JP2004079334A - Electron beam device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electron beam device capable of arranging an electron beam path on the same axis as an electron beam. <P>SOLUTION: A first electron beam sensor 70 detecting the center of a mounting board 61 by directly detecting the electron beam from an electron beam source is fitted on one side of the mounting board 61 constituting a semiconductor electron beam detector 60, divided into four regions A1 to A4. A signal in accordance with an incident volume of the electron beam is outputted from each region A1 to A4. A center of the mounting board 61 is detected by moving the semiconductor electron beam detector 60 so that the output signals from the regions A1 to A4 become all equal to position the electron beam path 75 and the electron beam EB on the same axis. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electron beam device such as an electron microscope and an electron beam exposure device having a semiconductor electron beam detector for detecting an electron beam.
[0002]
[Prior art]
In an electron microscope or an electron beam exposure apparatus for transferring a fine pattern to a semiconductor element, a semiconductor electron beam detector is used as a detector for detecting an electron beam.
[0003]
FIG. 5 is a conceptual diagram of a conventional electron microscope.
[0004]
This electron microscope includes an electron beam source 110, a condenser lens system 120, an object lens system 130, and a stage 140.
[0005]
The electron beam source 110, the condenser lens system 120, the object lens system 130, and the stage 140 are housed in a housing 150 in a vacuum atmosphere.
[0006]
A semiconductor electron beam detector 160 is arranged between the object lens system 130 and the sample 105 placed on the stage 140.
[0007]
The electron beam emitted from the electron beam source 110 is converged by the condenser lens system 120 and the object lens system 130 and irradiates the sample 105. The electron beam reflected by the sample 105 is detected by the semiconductor electron beam detector 160.
[0008]
The semiconductor electron beam detector 160 includes an electron beam sensor 180 (see FIG. 6) fixed to a substrate (not shown), and is fixed to the object lens system 130 by, for example, a screw.
[0009]
Note that an electron beam exposure apparatus is different from an electron microscope in that an exposure amount and an electron dose are detected by detecting an amount of an electron beam reflected from a semiconductor wafer in which a sample 105 is a semiconductor wafer.
[0010]
FIG. 6 is a sectional view of a conventional electron beam sensor.
[0011]
The electron beam sensor 180 has the same configuration as a sensor that receives visible light, and is formed by a silicon process.
[0012]
The electron beam sensor 180 has a circular shape, and an electron beam passage 175 for passing an electron beam is provided at the center (the center of the circular substrate). The electron beam passage 175 is arranged coaxially with the electron beam.
[0013]
A P ⁺ type diffusion region and an N ⁺ type diffusion region are formed on the surface of the N ⁻ type semiconductor substrate constituting the electron beam sensor 180.
[0014]
A charge-up prevention film 176 and a silicon oxide film 177 are formed on the surface of the N ⁻ type semiconductor substrate on which the P ⁺ type diffusion region and the N ⁺ type diffusion region are formed. The charge-up prevention film 176 is formed around the electron beam path 175. The silicon oxide film 177 is formed outside the charge-up prevention film 176.
[0015]
Also, ^{P +} electrode 178 and the ^{N +} electrode 179 are respectively connected to the ^{P +} -type diffusion region and the ^{N +} -type diffusion region.
[0016]
[Problems to be solved by the invention]
By the way, the electron beam is conventionally accelerated at an acceleration voltage of about 30 to 40 keV. However, with the recent improvement in the performance of the electron beam source, it is necessary to accelerate the electron beam at an acceleration voltage of 100 keV or more to increase the energy of the electron beam. It is now possible.
[0017]
When the energy of the electron beam is increased, the resolution is improved in the electron microscope and the throughput is improved in the electron beam exposure apparatus. However, the deterioration of the electron beam sensor 180 for detecting the electron beam is accelerated. The container 160 has to be replaced.
[0018]
However, since a mechanism for detecting the center of the substrate of the semiconductor electron beam detector 160 is not provided in an electron microscope or the like, when the semiconductor electron beam detector 160 is replaced, the electron beam passage 175 is coaxial with the electron beam. There is a problem that it cannot be placed on top.
[0019]
The present invention has been made in view of such circumstances, and an object of the present invention is to provide an electron beam apparatus that can arrange an electron beam path coaxially with an electron beam.
[0020]
[Means for Solving the Problems]
In order to solve the above problem, the invention according to claim 1 includes an electron beam source, a condenser lens system and an object lens system arranged between the electron beam source and a sample mounted on a stage, In an electron beam device including a lens system and a semiconductor electron beam detector disposed between the sample, the semiconductor electron beam detector is provided on a mounting substrate and one surface of the mounting substrate, A first electron beam sensor for directly detecting an electron beam from the electron beam source to detect the center of the mounting substrate, and an electron beam provided on the other surface of the mounting substrate and reflected by the sample. And a second electron beam sensor for detecting.
[0021]
According to a second aspect of the present invention, in the electron beam apparatus according to the first aspect, a support mechanism for detachably supporting the semiconductor electron beam detector is provided in the object lens system, and accommodates at least the object lens system. An opening for taking the semiconductor electron beam detector in and out of the housing is provided.
[0022]
According to a third aspect of the present invention, in the electron beam apparatus according to the first or second aspect, a region for detecting the electron beam of the first electron beam sensor is divided, and an output signal from each region is used for the mounting. It is characterized in that the direction and amount of shift of the electron beam with respect to the center of the substrate are detected.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0024]
FIG. 1 is a conceptual diagram of an electron microscope according to one embodiment of the present invention.
[0025]
This electron microscope (electron beam device) includes an electron beam source 10, a condenser lens system 20, an object lens system 30, and a stage 40.
[0026]
The electron beam source 10, the condenser lens system 20, the object lens system 30, and the stage 40 are housed in a housing 50 in a vacuum atmosphere.
[0027]
A semiconductor electron beam detector 60 is disposed between the object lens system 30 and the sample 5 placed on the stage 40.
[0028]
The semiconductor electron beam detector 60 is moved in a horizontal direction along a rail 65 provided below the object lens system 30, and is fixed at a predetermined position by a fitting mechanism (not shown).
[0029]
The movement of the semiconductor electron beam detector 60 is performed using a feed-through 66 which is a linear movement mechanism in a vacuum. The rail 65, the fitting mechanism, and the feed-through 66 constitute the supporting mechanism of the second aspect.
[0030]
One end of the feedthrough 66 is screwed into the semiconductor electron beam detector 60 via an opening 32 provided in the housing 31 that houses the object lens system 30.
[0031]
The other end of the feedthrough 66 extends to the outside via a hole (not shown) formed in a wall surface 56 of a preliminary exhaust chamber 55 provided in the housing 50 of the electron microscope. The periphery of the hole is sealed so that a low pressure in the preliminary exhaust chamber 55 can be maintained.
[0032]
In the preliminary exhaust chamber 55, a housing 50 for the electron microscope and the preliminary exhaust chamber 55 are partitioned, and a blocking mechanism (not shown) for keeping the inside of the housing 50 in a vacuum atmosphere is provided. Further, a vacuum exhaust valve (not shown) is provided in the preliminary exhaust chamber 55, and the inside of the preliminary exhaust chamber 55 can be adjusted to a predetermined pressure.
[0033]
An operation procedure for replacing the semiconductor electron beam detector 60 of the electron microscope will be described below.
[0034]
First, the currently mounted semiconductor electron beam detector 60 is transferred to the preliminary exhaust chamber 55, and the preliminary electron exhaust chamber 55 is set to the atmosphere to remove the semiconductor electron beam detector 60.
[0035]
Next, the feedthrough 66 is screwed into the side surface of the newly mounted semiconductor electron beam detector 60. The inside of the preliminary exhaust chamber 55 is evacuated from the evacuation valve so that the degree of vacuum in the casing 50 is substantially equal to the degree of vacuum.
[0036]
Thereafter, the feed-through 66 is pushed in while the vacuum atmosphere is maintained in the preliminary exhaust chamber 55, and the semiconductor electron beam detector 60 is transferred into the housing 31 accommodating the object lens system 30.
[0037]
Finally, the feedthrough 66 is detached from the semiconductor electron beam detector 60 and returned to the original position, and the replacement of the semiconductor electron beam detector 60 is completed.
[0038]
Thereafter, the electron beam path 75 (see FIG. 2) and the electron beam are positioned coaxially.
[0039]
FIG. 2A is a perspective view of a semiconductor electron beam detector, and FIG. 2B is a cross-sectional view taken along line 2b-2b in FIG. 2A.
[0040]
The semiconductor electron beam detector 60 is provided on a mounting substrate 61 and on one surface of the mounting substrate 61, and directly detects an electron beam from the electron beam source 10 to detect the center of the mounting substrate 61. It has one electron beam sensor 70 and a second electron beam sensor 80 provided on the other surface of the mounting substrate 61 and detecting an electron beam reflected by the sample 5.
[0041]
The first electron beam sensor 70 and the second electron beam sensor 80 are circular and each has a radius of 18 mm.
[0042]
As the second electron beam sensor 80, a conventional electron beam sensor (see FIG. 6) can be used. Note that the number of regions for detecting the reflected electron beam is not limited to one, and a plurality of regions may be provided as in FIG.
[0043]
Although not shown, the second electron beam sensor 80 is connected to an electrode formed on the outer peripheral edge of the mounting substrate via a thin metal wire.
[0044]
The mounting substrate 61 is formed of, for example, a ceramic substrate having durability against electron beams. The mounting substrate 61 is a disk having a radius and a thickness of 25 mm and 1 mm, respectively.
[0045]
An electron beam passage 75 for passing an electron beam is provided at the center of the first electron beam sensor 70, the mounting substrate 61, and the second electron beam sensor 80. The radius of the electron beam path 75 is 7 mm.
[0046]
FIG. 3A is a plan view of one surface of the mounting board, and FIG. 3B is a cross-sectional view taken along line 3b-3b. In FIG. 3B, the illustration of the second electron beam sensor 80 provided on the other surface of the mounting substrate 61 is omitted.
[0047]
The first electron beam sensor 70 has the same configuration as a sensor that receives visible light, and is formed by a silicon process.
[0048]
The first electron beam sensor 70 formed on the outer periphery of the electron beam passage 75 is divided into four regions A1 to A4 for detecting an electron beam.
[0049]
A P ⁺ -type diffusion region and an N ⁺ -type diffusion region are formed on the surface of an N ⁻ -type semiconductor substrate constituting an electron beam sensor.
[0050]
A charge-up prevention film 76 and a silicon oxide film 77 are formed on the surface of the N ⁻ type semiconductor substrate on which the P ⁺ type diffusion region and the N ⁺ type diffusion region are formed. The charge-up prevention film 76 is formed around the electron beam path 75 (four regions A1 to A4). The silicon oxide film 77 is formed outside the charge-up prevention film 76.
[0051]
An anode electrode (P ⁺ electrode) 78 and a cathode electrode (N ⁺ electrode) 79 are connected to the P ⁺ type diffusion region and the N ⁺ type diffusion region, respectively.
[0052]
The anode electrode 78 and the cathode electrode 79 are connected to electrodes 62 and 63 formed on the outer peripheral edge of the mounting substrate 61 via thin metal wires 73 and 74, respectively. Signals are input to and output from the first electron beam sensor 70 via the thin metal wires 73 and 74.
[0053]
For example, when an electron beam enters the region A1, a pair of a hole and an electron is formed according to the incident amount of the electron beam (one hole-electron pair is formed theoretically at 3.6 eV). ).
[0054]
Therefore, when the electron beam accelerated by the voltage of 100 keV is incident on the region A1, 27 × 10 ³ times the electric charge which is theoretically incident is output as a signal.
[0055]
Similarly, the electron beam enters the other regions A2 to A4, and a signal corresponding to the incident amount of the electron beam is output from each of the regions A1 to A4.
[0056]
Therefore, the shift direction and the shift amount of the electron beam with respect to the center of the mounting substrate 61 can be detected by the signals output from the regions A1 to A4.
[0057]
As a result, the center of the mounting substrate 61 can be detected.
[0058]
FIG. 4 is a view for explaining an example of the work of aligning the electron beam path with the electron beam.
[0059]
When the semiconductor electron beam detector 60 is replaced, since the electron beam path 75 is not located coaxially with the electron beam EB, the position of the electron beam path 75 and the electron beam EB is determined using the first electron beam sensor 70. Perform matching work.
[0060]
For example, as shown in FIG. 4, when the electron beam EB is displaced to the right with respect to the electron beam path 75, the output signal from the right region for detecting the electron beam EB increases.
[0061]
Therefore, the semiconductor electron beam detector 60 is moved, for example, to the left as indicated by a white arrow so that the output signals from all the areas A1 to A4 become equal.
[0062]
When the electron beam EB coincides with the center of the mounting substrate 61 (when the displacement of the electron beam is eliminated), the output signals from the regions A1 to A4 are all equal, so that the electron beam passage 75 and the electron beam EB are coaxial. You can see that it was located above.
[0063]
After the alignment, the electron beam reflected by the sample 5 is detected by the second electron beam sensor 80 provided on the sample 5 side.
[0064]
According to this embodiment, when the semiconductor electron beam detector 60 is replaced, the center of the mounting substrate 61 can be detected based on signals output from the areas A1 to A4. Can be placed on top.
[0065]
Further, since the semiconductor electron beam detector 60 supported by the rail 65 can be replaced from outside the housing 50 using the feedthrough 66, the semiconductor electron beam detector 60 can be replaced very easily. .
[0066]
Further, when the alignment is performed, damage of the sample 5 can be prevented.
[0067]
In the above embodiment, the first electron beam sensor 70 has a circular shape, but may have a rectangular shape, for example.
[0068]
In the above embodiment, the first electron beam sensor 70 is divided into four parts, but may be divided into four or more parts, for example, eight parts or sixteen parts. The multi-division makes it possible to detect the center of the mounting substrate 61 with high accuracy.
[0069]
【The invention's effect】
As described above, according to the electron beam apparatus of the present invention, the electron beam path can be arranged coaxially with the electron beam.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram of an electron microscope according to an embodiment of the present invention.
FIG. 2A is a perspective view of a semiconductor electron beam detector, and FIG. 2B is a cross-sectional view taken along line 2b-2b in FIG. 2A.
FIG. 3A is a plan view of one surface of a mounting substrate, and FIG. 3B is a cross-sectional view taken along line 3b-3b.
FIG. 4 is a diagram illustrating an example of a work of aligning an electron beam path and an electron beam.
FIG. 5 is a conceptual diagram of an electron microscope.
FIG. 6 is a sectional view of a conventional electron beam sensor.
[Explanation of symbols]
5 Sample 10 Electron beam source 20 Condenser lens system 30 Object lens system 32 Opening 40 Stage 60 Semiconductor electron beam detector 61 Mounting board 65 Rail 66 Feedthrough 70 First electron beam sensor 80 Second electron beam sensors A1 to A4 Area for detecting electron beam

Claims (3)

An electron beam source, a condenser lens system and an object lens system arranged between the electron beam source and a sample mounted on a stage, and a semiconductor electron system arranged between the object lens system and the sample. An electron beam device comprising: a line detector;
The semiconductor electron beam detector,
A mounting substrate,
A first electron beam sensor provided on one surface of the mounting substrate and directly detecting an electron beam from the electron beam source to detect the center of the mounting substrate;
An electron beam device, comprising: a second electron beam sensor provided on the other surface of the mounting substrate and detecting an electron beam reflected by the sample. A support mechanism for detachably supporting the semiconductor electron beam detector is provided in the object lens system,
2. The electron beam apparatus according to claim 1, wherein an opening for taking in and out the semiconductor electron beam detector is provided at least in a housing accommodating the object lens system. An area for detecting the electron beam of the first electron beam sensor is divided, and a shift direction and a shift amount of the electron beam with respect to a center of the mounting substrate are detected based on output signals from the respective areas. The electron beam device according to claim 1.

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