JP2003051437A - Electron beam lithographic method and machine, and mark recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electron beam lithographic method and machine, and a mark-recording method, which can form a fine recording mark or a pattern of a semiconductor element more accurately, under the control of a light exposure quantity. SOLUTION: A blanking function is provided with a blanking function and a light-exposure quantity control function, the functions of which are realized by signal processing or with use of two blanking electrodes. As a result, the exposure light quantity can be corrected, according to a variation in the exposure light quantity caused by width control of a recording mark, and a uniform exposure light density can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam drawing method, a mark recording method and an electron beam drawing apparatus for accurately forming minute recording bits and minute guide grooves of optical and magnetic recording media. The present invention relates to an electron beam drawing method and apparatus for ultra-high density mastering.

[0002]

2. Description of the Related Art In recent years, the progress of information society has been remarkable,
There is a demand for the development of technology capable of storing more information. At present, in the field of research on disk-type file memories, multi-level recording is being promoted along with miniaturization of recording bit diameter. At present, the bit diameter is about 0.4 μm for optical recording, but further improvement is difficult. But 20
In 2002, a large capacity optical disk of 20 to 25 GB will be required. The current capacity is 4.7 GB (recording density about 3 Gb /
in ² ), which is required to be 4 to 5 times this, and a recording density of about 15 Gb / in ² is required. To realize this, it is necessary to realize a recording bit diameter that is less than half the current bit diameter and smaller than 0.2 μm. Along with this, writing /
The beam diameter required for reading is a submicron diameter of around 100 nm. (In this way, minute bits and gaps require a minute pattern of 100 nm or less.)
On the other hand, with the current optical technology, studies are being conducted to see if the beam system can be used for multi-valued recording as it is. With the current technology, the beam diameter is about 250 even if a blue laser (wavelength: 400 nm) and a high NA (NA: 0.95) are used.
nm, which makes it extremely difficult to increase the density.

Therefore, recently, there is an increasing demand for adopting the above-mentioned minute light spot and multi-value recording system. Recent proposals for multi-valued recording are reported in the introduction booklet (conventional technology 1) of the Nanometer Control Optical Disk System Project of the Japan Optical Industry Technology Promotion Association, which is commissioned by the High Energy Development Organization of the Ministry of International Trade and Industry (NEDO). (Seiya Ogawa "Outline of Nanometer Controlled Optical Disc System Project" 1st Next Generation Optical Memory Symposium Presentation Material (Published by Opto-Industrial Technology Advancement Association, November 1999)
1st a month)). The above-mentioned Prior Art 1 shows an example of a 100 Gb / in ² high-density recording system proposed in the project. As this high-density recording method, a multi-value recording method in which one mark has multi-value information of 8 bits has been proposed. By the way, the distance between the center positions of the marks is 3
The thickness is 80 nm and the track interval is 140 nm, which is extremely small. In multi-level recording, the length of the tangential direction of the mark is set to 100 Gb / by setting the minimum length from the position set by the system within the mark and setting 16 levels (4 bits) in 7 nm increments.
in ² is realized. This method is called edge modulation recording. Here, since the edge modulation recording is performed before and after the position set in the system in the mark, one mark can have doubled 8 bits of information. However, in this case, it is necessary to set the bit length accuracy to 1 nm or less.

Further, as a conventional technique of an electron beam drawing apparatus, "Y. Kojima et al.
Physcis, Volume 37, page 2137 "(Prior Art 2)
The outline is known in.

Specifically, in FIG. 2, a simplified diagram of the electron optical system is shown on the left side, and a blanking circuit 14 is shown on the right side.
The control system including is shown. The electron optical system is the electron gun chip 2
The electron beam 10 obtained by field emission from 7 is narrowed down by the condenser lens 2 and further narrowed down on the sample 6 by the objective lens 22 to obtain a beam spot on the order of nanometers. At this time, the center of the blanking electrode 8 should coincide with the crossover point formed by the condenser lens 2. Further, the blanking signal 20 output from the control system 12 is converted into a signal that allows the electron beam 10 to be appropriately blanked through the amplifier 32, and is input to the drive circuit 24 to drive the blanking electrode 8. At this time, an aperture 28 is provided to cut off the electron beam 10 instantaneously. As a result, a blanking characteristic with a high rise can be obtained.

[0006]

However, it is gradually becoming clear that the multi-value recording method described in the prior art 1 has a low feasibility and that another multi-value information recording method is required.

[0007] Therefore, we have a Japanese Patent Application No. 2000-1950.
In '96, it was proposed to easily realize high density recording by giving multi-valued information to the width. In this case as well, an accurate bit width size is similarly required.

On the other hand, the prior art 2 does not describe the control of the mark width that gives multi-valued information, and does not consider the exposure amount control.

An object of the present invention is to control the exposure amount based on
An object of the present invention is to provide an electron beam drawing method, an apparatus therefor, and a mark recording method capable of forming a minute recording mark or a pattern of a semiconductor element more accurately.

Another object of the present invention is to provide a mark recording method capable of forming an accurate bit width size.

[0011]

In order to achieve the above object, the present invention provides a method of drawing a fine pattern by irradiating a sample with an electron beam squeezed into a fine pattern. It is characterized in that the exposure amount is controlled. That is, the present invention can be applied to semiconductor devices as well as optical and magnetic disks. Further, the present invention is characterized in that, in the electron beam drawing method, the exposure amount of the electron beam is controlled by controlling a blanking characteristic. Further, the present invention is characterized in that, in the electron beam drawing method, a blanking function and an exposure amount control function are provided as the blanking characteristics.

Further, according to the present invention, a minutely focused electron beam is oscillated in a direction intersecting with the moving direction of the sample to control the amplitude and irradiate the sample to record in a spiral, concentric or linear array. The mark recording method is characterized in that, when a mark having information is drawn, the exposure amount of the electron beam to the mark is controlled.

Further, according to the present invention, in the mark in the mark recording method, the mark has length information in the tangential direction, width information in the radial direction or offset information from the center of the track in the radial direction. Characterize. In the mark recording method of the present invention, the exposure amount of the electron beam to the mark is controlled.
It is characterized in that it is performed by controlling the blanking characteristic. Further, the present invention is characterized in that the mark recording method has a blanking function and an exposure amount control function as the blanking characteristics. In the mark recording method of the present invention, the exposure amount control function is pulse width modulation control. Further, the present invention is characterized in that, in the mark recording method, the exposure amount control function is voltage control when an electron beam is ON.

Further, the present invention comprises an electron gun, a condenser lens for narrowing the electron beam emitted from the electron gun, and a blanking control means having a blanking electrode for controlling ON / OFF of irradiation of the electron beam to the sample. An electron optical system having a deflection electrode for deflecting the electron beam narrowed down by the condenser lens and an objective lens for irradiating the sample with a finely focused electron beam is provided, and the objective lens of the electron optical system is used for finely focusing the electron beam. The electron beam is applied to the sample by oscillating the electron beam by the deflection electrode in a direction crossing the moving direction of the sample to control the amplitude, and oscillating the electron beam at the amplitude controlled by the amplitude control means. An electron beam drawing apparatus, comprising: an exposure amount control means for controlling an exposure amount of an electron beam to the fine pattern when the fine pattern is drawn.

Further, the present invention is characterized in that, in the electron beam drawing apparatus, the exposure amount control means is provided in the blanking control means. Further, the present invention is characterized in that, in the electron beam drawing apparatus, the exposure amount control means is constituted by a pulse width modulation control means for a blanking electrode. Further, the present invention is characterized in that, in the electron beam drawing apparatus, the exposure amount control means is constituted by voltage control means for a blanking electrode when an electron beam is ON. Further, the present invention is characterized in that, in the electron beam drawing apparatus, the exposure amount control means is provided with an exposure amount control electrode. Further, according to the present invention, in the electron beam drawing apparatus, a blanking drive voltage input to a blanking electrode in the blanking control means is set to be larger than an exposure amount control drive signal in the exposure amount control means. Characterize.

Further, according to the present invention, in order to control the exposure amount as shown in FIG. 3 (d), (1) pulse width modulation method and (2)
Use the transient characteristics when cutting the beam during blanking. The method is described below. The pulse width modulation method (1) is a method of controlling the exposure amount by repeatedly generating pulses and controlling the duty at that time. That is, in (1), the blanking signal is corrected as shown in FIG. 4 to control the exposure amount. Figure 4
3A is the same as FIG. 3D, which is the exposure correction amount.
The rightmost bit has different exposure amount from the center to the right and left. When this is subjected to exposure control by pulse modulation including the function of a blanking signal, a signal waveform as shown in FIG. 4C is obtained. The duty is about 60% on the left side where the exposure amount is small, but on the right side, the pulse train is close to 100%. In this way, the exposure amount can be corrected by pulse width modulation. The method (2) is a method of controlling the blanking voltage when the beam is turned on by utilizing the electron beam blanking-blanking voltage characteristic. That is, (2) is the blanking voltage-electron beam blanking characteristic shown in FIG.
The required voltages V1 and V2 are obtained from (b)) (V1: the right part of the right mark in FIG. 4A, V2: the left part of the right mark) and controlled to become V1 and V2 when the beam is turned on. By doing so, the exposure amount is controlled.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an electron beam drawing method and apparatus and a mark recording method according to the present invention will be described with reference to the drawings.

In Japanese Patent Application No. 2000-195096, we proposed to easily realize high density recording by giving multilevel information to the width. That is, as the drawing target (mark recording target) according to the present invention, as shown in FIG. 3A, there is a mark or mark array having recording information arranged in a spiral shape, a concentric shape, or a linear shape. In addition, a pattern of a semiconductor element can be considered as a drawing target. In the above-mentioned mark or mark row, by recording length information in the tangential direction, width information in the radial direction, or offset information in the radial direction from the center of the track on the track, multi-valued information can be recorded at high density. Is possible.

The embodiments of the present invention will be specifically described below.

[First Embodiment] FIGS. 1 and 4 are views showing an electron beam drawing apparatus according to a first embodiment of the present invention, in which an exposure amount is controlled by electric pulse width control. . In FIG. 1, the electron optical system includes a Schottky emission type field emission electron gun 1, a condenser lens 2, an ion pump 9 for evacuating, a valve 3 for passing an electron beam, a blanking electrode 8, an aperture 28, a deflection coil 4, an ion pump. 9 and the objective lens 22. This optical system is connected to the sample chamber 5 and the vacuum exhaust system 7 to form a housing portion. The sample chamber 5 has a sample table that supports the sample 6 and is orthogonal to the sample table or has a rotation moving mechanism 13 that can rotate and move the recording mark in a concentric circle shape and a spiral shape. As a result, minute bits can be formed as concentric circles or spiral marks on the optical and magnetic recording media. At this time, the mechanical system has a position error of about 1 μm. This is feed-forward controlled by a deflection system to perform highly accurate mark row formation.

In order to ensure uniformity and high accuracy when forming the mark row, basically, the electron beam 10 obtained by the field emission from the electron gun chip 27 is narrowed by the condenser lens 2, Further, it is necessary to focus on the sample 6 with the objective lens 22 and to perform it without changing the beam diameter and the beam current of the beam spot of the nanometer order. Therefore, as described below, exposure amount control based on amplitude control by electron beam deflection and blanking control is required.

Next, a specific example of amplitude control by electron beam deflection will be described with reference to FIG. First, a case where an amplitude-modulated mark string is desired to be drawn will be described. Figure 3
(A) shows a signal of each part when it is desired to draw an amplitude-modulated mark string. In this mark row, M
P is the mark pitch, l is the length of one mark, and w is the width of one mark. Reference numeral 30 indicates the track center of recorded information arranged in a spiral shape, a concentric shape, or a linear shape. Reference numeral 31 indicates the rotation direction or movement direction of the drawing target. Further, FIG. 3B is a diagram showing a bit width control signal (electron beam deflection signal) 36 applied to the deflection electrode 35 when the mark row shown in FIG. 3A is drawn. This Figure 3
Based on the control of the deflection electrode 35 by the bit width control signal shown in (b), the electron beam 10 can vibrate in a direction substantially perpendicular to the length direction of the mark to form a mark having a desired width. .

That is, when it is attempted to draw the mark width as shown in FIG. 3A, the electron beam 10 is oscillated in a direction substantially perpendicular to the sample stage moving direction as shown in FIG. By controlling, the bit width can be controlled.

However, at this time, the sample 6 is placed on the linear moving table or the rotating body 13 which is moving at a constant speed, and the sample 6 is moving at a constant speed. Therefore, the exposure amount and the dose amount are not constant on the sample, as shown by the relative change in the exposure amount in FIG. Therefore, it is impossible to form an accurate mark width. This is because the exposure amount control function is not possessed electronically.

Therefore, the present invention is provided with a means for controlling the exposure amount of the electron beam, and the exposure amount is adjusted as shown by the control exposure amount (arbitrary unit) for obtaining a uniform exposure density in FIG. To control. Thus, in order to correct the exposure amount so that the constant exposure amount per unit area (constant dose amount: constant exposure density), the exposure amount can be controlled as shown in FIG. Will be needed. That is, the present invention is to electronically realize the function of controlling the exposure amount of the electron beam when it reaches the sample.

By the way, in the first embodiment, as shown in FIG.
In order to realize the exposure amount control as shown in (d), a pulse width modulation method was used as shown in FIG.

In the pulse modulation method, as shown in FIG. 4, pulses are repeatedly generated from the pulse generator 18 and the duty of the pulse at that time is controlled (pulse width control).
Is a method for controlling the exposure amount. The blanking signal 20 shown in FIG. 4B is corrected (pulse-modulated) as shown in FIG. 4C to control the exposure amount. Figure 4 (a)
3 is the same as FIG. 3D and is a relative exposure correction amount. The rightmost bit has different exposure amount from the center to the right and left.
When this is exposure-controlled by pulse width modulation including the function of the blanking signal 20, a signal waveform as shown in FIG. 4C is obtained.
The duty is about 60% on the left side where the exposure amount is small, but on the right side, the pulse train is close to 100%. By applying the pulse-width-modulated signal 41 formed by the blanking circuit 14 to the blanking electrode 8 in this way, the exposure amount can be corrected. The signal 41 at this time is formed by the blanking circuit 14 shown in the upper right of FIG. The control system 12 is a computer system 11
A blanking signal 20 and an exposure amount control signal 21 are input to the blanking circuit 14 based on the data output from the. The AND circuit 17 receives the input blanking signal 2
The AND of 0 and the signal (pulse train) input from the pulse generator 18 is taken and input to the flip-flop (FF) circuit 16. Further, the pulse train obtained from the AND circuit 17 is delayed by the delay circuit 19 and the FF circuit 16
Is input as a reset signal of. The delay time at this time is determined by the exposure amount control signal 21. In this way, the signal obtained from the FF circuit 16 is converted into an appropriate voltage by the drive circuit 15, and the pulse train signal 41 shown in FIG. 4C can be obtained. In this way, the bit width control signal (electron beam deflection signal) 3 shown in FIG.
6 is applied to the deflection coil 4 to control the mark width, and a blanking control signal (pulse width duty control signal) 41 for obtaining a uniform exposure density shown in FIG.
Is applied to the blanking electrode 8 to
With a uniform exposure amount (uniform exposure density) as shown in (a),
A mark (pattern) can be formed, and as a result, an accurate mark width can be formed at the nanometer level, and a minute recording mark or a semiconductor element pattern can be formed more accurately.

[Second Embodiment] The second embodiment differs from the first embodiment in the exposure amount control using the blanking characteristic as shown in FIG. FIG. 5A shows the optical path of the blanked electron beam 34. The center of the blanking electrode 8 is arranged so that the electron beam becomes a crossover point formed by the condenser lens 2. As a result, the spot position narrowed down on the sample 6 does not change in position even if the electron beam is swung by the blanking signal 33, and the electron beam 1
It is an optical system that changes only the strength of 0. When the electron optical system is designed in this way, the blanking voltage-electron beam blanking characteristic (beam ON / OFF characteristic) is as shown in FIG. 5B because part of the electron beam is blocked by the aperture 28. can get.

For example, when the exposure amount of the right-side mark in FIG. 4A is corrected, the required voltages V1 and V2 (V
The right part of the mark in FIG. 4 (a), V2: the left part of the mark in FIG. 4 (a) can be obtained. By controlling the blanking electrode 8 so that these voltages become V1 and V2 when the beam is turned on, the exposure amount can be controlled to a constant exposure density. As a result, similarly to the first embodiment, it is possible to realize the mark (pattern) formation with a uniform exposure amount (uniform exposure density) as shown in FIG.

[Third Embodiment] The third embodiment is different from the first and second embodiments in that, as shown in FIG. 6, two sets of blanking electrodes 8 and 26 are provided. Is to use. The first and second embodiments are executed by signals. However, since the blanking electrodes have different sensitivities and high speeds, the third embodiment is different from the blanking electrodes suitable for their respective functions. This enables more practical blanking and exposure amount control. Figure 6
FIG. 8 is a diagram showing a specific example applied to two sets of blanking electrodes 8 and 26. The blanking circuit 14 is provided with two channels 61 and 62, and one channel 61
Is provided with a blanking function, and the other channel 62 is provided with an exposure amount control function. One channel is control system 1
The drive circuit 24 based on the blanking signal 20 from 2 forms the signal 61 having the blanking function shown in FIG. The other channel is the control system 12
The exposure amount control signal 21 is converted into an analog signal by the DA converter 23 and is formed by the drive circuit 25 as the signal 62 having the exposure amount control function shown in FIG. 7B. Then, the respective signals 61 and 62 are input to the first blanking electrode 8 and the second blanking electrode 26 to realize the above function.

Using these two sets of blanking electrodes,
For the blanking function, the beam can be swung to a large extent to focus on cutting the beam completely, and a large cutoff sensitivity can be selected. On the other hand, the one having a small blocking sensitivity is suitable for the exposure amount control. Even if the sensitivities are compared in this way, it is preferable that they differ from each other, and it can be said that this method is close to practical use.

When this system is applied to the pulse modulation system of the first embodiment, the pulse frequency of the exposure amount control signal needs to be high and the capacitance of the second blanking electrode 26 is Need to be small. The second blanking electrode 26 has a smaller capacity when the cutoff sensitivity is reduced, and a cutoff rate of about 99% is sufficient, so that the drive voltage may be small. That is, it is very convenient for high-speed exposure control.

As described above, according to the embodiment of the present invention, a uniform exposure density is obtained by correcting the exposure amount corresponding to the change in the exposure amount that occurs when the recording mark width is controlled. Obtainable. This enables accurate mark width formation. The above specific examples have been shown as examples for application to optical and magnetic disks, but they are also within the scope of the present invention when applied to an electron beam drawing apparatus for semiconductors in which a moving table makes a step-and-repeat motion.

In the third embodiment, the example of pulse width modulation is not shown, but naturally pulse width modulation can also be used for exposure amount control. Further, it is desirable that the maximum value of the blanking voltage is larger than the maximum value of the exposure amount control voltage. This is because the blanking function needs to completely block the electron beam.

Furthermore, the proximity effect appears when drawing a minute pattern using an electron beam. Correcting this with the present invention is also within the scope of the present invention.

[0036]

According to the present invention, it is possible to obtain a uniform exposure density by correcting the exposure amount corresponding to the change in the exposure amount that occurs when the width of the recording mark is controlled. The mark width can be formed, and a finer recording mark or a semiconductor element pattern can be formed more accurately.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an electron beam drawing apparatus having an exposure amount control by pulse width control which is a first embodiment according to the present invention.

FIG. 2 is a diagram showing a conventional electron beam drawing apparatus having a blanking function.

FIG. 3 is a diagram showing a timing chart for performing mark width control by electron beam deflection according to the present invention.

FIG. 4 is a diagram showing a timing chart for uniformizing an exposure density by pulse width control, which is a feature of the first embodiment of the present invention.

FIG. 5 is a diagram illustrating a blanking signal with an exposure amount control function using a blanking characteristic that is a feature of the second embodiment of the present invention.

FIG. 6 is a diagram showing an electron beam drawing apparatus with exposure amount control having two sets of parallel plate electrodes or blanking electrodes, which is a feature of the third embodiment of the present invention.

7 is a diagram showing a specific example of a signal applied to each electrode of the device having two sets of blanking electrodes shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Schottky emission type field emission electron gun, 2 ... Condenser lens, 3 ... Valve, 4 ... Deflection coil, 5 ... Sample chamber, 6 ... Sample, 7 ... Vacuum exhaust system, 8 ... Blanking electrode, 9 ... Ion pump, 10 ... Electron beam, 11 ... Computer system, 12 ... Control system, 13 ... Orthogonal or rotational movement mechanism, 14 ... Blanking circuit, 15 ... Driving circuit, 16 ...
FF (flop flip) circuit, 17 ... AND circuit, 1
8 ... Pulse generator, 19 ... Delay circuit, 20 ... Blanking signal, 21 ... Exposure amount control signal, 22 ... Objective lens, 2
3 ... DA converter, 24 ... Drive circuit, 25 ... Drive circuit, 2
6 ... Second blanking electrode, 27 ... Electron gun chip, 2
8 ... Aperture, 30 ... Track center, 33 ... Blanking signal, 34 ... Blanked electron beam, 35
Deflection electrode, 36 Deflection signal.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tetsuya Nishida             1-280, Higashi Koikekubo, Kokubunji, Tokyo             Central Research Laboratory, Hitachi, Ltd. F-term (reference) 2H097 BB01 CA16 LA10 LA20                 5C033 GG03                 5C034 BB03 BB04                 5D121 BB26 BB38                 5F056 AA02 CB05 CB13 CB16 EA03

Claims (5)

[Claims] 1. A method of drawing a fine pattern by irradiating a sample with a finely focused electron beam, wherein the exposure amount of the electron beam for drawing the fine pattern is controlled. 2. A mark having recorded information arranged in a spiral shape, a concentric shape, or a linear shape by irradiating a sample by oscillating a minutely focused electron beam in a direction intersecting with the moving direction of the sample to control the amplitude and irradiating the sample. A mark recording method, wherein the exposure amount of the electron beam to the mark is controlled when the mark is drawn. 3. An electron gun, a condenser lens for narrowing the electron beam emitted from the electron gun, and ON / OFF of irradiation of the sample with the electron beam.
An electron optical system having a blanking control means having a blanking electrode for controlling OFF, a deflection electrode for deflecting the electron beam narrowed down by the condenser lens, and an objective lens for irradiating the sample with a minute electron beam. And an amplitude control means for controlling the amplitude by vibrating an electron beam minutely narrowed down by the objective lens of the electron optical system in the direction intersecting the moving direction of the sample by the deflection electrode, and controlled by the amplitude control means. And an exposure amount control means for controlling the exposure amount of the electron beam to the fine pattern when the fine pattern is drawn by irradiating the sample with the electron beam by vibrating with different amplitude. apparatus. 4. The exposure amount control means comprises pulse width modulation control means for the blanking electrode or voltage control means for the blanking electrode when the electron beam is ON. Electron beam writer. 5. An electron beam drawing apparatus according to claim 3, wherein said exposure amount control means is configured to have an exposure amount control electrode.