JPH05296726A - Constant temperature device for measuring machine - Google Patents

Abstract

PURPOSE:To provide a constant temperature device for a measuring machine having the capability of restraining temperature dispersion in the travel zone of a sample table to carry a sample as a length measurement object. CONSTITUTION:A measuring machine body is supported on a surface plate 29 in a constant temperature bath. Also, a cover 30 is laid between a sample table 8 with a fixed mirror 24Y for reflecting a measurement laser beam, and a microscope 10. The size of the cover 30 is so selected as to conceal the whole travel zone of the table 8 in X-axis and Y-axis directions. Also, the support section 31 of the cover 30 has the view hole 30h of a microscope 10 formed through the cover 30 and a transmission hole 31h to allow the passage of a laser beam between an interferometer 23X and a mirror 24X. The predetermined temperature of the air above the constant temperature bath comes to the lower side of the cover 30, and temperature over the whole of the lower side of the cover 30 becomes approximately uniform.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermostat for a length measuring machine used for measuring a minute length with high accuracy.

[0002]

2. Description of the Related Art In recent years, in various technical fields, devices to be used have been miniaturized and have been made highly precise, and accordingly, strict control of the dimensions of each part of the device at the time of manufacturing has become necessary.
Therefore, there has been a demand for a length measuring machine capable of measuring with an accuracy of the order of sub μm. Here, a liquid crystal display device used for a display of a television, a computer, or the like will be described as an example of the object requiring the highly accurate length measurement as described above.

FIG. 3 is a layout view of electrodes of a liquid crystal display device. In the figure, reference numeral 1 is a substrate, and 2 is a large number of electrodes arranged vertically and horizontally on the substrate 1. For example, 6700 of these electrodes are arranged in a line in the horizontal direction on the substrate 1 having a length of 400 mm in the horizontal direction. Each of these electrodes 2 must be formed to have the same size, and they must be arranged at predetermined precise intervals with respect to each other. That is, as shown in FIG. 3, the dimensions Δx and Δy of each electrode 2 must be equal to each other within a predetermined allowable range, and the dimensions x ₁ and y ₁ between adjacent electrodes 2 must be accurate. I have to. Therefore, a master plate (mask) for manufacturing such an electrode pattern
The dimensions Δx, Δy, x ₁ and y ₁ in the above must be strictly controlled. For this purpose, a highly accurate length measuring machine is required. For example, in the above example, the dimension Δ
Since x is 30 μm and the dimension x ₁ is 60 μm, it is required that the length measuring machine be accurate to the order of sub μm. Such a length measuring machine is proposed by, for example, Japanese Patent Application No. 63-204786. This will be described with reference to FIG.

FIG. 4 is a perspective view of the length measuring machine. In the figure, 5
X and 5Y are XY stages supported on an air surface plate (not shown), and 6 is a movable table that can move left and right on the stage 5X. 7Y is a motor for displacing the stage 5X in the Y-axis direction, and 7X is a motor for displacing the moving table 6 in the X-axis direction. 8 is a sample table, and the fine movement mechanism 1 is attached to the moving table 6.
It is fixed through 8. The fine movement mechanism 18 includes the movable table 6
On the other hand, it is a device for displacing the sample table 8 by a small dimension in the X and Y axis directions. Reference numeral 9 indicates the original plate placed on the sample table 8, and 9p indicates an electrode pattern formed on the original plate 9. The electrodes of the electrode pattern 9p are arranged at the same size and at the same intervals as the electrodes 2 shown in FIG.

Reference numeral 10 is a microscope for enlarging and observing the electrode pattern 9p, 11 is a stand for supporting the microscope 10, and 12 is a stand.
Is a light source for illuminating the original plate 9, 13 is a light guide tube for guiding the light of the light source 12, and 14 is a CCD camera for taking an image of the microscope 10. Reference numeral 16 denotes an image processing device, which is composed of an image processing unit 16a and a display unit 16b, performs required processing on a microscope image taken by the CCD camera 14, and displays it. Reference numeral 17 is a control device for the length measuring machine, and 19 is a fine movement controller for driving the fine movement mechanism 18 under the control of the control device 17.

Reference numerals 20a, 20b and 20c designate a base, and 21 designates a base 2.
A laser head 22 is fixed on the laser beam 0a, and a beam splitter 22 separates the laser beam from the laser head 21 in the X-axis direction and the Y-axis direction. Reference numerals 23X and 23Y are interferometers fixed on the bases 20c and 20b, and 25X and 25Y are receivers fixed on the bases 20c and 20b, respectively. Reference numeral 24 is an L-shaped mirror fixed to the sample table 8 and is a mirror 2 extending in the X-axis direction.
The mirror 24Y extends in the 4X and Y-axis directions. Reference numeral 26 is a pulse comparator.

An outline of the operation of such a length measuring machine is shown in the microscope 1
This will be described with reference to FIGS. 5 and 6 showing the field of view of 0. When measuring the distance in the X-axis direction between one electrode 9p ₁ of the electrode pattern 9p and the electrode 9p ₂ adjacent thereto, first, the right edge portion of the electrode 9p ₁ of the microscope 10 as shown in FIG. Place in field of view A. In the figure, 9p ₀₁ is the electrode 9p ₁
And C shows the center line of the visual field A. The edge appears as unevenness. The unevenness is determined as one edge line E by the arithmetic processing of the image processing unit 16. The distance δ ₁ between the edge line E and the center line C at this time is calculated by the arithmetic processing of the image processing unit 16.

Then, the motor 7X is driven to move the sample table 8 in the X-axis direction so that the right edge portion of the electrode 9p ₂ is brought into the visual field A of the microscope 10 as shown in FIG.
In the figure, 9p ₀₂ is a microscope image of the electrode 9p ₂ . Similar to the case of the microscope image 9p ₀₁ , the edge line E is determined and the distance δ ₂ is calculated. The moving distance of the sample table 8 in the X-axis direction is L
Then, the distance between the right edge of the electrode 9p _{1 and} the right edge of the electrode 9p ₂ is (L + δ ₁ + δ ₂ ).

The moving distance L of the sample table 8 is obtained as follows. That is, the laser beam from the laser head 21 is applied to the mirror 24X via the beam splitter 22 and the interferometer 23X, and the input beam and the reflected light from the mirror 24X are interferometer 2.
Interference is performed at 3X, a signal corresponding to the degree of this interference is output from the receiver 25X, converted into a pulse proportional to the signal by the pulse comparator 26, and the moving distance L is calculated by the control device 17 based on this pulse. .. Also, the distance δ ₁ ,
δ ₂ can be made zero by using the fine movement mechanism 18 so that the edge line E and the center line C coincide with each other. At this time, the value obtained by the laser displacement meter is the distance.

By the way, since an ordinary object has a coefficient of thermal expansion, the ambient temperature has a great influence on the measurement in the sub-μm order. For example, when the original plate 9 is soda glass,
Since the thermal expansion coefficient of soda glass is (9.4 / 10 ⁶ ), if one side of the original plate 9 is 400 mm, ±
When changing by 0.1 degree (Celsius), one side of the original plate 9 is ± 0.3
Change by 7 μm. In order to eliminate the influence of the environmental temperature, the measurement using the length measuring machine is performed by placing the length measuring machine main body excluding the control part in a constant temperature bath. This constant temperature bath is, for example, (2
It has a size of m × 2 m × 2 m) and air at a predetermined temperature is constantly blown from above (ceiling) to keep the inside of the thermostatic chamber at a constant temperature.

[0011]

In the length measuring machine shown in FIG. 4, the size of the sample table 8 is, for example, (500 mm ×
500 mm) and the strokes of the XY stages 5X and 5Y are, for example, (400 mm × 400 mm),
The moving area of the sample table 8 is (900 mm x 900 m
m). Therefore, in order to perform high-accuracy measurement, the temperature in the moving area is set within a predetermined allowable range,
For example, it is necessary to maintain a predetermined constant temperature within ± 0.1 degrees (Celsius).

However, when the temperature in the vicinity of the sample table 8 was actually measured using a temperature sensor, it was found that there were variations in temperature even in the constant temperature bath. This will be described with reference to FIGS. 7 and 8. FIG. 7 is a layout view of the temperature sensor. In the figure, the same parts as those shown in FIG. 4 are designated by the same reference numerals. S _{1 to} S ₉ indicate temperature sensors arranged in a line at equal intervals. Figure 8 is a graph showing the measurement results of the temperature sensors S ₁ to S _9, the temperature sensors S ₁ to S ₉ to the horizontal axis, the temperature on the vertical axis are taken. As is clear from the measurement results shown in FIG.
The temperature in the vicinity of the temperature range including 2) varies in the range of 22.9 degrees to 23.2 degrees. Such temperature variation means that there is temperature variation in the moving area of the sample table 8, which impedes high-accuracy measurement.

An object of the present invention is to solve the above-mentioned problems in the prior art and to provide a thermostat for a length measuring machine which can suppress variations in temperature in the moving region of the sample table.

[0014]

Means for Solving the Problems The inventors have made various studies on the cause of variations in the temperature in the vicinity including the sample table. From the results of the above temperature measurement, the presence or absence of the sample table greatly affects the temperature variation. Found to be involved. Therefore, in order to suppress variations in temperature within the moving area of the sample table, the present invention enlarges the image of the moving stage, the sample table on which the measuring object is placed and moved by the moving stage, and the measuring object. A microscope, a camera for taking an enlarged image of this microscope, and a laser displacement meter for measuring the amount of movement of the sample table, in a length measuring machine supported via an air surface plate in a constant temperature bath,
A cover is provided between the microscope and the sample table to cover at least the entire moving range of the sample table while leaving the field of view of the microscope.

[0015]

The air of a predetermined temperature from the upper part of the constant temperature chamber penetrates into the cover and keeps the air inside the cover at a uniform temperature regardless of the presence of the sample table. Therefore, the measurement by the length measuring machine can be accurately performed.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to illustrated embodiments. 1 is a partial cross-sectional side view of a thermostat of a length measuring machine according to an embodiment of the present invention, and FIG. 2 is a plan view of the apparatus shown in FIG. In each figure, the same or equivalent parts as those shown in FIG. 4 are designated by the same reference numerals and the description thereof will be omitted. 28 is the floor of the thermostat, and 29 is the air surface plate that supports the length measuring machine body. Thirty
Is a cover and is interposed between the sample table 8 and the microscope 10. 30 h indicates a see-through hole of the microscope 10 formed in the cover 30. The size of the cover 30 is selected so as to cover the entire moving region of the sample table 8 in the X-axis direction and the Y-axis direction.

Reference numeral 31 denotes a supporting portion for supporting the cover 30,
Reference numeral h is a transmission hole formed in the support portion 31 for transmitting a laser beam between the interferometer 23X and the mirror 24X. Although not shown, a similar transmission hole is also formed between the interferometer 23Y and the mirror 24Y. The support portion 31 may be configured to cover the entire four side surfaces, or may be configured to leave a space on the side surfaces. As shown in the figure, when the motors 7X and 7Y are arranged outside the support portion 31, the support portion 31 is provided with a through hole through which each motor shaft is inserted.

The cover 30 has a portion 3 as shown in FIG.
It is divided into 0A, 30B and 30C, the portion 30A is fixed to the support portion 31, and at least one of the portions 30B and 30C is configured to be openable / closable or detachable for attachment / detachment of the original plate 9. Each part 30A, 30B, 30C
The size of can be arbitrarily selected in consideration of the size of the original plate 9 and the like. Further, the position of the see-through hole 30h is set to the respective portions 30
It is selected according to the size of A, 30B, 30C and the position of the microscope 10.

Now, regarding the conventional example in which the temperature sensors are arranged as shown in FIG. 7, the temperature sensors S _{2 to} S ₆ are
It is on the sample table, and S ₁ and S _{7 to} S ₉ are out of the sample table. On the table, the air flow is more likely to stagnant evenly than in a place without the table. Further, since the position of the temperature sensor for controlling the constant temperature bath is on the sample table, the temperature is controlled at this point. Therefore, the stagnation points S _{2 to} S ₆ of the air flow are likely to reach the established temperature of the constant temperature bath,
Since S ₁ and S _{7 to} S ₉ have no stagnation of the air flow, the more they are separated from the stagnation state of the air flow, the more easily they are overcooled.
However, in the present embodiment, the entire surface of the length measuring range is covered with the entire surface of the cover so that the air flow can easily stagnate and the surface temperature can be made uniform, so that the measurement by the length measuring machine can be performed accurately.

The see-through hole 30h is also in the same state as the cover 30 because the sample table is immediately below. The temperature sensor for control is provided on the upper surface of the cover 30, and the temperature sensor controls the temperature to a set temperature, so that the lower surface of the cover 30 is maintained at a substantially uniform temperature and variation in temperature is suppressed. Therefore, the original plate 9
The measurement against is not affected by temperature variations,
It can be performed with high precision.

[0021]

As described above, according to the present invention, since the cover for covering the entire moving area of the sample table is provided, it is possible to suppress the temperature variation in the moving area.
Highly accurate measurement can be performed.

[Brief description of drawings]

FIG. 1 is a side view of a thermostat of a length measuring machine according to an embodiment of the present invention.

2 is a plan view of the device shown in FIG. 1. FIG.

FIG. 3 is a plan view of an original plate to be measured.

FIG. 4 is a perspective view of a length measuring machine.

FIG. 5 is a diagram showing a field of view of a microscope.

FIG. 6 is a diagram showing a field of view of a microscope.

FIG. 7 is a layout view of temperature sensors on a sample table.

8 is a graph showing a measurement result obtained by the temperature sensor shown in FIG.

[Explanation of symbols]

 8 sample table 10 microscope 23X interferometer 29 air surface plate 30 cover 30h see-through hole 31 support part

Claims (1)

[Claims] 1. A moving stage, a sample table on which a length measuring object is placed and moved by the moving stage, a microscope for magnifying an image of the length measuring object, a camera for taking a magnified image of the microscope, and In a length measuring machine that is composed of a laser displacement meter that measures the amount of movement of the sample table and is supported in the thermostatic chamber via an air surface plate, at least the entire moving range of the sample table is covered while leaving the field of view of the microscope. A thermostat of a length measuring machine, wherein a cover is interposed between the microscope and the sample table.