JP2544588B2 - Calibration member for length measurement and manufacturing method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a calibration member for length measurement and a method of manufacturing a calibration member for performing dimension calibration for dimension measurement, and particularly to electron beam length measurement corresponding to a micro dimension of submicron or less. The present invention relates to a suitable length measuring member and a method for manufacturing the same.

[0002]

2. Description of the Related Art A conventional apparatus is disclosed in Japanese Patent Laid-Open No. 59-12314.
As described in No. 9, there was no dimension calibration function, and it had only the function of moving the sample observation point. Further, as a member for measuring the length, Japanese Unexamined Patent Publication (Kokai) No. 61-292505 discloses a sawtooth measurement reference body manufactured by anisotropic etching.

[0003]

Although the above-mentioned prior art discloses a sawtooth diffraction grating, the S / N of the detection signal is not disclosed.
There was a problem about.

An object of the present invention is to always add high dimensional accuracy and stability by disposing an absolute calibration member on the moving stage.

[0005]

The above object is achieved by disposing a diffraction grating for absolute calibration guaranteed by diffraction angle measurement (optical measurement) on a moving stage.

That is, the absolute calibration diffraction grating is
It is indispensable that the SN ratio of the secondary electron signal at the time of scanning the electron beam is high and the dimension value is assured by another measuring means with a fine dimension of μm or less.

In order to achieve the above object, a laser interference exposure method capable of patterning a dimension of 1 μm or less with high precision, and a Si or compound semiconductor (110) substrate capable of producing a fine vertical section structure with a high aspect ratio are provided. By combining wet anisotropic etching, (11
A dimension-correcting diffraction grating having a vertical sectional structure formed by the 1) plane and capable of obtaining a high SN ratio of secondary electron signals was produced. Since the present diffraction grating has a constant pitch, the above-mentioned object can be achieved by assuring the pitch dimension from the diffraction angle by making a single-wavelength light source enter and diffract. Further, the guarantee of the pitch dimension can be achieved by the correspondence between the stage movement amount and the pitch movement even after the stage is assembled.

[0008]

The diffraction grating patterned on the (110) Si or (110) compound semiconductor substrate by the laser interference exposure method and the wet anisotropic etching can be processed up to about 0.1 μm pitch, and its accuracy is It has a feature that it can guarantee up to 0.001 μm by measuring the diffraction angle. By placing this diffraction grating on the moving stage and measuring the diffraction grating before measuring the sample, absolute calibration can be performed at any stage. Also, by installing the diffraction grating in a direction perpendicular to the stage movement direction, the absolute dimension value can be guaranteed even after the device is installed in the device due to the correspondence between the stage movement amount and the number of pitches of the moved diffraction grating. It will be possible.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS.
This will be described below.

FIG. 1 shows a schematic structure of the present invention. The moving stage moves in the X direction, and the moving amount is measured by a laser interferometer. The diffraction grating used for absolute calibration was obtained by anisotropic etching of a isopropyl alcohol saturated KOH aqueous solution (30 wt%, 80 ° C.) on a (110) Si substrate by patterning by interference exposure using a He—Cd laser. Pitch 0.28 μm, depth 1 μm
The pitch dimension accuracy is 0.0 from the diffraction angle measurement.
It was 1 μm or less. (FIG. 2) The secondary electron waveform obtained when the diffraction grating was scanned with an electron beam had a good SN ratio as shown in FIG.

Next, the accuracy was guaranteed to be 0.016 μm from the pitch dimension moved by moving the stage while fixing the electron beam and the stage movement amount by the laser interferometer. As described above, the absolute dimensions are assured with the accuracy of 0.01 μm by the two different measuring methods.

In the present embodiment, the case where the stage moves only in the X direction has been described, but the same effect can be obtained if the diffraction grating used in the present embodiment is installed on the stage in the direction perpendicular to the moving direction also in the Y direction. It goes without saying that you can get

[0013]

According to the present invention, the absolute measurement of the dimension measurement can be performed by the standard sample (diffraction grating) in the stage, so that the absolute dimension which has never been realized can be guaranteed with high accuracy. Also, the absolute size of the standard sample is always assured with high accuracy by optical measurement before installation and stage movement amount measurement method after installation.

Furthermore, since the diffraction grating made of the (110) Si or (110) compound semiconductor substrate used in the present invention has a deeper groove than other diffraction gratings, the secondary electron signal is excellent and Since it is less affected by contamination by electron beam irradiation and does not change with time, it can be used semipermanently.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of an embodiment of the present invention.

FIG. 2 is a sectional view of a diffraction grating used in the present invention.

FIG. 3 is a diagram showing a secondary electron signal waveform obtained from the diffraction grating.

[Explanation of symbols]

1 ... Sample, 2 ... Stage drive motor, 3 ... Sample moving stage, 4 ... Laser interferometer, 5 ... Diffraction grating, 6 ... Electron beam, 7 ... (110) Si substrate, 8 ... (111) Si
Crystal plane.

Claims (7)

(57) [Claims] 1. An uneven pattern in which the absolute value of the pitch dimension is specified by optical diffraction angle measurement, and (11
A calibration member for length measurement, comprising a semiconductor member having a (0) plane and a (111) plane. 2. The uneven pattern has a (110) plane and a (1) plane.
11. The length-measuring calibration member according to claim 1, wherein the calibration member comprises a 11) plane and forms a diffraction grating having a vertical sectional structure. 3. The length-measuring calibration member according to claim 1, wherein the semiconductor member is made of a silicon substrate, and a surface orientation of the surface is a (110) plane. 4. The length-measuring calibration member according to claim 1, wherein the semiconductor member is composed of a compound semiconductor substrate, and a surface orientation of the surface is a (110) plane. 5. A method for producing a calibration member for length measurement, which comprises forming irregularities of a diffraction grating pattern on a surface of a semiconductor substrate having (110) plane and (111) plane by laser interference exposure. 6. The calibration member for length measurement according to claim 5, wherein the diffraction grating pattern is formed by wet anisotropic etching into a vertical cross-section structure consisting of (110) plane and (111) plane. Of manufacturing. 7. The method for producing a calibration member for length measurement according to claim 6, wherein an aqueous potassium hydroxide solution is used for the wet anisotropic etching.