JPH0661126A - Electron beams device and orifice forming method - Google Patents

Abstract

PURPOSE:To enable the electron beams to be stably emitted while constantly substaining electron emitters at high vacuum degree in relation to the electron beam device capable of performing the steps such as exposure, lithography, inspection, etc., using electron beams. CONSTITUTION:The first orifice plate 54a wherein an orifice 63a is formed is provided in the paths of electron beams 62 beneath at electron emitter 56. This orifice perforated by the electron beams 62 in the same diameter as that of the electron beams 62 is to be formed in the specific number in the aligned state with the electron beams 62.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam apparatus for performing exposure, drawing, inspection, etc. using an electron beam.

In recent years, as an electron beam apparatus, development of a multi-electron beam type apparatus in which a large number of electron beams are arranged and processed in parallel in accordance with an increase in the amount of information to be inspected and the speed of a pattern to be drawn is being advanced. ing.

For that purpose, it is necessary to perform stable electron beam emission, a large number of orifices for electron beam emission are formed, and it is necessary to keep the electron emitter for beam emission always in a high vacuum.

[0004]

2. Description of the Related Art Conventionally, the inspection technology for semiconductor devices is
With the miniaturization of circuit patterns, electron beams have been used for detecting minute defects. In this case, in the sequential operation of a single electron beam against the rapid increase in the amount of information to be inspected, it takes time to transmit the image information to the signal processing system because signals are detected one by one in time series, and The inspection takes a long time. For this reason, a multi-electron beam type electron beam apparatus has been proposed in which a large number of electron beams are arranged and signal acquisition and signal processing are carried out in parallel.

Further, in the case of drawing by the multi-electron beam method, it is possible to perform drawing rapidly by irradiating a large amount of pattern data of a large amount at the same time, and it is possible to improve the throughput.

FIG. 7 shows a block diagram of a conventional multi-beam type electron beam apparatus.

The electron beam apparatus 11 shown in FIG. 7A is composed of an electron beam generating section 12, a sample section 13, a signal processing section 14, and a power supply 15. The electron beam generator 12 includes a plurality of electron emitters, an electron optical unit 21 that focuses and deflects an electron beam emitted from the electron emitters, and a detector 22 that detects secondary electrons (or reflected electrons). Focusing on the electron beam (described in FIG. 7B),
It has a fine adjustment circuit 23 for adjusting the deflection. in this case,
The detection signal from the detection unit 22 is sent to the signal processing unit 14.

Further, a plurality of electron beams from the electron optical section 21 irradiate the sample in the sample chamber 13.

Here, the electron optical section 21 and the detection section 22
As shown in FIG. 7B, the two-dimensionally arrayed micro cold cathodes (micro emitter arrays) serve as electron emitters 31, and the electron beams emitted from the electron emitters 31 are caused by the electrostatic lens focusing electrodes 32. It is focused, deflected by the deflection electrode 33, and scanned on the sample surface (34). Then, the detection unit 22 detects secondary electrons or reflected electrons from the sample surface.

By the way, the micro cold cathode used as the electron emitter 31 operates as a field emission type electron gun, and unlike the hot cathode type, a high-density space charge cannot be expected, and adsorbed atoms or molecules on the cathode surface are not expected. Has a drawback that the emission current is unstable due to a delicate change in the work function due to, a change in the surface shape due to the impact of ions ionized in the vicinity of the cathode on the cathode, and the like. Therefore, a normal field emission electron gun has a high vacuum (1
It is held at 0 ^-9 to 10 ^-10 Torr).

Usually, the vacuum degree of the sample chamber of a scanning electron microscope or an electron beam drawing apparatus is on the order of 10 ^-6 Torr, and a differential evacuation system is configured to maintain a high vacuum degree of the electron gun chamber. .

FIG. 8 shows a diagram for explaining a conventional differential pumping system.

FIG. 8 shows the case where a single electron beam is emitted, and the same principle applies to multiple beams.
In FIG. 8, the electron gun chamber 41 and the sample chamber 42 are communicated with each other, the electron gun chamber 41 is in the vacuum state by the ion pump 43, and the sample chamber 42 is in the vacuum state by the turbo pump 44.

The electron beam emitted from the electron emitter 45 of the electron gun chamber 41 has an anode hole 46a, a lens 47a, a condenser diaphragm hole 46b, and a lens 47.
It is guided to the sample chamber 42 through b, the aperture 46c of the objective diaphragm, and the deflector 47c. That is, the beam passage (47
a) -47c) and the holes (46a-46c) form exhaust conductances of "conduit" and "orifice" to form a differential exhaust system, and thus the electron gun chamber 4
1, the electron gun chamber 41
The high vacuum inside can be maintained.

[0015]

However, in the multi-electron beam type electron beam apparatus 11 as shown in FIG.
Even if the electrostatic lens focusing electrode 32 is arranged because the beam path is short, in order to improve the beam focusing characteristics, it is necessary to use a lens aperture that is somewhat larger than the beam diameter due to problems such as positioning. There is a limit to the function as an orifice. Also, when a lens is made of a thin film, it is necessary to make the insulator approximately the same as the lens aperture diameter for mechanical holding of each electrode, and it becomes a conduit function rather than an orifice function, resulting in a large conductance. There is a problem that the pressure ratio (vacuum degree ratio) cannot be increased.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide an electron beam apparatus which always holds an electron emitter in a high vacuum and stably emits an electron beam.

[0017]

The above object is to provide an electron beam for irradiating a sample in the sample chamber with a predetermined number of electron emitting parts provided in an electron gun chamber communicating with the sample chamber. In the device, a predetermined number of orifices formed by irradiating the beam at a predetermined position in the passage of the beam, having the same diameter as the beam, and forming a predetermined number of orifices positioned with respect to the beam. It is solved by providing a plate.

As a method of forming an orifice, a predetermined number of orifice plates of a predetermined material to be perforated by the beam are positioned at a predetermined position in the path of the beam, and the orifice plate is irradiated with the beam to perforate. Thereby forming an orifice having the same diameter as the beam and positioned with respect to the beam.

[0019]

As described above, at a predetermined position in the passage of the beam emitted from the electron gun chamber, a predetermined number of orifice plates having orifices for passing the beam are provided. The orifice is obtained by irradiating the positioned orifice plate with a beam to perforate it.

Therefore, the orifice has the same diameter as the beam and is formed in a state where it is already positioned with respect to the beam.

As a result, when a large number of beams are used,
Even if a large number of orifices are formed, it is possible to provide a difference in vacuum degree between the electron emitting portion and the sample chamber. That is, it is possible to always maintain the electron emitting portion in a high vacuum and to stably emit the beam.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a block diagram of an embodiment of the present invention.
In the electron beam device 51 of FIG. 1, an electron gun chamber 52,
It communicates with the sample chamber 53. A first orifice plate 54a is provided in the electron gun chamber 52, and the electron gun chamber 52 and the sample chamber 5 are provided.
The second orifice plate 54b is provided at the boundary with the third orifice plate 54b. Vacuum exhaust pumps 55a and 55b such as ion pumps and turbo pumps are connected to the electron gun chamber 52 and the sample chamber, respectively, so that the chambers are evacuated.

In the electron gun chamber 52, a minute cold cathode (emitter array) which is an electron emitting portion is used as an electron emitter 56.
A plurality of two-dimensionally arranged (may be one). An anode (anode) 57 is arranged below the electron emitter 56 as an electrode for extracting a beam, and below the anode 57, the first orifice plate 54a and the electrostatic lens focusing electrode 5 are arranged.
8, the deflection electrode 59, and the detector 60 are sequentially provided.
An acceleration electrode 61 is provided between the first orifice plate 54a and the anode 57.

Here, FIG. 2 shows a diagram for explaining the orifice plate of FIG. In FIG. 2, the electron emitter 5
Since the electrons emitted from 6 have a certain spread, the anode 57 and the accelerating electrode 61 constitute two parallel plate lenses, so that the electron beam 62 is narrowed on the first orifice plate 54a. It is possible to form a narrowed crossover.

In this case, as will be described later, the orifice 63a formed by the electron beam 62 in the first orifice plate 54a can be perforated to have a diameter of 1 μm, for example.

By arranging the orifice 63a below the electron beam 56 (anode 57) as described above, the conductance due to the difference in vacuum degree in the front and rear regions can be reduced, and a large pressure difference (vacuum degree Difference) can be secured.

For example, if the diameter of the orifice is made large in consideration of the positioning with the electron beam as in the conventional case, and 1000 of these are formed, the conductance becomes 1000 times and the pressure ratio becomes to 4 × 10 ^-2 . The degree of vacuum of the electron emitter is on the order of 10 ^-8 Torr. Therefore, the first orifice plate 54a is provided with 1000 μm of orifices 63a having a diameter of 1 μm.
In the case of individual formation, the pressure ratio in the front and rear regions is up to 4 × 10 ⁻⁴ , and the degree of vacuum in the electron emitter 56 portion can be in the order of ^{−10 −10} Torr.

Further, the second orifice plate 5 in FIG.
Also in 4b, a plurality of orifices 63b are formed corresponding to the electron beams 62 emitted from each electron emitter 56, similarly to the first orifice plate 54a.

In this case, the electron beam 62 is emitted from the sample chamber 53.
Since the sample is focused on, the second orifice plate 54
An orifice 63b formed on the
It has the same diameter and a spread, for example, several μm to several tens of μm
Is formed.

Thus, the second orifice plate 54b
Is provided at the boundary between the electron gun chamber 52 and the sample chamber 53, it is possible to maintain not only the electron emitter 56 but also the electron optical system such as the electrostatic lens focusing electrode 58 in a high vacuum. It is possible to prevent the contamination of carbides and the like due to the irradiation of the electron beam on the surface.

Although the electron beam apparatus 51 of FIG. 1 shows a case where both the first and second orifice plates 54a and 54b are provided, only one of them may be provided.

Therefore, FIG. 3 shows a diagram for explaining the orifice action of FIG. 3A and 3B, the area of the orifice 63a (63b) is now A [m
² ], the exhaust conductance (C) is 116 × 1
0 ⁵ · A [l / s], and the pressure ratio P ₁ / P ₀ in the case of pumping speed S [l / s] becomes C / (C + S). For example, when the exhaust rate is 1 [l / s] for the orifice 63a (64b) having a diameter of 10 μm, the pressure ratio P ₁ / P ₀ is
It becomes 4 × 10 ⁻⁵ , and even if the sample chamber 53 side has a degree of vacuum of about 10 ⁻⁶ Torr, the electron emitter 56 portion is about 10 ⁻¹¹ Torr.
The vacuum degree of the table can be maintained.

By the way, the vacuum exhaust pump 5 in FIG.
Although 5a and 55b have a small pumping speed (S ₀ ) of several tens [l / s], the structure of the electron emitter 56 itself forms a pumping conductance, and the effective pumping speed when this is C ₁ is , 1 / S ₁ = (1 / C ₁ ) + (1 /
It becomes as small as S ₀ ).

Here, FIG. 4 shows a diagram for explaining the operation of the multiple orifices. Orifice 64 as shown in FIG.
When a large number of C is formed, C ₁ becomes the sum of C of each orifice, and it is easy to exhaust the gas, and it is possible to prevent the effective exhaust speed from decreasing. As a result, the pumping speed in the above case is 1 [l / l
[s].

In this way, each electron emitter 56 can always be maintained in a high vacuum, and the electron beam 62 can be stably emitted.

Next, FIG. 5 shows a diagram for explaining the orifice formation. In addition, here, the first orifice plate 5
Although the orifice formation for 4a is shown, the same applies to the second orifice plate 54b.

First, in FIG. 5A, originally, the first
The orifice is still formed at the position where the refill plate 54a is provided.
Position it in the unmade state. First orifice plate
54a is an orifice plate made of, for example, thin film silicon
54a₁Resist 54a on top ₂Is applied
It Therefore, the electron beam 62 is first emitted from the electron emitter 56.
Exposure is performed by irradiating the first orifice plate 54a. After this
The resist mask is processed in the same way as the normal process.
Etch and punch the orifice plate of Con. Also,
As shown in FIG. 5B, on the first orifice 54a,
Exposure by enclosing a chlorine-based etching gas
The part is punched by electron beam assisted etching.
The refill 63a is formed.

As a result, at the first orifice plate 54a, at intervals of the respective electron beams 62 (electron emitters 56),
An orifice 63a having the same diameter as the electron beam 62 can be formed. Further, in this case, since the orifice 63a is formed by the electron beam 62, it is inevitably positioned.

Next, FIG. 6 shows a diagram for explaining another orifice formation in FIG. In FIG. 6, the electron emitter 5
6 and the polarity of the voltage applied to the anode 57 are reversed,
The anode 57 side is set to a negative potential and an inert gas such as helium (He) or argon (Ar) is sealed near the electron emitter 56.

For example, when Ar gas is filled, the helium atoms are ionized by the reverse electric field in the vicinity of the tip of the electron emitter 56 to be positively charged, and are sensed at the negative potential of the anode 57 to be emitted as an ion beam. That is, the helium ion beam 64 is emitted instead of the electron beam.

Unlike the electron beam, the argon ion beam 64 has a large mass and momentum, and by irradiating the argon ion beam 64, the orifice plate is physically scraped off to form the orifice 63a. Also by this method, the position of the orifice 63a and the electron beam 62
The position and the diameter of the orifice 63a and the diameter of the electron beam 62 can be matched at the same time.

[0042]

As described above, according to the present invention, by providing an orifice plate in which a predetermined number of orifices perforated by irradiation of the beam are formed at a predetermined position in the path of the beam, the electron emitting portion is always maintained. It can be kept in a high vacuum, stable emission of the beam can be performed, and thus high-speed pattern inspection or high-resolution writing can be performed at high speed.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a diagram for explaining the orifice plate of FIG.

FIG. 3 is a diagram for explaining an orifice action of FIG.

FIG. 4 is a diagram for explaining the action of multiple orifices.

FIG. 5 is a diagram for explaining formation of the orifice in FIG.

FIG. 6 is a view for explaining another orifice formation of FIG.

FIG. 7 is a configuration diagram of a conventional multi-beam electron beam apparatus.

FIG. 8 is a diagram for explaining a conventional differential pumping system.

[Explanation of symbols]

 51 electron beam device 52 electron gun chamber 53 sample chamber 54a, 54b first and second orifice plates 55a, 55b vacuum exhaust pump 56 electron emitter 57 anode 58 electrostatic lens focusing electrode 59 deflector 60 detector 61 acceleration electrode 62 electron Beam 63a, 63b, 64 Orifice

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location H01J 37/18 37/305 9172-5E

Claims (6)

[Claims] 1. An electron gun chamber (5) communicating with the sample chamber (53)
2) is provided with a predetermined number of electron emitting portions (56), and a beam (62) is emitted from the electron emitting portions (56) into the sample chamber (5).
In the electron beam device for irradiating the sample of 3), the beam (6) is pierced at a predetermined position in the passage of the beam (62) by irradiation of the beam (62, 64).
2, 64) and a predetermined number of orifice plates (54a, 54b) having a predetermined number of orifices (63) positioned with respect to the beams (62, 64). Electron beam device. 2. The electron beam apparatus according to claim 1, wherein the orifice plate (54a) is provided below the electron emitting portion. 3. The electron beam apparatus according to claim 1, wherein the orifice plate (54b) is provided at a boundary portion between the electron gun chamber (52) and the sample chamber (53). 4. An electron gun chamber (5) communicating with the sample chamber (53)
2) is provided with a predetermined number of electron emitting portions (56), and a beam (62) is emitted from the electron emitting portions (56) into the sample chamber (5).
3) An orifice forming method of forming orifices (63a, 63b) in the electron gun chamber (52) of an electron beam device (51) for irradiating a sample, comprising: a predetermined position in a passage of the beam (62); Positioning a predetermined number of orifice plates (54a, 54b) of a predetermined material to be perforated by the beams (62, 64), and the beam (62, 54b) on the orifice plates (54a, 54b).
64) by irradiating and puncturing the beam (6
2, 64), and forming an orifice (63a, 63b) having the same diameter as that of the beam (62, 64) and positioned with respect to the beam (62, 64). 5. An electron beam (62) is emitted by introducing an active gas into the electron emitting portion (56) to irradiate the orifice plate (54a, 54b), and the orifice (63a, 54a, 54b) is subjected to electron beam assisted etching. 63b) is formed, The orifice formation method of Claim 4 characterized by the above-mentioned. 6. A field ionization ion beam (64) is emitted by introducing an inert gas into the electron emission portion (56),
The electric field ionization ion beam (64) is applied to the orifice plates (54a, 54b) so that the orifice (63
5. The method for forming an orifice according to claim 4, wherein a, 63b) are formed.