Abstract:
A method of substrate edge treatment includes forming a processing target film on a treatment target substrate, applying an energy line to a predetermined position on the processing target film to form a latent image on the processing target film, heating the treatment target substrate in which the latent image is formed on the processing target film, developing the processing target film after the heating, inspecting whether a residue is present at an edge of the treatment target substrate after the developing, and cleaning an end of the treatment target substrate to remove the residue at the edge of the treatment target substrate determined to be defective in the inspecting.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2006-039361, filed Feb. 16, 2006, the entire contents of which are incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a substrate edge treatment, and more particularly to a substrate edge treatment having a step of removing surface roughness of a substrate or a film that has adhered to the substrate. 
         [0004]    2. Description of the Related Art 
         [0005]    In a manufacturing process of a semiconductor device, an unnecessary part of a metal thin film formed at an end of a semiconductor wafer may be removed by etching in some cases. Various proposals have been conventionally made to suppress unintentional etching at the center of a wafer surface involved by scattering of an etchant in this process (see, e.g., Jpn. Pat. Appln. KOKAI Publication No. 2001-118824 or Jpn. Pat. Appln. KOKAI Publication No. 2002-299305). 
         [0006]    Further, removal of a metal at a wafer end has been also a problem in a liquid immersion exposure tool that has recently come into practical use. The liquid immersion exposure tool corresponds to a technique that fills a space between a resist film surface and a lens of an exposure tool with a liquid to perform exposure when effecting exposure with respect to the resist film formed on a treatment target substrate. As a tool used for such an exposure technique, there is one disclosed in, e.g., Jpn. Pat. Appln. KOKAI Publication No. 303114-1998. 
         [0007]    On the other hand, in liquid immersion exposure, an accuracy of a resist pattern cannot be possibly obtained because of, e.g., elution of a photosensitive agent or the like contained in a resist film into water, or penetration of water into the resist film. In order to avoid such problems, a water-repellent protection film is formed on the resist film. As the protection film, there are a developer soluble type protection film that can be solved in a developer and a solvent soluble type protection film that can be solved with a dedicated solvent. The protection film is removed after end of a series of coating/developing treatments. 
         [0008]    In particular, in case of using the developer soluble type protection film, when a developer is supplied to an upper side of a water-repellent protection film in a developing treatment after liquid immersion exposure, since the developer is repelled on a surface of the protection film from a substrate edge, the protection film cannot be sufficiently solved at the substrate edge and it may possibly remains as a residue even after end of the developing treatment. When etching step or the like is carried out in this state, the protection film remaining at the substrate edge serves as a mask, and sharp-pointed protrusions are generated at the substrate edge. These protrusions become particles to disadvantageously contaminate a carriage portion and others in an etching device. 
         [0009]    As explained above, in a state where the sharp-pointed protrusions remain at the substrate edge or a bevel of this part, when a resist film is coated/exposed/developed at a subsequent lithography step to form a resist pattern, an organic film enters a groove between the protrusions, and this film may not be possibly removed even after end of development. Further, when an etching step or the like is carried out in this state, the organic film remaining at the substrate edge become particles to disadvantageously contaminate a carriage portion or the like in an etching device. 
         [0010]    Therefore, realization of a substrate treatment that can remove a resist pattern even after end of development and avoid occurrence of particles even in a state where sharp-pointed protrusions remain at a substrate edge or a substrate bevel has been demanded. 
       BRIEF SUMMARY OF THE INVENTION 
       [0011]    According to the first aspect of the invention, there is provided a method of substrate edge treatment, which includes: 
         [0012]    forming a processing target film on a treatment target substrate; 
         [0013]    applying an energy line to a predetermined position on the processing target film to form a latent image on the processing target film; 
         [0014]    heating the treatment target substrate in which the latent image is formed on the processing target film; 
         [0015]    developing the processing target film after the heating; 
         [0016]    inspecting whether a residue is present at an edge of the treatment target substrate after the developing; and 
         [0017]    cleaning an end of the treatment target substrate to remove the residue at the edge of the treatment target substrate determined to be defective in the inspecting. 
         [0018]    According to a second aspect of the invention, there is provided a method of substrate edge treatment, which includes: 
         [0019]    forming a processing target film on a treatment target substrate; 
         [0020]    inspecting whether the processing target film is adhered to a rear surface at an edge of the treatment target substrate after the forming a processing target film; 
         [0021]    cleaning an end of the treatment target substrate to remove a residue at the edge of the treatment target substrate determined to be defective in the inspecting; 
         [0022]    applying an energy line to a predetermined position on the processing target film with respect to the treatment target substrate determined to be defective in the inspecting or with respect to the treatment target substrate determined to be defective in the inspecting and cleaned at the end thereof, thereby forming a latent image on the processing target film; 
         [0023]    heating the treatment target substrate in which the latent image is formed on the processing target film; and 
         [0024]    developing the processing target film after the heating. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0025]      FIG. 1  is a flowchart showing a manufacturing process of a semiconductor device according to a first embodiment; 
           [0026]      FIG. 2  is a view showing a schematic structure of a liquid immersion exposure tool that is used and explained in the first embodiment; 
           [0027]      FIG. 3A  is a schematic cross-sectional view for explaining a developer supply method in the first embodiment; 
           [0028]      FIG. 3B  is a schematic cross-sectional view for explaining the developer supply method in the first embodiment; 
           [0029]      FIG. 4  is a schematic cross-sectional view when the developer is put on a developer soluble type protection film; 
           [0030]      FIG. 5  is a schematic cross-sectional view showing a resist pattern after a developing treatment; 
           [0031]      FIG. 6  is a side view showing a schematic structure of a substrate edge observation/judgment mechanism described in the first embodiment; 
           [0032]      FIG. 7  is a schematic side view showing a substrate edge cleaning treatment described in the first embodiment; 
           [0033]      FIG. 8  is a schematic cross-sectional view showing the substrate edge cleaning treatment described in the first embodiment; and 
           [0034]      FIG. 9  is a flowchart showing a manufacturing process of a semiconductor element according to a second embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0035]    In embodiments explained below, whether a substrate edge is cleaned or whether the control advances to the next step without cleaning the substrate edge is controlled depending on presence of a residue of a processing target film at the substrate edge. Carrying out the cleaning treatment in this manner can eliminate particles produced due to a residue at the substrate edge and can improve a yield ratio of a semiconductor device. 
         [0036]    Embodiments according to the present invention will now be explained hereinafter with reference to the accompanying drawings. 
       First Embodiment 
       [0037]    As shown in a process flowchart of  FIG. 1 , an anti-reflection film coating material (e.g., ARC29A manufactured by NISSAN CHEMICAL INDUSTRIES, LTD.) is dropped and rotated to spread on a semiconductor substrate, and then a heat treatment is carried out to form an anti-reflection film having a film thickness of 80 nm (ST 101 ). An ArF chemically amplified resist film containing an acid producing agent is formed with a film thickness of 170 nm on the anti-reflection film (ST 102 ). Further, a developer soluble type protection film (e.g., TILC019 manufactured by TOKYO OHKA KOGYO CO., LTD.) is formed with a film thickness of 140 nm on the ArF chemically amplified resist film (ST 103 ). 
         [0038]    In more detail, the anti-reflection film, the chemically amplified resist, and the developer soluble type protection film are formed in accordance with a procedure of spreading each material on a treatment target substrate by a spin coat method and effecting a heat treatment to remove a solvent contained in a coating material. 
         [0039]    Then, the treatment target substrate is carried to a liquid immersion exposure tool. The liquid immersion exposure tool is used to transfer a semiconductor element pattern formed on a reticle onto the resist film, thereby forming a latent image (ST 104 ).  FIG. 2  schematically shows the liquid immersion exposure tool used in this embodiment. That is, in  FIG. 2 , a reticle stage  21  is arranged below a non-illustrated illumination optics, and a reticle  22  is disposed on this reticle stage  21 . The reticle stage  21  can move in parallel. A projection lens system  23  is arranged below the reticle stage  21 , and a wafer stage  24  is arranged below this projection lens system  23 . A semiconductor substrate  10  subjected to above-described treatment is provided on the wafer stage  24 . The wafer stage  24  moves in parallel together with the semiconductor substrate  10 . A support plate  27  is provided around the semiconductor substrate  10 . 
         [0040]    A fence  25  is disposed below the projection lens system  23 . A pair of water supply/drainage units  26  that supply water into the fence  25  and drain wafer from the fence  25  are provided beside the projection lens system  23 . At the time of exposure, a space between the substrate  10  and the projection lens system  23  in a region surrounded by the fence  25  and the projection lens  23  is filled with a liquid film of water. Exposure light exiting from the projection lens system  23  is transmitted through a water layer to reach an irradiation region. An image of a mask pattern (not shown) on the reticle  22  is projected onto the chemically amplified resist corresponding to the irradiation region, thereby forming a latent image. 
         [0041]    The substrate  10  having the latent image formed thereon by the above-described process is carried into a heating chamber (not shown), and subjected to a heat treatment under conditions of 130° C. and 60 seconds (ST 105 ). Subsequently, the treatment target substrate  10  is carried to a developing treatment unit (ST 106 ). In this developing treatment unit, when the treatment target substrate  10  is carried to a position directly above a scattered developer saucer cup (not shown), a pin first moves up to receive the substrate  10 , and then the substrate  10  is mounted on a spin chuck  31  to be subjected to vacuation as shown in  FIG. 3 . Further, a straight tubular nozzle  32  retracted in a nozzle standby portion discharges a developer  33  while scanning from one end toward the other end of the substrate  10 , whereby the developer  33  is put on an alkali soluble type protection film (not shown) formed on an uppermost surface of the treatment target substrate  10  to effect development. When the developer  33  is supplied, the developer soluble type protection film is dissolved, and then the resist film (not shown) having the latent image formed thereon is developed. After performing static development for 30 seconds, pure water is supplied to the treatment target substrate  10  to wash off the developer. Furthermore, the treatment target substrate  10  is rotated by the spin chuck  31  to be subjected to spin drying. 
         [0042]    However, as shown in  FIG. 4 , when the developer  33  is supplied to the highly water-repellent developer soluble type protection film  34 , the developer  33  is repelled at a given position at the edge of the substrate  10 . As a result, the developer soluble type protection film  34  cannot be dissolved, and the resist film  35  formed on a lower layer of the protection film  34  is not developed. As a result, as shown in  FIG. 5 , although a resist pattern  35 ′ is formed at the center of the substrate  10 , the protection film  34  and the resist film  35  may possibly remain as residues at the edge of the substrate  10 . 
         [0043]    Thus, as shown in  FIG. 6 , the edge of the substrate  10  is then observed by using a camera  37  disposed in the developing treatment unit while rotating the treatment target substrate  10 . Moreover, when the rotating substrate  10  returns to an observation start point, rotation of the substrate  10  is stopped, and observation of the edge of the substrate  10  is also terminated. Data obtained from observation by the camera  37  as substrate edge observing means is transferred to a substrate edge judgment mechanism  38  as needed. The substrate edge judgment mechanism  38  judges whether a residue of the alkali soluble type protection film  34  is present at the rim of the substrate  10  is judged from the data obtained from observation. If the residue of the developer soluble type protection film  34  is confirmed at the edge of the substrate  10 , an instruction can be issued to carry out a treatment of cleaning the edge of the substrate  10 . Additionally, when the residue is not present at the edge of the substrate  10  at all, an instruction can be issued to avoid the treatment of cleaning the edge, and an instruction can be issued to carry the treatment target substrate  10  from a coater/developer (ST 107 ). 
         [0044]    If the residue is present at the edge of the treatment target substrate  10  as a result of observation, a substrate edge cleaning treatment is effected (ST 108 ). As shown in  FIG. 7 , a substrate edge cleaning nozzle  43  and a substrate rear surface cleaning nozzle  44  are moved to predetermined positions near the substrate edge. Further, the developer  33  is discharged toward the edge of the substrate  10  while rotating the treatment target substrate  10 . When the developer  33  is also discharged from the rear surface cleaning nozzle  44 , the developer  33  discharged from the substrate edge cleaning nozzle  43  can be prevented from flowing toward the rear surface of the treatment target substrate  10 , thereby avoiding contamination of the spin chuck  31  holding the substrate  10 . Furthermore, the developer  33  is discharged from the substrate edge cleaning nozzle  43  in a direction parallel to a rotating direction of the substrate  10 . Moreover, a cleaning liquid (the developer  33 ) is discharged toward the outside of the substrate  10  apart from a tangential line at a supply position on a circular orbit described on the substrate  10  by the supply position. As a result, the developer  33  supplied to the edge of the substrate  10  can be prevented from flowing toward the center of the substrate  10 , and the cleaning liquid can be uniformly supplied to the developer soluble protection film  34  at the edge of the substrate  10 , thereby removing the protection film  34  included in this region. 
         [0045]    Then, after supplying the developer  33  at the edge, pure water is supplied to the upper surface and the rear surface of the substrate  10  to wash off the developer  33 , and the substrate  10  is rotated to be subjected to spin drying, thus terminating a series of developing treatments. 
         [0046]    When the developer soluble protection film  34  remaining at the edge of the substrate  10  is removed in the development unit in this manner, particles caused due to the substrate edge can be reduced at a lithography step and subsequent steps, and contamination of the coater/developer as well as the etching device can be suppressed. 
         [0047]    Although a substrate edge cleaning device  40  supplies the cleaning liquid toward the end of the substrate  10  from the substrate edge cleaning nozzle  44  to perform cleaning in this embodiment, the cleaning treatment for the edge of the substrate  10  is not restricted thereto. In a substrate edge cleaning treatment device  50  shown in  FIG. 8 , when the substrate is carried to a position directly above a cup (not shown), a pin (not shown) first moves up to receive the substrate  10 , and then the substrate  10  is mounted on a spin chuck  31  to be subjected to vacuation. 
         [0048]    Subsequently, an elevation driving unit  55  moves down a cleaning liquid holding top plate  51  to be brought into contact with an upper portion of a cleaning liquid holding bottom plate  53 . In this state, the cleaning liquid holding top plate  51  and the cleaning liquid holding bottom plate  53  form a ring-shaped concave portion surrounding an end of the substrate  10 . The concave portion is arranged to cover the entire edge of the substrate, and rotates the substrate  10  in this state. 
         [0049]    Then, a developer  33  is discharged from a periphery cleaning nozzle  43  toward the concave portion. Additionally, when the concave portion is filled with a fixed amount or more of the cleaning liquid  33 , the edge of the substrate  10  is immersed in the cleaning liquid  33 , thus performing a cleaning treatment. 
         [0050]    After effecting the cleaning treatment for a predetermined time, the developer  33  is drained from a drainage opening  54 . Then, when the holding top plate  51  is moved up, the concave portion is divided into the cleaning liquid holding top plate  51  and the cleaning liquid holding bottom plate  53 , and a small amount of the developer  33  remaining at the edge of the substrate  10  is laterally discharged by centrifugal force, thereby terminating the cleaning treatment. 
         [0051]    Such an embodiment can prevent the cleaning liquid  3  supplied to the edge of the substrate  10  from flowing toward the center of the substrate  10  and can uniformly supply the developer  33  to a region where the developer soluble type protection film  34  that has entered a damaged part of the edge of the substrate  10  should be removed, whereby an organic film included in this region can be removed. 
         [0052]    Further, although the single substrate edge cleaning treatment device simultaneously removes the organic film that has entered a damaged part on the rear surface side of the substrate  10  and the organic film that has entered damaged parts at the edge on the front surface side and the end side of the substrate  10  in this embodiment, the present invention is not restricted to this embodiment. After cleaning either the edge on the front surface side and the end side or the rear surface side of the substrate  10  first, the other may be cleaned. Furthermore, the treatment device may be changed depending on cleaning at the edge on the front surface side and the end side and cleaning on the rear surface side of the substrate  10 , and any device may be used as long as an effect equivalent to that described in conjunction with this embodiment can be obtained. 
       Second Embodiment 
       [0053]    A second embodiment uses the cleaning treatment system and the cleaning treatment described in conjunction with the first embodiment to remove a resist film that has entered a space between protrusions formed at a substrate edge by a reactive ion etching (RIE) device at the time of resist coating. 
         [0054]    For example, when forming a trench capacitor, a silicon nitride film and a silicon oxide film are sequentially formed on a silicon substrate surface by a hot wall type CVD device or the like. Then, coating/exposure/development of a resist film is performed on the silicon oxide film to form a resist pattern. However, the resist film may remain at a position where the resist film does not essentially remain at a substrate edge in some cases. In this state, the resist pattern is used as a mask to sequentially etch the silicon oxide film, the silicon nitride film, and the silicon substrate, thereby forming a trench serving as a capacitor. At this time, the resist film remaining at the substrate edge becomes a mask, and sharp-pointed protrusions are generated at the substrate edge. Such sharp-pointed protrusions are produced when a plasma does not sufficiently reach a wafer edge, RIE etching of the silicon oxide film or the silicon nitride film is insufficient, and the remaining silicon oxide film and silicon nitride film become masks. 
         [0055]    When the sharp-pointed protrusions are produced at the substrate edge in this manner, the resist film enters a groove between the sharp-pointed protrusions and cannot be removed at the time of coating and forming the resist film at the next lithography step. When the substrate is carried in this state, the resist film that has entered the space between the protrusions at the substrate edge become particles to contaminate a carriage portion in a coater/developer. Moreover, when an etching process or the like is performed in this state, the resist film at the substrate edge disadvantageously contaminates a carriage portion or the like in an etching device. 
         [0056]    A process according to the second embodiment will now be described in detail with reference to  FIG. 9 . Like the first embodiment, an anti-reflection film having a film thickness of 80 nm is formed on the semiconductor substrate (ST 901 ). An ArF chemically amplified resist film containing an acid producing agent is formed with a film thickness of 170 nm on the anti-reflection film (ST 901 ). Although not shown, the chemically amplified resist film is formed in accordance with the following known procedure. 
         [0057]    First, the treatment target substrate is supplied to a spin chuck to be held at a predetermined position. Subsequently, a predetermined amount of a coating liquid is dispensed from a coating liquid dispensing nozzle to the treatment target substrate held by the spin chuck, and this coating liquid is spread on the treatment substrate to form a coating film (see  FIG. 3 ). Then, the treatment target substrate  10  is rotated for a predetermined time and adjusted to have a desired film thickness. 
         [0058]    Subsequently, like  FIG. 7 , a cleaning liquid, e.g., cyclohexanone is supplied from a rear surface cleaning nozzle  44  to the rear surface of the treatment target substrate  10 . Supply of this cleaning liquid washes off the chemically amplified resist liquid that has adhered to the rear surface of the treatment target substrate  10 . It is to be noted that, at this time, a thinner as a cleaning liquid that performs fine cleaning is belched out to the substrate edge to carry out an edge cut treatment of cutting the resist film at the substrate edge. Thereafter, supply of the thinner is stopped, and the thinner that has adhered to the rear surface of the treatment target substrate  10  is spun off, whereby the treatment target substrate  10  wet with the thinner is dried. However, the resist film that has entered the space between the protrusions produced at the substrate edge at the etching step cannot be completely removed even if cleaning is performed with the thinner. 
         [0059]    Therefore, after end of the series of coating processes, like  FIG. 6  according to the first embodiment, the substrate edge is observed by using a camera  37  disposed in a resist coating treatment unit while rotating the treatment target substrate  10  (ST 903 ). Moreover, when the rotating substrate  10  returns to an observation start point, rotation of the substrate  10  is stopped, and observation of the substrate edge is also terminated. Data obtained from observation by the camera  37  as substrate edge observing means is transferred to a substrate edge judgment mechanism  38  as needed. 
         [0060]    The substrate edge judgment mechanism  38  judges whether a residue of the resist film that has entered the space between the protrusions is present at the substrate edge from the data obtained from observation (ST 904 ). If the residue of the resist film is confirmed, an instruction can be issued to carry out a treatment of cleaning off the residue. Additionally, if the residue is not present at all, an instruction can be issued to prevent the edge cleaning treatment from being effected, and an instruction to carry the treatment target substrate from the coater/developer can be issued. 
         [0061]    Then, the substrate edge cleaning treatment is carried out. As a substrate edge cleaning method, such a conformation as shown in  FIG. 8  is desirable. In a substrate edge cleaning treatment device  50 , when the substrate  10  is carried to a position directly above a cup, a pin first moves up to receive the substrate, and then the substrate  10  is mounted on the spin chuck  31  to be subjected to vacuation. Subsequently, an elevation driving unit  55  moves down a cleaning liquid holding top plate  51  to be brought into contact with an upper portion of a cleaning liquid holding bottom plate  53 . In this state, the cleaning liquid holding top plate  51  and the cleaning liquid holding bottom plate  53  form a ring-shaped concave portion to surround the substrate end. Further, the concave portion is arranged to cover the entire edge of the substrate  10 , and the substrate  10  is rotated in this state. 
         [0062]    Then, the cleaning liquid  33  is discharged from a discharge opening  43  toward the concave portion. Furthermore, when the concave portion is filled with a fixed amount or more of the cleaning liquid  33 , the edge of the substrate  10  is immersed in the cleaning liquid  33 , thus effecting the cleaning treatment. 
         [0063]    After performing the cleaning treatment for a predetermined time, the developer  33  is drained from a drainage opening  54 . Subsequently, when the cleaning liquid holding top plate  51  is moved up, the concave portion is divided into the cleaning liquid holding top plate  51  and the cleaning liquid holding bottom plate  53 , and a small amount of the cleaning liquid  33  remaining at the edge of the substrate  10  is laterally discharged by centrifugal force, thereby terminating the cleaning treatment. 
         [0064]    Such an embodiment can prevent the cleaning liquid supplied to the substrate edge from flowing toward the center of the substrate and can uniformly supply the cleaning liquid to a region where the chemically amplified resist film that has entered a damaged part at the substrate edge should be removed, thus removing the chemically amplified resist film included in this region. 
         [0065]    A semiconductor element pattern is transferred onto the resist film of the substrate  10  by a scan exposure tool to form a latent image. Thereafter, a heat treatment and a developing treatment are performed (ST 905  to ST 907 ). 
         [0066]    When the coating/developing treatment is performed in this manner, the coater/developer or a carriage portion or the like in an etching device used at the next step can be prevented from being contaminated. 
         [0067]    Moreover, although the single substrate edge cleaning treatment device simultaneously removes the organic film that has entered a damaged part on the rear surface side of the substrate and the organic film that has entered damaged parts at the edge on the substrate front surface side and the end side in this embodiment, the present invention is not restricted to this embodiment. After cleaning either the edge on the front surface side and the end side or the rear surface side of the substrate, the other may be cleaned. Additionally, the treatment device may be changed depending on cleaning at the edge on the front surface side and the end side and cleaning on the rear surface side of the substrate, and any device may be used as long as the same effect as that described in conjunction with this embodiment can be obtained. 
         [0068]    It is to be noted that, as the cleaning liquid supplied from the substrate edge cleaning treatment nozzle to the substrate, there are organic solvents, e.g., γ-butyrolactone, PGMEA (propylene glycol monomethylethylacetate), PGME (propylene glycol monomethylethyl), alcohol and others as well as cyclohexanone, for example. However, the organic solvents are not restricted thereto, and any organic solvents can be used as long as they can dissolve the chemically amplified resist film to be cleaned off and removed. 
         [0069]    Although the present invention has been explained based on the foregoing embodiments, the present invention is not restricted these embodiments. Although the fine pattern forming material has been explained as the example in the foregoing embodiments, the present invention can be applied to, e.g., a resist chemical and others. 
         [0070]    Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.