KR100760340B1 - A method and apparatus for controlling a balance of a substrate by torque control - Google Patents

Abstract

A method and an apparatus for controlling balance of a substrate using torque control is provided to decrease an aligning error of a stamp and a substrate by controlling torque of a motor. A stamp(2) with a pattern to be transferred is fixed by an upper support(1) using vacuum pressure. A substrate support(4) is installed at a position opposite to the upper support to fix a substrate(3) with vacuum pressure. The substrate support is supported by a lower support(7), and a tilting member(5) is interposed between the substrate support and the lower support to tilt the substrate support forwardly on the lower support. The lower support is moved by a motor(8). A vacuum port(6) is formed on the lower support, and the tilting member is positioned on the tilting member.

Description

Substrate balance control method and apparatus using torque control {A METHOD AND APPARATUS FOR CONTROLLING A BALANCE OF A SUBSTRATE BY TORQUE CONTROL}

1 is a schematic diagram of a conventional nanoimprint lithography process.

2 is a schematic cross-sectional view of a substrate balance control apparatus using torque control according to an embodiment of the present invention.

3 to 4 are schematic cross-sectional views showing the operation process of the substrate balance control device using the torque control shown in FIG.

5 is a motor torque change diagram of the substrate balance control device using torque control according to an embodiment of the present invention.

<Explanation of symbols for main parts of drawing>

1: upper support 2: stamp

3: substrate 4: substrate support

5: tilting means 6: vacuum port

7: lower supporter 8: motor

The present invention relates to a method and apparatus for controlling the balance of a substrate using torque control, and more particularly, to reduce the alignment error between the stamp and the substrate by controlling the torque of a motor for moving the support on which the stamp or substrate is mounted. The apparatus and method of the present invention can be most effectively applied to Precision Wafer alignment System Y used in lithography processes such as nanoimprint lithography processes.

Lithography is a technology for printing and forming complex patterns that define integrated circuits on semiconductor wafers. Advances in lithography technology have enabled the high integration of today's integrated circuits.

Background Art [0002] Optical lithography, which is widely used in the past, images a pattern on a reduced mask by using a high precision optical system on a semiconductor wafer coated with a photosensitive film. This optical lithography uses Krypton Fluoride (KrF) excimer lasers, currently producing 248 nm Deep Ultraviolet (DUV) via g-line (435 nm) and i-line (365 nm) as light sources, increasing resolution By incorporating various peripheral technologies, it is possible to mass-produce a transistor having a gate line width smaller than 125 nm.

But according to Moore's law, the productivity of ICs develops faster than optical lithography, so even if you use light sources with shorter wavelengths than KrF, such as ArF (Argon Fluoride) 193 nm lasers or Fluorine (F2) 157 nm lasers, Using conventional optical lithography, ultra-fine pattern formation below 70 nm is limited.

In other words, optical lithography makes it impossible to form a line width of less than 0.1 um, which will be required soon due to the rapid development of integrated circuits (actually, to make 256Mb DRAM, it is necessary to make a pattern of at least 0.25 micron, To make a 16x improvement in 4Gb DRAM, we need to create a pattern of at least 0.13 microns).

To overcome this limitation of optical lithography, so-called Next-Generation Lithographies (NGLs) are being developed, and EUV lithography (EUVL), X-ray lithography, Ion-beam Projection lithography, Electron-Beam lithography. , Dip pen lithography, AFM (Atomic Force Microscope) and Proximal Probe Lithography using Scanning Tunneling Microscope (STM) have been proposed, including extreme ultraviolet (EUV) having a wavelength in the range of 10-14 nm. EUVL is known as the leading NGL technology.

Such EUV lithography (EUVL) has many similarities to optical lithography, but since EUV is strongly absorbed in almost all materials, the use of EUV should be done in vacuum and using reflective optical systems rather than conventional refractive optics. However, due to the very low reflectance of EUV at orthogonal angles of incidence, the reflective surface must be multi-layer coated with a thin film known as Distributed Bragg Reflect, and a complete mirror is required, requiring very advanced polishing and metrology techniques.

In addition, since EUV absorption in general photo-resist is very high, new resists and process technologies have to be applied, and many studies have yet to be made before this technology can be commercialized by many technical difficulties and complicated manufacturing processes.

In the case of X-ray lithography, it is possible to form an ultra-fine pattern of 25 nm, but the production cost of the high power source (such as synchrotron source) is not only expensive, but also the manufacturing of optical system and mask is technically required. It is difficult and expensive, so commercialization is unlikely.

Ion-beam lithography is a method of focusing ion beams to reduce the projection of the mask pattern onto the resist, and it is difficult to technically overcome the problem of deformation of the ion beam cross-section due to chromatic aberration and space charge. There are many problems for the technology to be applied to the fabrication of nanodevices.

Electron-Beam (e-beam) lithography can form ultra-fine patterns at a relatively lower cost than X-ray lithography, but has a low throughput per hour, so it is essentially used for mass production in production. There is a limit.

Dip pen lithography and Proximal Probe lithography using AFM and STM, although capable of patterning in the order of nanometers or atoms and molecules, are still difficult to use on production sites due to their low productivity and technical maturity.

As described above, the lithographic method has a problem in that the maximum patterning area is small, the patterning speed and throughput are too low, and the cost is excessively consumed, resulting in economic mass production of nanopatterns. In addition, the application in the actual nanopattern process is extremely unrealistic because it requires a multi-step pretreatment process, requires a complicated device, or the pattern is too small to be used as a mask.

In contrast to these lithographic methods, the nanoimprint lithography method proposed by Professor Stephen Chou of Princeton University is in the spotlight as a technology for economic mass production of nanostructures and nanodevices. The proposed nanoimprint lithography method is a surface of a polymer resist coated on a substrate by compressing a substrate surface coated with a thermoplastic polymer such as polymethylmethacrylate (PMMA) with a stamp having a nano-sized structure (100 nm or less). This is how you move the pattern on the stamp. At this time, the nanostructures stamped on the resist is formed in the same shape as the stamp, the stamp is mainly made of silicon, silicon oxide, etc. having a nano-size pattern.

Such a nanoimprint lithography process will be briefly described with reference to FIG. 1 as follows.

A thermoplastic polymer such as PMMA is coated on the substrate 10 formed of a silicon wafer to form a resist layer 20, and a stamp 30 having a pre-fabricated nanopattern is pressed toward the resist layer 20 to obtain a stamp ( The nano pattern of 30 is transferred or imprinted into the resist 20. During the imprinting, a stamp (using a method of solidifying the resist by projecting ultraviolet rays onto the resist 20 (ultraviolet nanoimprint lithography) or a method of heating the resist 20 above the glass transition temperature (nanoimprint lithography) The pattern of 30) is well imprinted into the resist 20, and then the stamp 30 is separated from the resist 20, and if there is any remaining resist, it is removed by an isotropic etching method such as reactive ion etching (RIE). Form a polymer mask.

In such a nanoimprint lithography process, alignment of the substrate 10 and the stamp 30, that is, maintaining balance, should be performed very precisely. If such alignment or balance is not precise, the substrate 10 may be separated from the stamp 30. The transfer of the pattern to) may be incomplete.

In order to maintain the balance, conventionally, the movable supports on which the substrate 10 and the stamp 30 are mounted are moved by a servo control mechanism in a position control method. In this method, since the thickness of the stamp 30 and the substrate 10 must be input to the control program every time the new stamp 30 and the substrate 10 are mounted on the movable support, the substrate 10 is accurately It is difficult to form a soft contact of the stamp 30 and the stamp 30 has a wide range of alignment error between the stamp 30 and the substrate 10, thereby resulting in not only the deformation of the pattern during the transfer of the pattern but also cumbersome in the whole process The disadvantage is that the variable input step is repeated repeatedly.

The present invention has been made to solve the above problems, an object of the present invention is to control the torque of the motor for moving the support on which the stamp or substrate is mounted to reduce the alignment error between the stamp and the substrate and to provide a more accurate soft contact This is to prevent deformation of the pattern and to eliminate the unnecessary variable input step, thereby improving process efficiency.

The present invention for achieving the above object, the substrate balance control device using torque control, the upper support (1) for fixing the stamp (2) in a vacuum pressure; A substrate support (4) installed at a position facing the upper support (1) to fix the substrate (3) with vacuum pressure; A lower support 7 for supporting the substrate support 4; Tilting means (5) for connecting the central area of the substrate support (4) to be freely tilted forwardly on the lower support (7); A motor 8 for moving the lower support 7; And a controller (not shown) for controlling the motor 8.

Another invention for achieving the above object, the upper support (1) for fixing the stamp (2) in a vacuum pressure; A substrate support (4) installed at a position facing the upper support (1) to fix the substrate (3) with vacuum pressure; A lower support 7 for supporting the substrate support 4; Tilting means (5) for connecting the central area of the substrate support (4) to be freely tilted forwardly on the lower support (7); A motor 8 for moving the lower support 7; And a control unit (not shown) for controlling the motor 8. The method of controlling the substrate balance by controlling the torque of the motor, wherein the stamp 2 is fixed to the upper support 1 by vacuum pressure. Fixing the substrate 3 to the substrate support 4 facing the upper support 1 by vacuum pressure; Controlling the motor 8 to move the tilting means 5, the substrate support 4, and the substrate 3 provided on the lower support 7 and the lower support 7 to the upper support 1 side; ; And finely driving the motor 8 in a state where the substrate 3 and the stamp 2 are in soft contact so that the tilting means 5 equilibrates between the substrate 3 and the stamp 2. Characterized in that it comprises a.

Hereinafter, the present invention will be described in detail through an embodiment of the present invention shown in the accompanying drawings.

FIG. 2 is a schematic cross-sectional view of a substrate balance control device using torque control according to an embodiment of the present invention, and FIGS. 3 to 4 illustrate a process of operating the substrate balance control device using the torque control shown in FIG. 2. It is a schematic sectional drawing which shows.

In Fig. 2, the substrate balance control apparatus using torque control of the present embodiment is a device for finely aligning the stamp 2 and the substrate 3 in the nanoimprint lithography process. The apparatus comprises an upper support 1 for fixing the stamp 2 with vacuum pressure; A substrate support (4) installed at a position facing the upper support (1) to fix the substrate (3) with vacuum pressure; A lower support 7 for supporting the substrate support 4; Tilting means (5) for connecting the central area of the substrate support (4) to be freely tilted forwardly on the lower support (7); A motor 8 for moving the lower support 7; And a controller (not shown) for controlling the motor 8.

The tilting means 5 is placed on the vacuum port 6 formed above the lower support 7, and the vacuum port 6 and the tilting means 5 are applied to the lower support 7 via the principle of hydrostatic pressure. Force is uniformly transmitted to the substrate support 4. Accordingly, since the substrate support 4 is freely tilted on the lower support 7 without being restricted in direction and angle, the substrate support 4 is in equilibrium when the substrate 2 on the substrate support 4 comes into contact with the stamp 2. The position of the substrate support 4 is corrected to maintain the state. Subsequently, when the vacuum port 5 fixes the tilting means 5 with vacuum pressure, the equilibrium state is maintained even after the substrate support 4 is moved.

Hereinafter, the process of transferring the pattern of a stamp to a board | substrate using the board | substrate balance control apparatus using the torque control of a present Example is demonstrated.

As shown in FIG. 2, when the stamp 2 is positioned on the lower surface of the upper support 1, the controller (not shown) operates the upper support 1 to fix the stamp 2. The control unit generally controls the operation of the substrate balance control device using torque control, and is composed of a dedicated or general-purpose memory, a microprocessor and related servo mechanisms. The upper support 1 may be provided with a port (not shown) composed of a plurality of gas holes, and the stamp 2 may be fixed to the upper support 1 by adjusting the gas pressure (eg, suction) by the control unit. .

Subsequently, when the board | substrate 3 is mounted on the upper surface of the board | substrate support 4, the control part moves the board | substrate support 4, and fixes the board | substrate 3 to it. On the substrate 3, a thermoplastic polymer such as PMMA may be coated in advance to form a resist layer. In the case of the substrate support 4, a port (not shown) including a plurality of gas holes may be provided, and the substrate 3 may be fixed to the substrate support 4 by adjusting the gas pressure (eg, suction) by the controller. Can be.

In a state where the stamp 2 and the substrate 3 are fixed, the control unit operates the motor 8 to move the lower support 7 to the upper support 1 side as shown in FIG. 3. As the lower support 7 moves, the tilting means 5, the substrate support 4, and the substrate 3 provided on the lower support 7 move together, wherein the substrate 3 and the stamp 5 are moved together. Since the initial equilibrium is not completely achieved, the substrate 3 moves inclined as shown in FIG. 3.

Subsequently, when the motor 8 is driven slightly further in a state in which at least a part of the substrate 3 is in contact with at least a part of the stamp 2, that is, in a soft contact state, the substrate support is supported by the tilting means 5. 4 is freely tilted forwardly on the lower support 7 by the principle of hydrostatic pressure, as shown in FIG. 4, between the substrate 3 and the stamp 2 and between the upper support 1 and the substrate support 4. The substrate 3 and the stamp 2 are in perfect contact, i.e., hard contact and aligned.

Fig. 5 shows the motor torque change at each step of the substrate balance control method in the above embodiment.

In FIG. 5, step A is the no-load state of the motor 8, which shows the torque of the motor 8 before moving the lower support 7 as shown in FIG. 2.

Step B shows the torque of the motor 8 until just before the motor 8 moves the lower support 7 to the soft contact state of FIG. 3, and the torque of the motor 8 increases compared to the step A. You can see that.

Step C shows the torque of the motor 8 from the soft contact of FIG. 3 to the hard contact of FIG. 4, and it can be seen that the torque of the motor 8 increased significantly compared to the B step. .

In the present invention, the value of the torque load due to its own weight is set through a test. For example, the no-load torque of the motor 8 is T0 and the maximum torque load amount is Tmax, and the torque load amount in the stage B before the soft contact is formed is T1 and the torque until the hard contact is made after the soft contact. When the load amount is T2, T0 and Tmax are given by the specifications of the motor, but T1 and T2 are determined differently depending on the substrate material, size, and the like.

Through a plurality of tests, it is possible to determine T1 and T2 values suitable for a given substrate. In this case, in order to prevent malfunction of the substrate balance control apparatus of the present invention, the ranges of T1 and T2 values do not overlap and there must be considerable difference. That is, T0 <T1 <T2 <Tmax. For example, the load range T1 in the B stage before the soft contact is formed is set to about 200 to 700 [N · m], and the load amount T2 for signaling the motor to stop when the hard contact is made in the C stage is set to 1500 [. N · m], it is preferable to make the difference in the range of the load amount significantly in each step so that an error does not occur at the time of control.

As described in the above embodiments, the method and apparatus for controlling the substrate balance using the torque control of the present invention effectively control the torque of the motor for moving the support on which the stamp or substrate is mounted, thereby effectively reducing the alignment error between the stamp and the substrate. Can be reduced and more accurate soft contacts can be formed, thereby avoiding deformation of the pattern.

In addition, the substrate balance control method and apparatus using the torque control of the present invention, because it controls the torque of the motor for moving the stamp or the support on which the substrate is mounted, the unnecessary variable input step according to the thickness change of the substrate and the stamp Elimination can increase overall process efficiency.

In addition, according to the method and apparatus for controlling the substrate balance using the torque control of the present invention, when the contact between the stamp and the substrate, the alignment error is reduced and the equilibrium is maintained, so that the stamp and the substrate must be spaced according to a subsequent process. The stamp and substrate may be spaced apart while maintaining equilibrium.

Substrate balance control apparatus and method using the torque control of the present invention is a specific value by setting the contact position to 0 after the contact is made to maintain the balance of any two substrates in a process such as nanoimprint lithography, photolithography, etc. As long as it is necessary to give a gap between the substrate can be used in various ways,

While the invention has been shown and described with reference to specific embodiments, those skilled in the art will be able to make various modifications and improvements to the invention without departing from the scope of the invention as claimed in the claims.

Claims (6)

delete A stamp in which a pattern to be transferred is formed; An upper support for fixing the stamp with a vacuum pressure; A substrate support installed at a position facing the upper support to fix the substrate by vacuum pressure; A lower support for supporting the substrate support; Tilting means provided between the substrate support and the lower support to connect the substrate support freely tiltable on the lower support in all directions; A motor for moving the lower support; And A control unit for controlling the motor, The control unit controls the torque of the motor in accordance with the load on the motor, The upper side of the lower support is formed with a vacuum port, The tilting means lies on the vacuum port, And said vacuum port and said tilting means uniformly transmit a force applied to said lower support to said substrate support through the principle of hydrostatic pressure. The method of claim 2, The substrate balance control apparatus using the torque control is a substrate imbalance control apparatus using torque control, characterized in that the nanoimprint lithography equipment. The method of claim 2, The substrate balance control device using the torque control is applied to a precision wafer alignment system, the substrate balance control device using torque control. A stamp having a pattern to be transferred, an upper support for fixing the stamp with a vacuum pressure, a substrate support for fixing the substrate with a vacuum pressure at a position facing the upper support, a lower support for supporting the substrate support, A tilting means provided between the substrate support and the lower support so as to freely tilt the substrate support on the lower support in all directions, a motor for moving the lower support, and a control unit for controlling the motor. A method of controlling substrate balance using torque control in a substrate balance control apparatus comprising: Fixing the stamp to the upper support by vacuum pressure, and fixing the substrate to the substrate support by vacuum pressure; Driving the motor by the controller to move the tilting means, the substrate support, and the substrate provided on the lower support and the lower support to the upper support; And Finely driving the motor in a state where the substrate and the stamp make soft contacts, thereby causing the tilting means to equilibrate between the substrate and the stamp, And the control unit controls torque of the motor according to the load applied to the motor in each step. The method of claim 5, The motor torque control step of the control unit includes A, B, C steps, Step A is a no-load state before the motor is applied to the lower support, the torque of the motor is a torque T0 of no-load state, The step B is a state until the motor moves the lower support to contact the stamp and the substrate, the torque of the motor is increased to T1 compared to the step A, The step C is a state in which the stamp and the substrate gradually contact each other and completely contact each other, until the predetermined load is applied to the motor, and the torque of the motor increases to T2 compared to the step B, T0 << T1 << T2 The substrate balance control method using the torque control characterized by the above-mentioned.

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