1. Field of the Invention
The present invention relates to an imprint apparatus for pressing resin on a shot region on a substrate and a mold to each other to form a resin pattern on the shot region.
2. Description of the Related Art
There is known nanoimprinting, which is a technique replacing a method of forming fine patterns of semiconductor devices and micro electro-mechanical systems (MEMS) by photolithography using ultraviolet rays, X-rays, and electron beams. In the nanoimprinting, a mold (also referred to as a template or original) having fine patterns formed by exposure with an electron beam is pressed against (imprinted onto) a substrate, such as a wafer, coated with a resin material to transfer the patterns to the resin.
There are several types of nanoimprinting, and one of those is a photo-curing method (U.S. Pat. No. 7,027,156). In the photo-curing method, a transparent mold is pressed against a UV-curable resin, and the mold is separated (released) after the resin is exposed and cured. The nanoimprinting using the photo-curing method is suitable for the manufacture of semiconductor integrated circuits because the temperature control is relatively easy and an alignment mark on the substrate can be observed through the transparent mold.
Although there is a method in which a pattern is transferred to the entire surface of the substrate at a time, taking into consideration the case where different patterns are superposed, a step-and-repeat method is to be employed, in which a mold having substantially the same size as the chip of the device to be manufactured is fabricated and the pattern thereon is successively transferred to the shot regions on the substrate.
In addition, a suitable one of a die-by-die method is used, in which the alignment is performed on each shot region, and a global alignment method, depending on the alignment accuracy of the shot regions and the throughput.
In such a nanoimprint apparatus, resin is coated on a substrate using a dispenser head, which is a discharge unit for discharging a UV-curable resin (hereinafter, “resin”).
The dispenser head has discharging nozzles that are linearly arranged over a length greater than the width of a shot region, and discharges resin onto each shot region on the substrate, while scanning a substrate stage carrying a substrate.
Alternatively, resin is coated on a substrate using a dispenser head having discharging nozzles arranged in a matrix and capable of discharging the resin at a time onto the entirety of a shot region, after the substrate stage carrying the substrate is moved to bring the target shot region beneath the dispenser head.
Accordingly, in order to coat all shot regions on the substrate with resin, the substrate stage (X-Y stage) is to have a stroke equivalent to at least the outer diameter of the substrate.
On the other hand, if pattern transfer is performed using the global alignment method, after the mold is installed on a mold chuck serving as a mold holding unit or mold holder, moving directions of the substrate stage (two orthogonal axes) are aligned with the two orthogonal axes, which serve as the reference on the surface of the mold having the pattern.
At this time, using a reference mark on the substrate stage and an alignment mark on the mold, the direction of the mold (directions of the aforementioned two axes) is adjusted.
Thus, the stroke over which the substrate stage is driven to bring the reference mark on the substrate stage beneath a plurality of alignment marks of the mold is to be considered.
The stroke may be too large depending on the arrangement of the dispenser and the arrangement of the reference mark on the X-Y stage. Such a large stroke may be disadvantageous in footprint of the imprint apparatus.
The present invention provides an apparatus for pressing resin on a shot region of a substrate and a mold to each other to form a resin pattern on the shot region, the apparatus including: a mold chuck; an X-Y stage including a substrate chuck, the resin held by the substrate chuck and the mold held by the mold chuck being pressed to each other in a Z-axis direction; a dispenser configured to dispense the resin on the shot region; a scope configured to measure, in an X-Y plane, a position of a substrate mark formed in each of a plurality of shot regions of the substrate held by the substrate chuck; and a reference mark formed on the X-Y stage, wherein the X-Y stage has a moving range allowing the dispenser to dispense the resin on all shot regions of the substrate, and the reference mark is arranged at a position on the X-Y stage where the position of the reference mark can be measured within the moving range of the X-Y stage.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
Referring to the attached drawings, a nanoimprint apparatus (imprint apparatus) using a photo-curing method according to embodiments of the present invention will be described.
The XY stage 4 is placed on a base 5. A reference mirror 6 attached to the fine-motion stage 3 reflects light from a laser interferometer 7 to measure the position of the fine-motion stage 3 in the x and y directions (y direction is not shown). Posts 8 and 8′ standing upright on the base 5 support a top board 9.
A mold 10 has, on the surface thereof, a protruding and recessed pattern P2 to be transferred to the wafer 1, and is fixed to a mold chuck 11 by a mechanical holding unit (not shown). Similarly, the mold chuck 11 is placed on a mold stage 12 by a mechanical holding unit (not shown). A plurality of positioning pins 11P restrict the position of the mold 10 on the mold chuck 11, when the mold 10 is installed on the mold chuck 11.
The mold stage 12 has a function for correcting the position in the θ (rotation about the Z-axis) direction of the mold 10 (mold chuck 11) and a tilt function for correcting the inclination of the mold 10. The mold stage 12 has a reflection surface for reflecting light from the laser interferometer 7′ in order to measure the position in the x and y directions (y direction is not shown) thereof. The mold chuck 11 and the mold stage 12 have openings 11H and 12H, respectively, that allow UV rays emitted from a UV light source 16 and passing through a collimating lens 17 to reach the mold 10 and irradiate resin on the wafer 1.
Guide bars 14 and 14′ penetrating the top board 9 are fixed to the mold stage 12 at one end and to a guide bar plate 13 at the other end. Linear actuators 15 and 15′ formed of air cylinders or linear motors drive the guide bars 14 and 14′ in the Z-axis direction in
An alignment shelf 18 is supported between posts 19 and 19′ so as to be hung from the top board 9, and the guide bars 14 and 14′ penetrate the alignment shelf 18. A gap sensor 20, which is a capacitance sensor or the like, measures the height (flatness) of the wafer 1 on the wafer chuck 2. A plurality of load cells 21 (not shown in
Through-the-mold (TTM) alignment scopes 30 and 30′ are used to measure the alignment. These scopes 30 and 30′ include an optical system and an image-pickup system or a photodetector for measuring the positional deviation between an alignment mark formed on the wafer 1 (also referred to as a substrate mark) and an alignment mark formed on the mold (also referred to as a mold mark). Using the TTM alignment scopes 30 and 30′, the positional deviations in the x and y directions between the wafer 1 and the mold 10 are measured.
A dispenser head (resin discharge unit) 32 has resin drop nozzles for dropping liquid resin on the surface of the wafer 1. The liquid resin may be a photocuring resin.
A reference mark 50 is provided on a reference mark mount disposed on the fine-motion stage 3 (X-Y stage).
A central processing unit (CPU) 100 controls the foregoing actuators and sensors and makes the imprint apparatus perform a predetermined operation.
Referring to
In
In step S2, by simultaneously observing alignment marks M1 and M2 on the mold 10, which are shown in
Then, according to the result of measurement, the mold stage 12 mainly corrects the position of the mold 10 in the θ (rotation about the Z-axis) direction.
Next, in step S3, the wafer 1 is supplied to the wafer chuck 2 by a wafer conveying device (not shown).
In step S4, the XY stage 4 is driven and the height (flatness) of the entire surface of the wafer 1 is measured with the gap sensor 20. As will be described below, this measurement data will be used when the shot surface of the wafer 1 is aligned with the reference plane of the apparatus (not shown) before imprinting.
In step S5, images of a plurality of pre-alignment marks (not shown) previously transferred to the wafer 1 are captured by a pre-alignment measurement device (not shown). Then, the deviation of the plurality of pre-alignment marks in the x and y directions with respect to the apparatus is measured through image processing, and the position of the wafer 1 in the θ (rotation about the Z-axis) direction is corrected according to the result.
In step S6, measurement using the TTM alignment scopes 30 and 30′ is performed. That is, in sample measurement shot regions, the relative positional deviation in the x and y directions (the positional deviation in the xy plane) between the alignment marks M1 and M2 on the mold (mold marks) and the alignment marks W1 and W2 on the wafer 1 (substrate marks) is measured. The hatched shot regions 2, 9, 13, and 20 in
In
From these positional deviations in the x and y directions, the positional deviation in the θ (rotation about the Z-axis) direction is calculated.
Then, from the result of measurement with the TTM alignment scopes 30 and 30′ in the sample measurement shot regions in
This is the same method as the global alignment measurement method used in a semiconductor projection exposure apparatus using a step-and-repeat method, which is disclosed in, for example, Japanese Patent No. 03548428.
Next, in step S7, the pattern is transferred to each shot region on the wafer 1, as shown in the flowchart in
When the pattern has been transferred to all shot regions, in step S8, a wafer conveying device (not shown) recovers the wafer 1 from the wafer chuck 2.
In step S9, whether there is a subsequent wafer to be subjected to the pattern transfer is determined. If there is such a wafer (No in step S9), the process returns to step S3, and if there is no such wafer (YES in step S9), the process proceeds to step S10.
In step S10, the mold conveying device (not shown) recovers the mold 10 from the mold chuck 11, thus completing the pattern transfer to the plurality of wafers.
Referring to
In
In step S702 (drop photocuring resin), a photocuring resin is dropped onto the target shot region on the wafer 1 with the dispenser head 32.
In the case where the dispenser head 32 has linearly arranged resin discharging nozzles, the resin is discharged while the XY stage 4 is driven in accordance with the size of the shot region.
On the other hand, in the case where the resin discharging nozzles are arranged in a matrix covering the entire surface of the shot region, the XY stage 4 is not to be driven, and the resin can be discharged at a time.
Then, in step S703 (drive wafer stage), the XY stage 4 is driven so as to bring the surface of the shot region to a position facing the pattern P2 on the mold 10. At this time, the position of the wafer stage is determined according to the result of the alignment measurement in step S6 in
Furthermore, the inclination and the height in the z direction of the wafer chuck 2 are adjusted by the fine-motion stage 3 in accordance with the measurement data of the height of the wafer, and the surface of the shot region of the wafer 1 is aligned with the reference plane (not shown) of the apparatus.
In step S704, the linear actuators 15 and 15′ are driven to lower the mold chuck 11 to a predetermined position.
In step S705, whether the pressing force of the mold 10 is appropriate is determined from the output of the plurality of load cells 21 (not shown) attached to the mold chuck 11 or the mold stage 12. If the pressing force is not within a predetermined range (No in step S705), the process proceeds to S706.
In step S706 (adjust positions of mold or wafer), the pressing force of the mold 10 is adjusted either by changing the position of the mold chuck 11 in the z direction by the linear actuators 15 and 15′ or by changing the position of the wafer chuck 2 in the z direction by the fine-motion stage 3. Steps S705 and S706 are repeated until the intended pressing force is achieved. When the pressing force of the mold 10 is determined to be appropriate in step S705 (YES in step S705), the process proceeds to S707.
In step S707, the UV light source 16 irradiates UV rays for a predetermined period of time.
When the irradiation of the UV rays is completed, in step S708, the linear actuators 15 and 15′ are driven to raise the mold chuck 11, and the mold 10 is separated from the cured resin on the wafer 1.
In step S709, the XY stage 4 is driven to move the wafer 1 and bring the next shot region beneath the dispenser head 32.
In step S710, whether the pattern has been transferred to all shot regions on the wafer 1 is determined.
If there are shot regions to which the pattern has not been transferred (NO in step S710), the process returns to step S702.
If there are no shot regions to which the pattern has not been transferred (YES in step S710), the process proceeds to step S711.
In step S711 (drive wafer stage), the XY stage 4 is moved to a predetermined position for recovery of the wafer (step S8 in
Although the operation of transferring the pattern to the wafer 1 has been described above with reference to
In this case, the die-by-die alignment is performed before or after step S704 in
In
As can be seen from
As can be seen from
As has been described, when the center of the mold chuck 11 and the center of the wafer chuck 2 are aligned in the xy plane, the reference mark 50 is disposed on the same side as the mold chuck 11 with respect to the dispenser head 32, on the fine-motion stage 3.
As shown in
If it is only to make the stroke of the XY stage 4 smaller than the stroke L2 in
The center of the dispenser means the center of the resin discharge ports provided in the dispenser opposite the substrate, and the resin discharge ports form, for example, a linear or rectangular area having multiple openings (holes). Typically, the projection of the mold chuck 11 on the xy plane is rectangular, and the center of the mold chuck 11 means the center of the rectangular shape. Typically, the projection of the substrate chuck on the xy plane is circular, and the center of the substrate chuck means the center of the circular shape. Typically, the reference mark 50 has a shape consisting of a collection of rectangular mark elements, and the center of the reference mark 50 means the center of the shape.
Because an increase in the stroke of the X-Y stage for the mold alignment measurement (reference mark measurement) for the global alignment measurement can be reduced, a small nanoimprint apparatus with a small footprint can be provided.
Referring to
In
The arrangement of
Referring to
In
In
The arrangement of
Referring to
Even in the case where the plurality of dispenser heads are arranged as in
According to the above-described embodiments, it is possible to provide an imprint apparatus having a reduced stroke of the substrate stage (X-Y stage). In addition, it is possible to provide an imprint apparatus with a small footprint and capable of performing global alignment.
A method of manufacturing devices, serving as articles, such as semiconductor integrated circuit elements, liquid crystal display elements, etc., may include a step of transferring (forming) a pattern to a substrate, such as a wafer, a glass plate, a film-like substrate, or the like, using the above-described imprint apparatus, and a step of etching the substrate. When manufacturing other articles, such as patterned media (recording media) and optical elements, a step of processing the substrate may be performed instead of the etching step.
The present invention is industrially applicable in forming fine patterns for manufacturing, for example, the aforementioned articles.
While various embodiments of the present invention have been described above, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. Any modification or variation within the scope of the invention should be possible.
This application claims the benefit of Japanese Patent Application No. 2008-246332 filed Sep. 25, 2008, which is hereby incorporated by reference herein in its entirety.
Number | Date | Country | Kind |
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2008-246332 | Sep 2008 | JP | national |