JP2005149806A - Electron beam irradiation device and electron beam irradiation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure an electron beam spot with an electron beam spot detector in a fixed state. <P>SOLUTION: The electron beam irradiation device has an electron beam axis controlling unit 34 which comprises an electron (EB) gun 1; an intermediate lens system 9; an aperture 16 for blanking made of a thin material; an electrostatic deflection electrode 14 for blanking rejecting the electron beam from the position excluding the hole by blanking the position of the electron beam passing through the hole by moving it in a lateral direction and changing its passage by a physical action; a CCD 12 detecting physical reaction when blanking and irradiating the electron beam on the aperture 16 for blanking; and a two-dimensional display device 30 making the detected signal measurable by two-dimensionally visualizing the signal. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention provides an electron beam that detects an electron beam center position, irradiation intensity (including intensity distribution and size), and the like in an apparatus that carries an electron beam accelerator and that performs exposure drawing or observation / measurement using the irradiated electron beam. The present invention relates to a detector and a detection method.

  2. Description of the Related Art In recent years, for example, a wave of higher density of products represented by semiconductor elements or large capacity recording media exceeding 10 Gbytes has increased the demand for drawing apparatuses or measuring apparatuses using electron beams. In using these electron beam apparatuses, in order to perform high-precision exposure or accurate measurement, an optical axis adjustment (beam alignment) work is required in advance.

  Conventionally, the optical axis adjustment work of the electron beam is different from the optical axis adjustment work of the laser beam, and it is very difficult to monitor information such as the position of the beam and the beam diameter in the middle of the optical axis system. I can't give feedback. Therefore, the procedure for adjusting the optical axis of the electron beam is to adjust the optical system (hereinafter referred to as the lens system) so as to gradually approach the just optical axis (hereinafter referred to as the optical axis center). It will take the technique of repeating the act of adjusting from the bottom to the bottom. Therefore, the optical axis adjustment of the electron beam is generally time consuming, and an optical axis adjustment procedure that can be efficiently performed in a short time has been desired.

  As one means for improving the efficiency of the optical axis adjustment of the electron beam, the position and shape of the beam spot in the middle of the optical axis of the electron beam are detected and measured, and the value is obtained until reaching the beam spot position. Feedback to the adjustment of the lens system is raised. That is, for example, if the parameters can be determined in a closed lens system that is divided to some extent at the front and rear stages of the lens system as is done by adjusting the optical axis of the laser beam, it is efficient even in the case of an electron beam. Optical axis adjustment can be realized. For these reasons, a means for detecting a beam spot in the middle of the optical axis of the electron beam is required.

Patent Document 1 includes an electron beam generator, an electron beam irradiation unit, an optical system, and a light detection unit so that the electron beam irradiation can be performed in the best state. In this configuration, a material containing a material that emits light by electron beam excitation is introduced. Light generated by electron beam irradiation is introduced into the light detection unit through an optical system, and the irradiation state of the electron beam is detected. An electron beam irradiation method for controlling the electron beam irradiation so as to be irradiated in an optimum state is disclosed.
JP 2002-222748 A

  By the way, when a beam spot in the middle of the optical axis system of an electron beam is detected, it is a well-known means for detecting, for example, an electron beam is applied to a ceramic plate such as alumina, and the light emission state is determined by a CCD (charge coupled). device) or a method of measuring a current value that is directly applied to a divided electron detection sensor.

However, in order to realize these methods, an action such as inserting the above-mentioned ceramic plate or a jig with a sensor attached on the optical axis of the electron beam is necessary. In the case of an action including such a physical movement operation, the reproducibility is important, and a problem arises that accurate measurement cannot be performed due to a slight change in position, angle, and the like.
Therefore, it is desirable that the electron beam detector is fixed as much as possible.

  Further, Patent Document 1 introduces light reflected by an electron beam irradiation unit into an optical detection unit through an optical system, and detects the irradiation state of the electron beam. As in the present invention, the electron beam blanking device in the electron beam exposure apparatus is provided with a beam detection means, so that the center position and irradiation intensity of the directly irradiated electron beam are provided. This is different from that for detecting an accurate beam alignment.

  The present invention has been devised in view of the above points, and an object of the present invention is to provide a detection method / detector capable of measuring the state of an electron beam spot in a state where an electron beam spot detection device is fixed. And to realize an electron beam apparatus.

  In order to solve the above problems and achieve the object of the present invention, the present invention is narrowed down by an electron beam generating means for generating an electron beam, an electron beam narrowing means for narrowing the beam diameter of the electron beam, and an electron beam narrowing means. A thin plate-shaped opening means made of a material that has a very small hole through which an electron beam spot with a different beam diameter passes and that physically reacts upon irradiation of the electron beam, and an electron that passes through the hole of the plate-shaped opening means Blanking means for causing the electron beam spot to be repelled from a position other than the hole by moving the position of the beam spot in a horizontal direction with respect to the plate-like hole opening means by a physical action and changing the passage path so as to blank. Signal generating means for generating a signal for driving the ranking means, and physical when the plate-shaped aperture means is irradiated with an electron beam blanking The electron beam optical axis adjusting mechanism with respect to the electron beam generating means includes a detecting means for detecting a response and a measuring means for visualizing and measuring a signal based on the detected physical reaction in two dimensions, and blanking the electron beam. The electron beam irradiation apparatus measures the position, spot diameter and intensity of the electron beam by detecting the physical reaction state of the beam spot irradiated to the plate-shaped aperture means.

  The present invention also provides an electron beam generating step for generating an electron beam by the electron beam generating means, an electron beam narrowing step for narrowing the beam diameter of the electron beam by the electron beam narrowing means, and a beam diameter narrowed by the electron beam narrowing means. Blanking based on the drive signal from the signal generating means using a thin plate-like opening means made of a material that has a very small hole that allows the electron beam spot to pass through and that physically reacts when irradiated with the electron beam. The position of the electron beam spot passing through the hole of the plate-like opening means is moved by the physical action in the horizontal direction with respect to the plate-like opening means and the passage route is changed so that the electron is emitted from a position other than the hole. A blanking step for repelling the beam spot, and a blanking step for detecting the electron beam on the plate-like aperture means. An electron beam for the electron beam generating means, a detection step for detecting a physical reaction when the irradiation is performed, and a measurement step for visualizing and measuring a signal due to the physical reaction detected by the measurement means in two dimensions. An electron that measures the position, spot diameter, and intensity of the electron beam by detecting the physical reaction state of the beam spot irradiated to the plate-shaped aperture means by blanking the electron beam. This is an electron beam irradiation method in a beam irradiation apparatus.

  According to the present invention, the diameter of the electron beam is narrowed down, and a very small hole through which the electron beam spot narrowed down by the narrowing down of the beam diameter is opened, and is made of a material that emits light when irradiated with the electron beam. The position of the electron beam spot that passes through the hole of the thin plate-shaped aperture means is moved horizontally based on the drive signal and the passing path is changed to repel the beam spot from the hole position, thereby blanking the electron beam. The detected light emission is detected in two dimensions and can be measured. Thereby, the position, spot diameter, intensity, etc. of the electron beam can be measured by blanking the electron beam and detecting the light emission state of the beam spot irradiated to the plate-shaped aperture means. A more efficient optical axis adjustment mechanism can be realized by using.

  Further, according to the present invention, it is possible to detect and measure the irradiation position of the electron beam during the exposure, which has been conventionally difficult with an electron beam exposure apparatus, for example.

  As described above, according to the present invention, it is possible to detect the beam position, beam diameter, and beam intensity in the middle of the optical axis of the electron beam without physically blocking the optical axis, and there is a concern that it will be difficult and time consuming in the past. The optical axis adjustment of the existing electron beam apparatus can be performed by a simpler and more efficient method. In addition, it is possible to construct a system capable of detecting variations in the beam position and beam diameter in the middle of the optical axis system, which is conventionally difficult to detect during operation of the electron beam apparatus.

Hereinafter, the configuration of a system for carrying out the present invention will be described with reference to the drawings. FIG. 1 shows the configuration of an electron beam irradiation apparatus according to an embodiment of the present invention.
The electron beam emitted from the electron (EB) gun 1 is adjusted by first adjusting the tilt of the EB gun 1 and adjusting the alignment coil so that a portion of the electron beam irradiated from the EB gun 1 having a high current density is ext. The aperture is narrowed down by the aperture 35 and passed as vertically as possible to the lower lens system. The electron beam that has passed through the Ext stop 35 is adjusted in the amount of irradiation current by the condenser lens system 3, adjusted in the stop and the like by the intermediate lens system 9, and passed through the blanking mechanism system 13. Thereafter, the electron beam enters the objective lens system 17 and adjustment is performed on the substrate 22 to be exposed or observed. Secondary electrons or reflected electrons generated by the electron beam applied to the substrate 22 are detected by the upper electron detector (Upper-SED) 31 or the reflected electron detectors (PNJ) 24, 25 of the display processing system 23, The signal is amplified by the preamplifier circuit 24, the intermediate amplifier circuit 17 and the main amplifier circuit 28, subjected to the two-dimensional visualization processing by the two-dimensional visualization processing unit 29, and then visualized by the two-dimensional display device 30 and the focus adjustment image. And so on.

FIG. 2 is a partially enlarged example of the blanking mechanism in the blanking mechanism system of FIG.
The electron beam adjusted by the intermediate lens system 9 is blanked when an input signal to the blanking electrostatic deflection electrode 14 (hereinafter referred to as a blanking signal) is not applied (blanking OFF). The electron beam passes through the ranking aperture 16 as shown in the figure. As shown in this example, the blanking electrostatic deflection electrode 14 does not have to be a pair electrode. When a blanking signal is input from the blanking signal generator 44 to the blanking electrostatic deflection electrode 14, the optical path of the electron beam changes as indicated by the electrostatic deflection direction 43, and the hole of the blanking aperture 16 is changed. Therefore, the blanking aperture itself is irradiated with the electron beam. Since the blanking aperture 16 irradiated with the electron beam is composed of an electron beam emitter, the blanking aperture 16 emits light as indicated by 41, and the state of the emitted beam spot can be monitored by the CCD 12 provided at the top. I can do it. The signal monitored by the CCD 12 enters the amplifier circuit, is subjected to signal amplification processing, and is then input to the two-dimensional visualization processing unit 29. The signal input to the two-dimensional visualization unit 29 generates a signal such as a video signal and is visualized by the two-dimensional display device 30.

  The final object of the present invention is to enable monitoring of the electron beam spot state (beam position, spot diameter, intensity, etc.) in the middle of the electron beam optical axis in order to perform efficient electron beam optical axis adjustment. This is to feed back to the adjustment parameters of the lens system at a higher level. The present invention is characterized in that a blanking mechanism used in an electron beam apparatus is used and a mechanism for monitoring the state of the electron beam in the middle of the above-described electron beam optical axis is provided. Hereinafter, the principle for achieving the present invention will be specifically described with reference to the drawings.

  The blanking mechanism used in an electron beam exposure apparatus or the like is a function for not irradiating an electron beam to a portion where the electron beam is not desired to be exposed. The blanking aperture is preferably a mechanism that allows 100% of the electron beam to pass when blanking is OFF (beam exposure), and blocks 100% of the electron beam at high speed when blanking is ON (beam non-exposure). Therefore, as shown in FIG. 2, the blanking mechanism is such that the hole of the blanking aperture 16 is made to pass through the crossing point 42 of the electron beam focused by the lens system, and the hole diameter of the blanking aperture is made as small as possible. A means for moving the electron beam axis by the electrode is required. The present invention utilizes the characteristics of the blanking mechanism described above.

  First, blanking is turned on / off at a high speed by the blanking electrostatic deflection electrode 14 or the like. This is performed by an electric signal, and the beam is deflected with extremely high accuracy with respect to deflection of a constant voltage. If the blanking aperture 16 is fixed, the electron beam spot is deflected to the same position. Using this characteristic, if the blanking aperture is made of a material that emits light using an electron beam such as alumina, and the blanking aperture is monitored by the CCD 12 equipped on the top when blanking, it acts as a position detector. To do. For example, the blanking mechanism is designed with very small values such as a blanking aperture diameter of 10 to 50 μm and a blanking amount of 30 to 100 μm. Therefore, it is sufficient for the CCD 12 to have a 1 mm diameter near the electron beam passage hole. It is possible to monitor only by tilting it only a few degrees so as to be opposed to the light emitting direction indicated by 41, which is installed almost directly above the hole where even the optical axis portion through which the electron beam passes is not blocked. In addition, for example, macro / micro positioning can be performed by changing the field of view by electrical processing.

  Ideally, when the electron beam passes through the hole of the blanking aperture, the cross point 42 passes through the middle of the blanking aperture 16 in the height direction (horizontal to the axis of the electron beam). As shown in FIG. 2, the blanking operation does not move in the height direction and occurs only in the horizontal direction (direction perpendicular to the electron beam axis). If this characteristic is used, the case where the beam spot diameter at the time of blanking is the smallest and the light can be condensed can be regarded as a just adjustment point for the blanking aperture 16. In other words, the light emitting point diameter of the blanking aperture 16 detected by the CCD 12 may be adjusted to be the smallest.

  As described above, the cross point 42 is removed either vertically or vertically to turn on blanking, whereby the light emission of the beam spot spread on the blanking aperture 16 is detected by the CCD 12. The distribution of the light emission intensity (beam intensity) at this time is measured to measure the beam bias. By adjusting this distribution to be a Gaussian distribution that is symmetrical in the vertical and horizontal directions, an optical axis with less aberration can be obtained.

  Adjustment is simplified by making the parameters of the closed system adjustable while feeding back the detection signal of the CCD 12 above the blanking aperture 16 to the axis alignment coil 2 via the optical axis adjustment mechanism 34. The optical axis can be adjusted in a short time.

  For example, as described in FIG. 3 and subsequent figures, if a means using the above-described blanking mechanism is used, a detection signal (data) is output from the CCD 12 by a blanking signal from the blanking signal generator 44 even during electron beam exposure. ) Is taken out and information is processed, information on the optical axis position shift and diameter change can be obtained even during the exposure operation, and the fluctuation of the optical axis adjustment system above the blanking aperture 16 is known. Can be adjusted.

As shown in FIG. 3, two types of blanking apertures 16 of 10 μm and 30 μm are prepared for a passing beam diameter 51 of 6 μm. As shown in FIG. 3, the beam diameter 51 passing through the blanking aperture 16 is 6 μm, and when blanking is “OFF” (beam “ON”), the electron beam passes through the center of the blanking aperture 16. To do.

  The blanking signal generator 44 is supplied with a blanking input signal having a rising / falling characteristic of 5 to 10 nsec and a blanking input signal of 50 MHz with a cycle of 20 nsec as shown in FIG. 44, the blanking signal output from the blanking signal generator 44 has a waveform with a rising / falling characteristic of 5 nsec as shown in FIG.

  When blanking is “ON”, it is confirmed that the electron beam is blanked on the blanking aperture 16 by a distance of about 30 μm. When the blanking “ON” state is changed to the blanking “OFF” state, the distance from the outermost circumference of the passing beam diameter to the edge of the blanking aperture 16 is when the diameter of the blanking aperture is 10 μm. Since it is 22 μm, the time from when the blanking signal rises to when the electron beam actually starts to be radiated onto the blanking aperture 16 (irradiation beam rise start) is expressed by the following equation (1).

(Equation 1)
22 μm × (5 nsec / 30 μm) = 3.67 nsec

  Further, after the outermost periphery of the passing beam reaches the edge of the blanking aperture 16, the time for the beam to completely appear in the aperture (irradiation beam rising) is expressed by the following equation (2).

(Equation 2)
6μm × (5nsec / 30μm) = 1nsec

  Considering these times, the signal waveform of the irradiated electron beam is as shown in FIG. When the duty (duty) of the signal is evaluated with respect to the irradiation beam (consideration by considering the signal level center as a “Slash”), if the blanking aperture 16 is changed from 10 μm to 30 μm, the beam “ON” time is This is the difference shown in equation (3).

(Equation 3)
10nsec-6.16nsec = 3.84nsec
The signal waveform of the electron beam when the blanking aperture 16 is 30 μm is as shown in FIG.

  The present invention can be used for a mechanism for monitoring the state of an electron beam in the middle of an electron beam optical axis by using a blanking mechanism used in an electron beam exposure apparatus.

It is a block diagram which shows the structure of the electron beam irradiation apparatus by embodiment of this invention. It is a figure which shows the structural example of a blanking mechanism. It is a figure which shows the beam diameter which passes the aperture for blanking. It is a figure which shows the blanking input signal waveform of 50 MHz input into the blanking signal generator 44. It is a figure which shows the blanking signal waveform output from the blanking signal generator 44. It is a figure which shows the signal waveform of the electron beam irradiated when the aperture 16 for blanking is 10 micrometers. It is a figure which shows the signal waveform of the electron beam irradiated when the aperture 16 for blanking is 30 micrometers.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electron (EB) gun, 2 ... Axis alignment coil, 3 ... Condenser lens system, 9 ... Intermediate lens system, 12 ... CCD, 13 ... Blanking mechanism system, 14 ... Electrostatic deflection electrode for blanking, 16 ... Blank Aperture for ranking, 17 ... objective lens system, 23 ... display processing system, 30 ... two-dimensional display device, 34 ... optical axis adjusting mechanism, 41 ... light emission, 42 ... cross point, 43 ... electrostatic deflection direction, 44 ... blanking Signal generator, 45 ... Image

Claims (8)

An electron beam generating means for generating an electron beam;
An electron beam stop means for reducing the beam diameter of the electron beam;
A thin plate-shaped aperture means made of a material that has very small holes that allow the electron beam spot with the beam diameter narrowed down by the electron beam narrowing means to pass therethrough and that physically reacts when irradiated with the electron beam,
The position of the electron beam spot passing through the hole of the plate-like opening means is moved horizontally with respect to the plate-like opening means by a physical action, and the passage is changed so that the electron beam is blanked by changing the passage route. Blanking means to repel the beam spot;
Signal generating means for generating a signal for driving the blanking means;
Detecting means for detecting a physical reaction when the plate-shaped opening means is irradiated with an electron beam blanking; and
A measuring means for visualizing and measuring a signal due to the detected physical reaction in two dimensions;
Is provided in the electron beam optical axis adjusting mechanism for the electron beam generating means, and the electron beam is blanked to detect the physical reaction state of the beam spot irradiated to the plate-like aperture means, thereby Electron beam irradiation device that measures position, spot diameter and intensity. The electron beam irradiation apparatus according to claim 1,
The plate-shaped aperture means is composed of a material that emits light when irradiated with an electron beam. The electron beam irradiation apparatus according to claim 1,
An electron beam irradiation apparatus characterized in that optical axis adjustment in an electron beam is enabled by feeding back information on the electron beam spot to the optical axis adjustment mechanism. The electron beam irradiation apparatus according to claim 1,
An electron beam irradiation apparatus for measuring an electron beam during irradiation of an electron beam to the irradiated object by the electron beam generating means or during measurement of the measured object. An electron beam generating step of generating an electron beam by an electron beam generating means;
An electron beam stop step for narrowing the beam diameter of the electron beam by an electron beam stop means;
Using a thin plate-shaped aperture means made of a material that has a very small hole through which the electron beam spot with the beam diameter narrowed down by the electron beam narrowing means passes and that physically reacts by irradiation of the electron beam, Based on the driving signal from the signal generating means, the position of the electron beam spot passing through the hole of the plate-like aperture means is moved by the physical action in the horizontal direction with respect to the plate-like aperture means by the blanking means. A blanking step that causes blanking by changing and repels the electron beam spot from a position other than the hole,
A detection step of detecting a physical reaction when the plate-shaped aperture means is blanked and irradiated with an electron beam by the detection means;
A measurement step for visualizing and measuring a signal based on the physical reaction detected by the measurement means in two dimensions;
Is provided in the electron beam optical axis adjusting mechanism for the electron beam generating means, and the electron beam is blanked to detect the physical reaction state of the beam spot irradiated to the plate-like aperture means, thereby An electron beam irradiation method in an electron beam irradiation apparatus for measuring position, spot diameter and intensity. The electron beam irradiation method according to claim 5.
The electron beam irradiation method, wherein the plate-like opening means is made of a material that emits light when irradiated with an electron beam. The electron beam irradiation method according to claim 5.
An electron beam irradiation method comprising: an optical axis adjustment step that enables optical axis adjustment in an electron beam by feeding back information on the electron beam spot to the optical axis adjustment mechanism. The electron beam irradiation method according to claim 5.
The measuring step is an electron beam irradiation method in which an electron beam is measured during the electron beam irradiation to the irradiated object by the electron beam generating means or during the measurement of the measured object.

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