JPS63217627A - Electron beam lithography device - Google Patents

Abstract

PURPOSE:To enable the writing with high accuracy to be performed without deteriorating the throughput by a method wherein an induction compensating circuit to supply a main focus coil with current compensating an electromagnetic induction current generated in a main focus coil by the changing dynamic focus compensation coil is made in the title device. CONSTITUTION:When a dynamic focus compensation coil 13 is supplied with focus compensation current 51 at a time t1, a main focus coil 4 is supplied with induction current 52. On the other hand, induction current 53, which has the same intensity as, but in the reverse direction to, said current 52 produced by the focus compensation current 51 in the main focus coil 4, is produced through an induction compensating circuit 14 and flows into the main focus coil 4. In other words, the magnetic induction current 52 generated in the main focus coil 4 is offset by the induction current 53 flowing from the induction compensating circuit 14 to make main focus coil current 54 equivalent to the subjected to no change. Resultantly, even if the dynamic focus compensating circuit 13 is changed, the main focus coil 4 is apparently subjected to no electromagnetic induction current generated. Through these procedures, the writing accuracy can be increased without deteriorating the throughput.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electron beam lithography system, and particularly to an electron beam lithography system suitable for high-speed, high-precision lithography.

[Conventional technology]

The prior art will be explained using FIG. 5. Electrons 4!2 emitted from the electron gun 1 are converged by a converging lens 3 and focused onto a sample 5 by a principal focus coil 4. On the other hand, the drawing data is sent from the CPU 6 to the deflection signal generator 7, which applies polarization signals corresponding to the drawing pattern to the electrostatic deflector 8 and the electromagnetic deflector 9, thereby controlling the electron beam 2. Once the position of the electron beam 2 is determined, a signal is given to the blanker 10 to turn the electron beam 2 on and off to expose the sample 5. When the drawing of the determined area is completed, the sample 5 is transferred via the stage control circuit 11.
The stage 12 on which the image is placed is moved to the next position.

Next, the drawing method will be explained with reference to FIG. wafer 21
The upper chip 22 is divided into arbitrary fields 23. In the example shown in FIG. 6, one chip is composed of four fields. A field is an area where an electron beam is controlled by electromagnetic deflection.

Field 23 is divided into small areas called subfields 24. First, subfield (2) is drawn at high speed using electrostatic deflection, and then subfield (2) is positioned using electromagnetic deflection. At this time, in order to compensate for the defocus of the electron beam that occurs, a compensation current is passed through the dynamic focus compensation rate coil 13 shown in FIG. After the dynamic focus compensation signal sent to 13 is sufficiently settled, subfield ■ is drawn by electrostatic deflection by electrostatic deflector 8. This is repeated after subfield ■ to draw the entire field a.Next After moving the stage 12 and positioning field b, field b is drawn in the same way.The function of the dynamic focus compensation coil 13 is to change the focal length of the principal focus coil 4, so to speak. It is installed in close proximity to the main focus coil 4. Therefore, the magnetic flux generated when a compensation current is passed through the dynamic focus compensation coil 13 interlinks with the main focus coil 4, causing a magnetic induction current in the main focus coil 4. to occur.

The electron beam 2 is deflected and focused by the magnetically induced current generated in the main focus coil 4, and the drawing accuracy is noticeably reduced. Furthermore, if writing is performed after the magnetically induced current has sufficiently stabilized in order to improve the writing accuracy, it will take approximately 500 μs for the magnetically induced current to settle, resulting in a significant decrease in throughput.

[Problems that the invention attempts to solve]

According to the above-mentioned conventional technology, the magnetic flux generated when a compensation current is passed through the dynamic focus compensation coil is used as a main focus compensation coil.

generates a magnetically induced current in the main point coil,
There is a problem in that the electron beam is deflected and focused, which significantly reduces drawing accuracy.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electron beam lithography apparatus that can compensate for magnetically induced current generated in a main focus coil and improve lithography accuracy without reducing throughput.

[Problems to be solved]

The above-mentioned objective (i) is achieved by a configuration including an induction compensation circuit that flows into the main focus coil a current that compensates for an electromagnetic induction current generated in the main focus coil due to a change in the dynamic focus compensation coil current.

[Effect]

In the present invention, a current of the same amount and in the opposite direction as the magnetic induction current generated in the prime focus coil is caused to flow into the prime focus coil due to a change in the excitation current of the dynamic focus compensation coil, so that the magnetic induction generated in the prime focus coil is The induced current can be compensated for, and writing accuracy can be improved without reducing throughput.

〔Example〕

The present invention will be explained in detail below with reference to the embodiments shown in FIGS. 1, 2, and 4, and FIG. 3.

FIG. 1 is a schematic diagram showing an embodiment of an electron beam lithography apparatus according to the present invention. In FIG. 1, the same parts as those in FIG. In FIG. 1, a conventional principal focus coil 4 and a dynamic focus compensation coil 13 are shown.
An induction compensation circuit 14 is provided between the electron beam 2 and the electron beam 2 emitted from the electron gun 1 as before.
The sample 5 is exposed to light. At the same time as the subfield positioning signal is output to the electromagnetic deflection signal 9 (tl
), a focus compensation current flows through the dynamic focus compensation coil 13.

FIG. 2 is a circuit diagram showing a detailed example of the main focus coil section of FIG. 1. 4 is the main focus coil.

13 is a dynamic focus compensation coil, and 14 is an induction compensation circuit.

FIG. 3 is a diagram showing temporal changes in the coil current in FIG. 2. When the focus compensation current 51 flows through the dynamic focus compensation coil 13 at time L1, the main focus is A magnetically induced current 52 flows through the coil 4 . On the other hand, due to the focus compensation current 51, an induction current 53 of the same amount and in the opposite direction as the magnetic induction current 52 generated in the main focus coil 4 is generated in the induction compensation circuit 14 as shown in FIG. 3(b), and this is the main focus. It flows into the focusing coil 4. In other words, the magnetically induced current 52 generated in the main focus coil 4 is canceled out by the induced current 53 flowing from the induction compensation circuit 14, and the main focus coil current 54 does not change as shown in FIG. 3(c). will be equivalent to

As described above, even if the dynamic focus compensation current changes.

No apparent electromagnetic induction current is generated in the main focus coil 4, and drawing accuracy can be improved without reducing throughput.

FIG. 4 is a circuit diagram corresponding to FIG. 2 showing another embodiment of the present invention, and in FIG. 4, the induction compensation circuit 14 of FIG.
A differentiating circuit 15 is provided as a differential circuit, and the same effect can be obtained even in this case.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to compensate for the electromagnetic induction current to the main focus coil due to changes in the dynamic focus compensation current, so there is no need to set the induction current, thereby reducing throughput. This has the effect of enabling high-precision drawing without deterioration.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of the electron beam lithography apparatus of the present invention, a wiring diagram showing an embodiment of the main focus coil section in FIG. 2,
Fig. 3 is a diagram showing the temporal change in the coil current in Fig. 2, Fig. 4 is a circuit diagram corresponding to Fig. 2 showing another embodiment of the present invention, and Fig. 5 is a diagram using conventional electron beam drawing. Configuration diagram of the device,
FIG. 6 is an explanatory diagram of the drawing method. DESCRIPTION OF SYMBOLS 1...Electron gun, 2...Electron beam, 3...Converging lens, 4...Primary focus coil, 5...Sample, 6...CP
U, 7... Deflection signal generator, 8... Electrostatic deflector, 9
... Electromagnetic deflector, 10... Blanker, 11... Stage control circuit, 12... Stage, 13... Dynamic focus compensation coil, 14... Induction compensation circuit, 15...
Differential circuit, 51... Focus compensation current, 52... Magnetic induction current, 53... Induction current, 54... Main focus coil current. Figure 2 (C)

Claims (1)

[Claims] 1. means for generating an electron beam, means for converging the electron beam, a main focus coil for focusing the electron beam focused by the means onto a sample, and the focused electron beam on the sample; a dynamic focus compensation coil that focuses the electron beam on the sample according to the amount of deflection of the electron beam; and a blanking means that turns the electron beam on and off on the sample. The electron beam lithography apparatus is characterized by being provided with an induction compensation circuit that flows into the main focus coil a current that compensates for an electromagnetic induction current generated in the main focus coil due to a change in the dynamic focus compensation coil current. Electron beam lithography equipment.