The aforementioned and other objects and advantages of the present invention will become apparent to those skilled in the art upon reading and understanding the following detailed description with reference to the accompanying drawings.
In the drawings:
Preferred embodiments of the present invention will now be described in detail with reference to the attached drawings.
In the support frame unit, the lower base 10 and the upper base 14 are supported by the tie bars 12 fixed to the lower base 10 so that the lower base 10 and the upper base 14 are aligned and supported facing one another with high precision.
The setting table 20 supports a workpiece such as a semiconductor wafer or glass substrate that is set thereupon. The setting table 20 is raised and lowered using a raising/lowering mechanism including a motor 21 or the like disposed below the lower base 10 and can be aligned with the nano-imprinting mold 30 by a fine adjustment mechanism in the X-Y-θ directions.
A supplying apparatus 50 that supplies UV-curable resin (hereinafter simply “UV resin”) as a transfer material onto the workpiece is disposed on one side of the support frame unit. The supplying apparatus 50 includes a dispenser 52 that supplies a measured amount of the UV resin to the workpiece.
A conveying mechanism 60 that conveys a workpiece such as a semiconductor wafer or a glass substrate onto and off the setting table 20 is provided on the other side of the support frame unit. The conveying mechanism 60 includes a suction pad 62, which supports the workpiece by air suction, and a robot hand 64. The conveying mechanism 60 carries out an operation that conveys the workpiece 70 from a loader magazine 66 disposed beside the conveying mechanism 60 and stores the workpiece 70 after processing in an offloader magazine 68.
The setting table 20 that supports the workpiece 70 is composed of a support plate 22 that supports the workpiece 70, an intermediate plate 23 that supports the support plate 22, and a base plate 24. Through-holes 22a, 23a that pass through the support plate 22 and the intermediate plate 23 in the thickness direction are provided in the support plate 22 and the intermediate plate 23, and connecting channels 24a, 24b are provided in the base plate 24.
Since the support plate 22 is circular in planar form, as shown in
A main through-hole 22b is provided in the center of the support plate 22 and is connected via a through-hole 23b and a connecting channel 24b to an air mechanism 26 as a pumping/evacuating mechanism for gas. As shown in
Air suction holes 22c are provided in the support plate 22 so that the workpiece 70 is supported by evacuating air at an outer edge of the workpiece 70. The air suction holes 22c are connected to an air evacuating mechanism 27 via through-holes 22c and connecting channels 24c.
A discharge channel 22d for discharging the UV resin as the transfer material is provided so as to circle the support plate 22 at a position outside the region of the support plate 22 on which the workpiece 70 is set. The discharge channel 22d is connected to a discharge channel 23d provided in the intermediate plate 23 and the discharge channel 23d is provided so that one end thereof is open to the side surface of the intermediate plate 23. The discharge channel 22d is provided so as to discharge UV resin that has overflowed.
The mold frame holder 32 includes a locking portion 32a that supports and locks a flange portion 30a provided on the outer circumferential surface of the nano-imprinting mold 30 and a holder portion 32b that supports the locking portion 32a. The holder portion 32b is provided with a wide opening on a rear surface side thereof so as to allow UV light to be transmitted through the nano-imprinting mold 30. An opening for allowing UV light to be transmitted is also provided in the upper base 14.
A process that forms the required convexes and concaves is carried out on a mold surface of the nano-imprinting mold 30 to form the required convex/concave pattern. The construction of the nano-imprinting mold 30 is described in detail later in this specification.
Next, the processes of an imprinting operation carried out on the workpiece 70 using the nano-imprinting apparatus shown in
First, according to control by the control unit 90, the motor 21 is controlled and driven to lower the setting table 20 to a lower position where the workpiece 70 is supplied to the setting table 20. The operation that supplies the workpiece 70 to the setting table 20 is carried out by picking up a workpiece 70 that protrudes from the loader magazine 66 on the suction pad 62 using suction and supplying the workpiece 70 to the setting table 20 using the robot hand 64.
After the workpiece 70 has been placed on the support plate 22, the air mechanism 25 and the air evacuating mechanism 27 are used to support the workpiece 70 on the setting table 20 by suction, and then the workpiece 70 is aligned with the nano-imprinting mold 30. This aligning operation can be carried out for example by optically detecting alignment marks provided on the workpiece 70 and then aligning the setting table 20 using the fine adjustment mechanism in the X-Y-θ directions in accordance with the detection result for the alignment marks.
Next, UV resin 80 is supplied on to the workpiece 70 by the UV resin supplying apparatus 50. The supplied amount of the UV resin 80 exceeds the amount required to fill the concave parts of the nano-imprinting mold 30 when the UV resin 80 is clamped by the workpiece 70 and the nano-imprinting mold 30 by around 20%.
The supplied amount and applied shape of the UV resin 80 supplied to the workpiece 70 can be appropriately adjusted via the planar form of the workpiece 70 and the like, but in view of the operability and the molding variation during mass production, by carrying out molding by supplying an amount of resin produced by adding an overflow amount to the minimum amount of resin required for molding, it is possible to stabilize the molding quality of the outer circumferential part of the workpiece 70. Note that it is necessary to determine the overflow amount of resin in accordance with the workpiece 70 with consideration to factors such as the flow characteristics of resin on the surface of the workpiece 70.
Although the UV resin 80 is supplied to the workpiece 70 so that the planar form of the supplied UV resin 80 is fundamentally circular, there are cases where the shape in which the UV resin 80 spreads out is distorted and is not circular due to factors such as the planar form of the workpiece 70 and patterns formed on the workpiece 70. Accordingly, it is possible to feed back molding results to adjust the shape in which the UV resin 80 is applied and/or to supply the UV resin 80 so that the applied UV resin 80 is higher (i.e., thicker) in the center. By increasing the supplied amount of resin with consideration to the amount that will overflow, it will be possible to fill the concave parts with the UV resin 80 without leaving unfilled areas.
Depending on the pattern formed on the surface of the workpiece 70, it may also be effective to apply the UV resin by dispersing the UV resin in a cross shape or in many dots.
After the UV resin 80 has been supplied, the motor 21 is driven to raise the setting table 20.
When the distance of separation between the mold surface of the nano-imprinting mold 30 and the surface of the workpiece 70 is 0.005 μm to 1 μm, the setting table 20 is stopped. This position is the height of the setting table 20 at which the imprinting operation is finally carried out.
The imprinting operation of the present embodiment is characterized by the upper position (i.e., the “filling operation position”) to which the setting table 20 is raised being set so that a gap is provided between the surface of the workpiece 70 and the nano-imprinting mold 30 and therefore the surface of the workpiece 70 does not completely contact the mold surface of the nano-imprinting mold 30. Since the thickness of the workpiece 70 differs between products, the distance of separation provided between the support plate 22 of the setting table 20 and the nano-imprinting mold 30 will differ depending on the workpiece 70.
Note that since there are fluctuations in the thickness of the workpiece 70, the thickness of the workpiece 70 is detected in advance, the detection result is transferred to the press, and the stopping position is controlled for each workpiece 70 so that the separation provided between the nano-imprinting mold 30 and the workpiece 70 is set within a range of predetermined values.
After the setting table 20 has been stopped at the upper position (the filling operation position), the air mechanisms 25, 26 are driven to pump air toward the lower surface of the workpiece 70 supported on the support plate 22.
Note that when air is pumped from the air mechanisms 25, 26, the air is first pumped out of the main through-hole 22b positioned in the center of the support plate 22 and is gradually pumped out from the through-holes 22a positioned further out on the support plate 22. For the air mechanism 25, the timing for pumping air is controlled in accordance with the layout of the through-holes 22a. Since the air mechanism 26 pumps air to the main through-hole 22b positioned in the center of the support plate 22, the air mechanism 26 is controlled to pump air before the other through-holes 22a.
As shown in
By setting the distance of separation between the workpiece 70 and the mold surface of the nano-imprinting mold 30 at around 0.005 μm to 1 μm and blowing air to raise the workpiece 70 while the outer edge of the workpiece 70 is being supported, it is possible to prevent displacement of the workpiece 70 and to reliably press the workpiece 70 onto the nano-imprinting mold 30.
UV light is emitted from above the nano-imprinting mold 30 in a state where the workpiece 70 is being pressed onto the nano-imprinting mold 30 by air pressure, resulting in the UV resin 80 being hardened by the UV light transmitted through the nano-imprinting mold 30. By doing so, the UV resin 80 becomes hardened and attached to the surface of the workpiece 70.
After the UV resin 80 has been hardened by irradiation with UV light for a fixed period, the air mechanisms 25, 26 switch to carrying out an evacuating operation that pulls the workpiece 70 by vacuum suction. In this way, by lowering the workpiece 70 to the support plate 22 by suction, the hardened resin 80a and the workpiece 70 become detached from the nano-imprinting mold 30. The setting table 20 is then lowered together with the workpiece 70 to the lowered position (the conveying position).
Next, the robot hand 64 of the conveying mechanism 60 is moved into the imprinting operation unit, the workpiece 70 that has been imprinted is held by the suction pad 62 and the workpiece 70 is stored inside the offloader magazine 68. When the workpiece 70 that has been imprinted is picked up by the suction pad 62 using suction, air is expelled from the air mechanisms 25, 26 to separate the workpiece 70 from the support plate 22 and allow the workpiece 70 to be transferred.
Note that as another method of transporting the imprinted workpiece 70, it is possible to use a method that lowers only the setting table 20 to the lower position after the UV resin 80 has been hardened with the workpiece 70 still adhering to the workpiece 70. The imprinted workpiece 70 is then detached from the nano-imprinting mold 30 and stored in the offloader magazine 68 using the conveying mechanism 60.
In this case, it is possible to lower the setting table 20, to insert the robot hand 64 with the suction surface of the suction pad 62 facing upward, to attach the lower surface of the workpiece 70 to the suction pad 62 by suction, and to then detach the imprinted workpiece 70 by operating the robot. Here, it is possible to detach the entire workpiece 70 from the nano-imprinting mold 30 by tilting the workpiece 70 so that the workpiece 70 is gradually pulled off from one outer edge thereof.
As shown in
The workpiece 70 is pressed onto the nano-imprinting mold 30 using air pressure in this way since it is possible to press the workpiece 70 so that the workpiece 70 assumes the shape of the mold surface of the nano-imprinting mold 30.
When using a mold (such as the nano-imprinting mold 30) in which an extremely minute pattern is formed, if the workpiece 70 were completely pressed onto the mold, fluctuations in the thickness of the workpiece 70 and undulations in the surface of the workpiece 70 would appear as fluctuations in the form of the molded product (i.e., in the form of the UV resin). As a method of eliminating such fluctuations in the workpiece, it is preferable to prevent fluctuations in the workpiece 70 from affecting the imprinted pattern. With the nano-imprinting apparatus according to the present embodiment, the workpiece 70 is pressed so as to assume the shape of the mold surface of the nano-imprinting mold 30, or in other words, the UV resin 80 is imprinted by pressing the workpiece 70 with the mold surface of the nano-imprinting mold 30 as the standard surface, and therefore imprinting is carried out according to a condition where fluctuations in the thickness and non-uniformity of the workpiece 70 are not reflected. That is, the convex/concave pattern of the nano-imprinting mold 30 is accurately transferred to the imprinted UV resin 80.
The present embodiment is set so that when the workpiece 70 is pressed onto the nano-imprinting mold 30, the workpiece 70 starts being pressed onto the nano-imprinting mold 30 from a central part of the workpiece 70 and the pressed part gradually expands to the periphery of the workpiece 70. In this way, by pressing the workpiece 70 toward the nano-imprinting mold 30 from the central part of the workpiece 70, it is possible to fill the UV resin 80 without air becoming trapped in the parts of the nano-imprinting mold 30 that have been filled with resin.
During nano-imprinting using the nano-imprinting mold 30, it is necessary to prevent bending of and/or damage to the nano-imprinting mold 30 due to the action of the resin pressure on the nano-imprinting mold 30 when the resin is molded. When the workpiece 70 is pressed onto the nano-imprinting mold 30 as in the present embodiment, by pressing the workpiece 70 onto the nano-imprinting mold 30 from the central part of the workpiece 70 so as to cause the UV resin 80 to flow from the central part of the workpiece 70 toward the outside, it is possible to prevent the nano-imprinting mold 30 from bending due to resin pressure. If the nano-imprinting mold 30 bends and deforms due to resin pressure, resin will accumulate in spaces produced by the bending and the thickness of the resin can easily vary by as much as 500 nm (0.5 μm) for example, which is one hundred times the intended thickness of 5 nm.
Although air is pumped from both the main through-hole 22b and the through-holes 22a when pumping air to raise the air pressure at the lower surface of the workpiece 70 in the present embodiment, the method of pumping air can be set as appropriate in accordance with the material, size, and the like of the workpiece 70. For example, if the required air pressure can be obtained by pumping air via only the main through-hole 22b, it is possible to carry out imprinting by carrying out control so that air is pumped from only the main through-hole 22b. The positions at which the through-holes 22a for pumping air are provided in the support plate 22 and the like can also be selected as appropriate. When air is expelled from the through-holes 22a, it is possible to appropriately select the through-holes 22a from which air is expelled and to appropriately control the air pressure for each through-hole 22a that is expelling air.
In the same way as the embodiment described above, with the setting table 20 according to the present embodiment, the workpiece 70 is set on the setting table 20 and air is expelled from the through-holes 22a to press the workpiece 70 onto the nano-imprinting mold 30 by air pressure so that the convex/concave shape of the nano-imprinting mold 30 is imprinted into the UV resin 80.
With the support plate 22 according to the present embodiment, by using a construction where the through-holes 22a are provided in the inner bottom surfaces of the pockets 22e, it is possible to cause the air pressure of the air expelled from the respective through-holes 22a to act across a wider area of the workpiece 70, so that the air pressure acts uniformly on the workpiece 70.
In the present embodiment, in the same way as the embodiment described above, the timing at which air is introduced from the through-holes 22a is controlled so as to implement control so that the contacting part of the nano-imprinting mold 30 and the workpiece 70 gradually increases from the center of the workpiece 70 toward the outer edge of the workpiece 70. The contact between the workpiece 70 and the nano-imprinting mold 30 can be visually confirmed from differences in the angle of reflection of light seen through the nano-imprinting mold 30, and therefore control can be carried out to adjust the timing of introducing air into the individual through-holes 22a and the air pressure of the individual through-holes 22a while monitoring the contact between the workpiece 70 and the nano-imprinting mold 30.
When controlling the contact (i.e., the gap) between the workpiece 70 and the nano-imprinting mold 30, it is necessary to guide the UV resin 80 to the parts that are yet to be filled with the UV resin 80 by using capillary action and to reliably generate an action that guides the air from such unfilled parts toward a low pressure area so as to press the air out from the workpiece 70. This means that a method that controls the air pressure introduced from through-holes 22a to the rear surface of the workpiece 70 while actually detecting the pressing state (i.e., the contact) between the workpiece 70 and the nano-imprinting mold 30 can carry out a reliable imprinting operation with no fluctuations.
Note that although air is used to press the workpiece 70 onto the nano-imprinting mold 30 in the embodiment described above, it is also possible to use nitrogen gas or another gas in place of air.
Also, although a construction is used in the embodiment described above where the support plate 22 and the intermediate plate 23 are used and the through-holes 22a, 23a are provided in the support plate 22 and the intermediate plate 23, flow channels formed in the support plate 22 and the like only need to cause air pressure to act on the workpiece 70 or to evacuate air from the workpiece 70 and therefore it may not be necessary to form through-holes. Through-holes for connecting to mechanisms for pumping and evacuating gas may be provided in the surface of the setting table 20 on which the workpiece 70 is set.
Although imprinting is carried out in the embodiment described above using a construction where it is possible to raise and lower the workpiece 70 with respect to the lower base 10, the nano-imprinting mold 30 is fixed to the upper base 14, and the workpiece 70 is movable with respect to the nano-imprinting mold 30, it is also possible to carry out imprinting with a construction where the workpiece 70 is fixed and the nano-imprinting mold 30 is capable of being raised and lowered. In this case also, it is possible to use an operation where UV-curable resin is filled between the workpiece 70 and the nano-imprinting mold 30, with the workpiece 70 being pressed onto the nano-imprinting mold 30 using the pumping/evacuating mechanism for gas described earlier.
A mold in whose surface concave channels are formed in a predetermined pattern is used as the nano-imprinting mold. As shown in
With the nano-imprinting mold 30 used in the present embodiment, a collection channel 31 for collecting the UV resin 80 that has overflowed when the UV resin 80 is clamped is provided so as to surround an outer edge of the nano-imprinting mold 30.
Although the UV resin 80 flows comparatively quickly across the surface of the workpiece 70 when the UV resin 80 is clamped by the nano-imprinting mold 30 and the workpiece 70, the UV resin 80 trapped in the collection channel 31 will gather inside the collection channel 31, thereby causing a drop in the speed at which the UV resin 80 is discharged to the outside. This means that by forming a trap wall 31a around the outer circumferential surface of the collection channel 31, it is possible to prevent the UV resin 80 from leaking outside the collection channel 31.
In
The depth and width of the collection channel 70a are set so as to produce a sufficient capacity for holding the UV resin that has flowed into the collection channel 70a and the width of the collection channel 70a is set so as to prevent the UV resin 80 from being discharged outside the collection channel 70a due to the flow speed of the UV resin 80 flowing into the collection channel 70a. In the present embodiment the width of the collection channel 70a is set at 0.1 mm and the depth is set at 0.05 mm.
A stepped concave part 30c is provided in the nano-imprinting mold 30 so as to face the collection channel 70a so that a sufficient distance of separation is provided at the facing parts of the collection channel 70a and the nano-imprinting mold 30. If sufficient separation is provided between the collection channel 70a and the nano-imprinting mold 30 in this way, when the UV resin 80 flows into the collection channel 70a, it will be possible for the UV resin 80 to reliably enter the collection channel 70a of the workpiece 70. By curing the UV resin 80 that has been introduced into the collection channel 70a using light, it is possible to prevent contamination of the resin, such as when the workpiece 70 is conveyed. It is also possible to wash the UV resin 80 introduced into the collection channel 70a in a separate process.
Since the UV curable resin used in the present invention forms a predetermined convex/concave pattern on the surface of the workpiece 70 and such predetermined convex/concave pattern is etched to form a mask, there are cases where a filler such as silicon is mixed into the resin to improve the etching resistance of the resin. In this way, when using UV resin in which filler has been mixed, the distance of separation (i.e., the gap) between the workpiece 70 and the nano-imprinting mold 30 needs to be set and the size of the filler needs to be selected so as to ensure that the filler can flow in the separation (i.e., gap) between the surface of the nano-imprinting mold 30 and the surface of the workpiece 70.
In this way, when the filler diameter becomes around ⅓ of the thickness of the fluidized bed for the resin, the filler coagulates and as a result, a phenomenon occurs where the filler density rises and parts where the resin is depleted are formed across the entire thickness of the resin from the surface of the molded object. Such parts where the density of the filler is high and the resin component is depleted appear in petal shapes, and such petal-shaped parts are concentrically disposed so as to radiate from a center part, just like a sunflower.
Such molded products are non-uniform and therefore defective. It was understood through experimentation that this problem can be solved by setting the diameter of the filler at around ⅓ of the thickness of the molded product or below. Here, it is supposed that when the filler diameter is reduced, the positions of the petals are shifted toward the outside of the product, and when the diameter is reduced further, the petals do not occur within the product.
Accordingly, during semiconductor nano-imprinting, when the thickness of the thin parts of a molded product is 7 nm and the thickness of the thick parts is 20 nm, superior compression molding quality is achieved when the filler diameter is set at 4 nm and even higher molding quality can be expected when the filler diameter is set at 2 nm or below.
Number | Date | Country | Kind |
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2006-134795 | May 2006 | JP | national |