JP2004103817A - Imprint method and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that gas is sealed in the recessed part of a mold and a predetermined pattern is not formed when a resist enters the recessed part of the mold upon imprint wherein the mold with a predetermined recessed and projected pattern thereon is pressed against the resist to transfer the same. <P>SOLUTION: The mold 7 with the recessed and projected pattern 8 thereon is pressed against a resist layer 5 on the surface of a substrate 6 movable horizontally in a working chamber 1 whereby the imprint of the recessed and projected pattern on the mold 7 is effected onto the resist layer 5. Gas in the working chamber 1 is exhausted by an exhausting device 11 and a gas having a predetermined nature is supplied from a compressed gas supply device 15. When a resist layer enters the recessed part of the mold on imprint, the gas in the recessed part is compressed and condensed upon the imprint. Therefore, the liquescent gas is selected. The volume of the gas becomes negligible by the condensation whereby the generation of a fault due to the sealed gas in the recessed part of the mold is prevented. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an imprint in which a mold having a predetermined pattern formed is pressed against a resist layer applied to a substrate surface or a supplied resist, and a transfer defect due to an atmosphere forming gas captured between the mold and the resist. The present invention relates to an imprint method and an imprint apparatus for performing the method, which are performed in a gas atmosphere that is condensable at the temperature and pressure during imprint in order to reduce the amount.
[0002]
[Prior art]
In recent years, downsizing of ultra LSI devices typified by high density memories and system LSIs has progressed, and a technology capable of further miniaturization is required. Therefore, lithography (transfer) technology is important in a semiconductor manufacturing process. Sex is increasing. In addition, there is a need for a processing technique for producing a large amount of nanostructures at low cost. The imprint technique is a technique of pressing a mold having a predetermined circuit pattern formed thereon against a sample substrate having a surface coated with a resist, and transferring the pattern. Various methods have been proposed, for example, as shown in FIG. It is done so that
[0003]
In FIG. 4, a reverse pattern corresponding to a mirror image of a pattern to be transferred is first formed on the surface of the mold material 20 by electron beam lithography or the like as shown in FIG. Is created. On the other hand, as shown in FIG. 2B, a resist material such as PMMA is applied on a base material 23 such as a silicon substrate on which a pattern is to be formed, and cured to form a resist layer 24.
[0004]
Next, the entire substrate 23 provided with the resist layer 24 is heated to about 200 ° C. to slightly soften the resist layer 24. In this state, as shown in FIG. 4C, the uneven shape 21 of the mold 22 is arranged at a predetermined position on the resist layer 24, and the uneven shape 21 is pressed against the resist layer 24. At this time, since the resist layer 24 is softened, a part of the resist layer 24 enters the concave portion of the uneven shape 21 as shown in FIG. 4D, and the resist layer 24 has substantially the same shape as the uneven shape 21. In this state, the entire temperature is lowered to about 105 ° C. to cure the resist layer 24. Thereafter, the mold 22 is removed as shown in FIG. In this way, a concavo-convex pattern 25 having a predetermined shape is formed on the resist layer 24.
[0005]
Thereafter, when performing imprinting on another portion of the substrate 23, as shown in FIG. 4F, the mold 22 is moved to the upper portion of the portion relative to the substrate 23, and the same as described above. Then, the mold 22 is pressed against the resist layer 24 at that portion. Hereinafter, the same operation is continuously performed on all the predetermined positions with respect to the base material 23 to perform a predetermined imprint.
[0006]
In the imprint technology, in addition to the above, for example, a mold is made of a transparent material such as a quartz substrate, and a liquid photocurable resin is applied on the substrate to be transferred, and the mold is formed thereon. Pressing the irregularities on the surface, flowing liquid photocurable resin into the irregularities, irradiating light through the mold, curing the photocurable resin, and then removing the mold to form an irregular pattern of a predetermined shape Has also been proposed.
[0007]
[Patent Document 1]
JP 2001-198979 A [Patent Document 2]
JP 2000-289258 A [Patent Document 3]
JP-A-9-109190
[Problems to be solved by the invention]
In the imprint technology as described above, when pressing the mold against the resist, if this is done in the air atmosphere, the air will be trapped between the mold recess and the resist, and the air will stay after pressing, so the mold shape can be accurately transferred. Disappears. For example, as shown in FIG. 5A, the air taken in when the mold 22 is pressed against the base material 23 is compressed in this space and its volume is reduced, but remains at this location. At this time, as shown in FIG. 5B, not only when the taken-in air after compression stays uniformly in the mold concave portion, but also due to the action of the resin that reduces the flow of the resin and the energy of the resin surface, FIG. 5), the foamed portion 17 remains in the mold concave portion, and as shown in FIG. 5 (d), a missing portion 19 is formed in the pattern portion 18 on the resist layer after the transfer operation is completed, thereby impairing the transfer accuracy. .
[0009]
As a countermeasure, there are a method in which the step of pressing the mold against the resist by the imprint technique is performed in a vacuum, and a method in which the volume of the taken-in atmosphere is reduced by increasing the pressure for pressing the mold extremely. However, the former requires a rugged vacuum layer that can withstand 1 atm for evacuating the device, and the latter cannot use high-precision transfer because the mold itself is deformed due to the use of large pressure. This can also cause damage to the mold and substrate material.
[0010]
Therefore, the present invention prevents a decrease in transfer accuracy due to the incorporation of gas forming the atmosphere for imprint operation even at a relatively low pressure (1 MPa or less) without using vacuum in imprint technology. It is a primary object of the present invention to provide an imprint method and apparatus utilizing gas condensability.
[0011]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 of the present application provides an imprint for transferring an uneven shape formed on a mold to a resist layer applied on a base material surface or a supplied resist. The method is performed in an atmosphere of a gas condensing at a temperature at which the resist layer penetrates into the concave portion formed at the pressure and a pressure in the concave portion.
[0012]
According to a second aspect of the present invention, there is provided the imprint method according to the first aspect, wherein a vapor pressure of the gas at a normal temperature is 0.05 MPa or more and 1.00 MPa or less.
[0013]
According to a third aspect of the present invention, there is provided the imprint method according to the first aspect, wherein the gas has a boiling point of 15 ° C. or more and 30 ° C. or less at atmospheric pressure.
[0014]
According to a fourth aspect of the present invention, there is provided an imprint apparatus comprising: a mold having an uneven shape on a surface; a substrate having a resist layer formed on the surface; and a mold driving device for pressing the mold against the resist layer. A gas supply device for supplying a gas condensed at a temperature and a pressure at the time when the resist layer enters a concave portion formed in the mold at the time of imprint to a mold surface which is at least separated from the resist layer to the imprint work portion. An imprint apparatus characterized by comprising:
[0015]
According to a fifth aspect of the present invention, in the imprint apparatus, the vapor pressure of the gas at a normal temperature is 0.05 MPa or more and 1.00 MPa or less in the imprint apparatus. Things.
[0016]
According to a sixth aspect of the present invention, there is provided the imprint apparatus according to the fourth aspect, wherein a boiling point of the gas at atmospheric pressure is 15 ° C. or more and 30 ° C. or less.
[0017]
The invention according to claim 7 is the imprint apparatus according to claim 4, wherein the gas supply device supplies the gas so that a closed space has a predetermined pressure.
[0018]
In the invention according to claim 8, the gas supply device supplies the gas to the imprint portion in an open space, and the gas compensates for dissipation from the imprint portion by diffusion. An imprint apparatus according to claim 4, wherein the imprint apparatus is supplied.
[0019]
The invention according to claim 9 is the imprint apparatus according to claim 4, wherein the gas supply device supplies the gas so that a gas flow of the gas is generated in the imprint work portion. It is.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows an overall schematic view of an embodiment of the present invention. In a work chamber 1, a substrate moving stage 3 is movably arranged on a surface plate 2 in a horizontal plane. Holds a silicon substrate 6 provided with a resist layer 5 on the surface. The silicon substrate 6 is large enough to imprint a plurality of concavo-convex patterns 8 of a mold 7 for transferring to the resist layer 5.
[0021]
On the other hand, a mold driving stage 9 for moving the mold 7 up and down and pressing the uneven pattern 8 on the lower surface of the mold against the resist layer 5 located below the mold 7 is fixed in the working chamber 1. When the silicon substrate 6 is moved by the moving stage 3 and stopped at a predetermined position, the mold pressing mechanism 10 of the mold driving stage 9 is operated to press the concave and convex pattern 8 on the lower surface of the mold 7 against the resist layer 5. It has become.
[0022]
The working chamber 1 is provided with an exhaust device 11, the discharge side opening / closing valve 12 is opened, the supply side opening / closing valve 13 described later is closed, and the pump is driven to evacuate the atmosphere in the working chamber 1. A condensable gas of a predetermined component can be supplied to the chamber 1 from an external condensable gas supply device 15 via a supply-side opening / closing valve 13. At that time, the pressure in the working chamber 1 is detected by the pressure sensor 15, and the condensable gas is supplied so that the inside of the working chamber 1 has a predetermined pressure. At this time, the temperature in the working room is detected by a temperature sensor 16 by a separately provided indoor gas temperature control device, and the temperature in the working room can be adjusted to an appropriate temperature, for example, 23 ° C. as a normal temperature. In addition, as described later, the “condensable gas” is, as described later, condensed by the pressure when the resist layer enters the concave portion of the mold during the imprint operation and compresses the gas trapped inside the concave portion. Gas that can be used.
[0023]
Various gases can be selected as the condensable gas. For example, trichlorofluoromethane having a vapor pressure of 0.1056 MPa at room temperature (23 ° C.) can be used. Is also supplied at a predetermined low pressure, for example, about 0.1 MPa. The boiling point of the substance constituting such a condensable gas atmosphere is preferably about 15 ° C. to 30 ° C. near normal temperature when the pressure in the working chamber is about 1 atm. However, depending on the type of the condensable gas, it is appropriately changed in relation to the pressure setting in the working chamber.
[0024]
When an imprinting operation is performed in such a condensed gas atmosphere, an appropriate imprinting operation according to the present invention can be performed by the operation shown in FIG. 2, for example. In FIG. 2, similarly to the apparatus used in the apparatus shown in FIG. 1, a mold 7 having a specific uneven pattern 8 formed on the lower surface is pressed against the surface of a silicon substrate 6 having a resist layer 5 on the surface. This shows an initial state in which a printing operation is performed, and shows a state in which the concavo-convex pattern 8 of the mold 7 is in contact with the resist layer 5. At this time, the concave portion 25 in the concave / convex pattern 8 on the lower surface of the mold 7 is shielded from the outside world, so that the condensable gas 30 in the concave portion 25 is in a sealed state.
[0025]
Thereafter, when the mold 7 is moved down by the mold driving and moving stage 9 in FIG. 1, the convex portions 26 of the concave / convex pattern 8 are pushed into the softened resist layer 5 as described above. Invade. As a result, the condensable gas 30 in the sealed state as described above in the concave portion 25 is compressed, and the pressure increases.
[0026]
When the convex portion 26 of the concavo-convex pattern 8 is pushed into the resist layer 5 when the mold 7 descends, the resist layer 5 is surrounded by the convex portion 26 of the outer periphery 27 of the mold 7 in particular, so that the resist layer 5 is surrounded. Although the inner resist layer 5 moves partly outside the outer periphery 27 of the mold 7 as the mold 7 descends, many resist layers 5 cannot move and are in a compressed state. Therefore, the resist layer 5 enters the recess 25 of the mold 7 to a position higher than the height of the first surface of the resist layer 5. This state is shown in FIG.
[0027]
In this manner, the mold 7 is finally pressed to a predetermined pressure, for example, about 0.5 MPa, and its lower surface is raised to the final position in the resist layer 5 as shown in FIG. When it enters, the resist layer 5 in the concave portion 25 further rises in that space, and compresses the condensable gas 30 inside. In the course of this compression, the temperature of the condensable gas 30 naturally rises. However, in the field of imprint lithography, the volume is extremely small, the surface area is large, and the heat capacity of the mold 7 is large. As described above, the heat generated during the compression process is removed to the surroundings, and is maintained at substantially the same temperature as the set temperature in the working part.
[0028]
Since the resist layer 5 that has penetrated deeply into the concave portion 25 of the mold 7 compresses the condensable gas 30 therein, the pressure of the condensable gas increases in proportion to the volume decrease. When a gas that becomes liquid at the time of the above-described compression is selected at the temperature of the working part as described above, the condensable gas used here is compressed in the recess 25 by the compression of the condensable gas 30 as described above. A part of the condensable gas 30 is liquefied.
[0029]
Due to the liquefaction of the condensable gas 30 in the concave portion 25, the volume of the condensable gas 30 differs precisely depending on the property (molecular weight) of the gas, but becomes smaller by about two orders of magnitude. Will be kept. As a result, when the pressure applied to the resist layer 5 is higher than the vapor pressure of the gas, liquefaction of the gas occurs continuously, and finally all the gas liquefies, and the resist that has entered the recess 25 as described above. The layer 5 is in a state of filling almost all the space of the concave portion 25 as shown in FIG. 2D, for example.
[0030]
Thereafter, the mold 7 is raised, and the concavo-convex pattern 8 is separated from the resist layer 5 in the same manner as that shown in FIG. 4E, and the silicon substrate 6 is moved in the horizontal direction by the base moving stage 3. A resist layer 5 to be imprinted next is positioned on the lower surface, and the same operation is performed thereafter.
[0031]
As described above, when the mold 7 is lifted and the concavo-convex pattern 8 is separated from the resist layer 5, the condensed liquid in the concave portion 25 returns to the original pressure. Mix with.
[0032]
By performing the above operation, it is possible to solve the problem that the uneven pattern cannot be accurately transferred due to the remaining compressed gas in the concave portion as in the conventional imprint shown in FIG.
[0033]
As described above, in the present invention, the conventional problem can be solved by performing the imprinting operation in an atmosphere in which a condensable gas of a predetermined property is present in the surroundings. The means for performing this operation can be implemented in various modes. For example, in FIG. 1, the inside of the working chamber 1 is filled with a condensable gas of a predetermined property while the inside thereof is filled, and the work can be performed therein. At that time, a means for controlling the pressure and temperature so as to maintain the inside of the working chamber at a predetermined pressure and maintain the predetermined temperature may be provided.
[0034]
Further, in a state where the normal atmosphere is present in a relatively large working space, the above-described imprinting work can be performed, and the portion for performing the imprinting work is described above. An apparatus for supplying a condensable gas may be provided so that the imprint operation can be performed in the condensable gas. At that time, the condensable gas supplied as described above escapes to the surroundings, and thus the condensable gas that has escaped is replenished from the gas supply device.
[0035]
In addition, a condensable gas supply device that can always form a condensable gas flow for a portion where an imprint operation is performed is provided when the working chamber is a closed space as described above and when the large working space is almost in an atmospheric state. Alternatively, the imprint operation may be performed in such a condensable gas flow.
[0036]
As described above, as the condensable gas forming the atmosphere of the imprint work portion, a gas that condenses at least the pressure at the time when the inside of the concave portion 25 of the mold 7 is finally compressed during the imprint work is used. . In this case, various condensable gases can be used. When selecting the condensable gas, for example, a condensing curve of various gases as shown in FIG. 3 is selected as a reference.
[0037]
In the condensation curves of various gases shown in FIG. 3, for example, as is clear from the condensation curve of water vapor shown in the lower right of FIG. 3, water condenses at 100 ° C. and water at an atmospheric pressure of 0.1013 MPa. However, at low temperatures, water condenses at lower pressures, and conversely, at high temperatures, water at higher pressures. Similarly, in the gas shown as C1 in the figure (a gas such as trichlorofluoromethane conventionally used as the refrigerant R11), for example, when the pressure is atmospheric pressure, the gas condenses at approximately 20 ° C. It can be seen that when the pressure is increased to 2 MPa, condensation occurs at approximately 40 ° C. Similarly, the gas (gas such as refrigerant R12) shown as C2 in the figure liquefies at about 0.5 MPa at 20 ° C. and 1 MPa at 40 ° C.
[0038]
When the temperature of the gas is constant, the pressure increases in proportion to the volume (P × V / T = constant). For example, the concave and convex pattern 8 of the mold 7 is pressed against the resist layer 5 as shown in FIG. When the volume of the condensable gas 30 in the recess 25 is reduced by half, the pressure of the condensable gas is doubled, and when the volume is reduced by one third, the pressure of the condensable gas is reduced. Is tripled. Therefore, a condensable gas which is a gas in the pressure state of the working chamber is compressed as described above to reduce its volume and to be condensed in a state where the pressure increases.
[0039]
For example, when the gas C1 in FIG. 3 is used as the condensable gas, the working chamber is set to the atmospheric pressure, the working portion is set to 40 ° C., and the above-described imprinting operation is performed. Shortly before the inside of the recess 25 is reduced by half, the condensable gas 30 inside the recess 25 condenses. Similarly, when the working portion is at 30 ° C. and the atmospheric pressure, when the pressure in the concave portion 25 becomes about 0.15 MPa, that is, when the volume of the concave portion 25 decreases by about 1/3, that is, 2/3 of the initial volume When it reaches the level, it condenses and liquefies.
[0040]
Further, for example, when the gas C2 in FIG. 3 is used as the condensable gas, if the imprint operation is performed on the working portion at 20 ° C. and 0.2 MPa, the resist layer 5 enters the concave portion 25 and the volume becomes 1 /2.5, and condenses when the internal pressure becomes about 0.5 MPa. Therefore, the present invention can be carried out using such a gas C2. However, if the temperature of the working part is to be carried out at about the atmospheric temperature, the working chamber must be constantly raised to about 0.2 MPa or more. And the equipment in the working room must be expensive. Conversely, when the steam in FIG. 3 is used, if the operation is to be performed with the temperature in the working room at about room temperature, the operation must be performed at an extremely low pressure, and the temperature in the other working room must be 100 ° C. or more. The facilities related to the work room must be large-scale.
[0041]
As described above, although various condensable gases can be used in the present invention, it is preferable that the working room be at room temperature and at about atmospheric pressure as much as possible in consideration of equipment costs and the like. When a gas widely used as a gas is used, a condensable gas capable of performing the above-mentioned operation at a normal temperature (23 ° C.) at a pressure of about 0.05 to 1 MPa or a large condensable gas near a normal temperature (15 ° C. to 30 ° C.) It is preferable to use a condensable gas having a vapor pressure equal to the atmospheric pressure, that is, a condensable gas having a boiling point of 15 ° C to 30 ° C.
[0042]
【The invention's effect】
In the present invention, by performing the imprint process in a gas having a condensable property, air bubbles trapped even at an imprint pressure of about several atmospheres can be almost eliminated, and accurate imprint can be easily performed at atmospheric pressure. It can be performed by an inexpensive device.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an overall system of an embodiment of an imprint apparatus according to the present invention.
FIG. 2 is a schematic diagram showing an operation state when performing imprinting in a condensable gas atmosphere according to the present invention.
FIG. 3 is a condensation curve showing the manner in which various gases condense due to changes in ambient temperature and pressure.
FIG. 4 is a schematic view showing a process of imprint.
FIG. 5 is a schematic diagram showing a problem during a conventional imprint operation.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Working room 2 Surface plate 3 Substrate moving stage 5 Resist layer 6 Silicon substrate 7 Mold 8 Concavo-convex pattern 9 Mold drive stage 10 Mold pressing mechanism 11 Exhaust device 12 Discharge side open / close valve 13 Supply side open / close valve 15 Condensable gas supply device

Claims (9)

The imprint that transfers the uneven shape formed on the mold to the resist layer applied on the substrate surface or the supplied resist is performed at the temperature and the temperature at which the resist layer enters the recess formed in the mold during imprint. An imprint method characterized in that the method is performed in an atmosphere of a gas condensing at a pressure of 1. 2. The imprint method according to claim 1, wherein a vapor pressure of the gas at a normal temperature is 0.05 MPa or more and 1.00 MPa or less. 2. The imprint method according to claim 1, wherein the gas has a boiling point of 15 to 30 [deg.] C. at atmospheric pressure. In an imprint apparatus including a mold having an irregular shape on the surface, a substrate having a resist layer formed on the surface, and a mold driving device for pressing the mold against the resist layer, at least the mold surface separated from the resist layer An imprint apparatus comprising: a gas supply device for supplying a gas condensed at a temperature and a pressure when a resist layer enters a concave portion formed in a mold at the time of imprint to an imprint operation portion. . 5. The imprint apparatus according to claim 4, wherein in the imprint apparatus, a vapor pressure of the gas at a normal temperature is 0.05 MPa or more and 1.00 MPa or less. The imprint apparatus according to claim 4, wherein the gas has a boiling point of 15 ° C. or more and 30 ° C. or less at atmospheric pressure. The imprint apparatus according to claim 4, wherein the gas supply device supplies the gas so that a closed space has a predetermined pressure. The gas supply device supplies the gas to the imprint portion in an open space, and supplies the gas so as to compensate for dissipation from the imprint portion by diffusion. 5. The imprint apparatus according to 4. 5. The imprint apparatus according to claim 4, wherein the gas supply apparatus supplies the gas to the imprint operation portion so that a gas flow of the gas is generated. 6.

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