JPH11204400A - Electron beam lithography system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove contaminant attracted or attached to an induction substrate surface during a process until introduction, storage and carrying, by providing an ion generating means which generates ion to be cast on an induction substrate inside a chamber. SOLUTION: An ion generating device is constituted of a mass flow controller 8 and a filament 10, and the mass flow controller 8 and the filament 10 are constituted circularly not to disturb irradiation of electron beam. Inert gas which is ionized is introduced from a gas introduction tube 8a and a flow rate of the gas is adjusted by a mass flow controller 8 and is led out of a gas lead- out hole 8b. The gas is ionized by thermion generated from the filament 10. The ionized gas falls on a surface of an induction substrate 5 and removes contaminant attaching to a surface of the induction substrate 5 and removes contamination attached in electon beam lithography treatment. Furthermore, storage of electric charge is removed by casting ion whose polarity is opposite to that of electron stored locally.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for drawing a fine pattern on a sensitive substrate (wafer, mask or the like) using an electron beam. Note that "drawing" in the present invention includes transfer of a pattern formed on a mask (reticle).

[0002]

2. Description of the Related Art An electron beam lithography apparatus is a vacuum vessel (chamber).
In this apparatus, an electron beam is imaged at an arbitrary position on a sensitive substrate by an electron beam optical system including a lens and a deflector, and a pattern is formed (exposed) on the sensitive substrate coated with a resist. . The pressure in the vacuum vessel is sufficiently low so that there is no problem in the straightness of the electron beam and maintenance. Also,
The resist to be irradiated with the electron beam is an organic substance and an insulating substance.

A process prior to the process of introducing a sensitive substrate into such a drawing apparatus is usually performed in a clean room but in the atmosphere. An electron beam drawing process is performed on such a sensitive substrate surface.

[0004]

In a conventional electron beam lithography apparatus, unlike a solid clean surface in a vacuum, various adsorbing substances and various adsorbed substances are present on the surface of a sensitive substrate (resist surface) which has been treated in the air in a previous step. Contaminants are present. When an electron beam is irradiated on the surface of the resist thus contaminated,
Even if the amount of electron beam irradiation per unit area is kept constant, there is a problem in that the photosensitive state of the resist varies, and depending on the substance adhered to the surface, electron beam scattering or the like is generated, which affects drawing pattern accuracy.

[0005] The atmosphere in the electron beam lithography system contains organic substances, and when the electron beam passes through the atmosphere and reaches the solid surface, the solid surface mainly contains carbon (C). Contamination adheres. The adhesion of the contaminants adversely affects subsequent processes such as development, etching, and ashing. An object of the present invention is to solve such a problem.

[0006]

According to a first aspect of the present invention, there is provided an electron beam lithography apparatus having a chamber provided with an exposure unit for exposing a sensitive substrate with an electron beam. An electron beam lithography apparatus (claim 1) is provided with ion generating means for generating ions for irradiating a sensitive substrate.

[0007] A second means for solving the above-mentioned problems is as follows.
The first means is characterized in that it comprises an accelerating part and a deflecting part for accelerating and deflecting the ions generated by the ion generating means (claim 2). A third means for solving the above-mentioned problem is the first or second means, wherein a region immediately before or immediately after an electron beam irradiation region on the surface of the sensitive substrate is configured to be capable of ion irradiation. (Claim 3).

[0008] A fourth means for solving the above problem is as follows.
In an electron beam lithography apparatus having a chamber provided with an exposure unit for exposing a sensitive substrate with an electron beam, a subchamber separated from the chamber by a door is provided, and ions are irradiated to the sensitive substrate in the subchamber. An electron beam lithography apparatus (claim 4) characterized in that the ion irradiation means is provided.

A fifth means for solving the above problem is as follows.
The fourth means is characterized by comprising an accelerating part and a deflecting part for accelerating and deflecting the ions generated by the ion generating means (Claim 5). (Function) According to the present invention, the ion irradiation on the sensitive substrate before the electron beam drawing processing can remove the contaminant adsorbed or adhered to the surface of the sensitive substrate by pre-process up to introduction, storage, transportation and the like. Variations in the photosensitive state of the resist and a decrease in drawing accuracy that have occurred can be prevented. Further, by removing the contamination attached by the electron beam lithography process, the influence on the subsequent steps can be removed. Such contamination can be better removed by accelerating and irradiating the ions. Such a process can be performed almost simultaneously with the electron beam drawing process, and in that case, the throughput is not reduced. In addition, since the accumulation of charges on the surface of the sensitive substrate can be removed by ion irradiation, a highly accurate electron beam drawing process can be performed by simultaneously performing the ion irradiation process and the electron beam drawing process. Further, the above-described ion irradiation can be performed in different chambers before and after the electron beam drawing processing.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a view schematically showing a configuration example of a general electron beam lithography apparatus, and FIG. 2 is a diagram showing characteristic portions of the electron beam lithography apparatus according to the embodiment of the present invention. FIG. 4 shows a diagram schematically represented. 1 includes an electron gun 1, an electron lens (electrostatic lens or electromagnetic lens) 2a to 2c, apertures 3a and 3b, an electron beam detector 4, and a stage 6 disposed in a vacuum vessel (chamber) 19. , Deflector 9
And a control unit 27 for irradiating the wafer (sensitive substrate) 5 placed on the stage with an electron beam to expose the resist formed on the wafer 5 to light. Although a direct drawing type electron beam lithography apparatus having a simple configuration has been described as an example so as not to complicate the description, the present invention is directed to a cell projection type and a division transfer type (for example, Japanese Patent Application Laid-Open No. 8-64522). The present invention can be applied to various types of electron beam lithography apparatuses.

FIG. 2 is a diagram in which an ion generator is introduced into a portion indicated by a broken line A in FIG. 1, FIG. 2 (a) shows a side view of the ion generator, and FIG. 2 (b) shows a top view. Show. The ion generator includes a mass flow controller 8 and a filament 10. As shown in FIG. 2B, the mass flow controller 8 and the filament 10 are formed in an annular shape so as not to hinder electron beam irradiation. Gas to be ionized, for example, Ar or X
An inert gas such as e is introduced, and the flow rate of the introduced gas is adjusted by the mass flow controller 8, and the gas is led out from the gas outlet hole 8b. The gas led out from the lead-out hole 8b is ionized by thermionic electrons generated from the filament 10, and the ionized gas falls on the surface of the sensitive substrate 5. It was possible to remove contaminants adhering to the surface of the sensitive substrate 5 by such ion irradiation and to remove contaminants adhering by electron beam lithography.

When electron beam lithography is performed (especially in the case of low-acceleration exposure), local charge accumulation (charge-up) occurs on the surface of the semiconductor substrate, which may adversely affect exposure accuracy. Even in such a case, the present invention is effective, and it becomes possible to eliminate the accumulation of electric charge by irradiating ions having the polarity opposite to that of the locally accumulated electrons. The ion irradiation process on the sensitive substrate 5 is performed by the irradiation of the sensitive substrate 5 with the electron beam 7.
May be performed at the same time as the irradiation, or before and after the electron beam irradiation treatment.

FIG. 3 shows a modification of the ion generator shown in FIG. 2. The gas introduction and the basic structure are the same as those of the apparatus shown in FIG. 2, but an accelerating electrode 2 for accelerating ions is used.
8. Deflection electrode 14 and lens 2 for deflecting ions
9 is provided. Gas inlet tube 12 and filament 13
2 can be used, but the ion generator of FIG. 3 can be arranged at a position away from the electron beam 7 as compared with the apparatus of FIG. do not have to. The deflection electrode 14, the acceleration electrode 28, and the lens 29 are controlled by the control unit 27, and the ions can be two-dimensionally scanned on the wafer 5 by controlling the voltage applied to the deflection electrode 14. Also, raster scanning can be performed by applying a voltage to the deflection electrode at a specific frequency. For example, if the voltage applied to the acceleration electrode 28 is about several KV, the effect of removing contamination can be improved. Further, by providing the lens 29, generated ions can be converged or expanded to a desired region size. The ion acceleration, deflection, and lens action are not limited to the present embodiment, and a well-known technique (for example, a technique relating to an ion exposure apparatus) can be used.

FIG. 4 shows a region immediately before electron beam irradiation (FIG. 4).
(B)) or a region immediately after (FIG. 4 (a)) is irradiated with ions. In the case of the apparatus having the configuration shown in FIG. 3, the voltage applied to the deflection electrode 14 and the voltage applied to the electron beam deflector 9 are synchronized. That is, assuming that the arrow 18 is the electron beam deflecting direction, the ion irradiation area 16 is configured to scan the wafer at a certain distance from the electron beam exposure area 17 so as to scan the area immediately after the electron beam irradiation. Ion irradiation can be performed (FIG. 4A). Of course, if the relationship between the electron beam exposure region 17 and the ion irradiation region 16 is reversed, ion irradiation can be performed before electron beam drawing. When electron beam writing is performed by moving the stage without deflecting the electron beam, the order of arrangement of the electron beam exposure area 17 and the ion irradiation area 16 with respect to the moving direction of the stage can be selected. The region immediately before the irradiation and the region immediately after the irradiation can be irradiated with ions. For example, assuming that the direction of the arrow 18 in FIG. 4A is the moving direction of the stage, ion irradiation is performed immediately before electron beam irradiation. In the apparatus shown in FIG. 2, since the ion irradiation area is not specified, it is possible to perform the ion irradiation on both the area immediately before and immediately after the electron beam irradiation. As described above, when the electron beam drawing processing step and the ion irradiation processing step are performed simultaneously, it is possible to prevent a decrease in throughput due to ion irradiation. In the above description, the ion generator is provided in the chamber for irradiating the electron beam. However, as shown in FIG. 5, the ion generator may be provided in the sub-chamber (ion processing chamber) 20.

The vacuum chamber 19 and the sub-chamber 20 are connected via a valve (door) 26.
Inside, a gas introduction chamber 21, a gas introduction tube 22, a filament 23, an acceleration electrode 24, and a wafer 25 are arranged. The ion irradiation on the wafer 25 is the same as described above. The gas introduced from the gas introduction pipe 22 into the gas introduction chamber 21 is ionized by thermionic electrons generated from the filament 23, and the ionized gas is converted by the acceleration electrode 24. The wafer is drawn downward in the figure and irradiated onto the wafer 25.

An ordinary electron beam lithography apparatus often includes a subchamber in addition to a vacuum chamber (chamber) for performing actual electron beam lithography. This is because, by lowering the pressure in the sub-chamber in advance, it is possible to prevent the degree of vacuum in the main chamber from being lowered, thereby improving the throughput. Therefore, this sub-chamber can be used in the apparatus shown in FIG. The cost can be reduced by using the subchamber already provided. For example,
If a valve for loading a wafer is provided in the sub-chamber 20 and a wafer is loaded from the valve, it can be used together with an existing chamber.

In the apparatus shown in FIG. 5, before or after electron beam lithography, ion irradiation can be performed in a sub-chamber different from the electron beam lithography chamber. Above all, ion irradiation can be performed.

[0018]

As described above, according to the present invention, it is possible to remove contaminants on the surface of a semiconductor substrate before performing a process of drawing by an electron beam, thereby preventing variations in the photosensitive state of resist and a decrease in drawing accuracy. In addition, the contamination due to the electron beam drawing process can be removed, and the influence on the subsequent process can be removed. Since this process can be performed almost simultaneously with the electron beam drawing process, there is no effect on the throughput. Further, as secondary effects, it is possible to perform ion irradiation at the same time as electron beam irradiation, and it is possible to eliminate charge-up due to electron beams, and various other effects are obtained.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a configuration of a general electron beam writing apparatus to which the present invention can be applied.

FIG. 2 is an enlarged schematic diagram showing only a characteristic portion of the electron beam writing apparatus according to the embodiment of the present invention.

FIG. 3 is an enlarged schematic diagram showing only a characteristic portion of the electron beam writing apparatus according to the embodiment of the present invention.

FIG. 4 is an enlarged view schematically showing only a characteristic portion of the electron beam writing apparatus according to the embodiment of the present invention.

FIG. 5 is an enlarged view schematically showing only a characteristic portion of the electron beam writing apparatus according to the embodiment of the present invention.

[Explanation of symbols]

 1: electron gun 2a to c: lens system 3a to b: aperture 4: electron beam detector 5: wafer 6: stage 7: electron beam 8: gas introduction tube 8a: gas introduction tube 8b: gas ejection hole 9: deflector 10: Filament 12: Gas introduction tube 13: Filament 14: Ion deflection electrode 15: Ion beam 16: Ion irradiation area 17: Electron beam drawing area 19: Chamber 20: Ion processing chamber (sub-chamber) 21: Gas introduction chamber 22: Gas inlet tube 23: Filament 24: Extraction (acceleration) electrode 25: Wafer (semiconductor substrate) 26: Valve 27: Control unit 28: Ion acceleration electrode

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 21/30 551

Claims (5)

[Claims] 1. An electron beam lithography apparatus having a chamber having an exposure unit for exposing a sensitive substrate with an electron beam, comprising: an ion generating means for generating ions for irradiating the sensitive substrate in the chamber. An electron beam drawing apparatus characterized by being provided. 2. The electron beam lithography apparatus according to claim 1, further comprising: an accelerating section for accelerating and deflecting the ions generated by said ion generating means, and a deflecting section. 3. The electron beam lithography apparatus according to claim 1, wherein an area immediately before or immediately after an electron beam irradiation area on the surface of the sensitive substrate is irradiated with ions. 4. An electron beam lithography apparatus having a chamber provided with an exposure unit for exposing a sensitive substrate with an electron beam, comprising: a subchamber separated from the chamber by a door; An electron beam lithography apparatus comprising an ion generating means for generating ions for irradiating a sensitive substrate. 5. An electron beam lithography apparatus according to claim 4, further comprising: an acceleration section for accelerating and deflecting the ions generated by said ion generation means, and a deflecting section. .