WO2008056558A1

WO2008056558A1 - Method of imprinting

Info

Publication number: WO2008056558A1
Application number: PCT/JP2007/070998
Authority: WO
Inventors: Hiroshi Miyakoshi; Masahiro Morikawa
Original assignee: Konica Minolta Holdings, Inc.
Priority date: 2006-11-07
Filing date: 2007-10-29
Publication date: 2008-05-15
Also published as: JPWO2008056558A1

Abstract

A method of imprinting in which deformation or breaking of microstructures having been transferred by thermal imprinting during die parting process can be avoided. In this method of imprinting, a heated die is brought into contact under pressure with an imprinting object and parted therefrom to thereby transfer a microstructure provided in the die to the imprinting object. In the method, the relationships of the formulae Tg<Tr≤Tt-3 and Vr≤2 are satisfied, wherein Tt refers to transfer temperature being a temperature at pressure contact of die (°C), Tr to die parting starting temperature being a temperature at starting of die parting (°C), Tg to glass transition temperature of imprinting object (°C), and Vr to relative parting speed between die and imprinting object at the parting thereof (mm/sec).

Description

Specification

Imprint method

Technical field

TECHNICAL FIELD [0001] The present invention relates to an imprint method for transferring a microstructure provided in a mold onto a molding material by releasing the heated mold after being pressed against the molding material.

Background art

[0002] After a resin such as polystyrene is pressure molded using a mold having a microstructure, the molded product is peeled off from the mold and released to obtain a microstructure having a micro uneven pattern. A printing method is known (for example, see Patent Document 1 below).

Patent Document 1: JP-A-2005-189128

Disclosure of the invention

Problems to be solved by the invention

[0003] However, according to the conventional method, in the above-mentioned mold release, when the molded product is cooled to the glass transition point temperature Tg or less of the molding material, the peeling force s, in such mold release, Due to the difference in thermal shrinkage between the mold and the molded product, the fine structure pattern may break, and the yield of imprint molding will be reduced. In particular, in the case of a periodic fine structure having a large aspect ratio, the fine structure pattern is more easily broken.

The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide an imprint method in which a microstructure transferred by thermal imprint is prevented from being deformed and destroyed by a mold release process. .

Means for solving the problem

In the thermal imprint method, after a mold having a heated microstructure is pressed against a material to be molded, cooling and solidification are performed for the purpose of maintaining the molded fine shape. In most cases, the linear expansion coefficient of the molded material is different, so a relative shift occurs in the microstructure due to the difference in thermal shrinkage. When the transfer area is large, this deviation amount becomes large. To solve this problem, the temperature at the time of mold release was brought close to the molding temperature (Tg or more). However, the material to be molded has a high temperature! The problem of end.

[0006] As a result of intensive studies to solve both of the above problems, it has been found that the above problem of deformation can be solved by performing the mold release speed at a low speed, and the present invention has been achieved.

That is, the imprint method according to the present invention transfers a microstructure provided in the mold to the molding material by releasing the mold after pressing the heated mold against the molding material. In this method, the temperature of the mold when press-contacting the mold is the transfer temperature Tt [° C], the temperature of the mold when starting the mold release is the mold release start temperature Tr [° C], When the glass transition temperature of the molding material is Tg [° C] and the relative separation speed between the mold and the molding material is Vr [mm / sec], the following conditions are satisfied. It satisfies the expressions (1) and (2).

Tg <Tr≤Tt- 3 (1)

0. 001≤Vr≤2 (2)

According to this imprinting method, the mold release start temperature Tr exceeds the glass transition temperature Tg of the molding material and is at least 3 ° C lower than the transfer temperature Tt, and the separation speed Vr is 0.001 mm / More than 2 seconds and 2 mm / second or less, the microstructure transferred to the molding material is deformed by the mold release process.

Since the range of Tr becomes relatively wide, it becomes easy to control the mold temperature during mold release.

[0008] The reason for setting the mold release speed to Vr ≤ 2 [mm / sec] is as follows. That is, a stress is generated in the fine structure portion with respect to the force for releasing the mold due to the contact resistance in the fine structure portion of the mold and the molding material. At this time, if the mold release speed is high, the stress rapidly increases, and if the mold is released at Tg or higher, the material to be molded is likely to be plastically deformed (permanently deformed), so that stretch deformation remains in the mold release direction. Therefore, in the present invention, the mold release speed is reduced in order to generate only the force necessary for mold release without increasing the mold release resistance, that is, the mold release speed Vr is set to Vr≤ 2 [mm / sec. ]

Furthermore, the reason for setting the release speed Vr to Vr≥0.001 [mm / sec] is as follows. In other words, if the mold release speed is less than 0.001 [mm / sec], the mold release speed is too slow, and plastic deformation occurs at the base of the microstructure between the microstructure and the material to be formed. This is because there is a problem that the base of the structure extends or breaks. In the imprint method, it is preferable that the following conditional expression (3) is further satisfied.

Tr> Tt-15 (3)

In addition, it is preferable to satisfy the following conditional expression (4), and it is preferable to fill the microstructure of the molding material.

Tt≥Tg + 20 (4)

The fine structure is a periodic structure having a period T, a structure height Η, and a structure width L, the period Τ being 2 m or less, and an aspect ratio (H / L) of the periodic structure after transfer. Is preferably 2 or more. By applying the above imprinting method, it is difficult to form with the conventional method, and a fine periodic structure with an aspect ratio (H / L) of 2 or more is not deformed or destroyed by a release process. Can be transferred to the molding material.

[0010] Further, the molding material is preferably made of a resin material! The mold may be Si, Si 2 O, Ta, Ni, NiP, glassy carbon (C), polycarbonate, or plastic.

It is preferable to be made of silicon-based resin.

The invention's effect

[0011] According to the imprinting method of the present invention, the microstructure transferred by thermal imprinting is difficult to be deformed and destroyed by the release process. For this reason, the yield is improved and the productivity of the molded product is improved.

Brief Description of Drawings

FIG. 1 is a diagram schematically showing a main part of an imprint apparatus capable of executing an imprint method according to the present embodiment.

2 is a diagram schematically showing a configuration example of a release driving device 23 in FIG. 1. FIG.

3 is a flowchart for explaining molding steps S01 to S07 by the imprint apparatus 10 of FIGS. 1 and 2. FIG.

FIG. 4 is a side cross-sectional view schematically showing a part of a repeated concavo-convex microstructure formed in a molding die of this example.

[Fig. 5] Optical micrographs of the molding materials when the release start temperature Tr [° C] is 132, 100 and the separation speed Vr is 10 mm / sec in this example and the comparative example. a), (b), mold release start temperature Tr [° C] is 132, 135, 130, and separation speed Vr is 10 mm / sec. (C), (d), and (e) are scanning electron micrographs of each molding material.

FIG. 6 is a diagram showing the relationship between the mold release start temperature and the transfer area ratio in Examples and Comparative Examples.

FIG. 7 is a diagram showing the relationship between the filling structure height and the transfer temperature in this example.

Explanation of symbols

[0013] 10 imprint apparatus

18 Mold

18a Irregular microstructure

19 Molded material

H Structure height

L Structure width

H / L aspect ratio

T period

Tg Glass transition temperature

Tr release start temperature

Tt Transfer temperature

Vr Separation speed

m Press direction

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a diagram schematically showing an imprint apparatus capable of executing the thermal imprint method according to the present embodiment.

As shown in FIG. 1, an imprint apparatus 10 includes a press driving apparatus 11 for an imprint press, and a molding die 18 having a concavo-convex microstructure 18a in which fine undulations are periodically formed. A supporting part 17 for supporting and fixing, a holding part 20 for holding and fixing a molding material 19 of a resin material which is molded relatively close to the molding die 18, and a driving part 20 for releasing the mold. A mold driving device 23, a force sensor 22 arranged between the holding unit 20 and the mold release driving device 23 for detecting the force applied to the molding material 19, and an amplifier 2 for amplifying the detection signal from the force sensor 22 4 and feedback control of the mold release drive device 23 based on the amplified detection signal from the amplifier 24, and a control unit 25 for controlling the transfer temperature and the mold release start temperature of the molding die 18. Prepare.

[0016] The press drive device 11 is supported by being connected to the servo motor 12, the press mechanism unit 13 that performs the press by converting the rotational motion of the servo motor 12 into a linear motion using a ball screw, and the press mechanism unit 13. A drive rod 14 that drives the portion 17 up and down, and presses the molding die 18 and the molding material 19 relatively close to each other.

[0017] The imprint apparatus 10 includes a horizontal member 15a that supports the support portion 17 so as to be movable up and down, a horizontal base 15b that supports and fixes the release drive device 23, and a horizontal base 15b that is fixed to the horizontal base 15b and supports the horizontal member 15a. And a longitudinal member 16.

[0018] Further, the imprint apparatus 10 includes a heater 17a as a heating means for heating the molding die 18 in the support portion 17, and the heater 17a is controlled by the control unit 25 and is used for pressing. 18 is raised to the transfer temperature Tt and held, and is held at the release start temperature Tr for release. Further, a temperature sensor 18b is disposed in the vicinity of the molding die 18, and the temperature of the molding die 18 is detected by the temperature sensor 18b.

[0019] The molding die 18 is preferably made of Si, SiO, Ta, Ni, NiP, glassy carbon (C), polycarbonate, or a fluorine-based resin. For Si and SiO, semiconductor fabrication techniques can be used to form fine patterns, and processing is easy. Ta and glassy carbon (C) have high heat resistance and are characterized by excellent durability when used as a mold. Since Ni and NiP can be used to produce molds by using a method of electric field fitting, it is easy to apply a technique in which a mold is prepared by a technique that facilitates processing of a fine structure separately and plating is used. Polycarbonate has the advantage of facilitating mold replication. A cooling means (not shown) for cooling the molding die 18 is provided in the vicinity of the molding die 18. The molding material is preferably a thermoplastic material such as glass, PMMA, polyolefin resin, polycarbonate, polystyrene, thermoplastic polyimide!

FIG. 2 schematically shows a configuration example of the mold release driving device 23 of FIG. The mold release drive unit 23 shown in FIG. 2 includes the servo motor 31, the ball screw rotating shaft 32 connected to the servo motor 31 and driven to rotate, and the ball screw rotating shaft 32 and the ball screw rotating shaft 32. Up The linear motion part 33 that converts to the linear motion below, the drive base 34 that is driven by the linear motion part 33 via the linear motion bearing 33a, and the drive base 34 are supported via the linear motion bearing 36. And a support member 35 fixed to the horizontal base 15b. The force sensor 22 shown in FIG. In FIG. 2, the drive base 34 is restrained in the horizontal direction by the linear motion bearing 36, and the error motion in the horizontal direction of the ball screw rotating shaft 32 is absorbed by another linear motion bearing 33a. For this reason, only the vertical force of the servo motor 31 and the ball screw rotating shaft 32 is transmitted to the drive base 34, and the drive base 34 can be moved in the vertical direction.

[0021] The servo motor 31 of the mold release drive device 23 of FIG. 2 has a smaller disassembly angle than the servo motor 12 of the press drive device 11 of FIG. The pitch is shorter than the screw. In this way, the mold release drive device 23 has a fine drive resolution! / And constitutes a fine movement mechanism! /. The control unit 25 controls the amount of rotation of the servo motor 31 based on the detection signal of the force sensor 22, so that the molding material 19 on the drive base 34 can be moved at a pitch smaller than the pitch of the press drive device 11. It can be moved on the axis in the pressing direction m and can be separated from the molding die 18 at a relatively low speed (for example, about several m / second). At the time of releasing, the molding die 18 and the workpiece 19 The relative separation speed Vr can be controlled to 2mm / sec or less.

On the other hand, the press drive device 11 shown in FIG. 1 moves the molding die 18 on the axis in the pressing direction m at a relatively large pitch by the servo motor 12 and the press mechanism unit 13 whose driving resolution is coarse. be able to. The material 19 can be approached at a relatively high speed.

[0023] According to the imprint apparatus 10 of FIGS. 1 and 2, when pressing, pressing is performed with the press driving device 11 bringing the molding die 18 closer to the molding material 19 in a relatively short time. Can

Thereafter, at the time of mold release, the material to be molded 19 can be separated from the mold 18 for a relatively long time by the mold release driving device 23 and peeled off.

Next, the molding steps S01 to S07 by the imprint apparatus 10 of FIGS. 1 and 2 will be described with reference to the flowchart of FIG.

[0025] Under the control of the control unit 25 in FIG. 1, the molding die 18 in FIG. 1 is heated by energizing the heater 17a in the support unit 17 to increase the temperature (S01). The temperature is detected by the temperature sensor 18b, and when the mold 18 reaches a predetermined transfer temperature Tt (eg, 135 ° C) (S02), the press The servo motor 12 of the drive unit 11 is driven to rotate, and the drive rod 14 is fast-forwarded in the press direction m below in the figure by the press mechanism 13 in a relatively short time to bring the molding die 18 close to the workpiece 19 Then, the molding die 18 is pressed against the material 19 to be pressed (S03), held for a predetermined time with a predetermined pressing force (S04), and then the molding die 18 is cooled (S05).

[0026] Next, when the temperature of the molding die 18 decreases by at least 3 ° C from the transfer temperature Tt and reaches the release start temperature Tr (eg 132 ° C) (S06), the release drive device 23 of FIG. The servomotor 31 is driven to rotate, and the molding material 19 is moved downward by means of the ball screw rotating shaft 32 via the linear motion part 33 and the drive base 34, and the mold is molded at a relative separation speed Vr of 2 mm / sec or less. Release from 18 and release (S07). Thereby, the periodic uneven microstructure 18 a of the molding die 18 is transferred to the molding material 19. The mold release start temperature Tr is a temperature higher than the glass transition temperature Tg (for example, 101 ° C.) of the resin material of the molding material 19.

[0027] According to the imprint method described above, the above conditional expressions (1) and (2) are satisfied, the mold release start temperature Tr exceeds the glass transition temperature Tg of the resin material of the molding material 19, and the transfer temperature Tt In addition to being 3 ° C lower than that, and slowly performing mold release at a separation speed Vr of 2 mm / sec or less, the uneven microstructure transferred to the molding material 19 is deformed and destroyed in the mold release process (S07). It becomes difficult. Further, by setting the separation speed Vr to 2 mm / second or less, a preferable range of the mold release start temperature Tr is widened, and the temperature of the molding die 18 at the time of mold release can be easily controlled.

[0028] It is preferable that the mold release start temperature Tr [° C] further satisfies the condition of Tr> Tt-15 in the conditional expression (3) with respect to the transfer temperature Tt [° C]. Further, it is preferable that the transfer temperature Tt [° C.] satisfies Tt≥Tg + 20 in the above conditional expression (4) with respect to the glass transition temperature Tg [° C.] of the resin material of the molding material 19.

Example

[0029] Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the examples.

The molding die has a periodic uneven microstructure as shown in Fig. 4 (structure height H: 1200 nm, structure width L: 200 nm, periodicity in a circular area of lmm diameter in the center of a 0.5 mm thick silicon substrate. T: 400 nm, aspect ratio H / L: 6). From PMMA as molding material A transparent resin sheet (glass transition temperature Tg: 101 ° C) was used, and the mold transfer temperature Tt was set to 135 ° C.

[0031] By using the same imprint apparatus as in FIGS. 1 and 2 and combining the disassembly angle of the servo motor and the pitch of the ball screw in the mold release drive unit, the minimum feed resolution of the fine movement mechanism is 0.01 m, The minimum feed rate by the fine movement mechanism was set to 0.2 m / sec. The minimum feed resolution of the press drive device was 10 H m, the feed rate was 10000 H m / sec, the press force was 400 N (pressure about 4 MPa), and molding was carried out for 2 sec.

Next, the mold release process was performed under the conditions shown in Table 1 below. That is, mold release temperature Tr

[° C] is 132 (Example 1), 130 (Example 2), 125 (Example 3), 120 (Example 4), 110 (Example 5), and for each mold release start temperature Tr, The mold release was performed with the relative separation speed Vr [mm / sec] for separating the molding die and the material to be molded set to 2, 1, 0.01 and 0.001.

[0033] <Comparative Example;! ~ 4>

As a comparative example, as shown in Table 1 below, the examples are the same except that the release temperature Tr [° C] is 135 (Comparative Example 1), 13 3 (Comparative Example 2), and 100 (Comparative Example 3). Molding and mold release were carried out under the same conditions as in. In addition, for each of the above mold release start temperatures Tr (135, 133, 132, 130, 125, 120, 110, 100 ° C), mold release was performed at a relative separation speed Vr of 10 mm / sec (Comparative Example 4). Except for the above conditions, molding and mold release were performed under the same conditions as in the example.

[0034] [Table 1]

Table 1 shows the observation results for the molding materials after the above-mentioned molding and release. From the results of Examples;! To 5, in the temperature range where the release temperature Tr is at least 3 ° C lower than the transfer temperature Tt (135 ° C) and exceeds the glass transition temperature Tg (101 ° C), And the separation speed Vr is 2mm / If it is less than 2 seconds, it can be seen that the material to be molded does not break or excessively deform when releasing (see Fig. 5 (c)).

[0036] On the other hand, from the results of Comparative Examples 1 to 4, when the mold release start temperature Tr is 135 ° C and 133 ° C where the temperature difference is less than 3 ° C from the transfer temperature Tt, the transferred uneven microstructure is It was greatly deformed (see Fig. 5 (d)), and when it was 100 ° C below the glass transition temperature Tg, a part of the transferred concavo-convex microstructure was broken (Fig. 5 (e) )reference). In addition, when the separation speed Vr was as fast as 10 mm / sec, a force that was good when the mold release start temperature Tr was 132 ° C. Under these conditions, large deformation or fracture occurred.

[0037] FIGS. 5 (a) and 5 (b) show the case where the release temperature Tr [° C] is 132, 100 and the separation speed Vr is 1 Omm / sec (Comparative Example 4). An optical micrograph of the workpiece is shown (the diameter of the circular part is lmm). Figures 5 (c), (d), and (e) show that the mold release temperature Tr [° C] is 132, 135, 130 and the separation speed Vr is 10 mm / sec (Comparative Example 4). Scanning electron micrographs of the molding materials are shown. When the separation speed Vr is as fast as 10 mm / sec when the mold release, the mold release start temperature Tr is 132 ° C, except when the mold release start temperature Tr is 132 ° C, as shown in Fig. 5 (d). If Tr is too high, the concavo-convex microstructure will be greatly deformed. As shown in FIG. 5 (e), if the release temperature Tr is too low, a part of the concavo-convex microstructure will be broken.

Next, the transfer area ratio [%] was measured for the molding material when the separation speed Vr [mm / sec] was set to 0.01, 2, and 10 in the above examples and comparative examples. The transfer area ratio is expressed as a percentage of the transfer target area of the area where the concavo-convex fine structure is transferred. Regarding the defect ratio [%] in Table 1, the defect ratio [%] = 100—transfer area ratio [%]. . Figure 6 shows the relationship between the release start temperature [° C] and the transfer area ratio [%]. As can be seen from FIG. 6, when the separation speed Vr is 0.01 and 2 mm / second, the transfer area ratio becomes 90% or more when the mold release start temperature is 110 ° C or more, and 120 to 132 ° C. In the range of 1, that is, the mold release start temperature Tr that satisfies the above conditional expression (3) (temperature exceeding 15 ° C lower than the transfer temperature Tt, that is, temperature exceeding 120 ° C), it is close to 100% When the force becomes 133 ° C or more, the transfer area ratio decreases rapidly.

[0039] From the results of Figs. 5 (a) to (e), the mold release temperature Tr exceeds the glass transition temperature Tg and is less than the transfer temperature Tt. Further, from the results of Table 1 and Fig. 6, If the transfer temperature Tt is at least 3 ° C lower and the separation speed Vr is 2 mm / second or less, the molded material will break or break during mold release. It can be seen that excessive deformation does not occur.

[0040] Further, when the separation speed is 10 mm / sec, breakage and excessive deformation do not occur! / The range force of the mold release start temperature is narrow at only one point of 32 ° C, whereas the separation speed Vr is It can be seen that when it is 2 mm / sec or less, the effective mold release temperature Tr range in which breakage or excessive deformation does not occur becomes as wide as 110 to 132 ° C. As described above, since the mold release can be performed in a relatively wide temperature range, the mold temperature during the mold release can be easily controlled.

Next, the effect of the transfer temperature Tt on the filling height of the uneven microstructure was investigated. Except for using a molding die with a structural height of 980 nm, a period of 400 nm, and a structural width of 200 nm as shown in FIG. 7, the transfer temperature Tt was set to 105, 115, 125, 135, 145, 155. Molding and mold release were performed under the same conditions as in 5. The separation speed Vr at the time of mold release was set to lmm / second. Fig. 7 shows the relationship between the measured filling structure height and the transfer temperature. The height of the filling structure of the uneven microstructure transferred to the molding material was measured. As can be seen from FIG. 7, the higher the transfer temperature Tt exceeds the glass transition temperature Tg (101 ° C), the better the filling property, and the best filling property is at 135 ° C, and it exceeds 135 ° C. Also has good fillability. If the transfer temperature Tt is 120 ° C, the height of the filling structure is 400 nm, and the aspect ratio after transfer 2 is satisfied. That is, if the resin material is at least 20 ° C higher than the glass transition temperature Tg (101 ° C), the aspect ratio after transfer is 2 or more.

[0042] As described above, the best mode for carrying out the present invention has been described. The present invention is not limited to these, and various modifications are possible within the scope of the technical idea of the present invention. . For example, the resin material used in the examples and comparative examples is an example, and other resin materials may be used. Of course, the glass transition temperature differs depending on the material. ), (3), and (4), appropriate release start temperature and transfer temperature are set for each material.

Further, the imprint apparatus is not limited to the one shown in FIGS. 1 and 2, and any imprint apparatus may be used as long as the separation speed at the time of mold release can be controlled to 2 mm / second or less.

Claims

The scope of the claims

[1] An imprint method in which a microstructure provided in the mold is transferred to the molding material by releasing the heated mold after being pressed against the molding material,

The mold temperature when pressing the mold is the transfer temperature Tt [° C], the mold temperature when starting the mold release is the mold release start temperature Tr [° C], and the glass of the molding material Assuming that the transition temperature is Tg [° C] and the relative separation speed between the mold and the molding material is Vr [mm / sec], the following conditional expression (1) and An imprint method characterized by satisfying (2).

Tg <Tr≤Tt- 3 (1)

0. 001≤Vr≤2 (2)

[2] The imprint method according to claim 1, further satisfying the following conditional expression (3):

Tr> Tt-15 (3)

[3] The imprinting method according to claim 1 or 2, further satisfying the following conditional expression (4):

Tt≥Tg + 20 (4)

[4] The microstructure is a periodic structure having a period T, a structure height Η, and a structure width L, and the period Τ is 2 ^ 111 or less,

The imprint method according to any one of claims 1 to 3, wherein the aspect ratio of the periodic structure after transfer (H / U is 2 or more).

[5] The imprint method according to any one of [1] to [4], wherein the molding material is made of a resin material.

[6] The die according to any one of claims 1 to 5, wherein the mold is made of Si, SiO, Ta, Ni, NiP, glassy carbon (C), polycarbonate, or a fluororesin. The imprint method described.