JPH0458244A - Reticule and exposing method using this reticule - Google Patents

Abstract

PURPOSE:To accurate transfer dense patterns as well by forming the patterns by holography. CONSTITUTION:A photoresist 7 is applied over the entire surface via an insulating film 6 on a wafer 5 and a hologram 3 is used as a reticule. The photoresist 7 is exposed by using UV light as a laser beam. The light diffracted on the hologram 3 passes a reducing lens 8 and the patterns reduced to 1/5 are superposed on the wafer 5 and are baked. The patterned wafer 5 is immersed in a developer to be developed and the region irradiated with the light is washed away. The unnecessary insulating film 6 is etched away by anisotropic etching using O2. The photoresist 7 is removed by a solvent and the wafer formed with the patterns of the reticule (hologram 3) on the insulating film 6 is produced. The wafer formed with the patterns in such a manner is not formed with the patterns different from the actual patterns even if fine flaws, pinholes, etc., are formed on the reticule, by which the semiconductor device having high reliability is efficiently produced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a reticle suitable for transferring a desired pattern to a photosensitive agent on a support and an exposure method using the reticle.

[Conventional technology]

Conventionally, when transferring a desired pattern onto a desired object (such as a support coated with a photosensitive agent), a method has been used in which exposure is performed through a reticle on which the pattern is drawn.

In particular, as part of the manufacturing process of semiconductor devices, a photoresist (photosensitive agent) is coated on a wafer (support) through an insulating film, and a desired pattern is patterned on a quartz glass. A method using a glass mask (reticle) formed of a Cr thin film is known.

The reticle usually has a pattern drawn on it that is 5 to 10 times the actual size. When the reticle is exposed to light (g-line or i-line) from a mercury lamp using an optical reduction projection exposure device, the pattern drawn on the reticle is reduced by 115 to 1/10 by the projection lens. The photoresist is then projected onto the photoresist on the wafer, thereby patterning the photoresist. The height (focus) of the wafer is automatically measured and controlled using laser light or the like. Furthermore, since mask alignment is automatically performed by recognizing special patterns (register marks) drawn within the reticle pattern, patterning accuracy is high and throughput (the number of wafers processed per unit time) is high.

[Problem to be solved by the invention]

However, in the conventional example, although the pattern drawn on the reticle is accurately and faithfully transferred (burned) onto the photoresist on the wafer, if defects such as scratches and pinholes occur on the reticle, the desired pattern may not match. The problem was that different patterns were transferred to the photoresist on the wafer.

In other words, if a scratch, pinhole, etc. occurs on the reticle, light leaks from that part, exposing parts other than those that should be exposed, and if the photoresist is a positive type, the element may be disconnected in the middle, etc. There was a risk that performance would be impaired.

Further, when the photoresist is negative type, unnecessary elements are formed, which may impair the performance of the elements. As described above, when scratches, pinholes, etc. occur on the reticle, there is a problem that a semiconductor device having desired characteristics cannot be obtained. Furthermore, the scratches that occur on the reticle are minute scratches (0.3μ
Even if the size of the reticle is around 1.5 m), it has a large effect on the semiconductor device, so there is a problem in that a great deal of care must be taken to prevent scratches, pinholes, etc. on the reticle.

In order to solve such problems, the present invention solves the problem of scratches that occur on a reticle when a desired pattern drawn on a reticle is transferred to a photosensitive agent on a support.

The present invention provides a reticle in which a pattern different from the above pattern is not transferred due to pinholes, etc., and an exposure method using the reticle.

[Means to solve the problem]

To achieve this object, the present invention provides a reticle in which a desired pattern is transferred by exposure to a photosensitive agent coated on a support, the pattern being formed by holography. be.

The present invention also provides an exposure method characterized in that a photosensitive agent is patterned using a reticle made of a hologram on which a desired pattern is formed.

[Function] According to the reticle and the exposure method using the same according to the present invention, by patterning a photosensitizer using a reticle consisting of a hologram on which a desired pattern is formed, diffraction or reflection occurs on the hologram used as the reticle. The emitted light overlaps on the photosensitive material, and an actual pattern different from the desired pattern can be transferred (printed).

Therefore, even if scratches, pinholes, etc. occur in the hologram, the edge portions of the pattern are only slightly blurred. With conventional exposure methods, even if minute scratches, pinholes, etc. that cannot be visually determined occur on the reticle, they directly affect pattern reproducibility.
According to the exposure method of the present invention, even if minute scratches, pinholes, etc. that cannot be visually determined occur, they have no effect on the pattern at all. There is no need to take great care in generating such problems, and a pattern different from the desired pattern will not be transferred to the photosensitive agent.

〔Example〕

Next, one embodiment of the present invention will be described based on the drawings.

In this example, hologram 3 was produced using known computer holography (Somitsu Hirai: Fundamentals and Experiments of Holography, published by Kyoritsu Shuppansha, July 20, 1978).

In normal holography, a hologram is created using interference fringes resulting from the synthesis of an object beam that has passed through a film original on which a pattern to be printed onto a wafer is printed and a reference beam that has passed through a deflection prism. On the other hand, in the computer generated holography used in this example, the shape of the interference fringes is calculated by a computer, the shape of the interference fringes is drawn by the computer, and the interference fringes are transferred to a film to create a hologram. be.

Note that the hologram 3 was manufactured to be five times the actual size of the pattern in order to be more precisely transferred (printed) onto the wafer in a later step.

FIG. 1 is a sectional view showing a part of a wafer processing step using a hologram 3 produced by the computer generated hologram. A part of the wafer processing process will be explained below based on the drawings.

In the step shown in FIG. 1(1), a photoresist 7 is applied over the entire surface of the wafer 5 with an insulating film 6 interposed therebetween.

Next, in the step of FIG. 1(2), the hologram 3 is used as a reticle, and the photoresist 7 obtained in the step of FIG. 1(1) is exposed to UV light as a laser beam. At this time, the light diffracted on the hologram 3 passes through the reduction lens 8, and the patterns reduced to 115 (restored to actual size) are superimposed and printed on the wafer 5.

Next, in the step of FIG. 1(3), the wafer 5 patterned in the step of FIG. 1(2) is immersed in a developer to be developed, and the area exposed to light is washed away.

Next, in the step shown in FIG. 1(4), unnecessary insulating film 6 is etched away by anisotropic etching using 0□.

Next, in the step shown in FIG. 1(5), the photoresist 7 is removed with a solvent, and a wafer with a reticle (hologram 3) pattern formed on the insulating film 6 is produced. A wafer with a pattern formed in this way will not have a pattern different from the actual pattern even if the reticle has minute scratches, pinholes, etc. As a result, highly reliable semiconductor devices can be efficiently manufactured.

In this embodiment, a part of the wafer processing process has been explained as an example, but a desired pattern can be formed on the wafer by arbitrarily selecting a hologram pattern such as a wiring pattern. In addition to patterning photoresist on a wafer, the present invention is also effective in all fields as a method for transferring particularly dense patterns, such as pattern transfer to photographic film.

Further, in this embodiment, the hologram was produced by computer holography, but the invention is not limited to this, and a Fresnel hologram, a Fourier transform hologram, etc. may be used depending on the type of diffracted wave of the original. Further, by selecting a photosensitive agent for recording, it is possible to use a planar hologram, a volume hologram (a hologram recorded on a photosensitive agent that is sufficiently thick compared to the interference fringe spacing), etc. depending on the purpose.

In this example, in order to more accurately transfer the pattern onto the wafer, a hologram was made five times its actual size, and later reduced to 115 mm and printed on the wafer, but the magnification can be adjusted arbitrarily depending on the type of pattern. You can choose.

Although UV light is used as the laser light in the step of FIG. 1(2), any light having a wavelength that satisfies the sensitive wavelength range of the photoresist coated on the wafer may be used.

Furthermore, the continuous wave output, pulse output, and irradiation time of the laser beam may be arbitrarily selected depending on the sensitivity of the photosensitizer.

In the process shown in FIG. 1 (4), the unnecessary insulating film 6 was removed by anisotropic etching using O2.
Other reactive gases may also be used. Further, in addition to the etching method using a chemical reaction using a reactive gas, etching may be performed using a liquid chemical or the like.

〔Effect of the invention〕

As explained above, according to the reticle and the exposure method using the same according to the present invention, a hologram is used as the reticle, exposure is performed through the hologram, and the pattern formed on the reticle is patterned on the target object (photosensitive agent). Therefore, even if minute scratches, pinholes, etc. that cannot be visually determined occur on the reticle (hologram), they will not affect the pattern transferred onto the photosensitive material. Therefore, there is no need to take great care to create scratches, pinholes, etc. on the reticle, unlike in the past, and a pattern different from the actual pattern is not transferred to the photosensitive material. As a result, even dense patterns can be transferred with high precision.

[Brief explanation of drawings]

FIG. 1 shows a sectional view of a wafer processing process according to this embodiment. In the figure, 3 is a hologram, 5 is a wafer, 6 is an insulating film, 7 is a photoresist, and 8 is a reduction lens. Part 5-'ta- ■ Sense

Claims (2)

[Claims] (1) A reticle in which a desired pattern is transferred by exposure to a photosensitive agent coated on a support, characterized in that the pattern is formed by holography. (2) An exposure method characterized by patterning a photosensitive agent using a reticle made of a hologram on which a desired pattern is formed.