This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2012-030801, filed Feb. 15, 2012; the entire contents of which are incorporated herein by reference.
Embodiments described herein relate generally to an imprinting apparatus and an imprinting method.
Nano-imprinting lithography (NIL) is one of the technologies used in the lithography process in the manufacture of semiconductor devices. NIL is a technology utilizing a template having a three-dimensional embossed pattern comprising a plurality of projections and recesses that may be formed by electron beam (EB) writing or lithography, etc. To form a three dimensional pattern on a substrate, the embossed pattern is pressed against a substrate and thereby transfer a three-dimensional reverse image of the embossed pattern of the template onto the substrate.
NIL is carried out by dropping or otherwise forming a photo-curing resin onto a substrate, such as a wafer, and bringing the template into proximity with the substrate to provide contact between the embossed pattern of the template and the photo-curing resin. Then, the photo-curing resin fills in the embossed pattern of the template by capillary phenomenon and under this state, the photo-curing resin is irradiated with UV rays that cure the resin. A three-dimensional reverse pattern corresponding to the embossed pattern of the template is formed on the substrate. The template is then separated from the substrate.
In NIL, sometimes pattern slippage occurs between the template and the substrate to be treated during irradiation of the photo-curing resin with UV rays. Therefore it is desired in NIL to improve the superposition accuracy of the template and the substrate to be treated.
In general, the imprinting apparatus and imprinting method according to the embodiments are explained in detail by referring to the drawings attached. This disclosure is not limited to the embodiments.
According to the embodiments, there is provided an imprinting apparatus and an imprinting method capable of carrying out precisely the superposition of the template with the substrate to be treated.
According to one embodiment, an imprinting apparatus is provided. The imprinting apparatus is provided with a substrate holding part, a template holding part, an irradiation part, a pattern slippage quantity-detecting part and a control part. The substrate holding part holds the substrate to be treated and also moves the substrate to be treated along the in-plane direction (lateral direction). The template holding part holds a template having a three-dimensional embossed pattern formed thereon and moves the template along the in-plane direction; moreover it moves the template pattern against the resist after a pattern transfer material, such as a resist material, is dropped on the substrate to form a layer of transfer material thereon. The irradiation part irradiates light to cure the resist after the resist is filled into the recesses of the template pattern. The pattern slippage quantity-detecting part detects the quantity of pattern slippage between the substrate to be treated and the desired position of the template with respect to the substrate, and the control part controls at least one of the substrate holding part and the template holding part based on the pattern slippage quantity so as to mitigate the pattern slippage between the substrate to be treated and the template. The control part also controls the irradiation part so as to intermittently irradiate the curing light and also controls at least one of the substrate holding part and the template holding part based on the quantity of pattern slippage detected during the period when irradiation of the curing light is intermittently terminated.
The imprinting apparatus 101 comprises master stage 2, substrate chuck 4, sample stage 5, standard mark 6 (i.e., alignment mark), liquid dropping device 8, stage base 9, UV light source 10, and CCD (charge coupled device) camera 11. Furthermore, the imprinting apparatus 101 has a control device 20.
Wafer W is placed on sample stage 5, and it moves within the plane (horizontal plane) in parallel to the placed wafer W. Sample stage 5 shifts wafer W to the bottom side of the liquid dropping device 8 when resist as, a pattern transfer material, is dropped on wafer W and moves wafer W to face template T prior to affixing the template T for imprint treatment of wafer W.
Further, substrate chuck 4 is installed on sample stage 5. Substrate chuck 4 fixes wafer W at a prescribed position on sample stage 5. Further the standard mark 6 is formed on sample stage 5. Standard mark 6 is a mark for detecting the position of sample stage 5, and it is used for alignment when wafer W is loaded on sample stage 5.
Master stage 2 is installed at the bottom side (wafer W side) of the stage base 9. Master stage 2 fixes template T at a prescribed position from the back surface side (plane on the side where no template pattern is formed) of template T by vacuum adsorption, etc.
Stage base 9 supports template T by master stage 2, and moves the template pattern of template T toward the resist on wafer W. The stage base 9 conducts the pushing of template T against the resist, and pulls the template away from the resist to separate (mold release) the template T from the resist. The resist to be used for imprinting is, for instance, a resist material, such as photo-curable resin (photo-curing agent/chemical solution).
Further, CCD camera 11 is installed on the stage base 9. CCD camera 11 is a camera for detecting the positional relationship between an alignment mark Mt on template T (shown in
Liquid dropping device 8 is a device for dropping resist on wafer W via ink jet mode. The ink jet head (not shown) installed in liquid dropping device 8 has plural fine holes for jetting liquid droplets of resist.
UV light source 10 is a light source for irradiating with UV rays as a resist curing light and is installed on the upper part of the stage base 9. UV light source 10 irradiates UV rays to the upper side of template T, the underside of which is pushed against resist. Furthermore, the curing light may be any light without limitation thereof to UV wavelengths, so long as the light is capable of curing the resist or resin being patterned.
The control device 20 is connected to constituent elements of imprinting apparatus 101 and controls each constituent element. In
During conducting of imprinting on wafer W, wafer W, placed on sample stage 5, and is then shifted directly below liquid dropping device 8. Then, the resist is dropped on predetermined positions of wafer W (i.e., “shots”). The wafer may also be rotated, or spun, to spread the individual drops from the liquid dropping device 8 into a uniform thin film on the wafer.
Then, wafer W on sample stage 5, is positioned to be below template T, and template T is moved against the resist on wafer W. Control device 20 facilitates contact between template T and the resist until the resist fills in the pattern of template T.
After contacting template T with the resist for a predetermined time, control device 20 controls UV light source 10 to irradiate the resist so that the resist is cured. By this, a negative three-dimensional transfer pattern corresponding to the three-dimensional template pattern is incrementally cured in the resist on wafer W. Then, the imprinting process for the next shot is repeated. By this, imprint processing of all shots on wafer W is carried out to fully cure the resist in one shot curing intervals.
In this embodiment, curing light is intermittently irradiated during curing of the resist within the template pattern, and detection of the alignment signal is carried out when the irradiation of curing light is paused. In other words, detection of the alignment signal is carried out intermittently and irradiation of curing light is stopped when detection of the alignment signal is performed. By this, irradiation of curing light and detection of the alignment signal are carried out alternately (i.e., separately).
Next, the constitution of control device 20 is explained.
Image input part 21 sends images of the alignment of mark of Mt with mark Mw (both shown in
Pattern slippage quantity-detecting part 25 detects the positional relationship (pattern slippage quantity) of alignment mark Mt with respect to alignment mark Mw based on the alignment signal. The positional relationship of alignment mark Mt to Mw is a direct indication of the alignment, or misalignment, of template T and wafer W. Pattern slippage quantity-detecting part 25 according to this embodiment detects pattern slippage based on differences in position of the alignment mark Mt and Mw, based on the alignment signal, which is detected by alignment signal detection part 22 based on the order from timing control part 23. Pattern slippage quantity-detecting part 25 sends the pattern slippage revision quantity based on detected pattern slippage quantity to stage base control part 26 and sample stage control part 27.
Pattern slippage quantity-detecting part 25 sends, for instance, the pattern slippage revision quantity, which shifts the position of all shots in parallel, and the pattern slippage revision quantity, which shifts rotationally the position of the shots, etc. to sample stage control part 27. Further, pattern slippage quantity-detecting part 25 sends, for instance, a shot magnification-changing pattern slippage revision quantity that may be applied to all shots.
Timing control part 23 sends to alignment signal detection part 22 a detection instruction for facilitating detection of alignment signal and a detection-stoppage signal to cease detection of alignment signal. Further, timing control part 23 sends to light source control part 24 an irradiation facilitating initiation of curing light and an irradiation-stoppage signal to stop irradiation of curing light.
Timing control part 23 sends a signal detection stoppage order of alignment signal detection to alignment signal detection part 22 during sending of irradiation order to facilitate initiation of curing light to light source control part 24. On the other hand, timing control part 23 sends irradiation stoppage signal to stop irradiation of curing light to light source control part 24 during the sending of the detection signal to facilitate detection of alignment signal to alignment signal detection part 22. By this, one time period of irradiation of curing light and one time period of detection of the alignment signal (pattern slippage quantity) is carried out in imprinting apparatus 101 during curing of the resist filled template pattern.
Light source control part 24 controls UV light source 10. Light source control part 24 irradiates curing light to UV light source 10 when an irradiation initiation order of curing light is received from timing control part 23. On the other hand, light source control part 24 stops irradiation of curing light to the UV light 10 source when the irradiation stop order of curing light is received from timing control part 23.
Stage base control part 26 controls the position of stage base 9 based on the pattern slippage revision quantity sent from pattern slippage quantity-detecting part 25. Stage base control part 26 revises, for instance, the position of stage base 9 so as to make the modification of the shot and resolve pattern slippage errors.
Sample stage control part 27 controls the position of sample stage 5, based on the pattern slippage revision quantity sent from pattern slippage quantity-detecting part 25. Sample stage control part 27 revises, for instance, the position of sample stage 5 so as to make the desired position of a whole shot position (so as to resolve pattern slippage in parallel shifting or rotational shifting).
Timing control part 23, instead of alignment signal detection part 22, may send an order of processing or stoppage at a predetermined time to any part of CCD camera 11, image input part 21, and pattern slippage quantity-detecting part 25. Furthermore, timing control part 23 may send an order of processing or stoppage at a predetermined time to stage base control part 26 and sample stage control part 27.
Pattern slippage revision is carried out based on pattern slippage quantity detected during irradiation stoppage of curing light by sending a processing order to CCD camera 11, image input part 21, alignment signal detection part 22, pattern slippage quantity-detecting part 25, stage base control part 26 and sample stage control part 27 at the time of irradiation stoppage of curing light.
A detection order is sent to pattern slippage quantity-detecting part 25 during irradiation stoppage of curing light L1, for instance, when timing control part 23 sends an order of detection and order of stoppage to pattern slippage quantity-detecting part 25.
Now, the processing order of the imprinting process is explained.
Resist 12X is dropped on the upper surface of the wafer W as shown in
After filling resist 12X in template T only for a preset sufficient time, curing light irradiates so that resist 12X is cured. Then, template T is separated from the cured resist pattern 12Y, as shown in
Next, the imprint sequence by imprinting apparatus 101 is explained.
After pushing template T against resist 12X, filling of resist 12X is carried out (S4). At this time, alignment signal detection part 22 continues detection of the alignment signal, and pattern slippage quantity-detecting part 25 continues detection processing of the pattern slippage quantity and computation processing of the pattern slippage revising quantity. Further, stage base control part 26 continues position revision of stage base 9 while sample stage control part 27 continues position revision of sample stage 5.
When the filling of resist 12X is completed, intermittent exposure (irradiation of curing light L1) of resist 12X starts with individual discrete shots (S5). Further, between each shot, intermittent detection of alignment signal (S6), and pattern slippage revision between template T and wafer W is begun (S7). When the cumulative number of intermittent exposures of the resist 12X is sufficient to fully cure the resist, the, detection of alignment signal and intermittent pattern slippage revision between template T and wafer W are also terminated. Then, stage base 9 moves to separate template T from resist pattern 12Y (S8).
Now, process timing (on/off) of intermittent exposure processing, intermittent detection processing of alignment signal, and intermittent pattern slippage revision processing are explained.
Exposures shown in
As shown in
In
In
Like this, imprinting apparatus 101 repeats exposure and stop of exposure one to several times. Then, imprinting apparatus 101 conducts detection of the alignment signal during stopping of exposure. Furthermore, alignment signal detection and pattern slippage revision may be carried out at least once during a period in which the exposure is not occurring.
As shown in
On the other hand, as shown in
Imprint of alternate exposure and alignment signal detection is carried out in, for instance, each layer of the wafer process. In the production of semiconductor devices (semiconductor integrated circuit), imprint processing of forming film on wafer W and carrying out alternately exposure and alignment signal detection, and etching treatment of resist pattern 12Y formed by imprint processing, etc. are repeated in each layer.
According to the embodiment, it is possible to accurately detect the alignment signal since exposure is stopped during alignment signal detection. Thereupon, pattern slippage revision between template T and wafer W can be carried out accurately and, as a result, it is possible to carry out accurately superposition of template T and wafer W.
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.
Number | Date | Country | Kind |
---|---|---|---|
2012-030801 | Feb 2012 | JP | national |