Patent Publication Number: US-2015072445-A1

Title: Lithography apparatus and method of manufacturing article

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a lithography apparatus and a method of manufacturing an article. 
     2. Description of the Related Art 
     In the manufacture of a semiconductor device, the need for refining the line width is becoming stricter year by year. One of production apparatuses which obtains a resolution with a line width of 10 nm or less is an electron beam lithography apparatus. In particular, a multi-electron beam lithography apparatus which writes patterns simultaneously with a plurality of electron beams without using any mask has been proposed (Japanese Patent Laid-Open No. 2011-513905). The multi-electron beam lithography apparatus has many advantages, toward practical applications, that it eliminates the need for a mask which is one factor of manufacturing cost, and it can control each electron beam in a programmable manner and is, thus suitable for manufacturing a variety of devices in small quantities, and the like. 
     In general, however, the electron beam lithography takes writing time about ten times or more for the same field size as compared to optical lithography and is thus poor in a throughput. To cope with this, Japanese Patent Laid-Open No. 2012-518902 discloses an arrangement which improves a throughput by arranging a plurality of clusters each of which is comprised of an electron beam lithography apparatus. 
     A conventional cluster type electron beam lithography apparatus has one chamber in one cluster, and includes, inside the chamber, one substrate moving stage and one electron beam column unit. Accordingly, the cluster type electron beam lithography apparatus processes one substrate per cluster. Since a space where an actuator of a moving stage is arranged and a space for a chamber wall are redundant, substrate processing throughput efficiency per footprint is poor even if clustering is performed. 
     SUMMARY OF THE INVENTION 
     The present invention provides, for example, a lithography apparatus which improves a substrate processing throughput per footprint. 
     According to one aspect of the present invention, a lithography apparatus which performs writing on a substrate using a charged particle beam, comprises a plurality of column units each of which comprises a charged particle optical system, a plurality of stages each of which is movable while holding the substrate, and a controller configured to move the plurality of stages in synchronization with each other in a positional relationship corresponding to an arrangement of the plurality of column units, and perform writing on a plurality of substrates held in the plurality of stages simultaneously. 
     Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view showing the arrangement of a lithography apparatus according to the first embodiment; 
         FIG. 2  is a view showing the arrangement of a lithography apparatus according to the second embodiment; 
         FIG. 3  is a view showing the arrangement of a lithography apparatus according to the third embodiment; 
         FIG. 4  is a view showing the arrangement of a lithography apparatus according to a modification of the third embodiment; 
         FIG. 5  is a view showing the arrangement of a lithography apparatus according to the fourth embodiment; 
         FIG. 6  is a view showing the arrangement of a lithography apparatus according to the fifth embodiment; 
         FIG. 7  is a view showing the arrangement of a lithography apparatus according to the sixth embodiment; 
         FIG. 8  is a view showing the arrangement of a lithography apparatus according to the seventh embodiment; and 
         FIG. 9  is a view showing the arrangement of a lithography apparatus according to the eighth embodiment. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Various exemplary embodiments, features, and aspects of the invention will be described in detail below with reference to the drawings. 
     Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Note that the following embodiments are not intended to limit the present invention and are merely concrete examples advantageous in practicing the invention. Also, not all combinations of features to be described in the embodiments are indispensable for the means to solve the problems according to the present invention. 
     First Embodiment  
       FIG. 1  is a plan view showing the arrangement of a lithography apparatus according to the first embodiment. A lithography apparatus  10  according to this embodiment is, for example, a writing apparatus which performs writing on a substrate using a charged particle beam. The substrate is, for example, a silicon wafer or a glass substrate. The lithography apparatus  10  has a vacuum chamber  11 . A plurality of column units each of which comprises a charged particle optical system are located inside this vacuum chamber  11 . In this embodiment, for example, two column units  12  are arranged. In addition, a plurality of stages movable in the x and y directions while holding substrates  13  are located in the vacuum chamber  11 . In this embodiment, for example, two stages  14  are located. A controller  15  performs control of the charged particle optical systems in the column units  12  and control of respective components including the stages  14 . 
     The vacuum chamber  11  is necessary to maintain stability of charged particles till they are irradiated after they were generated. Each column unit  12  is contained and fixed in the vacuum chamber  11 , and can irradiate a predetermined position with the charged particles. In this embodiment, the plurality of column units are arranged to process a plurality of substrates simultaneously and in parallel. Furthermore, it is desirable that charged particle columns inside the column units can irradiate the position with as many charged particles as possible at once. Hence, it is desirable that one column unit includes a plurality of columns each of which includes a charged particle optical system comprised of an electron gun, lenses, deflectors, and the like, so that a number of electron beams can be irradiated simultaneously. The concrete examples thereof will be described later in the fourth and the fifth embodiments. 
     Irradiation positions need to be changed to irradiate the entire surfaces of the substrates. This function can be implemented by positioning the substrates directly under the corresponding column units by the corresponding stages. In this embodiment, in particular, the column units are used for the respective substrates, and the plurality of column units are fixed. The controller  15  causes the stages  14  to move while keeping the relative distance (indicated by an alternate long and short dashed line R in  FIG. 1 ) of the substrates  13  almost constant. This allows the plurality of stages  14  to move in synchronization with each other in a positional relationship corresponding to the arrangement of the plurality of column units  12 . This makes it possible to perform writing on the substrates  13  held in the stages  14  simultaneously and in parallel. As a consequence, the moving distance of each substrate and the relative distance between the plurality of substrates can be minimized within the necessary range, thereby improving a substrate processing throughput per footprint. 
     Second Embodiment  
     A lithography apparatus according to the second embodiment will now be described with reference to  FIG. 2 . In the present invention, a plurality of substrates are processed simultaneously, thus requiring high overlay accuracy for all the substrates equally. In order to meet the requirement, the apparatus according to this embodiment measures the positions of all the substrates or the positions of substrate holders of all stages by a measurement unit arranged in a predetermined position. This arrangement makes it possible to accurately measure irradiation positional errors from target values for all the substrates. Furthermore, each column unit can control a beam position. Beam position control is possible by, for example, a deflector or a pattern (a pattern data) change. If the irradiation positional error falls within the range of this beam position control, it can be corrected by beam position control based on the measurement value of the error. 
       FIG. 2  shows an example in which two substrates are processed simultaneously. In this embodiment, two fine moving stages  22  are mounted on a coarse moving stage  21  which is movable in the x and y directions. Substrates  13  are held on the respective fine moving stages. Each laser interferometer  23  which serves as a measurement unit fixed in a predetermined position of a vacuum chamber  11  can measure the side position of each fine moving stage by the reflected light from measurement light M, and measure the translation positions x and y, and an angle θz about a z-axis of each substrate. Note that in  FIG. 2 , column units  12 , the coarse moving stage  21 , the fine moving stages  22 , and the laser interferometers  23  can be controlled by a controller  15  as in the first embodiment, and the illustration thereof is omitted (the same shall apply hereinafter). 
     A position measurement principle is based not only on the laser interferometer but also on a laser displacement sensor, a capacitive sensor, an encoder, a magnetostrictive sensor or a combination thereof. 
     Third Embodiment  
     A lithography apparatus according to the third embodiment will now be described with reference to  FIG. 3 . In this embodiment, a plurality of column units are arranged so that two or less column units are arranged on the same line in a planar view. This arrangement makes it possible to measure a position in the x and y directions from a fixed position for each substrate even in an arrangement where three or more substrates are handled. Footprint efficiency can also be improved. 
     In the example of  FIG. 3 , three column units  12  are arranged at the respective vertex positions of a triangle in the planar view. An alternate long and short dashed line P in  FIG. 3  represents this triangle. Three fine moving stages  22  are arranged on a coarse moving stage  21  in positions corresponding to this column unit arrangement. This makes it possible to move the plurality of fine moving stages in synchronization with each other in a positional relationship corresponding to the column unit arrangement, and perform writing on substrates  13  held in the respective fine moving stages simultaneously. 
     The position y and the rotation θz of each fine moving stage can be measured by each laser interferometer  23  fixed to a vacuum chamber  11 . Furthermore, a laser interferometer  31  fixed to each fine moving stage measures bar mirrors  32  fixed to the vacuum chamber  11 . This makes it possible to measure a position x of each fine moving stage. 
     In the example of  FIG. 4 , four column units  12  are arranged at the respective vertex positions of a rectangle in the planar view. An alternate long and short dashed line in  FIG. 4  represents this rectangle. Four fine moving stages  22  are arranged on the coarse moving stage  21  in positions corresponding to this column unit arrangement. This makes it possible to move the plurality of fine moving stages in synchronization with each other in a positional relationship corresponding to the column unit arrangement, and perform writing on the substrates  13  held in the respective fine moving stages simultaneously. 
     The position y and the rotation θz of each fine moving stage can be measured by each laser interferometer  23  fixed to the vacuum chamber  11 . Furthermore, the laser interferometer  31  fixed to each fine moving stage measures the bar mirrors  32  fixed to the vacuum chamber  11 . This makes it possible to measure the position x of each fine moving stage. 
     Fourth Embodiment  
     A lithography apparatus according to the fourth embodiment will now be described with reference to  FIG. 5 . In this embodiment, each column unit includes a plurality of columns. Each column includes a charged particle optical system comprised of an electron gun, lenses, deflectors, and the like. A controller  15  controls electron beams from the respective columns independently. This makes it possible to irradiate one substrate with the plurality of electron beams. In the example of  FIG. 5 , each column unit  12  includes two columns  12   a  and  12   b.  The arrayed direction of the columns  12   a  and  12   b  is parallel to that of two column units. More specifically, two column units are arranged in the x-axis direction, and two columns within each column unit are also arranged in the x-axis direction. At this time, scanning for writing is performed in the y-axis direction. As shown in  FIG. 5 , stripe-shaped patterns W are transferred to substrates  13 , and then two substrates are moved step by step in the x direction to transfer next patterns to the substrate. By repeating these steps, the patterns can be transferred to the entire surfaces of the substrates. A scanning direction S for writing is defined by a column array. Therefore, setting the column array and a substrate array to be parallel to each other eliminates a wasteful moving distance. This makes it possible to minimize a relative distance between the substrates. This embodiment is advantageous in a mode in which the arrayed direction of the columns is oblique to the arrayed direction of the column units (that is, the arrayed direction of the substrates). 
     Fifth Embodiment  
     A lithography apparatus according to the fifth embodiment will now be described with reference to  FIG. 6 . In the example of  FIG. 6 , each column unit  12  includes two columns  12   a  and  12   b.  The arrayed direction of the columns  12   a  and  12   b  is perpendicular to that of two column units. More specifically, while two column units are arranged in the y-axis direction, two columns within each column unit are arranged in the x-axis direction. At this time, scanning for writing is performed in the y-axis direction. As shown in  FIG. 6 , stripe-shaped patterns W are transferred to substrates  13 , and then two substrates are moved step by step in the x direction to transfer next patterns to the substrate. By repeating these steps, the patterns can be transferred to the entire surfaces of the substrates. Also in this way, a relative distance between the substrates can be minimized. This embodiment is also advantageous in a mode in which the arrayed direction of the columns is oblique to the arrayed direction of the column units (that is, the arrayed direction of the substrates). 
     Sixth Embodiment  
     A lithography apparatus according to the sixth embodiment will now be described with reference to  FIG. 7 . In this embodiment, a substrate conveyance unit  70  is arranged outside a vacuum chamber  11 . The substrate conveyance unit  70  is a unit for loading or unloading substrates  13  to or from the vacuum chamber  11 . The substrate conveyance unit  70  has substrate conveyance hands  71  for holding and conveying the substrates  13 . The substrate conveyance hands  71  are movable in a direction H perpendicular to the arrayed direction of column units (that is, the arrayed direction of the substrates) when conveying the substrates. This makes it possible to minimize the moving distances of stages  14  and the substrate conveyance hands  71 , thereby improving footprint efficiency. 
     Seventh Embodiment  
     A lithography apparatus according to the seventh embodiment will now be described with reference to  FIG. 8 . In this embodiment, a fine moving stage  22  mounted for each substrate on a coarse moving stage  21  has a mechanism which positions with at least one degree of freedom. Since the plurality of substrates are processed in the present invention, a substrate holding step is required for each substrate. Therefore, positions x and y, and an angle θz about a z-axis of each substrate change between the substrates depending on the precision of a substrate conveyance hand. When errors of these x, y, and θz exceed the range of beam position control, a fine moving positioning mechanism can correct them. It is particularly desirable to feedback a value which is obtained by a position measurement mechanism configured for each substrate, and to perform position control. 
     Also, the thickness unevenness and the flatness of the substrate change between the substrates. These can be pattern errors. Hence, it is desirable to have degrees of freedom to correct a position z, and rotation angles θx and θy. 
     In the example of  FIG. 8 , two x-direction actuators  81  and two y-direction actuators  82  can move the fine moving stages  22  in the x, y, and θz directions. Furthermore, four z-direction actuators  83  can move the fine moving stages  22  in the z, θx, and θy directions. 
     Eighth Embodiment  
     A lithography system according to the eighth embodiment will now be described with reference to  FIG. 9 . The lithography system according to this embodiment sets a lithography apparatus in any of the above-described embodiments as one cluster, and includes a plurality of such clusters. Also in this arrangement, since a substrate moving distance of each cluster is minimized, a total substrate processing throughput can be improved. In addition, since one cluster processes a plurality of substrates, a space for an actuator required in a stage as well as a redundant space by a chamber wall can be reduced, as compared to a conventional arrangement where one cluster processes one substrate. 
     In the example of  FIG. 9 , four clusters  90  are arranged, and one common substrate transport system  95  is arranged among them. Each cluster arranges two substrates in the x direction and can perform writing processing. The common substrate transport system  95  can transport the substrates in the x direction, and load and unload the substrates in the y direction from each cluster. 
     Embodiment of Article Manufacturing Method  
     An article manufacturing method according to an embodiment of the present invention is suitable for manufacturing an article, for example, a microdevice such as a semiconductor device or an element having a microstructure. The article manufacturing method according to this embodiment includes a step of forming a latent image pattern on a photoresist applied to a substrate using the above-described writing apparatus (step of performing writing on a substrate), and a step of developing the substrate on which the latent image pattern has been formed in the preceding step. This manufacturing method further includes other known steps (oxidation, deposition, vapor deposition, doping, planarization, etching, resist peeling, dicing, bonding, packaging, and the like). The article manufacturing method according to this embodiment is advantageous in at least one of the performance, quality, productivity, and production cost of an article, as compared to a conventional method. 
     While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
     This application claims the benefit of Japanese Patent Application No. 2013-187646, filed Sep. 10, 2013, which is hereby incorporated by reference herein in its entirety.