JP2001144000A - Charged particle beam transferring apparatus, cleaning method thereof and device manufacturing method using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charged particle beam transferring apparatus and its cleaning method which decreases the growing rate of contamination and is capable of cleaning easily and surely, without causing secondary effects if the contamination occurs. SOLUTION: The charged particle beam transferring apparatus has a projection optical system with two stages of projection lenses 12, 14 with a vacuum chamber 25 formed between the two stages of projection lenses. A vacuum pipe 33 connected to a vacuum pump 35 is connected to the vacuum chamber 25, a vacuum piping 36 for feeding an active gas for cleaning a charged particle beam passage in the projection lenses is opened at one end in the vacuum chamber 25, and an apparatus 38 for producing the active gas is connected to the other end of the piping 36. The vacuum chamber 25 is evacuated to reduce the growth/accumulation of contaminations, and the contaminations, if accumulating, can be appropriately removed by the active gas such as oxygen radicals, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a charged particle beam transfer apparatus designed to form the following fine and high-density patterns at high throughput, a cleaning method thereof, and a high-precision device manufacturing method. In particular, the present invention relates to a method for preventing contamination between the projection lenses of a charged particle beam transfer device or the like due to contamination and beam instability.

[0002]

2. Description of the Related Art An electron beam exposure apparatus will be described as an example.
2. Description of the Related Art Conventionally, the following three methods have been used as methods for preventing charging due to contamination in an optical lens barrel without disassembling the lens barrel. (1) Cleaning is performed by irradiating an electron beam to a contaminated portion with an oxidizing gas flowing inside the lens barrel. (2) An oxidizing gas is introduced into the lens barrel, and a high-frequency voltage is applied between the metal part insulated from the ground and the ground,
Discharge is generated inside to generate plasma, and dirt is decomposed and removed by oxygen plasma. (3) An introduction port for flowing radicals into the lens barrel and an exhaust port for exhausting reaction products are provided, discharge occurs outside the lens barrel, and oxygen radicals flow from the electron gun side into the lens barrel to remove dirt. Downflow ashing). These methods are disclosed in JP-A-63-308856 and the like.

[0003]

In an electron beam transfer apparatus for transferring a large area pattern at a time, a beam current 10 to 100 times larger than that of a conventional electron beam lithography apparatus flows.
Therefore, the speed at which contamination occurs is high, and the contamination grows to a degree that causes a problem in a short time. Further, since such a charged particle beam transfer apparatus requires high accuracy, even if the beam becomes unstable even a little, a predetermined pattern transfer accuracy specification cannot be satisfied.

In particular, contamination easily adheres to the inside of the two-stage projection lens of the projection optical system. This part
This is the part that most affects the pattern transfer accuracy when charging up with contamination attached. SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and it is a charged particle beam transfer that can reduce the growth rate of contamination and can easily and reliably clean even if contamination occurs without causing side effects. An object of the present invention is to provide an apparatus and a cleaning method thereof, and to provide a more accurate device manufacturing method.

[0005]

According to a first aspect of the present invention, there is provided a charged particle beam transfer apparatus for illuminating a reticle having a pattern to be transferred onto a sensitive substrate with a charged particle beam. A charged particle beam transfer apparatus, comprising: a system, a projection optical system for reducing and projecting a charged particle beam passing through a reticle onto a sensitive substrate, and a liner tube defining a charged particle beam path of each optical system; The projection optical system includes a two-stage projection lens, and a liner tube between the two stages of projection lenses is provided with an exhaust port of an exhaust pipe connected to a vacuum pump. By evacuating the liner tube between the two projection lenses with a vacuum pump, it is possible to reduce the growth and accumulation of contamination in the charged particle beam passage in the projection lens.

A charged particle beam transfer apparatus according to a second aspect of the present invention comprises: an illumination optical system for illuminating a reticle having a pattern to be transferred onto a sensitive substrate with a charged particle beam; and a charged particle beam passing through the reticle onto the sensitive substrate. A charged particle beam transfer device comprising: a projection optical system for reducing projection imaging; and a liner tube for defining a charged particle beam path of each optical system; One end of a pipe for supplying an active gas for cleaning the charged particle beam passage in the projection lens is opened in a liner tube between the projection lenses of the step, and the other end of the pipe is connected to the other end of the pipe via a valve. A device for generating gas is connected. For example, an oxygen radical as an active gas is supplied to a liner tube between two projection lenses to remove contamination in a charged particle beam passage in the projection lens.

A charged particle beam transfer apparatus according to a third aspect of the present invention comprises: an illumination optical system for illuminating a reticle having a pattern to be transferred onto a sensitive substrate with a charged particle beam; and a charged particle beam passing through the reticle onto the sensitive substrate. A charged particle beam transfer device comprising: a projection optical system for reducing and projecting images; and a liner tube for defining a charged particle beam path of each optical system; said projection optical system comprising a two-stage projection lens; An exhaust pipe connected to a vacuum pump is connected to a liner tube between the projection lenses of the stages through a valve. Further, the liner tube has an activity for cleaning a charged particle beam passage in the projection lens. One end of a pipe for supplying gas is open, and a device for generating the active gas is connected to the other end of the pipe via a valve. The liner tube is evacuated to reduce the growth and accumulation of contamination. Further, even if the contamination accumulates, it can be appropriately removed by an active gas such as an oxygen radical.

[0008] A charged particle beam transfer apparatus according to a fourth aspect of the present invention is a charged particle beam transfer apparatus including an optical lens barrel that houses an optical system from an energy ray light source to a sample; and accommodates a sensitive substrate (wafer). A reticle chamber for accommodating a pattern original (reticle) to be transferred to the sensitive substrate, and a charged particle beam path of the optical lens barrel between the wafer chamber and the reticle chamber. A liner tube is formed,
The liner tube is provided with means for introducing oxygen or oxygen radicals, and means for preventing the introduced oxygen or oxygen radicals from flowing into the wafer chamber or the reticle chamber. By allowing oxygen or oxygen radicals to stay longer in the liner tube, these gases can be filled up to the details in the chamber, and can be more reliably brought into contact with the contamination and removed.

In these embodiments, it is preferable that a contrast opening is disposed in the liner tube. Further, it is preferable that an exhaust route for increasing the vacuum conductance is formed in the contrast opening. The contrast aperture usually has a diameter of about 100 μm and a small conductance. Therefore, by forming an exhaust route around the contrast opening, gas and oxygen radicals can easily flow.

[0010] The cleaning method of the charged particle beam transfer apparatus according to the aspect of the present invention includes an illumination optical system for illuminating a reticle having a pattern to be transferred onto a sensitive substrate with a charged particle beam, and a charged particle beam passing through the reticle on the sensitive substrate. A method for cleaning a charged particle beam transfer apparatus, comprising: a projection optical system for reducing and projecting an image on a projection surface; and a liner tube for defining a charged particle beam path of each optical system; An active gas is supplied to the liner tube to clean the charged particle beam passage in the projection lens. By supplying an active gas such as oxygen radicals to the liner tube between the two projection lenses, the growth and accumulation of contamination in the charged particle beam passage in the projection lens can be reduced.

A device manufacturing method according to an aspect of the present invention provides at least one layer of lithography using the charged particle beam transfer apparatus according to any one of the above-described aspects or the charged particle beam transfer apparatus cleaned by the cleaning method according to the above-described aspect. According to these methods, fine and high-density patterns can be manufactured with high throughput and high accuracy.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. First, a configuration example of an entire exposure apparatus using an electron beam, which is a kind of charged particle beam, will be described. FIG. 3 is a diagram illustrating an example of the image forming relationship and the configuration of a control system in the entire optical system of the electron beam projection exposure apparatus of the division transfer system. The electron gun 1 arranged at the uppermost stream of the optical system emits an electron beam downward. Two stages of condenser lenses 2 and 3 are provided below the electron gun 1, and the electron beam is converged by these condenser lenses 2 and 3 to form a blanking aperture 7.
The crossover CO is imaged.

A rectangular opening 4 is provided below the condenser lens 3.
Is provided. The rectangular aperture (illumination beam shaping aperture) 4 allows only an illumination beam that illuminates one subfield (unit exposure pattern area) of the reticle (mask) 10 to pass. The aperture 4 forms the illumination beam into a square having a size of slightly more than 1 mm square (example) in reticle size conversion.
The image of the opening 4 is formed on the reticle 10 by the lens 9.

Below the beam shaping aperture 4, a blanking deflector 5 is arranged. The deflector 5 deflects the illumination beam to hit the non-opening of the blanking opening 7,
The beam does not hit the reticle 10. An illumination beam deflector 8 is arranged below the blanking opening 7. The deflector 8 mainly scans the illumination beam sequentially in the horizontal direction in FIG. 3 to illuminate each subfield of the reticle 10 within the field of view of the illumination optical system. A condenser lens 9 is disposed below the deflector 8. The condenser lens 9 converts the electron beam into a parallel beam,
0, the beam forming aperture 4 is imaged on the reticle 10.

Although the reticle 10 shows only one subfield on the optical axis in FIG. 3, it actually extends in a plane perpendicular to the optical axis (XY plane) and has many subfields. On the reticle 10, a pattern (chip pattern) forming one semiconductor device chip as a whole is formed.

To illuminate each subfield within the field of view of the illumination optical system, the electron beam can be deflected by the deflector 8 as described above. To illuminate each subfield beyond the field of view of the illumination optical system, the reticle 10 is mounted on a reticle stage 11 that can move in the X and Y directions.

Below the reticle 10, projection lenses 12 and 14 and a deflector 13 are provided. Then, an illumination beam is applied to a certain subfield of the reticle 10, and the electron beam passing through the pattern portion of the reticle 10 is reduced by the projection lenses 12 and 14 and deflected by the deflector 13 to be The image is formed at the position. An appropriate resist is applied on the wafer 15, and the resist is given a dose of an electron beam, and the pattern on the reticle is reduced and transferred onto the wafer 15.

A crossover CO is formed at a point where the distance between the reticle 10 and the wafer 15 is internally divided at a reduction ratio.
A contrast opening 18 is provided at the crossover position. The opening 18 blocks the electron beam scattered by the non-pattern portion of the reticle 10 from reaching the wafer 15.

A wafer (sensitive substrate) 15 is moved via an electrostatic chuck 16 to a wafer stage 1 movable in XY directions.
7. By synchronously scanning the reticle stage 11 and the wafer stage 17 in directions opposite to each other, it is possible to sequentially expose a large number of subfields arranged in a chip pattern. In addition, both stages 11 and 17 are equipped with an accurate position measuring system using a laser interferometer, and the stage position is accurately measured.

Each of the lenses 2, 3, 9, 12, 14 and each of the deflectors 5, 8, 13 are provided with a respective coil power supply 2a, 3a.
a, 9a, 12a, 14a and 5a, 8a, 13a. The reticle stage 11 and the wafer stage 17 are also controlled by the control unit 21 via the stage drive motor control units 11a and 17a.
Is controlled by The electrostatic chuck 16 is connected to the main controller 2 via the electrostatic chuck controller 16a.
Controlled by 1. The reticle 1 on the wafer 15 is controlled by accurate stage position and optical system control.
The reduced images of the subfields on 0 are accurately joined,
The entire chip pattern on the reticle is transferred onto the wafer.

FIG. 1 is an enlarged view showing the vicinity of a projection optical system of a charged particle beam transfer apparatus according to an embodiment of the present invention. The charged particle beam transfer device of this example includes a reticle-side projection lens 12 and a wafer-side projection lens 14 (two-stage projection lens).
Having. Both lenses have a hollow cylindrical shape, and the central hole is isolated from the outside by tubes 26 and 27. The inside of the tubes 26 and 27 is a charged particle beam passage in a vacuum atmosphere. A liner tube 25 is provided at the center between the projection lenses 12 and 14. The contrast opening 18 is arranged in the liner tube 25.

On the outer periphery of the reticle side liner tube 26, the reticle side projection lens 12, the ferrite stack 2
8, the deflector 13 is arranged. In the wafer-side liner tube 27, a wafer-side projection lens 14, a ferrite stack 28 ', and a deflector 13' are arranged. The ferrite stacks 28, 28 'are magnetic shields for shielding high-frequency waves of the deflectors 13, 13' from leaking outside. A contrast opening 18 is provided in the liner tube 27 on the wafer side. Each liner tube 26, 2
Reference numeral 7 denotes a structure (an example) in which platinum is coated on the inside of a ceramic.

A vacuum pipe 33 extends from the liner tube 25 in a direction perpendicular to the optical axis. This vacuum pipe 33
Is connected to a sputter ion pump 35 via a valve 34. Further, another vacuum pipe 36 is drawn from the liner tube 25 in the opposite direction. The oxygen radical generator 3 is connected to the vacuum pipe 36 via a valve 37.
8 are connected. The oxygen radical generator 33 receives a high voltage from the high voltage power supply 39 to generate a high frequency discharge,
Generates oxygen radicals.

A jig 40 is mounted on the wafer stage 17. By moving the wafer stage 17, the jig 4
When the upper surface of O is positioned toward the lower end surface of the casing 41 of the wafer-side projection lens 14, a slight gap is formed between the upper surface of the jig 40 and the lower end surface of the casing 41. The jig 40 may be always installed at the end of the wafer stage 17, or a jig that can be chucked by an electrostatic chuck may be inserted from the loading chamber.

Further, a means for inhibiting oxygen radicals from flowing into the reticle chamber is also provided on the reticle side. This is, for example, on the underside of the reticle stage,
A jig similar to the jig for the wafer stage may be placed. When the reticle stage is moved to position the jig toward the upper end surface of the reticle-side liner tube 26, a slight gap is formed between the lower end surface of the jig and the upper end surface of the reticle-side liner tube 26. You.

FIGS. 2A and 2B are enlarged views of the vicinity of the contrast aperture of the charged particle beam transfer apparatus of FIG. 1, wherein FIG. 2A is a sectional view and FIG. 2B is a bottom view. Contrast aperture plate 43
Has a contrast aperture 18 formed on the optical axis.
A plurality of slit-shaped openings 45 are formed around the opening 18. The peripheral slit-shaped opening 45 has a larger area than the opening 18 on the optical axis. Due to the slit-shaped opening 45, the vacuum conductance above and below the contrast opening 18 is increased. In the wafer lens side liner tube 27,
Above the contrast opening 18, another opening plate 4 is provided.
1 is installed. The aperture plate 41 has an aperture 42 on the optical axis.
Having. The opening 42 has a larger area than the contrast opening 18. The slit-shaped opening 45 of the contrast opening plate 43 is shielded by the opening plate 41.

Next, the cleaning method will be described.
To perform cleaning, first, the wafer stage 17 is moved, and the jig 40 on the stage 17 faces the lower end surface of the projection lens casing 31. That is, the entrance to the wafer chamber is substantially closed. At this time, the reticle stage side is similarly treated.
Inside the liner tube 25 is usually a sputter ion pump 3
A vacuum is drawn at 5. Pump 3 for cleaning
The valve 34 at the front side is closed, and the oxygen radical generator 38 is closed.
To generate oxygen radicals, and open the valve 37 to supply oxygen radicals to the liner tube 25.

At this time, the entrance of the lower end of the wafer-side liner tube 27 into the wafer chamber is located on the wafer stage 1.
7 is almost completely closed by the jig 40.
Similarly, the entrance of the reticle-side chamber is almost completely closed by the reticle stage jig. Around the contrast opening 18, there is a slit-shaped opening 45, which has a large vacuum conductance. Furthermore, by providing the contrast aperture plate 41, oxygen radicals flow from the contrast aperture 18 through the aperture 42 of the aperture plate 41, as shown in FIG. Thus, the liner tube 2
The oxygen radicals flowing into 5 flow into liner tube 26 on the reticle side and into liner tube 27 on the wafer side. Then, oxygen radicals are supplied to the liner tubes 26 and 27.
Fill inside and clean. Although a slight gap is formed between the upper surface of the jig 40 and the lower end surface of the wafer-side liner tube casing 41, this gap collides with the wall of each surface when oxygen radicals pass, and loses activity. The width is adjusted as follows. Therefore, oxygen radicals hardly flow into the wafer chamber, and oxidation of the wafer chamber can be suppressed. The same applies to the reticle side.

As described above, since oxygen radicals are retained in the liner tube 25 and the wafer-side liner tube 27, the oxygen radicals reach all corners in the liner tube 25, thereby ensuring contamination around the contrast opening 18. Can be removed.

Next, an embodiment of a device manufacturing method using the above-described charged particle beam transfer exposure apparatus will be described. FIG.
Shows a flow of manufacturing micro devices (semiconductor chips such as ICs and LSIs, liquid crystal panels, CCDs, thin-film magnetic heads, micro machines, etc.).

In step 1 (circuit design), a circuit of a semiconductor device is designed. Step 2 (reticle fabrication) forms a reticle on which the designed circuit pattern is formed. At this time, the effect of beam blur is removed by locally resizing the pattern. On the other hand, in step 3 (wafer manufacturing), a wafer is manufactured using a material such as silicon.

In step 4 (oxidation), the surface of the wafer is oxidized. Step 5 (CVD) forms an insulating film on the wafer surface. Step 6 (electrode formation) forms electrodes on the wafer by vapor deposition. Step 7 (ion implantation) implants ions into the wafer. In step 8 (resist processing), a photosensitive agent is applied to the wafer. Step 9 (electron beam exposure) uses the reticle created in step 2 by an electron beam transfer device.
The circuit pattern of the reticle is printed and exposed on the wafer. In step 10 (light exposure), a circuit pattern of the reticle is printed and exposed on the wafer by an optical stepper. Before or after this, proximity effect correction exposure for equalizing the backscattered electrons of the electron beam may be performed. Although this example is an example of so-called mix-and-match exposure of an electron beam and light, it is needless to say that the entire circuit layer may be formed only by the electron beam exposure.

In step 11 (development), the exposed wafer is developed. In step 12 (etching), portions other than the resist image are selectively removed. Step 13
In (resist removal), the unnecessary resist after etching is removed. By repeatedly performing steps 4 to 13, multiple circuit patterns are formed on the wafer.

Step 14 (assembly), which is called a post-process, is a process of forming a semiconductor chip using the wafer produced by the above process, and includes an assembly process (dicing and bonding) and a packaging process (chip encapsulation). And the like. In step 15 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device manufactured in step 14 are performed. Through these steps, a semiconductor device is completed and shipped (step 16).

[0035]

As is apparent from the above description, according to the present invention, a liner tube is formed between two projection lenses, and a vacuum pump is connected to the liner tube to evacuate the projection lens. Contamination can be prevented from accumulating in the charged particle beam path of the lens. In addition, by connecting an oxygen radical generator to the liner tube and supplying oxygen radicals, even if contamination accumulates, it can be removed immediately. Therefore, the growth rate of contamination can be reduced, and even if contamination occurs, cleaning can be performed easily, reliably, and without giving any side effects.

[Brief description of the drawings]

FIG. 1 is an enlarged view showing the periphery of a projection optical system of a charged particle beam transfer device according to an embodiment of the present invention.

FIG. 2 is an enlarged view showing the vicinity of a contrast opening of the charged particle beam transfer apparatus of FIG. 1, wherein (A) is a sectional view and (B).
Is a bottom view.

FIG. 3 is a diagram illustrating an example of a configuration of an imaging relationship and a control system in the entire optical system of the electron beam projection exposure apparatus of the division transfer system.

FIG. 4 shows a flow of manufacturing micro devices (semiconductor chips such as ICs and LSIs, liquid crystal panels, CCDs, thin-film magnetic heads, micromachines, etc.).

[Explanation of symbols]

12 Reticle-side projection lens 13 Deflector 14 Wafer-side projection lens 17 Wafer stage 18 Contrast opening 25 Liner tube 26 Reticle-side liner tube 27 Wafer-side liner tube 28 Ferrite stack 31 Casing 33, 36 Vacuum piping 35 Sputter ion pump 34, 37 Valve 38 Oxygen Radical Generator 39 High Voltage Power Supply 41 Opening Plate 42 Opening on Optical Axis 43 Contrast Opening Plate 45 Slit Opening

Claims (8)

[Claims] An illumination optical system for illuminating a reticle having a pattern to be transferred onto a sensitive substrate with a charged particle beam, a projection optical system for reducing and projecting a charged particle beam passing through the reticle onto a sensitive substrate, and What is claimed is: 1. A charged particle beam transfer apparatus comprising: a liner tube defining a charged particle beam path of an optical system; wherein the projection optical system includes a two-stage projection lens; A charged particle transfer device provided with an exhaust port of an exhaust pipe connected to the apparatus. 2. An illumination optical system for illuminating a reticle having a pattern to be transferred onto a sensitive substrate with a charged particle beam, a projection optical system for reducing and projecting a charged particle beam passing through the reticle onto the sensitive substrate, and What is claimed is: 1. A charged particle beam transfer apparatus comprising: a liner tube defining a charged particle beam path of an optical system; said projection optical system includes a two-stage projection lens; One end of a pipe for supplying an active gas for cleaning the charged particle beam passage in the inside is open, and the other end of the pipe is connected to a device for generating the active gas through a valve. Characterized charged particle beam transfer device. 3. An illumination optical system for illuminating a reticle having a pattern to be transferred onto a sensitive substrate with a charged particle beam, a projection optical system for reducing and projecting a charged particle beam passing through the reticle onto a sensitive substrate, and What is claimed is: 1. A charged particle beam transfer apparatus comprising: a liner tube defining a charged particle beam path of an optical system; wherein the projection optical system includes a two-stage projection lens; An exhaust pipe connected to is connected via a valve.The liner tube further has one end of a pipe for supplying an active gas for cleaning a charged particle beam passage in the projection lens. A charged particle beam transfer device, wherein a device for generating the active gas is connected to the other end of the pipe via a valve. 4. A charged particle beam transfer apparatus including an optical column for housing an optical system from an energy ray light source to a sample; a wafer chamber for housing a sensitive substrate (wafer); and a transfer to the sensitive substrate. A reticle chamber for accommodating a pattern original (reticle) is provided, and a liner tube serving as a charged particle beam path of the optical lens barrel is formed between the wafer chamber and the reticle chamber. And means for introducing oxygen or oxygen radicals, and means for preventing the introduced oxygen or oxygen radicals from flowing into the wafer chamber or the reticle chamber.
The charged particle beam transfer device according to the above. 5. The charged particle beam transfer apparatus according to claim 1, wherein a contrast opening is arranged in the liner tube. 6. The charged particle beam transfer apparatus according to claim 5, wherein an exhaust route for increasing a vacuum conductance in an optical axis direction is formed in said contrast aperture. 7. An illumination optical system for illuminating a reticle having a pattern to be transferred onto a sensitive substrate with a charged particle beam, a projection optical system for reducing and projecting a charged particle beam passing through the reticle onto a sensitive substrate, and A method for cleaning a charged particle beam transfer apparatus including a liner tube defining a charged particle beam path of an optical system, comprising: supplying an active gas to a liner tube between two projection lenses of the projection optical system; A method for cleaning a charged particle beam transfer device, comprising cleaning a charged particle beam path in a projection lens. 8. A lithographic apparatus, wherein at least one layer of lithography is performed by using the charged particle beam transfer apparatus according to claim 1 or the charged particle beam transfer apparatus cleaned by the cleaning method according to claim 7. Device manufacturing method.