Patent Publication Number: US-2009219504-A1

Title: Substrate conveyor apparatus, substrate conveyance method and exposure apparatus

Description:
This application is a divisional of application Ser. No. 11/235,130, filed Sep. 27, 2005, which is incorporated in its entirety herein by reference. This application is also based upon and claims priority from Japanese Patent Application No. 2004-310919, filed Oct. 26, 2004. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention pertains to a substrate conveyor apparatus that carries a substrate on which patterns are formed to a substrate exposure apparatus equipped with a substrate conveyance method and a substrate conveyor apparatus. 
     With a reticle (also known as a mask) used in next-generation lithography such as EPL and EUVL, a common problem is the weakness that a pellicle that prevent the adhering of defect-causing particles onto the reticle pattern face cannot be used. 
     As a means to resolve this problem, there is a proposal to attach a protective cover when a reticle is not used and only remove it during exposure. For example, refer to U.S. Pat. No. 6,239,863. 
     SUMMARY OF THE INVENTION 
     However, in the above method, there was the problem that the protective cover for the reticle used during exposure is left in a state wherein the inner surface of the protective cover is exposed, and it is easy for particles and the like to become adhered to the inner surface of the protective cover. 
     The present invention is intended to resolve the conventional problems concerned, therefore the object is to provide a substrate conveyor apparatus and a substrate exposure apparatus equipped with a substrate conveyance method and a substrate conveyor apparatus thereof that can easily and reliably prevent contamination of the inner surface of the protective cover when a substrate is used. 
     In the first viewpoint of the present invention, a substrate conveyor apparatus that, being a substrate conveyor apparatus that carries substrates on which patterns are formed, carries the substrates in a state protected by a protective cover when the substrate is not used, and is characterized by having a cover protection means that covers the inner surface of the protective cover when the substrate is used. 
     In the second viewpoint of the present invention, the cover protection means is characterized by covering the inner surface of the protective cover when the substrate is used in exposure. 
     In the third viewpoint of the present invention, the protective cover comprises a plurality of cover members that cover the substrate and are disposed so as to be attachable and removable, and the cover protective means is characterized by holding the plurality of cover members in a standby position in a closed state. 
     In the fourth viewpoint of the present invention, the cover protective means is characterized by, after carrying the substrate along with one part of the plurality of cover members to the substrate exposure position, returning the one part of the cover members to the standby position and bringing the plurality of cover members into a closed state. 
     In the fifth viewpoint of the present invention, the closed state of the plurality of cover members is characterized by being a state in which the plurality of cover members are sealed. 
     In the sixth viewpoint of the present invention, the protective cover comprises a cover member that covers the pattern on the substrate and is disposed so as to be attachable and removable, and the cover protective means is characterized by holding the cover member in a standby position in a state mounted to a dummy member that is similar to the shape of the substrate. 
     In the seventh viewpoint of the present invention, the standby position is characterized by being a position wherein the substrate is aligned. 
     In the eighth viewpoint of the present invention, the standby position is characterized by being a position wherein the cover member is removed from the substrate. 
     In the ninth viewpoint of the present invention, the standby position is characterized by being a library part that stores the substrate in an exposure atmosphere. 
     In the tenth viewpoint of the present invention, the standby position is characterized by grounding the protective cover. 
     In the eleventh viewpoint of the present invention, a substrate conveyor apparatus that, being a substrate conveyor apparatus that carries substrates on which patterns are formed, carries the substrate in a state protected by a protective cover when the substrate is not used, and is characterized by having a grounding means that grounds the substrate or the protective cover. 
     In the twelfth viewpoint of the present invention, the grounding means is characterized by being provided on the setting machine that sets the substrate or the protective cover. 
     In the thirteenth viewpoint of the present invention, the substrate is characterized by being grounded via the protective cover. 
     In the fourteenth viewpoint of the present invention, a substrate conveyance method that, being a substrate conveyance method that carries substrates on which patterns are formed, carries the substrates in a state protected by a protective cover when the substrate is not used, and is characterized by holding the protective cover on standby so that the inner surface of the protective cover is covered when the substrate is used. 
     In the fifteenth viewpoint of the present invention, the substrate exposure apparatus is characterized by being equipped with the substrate conveyor apparatus. 
     In the substrate conveyor apparatus of the present invention, when the substrate is used, the inner surface of the protective cover is covered by a cover protection means, therefore when the substrate is used, contamination of the inner surface of the protective cover can be easily and reliably prevented. 
     In addition, in the substrate conveyor apparatus of the present invention, the substrate or the protective cover are grounded by a grounding means, therefore electrostatic charging of the substrate or the protective cover can be easily and reliably prevented. 
     In the substrate conveyance method of the present invention, when the substrate is used, the protective cover is held in standby in a state wherein the inner surface of the protective cover is covered, therefore contamination of the inner surface of the protective cover can be easily and reliably prevented. 
     In the exposure apparatus of the present invention, a substrate with little contamination is used, obtaining a product with high yield. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         FIG. 1  is an illustration showing a first embodiment of the substrate conveyor apparatus of the present invention. 
         FIG. 2  is an illustration showing a reticle carrier from  FIG. 1 . 
         FIG. 3  is an illustration showing the details of a CFP stage from  FIG. 1 . 
         FIG. 4  is an illustration showing the state exposing the reticle from the CFP in  FIG. 3 . 
         FIG. 5  is an illustration showing a state wherein the reticle is conveyed from a CFP stage to a reticle stage of  FIG. 1 . 
         FIG. 6  is an illustration showing the state in the CFP stage of  FIG. 1  where the CFP is in standby. 
         FIGS. 7   a - 7   b  are illustrations showing a second embodiment of the substrate conveyor apparatus of the present invention. 
         FIG. 8  is an illustration showing a third embodiment of the substrate conveyor apparatus of the present invention. 
         FIG. 9  is an illustration showing an embodiment of the exposure apparatus of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Below we will explain the details of embodiments of the present invention using drawings. Note that the present invention is not limited to the following embodiments. 
     FIRST EMBODIMENT 
       FIG. 1  shows the first embodiment of the substrate conveyor apparatus of the present invention. 
     This substrate conveyor apparatus is provided adjacent to an exposure chamber  13  wherein reticle stage  11  and the like are disposed. On one side of reticle chamber  13 , a robot chamber  17  is provided wherein a vacuum robot  15  is disposed. On one side of robot chamber  17 , a vacuum reticle library  19  is provided, and on the other side a clean filter pod opener  21  (hereafter called “CFP opener”) is provided. Exposure chamber  13 , robot chamber  17 , vacuum reticle library  19  and CFP opener  21  are in vacuum atmosphere. 
     In the position where robot chamber  17  faces exposure chamber  13 , a load-lock chamber  23  is disposed. Load-lock chamber  23  communicates to robot chamber  17  via second gate valve  25 . In addition, load-lock chamber  23  communicates to atmospheric air via a first gate valve  27 . 
     On the other side of load-lock chamber  23 , a reticle carrier opener  31  is disposed via a second atmospheric robot  29 . On the other side of reticle carrier opener  31 , an atmospheric reticle library  35  is disposed via a first atmospheric robot  33 . 
     With the above substrate conveyor apparatus, in the atmospheric reticle library  35 , as shown in  FIG. 2 , an EUVL reticle  37  used in exposure is placed in a state doubly protected by a reticle carrier  39  and a clean filter pod (hereafter called “CFP”)  41 . CFP  41  has the function of a protective cover protecting reticle  37  in a low-pressure atmosphere. 
     The reticle carrier  39  placed in atmospheric reticle library  35  is conveyed by the first atmospheric robot  33  to reticle carrier opener  31 . Then, reticle carrier  39  is identified by reticle carrier ID reader  43 . At this reticle carrier opener  31  reticle carrier  39  is opened and CFP  41  is exposed. The exposed CFP  41  is heated about 2-3 degrees Celsius by temperature compensation lamp  45 . The heated CFP  41  is conveyed by a second atmospheric robot  29  onto load-lock chamber  23  wherein only the first gate valve  27  is opened. Note that the steps from reticle carrier opener  31  to load-lock chamber  23  are in a clean environment. 
     In load-lock chamber  23  accommodating the CFP  41 , vacuum evacuation occurs in a state where the first gate valve  27  and second gate valve  25  are closed. When a specified state of vacuum is achieved in load-lock chamber  23 , only second gate valve  25  opens and CFP  41  is conveyed to vacuum reticle library  19  by vacuum robot  15 . 
     In vacuum reticle library  19 , for example around 5 CFP&#39;s, each of which houses a reticle, are stored. 
     The reticle  37  is held at a specified temperature by a temperature adjustment mechanism (not shown). The reticle  37  stored in CFP  41  is identified by reticle ID reader  47 . The identified reticle  37  is conveyed by vacuum robot  15  to CFP opener  21  while housed in CFP  41 . 
     In CFP opener  21 , CFP  41  is opened and reticle  37  exposed. 
     In this embodiment, as shown in  FIG. 3 , the CFP  41  conveyed to CFP opener  21  is set on CFP stage  49 . CFP  41  comprises upper cover member (upper lid)  51  and lower cover member (lower lid)  53 . Then, as shown in  FIG. 4 , by lowering CFP stage  49  the exterior of upper cover member  51  is locked by locking member  57  on the upper end of support member  55 , exposing reticle  37 . 
     In this embodiment, at the lower region of CFP stage  49 , a reference microscope  59  is disposed for performing prealignment of reticle  37 . Then, a prealignment mark  37   a  formed on the lower surface of reticle  37  is detected by reference microscope  59  from a perforating hole  49   a  formed in CFP stage  49  and a transparent window  53   a  established in lower cover member  53  through transparent window  53   a , and prealignment occurs by driving CFP stage  49 . At this time, the reticle ID can be confirmed by detecting the reticle ID, such as a bar code, through the transparent window  53   a  in lower cover member  53 . 
     The reticle  37  that has completed prealignment, as shown in  FIG. 5 , is conveyed housed in the lower cover  53  of CFP  41  to reticle stage  11  by conveyor arm  61  of vacuum robot  15 . In reticle stage  11 , electrostatic chuck  63  is disposed with chuck surface  63   a  facing down. Then, in a state where reticle  37  is pushed to chuck surface  63   a  of electrostatic chuck  63  by conveyor arm  61  via lower cover member  53 , the upper surface of reticle  37  is chucked to chuck surface  63   a  by turning on electrostatic chuck  63 . 
     After chucking reticle  37 , conveyor arm  61  carries lower cover member  53  to CFP opener  21 , and lower cover member  53  is set on CFP stage  49 , which is in the descended position shown in  FIG. 4 . Then, the upper cover member  51  and lower cover member  53  of CFP  41  are attached by raising CFP stage  49 , and the inside of upper cover member  51  and lower cover member  53  is sealed airtight. In this embodiment, the closed CFP  41  is held during exposure inside CFP opener  21  in that state. Note that if the CFP opener  21  and prealignment part is separately located, it is acceptable to hold closed CFP  41  at the prealignment part. Also, it is acceptable to convey closed CFP  41  to vacuum reticle library  19  and hold the closed CFP  41  at the vacuum reticle library  19 . 
     When exposure is completed and the exchange of reticle  37  of reticle stage  11  occurs, the upper cover member  51  and lower cover member  53  of the CFP  41  held in the state shown in  FIG. 6  are separated by lowering CFP stage  49  and lowering the lower cover member  53  (corresponding to the state in  FIG. 4  without reticle  37 ), and lower cover member  53  is conveyed to the exchange position of the reticle  37  by conveyor arm  61 . 
     Then, with the lower cover member  53  in contact with reticle  37 , which is attached to electrostatic chuck  63  (refer to  FIG. 5 ), reticle  37  is set on lower cover member  53  by turning off electrostatic chuck  63 . In this state, reticle  37  is conveyed to CFP opener  21  by conveyor arm  61  and lower cover member  53 , on which is set reticle  37 , is set on CFP stage  49 , which is in the descended position as shown in  FIG. 4 . Then, by raising CFP stage  49 , the upper cover member  51  of CFP  41  and lower cover member  53  are sealed (refer to  FIG. 3 ) and CFP  41  is sealed airtight while reticle  37  is contained inside CFP  41 . 
     In the above substrate conveyor apparatus and method, when reticle  37  is used in exposure, the upper cover member  51  and lower cover member  53  of CFP  41  are closed and the inner surfaces of upper cover member  51  and lower cover member  53  are covered; therefore, when reticle  37  is used in exposure, contamination of the inner surface of CFP  41  can be easily and reliably prevented. Then, because the inner surface of CFP  41  is not contaminated, there is very little contamination of reticle  37 . 
     EMBODIMENT 2 
       FIG. 7  shows a second embodiment of the substrate conveyor apparatus of the present invention. 
     Note that in this embodiment, the same members as in the first embodiment are assigned the same symbols, so detailed explanation has been omitted. 
     In this embodiment, as shown in  FIG. 7(   a ), the cover member  65  that is a protective cover is mounted so that it can be attached and removed and so that it covers only pattern  37   b  on reticle  37 . 
     Then, as shown in  FIG. 7  ( b ), cover member  65  is conveyed as mounted to cover member  65  by conveyor arm  61  to electrostatic chuck  63  of reticle stage  11 , then only reticle  37  is chucked to electrostatic chuck  63 . 
     On the other hand, as shown in  FIG. 7(   c ) cover member  65 , which remains on conveyor arm  61 , is conveyed to a standby part by conveyor arm  61 . In the standby part, as shown in  FIG. 7(   d ), a dummy part  67  that is similar to the shape of reticle  37  is disposed, and by mounting cover member  65  to this dummy member  67 , the inner surface of cover member  65  is covered and protected by dummy member  67 . 
     Then, when exposure is completed and the exchange of reticle  37  of reticle stage  11  occurs, cover member  65  is released from dummy member  67  and conveyed to the exchange position of the reticle  37  by conveyor arm  61 . Then, after mounting cover  65  to the reticle  37  chucked to electrostatic chuck  63 , reticle  37  is removed by turning electrostatic chuck  63  off. The removed reticle  37  is conveyed along with cover member  65  by conveyor arm  61  to vacuum reticle library  19 , for example. 
     In this embodiment the similar result as in the first embodiment can be obtained. 
     EMBODIMENT 3 
       FIG. 8  shows a third embodiment of the substrate conveyor apparatus of the present invention. 
     Note that in this embodiment, the same members as in the first embodiment are assigned the same symbols, so detailed explanation has been omitted. 
     In this embodiment, a stage-side conductive layer  69  made of aluminum is formed on the upper surface of CFP stage  49  (setting machine) of CFP opener  21 , for example. This stage-side conductive layer  69  is grounded via ground wire  71 . 
     On the other hand, on the side surface of lower cover member  53  of CFP  41 , when lower cover member  53  is set on stage-side conductive layer  69 , a lower cover conductive layer  53   b  that contacts stage-side conductive layer  69  is formed. This lower cover conductive layer  53   b  contacts an upper cover conductive layer  51  b formed on upper cover member  51  when upper cover member  51  is set on lower cover member  53 . Also, on the upper surface of reticle  37 , when upper cover member  51  is set, a reticle conductive layer  37   b  is formed that contacts upper cover conductive layer  51   b.    
     With this embodiment, the similar result as in the first embodiment can be obtained, but in this embodiment, at CFP stage  49 , lower cover member  53  of CFP  41 , upper cover member  51 , or reticle  37  are grounded, therefore electrostatic charging of lower cover member  53 , upper cover member  51 , or reticle  37  can be easily, reliably prevented. Accordingly, adhesion of particles to these members and the like can be reduced. 
     Note that in this embodiment, we explained an example where lower cover member  53 , upper cover member  51 , or reticle  37  are grounded at CFP stage  49 ; however, it is acceptable for example to ground the plate of vacuum reticle library  19  on which CFP  41  is set, the setting machine of load-lock chamber  23 , or the parts (end effectors) of vacuum robot  15  or atmospheric robot  29  that contact CFP  41 . In these cases, there are no need to ground at every location; it is acceptable to ground just those locations where one wants to prevent charging of CFP  41  and reticle  37 . 
     Also, in the above embodiment, conductive layers  51   b  and  53   b  are formed on upper cover member  51  and lower cover member  53  of CFP  41  and when upper cover member  51  and lower cover member  53  are closed, they create a configuration where both are electrically connected. However, if upper cover member  51  and lower cover member  53  are made of conductive material (for example, aluminum), there is no special need to form a conductive layer. Then, just by placing CFP  41  on CFP stage  49  it becomes grounded. However, in case there is an insufficient electrical contact, it is acceptable to dispose a mechanical means of making a reliable electrical contact (for example a conductive needle). 
     The same applies to conductive layer  51  b of CFP  41  upper cover member  51  and conductive layer  37   b  of reticle  37 . 
     Also, in the above embodiment, a reticle-side conductive layer  37   b  is formed only on the upper surface of reticle  37 , but it is also acceptable to form a conductive layer on a side surface or lower surface (surface where circuit pattern is formed) of the reticle. In this case, it is necessary to form the conductive layer so that it does not harm exposure, inspection, or various alignments. Also, stage-side conductive layer  69  was formed on the entire upper surface of CFP stage  49 , but it is also acceptable to form only a portion of stage-side conductive layer  69 , such that at least reticle  37  or CFP  41  can be grounded. 
     Also, as shown in  FIG. 7 , in the case that cover member  65  is established only on the pattern surface  37   b  of reticle  37 , because the upper surface of reticle  37  is exposed, grounding of reticle  37  can be made directly from its upper surface, and it is also possible to ground in the same manner as the above example via cover member  65 . 
     Embodiment of Exposure Apparatus 
       FIG. 9  shows the patterning of the EUV light lithography system inside the exposure chamber  13  of  FIG. 1 . Note that in this embodiment, the same members as in the first embodiment are assigned the same symbols. In this embodiment, EUV light is used as the exposure light. EUV light has a wavelength of 0.1˜400 nm, and for this embodiment a wavelength of 1˜50 nm is preferable. The projection image is formed by using an image optics system  101 , and a reduction image of the pattern on the reticle  37  is formed on wafer  103 . 
     The pattern exposed onto wafer  103  is determined by the reflective type reticle  37  disposed on the lower side of reticle stage  11  via electrostatic chuck  63 . This reflective type reticle  37  is loaded in and out by the vacuum robot  15  of the above embodiment (indication of vacuum robot  15  on the drawing is omitted). Also, wafer  103  is set on top of wafer stage  105 . Typically, exposure is done by step and scanning exposure. 
     The EUV light used as the illumination light during exposure has low transparency in atmospheric air; for this reason the light path traveled by EUV light is enclosed by vacuum chamber  106 , which maintains a vacuum using an appropriate vacuum pump  107 . Also, EUV light is generated by a laser plasma X-ray source. The laser plasma X-ray source comprises laser source  108  (operated as an excitation light source) and xenon gas supply apparatus  109 . The laser plasma X-ray source is enclosed by vacuum chamber  110 . The EUV light generated by the laser plasma X-ray source passes through window  111  of vacuum chamber  110 . 
     Laser source  108  generates laser light having a wavelength below ultraviolet, for example using a YAG laser or excimer laser. The laser light from laser source  108  is focused and exposed in a flow of xenon gas ejected from nozzle  112  (supplied from xenon supply apparatus  109 ). When laser light is exposed in the xenon flow, the laser light sufficiently warms the xenon gas, generating plasma. When the xenon gas molecules excited by the laser fall into a low energy state, EUV light photons are emitted. 
     A parabolic mirror  113  is disposed adjacent to the xenon gas ejection part. Parabolic mirror  113  forms a condenser optics system and is disposed so that the focus point is adjacent to the position where xenon gas is emitted from nozzle  112 . EUV light is reflected on the multi-layer film of parabolic mirror  113  and reaches condenser mirror  114  through window  111  of vacuum chamber  110 . Condenser mirror  114  focuses EUV light on reflecting reticle  37  and reflects it. EUV light is reflected by condenser mirror  114  and illuminates a specific portion of reticle  37 . That is to say, parabolic mirror  113  and condenser  114  compose the illumination system of this apparatus. 
     Reticle  37  has a multilayer film that reflects EUV light and an absorbent pattern layer for forming a pattern. By reflecting EUV light with reticle  37 , the EUV light is “patternized.” The “patternized” EUV light reaches wafer  103  through projection system  101 . 
     The image optics system  101  of this embodiment comprises  4  reflective mirrors: concave first mirror  115   a , convex second mirror  115   b , convex third mirror  115   c  and concave fourth mirror  115   d . A multilayer film that reflects EUV light is provided on each mirror  115   a˜d.    
     The EUV light reflected from reticle  37  is reflected sequentially from first mirror  115   a  through to fourth mirror  115   d , forming a reduced (for example, ¼, ⅕, ⅙) image of the reticle pattern. Image optics system  101  is made to be telecentric on the image side (wafer  103  side). 
     Reticle  37  is supported on at least the X and Y planes by movable reticle stage  11 . Wafer  103  is supported by wafer stage  105 , which is preferably movable in the X, Y, and Z directions. When the die on wafer  103  is exposed, EUV light is exposed to a specific region on reticle  37  by illumination system  101 , and reticle  37  and wafer  103  are moved relative to image optics system  101  at a specified speed according to the reduction rate of image optics system  101 . In this manner, the reticle pattern is exposed in the specified exposure area (toward the die) on wafer  103 . 
     At time of exposure, it is desirable that wafer  103  be disposed behind a partition  116  so that the gas that is generated from the resist on wafer  103  not influence mirrors  115   a˜d  of image optics system  101 . Partition  116  has an opening  116   a , and EUV light is exposed through it from mirror  115   d  to wafer  103 . The space inside partition  116  is evacuated by vacuum pump  117 . In this manner, refuse in the form of gas generated by illuminating the resist is prevented from adhering to mirrors  115   a˜d  or to reticle  37 . For that reason, deterioration of the optical properties thereof is prevented. 
     With the exposure apparatus of this embodiment, conveyance of reticle  37  is performed by the above substrate conveyor apparatus; therefore a high yield product can be obtained using a reticle  37  with little contamination. 
     Supplemental Items for the Embodiments 
     In the above we explained the present invention by means of the above embodiments, but the technical scope of the present invention is not limited to the above embodiments. For example, the following forms are acceptable. 
     (1) For the above embodiment, we explained an example where the inner surface of CFP  41  is covered when reticle  37  is used in exposure, but it is also acceptable for example to cover the inner surface of CFP  41  when reticle  37  is used in inspection, cleaning, etc. 
     (2) For the above first embodiment, we explained an example where the protective cover for reticle  37  is composed of two members which are an upper cover member  51  and a lower cover member  53 , but it is also acceptable for example to be composed of 3 or more members. 
     For the above embodiment, we explained an example of an exposure apparatus that uses EUV light, but other than this it is also acceptable to broadly apply an exposure apparatus using charged particle beams, i-line, g-line, KrF, ArF, F2 and the like.