JP2000049080A - Charged particle beam exposure system - Google Patents

Abstract

(57) [Problem] To provide a charged particle beam exposure apparatus capable of preventing foreign matter from adhering to an exposure mask. SOLUTION: An electron beam transmitting film 5 is arranged on both sides of a surface irradiated with an electron beam 3 and a surface on an imaging electron lens system 4 side, or only one surface. Since the electron beam transmitting film 5 has a property of transmitting the electron beam 3 but not passing foreign matter such as dust, the foreign matter does not adhere to the mask 1 but adheres to the electron beam transmitting film 5. . Even if foreign matter adheres to the electron beam transmitting film surface, its position is slightly away from the mask surface,
If it is out of focus and of normal size, it will not hinder the transfer of the mask pattern to a sensitive substrate such as a wafer. In addition, when large foreign matter adheres and hinders the transfer of the mask pattern to the sensitive substrate, only the film needs to be replaced, and there is no need to realign the exposure apparatus. Is not taken.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charged particle exposure apparatus which prevents foreign substances such as dust from adhering to a mask used for exposure transfer.

[0002]

2. Description of the Related Art In a semiconductor device manufacturing apparatus, a charged particle exposure apparatus using charged particles represented by an electron beam has been developed as an alternative to the optical reduction projection exposure technique in order to create a finer circuit pattern. Is being done.

Conventionally, in an exposure technique using an electron beam, a method of drawing a circuit pattern by narrowing down the electron beam and scanning a semiconductor substrate coated with a resist sensitive to the electron beam has been used. . However, in this method, since a pattern is drawn with one electron beam, it takes time to create one chip, and compared with a light reduction projection exposure apparatus that collectively transfers a circuit pattern onto a substrate. However, there is a problem that productivity (throughput) is low.

Therefore, at present, similarly to the light reduction projection exposure technology, a technology for irradiating an electron beam on a mask on which a circuit pattern is formed and reducing and projecting the electron beam passing through the mask onto a semiconductor substrate has been developed. ing. The reduction projection method requires a mask on which a circuit pattern is formed. However, since the circuit pattern can be exposed on the substrate at one time, the productivity is greatly improved as compared with the one-stroke method using an electron beam.

A mask for electron beam exposure has a thickness of several μm.
A film obtained by extracting the shape of a circuit pattern from a thin film of m is used. As the material of the thin film, Si without any doping, Si doped with boron or the like is used.

[0006]

In an electron beam exposure apparatus for performing reduction projection, an electron beam is blocked at a portion where a film of a mask exists, an electron beam is passed at a portion where the film is removed, and the passed electron beam is blocked. An image is formed on a substrate by the action of an imaging electron lens, and a circuit pattern is transferred.

Therefore, if there is a foreign substance having a property of not transmitting an electron beam in a portion where the film of the mask is removed,
There is a problem that the electron beam is blocked by the foreign matter and the circuit pattern is not correctly transferred onto the substrate. Such a problem also occurs in an exposure apparatus using charged particles other than an electron beam.

When foreign matter adheres to the mask, it is necessary to remove the mask from the exposure apparatus and perform cleaning or replace it with a new one. When the mask is removed from the exposure apparatus, the alignment of the exposure apparatus needs to be performed again, and there is a problem that it takes a long time in the production process.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and is directed to a charged particle beam exposure apparatus utilizing charged particles represented by an electron beam, wherein foreign matter adheres to an exposure mask. It is an object of the present invention to provide a device capable of preventing the above.

[0010]

A first means for solving the above-mentioned problems is that a film which transmits a charged particle beam and does not allow a foreign substance such as dust to pass through is provided on a mask installation portion when a mask is installed. A charged particle beam exposure apparatus provided near one or both surfaces of the mask (claim 1)
It is.

In this means, a film is provided on the mask installation portion, and when the mask is installed in the charged particle exposure apparatus, this film comes close to one or both surfaces of the mask.
Since this film transmits the charged particle beam, it does not hinder the projection exposure. Since this film does not transmit foreign substances such as dust, it is possible to prevent the foreign substances from adhering to the mask surface.

[0012] Even if foreign matter adheres to the film surface, the position is slightly away from the mask surface, so that it is out of focus. It does not hinder the transfer of the mask pattern to the mask. In addition, when large foreign matter adheres and hinders transfer of the mask pattern to the sensitive substrate, only the film needs to be replaced. In this case, it is not necessary to realign the exposure apparatus, so that the production process is not required. No extra time is required. In the present invention, the mask includes an equivalent such as a reticle.

[0013] A second means for solving the above-mentioned problems is as follows.
The first means, wherein the thin film is made of Si ₃ N ₄ (Claim 2).

If Si ₃ N ₄ is about 50 nm thick, a structurally strong and stable film can be easily formed.
Further, since the mean free path when an electron beam of 100 KeV is incident is about 80 nm, if the thickness is about 100 nm, it can be used as a film that transmits a high proportion of electron beams.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating a main part of a mask installation unit according to an embodiment of the present invention. In FIG. 1, 1 is a mask, 2 is an electron beam source, 3 is an electron beam, 4 is an imaging electron lens system, 5 is an electron beam transmitting film, and 6 is a spacer.

An electron beam 3 generated by an electron beam source 2 irradiates a mask 1 via an illumination electron lens system (not shown), and a circuit pattern formed on the mask 1 is formed by an imaging electron lens system 4. Transfer onto wafer (not shown).

The electron beam is transmitted through both the surface of the mask 1 on which the electron beam 3 is irradiated (hereinafter, referred to as the front surface of the mask) and the surface on the imaging electron lens system 4 side (hereinafter, referred to as the back surface of the mask). A film having properties (hereinafter referred to as an electron beam transmitting film) 5 is provided. The electron beam transmitting film 5 may be provided on only one of the front surface and the back surface of the mask. In order to prevent foreign matter from entering through a gap between the mask 1 and the electron beam transmitting film 5, the mask 1
It is preferable that the distance between the electron beam transmitting film 5 and the electron beam transmitting film 5 be as close as possible. Further, a spacer 6 may be provided to fill a gap between the electron beam transmitting film 5 and the mask 1.

Since the electron beam transmitting film 5 has the property of transmitting the electron beam 3 but not passing foreign matter such as dust, the foreign material does not adhere to the mask but adheres to the electron beam transmitting film 5. become. Examples of the foreign matter include metal particles emitted from a part of a machine for moving a wafer, oil mixed in from an exhaust system for creating a vacuum, and carbon generated by irradiating the oil with an electron beam.

In the present embodiment, the electron beam transmitting film 5
, A Si ₃ N ₄ film is used. In addition to Si ₃ N ₄ , for example, Be, diamond, A1, Si, SiO ₂ , S
A substance having a small number of atoms, such as iC or Al ₂ O ₃ , can be used as the electron beam transmitting film 5.

[0020]

EXAMPLE A method of forming a Si ₃ N ₄ film used in an example of the present invention will be described below with reference to FIG. In FIG. 2, 7 is a Si substrate, 8 is a Si ₃ N ₄ film, 9 is a resist, 10
Denotes an electron beam transmitting portion, and 11 denotes a mask.

First, Si ₃ N ₄ was deposited on both surfaces of a Si substrate 7 using a chemical vapor method to form a Si ₃ N ₄ film 8 (a). Thereafter, a resist 9 was applied to one surface of the Si substrate 7, and only the area required for the electron beam transmitting portion 10 was baked on the surface on which the resist 9 was applied using photolithography (b).

Subsequently, the resist is developed and printed.
After removing the resist in the area, the Si
_ThreeN_FourThe film 8 was removed by dry etching (c).
Finally, the Si substrate 7 is anisotropically etched with a KOH solution.
did. At this time, Si_ThreeN_FourParts are not etched
Therefore, the area necessary for the electron beam transmitting section 10 is made of Si _Three
N_FourOnly membrane 8 remained. (D) In this way, a thickness of 100
nm Si_ThreeN_FourA membrane was made. This Si_ThreeN_FourDiameter 1 on membrane
Even if Al particles of about 0 μm are sprinkled, the film may break.
It functioned as a dustproof film.

According to the above method, the Si substrate 7 remains as a support of the Si ₃ N ₄ film around the electron beam transmitting portion.
The portion of the Si substrate 7 is used as a spacer for filling a gap between the mask and the electron beam transmitting film, so that entry of foreign matter from the gap can be prevented.

[0024]

As described above, according to the present invention, when a mask is installed on a mask installation portion, a film that transmits a charged particle beam and does not allow foreign matter such as dust to pass through the mask installation portion. Since it is provided close to both sides,
Foreign matter can be prevented from adhering to the mask. As a result, it is not necessary to replace the mask due to the adhesion of the foreign matter, and it is not necessary to perform realignment with the replacement of the mask. In addition, it is possible to prevent the occurrence of defective products due to the attachment of foreign matter to the mask.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a main part of a mask installation unit according to an embodiment of the present invention.

FIG. 2 is a diagram showing an outline of a method of forming a Si ₃ N ₄ film used in an example of the present invention.

[Explanation of symbols]

1 ... Mask 2 ... electron beam source 3 ... electron beam 4 ... imaging electron lens system 5 ... electron beam transmitting film 6 ... spacer 7 ... Si substrate 8 ... Si ₃ N ₄ film 9 ... resist 10 ... electron beam transmitting portions 11 ... mask

Claims (2)

[Claims] 1. A mask installation part, wherein a film that transmits a charged particle beam and does not allow foreign substances such as dust to pass therethrough is provided so as to be close to one side or both sides of the mask when the mask is installed. Charged particle beam exposure apparatus. 2. The charged particle beam exposure apparatus according to claim 1, wherein said film is made of Si ₃ N ₄ .