JPS62230022A - X-ray projection exposure device - Google Patents

Abstract

PURPOSE:To form a highly precise pattern by composing the title device out of a diffraction board having a focusing ability to converge an incident X-ray with predetermined inclination on a point on a normal passing the center of its surface, an X-ray absorbing mask formed on said board, and an X-ray imaging element arranged on a focusing point of the diffraction board. CONSTITUTION:After an X-ray emitted from an X-ray source S is incident on a boarde, only the X-ray irradiating a mask M patterned on a mask board K is diffracted by a crystal lattice of the mask board K. Because the crystal lattice is cuved, the Xrays are converged on an X-ray imaging element F. Accordingly, the all diffracted X-rays on the points on the mask surface pass the imaging element effectively. An image of an X-ray mask is formed on a wafer W by the X-ray imaging element F. At that time, because an optical axis A is predetermined to be vertical to a surface of the mask K, the image formed on the wafer is a reduction of the X-ray mask. Then, reduction transfer of a mask pattern becomes possible and a highly precise pattern can be formd.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an X-ray projection exposure apparatus for X-ray lithography and the like.

Technique 11.i at the end of the conventional LSI manufacturing process has generally used a phototransfer method to form a resist pattern. However, the optical transfer method is said to have a limit of 0.5 μm, and due to the influence of Fresnel diffraction and the small depth of focus, the 5M resist method and C
Processing techniques such as the EL method must be used, but the process becomes sloppy, causing a drop in yield, and if it goes beyond the limits of regularity, tQ and j will be reduced. This is it
Electron beam direct writing and X-ray lithography are being considered as alternatives. However, in order to create a direct drawing force type, it is necessary to connect through projects and stages.

There are many pressure points, such as having to perform multiple facials at once. In contrast, X-ray lithography is a transfer process
7 is promising because it is suitable for large-scale production, and since it uses light beams with a wavelength of several IA, the effect of breakage in practical use is negligible. 0.1μ! n
J to the extent! 1 degree is expected.

There are two main methods of X-ray phosphorography. One is the currently used method, in which the distance between the X-ray mask and the wafer is set to ICμ! This is the so-called 10 ximity method, which irradiates the front and back of the mouth with X-rays and transfers the mask pattern. There are 9 exposure methods for transferring.

The present invention relates to the latter projection exposure method, but all conventional methods are transmission masks used in the gloximity method, and the wavelength of the X-rays used in X-rays in the so-called soft X-ray region are easily absorbed by substances, so X-ray transmitting materials such as BN (boron nitride) are used as the substrate for the X-ray mask. A thin film with a diameter of several micrometers that has been shaved off by t1 is used, and an X-ray absorbing film such as Au is coated on top of the interstitial membrane. For this reason, the transmission mask itself is mechanically very fragile and difficult to handle, and it has many problems such as strength, distortion due to heat, flatness, etc., and it is also as complicated as one resin. Therefore, there was a pressure point where proximity devices using transmission masks became expensive and cumbersome. In addition, in terms of function, the conventional 10 ximity method using one transmission mask is a close-up projection method and is not a reduction projection method, so a pattern can only be transferred with the same resolution as that of a transmission mask.

Problems to be Solved by the Invention The present invention solves the problems of X! ! By providing a reflective X-ray mask patterned on an XvA reflective substrate with a light focusing function, we solve the problems of conventional transmissive masks and enable reduced projection, making it easy to create high-precision patterns. The purpose is to make it available.

21 Means for Solving Problems A diffractive substrate is used which has the ability to focus incident X-rays with a predetermined inclination to a point on the normal line passing through the center of the surface, and Xj! is formed on the same substrate. An X-ray projection exposure apparatus was constructed by an absorption mask and an X-ray imaging element placed at the focal point of the diffraction substrate.

E, for fv The present invention is based on an X-ray beam patterned with an X-ray absorbing thin layer 11M on a crystal substrate having a light focusing function in which the diffracted X-ray at the center point of the X-ray mass 2M matches the normal line of the mask surface. It utilizes X-ray diffraction using a reflective mask M, and as shown in the figure, when X-rays are emitted from an X-ray light source S to an X-ray mask,
Only the X-rays emitted to the part of the substrate where there is no X-ray absorbing 3 film M that has been battened on the substrate are absorbed by the crystal lattice C on the mask substrate.
The central X-ray of the diffracted X-ray flux is directed in the normal direction of the diffraction substrate surface, that is, the mask surface is perpendicular to the X-ray flux. In this way, a reduced image of the X-ray mass 2M is formed on the wafer W by the X-ray imaging element F, just as the transmission mask is illuminated from behind with a condenser to form an image of the area of the transmission mask.
It has become possible to obtain highly precise patterns.

An embodiment of the present invention is shown in FIG. In the figure, K is an X-ray diffraction substrate cut obliquely from a curved crystal with a lattice constant d, and an X-ray absorbing film (Au, etc.) is patterned on the surface.
0 is the center point of the mask, C is the lattice plane passing through the 0 point of the original curved crystal, R is the center of curvature, and S is the X-ray source. , N is a line connecting the center point of the mask and the center of curvature of lattice plane C (13T plane normal), F
is a Fresnel zone plate which is an X-ray imaging element placed on the normal line to the center of the diffraction substrate, and W is a wafer that forms an image of the mask.

As an example, a 1/5 reduction projection y exposure X-ray optical system is constructed. Ge single crystal is used as the material of the curved crystal, and its (111) plane is the diffraction grating plane, X-ray wavelength λ = 5.4
06A, t3 constant d=3°25A, radius of curvature of crystal lattice plane at center point 0 of substrate surface is 499.2a+a,
When the inclination between the substrate surface and the lattice plane is 33.7°, the normal to the center of the substrate surface satisfies Bragg's condition with respect to the (111) plane of Ge. The curved crystal size is 50m + ax50mm,
Formation of crystals from the surface of the crystal [9. The distance to the element (FZP) is 60
0 north, the distance from the center point of the mask surface to the light source is 277.
Let us consider the case of binding 2+++a+.

In this configuration, XrA emitted from the XvA source S
After being incident on the substrate, only the X-rays irradiated onto the mask M that is battened on the mask substrate, that is, the part where there is no X-ray absorbing thin film, are diffracted by the crystal lattice of the mask substrate, causing the crystal lattice to curve. Therefore, the light is focused on the X-ray imaging element F. Therefore, all the diffracted X-rays at each point on the mask surface effectively pass through the coupling element. The image of the X-ray mask is focused onto the wafer W by the X-ray coupling element F. At this time, since the optical axis is set perpendicular to the surface of the mask M, the image formed on the wafer is a reduction of the X-ray mask.

G. Effects According to the present invention, it is possible to reduce and transfer a mask pattern using an X-ray projection exposure apparatus that uses a reflective X-ray mask with a strong and unbreakable X-ray diffraction substrate as a support. , easily high t? It became possible to produce dense patterns.

[Brief explanation of drawings]

The figure is a configuration diagram of a practical example of the present invention.

Claims (1)

[Claims] A diffractive substrate that has the ability to focus incident X-rays with a predetermined inclination to a point on a normal line passing through the center of the surface, an X-ray absorption mask formed on the substrate, and a focusing point of the diffractive substrate. 1. An X-ray projection exposure apparatus comprising an X-ray imaging element arranged in an X-ray projection exposure apparatus.