JP2001006594A - Liner tube and charged particle beam device having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liner tube having advantages such as no need to develop expensive devices and no concern to be crashed by an atmospheric pressure. SOLUTION: This liner tube 4 has a ceramic cylinder and a metallized layer and platimun plated layer 12 formed on the inner surface of the cylinder. Since the ceramic cylinder is an insulator and does not block a high-frequency alternating field, it does not interfere with effects of an electromagnetic lens or electromagnetic deflector disposed outside the liner tube. The metallized layer prevents electrification on the inner surface and can prevent harmful electric fields from generating. Existence of the platinum layer 12 hardly grows contaminations on the liner tube surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a liner tube disposed in an optical lens barrel of an electron beam exposure apparatus or the like. The invention also relates to a charged particle beam device having such a liner tube. In particular, the present invention relates to a liner tube suitable for an electron beam transfer exposure apparatus intended to form a high-density pattern having a minimum line width of 0.1 μm or less at a high throughput.

[0002]

2. Description of the Related Art In an electron beam exposure apparatus, a liner tube for keeping an electron beam optical path around an optical axis in a vacuum atmosphere is provided in an optical lens barrel. Vessel is located. As a specific material and structure of such a liner tube, there are known a ceramic cylinder in which the inner surface of a ceramic cylinder is sputter-coated with Ti or platinum, and a high-resistance metal such as Ti which is thinly cut. 57-68027, 57
-88660, 57-92745, 59-5742
5).

[0003]

Of the above-mentioned prior arts, those using sputter coating require the development of a dedicated apparatus because a normal sputter coating apparatus is not suitable for coating the inner surface of the cylinder. Yes and expensive. On the other hand, the method of shaving Ti thinly requires a processing cost. Also, if there is a part that is too thin, the liner tube may be crushed at atmospheric pressure. Further, when it is necessary to provide an opening inside the liner tube, the above two techniques require the liner tube to be divided into two parts, which complicates the structure. In that case, there was a problem that the surface area of the vacuum equipment was increased.

[0004] The present invention has been made in view of such a conventional problem, there is no need to develop an expensive device, there is no fear of being crushed by the atmospheric pressure, or an opening can be provided in the middle. It is an object of the present invention to provide a liner tube having such advantages. Another object is to provide a charged particle beam device including such a liner tube.

[0005]

Means for Solving the Problems and Embodiments of the Invention To solve the above problems, a liner tube according to the present invention comprises:
A liner tube disposed in a charged particle beam optical lens barrel, comprising: a cylindrical body made of ceramic; and a metallized layer formed on an inner surface of the cylindrical body.

[0006] Since the ceramic cylinder is an insulator and does not shield a high-frequency alternating magnetic field, it does not hinder the operation of the electromagnetic lens and the electromagnetic deflector outside the liner tube. The metallized layer can prevent charging of the inner surface of the liner tube, and can prevent generation of a harmful electric field. In this specification, the metallized layer means a layer in which a metal layer is baked on a ceramic surface, and does not include a metal layer formed on a ceramic surface by a method such as sputter coating.

The liner tube of the present invention preferably further comprises a platinum plating layer formed on the inner surface of the metallized layer. Due to the presence of the platinum plating layer,
Contamination does not easily grow on the surface of the liner tube. Further, it is hardly oxidized when performing oxygen radical cleaning for removing contamination.

Further, in the liner tube of the present invention, the metallized layer contains titanium. Since Ti has a relatively high electric resistance in a metal, eddy current does not frequently occur in a high-frequency alternating magnetic field, and can be used as a liner tube even if the thickness of the metallized layer is somewhat increased. In the case of performing platinum plating, plating easily adheres to the metallized layer.

The liner tube according to the present invention is characterized in that the cylindrical body is made of AlN or high heat conductive SiC. AlN, for example, 95 to 99.5%, has a thermal conductivity of about 60 to 170 W / m ° K. In addition, high thermal conductivity SiC, for example, Hitaceram SC-101 manufactured by Hitachi, Ltd., has a thermal conductivity of about 270 W / m ° K. In this case, even when a beam with a high accelerating voltage is used, heat can be efficiently released to the outside, so that problems associated with a rise in the temperature of the liner tube (gas release, temperature fluctuations of lenses and deflectors, etc.) can be avoided.

A liner tube according to another aspect of the present invention has a step on the inner surface of the tube, and an opening plate is disposed on the step, and the opening plate is fixed to the tube in a spot manner with a brazing material. It is characterized by having been done. As the aperture plate, there are an aperture plate for differential exhaust and an aperture plate for beam shaping / trim. Delay of the deflecting magnetic field due to eddy current can be made without any problem. The amount of the brazing may be small because it is sufficient not to perform vacuum sealing but to simply prevent the opening from coming off.

The charged particle beam apparatus according to the present invention is characterized in that:
A liner tube according to any one of the above, and an electromagnetic lens or an electromagnetic deflector arranged outside the liner tube.

Hereinafter, description will be made with reference to the drawings. FIG.
1 is a sectional view of a liner tube according to one embodiment of the present invention. The liner tube 4 has a hollow cylindrical shape as a whole, and has a large-diameter portion 4a, a small-diameter portion 4c, and a step 4b connecting the both. Each part has a titanium metallized layer + a platinum plated layer 12 on the inner surface of a ceramic cylinder.
Having. The inner hole of the liner tube 4 becomes an optical path of the electron beam.

An aperture plate 13 made of platinum is placed on the step 4b. An opening 13a through which an electron beam passes is formed in the center of the opening plate 13. The end of the opening 13 a is brazed and fixed using a brazing material 14.
This brazing does not need to be vacuum-sealed, and it is sufficient if it is mechanically fixed, so that the brazing material is minimized, and no eddy current is generated to a problem.

A method for manufacturing the liner tube will be described. Using Al ₂ O ₃ as a ceramic cylinder,
The inner surface is titanium metallized.

FIG. 2 is an explanatory view of a method of platinum plating the liner tube of FIG. The inner surface of the liner tube 4 is metallized with titanium as described above. The platinum rod 3 is inserted into the inner hole 4d of this cylinder, and the platinum rod electrode is fixed to the center of the inside of the cylinder. Then, the whole is immersed in the plating solution 6 and connected to the plating power supply 1 to flow a current to perform platinum plating. A platinum disk 7 is provided at an appropriate place of the platinum electrode so that the step portion 4b is also sufficiently plated. When the liner tube is long, the plating solution is caused to flow by the propeller 8 so that the plating solution is sufficiently supplied. The plating is about 10 μm thick.

Next, as shown in FIG. 1, the platinum-plated liner tube 4 has the large-diameter side 4a facing upward and the platinum opening 13 is dropped. In the periphery of the platinum opening 13,
A very small amount of brazing material 14 made of an alloy of silver and copper is placed in two places in advance. After confirming that the opening plate 13 is in the proper position, the opening plate 13 is placed in a hydrogen furnace, and the opening plate and the liner tube are brazed by high-frequency heating from the outside.

FIG. 3 is a schematic sectional view showing the overall configuration of the optical system of the electron beam transfer exposure apparatus according to one embodiment of the present invention. The cathode 113 of the electron gun is shown at the top of the figure. The cathode 113 has an electron emission surface 113a. This cathode 113 has a negative high voltage (Vk,
60 KV) is applied. A hollow beam is emitted from the electron emission surface 113a.

A liner tube 117 of an illumination lens system also serving as an anode is arranged below the cathode 113. The liner tube 117 has a hollow cylindrical shape with a brim at the upper end, and the main body is made of ceramics, which is an insulating material. A metal film 117a (titanium metallized layer plus platinum plating) is coated on the upper end surface (upper surface of the flange) and the inner surface of the liner tube 117. A positive high voltage (for example, +40 KV) is applied to the metal film 117a. Metal film 11 on the upper end surface of liner tube 117
7a serves as the anode of the electron gun. The acceleration voltage between the cathode 113 and the anode 117a in this example is 40-(-60) = 100 KV.

The illumination optical system of this electron beam transfer exposure apparatus includes a total of three lenses (a first condenser lens 123, a second condenser lens 129, and an illumination lens 133).
Each of the lenses 123, 129, 133 has a rotationally symmetric hollow magnetic pole 123a, 129a, 13
3a. Each magnetic pole forms a magnetic circuit of each lens. Inside each of the magnetic poles 123a, 129a, 133a,
An exciting coil (a portion indicated by X) in which the coil is wound around the optical axis is arranged.

The above-mentioned liner tube 117 is fitted into the inside diameter of each of the lenses 123, 129 and 133.
A blanking deflector 125 is arranged below the first condenser lens 123. A molding opening 127 is arranged inside the liner tube 117 at the same height position as the upper magnetic pole of the second condenser lens 129. Similarly, a blanking opening 131 is arranged inside the liner tube 117 at the same height position as the upper magnetic pole of the illumination lens 133.

A ferrite stack 135 is fitted into the inner periphery of the illumination lens 33, and an illumination beam deflector 137 is fitted inside the ferrite stack 135. The ferrite stack 135 is formed by alternately stacking insulator rings and ferrite rings.
7 is shielded so that the high frequency magnetism does not leak outside. The deflectors 137 are provided on the outer periphery of the liner tube 117 in five stages in the optical axis direction. Magnetic pole 1 of illumination lens 133
A ferrite magnetic pole 139 is arranged on the inner periphery of 33a.

The operation of the illumination optical system will be described. First
The condenser lens 123 forms a crossover image formed by an electron beam emitted from the electron emission surface 113 a of the cathode 113 on the forming aperture 127. The shaping aperture 127 shapes the outer shape of the illumination beam and has a shape and dimensions for illuminating one unit exposure pattern area (subfield) on the mask (for example, a square with a side of slightly more than 1 mm on the mask). The blanking deflector 125 deflects the electron beam when it is not desired to irradiate the mask 151 with the illumination beam, and hits the opening plate of the blanking opening 131 to cut off the beam.

The second condenser lens 129 forms a crossover image at the position of the blanking aperture 131. The illumination lens 133 forms an image of the shaping aperture 127 on the mask 151. Illumination beam deflector 1 in illumination lens 133
37 deflects the illumination beam at high speed in the plane perpendicular to the optical axis.
By this deflection, many subfields formed on the mask 151 are sequentially illuminated. By scanning the stage on which the mask is mounted and the stage on which the wafer is mounted, it is possible to expose a wide area beyond the visual field of the optical system.

Below the illumination lens 133, a mask 151 is provided.
Is arranged. A pattern to be transferred to the wafer is formed on the mask 151. A positive high voltage (for example, 60 KV) is applied to the mask 151. Electron gun cathode 11
The acceleration voltage applied between 3 and the mask 151 is +60 KV−
(−60 KV) = 120 KV. The voltage difference between the mask 151 and the liner tube 117 of the illumination optical system is +60.
KV−40 KV = 20 KV.

Between the mask 151 and the wafer 191, 2
A projection optical system including a projection lens of a step (first projection lens 159, second projection lens 173) is provided. By these projection lenses 159 and 173, the pattern on the mask is reduced (for example, 1/4) and transferred onto the wafer. In this exposure apparatus, exposure is performed for each subfield of the mask, and an image of the subfield is projected onto an appropriate position on the wafer. Each projection lens 159, 1
Reference numeral 73 denotes a rotationally symmetric hollow magnetic pole whose cross section is inwardly U-shaped. Each magnetic pole forms a magnetic circuit of each lens. Inside each magnetic pole, an exciting coil (a portion indicated by a cross) in which the coil is wound around the optical axis is arranged.

Liner tubes 155 and 177 are fitted around the inner circumference of each of the lenses 159 and 173. The liner tubes 155 and 177 have a hollow cylindrical shape with a brim at an upper end or a lower end, and a main body is made of a ceramic material which is an insulating material. A metal film 155a is coated on the upper end surface (upper surface of the flange) and the inner surface of the upper liner tube 155. On the other hand, the lower liner tube 177
Is also coated with a metal film 177a. A positive high voltage (for example, +40 KV) is applied to these metal films 155a and 177a.

A contrast opening 171 is arranged on the inner surface of the lower end of the liner tube 155. The position where the contrast opening 171 is located is a point at which the space between the mask and the wafer is internally divided at a reduction ratio, and a point at which a crossover image of the electron gun of the illumination system is formed. The contrast opening 171 blocks an electron beam scattered by a non-pattern portion of the mask 151.

A ferrite stack 161 formed by stacking an insulator ring and a ferrite ring is fitted inside the lens excitation coil between the upper and lower magnetic poles 157 on the inner periphery of the first projection lens 159. The ferrite stack 161 is for sealing so that the high frequency magnetism of the coils inside the ferrite stack 161 does not leak outside. Upper and lower magnetic poles 15
The inside diameter (bore diameter) of 7 is smaller than the inside diameter of the ferrite stack 161.

Inside the ferrite stack 161, 4
Stage aberration correction deflector 163, astigmatism correction coil 165,
A dynamic focus coil and a magnification / rotation correction coil 166 are provided. Aberration correction deflector 163
Eliminates third-order geometrical optical aberrations (T. Hosokawa, Opt.
ik, 56, No. 1 (1980) 21-30). Astigmatism correction coil 1
Reference numeral 65 denotes a coil for correcting astigmatism. The dynamic focus coil / magnification / rotation correction coil 166 adjusts the focus of the projection lens 12 and also adjusts the rotation and magnification.

The second projection lens 173 basically reduces the first projection lens 159 in a similar manner to a reduction ratio (for example, 1/4).
It is small and inverted. Further, it is configured to satisfy the following condition of the symmetric magnetic doublet. That is, the distance from the crossover CO to the magnetic poles of both lenses, the Bohr diameter (magnetic pole inner diameter) ratio, and the lens gap (the height of the magnetic pole in the optical axis direction) ratio are set by the first projection lens 159 and the second projection lens 173 to 4: It is set to 1.

The first projection lens 173 has the first
Similarly to the projection lens, a four-stage aberration correction deflector 183, astigmatism correction coil 185, dynamic focus coil and magnification / rotation correction coil 186 are arranged. Aberration correction deflectors and coils in both lenses are crossover
They are arranged symmetrically with respect to CO. Each pair of deflectors and coils is connected in series to one control power supply (not shown).

In the projection optical system of this embodiment, an astigmatism correction coil 181 is also arranged at the position of the contrast aperture 171 between the first projection lens 159 and the second projection lens 173.

Below the second projection lens 173, a wafer (sensitive substrate) 191 is arranged. A resist is applied on the wafer 191, and an electron beam dose is applied to the resist to transfer a pattern on the mask 151. In this example, the wafer 191 is electrically grounded. Therefore, the metal film 177a on the lower end surface of the liner tube 177 of the second projection lens 173 and the wafer 19
Between 1, there is a deceleration electric field of Vp-0 = 40 kV.

[0034]

As is apparent from the above description, according to the present invention, a liner tube having an inner metallized layer capable of preventing the inner surface of the liner tube from being charged can be provided without developing an expensive manufacturing apparatus. Further, a charged particle beam device having such a liner tube and capable of forming a pattern with high precision can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view of a liner tube according to one embodiment of the present invention.

FIG. 2 is an explanatory view of a method of plating the liner tube of FIG. 1 with platinum.

FIG. 3 is a schematic cross-sectional view illustrating the entire configuration of an optical system of an electron beam transfer exposure apparatus according to one embodiment of the present invention.

[Explanation of symbols]

2,5 Insulator jig 3 Platinum rod 4 Liner tube 4a Large diameter part 4b Step part 4c Small diameter part 4d
Inner hole 6 Plating solution 7 Platinum disk 8 Propeller 13 Platinum opening 113 Cathode 113a Electron emission surface 115 Control anode 117 Liner tube 123 First condenser lens 123a, 129a, 133a Magnetic pole 125 Deflector 127 Molded opening 129 Second condenser lens 131 Blanking aperture 133 Illumination lens 135 Ferrite stack 137 Deflector 139 Ferrite pole 141, 153 Hollow disk 151 Mask 155, 177 Liner tube 155a, 17
7a Metal film 157 Upper and lower magnetic poles 159 First
Projection lens 161 Ferrite stack 163 Aberration correction deflector 165 Astigmatism correction coil 166 Dynamic focus coil and magnification / rotation correction coil 171 Contrast aperture 173 Second projection lens 181 Astigmatism correction coil 183 Aberration correction deflector 185 Astigmatism correction coil 185 186 Dynamic focus coil and magnification / rotation correction coil 191 Wafer

Claims (6)

[Claims] 1. A liner tube disposed in a charged particle beam optical lens barrel, comprising: a cylindrical body made of ceramic; and a metallized layer formed on an inner surface of the cylindrical body. . 2. The liner tube according to claim 1, further comprising a platinum plating layer formed on an inner surface of said metallized layer. 3. The liner tube according to claim 1, wherein said metallized layer contains titanium. 4. The liner tube according to claim 1, wherein said cylindrical body is made of AlN, Al ₂ O ₃ or high thermal conductive SiC. 5. A liner tube disposed in a charged particle beam optical column; having a step on an inner surface of the tube, an opening plate being disposed on the step, and the opening plate being spot-shaped. A liner tube fixed to the tube with brazing material. 6. A charged particle beam apparatus comprising: the liner tube according to claim 1; and an electromagnetic lens or an electromagnetic deflector disposed outside the liner tube.