer supply nozzle 104 in the ozone water stored in the liquid receiving portion 305.

  After cleaning the developer supply nozzle 104, the developer is supplied from the developer tank 301 to the developer supply nozzle 104, and the developer is discharged from the developer supply nozzle 104, whereby the ozone water in the nozzle is replaced with the developer. To do.

  Note that the oxidizing gas generator 304 is not necessary when the oxidizing gas can be supplied to the line. In addition to ozone, oxygen, carbon monoxide, and hydrogen peroxide may be used as the oxidizing gas.

(Step S403)
Next, a developer film for processing the resist film on the substrate to be processed is formed on the substrate to be processed. Here, a developer film is formed on the substrate to be processed by scanning from one end of the wafer to the other while supplying the developer using a linear developer supply nozzle.

(Step S404)
After a predetermined time, a rinsing liquid (for example, pure water) is supplied from a rinsing nozzle disposed above the substrate to be processed, and the substrate is cleaned while rotating.

(Step S405)
Furthermore, pure water is sprinkled off by rotating the substrate to be processed at a high speed, and the substrate to be processed is dried.

  In this embodiment, ozone water in which ozone is dissolved in pure water is used as the oxidizing liquid. However, gas molecules to be dissolved are not limited to ozone if there is a similar effect. For example, an oxidizing gas such as oxygen, carbon monoxide, or hydrogen peroxide may be used. In this embodiment, the nozzle cleaning is performed before supplying the developer, but it may be performed after supplying the developer. Further, the cleaning may not be performed for each substrate, but may be performed for every predetermined number of sheets and every predetermined time. Moreover, you may perform after maintenance, such as replacement | exchange of a nozzle.

  As the development process is repeated, the developer supply nozzle comes into contact with the developer in which the resist is dissolved, so that organic particles adhere to the nozzle. In the subsequent development processing of the substrate, the particles may adhere to the resist surface and remain as defects.

  It is considered that ozone molecules in the liquid collide with particles adhering to the nozzle during cleaning and oxidize and decompose the particles with a certain probability. The decomposed particles become low molecules, and the mass thereof becomes sufficiently small, so that diffusion into the liquid becomes easy. As a result, particles are removed.

  The results of experiments actually conducted by the inventors will be described below. The experiment was performed according to the procedure shown in the flowchart of FIG. In order to confirm the effect, in step S402, when the nozzle was washed with ozone water having an ozone concentration of 10 ppm in the solution for 5 seconds, washed with the developer for 5 seconds, and the number of organic matter adhesion defects was measured when not washed. . The number of defects was 5, 10, 50, respectively, and the number of defects was reduced by cleaning with ozone water. From these results, it was confirmed that cleaning of the developer supply nozzle 104 with ozone water is very effective.

  In addition, this invention is not limited to the said embodiment, In the implementation stage, it can change variously in the range which does not deviate from the summary. Further, the above 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 obtained as an invention.

FIG. 5 is a flowchart illustrating a processing procedure of the development processing method according to the first embodiment. FIG. 3 is a process diagram illustrating a development processing method according to the first embodiment. FIG. 3 is a process diagram illustrating a development processing method according to the first embodiment. FIG. 3 is a process diagram illustrating a development processing method according to the first embodiment. FIG. 3 is a process diagram illustrating a development processing method according to the first embodiment. FIG. 3 is a process diagram illustrating a development processing method according to the first embodiment. The figure which shows typically the graph of the reflected light intensity from the general board | substrate obtained when the mode of melt | dissolution with the developing solution of a KrF positive type resist is observed. Sectional drawing which shows typically the resist film under development. The figure which shows the flowchart of the image development processing procedure concerning 2nd Embodiment. FIG. 10 is a diagram illustrating a schematic configuration of a development processing apparatus according to a third embodiment. The figure which shows the flowchart of the developing process concerning 4th Embodiment. FIG. 10 is a process diagram illustrating development processing according to a fourth embodiment. The figure showing the reflected light intensity change from the resist film in image development. The figure which expressed the flow of the start of development, the flow of a developing solution, and the end of development on a time axis. The figure which shows the relationship between the timing of liquid flow, and dispersion | variation. The figure showing the reflected light intensity change from the resist film in image development. The figure which shows the relationship between the timing of liquid flow, and dispersion | variation. FIG. 10 is a flowchart illustrating development processing according to a fifth embodiment. FIG. 10 is a diagram illustrating a schematic configuration of a development processing apparatus according to a fifth embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Substrate 101 ... Substrate holding part 102 ... Rotating mechanism 103 ... Rinse nozzle 104 ... Developer supply nozzle 106 ... Ozone water 107 ... Developer 107: Developer film 112 ... Nozzle 130 ... Resist film 131 ... Exposure part

Claims (3)

A method for cleaning a developer supply nozzle that is used when developing an exposed photosensitive resist film and supplies a developer onto the resist film ,
A cleaning method for a developing solution supply nozzle, wherein an oxidizing liquid is supplied to the developing solution supply nozzle for cleaning. As the oxidizing liquid, ozone, oxygen, cleaning of the developer supply nozzle according to claim 1, wherein the carbon monoxide, and an aqueous solution containing at least one of hydrogen peroxide and supplying to the developing solution supply nozzle Method. After the developer supplied into the nozzle is switched to the oxidizing liquid and the inside of the nozzle is washed, the nozzle is immersed in a liquid receiving portion in which the oxidizing liquid is stored to face the resist film of the nozzle. 3. The method for cleaning a developer supply nozzle according to claim 1, wherein the surface to be cleaned is cleaned.

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