JPH056340B2 - - Google Patents

Description

Detailed Description of the Invention The present invention measures the height of the surface of a material to be exposed, and determines the amount of deflection, deflection distortion, and direction of the optical axis of the electron beam projected onto the material in accordance with the measured height. The present invention relates to a method of correcting the imaging position (focal length of a projection lens) and performing exposure.

Irradiating the surface of the material to be exposed with light passing through the slit, and detecting the position of the slit image formed by the light reflected by the surface of the material to be exposed by a detection means using a photoelectric detector. A signal representing the height (position in the optical axis direction) of the surface of the material to be exposed is obtained, and the exposure is performed by correcting the deflection gain of the electron beam irradiated to the material to be exposed using this signal. (Special Application No. 136161, 1982).
If such a method is used, the height of the surface of the material to be exposed can be measured without contact, and there will be no adverse electromagnetic influence on the electron beam exposure system. However, in such conventional methods, the height of only one point on the surface of the material to be exposed can be measured at a time, so one point ( For example, measure the height of the center point of the field,
Exposure was performed on the assumption that the heights of all subfields within this field were equal to the height of this point. However, in recent years, exposure using electron beam exposure equipment with small work distance has begun to be performed, and in such equipment, the deflection angle of the electron beam must be widened for exposure, making it difficult to If the height of the surface deviates from a predetermined height, exposure accuracy will be greatly affected, making it impossible to perform highly accurate exposure.

In order to solve such problems,
In the prior art described in Publication No. 60205, the light that has passed through the slit is guided to a first imaging lens and irradiated obliquely onto the surface of the material to be exposed, thereby forming a slit image on the surface of the material to be exposed. , directing the light reflected by the surface of the material to be exposed to a second imaging lens to guide the image of the slit image to a photoelectric position detector, and detecting the material to be exposed based on the signal from the photoelectric position detector. The height of the surface is detected and the amount of deflection of the electron beam is corrected based on this height information to improve exposure accuracy. However, with such conventional technology, it is not possible to simultaneously measure the heights of multiple locations within one deflection field, so the height of the deflection field can be determined using the height measurement data of one location within one deflection field. As a representative example, it is necessary to perform exposure with insufficient accuracy based on coarse height measurement data, or to perform multiple measurements within one deflection field to improve accuracy but with low throughput exposure. .

Furthermore, in the conventional technique described in Japanese Utility Model Application Publication No. 57-140734, a plurality of electrostatic height detectors are provided, thereby making it possible to simultaneously measure the heights of multiple locations on the surface of the material to be exposed. However, since electrostatic height detectors require a relatively large installation space, it is not possible to install multiple detectors in a narrow area. It is not possible to measure the height of a location at the same time.

The present invention solves these conventional drawbacks and provides an electron beam exposure method that can measure the heights of multiple locations within one deflection field at once, thereby performing exposure with high precision and high throughput. The purpose is to

Therefore, in the present invention, a slit plate having a plurality of slits is irradiated with light from a single light source, and a plurality of light beams passing through each of the plurality of slits are
The slits are irradiated obliquely toward the surface of the material to be exposed through an imaging lens to form an image of each of the slits near the surface. The second ray bundle
The slit images are guided to an imaging lens, and each slit image is focused on an object surface of a projection lens, and a plurality of light beams from the images formed on the object surface are transmitted by the projection lens to a plurality of photoelectric position detectors. The amount of deflection and/or deflection distortion of the electron beam that is formed on the surface of the corresponding detector and irradiated onto the material to be exposed based on the signal representing the position of each slit image from each photoelectric position detector. Alternatively, the electron beam exposure is performed by correcting the imaging position in the optical axis direction.

Embodiments of the present invention will be described in detail below based on the drawings.

FIG. 1 is for showing an example of an apparatus for implementing the present invention. In the figure, 5 is a lamp serving as a light source, and light 6 from this lamp 5 is incident on a light shielding plate 8. As shown in FIG. 2, this light shielding plate 8 is provided with first, second, and third slits Sa, Sb, and Sc. Light 6a, 6b, 6c transmitted through these slits Sa, Sb, Sc enters a filter 9. This filter 9 is for removing wavelength components of the light from the lamp 5 that tend to expose the resist coated on the material 1 to be exposed. The light transmitted through the filter 9 is focused by the imaging lens 7, and the slit is formed near the surface of the material 1 to be exposed.
Connect images Pa, Pb, and Pc of Sa, Sb, and Sc. these statues
Each of the light beams from Pa, Pb, and Pc is reflected at three points Ga, Gb, and Gc within one deflection field on the surface of the material 1, indicated by Ga, Gb, and Gc in FIG. incident on . Incidentally, in FIG. 3, the areas demarcated by dotted lines indicate subfields. The imaging lens 10 is used to form virtual images Pa′, Pb′, and Pc′, which are formed at points symmetrical to the images Pa, Pb, and Pc with respect to the surface of the material 1 to be exposed, on the object surface of the projection lens 11. It's a lens. Projection lens 11
These images are transmitted to semiconductor position detectors 12a and 12, respectively.
This is a lens for forming an image on the detection planes b and 12c. Each semiconductor position detector 12a, 12b, 12
The output signals of c are transmitted through amplifiers 13a, 13b, 1
3c and AD converters 14a, 14b, and 14c to the electronic computer 15. In this semiconductor position detector, for example, when light enters one point on a one-dimensionally formed semiconductor surface constituting the detector, two currents are extracted that are inversely proportional to the distance of the incident point from both ends of the semiconductor. , a type that outputs a position detection signal depending on the magnitude of these two currents is used. Exposure information for exposing the exposed material 1 is stored in this computer 15, and based on this exposure information, the computer 15
generates a deflection signal. This deflection signal is supplied to the deflector 3 via a deflection distortion correction memory 4.
The electronic computer 15 includes the semiconductor position detector 12a,
The height of each subfield of one deflection field to be exposed is interpolated and calculated based on the height information of the three points Ga, Gb, and Gc in the one deflection field supplied from 12b and 12c, and the height of each subfield of the one deflection field to be exposed is calculated by interpolation. Based on the information representing the height of each subfield, when exposing each subfield, a correction signal for correcting the exposure position deviation based on the deviation from the height reference is sent to the deflection distortion correction memory 4. supply

Now, the points Ga, Gb, Gc on the surface of the exposure material 1
Each position detector 1
The positions of the images of the slits formed on the surfaces 2a, 12b, and 12c change because the positions of the virtual images Pa', Pb', and Pc' change when the heights of the measurement points Ga, Gb, and Gc on each surface change. each semiconductor position detector 12
The position detection signals from a, 12b, and 12c are
It represents the heights of Ga, Gb, and Gc (more precisely, the measurement point will move if the height is different, but this is ignored). Position detector 12 indicating the height of each point Ga, Gb, Gc
The output signals from a, 12b, 12c are sent to the amplifier 13.
a, 13b, 13c, and further AD
After being converted into a digital signal by a converter, it is supplied to the electronic computer 15. The electronic computer 15 interpolates the height of each subfield within the deflection field based on pre-stored data representing the coordinates of each point Ga, Gb, Gc and the supplied height signal. Based on the calculated information representing the height of each subfield, a different correction signal is generated each time each subfield is exposed so as to cancel out the exposure position deviation due to the deviation from the height reference. and supplies it to the deflection distortion correction memory 4. When performing actual exposure, the correction signal from this deflection distortion correction memory 4 is read out and the deflection amount of the electron beam 2 is corrected, so that the electron beam 2 is irradiated at the correct position and each subfield is Exposed to a predetermined position with high precision.

In the above-mentioned embodiment, the electron beam irradiation position is corrected based on the signal representing the height of each subfield position, but this also applies when correcting the imaging position in the optical axis direction. The invention is equally applicable.

Furthermore, in the embodiments described above, the correction signal is supplied to the deflection distortion correction memory to adjust the exposure position to correct the electron beam irradiation position.
The deflection signal itself output from the electronic computer may be corrected.

Further, the photoelectric position measuring means for measuring the position of the slit image is not limited to a semiconductor position detector, and for example, a photo sensor array may be used. Furthermore, the slit provided in the light-shielding plate does not necessarily need to be surrounded by the light-shielding plate, and may be any slit that can form a slit image or an edge image on the position detector.

As is clear from the above explanation, in the present invention, the heights of multiple points within one deflection field are measured at once, and the irradiation position of the electron beam and/or the optical axis direction is determined according to the exposure position. Since the image position can be finely corrected for exposure, even when exposure is performed using an exposure apparatus having an electron optical system with a short work distance, exposure can be performed with high precision in a short time.

Furthermore, in the present invention described above, since a plurality of slit images are projected onto each position detector using a single optical system, an apparatus for simultaneous height measurement at multiple locations within one deflection field is required. can be placed in a relatively small space.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of an apparatus for carrying out the present invention, FIG. 2 is a diagram showing details of the light shielding plate shown in FIG. 1, and FIG. 3 is a diagram showing one deflection field to be exposed. FIG. 3 is a diagram for explaining a plurality of height measurement points. 1: material to be exposed, 2: electron beam, 3: deflector,
4: Deflection distortion correction memory, 5: Lamp, 6a, 6
b, 6c: ray, 7, 10: imaging lens, 8: light shielding plate, Sa, Sb, Sc: slit, 9: filter,
11: Projection lens, 12a, 12b, 12c: Semiconductor position detector, 13a, 13b, 13c: Amplifier, 14a, 14b, 14c: AD converter, 1
5: Electronic computer, Ga, Gb, Gc: Position detection point.

Claims (1)

[Claims] 1 Light from a single light source is irradiated onto a slit plate having a plurality of slits, and a plurality of light beams passing through each of the plurality of slits are directed onto the surface of the material to be exposed through a first imaging lens. A plurality of light beams reflected within one deflection field of the surface as a result of the irradiation are guided to a second imaging lens to form an image of each of the slits near the surface. A slit image is formed on the object surface of the projection lens, and a plurality of light beams from the image formed on the object surface are directed by the projection lens to the surface of a corresponding one of the plurality of photoelectric position detectors. The amount of deflection and/or deflection distortion of the electron beam and/or the imaging position in the optical axis direction of the electron beam that is irradiated onto the material to be exposed based on the signal representing the position of each slit image from each photoelectric position detector. An electron beam exposure method characterized in that electron beam exposure is performed by correcting.