Patent Publication Number: US-RE47456-E

Title: Pattern transfer apparatus and method for fabricating semiconductor device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a reissue of U.S. Pat. No. 8,709,955, issued on Apr. 29, 2014 from U.S. patent application Ser. No. 13/422,942, which is based upon and claims the benefit of priority from Japanese Patent Application No. 2010-189465, filed on Aug. 31, 2011; the. The entire contents of which the above-identified applications are incorporated herein by reference. 
     FIELD 
     Embodiments described herein relate generally to a pattern transfer apparatus and methods for fabricating a semiconductor device. 
     BACKGROUND 
     Attention is being given to a nanoimprinting method in which a pattern formed at an original plate is transferred to transferring substrates in a semiconductor device fabrication process. The nanoimprinting method is a method in which an original plate at which a pattern to be transferred is formed (i.e., a template) is pressed on a resist layer of an imprinting material applied on a substrate, and then the resist layer is cured to transfer the pattern to the resist layer. In the nanoimprinting pattern formation method, breakage and defects sometimes occur at templates since imprinting is done by firmly pressing the templates to wafers. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic perspective view of a pattern transfer apparatus according to a first embodiment; 
         FIGS. 2A and 2B  are plan views of a template and a wafer in the pattern transfer apparatus of  FIG. 1  illustrating the relationship between the template and the shot regions of the wafer; 
         FIGS. 3A and 3B  are cross-sectional views illustrating an imprinting method employed at the shot region SA of  FIG. 2A ; 
         FIGS. 4A and 4B  are cross-sectional views illustrating an imprinting method employed at the shot region SC of  FIG. 2A ; and 
         FIGS. 5A and 5B  are cross-sectional views illustrating an imprinting method employed at the shot region SB of  FIG. 2A . 
     
    
    
     DETAILED DESCRIPTION 
     A pattern transfer apparatus according to the present embodiment is provided with a transfer region selecting part. When performing pattern transfer from a template provided with N transfer regions (N is an integer of 2 or larger) to a transferring substrate a plurality of times, the transfer region selecting part selects 1 to N−1 transfer regions to be used to perform the transfer to regions of the transferring substrate corresponding to part of the N transfer regions such that the number of the transfer to be performed using each of the N transfer regions is evened out. 
     The pattern transfer apparatus and methods for fabricating a semiconductor device according to the present embodiments will be described below with reference to the accompanying drawings; however, note that the present invention is not limited to these embodiments. 
     First Embodiment 
       FIG. 1  is a schematic perspective view of a pattern transfer apparatus according to a first embodiment. 
     As illustrated in  FIG. 1 , the pattern transfer apparatus is provided with a stage  1  that holds a wafer W used as a transferring substrate, a template TM to be used for imprinting, a nozzle  4  that delivers an imprinting material onto the wafer W, and an ultraviolet irradiating unit  3  that irradiates the imprinting material on the wafer W with ultraviolet light via the template TM. 
     The template TM is provided with N transfer regions (N is an integer of 2 or larger). The transfer regions can be provided such that a one-to-one correspondence is established between the transfer regions and the chip regions of the wafer W. The nozzle  4  is coupled to a tank  5  that stores the imprinting material, and can be moved above the wafer W back and forth, right and left, and up and down. 
     The stage  1  can be moved back and forth, and right and left. The template TM can be moved up and down. The stage  1  is provided with driving parts  6  and  7  that move the stage  1  back and forth, and right and left. The template TM is provided with a driving part  8  that moves the template TM up and down. 
     The pattern transfer apparatus is further provided with a driving control unit  9  which drivingly controls the driving parts  6  to  8  so that the number of pattern transfer to be performed using each of the N transfer regions of the template TM is evened out. The driving control unit  9  is provided with a transfer region selecting part  11  and a transfer order setting part  12 . The transfer region selecting part  11  can select the 1 to N−1 transfer regions from among the N transfer regions to even out the number of pattern transfer to be performed using each of the N transfer regions of the template TM. The transfer order setting part  12  can set the order of pattern transfer from the template TM to the wafer W such that nonselected one(s) of the transfer regions of the template TM does not collide with transfer-performed region(s) of the wafer W. 
       FIGS. 2A and 2B  are plan views in the pattern transfer apparatus of  FIG. 1  illustrating the relationship between the template and the shot regions of the wafer. 
     As illustrated in  FIG. 2B , the template TM is provided with four transfer regions T 1  to T 4 ; as illustrated in  FIG. 2A , the wafer W is provided with a pattern nonforming region R 1  and a pattern forming region R 2 . The pattern forming region R 2  is provided with shot regions SH. Each shot region SH is provided with chip regions C 1  to C 4 . The transfer regions T 1  to T 4  of the template TM are allowed to respectively correspond to the chip regions C 1  to C 4  of the wafer W. 
     To begin with, an imprinting material is applied through the nozzle  4  onto the wafer W every shot region SH. Next, the ultraviolet irradiation unit  3  irradiates the imprinting material with ultraviolet light with the template TM pressed on the imprinting material to cure the imprinting material, and then the above processing is repeated from one of the shot regions SH to another, whereby imprinting patterns can be formed on the entire pattern forming region R 2  of the wafer W. 
     In that case, however, at the perimeter of the pattern forming region R 2 , imperfect shots result. At the imperfect shots, only part of the four transfer regions T 1  to T 4  of the template TM is used. That is, at the imperfect shots, certain regions of the transfer regions T 1  to T 4  are frequently used, and thus the number of the transfer performed using the transfer regions T 1  to T 4  becomes unbalanced. 
     For example, since there are only two chip regions at shot regions SA and SC, imperfect shots result. In the case where it is assumed that at that time, the transfer to the shot regions SA and SC has been repeated using the transfer regions T 2  and T 4  of the template TM along an arrow on the wafer W, the number of the transfer performed using the transfer regions T 1  and T 3  of the template TM comes to 59 times, and the number of the transfer performed using the transfer regions T 2  and T 4  of the template TM comes to 62 times. 
     When the number of the transfer performed using the transfer regions T 1  to T 4  has become unbalanced like the above, the possibility of occurrence of breakage and defects increases at the transfer regions T 2  and T 4  with which the transfer has been frequently performed. And further, in the case where breakage and defects have been caused even at part of the transfer regions T 1  to T 4 , the use of the entire template TM becomes impossible. 
     On the other hand, in the case where it is assumed that pattern transfer to the shot region SA has been performed using the transfer regions T 1  and T 3  of the template TM and pattern transfer to the shot region SC has been performed using the transfer regions T 2  and T 4  of the template TM, the number of the transfer performed using the transfer regions T 1  and T 3  of the template TM comes to 60 times, and the number of the transfer performed using the transfer regions T 2  and T 4  of the template TM comes to 61 times. 
     Therefore, when compared with the case where the transfer to the shot regions SA and SC has been performed using the transfer regions T 2  and T 4  of the template TM, the number of the transfer performed using the transfer regions T 1  to T 4  of the template TM are evened out, and thus the number of the transfer performed using the transfer regions T 2  and T 4  decreases. Hence it becomes possible to prevent breakage and defects from readily occurring at the transfer regions T 2  and T 4  of the template TM, and the life of the template TM can, therefore, be lengthened. 
     However, in the case where pattern transfer to the shot region SA has been performed using the transfer regions T 1  and T 3  of the template TM as described above, the transfer regions T 2  and T 4  of the template TM overlap into the shot region SB; therefore, in the case where pattern transfer to the shot region SB has already been performed, the shot region SB as a transfer-performed region collides with the transfer regions T 2  and T 4  of the template TM, and thus an imprinting pattern formed at the transfer-performed shot region SB is damaged. 
     Hence the order of pattern transfer to the shot region SA is set so that the transfer to the shot region SA is performed before the transfer to the shot region SB is performed. 
       FIGS. 3A and 3B  are cross-sectional views illustrating an imprinting method employed at the shot region SA of  FIG. 2A . 
     As illustrated in  FIG. 3A , the shot region SB adjoins the shot region SA. To begin with, an imprinting material  12 A′ is delivered through the nozzle  4  onto the shot region SA of the wafer W by using a method such as an inkjet method. Incidentally, as the imprinting material  12 A′, an ultraviolet cure resist, for example, can be used. 
     Next, as illustrated in  FIG. 3B , the template TM is pressed on the imprinting material  12 A′ to form an imprinting pattern  12 A on the wafer W. Incidentally, the template TM can be made of quartz, for example. In this embodiment, in the template TM are formed concave portions K corresponding to the imprinting pattern  12 A; that is, by pressing the template TM on the imprinting material  12 A′, the imprinting material  12 A′ is sucked up into the concave portions K by a capillary phenomenon, whereby the imprinting pattern  12 A corresponding to the shape of the concave portions K is formed. 
     Thereafter, by irradiating the imprinting pattern  12 A with ultraviolet light through the template TM with the template TM pressed on the imprinting pattern  12 A, the imprinting pattern  12 A cures. 
     In the example of  FIG. 3B , an ultraviolet cure resist may be used as the imprinting material  12 A′ to cure the imprinting pattern  12 A, but a thermosetting resist may be used. 
     When forming the imprinting pattern  12 A at the shot region SA, the transfer regions T 1  and T 3  of the template TM can be pressed on the imprinting material  12 A′. And further, before forming an imprinting pattern  12 B (see  FIG. 5B ) at the shot region SB, the imprinting pattern  12 A can be formed at the shot region SA. Therefore, in the case where the transfer regions T 2  and T 4  of the template TM also overlap into the shot region SB when forming the imprinting pattern  12 A at the shot region SA, it is possible to prevent the imprinting pattern  12 B at the shot region SB from being damaged. 
       FIGS. 4A and 4B  are cross-sectional views illustrating an imprinting method employed at the shot region SC of  FIG. 2A . 
     As illustrated in  FIG. 4A , the shot region SD adjoins the shot region SC. To begin with, an imprinting material  12 C′ is delivered through the nozzle  4  onto the shot region SC of the wafer W by using a method such as an inkjet method. 
     Next, as illustrated in  FIG. 4B , by pressing the template TM on the imprinting material  12 C′, an imprinting pattern  12 C is formed on the wafer W. 
     Thereafter, by irradiating the imprinting pattern  12 C with ultraviolet light through the template TM with the template TM pressed on the imprinting pattern  12 C, the imprinting pattern  12 C cures. 
     When forming the imprinting pattern  12 C at the shot region SC, the transfer regions T 2  and T 4  of the template TM can be pressed on the imprinting material  12 C′. Therefore, at the shot region SA, the transfer regions T 1  and T 3  of the template TM can be used; at the shot region SC, the transfer regions T 2  and T 4  of the template TM can be used. Thus, in the case where imperfect shots result at the shot regions SA and SC too, the number of the transfer performed using the shot regions T 1  to T 4  of the template TM can be evened out, whereby the life of the template TM can be lengthened. 
       FIGS. 5A and 5B  are cross-sectional views illustrating an imprinting method employed at the shot region SB of  FIG. 2A . 
     As illustrated in  FIG. 5A , an imprinting material  12 B′ is delivered through the nozzle  4  onto the shot region SB by using a method such as an inkjet method. 
     Next, as illustrated in  FIG. 5B , the template TM is pressed on the imprinting material  12 B′ to form an imprinting pattern  12 B on the wafer W. 
     Thereafter, by irradiating the imprinting pattern  12 B with ultraviolet light through the template TM with the template TM pressed on the imprinting pattern  12 B, the imprinting pattern  12 B cures. 
     In this case, by forming the imprinting pattern  12 B at the shot region SB after the formation of the imprinting pattern  12 A at the shot region SA, it is possible to prevent the imprinting pattern  12 B at the shot region SB from being damaged. 
     After the formation of the imprinting patterns at all the shot regions SH of the wafer W, the wafer W is processed via the imprinting patterns, whereby semiconductor devices can be made on the wafer W. Incidentally, as a method for processing the wafer W, etching processing may be performed, or ion implantation processing may be performed. 
     Although the case where the template TM is provided with the four transfer regions T 1  to T 4  has been taken as an example in this embodiment, the template TM can be provided with N transfer regions. And further, although the case where the transfer regions T 1  to T 4  correspond respectively to the chip regions C 1  to C 4  of the wafer W has been taken as an example in  FIGS. 2A and 2B , the transfer regions T 1  to T 4  may correspond to circuit blocks and so on. Furthermore, although the case where the wafer W is used as an underlying layer for the imprinting pattern formation has been described as an example in the first embodiment, a conductive layer or an insulating layer may be formed on the wafer W as the underlying layer for the imprinting pattern formation. 
     Second Embodiment 
     In the first embodiment has been described the method in which pattern transfer to the shot region SA is performed using the transfer regions T 1  and T 3  of the template TM, and pattern transfer to the shot region SC is performed using the transfer regions T 2  and T 4  of the template TM; however even in this method, the number of the transfer performed using the transfer regions T 1  and T 3  of the template TM comes to 60 times, and the number of the transfer performed using the transfer regions T 2  and T 4  of the template TM comes to 61 times, that is, there is a difference in the number of the transfer between the transfer regions T 1  and T 3  and the transfer regions T 2  and T 4 . 
     On the other hand, at a first wafer W used in a second embodiment, pattern transfer to the shot region SA is performed using the transfer regions T 1  and T 3  of the template TM, and pattern transfer to the shot region SC is performed using the transfer regions T 2  and T 4  of the template TM. Then, at a second wafer W, pattern transfer to the shot regions SA and SC can be performed using the transfer regions T 1  and T 3  of the template TM. 
     In that case, at the first wafer W, the number of the transfer performed using the transfer regions T 1  and T 3  of the template TM comes to 60 times, and the number of the transfer performed using the transfer regions T 2  and T 4  of the template TM comes to 61 times. At the second wafer W, the number of the transfer performed using the transfer regions T 1  and T 3  of the template TM comes to 61 times, and the number of the transfer performed using the transfer regions T 2  and T 4  of the template TM comes to 60 times. Therefore, at the two wafers W, the total number of the transfer performed using the transfer regions T 1  to T 4  of the template TM comes to 121 times, and thus a correspondence is seen between the number of the transfer performed using the transfer regions T 1  and T 3  and the number of the transfer performed using the transfer regions T 2  and T 4 . That is, by selecting the transfer regions T 1  to T 4  such that the number of pattern transfer performed using the transfer regions T 1  to T 4  is evened out with respect to the M wafers W (M is a positive integer), the correspondence between the number of the transfer performed using the transfer regions T 1  to T 4  can be implemented. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.