This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2010-213615, filed on Sep. 24, 2010; the entire contents of which are incorporated herein by reference.
Embodiments described herein relate generally to a droplet dispensing control method, a droplet dispensing control device, and a method of manufacturing semiconductor devices.
In the process of manufacturing semiconductor devices, a photo nanoimprint method which transfers the mold (template) of a master stamp to a transfer substrate (hereinafter referred to as a substrate) is being paid attention as a technique capable of enabling both of formation of micro-patterns of 100 nm or less and mass-production. In the photo nanoimprint method, the mold of a master stamp on which patterns to be transferred are formed is pressed into a photo-curable organic material layer (imprint material) applied onto a substrate. In this state, the imprint material is irradiated with light and cured. In this way, the patterns are transferred to the imprint material.
The imprint material is dispensed by an ink jet method and applied onto the substrate for each shot area. In the photo nanoimprint method, a positional deviation wherein the position of a stage with the substrate mounted thereon deviates from the position at which the template is pressed is likely to occur. Moreover, the position of a nozzle array of an ink jet head is likely to tilt at an angle to the movement direction of the stage. Thus, this also may cause another positional deviation wherein the position (landing position) at which the droplet of the imprint material lands on the substrate deviates from an intended landing position. If the landing position of the imprint material is not appropriate for the shot area, defects or faults in filling of the imprint material and fluctuation in thickness are more likely to occur at the periphery of the shot area where the amount of deviation in the landing position is great. As a result, defects would occur in the formed patterns after processing, which can impair the yield of devices. Therefore, it is desirable to dispense the imprint material so as to land at a proper position.
In general, according to one embodiment, a droplet dispensing control method includes detecting an amount of positional deviation in a rotation direction in a stage plane between a stage mounting a substrate on which an imprint material from an ink jet head lands and a template that is pressed into the imprint material on the substrate, as a template positional deviation amount. The method further includes detecting an amount of positional deviation in a rotation direction in the stage plane between a movement direction of the stage and a nozzle array direction of a plurality of nozzles provided in the ink jet head, as a nozzle positional deviation amount. The method further includes calculating a stage movement direction correction value for correcting the movement direction of the stage and an ejection timing correction value for correcting the ejection timing of the imprint material ejected from the respective nozzles, as a correction value for eliminating the positional deviation of a landing position of the imprint material occurring due to the template positional deviation amount and the nozzle positional deviation amount. The method further includes controlling the movement direction of the stage using the stage movement direction correction value and controlling the ejection timing of the imprint material ejected from the respective nozzles using the ejection timing correction value.
Exemplary embodiments of a droplet dispensing control method, a droplet dispensing control device, and a method of manufacturing semiconductor devices will be explained below in detail with reference to the accompanying drawings. The present invention is not limited to the following embodiments.
The imprint device 100 dispenses droplets of a resist (imprint material) 6 onto a transfer substrate such as a wafer 3 and presses a template 5 onto the wafer 3 to thereby transfer the template pattern to the wafer 3. The imprint device 100 of the present embodiment controls the movement direction of the stage 4 and the ejection timing of the resist 6 so as to correct the amount of positional deviation of the template 5 with respect to the stage 4 and the amount of positional deviation of a nozzle array with respect to the movement direction of the stage 4.
The ink jet head 2 has a plurality of nozzles. The respective nozzles are arranged as a nozzle array at predetermined intervals in a predetermined direction. The ink jet head 2 ejects droplets of the resist 6 through the respective nozzles so as to land (be applied) on the wafer 3. The stage 4 holds the wafer 3 mounted thereon and moves it in the in-plane (XY plane) direction of the wafer 3. The resist 6 is a photo-curable organic material, for example.
The template 5 is a mold of a master stamp and the patterns (semiconductor circuit patterns) to be transferred onto the wafer 3 are formed thereon. The template 5 is pressed onto the wafer 3 on which the resist 6 is dispensed. The light source 7 irradiates the resist 6 filled between the template 5 and the wafer 3 with light such as UV light.
The droplet dispensing control device 1 includes a template positional deviation amount detection unit 11, a nozzle positional deviation amount detection unit 12, a correction value calculation unit 13, an ejection timing control unit 14, and a stage movement direction control unit 15.
The template positional deviation amount detection unit 11 detects the amount of positional deviation (amount of rotational deviation) in the rotation direction in the stage plane between the stage 4 and the template 5 (the wafer 3) as a template positional deviation amount. In other words, the template positional deviation amount detection unit 11 detects the mounting position of the template 5 on the stage 4. Specifically, the template positional deviation amount detection unit 11 detects a template positional deviation amount when the template 5 is contacted (pressed) onto the resist 6 on the wafer 3. The template positional deviation amount detection unit 11 detects the template positional deviation amount by detecting the position of the stage 4 and the mounting position of the template 5, for example. The template positional deviation amount detection unit 11 transmits the detected template positional deviation amount to the correction value calculation unit 13.
The nozzle positional deviation amount detection unit 12 detects the amount of positional deviation of a nozzle array with respect to the movement direction of the stage 4 as a nozzle positional deviation amount. Specifically, the nozzle positional deviation amount detection unit 12 detects a nozzle positional deviation amount between the movement direction (XY-directional movement axis) of the stage 4 and an arrangement direction of the nozzle array as an in-plane deviation amount (rotational deviation amount). For example, when the stage 4 moves in the X-axis direction, and the nozzle array is arranged in the Y-axis direction, the amount of angular deviation (the amount of deviation from 90 degrees) between the movement direction of the stage 4 and the arrangement direction of the nozzle array becomes the nozzle positional deviation amount. The nozzle positional deviation amount detection unit 12 detects the nozzle positional deviation amount by detecting the movement direction of the stage 4 and the arrangement direction of the nozzle array, for example. The nozzle positional deviation amount detection unit 12 transmits the detected nozzle positional deviation amount to the correction value calculation unit 13.
The correction value calculation unit 13 calculates a correction value (stage movement direction correction value) for correcting the movement direction of the stage 4 and a correction value (ejection timing correction value) for correcting the ejection timing of the resist 6 based on the template positional deviation amount and the nozzle positional deviation amount. The correction value calculation unit 13 calculates the stage movement direction correction value and the ejection timing correction value for dispensing droplets of the resist 6 to land at a desired position on the wafer 3. In other words, the correction value calculation unit 13 calculates the stage movement direction correction value and the ejection timing correction value for eliminating the positional deviation of the resist landing position which occurs due to the template positional deviation amount and the nozzle positional deviation amount. The correction value calculation unit 13 transmits the calculated stage movement direction correction value to the stage movement direction control unit 15 and the calculated ejection timing correction value to the ejection timing control unit 14.
The ejection timing control unit 14 controls the ejection timing of the resist 6 ejected from the nozzles. The ejection timing control unit 14 corrects the ejection timing of the resist 6 ejected from the nozzles using the ejection timing correction value. The stage movement direction control unit 15 controls the movement direction of the stage 4. The stage movement direction control unit 15 corrects the movement direction of the stage 4 using the stage movement direction correction value.
Next, the flow of a process of ejecting the resist 6 will be described.
In the present embodiment, for example, a plurality of marks for detecting position is formed on the template 5. Moreover, the template 5 is loaded onto a test wafer in advance. After that, the template positional deviation amount detection unit 11 detects the template positional deviation amount by measuring the positions of the position detection marks. The template positional deviation amount detection unit 11 may detect the template positional deviation amount by detection part of template patterns formed on the template 5. The template positional deviation amount detection unit 11 transmits the detected template positional deviation amount to the correction value calculation unit 13.
The nozzle positional deviation amount detection unit 12 detects the amount of positional deviation of the nozzle array with respect to the movement direction of the stage 4 as the nozzle positional deviation amount (step S20). In other words, the nozzle positional deviation amount detection unit 12 detects a wafer scanning direction and a nozzle array tilt during ink-jetting (resist-ejecting). The nozzle positional deviation amount is a relative positional deviation amount between the movement direction of the stage 4 and the arrangement direction of the nozzle array. The template positional deviation amount may be detected after detecting the nozzle positional deviation amount. Moreover, the nozzle positional deviation amount and the template positional deviation amount may be detected at the same time.
In the present embodiment, droplets of the resist 6 are dispensed from the nozzles so as to land on a test wafer, for example, without correcting the movement direction of the stage 4 and the ejection timing. Moreover, in a state where the test wafer is mounted on the stage 4, the nozzle positional deviation amount detection unit 12 detects the nozzle positional deviation amount by measuring the landing position of the resist 6.
Here, the template positional deviation amount and the nozzle positional deviation amount will be described.
The axes 51 to 53 illustrated in
The axes 52 are the XY axes based on the arrangement position (the pressing position of the template 5) of the wafer 3, and are positionally deviated from the axes 51 by a predetermined rotational amount. This rotational amount corresponds to the template positional deviation amount. A desired resist landing position Px is set to the wafer 3. Since there is a positional deviation between the axes 52 and the axes 51, the resist landing position Px is positionally deviated from the axes 51 by the predetermined rotational amount.
The axes 53 are the XY axes based on the movement direction of the stage 4 with respect to the nozzle array, and are positionally deviated from the axes 51 by a predetermined rotational amount. This rotational amount corresponds to the nozzle positional deviation amount.
In
After the template positional deviation amount and the nozzle positional deviation amount are detected using the test wafer 3 or the like, the test wafer 3 is unloaded from the stage 4. Moreover, a wafer 3 (product wafer or the like) on which actual template patterns are formed is loaded on the stage 4.
The correction value calculation unit 13 calculates a stage movement direction correction value for correcting the movement direction of the stage 4 and an ejection timing correction value for correcting the ejection timing of the resist 6 based on the template positional deviation amount and the nozzle positional deviation amount (step S30). In the ink jet head 2, a plurality of nozzles is arranged in the Y-axis direction at predetermined intervals (nozzle pitches) D. Thus, the correction value calculation unit 13 calculates the ejection timing correction value for each nozzle. The process of calculating the stage movement direction correction value and the ejection timing correction value may be performed before the wafer 3 on which actual template patterns is loaded on the stage 4.
For example, the correction value calculation unit 13 calculates stage movement direction correction values Xc and Yc expressed by Expressions (1) and (2) and an ejection timing correction value X(Dn) illustrated in Expression (3).
Xc=X×θt×cos((1−θt)/2) (1)
Yc=X×sin((1−θt)/2) (2)
X(Dn)=n(θt+θd×D) (3)
Here, X is the movement direction of the stage 4 before correction, and D is the distance between nozzles. Moreover, n is an index of the nozzle and is a natural number. A reference nozzle (a nozzle which is the first one arriving at the resist ejecting position) has an index n=1, and a nozzle which is the M-th one (M is a natural number) arriving at the resist ejecting position has an index n=M. Thus, Dn is the distance (y-coordinate) of the nozzle from the point of origin of the nozzle.
The correction value calculation unit 13 transmits the calculated stage movement direction correction value to the stage movement direction control unit 15 and the calculated ejection timing correction value to the ejection timing control unit 14. The stage movement direction control unit 15 controls the movement direction of the stage 4 while correcting the movement direction of the stage 4 using the stage movement direction correction value. In this case, the ejection timing control unit 14 controls the ejection timing of the resist 6 while controlling the ejection timing using the ejection timing correction value. In other words, the droplets of the resist 6 are ejected while the movement direction of the stage 4 and the ejection timing of the resist 6 are corrected (step S40).
The stage movement direction control unit 15 controls the stage 4 so that the stage 4 is moved in the directions X′ and Y′ expressed by Expressions (4) and (5). Moreover, the ejection timing control unit 14 corrects the ejection timing of the resist 6 based on Expression (3).
X′=X−Xc×X−(X×θt×cos((1−θt)/2)) (4)
Y′=Yc=X×sin((1−θt)/2) (5)
Next, the ejection timing of the resist 6 will be described.
As illustrated in
As illustrated in
In
The stage 4 is moved so that the nozzles 21 to 25 pass over the resist landing positions P31 to P35, respectively. At the position N11, ejection of the resist 6 is not performed since the nozzles 21 to 25 have not arrived at the resist landing positions P31 to P35.
When the relative position of the ink jet head 2 to the stage 4 reaches the position N12, the nozzle 25 arrives at the resist landing position P35, and at this point of time, the droplets of the resist 6 are ejected from the nozzle 25.
When the relative position of the ink jet head 2 to the stage 4 reaches the position N13, the nozzle 24 arrives at the resist landing position P34, and at this point of time, the droplets of the resist 6 are ejected from the nozzle 24.
Subsequently, similarly, the droplets of the resist 6 are ejected from the nozzle 23 at the point in time when the nozzle 23 arrives at the resist landing position P33. Moreover, the droplets of the resist 6 are ejected from the nozzle 22 at the point in time when the nozzle 22 arrives at the resist landing position P32. Furthermore, the droplets of the resist 6 are ejected from the nozzle 21 at the point in time when the nozzle 21 arrives at the resist landing position P31.
When imprinting is performed, the imprint device 100 dispenses the droplets of the resist 6 so as to land at a desired position (an effective area corresponding to one shot area of the template 5) on the wafer 3. Then, the template 5 on which patterns to be transferred are formed is pressed into the resist 6 on the wafer 3. In this way, the resist 6 is filled between the template 5 and the wafer 3. In this state, the resist 6 is irradiated with light emitted from the light source 7, and the resist 6 is cured. After that, the template 5 is removed from the resist 6 (demolding process). In this way, the pattern (shape) of the template 5 is transferred to the resist 6 on the wafer 3.
Subsequently, the lower layer side of the wafer 3 is etched using the pattern transferred resist 6 as a mask. In this way, the real pattern corresponding to the pattern of the template 5 is formed on the wafer 3. When a semiconductor device (a semiconductor integrated circuit) is manufactured, the above-mentioned processes of dispensing the resist 6, curing the resist 6, demolding the template 5, and etching the wafer 3 are repeatedly performed for each layer.
Next, the hardware configuration of the droplet dispensing control device 1 will be described.
The CPU 91 calculates a stage movement direction correction value and an ejection timing correction value using a correction value calculation program 97 which is a computer program. The display unit 94 is a display device such as a liquid crystal monitor and displays a template positional deviation amount, a nozzle positional deviation amount, a stage movement direction correction value, an ejection timing correction value, and the like based on an instruction from the CPU 91. The input unit 95 is configured to include a mouse or a keyboard and receives instruction information (parameters required for calculating the stage movement direction correction value and the ejection timing correction value) input from the user. The instruction information input to the input unit 95 is sent to the CPU 91.
The correction value calculation program 97 is stored in the ROM 92 and is load into the RAM 93 through the bus line.
The CPU 91 executes the correction value calculation program 97 loaded into the RAM 93. Specifically, in the droplet dispensing control device 1, the CPU 91 reads the correction value calculation program 97 from the ROM 92, expands the correction value calculation program 97 in a program storage area within the RAM 93, and executes various processes in response to the instruction from the input unit 95 input by the user. The CPU 91 temporarily stores various data generated during the various processes in the data storage area formed in the RAM 93.
The correction value calculation program 97 executed by the droplet dispensing control device 1 has a modular configuration including the template positional deviation amount detection unit 11, the nozzle positional deviation amount detection unit 12, the correction value calculation unit 13, the ejection timing control unit 14, and the stage movement direction control unit 15, and these units are loaded onto a main storage device and generated on the main storage device.
In the present embodiment, although the droplet dispensing control device 1 is configured to include the template positional deviation amount detection unit 11 and the nozzle positional deviation amount detection unit 12, the template positional deviation amount detection unit 11 may be separated from the droplet dispensing control device 1. Moreover, the nozzle positional deviation amount detection unit 12 may be separated from the droplet dispensing control device 1. Furthermore, the ejection timing control unit 14 may be separated from the droplet dispensing control device 1. Furthermore, the stage movement direction control unit 15 may be separated from the droplet dispensing control device 1.
As above, according to the embodiment, the movement direction of the stage 4 and the ejection timing of the resist 6 are controlled so as to eliminate the positional deviation of the landing position of the imprint material occurring due to the template positional deviation amount and the nozzle positional deviation amount. Thus, it is possible to dispense droplets of the resist 6 so as to land at an appropriate position (intended landing position) on the wafer 3. In this way, it is possible to prevent defects or faults in filling of the resist 6 and fluctuation in thickness. As a result, it is possible to prevent pattern formation defects and to improve the yield ratio of devices.
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.
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