JPS6040186B2 - Magnetic field forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for forming a magnetic field based on given digital information.

Generally, it is known that a digital-to-analog converter is used for control to obtain a certain analog quantity corresponding to digital information, and a DA converter is used to generate a desired magnetic field.

Generally, the response characteristics of commercially available DA converters deteriorate as the number of bits of digital information increases. It is difficult to enter. Therefore, an object of the present invention is to obtain an intended magnetic field forming device using a DA converter with a relatively small number of bits of digital information and good response characteristics.

Hereinafter, the present invention will be explained in detail using the drawings.

The present invention is characterized by the method of forming a magnetic field, and can be applied to an electron beam exposure apparatus as shown in FIG. Referring to FIG. 1, FIG. 1a shows a schematic structure of an electron beam exposure apparatus to which the present invention can be applied, and FIG. 1b shows a cross-sectional shape of the electron beam at a corresponding portion. In Fig. 1a, 1, 2, and 3 are respectively cathodes, grids, and anodes that constitute an electron gun, and 4 is a magnetic field forming device (4) for planking by changing the direction of the electron beam with a magnetic field during unnecessary periods. (hereinafter referred to as a deflection device), 5 is a converging lens, 6 is a first aperture, 7 is a rotation control lens for controlling the rotation of the electron beam around the axis, 8 is an electron lens, and 9 is a 2 a deflection device (deflector) for controlling the imaging position of the image of the first aperture 6 formed on the aperture 10, 11 a rotation control lens, 12 a binding lens, 1
Reference numeral 3 indicates a deflection device (deflector) for displacement, and 14 indicates a sample coated with a resist, such as a semiconductor wafer. The electron beam transmitted through the rectangular hole of the first aperture 6 and shaped into a rectangular pattern 15 is passed through the electron lens 8 to the second aperture 10.
A rectangular image 16 of the first aperture is formed above. rectangular image 1
6, the imaging position is controlled by the deflection device 9, and the second aperture 1
A cross-sectional shape 1 of a predetermined size is partially transmitted through the rectangular hole 17 of 0.
The rotation, size, and position of the Shigeko beam around the axis are further controlled by a rotation control lens 11, a converging lens 12, and a positional deflection device 13, so that the electron beam with a desired pattern 19 is placed at a predetermined position on the wafer 14. It is irradiated as
FIG. 2 is a diagram showing a deflector (deflector) which is a conventional magnetic field forming device.

In the figure, 20 is a register in which digital information is set;
21 is a DA converter, 22 is an amplifier, 23 and 23' are coils for swinging the electron beam in the Y direction, and 24 and 24' are coils for swinging the electron beam in the X direction. Digital information for swinging in the Y direction is given to the register 20'.
A current flows through the coil 23 by the DA converter 21 and the amplifier 22, and a magnetic field corresponding to digital information is formed. Therefore, if digital information for controlling the electron beam is set in the register 20', the electron beam will be controlled by a magnetic field corresponding to the digital information. The same can be said for the aircraft regarding the x direction. Incidentally, in an electron beam exposure apparatus, in order to expose the wafer 14 with electron beams, one chip is divided into a plurality of blocks, and exposure is performed for each block.

In other words, there is a small movement within one block, and then a large one.
Move by a block and make small movements within that block. Therefore, for small movements, the lower bits of the DA converter 21 are frequently updated, and the upper bits are updated when moving by one block. A large difference between the upper and lower limits of the current flowing through the coil 23 increases the burden on the amplifier 22, which is disadvantageous in terms of design.

Furthermore, in the case of a DA converter, an increase in the number of input bits causes a corresponding drop in the response characteristics of the output voltage, which is an analog quantity. FIG. 3 shows an embodiment of the invention. In the figure, the same symbols as in Fig. 2 indicate the same ones as in Fig. 2. 23-1 is a variable coil that forms a magnetic field with a strength that changes in an analog manner, and 23-2 and 23-3 are pre-assembled coils. Fixed coils 25 and 26, which form a magnetic field of a defined predetermined strength, are switches. That is, of the digital information given to the register 20', a magnetic field is formed in the variable coil 23 by the DA converter and the amplifier 22 corresponding to only the lower 6 bits.

When YES is 1'' for the upper two bits, the switch 25 and/or 26 becomes conductive, and a magnetic field corresponding to the weight of the bit is formed in the fixed coils 23-2 and/or 23-3. Information in the register 20 A high voltage may be used to form a magnetic field with a weight corresponding to each bit of , may be wound overlappingly on the same iron core, etc., or may be wound as separate coils.In short, it is sufficient if the addition is performed as a magnetic field.According to the present invention, one chip of a wafer to be exposed with an electron beam is divided into, for example, 16 blocks. If the data is divided into four parts (four parts in the Y direction and four parts in the x direction), the block designation is performed using the upper two bits.

Therefore, a 6-bit DA converter is sufficient for small movements within a block, and the upper and lower limits of its output are small and the response characteristics are good, and the amplifier 22 also has the advantage of being easy to design. Incidentally, when a fixed coil is used for movement between blocks in this way, a high switching speed is not required, so it is of course possible to configure the switch using a relay or the like.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an electron beam exposure apparatus to which the present invention can be applied, FIG. 2 is a conventional magnetic field forming apparatus, and FIG. 3 is an embodiment of the present invention. In the figure, 1 is a cathode, 2 is a grid, 3 is an anode, 4 is a magnetic field forming device (deflector) for planking, 5 is a converging lens, 6 is a first aperture with a rectangular hole, and 7 is for rotation control. lens, 8 is a converging lens, 9 is a polarizer for controlling the size of the rectangular pattern electron beam, 1st and 2nd
diaphragm, 11 is a rotation control lens, 12 is a converging lens, 1
3 is a polarizing device for pupil determination, 14 is a wafer, and 15 is a first
16 is the image of 15; 17 is the rectangular hole of the second diaphragm; 18 is the electron beam after passing through the second diaphragm; 19 is the pattern to be printed on the wafer; is a DA converter, 22 is an amplifier, 23-1 is a variable coil, and 23-2 and 23-3 are fixed coils. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. In a magnetic field forming device that deflects an electron beam in the X region in the Y direction in block units and forms a deflection magnetic field for varying the electron beam within the block unit in accordance with a plurality of bits of digital information, the digital The deflection magnetic field is formed by a variable coil that uses one part of the information to obtain a magnetic field of different strength in an analog manner, and a fixed coil that obtains a magnetic field of a predetermined strength using another part of the digital information. A magnetic field forming device characterized in that the magnetic field of the fixed coil deflects the electron beam in block units, and the variable coil deflects the electron beam in block units.