JPS59143322A - Electron beam drawing device - Google Patents

Abstract

PURPOSE:To draw a material to be drawn which includes a part requiring highly accurate drawing with high accuracy as well as to complete the overall drawing in a short time by providing two kinds of electron lenses whose distances from the material are different mutually and by using these lenses with changing over them according to the accuracy of a pattern to be drawn. CONSTITUTION:Electron beam from an electron gun 1 is projected toward a material to be drawn 4 on a stage through an aperture plate 2. A first and a second electron lenses 5 and 6 are arranged along an optical axis of said electron beam and a third and a fourth electron lenses 7 and 8 are arranged under these lenses 5 and 6. An electrostatic deflector 9 is arranged near the lens 7 and an electrostatic deflector 10 is arranged in a lens magnetic field formed by the lens 8. Then induction current is supplied from induction power supplys 11 and 12 through switching circuits 13 and 14 to the lenses 7, 8 and a control system 15 controls the change-over of the lenses 7 and 8 according to accuracy of a pattern to be drawn thereby drawing the material to be drawn 4 with high accuracy and reducing time for the overall drawing.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electron beam lithography system, and in particular, to an electron beam lithography system for lithography at high speed on a material to be lithography which partially has a fine pattern to be lithographically drawn with high precision. The present invention relates to an electron beam lithography system that can perform

[Prior Art] In recent years, research has been conducted into drawing patterns of optical ICs for optical communication using electron beams. The optical circuit section of this IC has a fine structure of several hundred angstroms, so when writing this circuit section, we use an electron optical system that can make the electron beam irradiation diameter extremely small, and further reduce the influence of deflection aberration. In order to do this, the deflection range of the electron beam is narrowed. Therefore, the number of time-consuming mechanical movements of the material to be drawn becomes extremely large, and it takes a very long time to write the entire IC circuit.

[Object of the Invention] The present invention has been made in view of the above points, and an object of the present invention is to provide an electron beam lithography apparatus that can draw at high speed a material to be drawn having a portion to be drawn with high precision. The purpose is

[Structure of the Invention] The electron beam lithography apparatus based on the present invention includes first and second electron lenses arranged at different distances from each other to the material to be drawn, each of which independently operates as a final stage focusing lens, and the material. a deflection means for changing the electron beam irradiation position on the top;
and means for selectively operating either the first or second electron lens depending on the figure drawn on the material.

[Example] An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

In FIG. 1, reference numeral 1 denotes an electron gun, and an electron beam generated from the electron gun passes through an aperture plate 2 for blanking and is irradiated in 4 directions of a material to be drawn on a stage 3. First and second electron lenses 5.6 are arranged along the optical axis of the electron beam, and third and fourth electron lenses 7.8 are arranged below the electron lens 5.6. ing. A first electrostatic deflector 9 is arranged close to the third electron lens 7, and a second electrostatic deflector 10 is arranged in the lens magnetic field formed by the fourth electron lens 8. However, both of the deflectors can deflect the electron beam in the X and Y directions, respectively.

The first and second electron lenses 7°8 are each connected to an excitation power source 1.
A desired excitation current is supplied from 1.12 through a switch circuit 13.14, which is turned on by a signal from a control system 15 such as a monitor.
Or it is turned off. A deflection signal from the control system 15 is applied to the first and second electrostatic deflectors 9 and 10.
It is fed via converters 16.17.

The stage 3 is driven by a stage drive mechanism 18 that is controlled by the control system 15.

generated based on the irradiation of the electron beam to the drawing material 4,
For example, the reflected electrons are detected by the detector 19, and the detection signal is supplied to the control system 15 via the A/D converter 20. Note that 21 is a blanking deflector, to which a blanking signal from the control system 15 is supplied via a DA converter 22.

Fig. 2 is a conceptual diagram of an IC chip T with a side length of 5 mm.A mark M is provided in advance at the corner of the chip T, and the center part of the chip T has a high precision of about several hundred angstroms. A circuit portion such as an optical circuit portion to be drawn is placed, a peripheral portion is placed around the center, and a peripheral circuit portion that does not require precision is placed. The operation of the apparatus shown in FIG. 1 will be explained by taking as an example the case where such a chip T is drawn. The central part of the chip is virtually divided into 25 to 100 fields F+ of 0.1 u on a side, and the peripheral part of the chip is divided into 4 fields F2 of 2 u on a side. When drawing the central part of the chip, in the apparatus shown in FIG.
It is said that As a result, the electron lens 8 has an excitation power source 12
An excitation type 4- current is supplied from the electron lens 8, and the electron lens 8 functions as a final stage electron lens.Since the excitation current from the excitation power supply 11 is not supplied to the electron lens 7, the third electron lens This means that it does not contribute to the focusing effect of the electron beam. The electron beam is focused by the fourth electron lens, but since the distance between the electron lens 8 and the material 4 to be drawn is extremely short, the diameter of the electron beam on the material is, for example, 0.011
It can be made extremely small, about the size of a glume. At this time, the second electrostatic deflector 10 is connected to the D-
A deflection signal corresponding to the pattern to be drawn is supplied via the A converter 17, but the deflection range of the electron beam by the deflection signal is extremely narrowed, and the field F1 is drawn with high precision. After the specific field F1 is drawn, when drawing the adjacent field F+ that should be drawn with high precision, a drive signal is supplied from the control system to the stage drive mechanism 18, and the stage 3 After this movement, the field is drawn with high precision. Although not shown, the movement of this stage is controlled by a system using a laser interferometer, which is well known in this field, and the movement is monitored with high precision to eliminate errors associated with the movement. Corrected immediately. After the prescribed drawing of each field F1 to be drawn in high-grade pox is completed, the surrounding field F2 is drawn, but at this time, the stage is
The electron beam is moved so that the center of the electron beam 2 and the electron beam optical axis substantially coincide with each other. When drawing the field F2 in the peripheral portion, a signal is supplied from the control system to each switch circuit 13, 14, and the switch circuit 14 is turned OFF and the switch circuit 13 is turned ON. As a result, the electronic lens 8
The operation of the electron lens 7 is stopped, and the electron lens 7 functions as the final stage electron lens. In this state, since the distance between the electron lens and the drawing material 4 is relatively long,
The diameter of the electron beam to the drawing material is about 0.2 pm. Furthermore, in this state, a deflection signal corresponding to the pattern to be drawn is supplied from the control system 15 to the electrostatic deflector 9, and the field is drawn. After the drawing of the specific field is completed, the stage is moved by the length of one side of the field F2 by the drive mechanism 18, and the drawing of the adjacent field is performed. When drawing this peripheral part, the electron beam is deflected by a deflector that is relatively far from the material F314, and even with a small deflection angle with little deflection aberration, it is possible to draw a relatively wide range on the material. I can do it.

In this way, in the above-mentioned configuration, the electron beam is focused extremely narrowly by using an electron lens with a short distance to the material for the part of the chip that should be drawn with relatively high precision, and the deflection range of the electron beam is narrowed. For parts of the chip that do not require relatively high precision, an electron lens with a long distance to the material is used to draw on the material with a relatively large diameter electron beam, and the electron beam is deflected by deflection. By increasing the movement range on the material and thereby reducing the time it takes to move the stage, it is possible to draw the entire material at a fast speed even though it is drawing with the necessary high precision. I can do it.

7- As mentioned above, in the embodiment shown in FIG. 1, in the process of drawing in a single chip, one of two sets of electron beam focusing and deflecting systems is used by switching. Therefore, since the optical axes of the two sets of focusing/deflecting systems do not match, it is not possible to connect the patterns between the fields with high precision, so it is necessary to make the two optical axes match precisely. . In the embodiment shown in FIG. 1, therefore, two corners of the chip T are drawn before each field is drawn.
The stage is moved so that the optical axis is located at a mark M formed by a linear mark element on the book. In this state, first, only the third electron lens 7 is excited, and a deflection signal is applied to the first electrostatic deflector 9 to scan the electron beam across the two mark elements. The reflected electrons generated in response to the scanning of the electron beam are detected by the detector 17, and the detection signal is supplied to the control system. Based on the detection signal, the control system 15 determines, based on the known mark element spacing and the deflection signal amount corresponding to the mark element spacing, such that the electron beam is moved by a predetermined amount 8- by a predetermined deflection signal. The amplification system for the deflection signal supplied to the first deflector is adjusted. At this time, the distance If D from the scanning start point of the electron beam to the first mark element position
1 is measured and stored. Next, with the third electron lens 7 de-energized and the fourth electron lens 8 excited, an electron beam is scanned across the two mark elements on the second electrostatic deflector. Such a deflection signal is supplied. The reflected electrons generated in response to the scanning of the electron beam are detected by the detector 19, and the detection signal is supplied to the control system. Based on the detection signal, the control system 15 adjusts the second electron beam so that the electron beam is moved by a predetermined amount by a predetermined deflection signal based on the known mark element spacing and the deflection signal amount corresponding to the mark element spacing. Adjusts the amplification system for the deflection signal supplied to the deflector.

At this time, the distance D2 from the scanning start point of the electron beam to the first mark element position is measured and stored.

The control system 15 controls the measured distance 111f D
1 is calculated as the difference between 02 and 02, but this difference ΔD is
This is the amount of deviation of the optical axis of the set of focusing/deflecting systems. Therefore, for example, after drawing the field F1 in the central part of the chip T with high precision using a focusing deflection system consisting of the fourth electron lens 8 and the second deflector 10, the field F1 in the peripheral part of the depth T is drawn with high precision. ``When drawing the pattern in 2 using a focusing deflection system consisting of a third electron lens and a first deflector,
This is performed by correcting the position signal of the pattern in the field F2 by the amount of deviation ΔD of the optical axis. As a result, the entire chip can be drawn at high speed by connecting the fine patterns in the central part and the patterns in the peripheral part with high precision. Although the above deviation amount ΔD represents the deviation of the optical axis in one direction, in reality, the deviation amount in a direction perpendicular to this direction is also determined using other mark parts.

In the above embodiment, the first and second deflectors 9 and 1o are switched and used depending on the field to be drawn.
However, when the fourth electron lens 8 is excited to perform highly accurate drawing, the first and second deflectors may be used as a two-stage deflection system. Further, although the second deflector 10 is placed within the field 11 of the fourth electron lens 8, it may be placed outside this magnetic field. Furthermore, a single deflector may be used.

Furthermore, although the present invention has been explained using an example of a chip that has a fine structure in the center and draws this part with high precision, when drawing a chip where the part to be drawn with high precision exists in the periphery. The present invention can also be applied to.

[Effect] As detailed above, the present invention provides two types of electron lenses, each having a different distance from the material to be drawn, and switches the electron lenses for use depending on the accuracy of the pattern to be drawn. Because of this structure, even if the material has a part that needs to be drawn with high precision, it is possible to draw the entire part in a short time.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an electron beam lithography apparatus which is an embodiment of the present invention, and FIG. 2 is a diagram illustrating an example of a chip drawn by the apparatus shown in FIG. 1. 11- 1... Electron gun 3... Stage 4... Material to be drawn 7.8... Electronic lens 9.10... Electrostatic deflector 11.12...
・・・・・・Excitation power supply 13.14・・・・・・・・・
Switch circuit 15... Control system 16.17... D-A converter 16...
... Stage drive mechanism 17 ......
Backscattered electron detector patent applicant JEOL Ltd. representative Ito -husband 12- Figure 2

Claims (3)

[Claims] (1) First and second electron lenses arranged at different distances from the material to be imaged, each acting independently as a final stage focusing lens, and a deflection device for changing the electron beam irradiation position on the material. An electron beam lithography apparatus comprising: means for selectively operating either the first or second electron lens according to a figure to be drawn on the material. (2) The electron beam according to claim 1, wherein the deflection means comprises first and second deflection means, and either one of them is used depending on the selection of the first and second electron lenses. drawing device. (3) The deflection means comprises first and second deflection means, and when the first electron lens remote from the material is operated, only the first deflection means is used; Electron beam lithography according to claim 1, in which a two-stage deflection system is constituted by the first and second deflection means when the second electron lens arranged close to each other is operated. Device.