JP2005268675A - Miniature pattern forming apparatus and semiconductor device manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To propose a nano-imprint device capable of exerting a uniform pressing pressure even at a shot around a wafer and of achieving a highly precise transfer pattern. <P>SOLUTION: The entire surface of the mold pattern is pressurized by providing a board flush with a wafer at a part (outer periphery of the wafer) where a mold does not oppose the wafer. Alternatively, a uniform pressing is achieved by controlling pressurization such that the center of gravity during pressurization is positioned inside the region where the mold actually opposes the wafer. For the latter case, more specifically, a plurality of pressurization points are provided to control pressurization power independently, or a means for moving the center of gravity during pressurization is provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fine pattern forming apparatus for transferring a pattern on an original disk by pressing it onto a substrate to be processed, and a semiconductor device manufacturing method using the same, and more particularly to improvement of control of a transfer pattern size around a wafer substrate. .

  In recent years, the pattern line width of an integrated circuit has been reduced with the increase in the density and speed of a semiconductor integrated circuit, and the semiconductor manufacturing method has been required to have higher performance. In particular, pattern formation that requires particularly high precision is an ultra-high-tech alternative to the method of forming a pattern on a semiconductor substrate by causing a chemical reaction by resist exposure by irradiation with charged particle beams such as ultraviolet rays, X-rays, or electrons and ions. Nanoimprint lithography has been proposed in which a pattern is formed by leaving an impression on a resist or a substrate itself by pressing a hard mold having a fine uneven pattern (see, for example, Patent Document 1). Nanoimprinting can be expected as a technology that overcomes both the resolution limit due to the wavelength of exposure light and the lack of throughput that is a problem in direct drawing. This prior art will be described with reference to FIG.

  In FIG. 9-a, the mold 10 has a mold pattern 11 as a master on a mold table 12. On the substrate side, a resist 21 for patterning is applied on the wafer 20.

  Next, the nanoimprint process will be described. The mold 10 and the wafer 20 are opposed to each other as shown in FIG. 9A, and the mold 10 is moved (pressed) in the direction indicated by the arrow 90 as shown in FIG. 9B. The drawn pattern is transferred onto the resist 21. Then, when the mold 10 is released from the resist 21, unevenness that is inverted according to the unevenness of the mold pattern 11 is formed in the resist 21 as shown in FIG. 9-c. Thereafter, the resist of the remaining film portion 22 is removed by reactive ion etching (RIE), and patterning as shown in FIG. 9-d can be performed.

The above is a basic process common to pattern formation, and thereafter, each process process such as base etching and lift-off is performed using the 9-d resist film as a mask (not shown).
US Patent 5,772,905 JP2003-077867 Special Table 2003-516644

  Pattern size uniformity within a single processing region (hereinafter referred to as a shot) in pattern generation, including nanoimprinting, is an important requirement. In general, in nanoimprinting, it is known that the pressure uniformity over the entire surface of the mold 10 affects the pattern size uniformity of the transferred image. FIG. 10 shows an example in which the pattern size uniformity deteriorates. In FIG. 10-2, if the pressure applied to the mold 10 is different on the left and right (90-L, 90-R), the pressing direction is 90 ', and as a result, the mold is inclined and pressed against the wafer surface. Therefore, there is a difference in the thickness of the resist remaining film portion 22 in the shot as shown in FIG. 10-3, and when the resist of the remaining film portion 22 is removed by subsequent RIE, a pattern with uneven dimensions as shown in FIG. Become. Measures for uniformly pressing have been proposed (see, for example, Patent Documents 2 and 3). FIG. 11 is an example of Patent Document 2, and the mold 10 and the wafer are moved so that the desired shot positions of the mold 10 and the wafer are on the upper surface of the support 1102 provided with the tilt adjusting mechanism 1101, and as shown in FIG. Even when they are relatively inclined, they are parallel to each other, and a uniform pressing pressure can be applied to the resist. FIG. 12 shows an example of Patent Document 3, in which the mold 10 is formed of a flexible membrane 1201 on one surface of the cavity 1202, and the mold 10 is placed on the membrane and the fluid pressure in the cavity 1202 is adjusted. A uniform force can be applied to the entire surface. For example, a uniform pressing force can be applied to a wafer having a wedge component as shown in FIG. 12-c.

  However, the wafer area is larger than the transfer area of the mold 10, and the range that can be transferred by pressing the mold once (that is, the shot) is a part of the wafer. Transfer (mold pressing) and transfer to transfer the pattern to the entire wafer surface It is necessary to shift the position, so-called step and repeat. FIG. 8 shows an example of a shot layout. What should be noted here is that peripheral shots in which the entire surface cannot be completely transferred are also transferred in order to reduce the manufacturing cost of the device to be created and to eliminate process processing unevenness. (Assuming that multiple devices (chips) are arranged in a matrix in one shot). That is, the mold 10 means pressing even when the entire transfer area is not completely opposed to the wafer. The pressing state of the peripheral shot is shown in FIG. Even if it is controlled so that a uniform force is applied to the entire mold surface, the pressure 90-R is also applied to the portion 1301 that is not facing, so the pressing direction is 90 ", and the mold is tilted with respect to the wafer surface. Therefore, as shown in Fig. 13-c, the difference in the thickness of the resist remaining film portion 22 occurs in the shot as in the case of non-uniform pressing, and the resist of the remaining film portion 22 is caused by subsequent RIE. 13-d, the pattern is not uniform in size as shown in Fig. 13-d.If there is no opposing surface as shown in Fig. 11-c in the previous patent document 2, the tilt adjustment mechanism 1101 moves the mold 10 and the resist surface together. In addition, Patent Document 3 does not disclose transfer related to the step-and-repeat method, and does not assume transfer only to the peripheral portion.

  In view of the above-described problems of the conventional technology, the present invention is a step-and-repeat nanoimprint method, which applies a uniform pressing pressure to shots on the peripheral portion of a wafer and improves the transfer pattern accuracy.

  In order to solve the above problems, the first invention of the present application is arranged on a wafer stage so as to be substantially concentric with the held wafer at the same height as the wafer surface when the wafer is held. It has a ring-shaped structure, and the entire mold surface faces even when the mold is pressed to the periphery of the wafer. In the second invention, the ring-shaped structure is disposed on the wafer stage via a spring and a damper, and when the mold is opposed to the periphery of the wafer, the area facing the wafer and the ring-shaped structure are opposed. It is characterized in that the elastic force is controlled so that no pressure difference is generated between the two regions. The third invention is characterized in that the pressing mechanism for the mold has a pressing point at each vertex of at least three or more polygons substantially including a region that can be opposed. According to a fourth aspect of the invention, there is provided a pressurizing point control mechanism for controlling the pressure applied to each pressurizing point so that the pressurizing center of gravity comes to the inside of the actually opposed region. According to a fifth aspect of the present invention, there is provided a pressurizing mechanism moving means capable of moving the pressurizing mechanism in a direction in the opposed plane, and the pressurizing mechanism moving means so that the pressurizing mechanism is located inside the actually facing region. It is characterized by driving.

  According to the present invention, when the mold pattern is transferred to the peripheral shot of the wafer, the mold pattern surface and the wafer are not opposed to each other so that the same height plate faces the entire surface of the mold pattern surface. By applying pressure control so that pressure is applied, or the center of gravity applied to the mold is located within the area where the mold and wafer are actually facing each other, uniform pressing is possible and high-precision pattern transfer is realized. it can.

  Several examples suitable for the present invention will be described below.

  FIG. 2 shows a schematic configuration of a nanoimprint apparatus according to an embodiment of the present invention.

  The nanoimprint apparatus main body 30 is entirely covered with a chamber 31 to maintain a constant atmosphere inside the apparatus. The gantry 32 has a highly rigid structure, and enables the wafer 20 and the mold 10 to be positioned with high accuracy. The mold 10 is conveyed and held by the mold chuck 33 from the outside of the apparatus by a mold conveyance system (not shown). The wafer 20 coated with the resist 21 is also transported and held by a wafer transport system (not shown) from the outside of the apparatus to the wafer chuck 36 on the wafer stage 35.

  The mold chuck 33 is attached to the gantry 32 via a mold driving unit 34 that can be driven in the Z, ωx, and ωy directions. The wafer stage 35 can be driven in the X, Y, Z and rotation directions (ωx, ωy, ωz) of each axis, and can perform XY movement and posture correction of the wafer 20 held on the wafer chuck 36 immediately below the mold.

  The wafer height sensor 37 is a line sensor fixed on the pedestal 32, and detects the height of the wafer 20 at the opposite position (interval in the Z direction between the sensor 37 and the wafer surface). The mold height sensor 38 is fixed on the wafer stage 35, and the wafer stage 35 is driven in the X and Y directions so that the mold height sensor 38 is positioned under the mold 10 held by the mold chuck 33. The height of the mold 10 at the position (the distance between the sensor 38 and the mold 10 in the Z direction) is measured.

  Reference numeral 23 denotes a flat plate which is a feature of the present invention. The flat plate 23 is a ring-shaped plate member having a thickness equivalent to that of the wafer, and is arranged on the wafer check 36 in a concentric position from the center of the wafer chuck so that the outer periphery of the wafer is covered when the wafer is chucked. Become.

  FIG. 1 illustrates transfer by step-and-repeat. FIG. 1-1 is a sectional view showing the relationship between the wafer and the mold when the mold pattern is transferred to the center shot of the wafer. Since the entire mold surface faces the wafer, it is possible to press the mold in the direction of the white arrow after parallelizing the mold and the wafer surface by a command from the main control unit 40 based on information from the mold height sensor 38. Figure 1-2 shows the transfer to the wafer peripheral shot. Since there is a flat plate 23, it becomes the same height as the outer periphery of the wafer, and the entire surface of the mold can be pressurized. Therefore, even in the peripheral shot where the wafer and the mold are not opposed to each other, the same mold pressing as in the central shot is possible, and the accuracy of the transfer pattern can be maintained. Since the mold can be transferred with the same pressing pressure at any position on the wafer, not only the pattern uniformity accuracy within the shot, but also the pattern uniformity accuracy between shots, which is an important element required for lithography, can be achieved. I mean.

  The width of the flat plate 23 is related to the area size of one shot to be transferred at a time and the number of chips in one shot, but when assuming 2 x 2 4 chips, it is more than half of the diagonal line in one shot area A width is desirable.

  Further, it is sufficient that the width is equal to the diagonal line width of the region where the pattern exists on the mold.

  FIG. 3 shows a flat plate according to the second embodiment of the present invention and a structure associated therewith. The present embodiment is different from the first embodiment in that the flush plate 23 is arranged on the wafer chuck via the spring 24 and the damper 25.

  The resist has a different material (especially elastic force in this case) and applied thickness depending on the actual transfer process, and the thickness of the wafer itself is within an allowable range. Therefore, the fixed thickness and elastic force provided in the first embodiment may be difficult to cope with a process that requires higher pattern accuracy.

  The damper 25 can change the elastic force of the flat plate by adjusting the internal hydraulic pressure or air pressure. When the mold 10 is pressed around the wafer, the pressure value of the damper 25 is transmitted to the main control unit 40, and the damper elastic force is feedback-controlled so as to be the same as the reaction force from the wafer. Therefore, it is possible to always transfer even peripheral shot portions with different processes to the entire mold surface with a uniform pressing pressure. A plurality of the springs 24 and the dampers 25 are arranged around the flat plate 23 as shown in FIG. 3B, and can be uniformly transferred with the mold pressing pressure in the peripheral portion shot in any direction of the wafer.

  In the first and second embodiments, by extending the outer periphery of the wafer as described above, even when transferring to a peripheral shot in which chipping occurs, a state where the entire surface of the mold is substantially opposed is created, and a desired pressing pressure is made uniform. It was to control. In the present embodiment, a flat plate is not provided, and the pressing pressure is applied only in the mold region actually facing the wafer. FIG. 4 is a schematic diagram showing the arrangement of mold pressurization points and transfer shot positions in this example. The three points 13-1, 13-2, and 13-3 are the pressurizing points, and the pressing pressure to the three points can be controlled independently by a command from the main control unit 40. In the transfer to the wafer center shot (for example, ST-2), the same pressing pressure is instructed to the pressing points 13-1, 13-2, and 13-3, and the desired pressing pressure is uniformly applied to the entire mold surface. When transferring to ST-4, which is a peripheral shot, the desired pressures P1 and P2 are applied to the pressurization points 13-1 and 13-2, and the pressurization point 13-3 at a location not facing the wafer surface. Set the pressing pressure to zero, or specify a weak pressure P3 that does not tilt the mold, and press the pressing pressure so that the pressing center of gravity of the mold comes to the position indicated by × in the ST-4 area in Fig. 4-b. Control. By controlling the pressing pressure at three points so that the position of x is near the center of the transfer shot, uniform transfer can be performed on the entire surface of the shot. Fig. 4-c shows the relationship between the pressurization point and shot size ST-0 (the shot size varies depending on the chip to be manufactured and is not always fixed). By adjusting the pressure balance, it is possible to control the mold pressing center of gravity within a substantially triangular region shown in gray. Conversely, at the pressurization points 13-1, 13-2, and 13-3 shown in the relationship of Fig. 4-c, it is impossible to control the mold pressing center of gravity to be in the area indicated by the white background of ST-0. Is possible. In order to make it possible to adjust the mold pressing center of gravity to all positions within the ST-0 area, for example, as shown in Figs. 43-1-1, 13-2, 13-3d, The pressurizing points 13′-1, 13′-2, 13′-3 may be arranged at the apexes. The pressurization control to each pressurization point is calculated and instructed by the main control unit 40 based on the shot layout information based on the opposing position of the mold and the wafer in the target shot.

  Since a flat plate is not required, the wafer chuck and the wafer stage on which the chuck is mounted can be reduced in size, which is also effective in terms of apparatus cost.

  Further, the number of pressurizing points is not limited to three, and four pressurizing points are possible as shown in FIG. In the case of four points, there is also an advantage that by placing pressure points at the four corners of a shot, it is possible to efficiently set the pressure center of gravity at a desired location.

  FIG. 6 shows a schematic configuration of a nanoimprint apparatus according to the fourth embodiment. Parts that are the same as the configuration / function shown in FIG. 2 in the first embodiment are denoted by the same reference numerals in the drawing, and thus description thereof is omitted. Similar to the third embodiment, by adjusting the position of the center of gravity of the mold pressing, the uniformity of the pressing pressure on the peripheral shot is obtained. In the third embodiment, instead of having a plurality of pressure points and controlling the pressing force of the plurality of pressure points independently and controlling the center of gravity, in this embodiment, the mold pressure is applied to the mold driver 34 '. It has a mechanism for moving the center of gravity in the xy plane. FIG. 7 is a schematic diagram showing the transfer shot position and the mold pressing center of gravity in this embodiment. Transfer to the center shot ST-2 is performed in a mold state indicated by a broken line in the figure so that the center of gravity of the mold press comes to the center of the mold. If the mold drive unit 34 'is initialized so that the mold pressurization center of gravity is at the center of the mold in the initialization process that is performed at the beginning of the device drive, the target shot can be made without giving the command value of the mold pressurization center of gravity. On the other hand, transfer can be performed with uniform pressing pressure. In the transfer to ST-4, which is a peripheral shot, the mold driving unit 34 "is controlled so that the center of pressure is aligned with the center of the area where the mold and the wafer indicated by x in the figure are facing each other. The main controller 40 calculates and instructs movement control to the mold driver 34 'based on the shot layout information based on the opposing position of the mold and the wafer in the target shot.

[Example of device production method]
Next, an embodiment of a device production method using the fine pattern forming apparatus or the fine pattern forming method described above will be described.

  FIG. 14 shows a flow of manufacturing a microdevice (a semiconductor chip such as an IC or LSI, a liquid crystal panel, a CCD, a thin film magnetic head, a macro machine, etc.). In step S1401 (circuit design), a device pattern is designed. In step S1402 (mold production), a mold on which the designed pattern is formed is produced. On the other hand, in step S1403 (wafer manufacture), a wafer is manufactured using a material such as silicon or glass. Step S1404 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by the imprint technique using the prepared mold and wafer. The next step S1405 (assembly) is called a post-process, and is a process for forming a semiconductor chip using the wafer produced in step S1404. The assembly process (dicing, bonding), packaging process (chip encapsulation), etc. including. In step S1406 (inspection), the semiconductor device manufactured in step S1405 undergoes inspections such as an operation confirmation test and a durability test. Through these steps, the semiconductor device is completed and shipped (step S1407).

  FIG. 15 shows a detailed flow of the wafer process. In step S1501 (oxidation), the wafer surface is oxidized. In step S1502 (CVD), an insulating film is formed on the wafer surface. In step S1503 (electrode formation), an electrode is formed on the wafer by vapor deposition. In step S1504 (ion implantation), ions are implanted into the wafer. In step S1505 (resist processing), a resist is applied to the wafer. In step S1506 (pattern transfer), the circuit pattern of the mold is transferred as an indentation to the wafer by the fine pattern forming apparatus described above. In step S1507 (etching), the remaining film portion of the transferred resist image is removed to form a pattern. In step S1508 (resist stripping), unnecessary resist after etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer. During the repetition, it is necessary to transfer the pattern onto the wafer using an exposure device instead of a fine pattern formation device, a mask (reticle) instead of a mold, and a photoresist because the resolution requirement is not strict. Combinations are also possible.

  By using the production method of this embodiment, a highly integrated device that has been difficult to manufacture can be manufactured at low cost.

The figure explaining the mold pressing concerning Example 1 of this invention. 1 is a schematic configuration diagram illustrating an imprint apparatus according to Embodiment 1 of the present invention. The figure explaining mold pressing concerning Example 2 of the present invention. The figure explaining mold pressing concerning Example 3 of the present invention. The figure explaining mold pressing concerning another form of Example 3 of the present invention. FIG. 6 is a schematic configuration diagram illustrating an imprint apparatus according to Embodiment 4 of the present invention. The figure explaining the mold pressing concerning Example 4 of this invention. The figure which shows the general shot layout in a mass production process. The figure explaining basic mold pressing. The figure explaining the mold pressing which becomes a problem. Conventional example (1) dealing with pressing uniformity. Conventional example (2) dealing with pressing uniformity. The figure explaining the mold pressing which also becomes a problem also in a prior art example. The figure explaining the flow of manufacture of a micro semiconductor device. The figure explaining the detailed flow of the wafer process in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Mold 11 Mold pattern 13 Pressing point 20 Wafer 21 Resist 22 Resist residual film part 23 Flat one plate 24 Spring 25 Damper 30 Imprint apparatus main body 31 Chamber 32 Mounting frame 33 Mold chuck 34 Mold drive part 34 'Pressure center of gravity movement possible Mold drive unit 35 Wafer stage 36 Wafer chuck 37 Wafer height sensor 38 Mold height sensor 39 Pressure sensor 40 Main control unit 41 W stage position control unit 42 M chuck position control unit 43 W height measurement unit 44 M height measurement unit
ST-0 to ST-4 Pattern transfer shot

Claims (9)

  A master holding mechanism for holding a master having a fine concavo-convex pattern on its surface, a substrate stage for holding and moving a substrate to which a pattern of the master is transferred, a master substrate and the substrate to be processed facing each other, In a fine pattern forming apparatus having a pressurizing mechanism for relatively pressing, and operating the pressurizing mechanism to perform pattern transfer on the surface of the substrate to be processed, the area of the area where the master and the substrate to be processed are facing each other A fine pattern forming apparatus comprising pressing control means for controlling pressing so that the center of gravity of pressure comes to the center.   The substrate stage to be processed has a ring-shaped structure that is substantially the same height as the surface of the substrate to be processed when held and is arranged substantially concentrically with the held substrate to be processed. The fine pattern forming apparatus according to claim 1.   3. The fine pattern forming apparatus according to claim 2, wherein a width of the ring-shaped structure is equal to or less than a width of a diagonal line of a region where the pattern of the master is present.   4. The fine pattern forming apparatus according to claim 2, wherein the ring-shaped structure is disposed on the workpiece substrate stage via a spring and a shock absorber.   2. The fine pattern forming apparatus according to claim 1, wherein the pressing mechanism has a pressing point at each vertex of at least three or more polygons that substantially include a region where the pattern of the master is present.   6. The fine pattern formation according to claim 5, further comprising a pressurization point control mechanism for controlling a pressure applied to each pressurization point so that the pressurization center of gravity comes to the inside of a region facing when transferring. apparatus.   2. The fine pattern forming apparatus according to claim 1, wherein the pressurizing mechanism has a pressurizing mechanism moving means capable of moving in a direction in the facing surface.   8. The fine pattern forming apparatus according to claim 7, wherein the pressurizing mechanism moving unit is driven so that the pressurizing center of gravity of the pressurizing mechanism is located in a region facing when transferring.   A semiconductor device manufactured using the fine pattern forming apparatus according to claim 1.

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