JP3258104B2 - Charged beam irradiation method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for irradiating a charged beam used in manufacturing a semiconductor device, and more particularly to a method and an apparatus for irradiating a charged beam capable of removing contaminants deposited by electron irradiation.

[0002]

2. Description of the Related Art In a charged beam irradiation apparatus, there is a problem that hydrocarbon-based deposits adhere to parts and the like in the apparatus due to irradiation of electrons. This deposit adheres not only to an electron beam exposure apparatus and various analyzers using an electron beam but also to an ion beam irradiation apparatus due to secondary electrons or the like generated upon ion beam irradiation.

[0003] Since hydrocarbon deposits cause charge-up, they have been a major problem. For example, in an electron beam exposure apparatus, charge-up is directly related to exposure accuracy because it causes beam drift.

[0004] Conventionally, at the time when a drift that causes a problem occurs, the vacuum vessel is opened to the atmosphere, the lens barrel is disassembled, and replaced with a clean part. However, since the lens barrel of the electron beam exposure apparatus is extremely complicated and assembled with high precision, it takes a great deal of labor and time to replace the components making up the lens barrel.

As a result, there has been a problem that the time during which the operation is interrupted is increased, and the efficiency of use of the apparatus is greatly reduced.

As a method and apparatus for solving the above problems, a reactive gas selected to react with the sediment to form a volatile compound is introduced into a vacuum vessel and the volatile compound is removed from the vacuum vessel. There is a method and an apparatus for removing (see JP-A-60-77340 and JP-A-4-94524).

However, in these methods and apparatuses, since the entire area inside the vacuum vessel is filled with the reactive gas, in order to completely remove the thickest deposited area, even parts that do not need to be cleaned are converted to the reactive gas for a long time. The result is a simplification.

In the case of an electron beam exposure apparatus or the like, contamination occurs intensively near the beam trajectory, and such a method is useless. On the other hand, since there are components and lead wires of various materials in the vacuum vessel, if a reactive gas is introduced more than necessary, there is a defect that the surface is oxidized.

Another drawback is that even if cleaning is performed by supplying a reactive gas into a narrow gap in the charged beam irradiation apparatus, the reactive gas is consumed on the way or collides with a wall to be deactivated. . For this reason, it has been difficult to clean the inside of the electrostatic deflection lens and the inside of a cylindrical component such as an elongated sleeve.

[0010]

In the conventional charged beam irradiation method and apparatus, since the entire area inside the vacuum vessel is filled with the reactive gas, even parts that do not require cleaning are exposed to the reactive gas, and the surface is oxidized. However, there is a problem that it is difficult to clean a narrow gap.

The present invention has been made in view of the above circumstances, and it is possible to remove only contaminants adhering to a vacuum vessel without damaging other parts that do not require cleaning. It is an object of the present invention to provide a method and apparatus for irradiating a charged beam that can be cleaned.

[0012]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a charged beam irradiation method according to the present invention comprises a component of the barrel provided in a barrel of the charged beam irradiation apparatus or a component of the barrel. A cleaning gas that reacts with the contaminant to form a volatile compound is sprayed locally onto the contaminant adhered to the inner wall of the vacuum vessel at a pressure higher than the internal pressure of the vacuum vessel to remove the contaminant. It is characterized by including the step of performing.

[0013] Alternatively, the charged beam irradiation method of the present invention comprises:
Reacts with contaminants to form a volatile compound in a region where the contaminants adhere to the components of the lens tube provided in the column of the charged beam irradiation apparatus or the inner wall of the vacuum vessel of the column. The method is characterized in that the method includes a step of spraying a cleaning gas simultaneously with the irradiation of the charged beam at a pressure higher than the pressure in the vacuum vessel and simultaneously preventing the contaminant from adhering.

The charged beam irradiation apparatus of the present invention is provided outside the vacuum vessel of the lens barrel, and is connected to a gas introduction means for introducing a cleaning gas into the vacuum vessel, and is connected to the gas introduction means. A cleaning gas introduced from the gas introduction means into the vacuum vessel is locally sprayed onto components inside the vacuum vessel or contaminants attached to the inner wall of the vacuum vessel at a pressure higher than the pressure inside the vacuum vessel. A nozzle having a possible opening.

In the charged beam irradiation method and apparatus according to the present invention, a cleaning chamber is provided outside the vacuum vessel and separable from the vacuum vessel, and contaminated components are transferred to the cleaning chamber while maintaining the degree of vacuum. Then, after cleaning in the cleaning chamber, the components may be transported to the vacuum container again.

The opening of the nozzle is preferably directed or inserted into the narrow gap to be cleaned. Ideally, the outside is metal and the inside is nonmetal.

[0017]

In the present invention, the cleaning gas is locally sprayed to the contaminated portion by the nozzle in the vacuum vessel of the charged beam irradiation device, so that the contaminants are efficiently removed.
In addition, portions not requiring cleaning are hardly exposed to the reactive gas.

Further, according to the present invention, the tip of the nozzle is inserted into a narrow gap such as an electrostatic deflecting lens or a sleeve of an optical system, and the active species of the cleaning gas is sufficiently supplied to the back without deactivating. .

Further, according to the present invention, an active species generated by electric discharge is used as a cleaning gas, and a nozzle having a metal on the outside and a non-metal on the inside is used to deactivate the active species while preventing charge-up by an electron beam. Without cleaning, the cleaning gas can be effectively cleaned with a small flow rate of the cleaning gas.

Further, if a cleaning chamber which can be separated from the vacuum container is provided, the cleaning chamber provided outside the vacuum container while maintaining the degree of vacuum in the vacuum container of the charged beam irradiation device while the contaminated parts are provided. The cleaning chamber is blown into the cleaning chamber after the cleaning gas is blown in the cleaning chamber after separating the vacuum chamber and the cleaning chamber from each other, so that parts other than the contaminated parts can be cleaned without being exposed to the reactive gas at all.

[0021]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a charged beam irradiation apparatus according to an embodiment of the present invention;

FIG. 1 is a sectional view of a part of a lens barrel for describing a first embodiment of a charged beam irradiation method and apparatus according to the present invention.

In the first embodiment, a method for preventing contamination of the shaping aperture which is a component of the lens barrel will be described.

As shown in FIG. 1, a beam focusing electromagnetic coil 2 and a shaping aperture 3 which are components of the lens barrel are mounted in a lens barrel vacuum vessel 1. A cleaning gas introduction system 4 is provided outside the vacuum vessel 1, and the cleaning gas introduction system 4 is provided with a vacuum vessel 1 from the cleaning gas introduction system 4.
Is connected to a nozzle 5 for introducing a cleaning gas into the inside.

The nozzle 5 has an opening 7 that can be locally sprayed on the electron beam irradiation area 6 on the shaping aperture 3. Reference numeral 8 denotes an electron beam to be irradiated.

First, at the same time as the beam irradiation, the O ₂ gas is activated by high-frequency discharge in the cleaning gas introduction system 4, and the resulting atomic oxygen O ^* is introduced by the nozzle 5, and the shaping aperture 3 where deposits are liable to adhere. Was sprayed onto the electron beam irradiation area 6 of the above.

As a result of the experiment, the gas pressure on the shaping aperture 3 was reduced to about 10 ⁻³ Torr by spraying 0.5 sccm of the cleaning gas from the nozzle 5, but immediately diffused, and the gas was diffused to another location in the vacuum vessel 1. Vacuum degree is 10 ^-6 To
It was kept at the rr level, and no change was observed in the electron beam accuracy on the sample not shown.

In the conventional method without using the nozzle 5, that is, when the cleaning gas is introduced from the vacuum vessel wall, the flow rate of the cleaning gas is set to 5 seconds in order to obtain the same level of pollution prevention effect.
It is necessary to fill the vacuum vessel 1 with a pressure of 10 ⁻³ Torr by increasing the pressure to 10 cm ^-3 . Particularly, when the electron beam trajectory in the space filled with the cleaning gas is long, it affects the convergence of the electron beam, which is not desirable.

By performing exposure as in the first embodiment, no deposits were left on the shaping aperture 3 at all.

FIG. 2 is a sectional view of a part of a vacuum vessel for explaining a second embodiment of the charged beam irradiation method and apparatus according to the present invention. 2, the same parts as those in FIG. 1 are denoted by the same reference numerals.

In the second embodiment, a method for cleaning the inside of the electrostatic deflection lens of the optical system will be described.

As shown in FIG. 2, an electromagnetic coil 2 for converging a beam, which is a component of the lens barrel, is mounted in a vacuum vessel 1 of the lens barrel.
Is arranged.

A driving device 10 is provided outside the vacuum vessel 1, and the cleaning device 4 is connected to the driving device 10. Further, the driving device 10 includes a cleaning gas introduction system 4.
Further, a nozzle 5 for introducing a cleaning gas into the vacuum vessel 1 via a driving device 10 is connected.

The nozzle 5 has an opening 7 that can be locally sprayed from the opening of the deflecting lens 9 into a narrow inside.

The nozzle 5 is positioned by the driving device 10 so that the opening 7 is opposed to the opening of the deflecting lens 9 at the time of cleaning (a in the figure), and is sufficiently separated from the trajectory of the electron beam at the time of electron beam irradiation. Moved to position b. The evacuation was performed in the downward direction. In this embodiment, reference numeral 11 denotes a wide range of contaminants due to reflected electrons. In the present embodiment, the nozzle 5 is set at the standby position b during operation of the electron beam exposure apparatus, and the amount of beam drift due to the deposits becomes an allowable amount. When approaching, the electron beam irradiation is stopped, and the driving device 1
By 0, the nozzle 5 was moved to the cleaning position a.

Next, the O ₂ and CF ₄ gases are activated by high-frequency discharge in the cleaning gas introduction system 4, and the resulting O ^* and F ^* are discharged from the nozzle 5 through the nozzle 5 to the upper surface of the deflecting lens 9 on which the deposit has adhered. And sprayed on the inner wall.

Here, FIG. 3 shows the distribution of the resist ashing rate inside the elongated pipe having an inner diameter of 4 mm. The horizontal axis represents the depth from the pipe tip, and the vertical axis represents the resist ashing rate inside the pipe.

A is a pipe placed in an atmosphere in which O ^* and F ^* of the cleaning gas are uniformly filled in a vacuum vessel;
b shows the case where a nozzle having an inner diameter of 7 mm was placed at a position 2 mm above the end of the pipe and gas was sprayed. However, the flow rate of the gas was constant in each case.

When the nozzle 5 is not used, the incineration speed is low as a whole, and decreases with the depth inside the pipe. However, when the nozzle 5 is used, the incineration speed is extremely high, and A sufficient incineration rate is maintained to the back.

As described above, in the conventional method, since the supply amount of the active species decreases as the distance from the opening at the tip of the inside of an elongated component such as the deflection lens 9 and the sleeve decreases, the above-described resist ashing occurs. The rate of sediment removal was slow, as was the rate, and in some cases was not removed at all.

As in the second embodiment, if the nozzle 5 is used, a large amount of cleaning gas can be supplied to a contaminated site at a locally high pressure having a directivity.
In addition, the active species can be supplied to the inside of the elongated shape with almost no influence on other parts.

FIG. 4 is a cross-sectional view for explaining a third embodiment of the charged beam irradiation method and apparatus according to the present invention.

In the first and second embodiments, the method for cleaning the parts inside the vacuum vessel has been described. However, in the third embodiment, the method for cleaning the parts in the cleaning chamber provided outside the vacuum vessel is described. Is shown.

As shown in FIG. 4, a cleaning chamber 12 is provided outside the lens barrel vacuum vessel 1. The cleaning chamber 12 includes a cleaning gas introduction system 4, a nozzle 5 connected thereto, and a vacuum chamber. It comprises a chamber 13, a separation valve 14 for isolating the vacuum chamber 13 from the vacuum vessel 1, an exhaust system 15, and a transfer mechanism 16.

The tip of the nozzle 5 connected to the cleaning gas introduction system 4 is inserted into the vacuum chamber 13, and the lower part of the vacuum chamber 13 maintains the vacuum chamber 13 in a vacuum or the cleaning supplied from the nozzle 5. An exhaust system 15 for exhausting the utility gas is attached.

The transport mechanism 16 is provided with an aperture holder 17 for transporting the shaping aperture 3 between the vacuum chamber 13 and the vacuum vessel 1 as a lens barrel. The shaping aperture 3 is fixed to the aperture holder 17 and is conveyed between the vacuum chamber 13 and the vacuum vessel 1 while maintaining a vacuum.

According to the third embodiment, in order to clean the shaping aperture 3, the operation is stopped when cleaning is necessary, and the degree of vacuum in the cleaning chamber 13 is reduced to about 10 ⁻⁶ Torr by the exhaust system 15. After evacuation, the separation valve 14 is opened, and the aperture 3 is transported into the cleaning chamber 13.

Thereafter, the separation valve 14 is closed to completely separate the vacuum chamber 1 and the cleaning chamber 13 from each other.
, A cleaning gas is introduced, and the nozzle 5 sprays the gas onto the aperture 3 to perform cleaning.

After the cleaning, the cleaning gas is completely exhausted by the exhaust system 15, and then the aperture 3 is returned to the fixed position in the vacuum vessel 1.

According to the third embodiment, the necessary parts can be cleaned without affecting the other parts without maintaining the vacuum of the electron beam exposure apparatus and introducing the reactive gas into the vacuum vessel 1. It can be performed.

The charged beam irradiation method and apparatus of the present invention have been described in the first to third embodiments. However, the shape of the nozzle is not limited to those shown in FIGS. The size, arrangement, number, etc. of the parts can be determined as necessary.

The following is an example of the nozzle shape.

FIG. 5 shows a nozzle shape for more efficiently cleaning the inside of the deflecting lens 9 shown in FIG. An opening 7 is provided over the entire length of the nozzle 5, so that active species can be evenly supplied to the inner wall of the deflecting lens 9.

In this case, the nozzle 5 moves from the standby position b to the cleaning position by moving the nozzle 5 horizontally to the position a and then moving downward so that the nozzle 5 is inserted into the narrow gap from the opening 7 of the deflecting lens 9. Is done.

Further, as shown in FIG. 6, a plurality of openings 7 provided on the circumference of the circular nozzle 5 with respect to the contaminant 11 over a wide range due to the reflected electrons shown in FIG.
Alternatively, the circular opening 7 provided on the circumference of the circular nozzle 5 as shown in FIG. 7 can supply the cleaning gas over a wide range, which is effective.

As shown in the cross-sectional view of FIG. 8, the material of the nozzle 5 is a quartz tube 18 having a nonmetallic inner surface.
Ideally, the outer surface is plated with a thin film 19 of gold. As a result, charge-up of the nozzle 5 due to scattered electrons is prevented.
The active species passing through the inside are hardly deactivated, and the effect can be obtained with a smaller amount of cleaning gas.

[0057]

As described above, according to the present invention, a cleaning gas is locally blown to a contaminant at a high pressure by using a nozzle. The inner wall and the inside of the narrow gap can be cleaned without damaging other parts.

[Brief description of the drawings]

FIG. 1 is a sectional view of a part of a lens barrel for describing a first embodiment of a charged beam irradiation method and apparatus according to the present invention.

FIG. 2 is a sectional view of a part of a lens barrel for describing a second embodiment of a charged beam irradiation method and apparatus according to the present invention.

FIG. 3 is a characteristic diagram showing a resist ashing rate distribution inside an elongated pipe.

FIG. 4 is a sectional view of a part of a lens barrel for describing a third embodiment of a charged beam irradiation method and apparatus according to the present invention.

FIG. 5 is a diagram showing an example of a nozzle shape.

FIG. 6 is a diagram illustrating an example of the shape of a nozzle.

FIG. 7 is a diagram illustrating an example of a nozzle shape.

FIG. 8 is a sectional view for explaining the material of the nozzle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum container of lens barrel 3 Shaping aperture 4 Gas introduction system for cleaning 5 Nozzle 7 Nozzle opening 9 Deflection lens 10 Drive unit 12 Cleaning room 13 Vacuum room 14 Separation valve 15 Exhaust system 16 Transport mechanism 17 Aperture holder

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Haruo Okano 1 Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Prefecture Toshiba R & D Center (56) References JP-A-3-19314 (JP, A) JP-A-63-308856 (JP, A) JP-A-61-59826 (JP, A) JP-A-1-189123 (JP, A) JP-A-64-45123 (JP, A) JP-A-1-293521 (JP) JP-A-3-40418 (JP, A) JP-A-3-76211 (JP, A) JP-A-3-134175 (JP, A) JP-A-56-20268 (JP, U) 53-26112 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/027 H01J 37/16 H01J 37/18 H01J 37/305

Claims (5)

(57) [Claims] 1. A component or lens barrel of lens barrel which is provided in the lens barrel of the charged particle beam irradiation apparatus charged beam irradiation
A cleaning gas containing an active species is applied to the inner wall of the vacuum vessel at a pressure capable of being sprayed from a nozzle having a metal outer surface and a non-metallic inner surface.
A method for locally irradiating a charged beam with a high pressure . 2. The method according to claim 1 , wherein the step of spraying includes the step of :
The charged beam irradiation method according to claim 1, wherein the irradiation is performed simultaneously with the irradiation. 3. A vacuum vessel having a pressure capable of irradiating a charged beam.
When provided outside of the vacuum chamber, the cleaning gas containing active species
The gas introduction means that generates , the outside is metal, the inside is non-metal, the cleaning gas,
On the components inside the vacuum vessel or on the inner wall of the vacuum vessel,
A nozzle capable of locally spraying with a pressure higher than the pressure . 4. A charged particle beam irradiation apparatus according to claim 3, wherein the nonmetal is quartz. 5. A charged particle beam irradiation method according to claim 1 or claim 2 wherein the cleaning gas is comprising atomic oxygen.