JPH0445447A - Exposing mask - Google Patents

Abstract

PURPOSE:To execute exposing of fine patterns with high accuracy by providing a conductive thin film having light transmission in at least the region of a mask where light shielding films exist, thereby obviating the sticking of particles to the mask or drastically decreasing the sticking. CONSTITUTION:The exposing mask 15 is provided with mask patterns 2 consisting of an opaque metallic layer and the metallic thin film 20 having transmission to exposing light 3 and having an electric conductivity so as to cover the entire surface of the regions 4 where the mask patterns do not exist. The thin film 20 is formed by depositing Ti, W, etc., of 300Angstrom thickness on a substrate 1 and is grounded by a grounding terminal 20a. The static electricity tending to be accumulated on the substrate 1 is effectively released by the presence of such metallic thin film 20 and even if particles have the static electricity, such electricity is sufficiently released. Consequently, the fine particles do not adhere any more to the light transmission regions 4 of the mask 15 or the sticking thereof drastically decreases and, therefore, the sticking of the particles further finer (particularly 0.2 to 0.5mum) than ordinary particle sizes is prevented. The important exposing process is thus attained with the fine patterns and the high accuracy.

Description

[Detailed description of the invention] B. Industrial application field The present invention relates to an exposure mask.

BACKGROUND OF THE INVENTION Conventionally, as an exposure mask used in a photoetching process in the manufacture of semiconductor devices, for example, one shown in FIG. 6 is known.

That is, an opaque mask pattern 2 made of Cr or the like is provided on a glass substrate 1 that is transparent to exposure light, and when the exposure light 3 is irradiated, the light transmitted through the transparent area 4 without the mask pattern 2 is used for exposure processing. will be held.

FIG. 7 schematically shows the entire exposure apparatus, in which the exposure mask 5 is arranged between the illumination system 7 with a masking mechanism 6 and the reduction projection lens 8, and
is arranged directly below the projection lens 8, and predetermined exposure processing is performed. Note that 10.11 in the figure is a positioning optical system, which is used to set the exposure position with respect to the wafer 9 on the stage 12.

In the above, a so-called reticle or a photomask is used as the exposure mask 5, and various types of exposure devices other than those mentioned above are also used as the exposure device. However, if small particles such as dirt or dust adhere to the surface of the mask 5 during exposure, especially the area 4 where there is no light shielding film, the particles may not allow the exposure light to pass through or reflect diffusely, making it difficult to expose according to the mask pattern. Therefore, fine pattern exposure of integrated circuits and subsequent etching may not be realized faithfully. In conventional masks, in order to prevent the adhesion of small particles as described above, for example, HEPA (highhef
particulate air)
A filter called a filter is installed in the mask management device to remove small particles. With these measures,
There are restrictions on how to handle the masks, and it is not suitable for mass production. Moreover, if small particles adhere to the mask due to charging, the conventional dust removal mechanism is not sufficient to remove dust. This makes it difficult to cope with the exposure of ultra-fine patterns in which adhesion of particularly small particles is a problem.

OBJECTS OF THE INVENTION An object of the present invention is to provide an exposure mask that can sufficiently prevent the adhesion of fine particles or particles due to charging, and is easy to handle in terms of management.

21 Structure of the Invention That is, the present invention provides a light-shielding film provided in a predetermined pattern on a substrate that is transparent to light of a predetermined wavelength. The present invention relates to an exposure mask in which a conductive thin film that is transparent to the light is provided on the base in all regions including non-existent regions.

E, Example The present invention will be explained in detail below.

FIG. 1 shows an exposure mask 15 according to a first embodiment.

This exposure mask 15 may be manufactured as a reticle, a photomask, or the like, and basically has the same structure as the mask 5 described above.

However, the notable structure is that the mask pattern 2 is made of an opaque metal layer (for example, a laminated film of a Cr0 layer with a thickness of 200A and a Cr layer with a thickness of 300A), and the entire surface of the mask pattern non-existent area 4 is covered. , a metal thin film 20 that is transparent to the exposure light 3 and is electrically conductive is provided.

The metal thin film 20 is made by depositing, for example, Ti, W, etc. to a thickness of 300 nm on the substrate 1 by sputtering technology, and when set in an exposure apparatus (or stored) as shown in FIG. It is grounded by the ground terminal 20a.

In the above, when the mask pattern 2 is non-conductive, the metal thin film 20 is provided on the entire surface of the substrate 1 including the surface (top surface and side surface) of the mask pattern 2 as described above.

In this case, even if the pattern is insulating, it can be grounded via the thin film 20.

A specific example of the mask 15 shown in FIG. 1 may be as follows, for example.

Substrate 1: Material Quartz Size Width, length and thickness Transmittance 90% or more (436na + flatness 10μm or less 126.6±0.4 mm 126.6±0.4 mm for wavelength light 2.3±0.1 mm) Light shielding Film 2: Material Cr / Cr○ Reflectance 20% or less (436 nm thickness, 500 nm) Conductive thin film 20: Transmittance 90% or more (for 436 nm wavelength light) Thickness 300 nm or more As described above, according to the exposure mask 15 of this embodiment,
Due to the presence of the metal thin film 2o, static electricity that tends to accumulate on the substrate 1 can be effectively discharged, and even if the particles mentioned above are charged with static electricity, this static electricity can also be sufficiently discharged. As a result, the adhesion of fine particles, particularly to the light transmitting region 4 of the mask 15, is eliminated or significantly reduced, so that the particle size is even finer (particularly 0.2 to 0.0 μm) than the normal particle size (for example, about 1 μm). It can prevent the adhesion of particles (5 μm in size) and can be used in the exposure process (
In turn, the photo-etching process) can be realized with fine patterns with high precision.

Moreover, the prevention of adhesion of small particles can be realized by grounding the metal thin film 20 described above, and it is an effective dust removal method even for small particles that are difficult to prevent from adhesion only by using dust removal means such as the HEPA filter described above. Therefore, the management and handling of the mask becomes easier, and mass productivity can be greatly improved.

In the above case, as the pattern becomes finer, particles adhering to the ends of the light-shielding pattern 2 become a problem, and the particles adhering to the ends protrude to the sides of the pattern 2, changing the pattern dimensions (i.e., Therefore, if the pattern 2 is non-conductive, it is desirable that the light-transmitting conductive thin film 20 is present at least on the side of the pattern. However, the configuration shown in FIG. 1 can adequately accommodate this.

In order to manufacture the mask 15 of this embodiment, for example, a light-shielding film material is deposited on the entire surface by sputtering or the like according to a conventional method, and then the light-shielding film 2 is formed by etching after exposure to a predetermined pattern using photolithography technology. After that, a conductive film 20 is deposited over the entire surface of the substrate 1 by sputtering or the like.

FIG. 2 shows a second embodiment.

In this example, the metal thin film 20 is formed over the entire surface of the substrate 1 so that the metal thin film 20 is interposed between the mask pattern 2 and the substrate 1. Therefore, it is possible to connect to the ground via this metal thin film 20 in the same manner as described above, but this is suitable when the pattern 2 is conductive.

In order to manufacture the mask 15 of this example, for example, the conductive film 20 is deposited on the substrate 1 by sputtering or the like according to a conventional method, and then a Cr-Cr0 laminated film is deposited on the entire surface by sputtering or the like. Furthermore, the laminated film is formed into the light-shielding film 2 by exposing and etching it into a predetermined pattern using photolithography technology. At this time, the underlying metal thin film 20
will not be etched.

FIG. 3 shows a third embodiment.

The exposure mask 15 in this example is used as a so-called face-down structure, and the light shielding film (opaque metal layer) 2 is on the lower side opposite to the light incident side, and the lower side is coated with an inert material such as N2. Exposure processing is performed in a state in which a gas curtain for preventing oxidation is formed by spraying the gas 21.

In addition to its anti-oxidation function, this gas curtain 21 also has the effect of scattering or blocking fine particles adhering to or attempting to adhere to the lower surface of the mask. can be effectively prevented.

FIG. 4 shows an example in which a transparent conductive thin film 22 is also provided on the other surface of the substrate 1 in FIG. 2.

This conductive thin film 22 may be formed of the same material and by the same method as the thin film 20 described above.This conductive thin film 22 can also prevent small particles from adhering to the lower surface of the substrate 1. Exposure accuracy can be improved.

In the example shown in FIG. 5, the conductive thin film 20 in FIG. 2 is provided only in the region 4 where no light shielding film exists.

In this case as well, the conductive thin films 20 can be commonly grounded (especially when the conductive thin films are connected), and when the conductive thin films are separated, they can be grounded individually.
In any case, since there are no small particles attached to the light-shielding film-free region 4, there is no problem with exposure.

Although the present invention has been described in detail above, the embodiments described above can be further modified based on the technical idea of the present invention.

For example, the material, shape, etc. of each part of the mask may be changed in various ways. In particular, the above-mentioned transparent conductive film can be formed of metals other than Ti and W, and its film thickness may vary as long as it is optically transparent to the exposure light, and its formation method can also be electroless. It can also be formed using a metal plate or the like. The light shielding film may also be made of a material other than Cr, and its formation method may also depend on plating.

Effects of the Invention As described above, the present invention allows light to pass through at least the light-shielding film-free area of the mask (particularly all areas including the light-shielding film area, the side surfaces and edges, and the light-shielding film-free area). Because it has a conductive thin film that reduces the chance of small particles adhering to the substrate, it effectively releases static electricity that would otherwise accumulate on the substrate, and also prevents particles from being charged with static electricity. This static electricity can also be sufficiently discharged. As a result, particles are not attached to the mask or are significantly reduced, so that fine pattern exposure can be performed with high precision.

In addition, prevention of particle adhesion can be achieved by grounding the conductive thin film described above, and it becomes possible to remove small particles, which is difficult to do only by using dust removal means such as HEPA filters, making it easier to manage and handle the mask. As a result, mass productivity can be greatly improved.

[Brief explanation of drawings]

1, 2, 3, 4, and 5 are cross-sectional views of exposure masks according to each side of the present invention. FIG. 6 is a sectional view of a conventional exposure mask, and FIG. 7 is a schematic diagram of an exposure apparatus. In addition, in the symbols shown in the drawings, 1...... Substrate 2... Light shielding film 3... Exposure light 4-... ... area where no light shielding film exists (transparent area) 5.
15...Exposure mask 7...
・Illumination system 8...Projection lens 9...Semiconductor wafer 20.22...Transparent conductive thin film 21...
・・・・・・It is an inert gas.

Claims (1)

[Claims] 1. A light-shielding portion and a light-transmitting portion are provided on a substrate that is transparent to light, and the light-shielding portion has a laminated layer of a light-shielding film pattern and a transparent conductive thin film. . The exposure mask, wherein the light-transmitting part has a thin film in which the light-transmitting conductive thin film extends, and an end side of the light-shielding film is made conductive. 2. An exposure mask, in which a light-shielding film is patterned on a light-transparent substrate, and a light-transmissive conductive thin film is formed to cover at least the side surfaces of the light-shielding film and areas where the light-shielding film is not present. 3. An exposure mask in which a light-transmitting conductive thin film is formed on a light-transparent substrate, and a conductive light-shielding film is patterned on the light-transmitting conductive thin film. 4. An exposure mask, wherein a conductive thin film that is transparent to light of a predetermined wavelength is provided on a substrate that is transparent to light of a predetermined wavelength in a region where no light film exists.