JP3700001B2 - Imprint method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In the imprint in which a mold having a predetermined pattern is pressed against a resist layer applied to a substrate surface or a supplied resist, a transfer defect due to an atmosphere forming gas taken in between the mold and the resist is detected. The present invention relates to an imprinting method and an imprinting apparatus for performing the method, which are performed in a gas atmosphere that is condensable at the temperature and pressure during imprinting.
[0002]
[Prior art]
In recent years, downsizing of VLSI devices represented by high-density memories and system LSIs has progressed, and a technology capable of further miniaturization has been demanded. Therefore, lithography (transfer) technology is important in the semiconductor manufacturing process. Sexuality 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 for transferring a pattern by pressing a mold having a predetermined circuit pattern against a sample substrate coated with a resist on its surface, and various methods have been proposed, for example, as shown in FIG. To be done.
[0003]
In FIG. 4, first, as shown in FIG. 4A, a reverse pattern corresponding to a mirror image of the pattern to be transferred is formed on the surface of the mold material 20 by electron beam lithography or the like, whereby a specific uneven shape 21 is formed on the surface. A mold 22 having the following is created. On the other hand, as shown in FIG. 4B, a resist material such as PMMA is applied and cured on a base material 23 such as a silicon substrate on which a pattern is to be formed, thereby forming a resist layer 24.
[0004]
Next, the entire base material 23 provided with the resist layer 24 is heated to about 200 ° C., and the resist layer 24 is slightly softened. In this state, as shown in FIG. 4C, the uneven shape 21 of the mold 22 is arranged at a predetermined position of 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 concavo-convex shape 21, and the resist layer 24 has substantially the same shape as the concavo-convex shape 21, as shown in FIG. 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 imprinting is performed on another part of the base material 23, the mold 22 is moved to the upper part of the part relative to the base material 23 as shown in FIG. The mold 22 is pressed against the resist layer 24 at that portion. Thereafter, the same operation is continuously performed at all predetermined positions on the base material 23, and a predetermined imprint is performed.
[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, a liquid photo-curing resin is applied on the substrate to be transferred, and a mold is formed thereon. A method of forming a concavo-convex pattern of a predetermined shape by pressing the concavo-convex of the liquid, allowing a liquid photo-curing resin to flow into the concavo-convex, transmitting the light through the mold, curing the photo-curing resin, and then removing the mold Has also been proposed.
[0007]
[Patent Document 1]
JP 2001-198979 A [Patent Document 2]
JP 2000-289258 A [Patent Document 3]
Japanese Patent Laid-Open No. 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 performed in an air atmosphere, the air is sandwiched between the mold recess and the resist and the air remains even after pressing, so the mold shape can be accurately transferred. Disappear. 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 is reduced in volume, but remains at this location. At this time, as shown in FIG. 5B, not only the air taken in after compression stays uniformly in the mold recess, but also due to the action of the resin that reduces the flow of the resin and the energy of the resin surface. ) And remains in the concave portion of the mold as a foamed portion 17, 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, and the transfer accuracy is impaired. .
[0009]
As countermeasures, there are a method of performing a process of pressing a mold against a resist by an imprint technique in a vacuum, and a method of reducing the volume of the air taken in by increasing the pressure of pressing the mold. However, the former requires a sturdy vacuum layer that can withstand 1 atm to evacuate the device, and the latter cannot perform high-precision transfer because the mold itself deforms due to the use of a large pressure. It can also cause damage to the mold and substrate material.
[0010]
Therefore, the present invention prevents the transfer accuracy from being deteriorated by taking in the gas forming the imprint work atmosphere even at a relatively low pressure (1 MPa or less) of the mold pressing pressure without using a vacuum in the imprint technique. The main object of the present invention is to provide an imprint method and apparatus utilizing the condensability of gas.
[0011]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 of the present application is directed to an imprint for transferring an imprint formed on a mold to a resist layer coated on a substrate surface or a supplied resist. The imprinting method is performed in an atmosphere of a gas that condenses at a temperature when the resist layer enters the concave portion formed at the pressure and a pressure in the concave portion.
[0012]
The invention according to claim 2 is the imprint method according to claim 1, wherein the vapor pressure of the gas at room temperature is 0.05 MPa or more and 1.00 MPa or less.
[0013]
The invention according to claim 3 is the imprint method according to claim 1, wherein the boiling point of the gas is 15 ° C. or higher and 30 ° C. or lower at atmospheric pressure.
[0014]
According to a fourth aspect of the present invention, there is provided an imprint apparatus comprising: a mold having a concavo-convex shape formed on a surface thereof; a substrate having a resist layer formed on the surface; and a mold driving device that presses the mold against the resist layer. A gas supply device that supplies gas that condenses at a temperature and pressure when the resist layer enters the recess formed in the mold at the time of imprinting to the imprint work part at least on the mold surface that is separated from the resist layer. The imprint apparatus is characterized by comprising the imprint apparatus.
[0015]
The invention according to claim 5 is the imprint apparatus according to claim 4, wherein in the imprint apparatus, the vapor pressure of the gas at room temperature is 0.05 MPa or more and 1.00 MPa or less. Is.
[0016]
The invention according to claim 6 is the imprint apparatus according to claim 4, wherein the boiling point of the gas is 15 ° C. or higher and 30 ° C. or lower at atmospheric pressure.
[0017]
The invention according to claim 7 is the imprint apparatus according to claim 4, wherein the gas supply apparatus supplies the gas so that the 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 due to diffusion from the imprint portion. The imprint apparatus according to claim 4, wherein the imprint apparatus is supplied to the apparatus.
[0019]
The invention according to claim 9 is the imprint apparatus according to claim 4, wherein the gas supply apparatus supplies the gas so that a gas flow of the gas is generated in the imprint work part. It is.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an overall schematic diagram of an embodiment of the present invention. In a work chamber 1, a substrate moving stage 3 is arranged on a surface plate 2 so as to be movable in a horizontal plane. Holds a silicon substrate 6 having a resist layer 5 on its surface. The silicon substrate 6 has a size capable of imprinting a plurality of concave / convex patterns 8 of the mold 7 for transferring to the resist layer 5.
[0021]
On the other hand, the mold 7 is moved up and down in the work chamber 1, and a mold driving stage 9 for pressing the concave-convex pattern 8 on the lower surface of the mold against the resist layer 5 positioned below the mold 7 is fixed. 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 so that the uneven pattern 8 on the lower surface of the mold 7 can be pressed against the resist layer 5. It has become.
[0022]
The work chamber 1 is provided with an exhaust device 11, the discharge-side opening / closing valve 12 is released, a supply-side opening / closing valve 13 described later is closed, and the atmosphere in the work chamber 1 is exhausted by driving the pump. The chamber 1 can be supplied with a condensable gas having a predetermined component 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 chamber has a predetermined pressure set in advance. At this time, the temperature in the work chamber can be adjusted to an appropriate temperature such as 23 ° C. as normal temperature by detecting the temperature in the work chamber with the temperature sensor 16 using a separately provided indoor gas temperature control device. The “condensable gas” referred to here is condensed by the pressure when the resist layer enters the concave portion of the mold and compresses the gas confined in the concave portion during the imprint operation, as will be described later. A gas that can be used.
[0023]
Various condensable gases can be selected. For example, trichlorofluoromethane having a vapor pressure of 0.1056 MPa at room temperature (23 ° C.) can be used. Also, a predetermined amount is supplied so that the pressure is slightly low, for example, about 0.1 MPa. The boiling point of the substance constituting such a condensable gas atmosphere is preferably a temperature close to room temperature of about 15 ° C. to 30 ° C. when the pressure in the working chamber is about 1 atm. However, depending on the type of condensable gas, it is appropriately changed depending on the pressure setting in the work chamber.
[0024]
When the imprinting operation is performed in an atmosphere of such a condensable gas, an appropriate imprinting operation according to the present invention can be performed by the action as shown in FIG. In FIG. 2, a mold 7 having a specific uneven pattern 8 formed on the lower surface is pressed against the surface of a silicon substrate 6 provided with a resist layer 5 on the surface in the same manner as that used in the apparatus of FIG. This shows the initial state in which the printing operation is performed, and shows a state in which the concave / 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 blocked from the outside, and thus the condensable gas 30 in the concave portion 25 is in a sealed state.
[0025]
Thereafter, when the mold 7 is lowered by the mold drive moving stage 9 of FIG. 1, the convex portion 26 of the concave / convex pattern 8 is pushed into the softened resist layer 5 as described above. Break into. Thereby, the condensable gas 30 which is in the sealed state in the concave portion 25 is compressed, and the pressure rises.
[0026]
When the convex portion 26 of the concavo-convex pattern 8 is pushed into the resist layer 5 when the mold 7 is lowered, the convex portion 26 around the outer periphery 27 of the mold 7 surrounds the resist layer 5, so that the resist layer 5 is surrounded by the convex portion 26. Although the inner resist layer 5 partially moves to the outside of the outer periphery 27 of the mold 7 as the mold 7 is lowered, many of the 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 way, the mold 7 is finally pressed until reaching a predetermined pressure of, for example, about 0.5 MPa, and the lower surface thereof reaches the height of the final position in the resist layer 5, for example, as shown in FIG. When entering, the resist layer 5 in the recess 25 further rises in the space and compresses the condensable gas 30 inside. Although the temperature of the condensable gas 30 will naturally rise during this compression process, the volume is extremely small in the field of imprint lithography, the surface area is large, and the heat capacity of the mold 7 is large. As described above, the heat generated in the compression process is removed to the surroundings and is maintained at the same level as the set temperature in the working portion.
[0028]
Since the resist layer 5 that has penetrated deeply into the concave portion 25 of the mold 7 as described above compresses the condensable gas 30 therein, the pressure of the condensable gas increases in proportion to the volume reduction. When the condensable gas used here is selected as a gas that becomes liquid at the time of compression as described above at the temperature of the working part as described above, the condensable gas 30 is compressed in the concave portion 25 as described above. A part of the condensable gas 30 is liquefied.
[0029]
Due to the liquefaction of the condensable gas 30 in the recess 25, the volume varies depending on the gas properties (molecular weight), but the volume of the recess 25 becomes smaller than the vapor pressure of the gas. Kept. Eventually, when the pressure applied to the resist layer 5 is higher than the vapor pressure of the gas, liquefaction of the gas occurs continuously. Finally, all the gas is liquefied, and the resist that has entered the recess 25 as described above. For example, as shown in FIG. 2 (d), the layer 5 is in a state of filling almost the entire space of the recess 25.
[0030]
Thereafter, the mold 7 is raised, and the concavo-convex pattern 8 is separated from the resist layer 5 and the silicon substrate 6 is moved in the horizontal direction by the substrate moving stage 3 in the same manner as shown in FIG. The resist layer 5 to be imprinted next is positioned on the lower surface, and the same operation is performed thereafter.
[0031]
In this way, when the mold 7 is raised and the concave / convex pattern 8 is separated from the resist layer 5, the condensate in the concave portion 25 returns to the original pressure, so that the condensable gas that is gasified again to form the surrounding atmosphere. Mix with.
[0032]
By performing the operation as described above, it is possible to solve the problem that the concavo-convex pattern due to the compressed gas remaining in the concave portion cannot be accurately transferred as in the conventional imprint shown in FIG.
[0033]
As described above, in the present invention, the imprinting operation can be performed in an atmosphere where a condensable gas having a predetermined property exists in the surrounding area, but the conventional problem can be solved. For example, the working chamber 1 in FIG. 1 can be used as a closed space and filled with a condensable gas having a predetermined property, and this operation can be performed therein. In that case, a means for controlling the pressure and temperature so as to maintain the inside of the working chamber at a predetermined pressure and at a predetermined temperature may be provided.
[0034]
Further, the above-described imprint work can be performed in a relatively large work space in a state where the normal atmosphere exists therein, and the above-described portion of the imprint work is performed as 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 diffuses to the surroundings, so that the amount of the dissipated condensable gas is replenished from the gas supply device.
[0035]
In addition, when the work chamber is a closed space as described above, and when the work space is almost atmospheric, a condensable gas supply device is provided that can always generate a condensable gas flow to the part where imprint work is performed. The imprint operation may be performed in such a condensable gas flow.
[0036]
As described above, the condensable gas that forms the atmosphere of the imprint work part uses a gas that condenses at least the pressure when the inside of the recess 25 of the mold 7 is finally compressed during the imprint work. . In this case, various condensable gases can be used. For selection of the condensable gas, for example, selection is made with reference to the condensation curves of various gases as shown in FIG.
[0037]
In the condensation curves of various gases shown in FIG. 3, for example, as is apparent from the condensation curve of water vapor shown in the lower right of the figure, the water is condensed at 100 ° C. to become water at an atmospheric pressure of 0.1013 MPa. However, it condenses into water at a lower pressure at a low temperature, and conversely becomes water at a higher pressure at a high temperature. 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 is condensed at about 20 ° C. It can be seen that when the pressure is increased to 2 MPa, condensation occurs at about 40 ° C. Similarly, it can be seen that the gas (gas such as refrigerant R12) shown as C2 in the figure liquefies at about 0.5 MPa at 20 ° C. and liquefies at 1 MPa at 40 ° C.
[0038]
Since the pressure increases in proportion to the volume when the temperature of the gas is constant (P × V / T = constant), for example, the concave / convex pattern 8 of the mold 7 is pressed against the resist layer 5 as shown in FIG. When the resist layer 5 enters and the volume of the condensable gas 30 in the recess 25 is reduced to 1/2, the pressure of the condensable gas is doubled, and when the volume is reduced to 1/3, the pressure of the condensable gas is reduced. Is tripled. Accordingly, a condensable gas that is a gas in the pressure state of the working chamber is selected such that it is compressed as described above and is condensed in a state in which the volume decreases and the pressure increases.
[0039]
For example, when the gas C1 in FIG. 3 is used as the condensable gas, when the imprint operation is performed with the working chamber at atmospheric pressure and the working portion at 40 ° C., the vicinity of the recess 25 is also approximately 40 ° C. Shortly before the inside of the concave portion 25 is reduced to ½, the condensable gas 30 therein condenses. Similarly, when the working portion is at 30 ° C. and atmospheric pressure, when the pressure in the recess 25 becomes about 0.15 MPa, that is, when the volume of the recess 25 decreases by about 1/3, that is, 2/3 of the initial volume. When it reaches a degree, it will condense and liquefy.
[0040]
Further, for example, when the gas C2 in FIG. 3 is used as the condensable gas, when the imprinting operation is performed at 20 ° C. and 0.2 MPa, the resist layer 5 enters the recess 25 and the volume is 1 /2.5, and when the internal pressure is about 0.5 MPa, condensation occurs. Therefore, the present invention can be carried out using such a gas C2, but if the temperature of the working part is to be carried out at the atmospheric temperature, the working chamber must always be raised to about 0.2 MPa or higher. In other words, the work room equipment must be expensive. On the other hand, when the water vapor in FIG. 3 is used, if the operation is to be performed at a room temperature of about room temperature, the operation must be performed at a very low pressure, and the temperature in the other work chamber is set to 100 ° C. or higher. For example, the equipment related to the work room must be large.
[0041]
As described above, although various condensable gases can be used in the present invention, it is preferable that the working chamber is at room temperature and at atmospheric pressure as much as possible in consideration of equipment costs and the like. As a widely used gas, a condensable gas capable of performing the above operation at a pressure of about 0.05 MP to 1 MP at room temperature (23 ° C.) or a large temperature near room temperature (15 ° C. to 30 ° C.). It is preferable to use a condensable gas having the same vapor pressure as 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 condensable gas, bubbles taken in even at an imprint pressure of several atmospheres can be almost eliminated, and accurate imprint can be easily performed at atmospheric pressure. In addition, it can be performed with an inexpensive apparatus.
[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 operating state when imprinting is performed in a condensable gas atmosphere according to the present invention.
FIG. 3 is a condensation curve showing an aspect in which various gases are condensed by changes in ambient temperature and pressure.
FIG. 4 is a schematic diagram illustrating an imprint process.
FIG. 5 is a schematic diagram showing a problem in a conventional imprint operation.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Work chamber 2 Surface plate 3 Base material moving stage 5 Resist layer 6 Silicon substrate 7 Mold 8 Uneven pattern 9 Mold drive stage 10 Mold pressing mechanism 11 Exhaust device 12 Discharge side opening / closing valve 13 Supply side opening / closing valve 15 Condensable gas supply device

Claims (9)

The temperature at which the resist layer intrudes into the recess formed in the mold during imprinting and imprinting the imprint shape formed on the mold onto the resist layer applied on the substrate surface or the supplied resist. Imprinting method characterized by performing in the atmosphere of the gas condensed with the pressure of. The imprint method according to claim 1, wherein the vapor pressure of the gas at normal temperature is 0.05 MPa or more and 1.00 MPa or less. The imprint method according to claim 1, wherein the boiling point of the gas is 15 ° C or higher and 30 ° C or lower at atmospheric pressure. In an imprint apparatus comprising a mold having a concavo-convex shape formed on a surface, a base material having a resist layer formed on the surface, and a mold driving device for pressing the mold against the resist layer, the mold surface at least separated from the resist layer In contrast, the imprint apparatus includes a gas supply device that supplies a gas that condenses at a temperature and a pressure when the resist layer enters the recess formed in the mold during imprinting to the imprint work part. . 5. The imprint apparatus according to claim 4, wherein the vapor pressure of the gas at normal temperature is 0.05 MPa or more and 1.00 MPa or less. The imprint apparatus according to claim 4, wherein the boiling point of the gas is 15 ° C. or higher and 30 ° C. or lower at atmospheric pressure. The imprint apparatus according to claim 4, wherein the gas supply apparatus supplies the gas so that the 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 due to diffusion from the imprint portion. 4. The imprint apparatus according to 4. The imprint apparatus according to claim 4, wherein the gas supply apparatus supplies the gas so that a gas flow of the gas is generated in the imprint work part.

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