JP2011007708A - Viscosity characteristic measuring device of thin-film-like liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure the viscosity characteristic of thin-film-like liquid having thickness of 1 μm or smaller.SOLUTION: This viscosity characteristic measuring device faces a flat surface of a fixed plate to a flat surface of a movable plate in parallel via a liquid film of a predetermined thickness, oscillates the movable plate in parallel with and linearly to the fixed plate while holding the liquid film, and measures the viscosity characteristic of the liquid film based on the oscillating speed and viscous force acting on the movable plate. In this device, a fixed plate fixture for holding the fixed plate in the oscillating direction of the movable plate has a bottom surface orthogonal to the oscillating direction of the movable plate, and the bottom surface can move on with the liquid film so as to hold the liquid film in the surface orthogonal to the oscillating direction of the movable plate.

Description

  The present invention relates to an apparatus for measuring viscosity characteristics of a thin film-like liquid.

  There are various methods for measuring the viscosity, but as a method for measuring the viscosity of a liquid that is relatively close to a thin film state, a flat pressing surface is applied to a thin film-like sample formed on a substrate as seen in Patent Document 1. 2. Description of the Related Art Viscosity measuring apparatuses are known that measure the viscosity of a sample by pressing and rotating a rotor having a constant pressure and detecting the magnitude of a reaction force against the rotational force.

Further, as shown in FIG. 1, a disk-shaped parallel plate is opposed to each other, a liquid film of a liquid whose viscosity is to be measured is held between them, and the other is rotated with respect to one fixed parallel plate. An apparatus for measuring viscosities is also known.
In this type of rotational viscosity measuring device, first, the parallel plates are brought into contact with each other in the absence of a liquid, and the origin position where both are in contact is obtained.
Next, prepare a liquid on one side of the parallel plate, press the other parallel plate against the liquid, bring it close to the parallel plate while discharging the liquid until the gap between the parallel plates reaches a specified distance, and at a specified distance. Hold the parallel plate position.

By rotating the parallel plate pressed against the liquid in this state, the relationship between the rotational speed and the torque can be obtained, and the viscosity can be determined from the parallel plate gap.
In the conversion to viscosity, the error factors are the surface accuracy of the flat surface of the parallel plate, the perpendicularity between the rotation axis and the plane, and the parallelism between the rotation surface and the fixed surface with respect to the gap between the parallel plates. In any case, the wider the gap, the better. If the torque can be detected sufficiently, it is possible to measure accurately by widening the distance of the gap, and actually the measurement is performed at a gap of at least 10 μm. . Conversely, in the case of a liquid film of 10 μm or less, measurement cannot be performed unless the above error factors are eliminated.

JP 61-132840 A

In general, in such viscosity measurement, since there is substantially no correlation between the thickness of the liquid film and the measured viscosity value, if the liquid film is held between parallel plates at 10 μm or more and can be measured There is no accuracy problem with the measured viscosity.
By the way, in the case of a liquid photocurable resin used for ultra-high-definition pattern formation called optical nanoimprint, the liquid film of the photocurable resin is uniformly applied to about 1 μm or less. Since the throughput of photo nanoimprint is greatly influenced by the viscosity of the photocurable resin in this state, it is required to accurately measure the viscosity of such an extremely thin liquid film.

  In such an extremely thin liquid film, the surface area becomes very large compared to the volume. For example, in the case of a photo-curing resin, the volatile component contained volatilizes from the liquid film surface, resulting in a large viscosity coefficient. Change. Therefore, even if the viscosity of the photo-curing resin can be measured with a liquid film of 10 μm or more with a conventional viscosity measuring device, there is a high possibility that it is different from the actual viscosity in an extremely thin film state, and there is no means for obtaining a correct viscosity value. It was.

  Accordingly, an object of the present invention is to provide an apparatus for measuring viscosity characteristics of a thin film-like liquid that can accurately measure the viscosity of a thin film of about 1 μm or less.

  In order to solve the above problems, the viscosity characteristic measuring apparatus of the present invention is configured such that the flat surface of the fixed plate and the flat surface of the movable plate face each other in parallel through a liquid film having a predetermined thickness, and the movable plate is In the apparatus for measuring the viscosity characteristics of the liquid film based on the vibration speed and the viscous force acting on the movable plate while vibrating the liquid film in parallel and linearly with respect to the fixed plate. A fixed plate jig for holding the fixed plate in the vibration direction of the movable plate has a bottom portion perpendicular to the vibration direction of the movable plate, and the bottom portion is in a plane perpendicular to the vibration direction of the movable plate. It was made possible to follow and move to hold the membrane.

  According to the present invention, even if there is an error in the surface accuracy of the flat surface of the fixed plate and the flat surface of the movable plate, or there is a mechanism error such as play in the drive mechanism of the movable plate, Since the bottom surface of the fixed plate jig that holds the fixed plate follows and moves in a plane orthogonal to the vibration direction of the movable plate, even if the liquid film is 1 μm or less, the liquid The film is securely held between the flat surface of the fixed plate and the flat surface of the movable plate, and the viscosity of the liquid in the state of the liquid film thickness can be accurately measured.

It is a figure which shows the schematic of the conventional parallel plate type viscosity measuring apparatus. It is a schematic diagram which shows the definition of a viscosity. It is a figure which shows the state of the thin film formation by application | coating. It is a figure which shows the state of the thin film formation by dripping. It is a figure which shows the example of the viscosity characteristic measuring apparatus by this invention, (a) is a front view, (b) is a side view. It is a figure which shows the whole structure of a viscosity characteristic measuring apparatus.

  Fig. 2 shows the principle of viscosity measurement. Viscous resistance is proportional to viscosity, plate area, plate speed, and inversely proportional to the gap, so the plate speed at a certain time and the plate at that time are driven. If the force required to do this can be known, the viscosity can be determined from the area and gap of the plate.

  In the present invention, basically, as shown in FIG. 3, the other plate is brought into contact with the plate on which the liquid film is uniformly applied, and the film thickness of the originally applied liquid is measured as it is. Do. In general, when the film thickness of the liquid is reduced, it becomes difficult for the liquid to be discharged out of the gap between the plates even when the plates are pressed against each other. In particular, if the force pressing the plates is sufficiently small, the liquid is hardly discharged out of the gap between the plates, and the film thickness of the original liquid is maintained.

  Instead of applying the liquid film as shown in FIG. 3, the liquid is dropped on the plate as shown in FIG. 4, the other plate is brought into contact, the liquid spreads between the plates, and is held between the plates. As a result, it is possible to form a uniform liquid film as a result.

  In any case, since the film thickness of the liquid is automatically determined by the applied film thickness or the volume of the supplied liquid, the control of the gap is less than when the gap between the plates is controlled by an external force. It becomes easy. In particular, when the liquid film becomes thin, the gap interval can be determined with high accuracy.

  In order to realize such contact, in addition to the flat surface of the plate, it is necessary that the surface of the plate has a so-called liquid wetting property. In addition, the characteristic that the surface of the plate is wetted with the liquid is that the contact angle when the liquid is dropped on the surface of the plate is 90 degrees or less, and the liquid film is stable under this condition. Can be held in. Once the liquid is in contact with the two plates and the liquid is in a wet state, a force is required to separate the two plates, and the force to separate the plates after contact is less than a predetermined value. If present, the contact state is maintained against this, and the liquid film is maintained.

  Here, considering the case where one plate is vibrated linearly with respect to the other plate for viscosity measurement in a state where the liquid is held in a wet state between the two plates, the sliding shaft This is not a problem if the sliding surfaces are completely parallel to each other. However, in practice, it cannot be made completely parallel due to the limits of the surface accuracy of both plates and the mechanical accuracy to generate vibration. When sliding, a force or torque is generated to separate the plates.

  Here, it is assumed that the liquid is already held between the two plates. However, when the plates are brought into contact with each other through the liquid, the sliding surfaces of the two plates are separated by the thickness of the liquid. And they must be perfectly parallel. In order to realize this configuration, it is practically very difficult when a portion supporting two plates is fixed.

First, if the deviation in parallelism is large, the plates cannot be brought into contact with each other through the liquid. If the parallelism is slight, contact between the two plates via the liquid can be temporarily realized by utilizing deformation at the plate or the portion that supports the plate. There is a high possibility that the contact state will be broken by a strong vibration.
In order to measure viscosity, it is necessary to slide the plates relative to each other, and one plate must be connected to the drive unit, and the other must be connected to the fixed unit. Since there is always a deviation, a force or torque is generated to break the contact state when any of the plates is connected.

  5 (a) and 5 (b) are examples of an apparatus adopting the present invention having a mechanism for relaxing force or torque for breaking such a contact state by rotating or translating a plate. Here, a quartz plate having a flat surface having a size of 10 mm square and a surface accuracy of λ / 20 is used as the movable plate, and a silicon wafer having a flatness of about 0.2 μm in a 10 mm square range is used as the fixed plate. In this embodiment, the liquid to be measured is applied to a fixed plate made of a silicon wafer to form a liquid film of about 1 μm, and the viscosity of this liquid is measured. If the liquid film is thinner, a silicon wafer having better flatness or a quartz plate having a flat surface of λ / 20 is used as the fixed plate.

  FIG. 6 is a schematic diagram of the apparatus of FIG. The fixed plate 1 is substantially circular, and is fixed perpendicularly to the horizontal plane by a fixture 3 attached to the upper surface of the fixed plate jig 2, and the bottom surface of the fixed plate jig 2 is horizontal to the upper surface of the support base 4. It is mounted on.

  On the other hand, the movable plate 5 is held by the movable plate jig 6 so as to be rotatable around the horizontal axis 7. The movable plate jig 6 has a position acting on the movable plate 5 and a force acting on the movable plate 5. It is connected to a known actuator equipped with a sensor for measuring the pressure. At the time of measurement, the flat surface of the fixed plate 1 and the flat surface of the movable plate 5 face each other in parallel and are held wet by a liquid film of 1 μm or less. While maintaining parallel to each other, the position of the movable plate 5 and the force acting on the movable plate 5 are recorded at a predetermined time interval by being vibrated in the vertical direction with a predetermined amplitude and frequency.

  In this embodiment, a liquid such as a commercially available lubricating oil is applied between the bottom surface of the fixed plate jig 2 that holds the fixed plate 1 and the upper surface of the support base 4, so that the movable plate 5 is vibrated in the vertical direction. Following this, the fixed plate 1 is held so as not to vibrate in the vertical direction. Instead, the bottom surface of the fixing plate jig 2 that holds the fixing plate 1 and the upper surface of the support base 4 may be surface-treated with a resin having self-lubricating properties.

  With this installation method, the fixed plate jig 2 can be translated on the upper surface of the horizontal support base 4 in the radial direction, that is, in the front-rear and left-right directions, and in the rotational direction, that is, around the vertical axis centered on an arbitrary position. Therefore, the movement in the vertical direction is suppressed.

In measuring the viscosity of the liquid, the liquid plate is applied as described above, and then the movable plate 5 and the fixed plate 1 are brought into contact with each other. At this time, since the movable plate 5 can rotate around the horizontal axis and the fixed plate 1 can rotate on the upper surface of the horizontal support base 4 with limited degrees of freedom in the radial and rotational directions, the fixed plate jig 2 Can always be parallel regardless of the position on the support base 4.
Moreover, since the fixed plate jig 2 can move in the radial direction and in the circumferential direction on the support table 4 in this parallel state, it can be moved so as to contact the movable plate 5. That is, by adopting this structure, the movable plate 5 and the fixed plate 1 can always be contacted in parallel in principle.

  In actual contact work, there may be a case where the fixed plate jig 2 is not in an ideal position on the support base 4 and the movable plate 5 and the fixed plate 1 are not parallel, but the two are almost parallel. In this state, by applying an external force, the movable plate jig 6 and the fixed plate jig 2 are moved and adjusted in the biaxial direction, and the fixed plate 1 and the movable plate 5 hold, for example, a liquid film of 1 micron. Both can be positioned to be in a state.

  In this apparatus, since the fixed plate jig 2 is installed on the support base 4 in a lubricated state, if the movable plate and the fixed plate are in contact with each other by an external force, the fixed plate jig 2 is By moving and rotating on the upper surface of the support 4, the fixed plate 1 can maintain a liquid film of 1 μm or less with respect to the movable plate 5. At this time, the displacement of the movable plate jig 6 and the fixed plate jig 2 is alleviated with time.

  Moreover, even if the external force having the effect of bringing the movable plate 5 and the fixed plate 1 into contact with each other is removed, the movable plate 5 and the fixed plate can be removed even if the above-mentioned positional deviation is originally sufficiently small or sufficiently small after a sufficient time. 1 maintains the contact state between the movable plate and the fixed plate via the liquid by the action of trying to continue the wet state.

  Here, consider that the movable plate 5 is vibrated in the vertical direction with respect to the fixed plate 1. Although it is desirable that the vibration direction of the actuator and the contact surface of the movable plate 5 and the fixed plate 1 are parallel, since they are slightly shifted in practice, a force or torque for separating the plates is generated. However, even in this case, the fixed plate jig 2 moves and rotates on the upper surface of the support base 4, and the fixed plate 1 moves and rotates while maintaining contact with the movable plate 5 to separate the plates. The power to be relaxed.

  If the vibration direction of the actuator and the parallelism of the contact surface of the movable plate 5 and the fixed plate 1 are high and the viscous resistance when the fixed plate jig 2 moves on the upper surface of the support base 4 is sufficiently small, the movable plate 5 and the fixed plate 1 can be vibrated in the vertical direction while maintaining contact with the liquid.

  At this time, the movable plate 5 and the fixed plate 1 are in contact with each other by measuring the velocity from the velocity or position of the movable plate 5 and measuring the force in the vibration direction generated during the vibration. The viscosity of the liquid can be determined from the area and the film thickness of the liquid.

  In the case of the configuration of the present apparatus, the movable plate 5 and the fixed plate 1 are in a state where they can be moved in the horizontal direction at any time in the contact surface direction, but by adjusting the horizontal state of the support base 4, The movable plate 5 can be slid in the vertical direction with a sufficiently small horizontal movement.

  In the configuration of this apparatus, the movable plate jig 6 has a rotation function of one degree of freedom and the fixed plate jig 2 has a rotation function of one degree of freedom. It is also possible to collect them in any one of the plate jigs 2.

In the configuration of this apparatus, the fixed plate jig 2 is provided with a translation function having two degrees of freedom, but the movable plate jig 7 may be provided with an equivalent translation function.
In this embodiment, the fixed plate 1 is supported by the fixed plate jig 2 in the vertical direction and the movable plate 5 is vibrated in the vertical direction. However, the fixed plate 1 and the movable plate 5 can be opposed in parallel. If there is, it is not necessary to make the two exactly vertical, and there is no problem even if they are slightly inclined.
Further, if an attachment structure is employed in which the parallelism between the fixed plate 1 and the movable plate 5 is reliably maintained, the movable plate 5 does not need to be supported around the horizontal axis 7 so as to be rotatable.

  The viscosity characteristic measuring apparatus of the present invention can accurately measure the viscosity characteristic in a very thin liquid film state of about 1 μm or less, for example, for a liquid photocurable resin used for forming an ultra-high-definition pattern. The optical nanoimprint throughput can be accurately predicted.

DESCRIPTION OF SYMBOLS 1 Fixed plate 2 Fixed plate jig 3 Fixing tool 4 Support stand 5 Movable plate 6 Movable plate jig 7 Horizontal axis

Claims (3)

The flat surface of the fixed plate and the flat surface of the movable plate are faced in parallel through a liquid film having a predetermined thickness, and the movable plate is held parallel to and linear with respect to the fixed plate while holding the liquid film. In the apparatus for measuring the viscosity characteristics of the liquid film based on the vibration speed and the viscous force acting on the movable plate,
A fixed plate jig for holding the fixed plate in the vibration direction of the movable plate has a bottom surface orthogonal to the vibration direction of the movable plate, and the bottom surface is in a plane orthogonal to the vibration direction of the movable plate, Viscosity characteristic measuring device that can move following the liquid film.   The viscosity characteristic measuring apparatus according to claim 1, wherein the fixed plate jig is placed on an upper surface of a support base, and a liquid is applied to a bottom surface of the fixed plate jig and an upper surface of the support base.   The viscosity characteristic measuring apparatus according to claim 1, wherein the fixed plate jig is placed on an upper surface of a support base, and a self-lubricating resin is applied to a bottom surface of the fixed plate jig and an upper surface of the support base.