JPS5836493B2 - How to use a hot mask - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for processing a medium to be processed in the manufacturing process of semiconductor integrated circuits, etc.
For example, the present invention relates to a method for manufacturing a photomask used for selectively exposing a photoresist film on a semiconductor substrate, and particularly to a method for partially adding and modifying a photomask.

In general, as photomasks for selective exposure such as photomasks for semiconductor integrated circuits, so-called metal masks that use metals such as chromium have recently replaced emulsion masks that use emulsions of silver halide compounds. Masks are often used.

This metal mask is superior to emulsion masks in terms of durability, resolution, and chemical resistance.

To manufacture this metal mask, for example, first, a metal layer such as chromium is formed on a substrate such as glass by vapor deposition or sputtering, a photoresist is applied on this metal layer, and a photoresist is applied. This is performed by selectively exposing and developing the metal layer using a photoresist as an etching mask.

In order to selectively expose the metal mask, a so-called master redicle is used to expose the metal mask.

In the case of very complex patterns such as those of recent large-scale integrated circuits, in order to manufacture metal masks using this master redicle, the circuit design process, pattern generation data, creation process, pattern generation process, etc. It takes several weeks to several months to complete the process, which is a complicated step-and-repeat process.

Conventionally, when performing selective exposure on, for example, a semiconductor wafer using the metal mask, if the pattern needs additional correction, the process returns to the pattern generation data creation process and is remanufactured. As a result, I have to waste my time again, causing inconvenience.

In view of the above-mentioned conventional inconveniences, the present invention provides a method for easily modifying the photomask by additionally modifying the required pattern when the pattern of the master reticle or metal mask needs to be additionally modified. This provides an additional modification method for metal masks that can improve the yield rate of non-defective products and save man-hours.

That is, the present invention includes a step of selectively forming an organic film on one principal plane of a transparent substrate on which a patterned layer that shields ultraviolet and visible light is formed, and a process in which the organic film blocks ultraviolet and visible light. The present invention relates to a method for manufacturing a photomask for photolithography, which comprises a step of implanting particles accelerated to high energy.

The details of the present invention will be explained below with reference to the embodiments shown in the drawings. explain.

As shown in FIG. 1, a photomask for selective exposure of a photoresist used for manufacturing integrated circuits and the like corresponds to patterns of wiring and elements on a substrate 1 made of, for example, transparent glass. For example, a thin metal layer or metal oxide film layer 2 of chromium (Or), chromium oxide (Cr203), nickel (Ni), copper (Cu), iron oxide (Fe203), etc. is formed. In this case, several types of masks with such structures are configured as one set.

Then, as shown in FIG.
If it becomes necessary to do so, first, as shown in FIG. 3a, apply a negative type film to the upper surface of the transparent glass substrate 1 so as to cover the metal layer or metal oxide film layer 2. A photoresist film 3 is formed.

The photoresist used at this time was O manufactured by Tokyo Ohka Kogyo Co., Ltd.
MR83, OSR or KPR made by Kodak in the United States
, KMER, KTF & USA PHILIPA I{UNT
Waycoat Resis manufactured by CHEMICAL
Any negative-type organic photosensitive resin such as T may be used.

Further, the thickness of the photoresist coating may range from 500 Å to several microns in order to obtain a good completed additional correction pattern.

Next, using an exposure device prepared in advance, the photoresist film in the portion of the additional correction pattern (FIG. 2, 3') is exposed (FIG. 3b).

As shown in FIG. 4, the exposure apparatus includes, for example, a light source 5 such as a mercury (Hg) lamp, a shutter 6 that blocks light from the light source 5, and a metal A slit pattern 7 that can be freely adjusted to a size corresponding to an arbitrary multiple of the size of the additional correction pattern formed on the mask 10, and a slit pattern 7 that can be freely adjusted to a size corresponding to an arbitrary multiple of the size of the additional correction pattern formed on the mask 10, and a slit pattern 7 that reduces the irradiation range defined by the slit pattern 7, and It consists of a reduction lens 8 for exposing the metal mask to light, a half-Lar 9 and a lens 11 for observing the exposed surface of the metal mask.

The metal mask 10 can be moved horizontally as appropriate.

Therefore, the irradiation position of light on this metal mask is adjusted.

The photoresist film irradiated by the exposure apparatus having such a structure is developed by a well-known method to form the image shown in FIG. 3C? As shown, only the photoresist film in the area to be additionally corrected remains.

Next, as shown in Figure 3d, ions are extracted from the plasma formed by an appropriate ion source using an appropriate method, and only the desired ions are separated by mass, and the desired dose is obtained at the desired acceleration voltage. It is implanted into the photoresist film 8 so that it becomes .

At this time, the ions to be implanted are 31 p+, 11
It may be an ion such as +20 +40 + B or Ne Ar, or it may be an ion composed of a plurality of atoms 2 such as 49+70+ or BF or B203.

Furthermore, it is not necessarily necessary to perform mass separation, and all ions generated from the ion source may be implanted.

Additionally, the larger the mass of the ion, the more desirable it is.

At this time, the chromium (C!r), chromium oxide (Cr20
3), nickel (NiL copper (Cu), iron oxide (Fe20
There is no problem even if the above-mentioned ions are implanted into the entire surface of a metal mask made of a film such as 3).

The state after ion implantation is shown in FIG. 3e, and the ion-implanted photoresist film 3' is a film having the property of shielding ultraviolet rays and an 'lx ivy (7), as shown in FIG. The additional modification of the element pattern is completed as shown in 3'.

As mentioned above, when ion implantation is performed at a certain acceleration voltage, as the amount of ions implanted into the photoresist film is increased, the photoresist film hardens and at the same time partially carbonizes, making it difficult to absorb light in the ultraviolet and visible regions. The drop-off rate decreases significantly.

This tendency also applies to other organic coatings such as polymethyl, meta,
Acrylate, rubber, novolac resin, epoxy resin,
It was found that a similar tendency was observed in the case of films made of polyethylene, polystyrene, poly-ide, etc.

For example, if an accelerating voltage of 130
When implanting 3ip+ ions with Kev, if the ion implantation amount is 1015 ions/c, the wavelength is 4.
Almost no light of 60 mμ or less passes through.

In Figure 5, the film thickness is approximately 4mm. oooA photoresist (OM
R83) Apply 3ip+ to the coating at an acceleration voltage of 130Kev.
It shows the spectral transmission characteristics before and after ion implantation when 0 zons/crrt was implanted.

In FIG. 5, 15 represents the spectral transmission characteristics before ion implantation, and 16 represents the spectral transmission characteristics after ion implantation.

As can be seen from FIG. 5, when high-concentration ions are implanted into a photoresist film, the transmittance of the photoresist film in the ultraviolet and visible regions decreases significantly depending on the amount of ion implantation.

Furthermore, if the photoresist film thickness and implantation amount are constant, this tendency becomes more pronounced as the accelerating voltage becomes higher.

On the other hand, by implanting high-concentration ions into the photoresist film, the adhesion between the photoresist and the glass substrate becomes stronger, and at the same time, the mechanical strength of the photoresist film is different from that of conventional photoresist films. It is completely different and has excellent mechanical strength comparable to metal oxides such as chromium oxide (Cr203).

Furthermore, by subjecting the photoresist to a high-concentration ion implantation process, its chemical resistance is completely different from that of conventional photoresists and has been improved. It is now resistant to chemicals such as OMR remover manufactured by Kogyo Co., Ltd., and can be cleaned in these chemicals in the same way as conventional metal masks.

Further, in this embodiment, only the case where a negative type photoresist is used has been described, but a positive type photoresist (for example, AZ-1 manufactured by Shipley Co., Ltd. in the United States) is used.
350, AZ-111, etc.), the present invention can be used to perform additional modification of the pattern as well.

In addition, if the part to be additionally corrected does not require high precision, for example, apply an organic film with a brush or brush, and then perform the ion implantation process as described above to add the part. It is also possible to make modifications.

Further, in this embodiment, an example in which positive ions are implanted has been described, but the ions may be either positive ions or negative ions.

Furthermore, similar results can be obtained by injecting particles that are in an ion state during acceleration and become neutral particles immediately before injection.

As described above, in the method for additionally modifying the element pattern of a photomask according to the present invention, particles accelerated to high energy are implanted into the photoresist film or other organic film. Conversion into a substance with completely different characteristics from the original properties of the organic film, including
This is an innovative method in that it can be used as a pattern in a photomask, and the advantage of using the present invention is that the manufacturing process can be simplified and shortened.
Enables reduction of mask unibody.

Further, other advantages obtained by adopting the present invention are as described above.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional metal mask, and FIG. 2 is a plan view of a metal mask obtained according to the present invention. FIG. 3 is a process diagram for manufacturing a metal mask according to the present invention. FIG. 4 is a schematic diagram of an exposure apparatus used in the present invention. FIG. 5 is a graph showing the spectral transmission characteristics before and after ion implantation into the photoresist film. Explanation of symbols, 1...Transparent substrate, 2...Metal 1 or,
Metal oxide film, 3... Photoresist film, 3'
...Photoresist film subjected to ion implantation treatment, 4
... Various ions, 5... Spectral transmission characteristics of the photoresist film before ion implantation, 6... Spectral transmission characteristics of the photoresist film after ion implantation.

Claims (1)

[Claims] 1 A step of selectively forming an organic film on one principal plane of a transparent substrate on which a patterned layer that shields ultraviolet and visible rays is formed, and a process of high energy in 1 in which the organic coating becomes able to shield ultraviolet and visible rays. 1. A method for producing a photomask for photolithography, the method comprising the step of: implanting particles accelerated to .