JPS63292002A - Length measuring apparatus by laser - Google Patents

Abstract

PURPOSE:To make it possible to convert a unit at high speed in a small scale, by adding a device which thins out length measurement pulses from a laser length measurer in accordance with a prescribed rule. CONSTITUTION:Length measurement pulses from a laser length measurer 201 are inputted to a counter 202 for a thin-out control, and outputs from the counter are compared 204 with output data from a thin-out number control circuit 203. In the case where 91st and 92nd pulses are thinned out, for instance, the circuit 203 outputs 91 and 92 to the comparator 204. Then a gate circuit 205 is closed for the thinned-out pulses and they are not inputted to a counter 206 for position measurement. Meanwhile, these pulses reset the counter 202. Therefore, an output thereof turns to be zero and thus it turns to be discord with the output from the circuit 203. As the result, the circuit 205 is opened and pulses other than the thinned-out are inputted to the counter 206. Thereby, the counter 206 can be regarded as a counter on 0.01mum basis, and an output thereof is sent directly to a charged-beam exposure device 207 without passing through a memory or the like.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a laser length measuring device that can perform length measurement unit conversion at high speed, and in particular, it performs lithography without continuously moving a sample to be exposed. How to draw a sample by continuously moving it.

(Prior Art) Charged beam exposure equipment often uses a laser length measuring device to measure the position of the exposed sample with high precision.
Its unit is usually an integer fraction of the laser wavelength, so
It does not match the LSI design unit. For example, Ha-Ne
In the case of a laser, the wavelength in vacuum is approximately 0.6330 μm, and if 1/64 of that is the length measurement unit, it is approximately 0.0098 μm.
It is 9μm, but the unit used for LSI design is 0.01
Since it is a numerical value that does not produce a fraction like μm, the two do not match. For this reason, it is necessary to convert the length measurement results by the laser into LSI design units. By the way, in a charged beam exposure system that uses a continuous sample movement drawing method, the beam irradiation position changes moment by moment as the sample to be exposed moves, so the position of the sample to be exposed is measured in real time and the measurement results are It is necessary to feed back the beam deflection data at high speed. That is, the above unit conversion needs to be performed as quickly as possible in a charged beam exposure apparatus using a continuous sample movement drawing method. In conventional devices, this unit conversion was accomplished using memory. That is, as shown in FIG. 2, conversion data corresponding to the length measurement data is stored in the memory 103 in advance, and the length measurement pulse from the laser length measurement device 101 is stored in the counter 102.
Then, count the data 10 in units of 0.00989 μm.
After obtaining 4, read the contents of the memory 103 using this as an address.
05 is obtained and sent to the charged beam exposure device 106. This method has the advantage of simple configuration.

(Problems to be Solved by the Invention) However, from the point of view of unit conversion speed, there is a problem in that a large number of high-speed memories with low packaging density must be used, and an increase in scale is unavoidable.

The purpose of the present invention is to solve the above-mentioned problems with conventional devices,
An object of the present invention is to provide a laser length measurement device that performs small-scale and high-speed unit conversion.

(Means and effects for solving the problems) In order to achieve the above object, the present invention adds a device to a conventional laser length measuring device to thin out the length measuring pulses from the laser length measuring device according to a certain rule. is the most important feature. Therefore, there is no need to use a large-scale, high-speed memory as in conventional devices, and unit conversion can be performed on a small scale and at high speed.

(Example) Examples of the present invention will be described in detail below.

As an example, an apparatus for converting length measurement results in units of 1/64 of the wavelength of a He-Ne laser into data in units of 0.01 μm will be shown. As mentioned above, the wavelength of He-Ne laser is 17
Since 64 is approximately 0.00989 μm, for example, if the sample moves IIIl, the measurement length/4' Lus is 101107
will be output. Therefore, if you can thin out 1107 of these and make the count number 100000,
This length measuring device can be considered to be capable of measuring length in units of 0.01 μm. Based on this principle, in order to keep the error to 0.01 μm or less in the range of 0 to about 160 mm, K may be thinned out according to the rules shown below. That is, m
Start measuring the length from o and thin out the 91st pulse.

(11) The next 91/# Rusu and the next 91
The pulse number and the next 92/4 pulse are thinned out.

(Repeat (ii) 6 times.

Repeating (1) to (l!l) below 0ψ.

FIG. 1 shows an embodiment of the present invention. Laser length measuring device 201
Length measurement from/? The pulse is input to the thinning control counter 202. The output data of the counter 202 is compared with the output data from the decimation number control circuit 203 in a converter 204 .

In the control circuit 203, the value obtained by subtracting 1 from the number to be thinned out in order to execute the control in (1) and (11) above, that is, 9
1/# If you want to thin out the Rusu eyes, use 90.92/4' If you want to thin out the Rusu eyes, set Vi91 to Con/4 depending on each case.
' Output to the controller 204. As a result, the y-t circuit 205 is closed for the thinned-out 9 pulses, and no data is input to the position measurement counter 206. On the other hand, the thinning out! Since the pulse resets the counter 202, the counter output becomes O and does not match the output from the control circuit 203. As a result, the r-to circuit 205 is not opened, and the pulses other than the thinning pulses are input to the counter 206. As described above, the counter 206 can be regarded as a counter in units of 0.01 μm, and its output is sent directly to the charged beam exposure device 207 without going through a memory or the like.

Although FIG. 1 shows only one direction, that is, the direction in which the output of the counter 206 increases, in an actual charged beam exposure apparatus, it is necessary to realize the opposite direction as well. However, in any case, it is clear that the scale can be significantly reduced compared to using memory. Incidentally, assuming that the length measurement range is θ to 160, more than 1000 elements are required when using a memory, but according to the present invention, it can be configured with a scale of about 1/10 of that.

Note that the present invention is not limited to the embodiments described above. Even if the laser used is different, as long as the wavelength division value can be set to a value slightly smaller than the required LSI design unit, this can be done simply by changing the thinning number setting of the control circuit 203 in Figure 1. The invention is applicable.

(Effects of the Invention) As described above, the present invention provides a radar length measuring device that can perform small-scale, high-speed unit conversion without using a large-scale, high-speed memory unlike conventional devices. can be provided.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an apparatus for explaining one embodiment of the present invention,
FIG. 2 is a configuration explanatory diagram showing a conventional laser length measuring device. 101.201... Laser length measuring device, 102,206.
...Length measurement counter, 103...Memory for unit conversion,
104-0.00989 Data in Am, 105
- Data in units of 0.01 μm, 106, 207... Charged beam exposure device, 202... Counter for thinning control, 203... Thinning number control circuit, 204... Comparator, 205... Dart circuit.

Claims (1)

[Claims] By configuring a laser length measuring device, a circuit that thins out the length measurement pulses from the laser length measuring device according to a certain rule, and a counter that coefficients the thinned out pulses, it is possible to measure units of integer fractions of the laser wavelength. A laser length measuring device characterized by performing unit conversion of length data.