JPH08257780A - Mask for laser beam machining and its manufacture - Google Patents

Abstract

PURPOSE: To obtain a high quality and high laser-resistant mask by forming a first dielectric multilayer film on a translucent base plate, correcting generated flake defects with a second dielectric multilayer film and forming a mask pattern on the first film. CONSTITUTION: A first dielectric multilayer film 2 for shielding a laser beam is formed on a base plate 1 that transmits a laser beam; and also, on top of that dielectric multilayer film 2, a film is formed which is composed of a high polymer material. From the side opposite from where these films are formed, that part of the film composed of the high polymer material which is formed on the flake defects of the dielectric multilayer film 2 is exposed and removed using the film 2 as a mask. A second dielectric multilayer film 7 for shielding a laser beam is formed on the film composed of the high polymer material and on the flake defects, so that the multilayer film 7 is removed together with the film composed of the high polymer material. Then, the multilayer film 7 is left existing only on the part of the flake defects. Consequently, the laser machining mask is obtained which corrects the flake defects of the first dielectric multilayer film 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of correcting white spot defects in a multilayer film portion of a dielectric multilayer film mask for mask transfer processing by laser light.

[0002]

2. Description of the Related Art A fine circuit typified by a semiconductor is usually formed by a photolithography process using a photomask patterned with a thin film of Cr on the surface of a transparent base substrate. . At this time, if the Cr pattern on the photomask has a local excess defect or a white spot defect, it directly appears as a circuit defect. For this reason, the photomask often includes a process of correcting the defect at the manufacturing stage. For excessive defects, a common method is to directly locally remove the Cr film by a focused laser or a focused ion beam. On the other hand, as for the white spot defect, for example, “Laser Research”, Vol. 15, Vol.
Laser C as disclosed on page 21 of "Thin Film Forming Technology Utilizing Laser Light" (No. 6, February 1987).
A method has been developed in which Cr is locally deposited and corrected by the VD method.

[0003]

The above-described mask repairing method is very effective for a mask of the type in which a thin film of pure metal having a single composition such as Cr or Mo is formed on a transparent base substrate. It is a means. However, since the metal thin film generally has no laser resistance, it cannot be used for laser ablation or the like which requires a relatively high energy density. Therefore,
A dielectric multilayer film mask is used in mask transfer processing with a laser having a high energy density. Here, the dielectric multi-layer film is often used as a mirror for reflecting laser light, and it has a wavelength of the laser light used for each optical film thickness of a transparent high refractive index material and a low refractive index material. Is a so-called interference filter having a structure in which the dielectric film is formed on a translucent base substrate, and the dielectric film is formed on the transparent base substrate. The body multilayer film is locally removed to form an opening having a desired pattern. When laser light is irradiated in a state where the optical relationship is maintained such that the image of the opening is formed on the sample surface, the sample surface is processed by the laser light that has passed through the opening, following the shape of the opening.

In this dielectric multi-layered film mask, too, due to the manufacturing process, it is unavoidable that minute extra defects and white spot defects occur as in the Cr mask. On the other hand, excess defects can be locally removed by using a focused excimer laser or a focused ion beam, but for white spot defects, an optical reflection function is applied only to all large and small white spot defects. There is a serious problem that it is impossible to selectively form a multi-layered film having the above-mentioned problem by the conventional technique for correcting the white spot defect of the single-layered film.

An object of the present invention is to solve the above-mentioned problems of the prior art and provide a mask having a pattern of a defect-free dielectric multilayer film having an optical reflection function, and a method of manufacturing the same. .

[0006]

In order to achieve the above object, in the present invention, a first dielectric multilayer film for shielding the laser and a first dielectric multilayer are provided on a substrate that transmits the laser. A film made of a polymeric material is formed on the film, and the first dielectric multilayer is formed from a side of the substrate opposite to a side where the first dielectric multilayer film and the film made of the polymeric material are formed. The film made of the polymer material formed in the white spot defect portion of the first dielectric multilayer film is exposed and removed using the film as a mask, and the film made of the polymer material and the white spot defect are removed. And a second dielectric multilayer film for shielding the laser is formed on
By removing the second dielectric multilayer film together with the film made of the polymer material and leaving the second dielectric multilayer film only at the white spot defect portion, the white color of the first dielectric multilayer film is reduced. A method of manufacturing a mask for laser processing that corrects point defects was devised.

[0007]

The polymer material layer having a thickness larger than that of the dielectric multilayer film is provided on the first dielectric multilayer film formed on the surface of the transparent base substrate.

Next, when a laser beam having an energy density sufficient to remove the polymer material layer is irradiated from the surface of the transparent base substrate opposite to the surface on which the first dielectric multilayer film is formed,
Since the laser light is reflected at the part where the dielectric multilayer film exists, the polymer material layer formed on it is not processed.However, if there is a white spot defect in the dielectric multilayer film, this part is laser light. Are transmitted, a local opening having the same shape as the white spot defect is formed in the polymer material layer from the interface side with the base substrate. This opening acts as a guide for locally forming the second dielectric multilayer film described below.

Next, a second dielectric multilayer film is formed on the polymer material layer having the openings. At this time, a part of the vapor-deposited dielectric material passes through the opening of the polymer material layer and reaches the inside of the white spot defect of the first dielectric multilayer film layer, and that portion is the second dielectric material layer. It will be filled with a multilayer film. The rest is deposited on the polymeric material layer. In this state, if the polymer material layer is dissolved and removed with a solvent or the like, the portion of the second dielectric multilayer film that is attached to the surface of the polymer material layer is removed (lifted off) together with the polymer material layer, and the white spot defect portion is removed. The first dielectric multilayer film layer, which is filled with the second dielectric multilayer film, remains. In this state, the modified first dielectric multilayer film is patterned by, for example, an ion milling method, a reactive ion etching method, or an excimer laser method, so that a dielectric mask having no white spot defect can be obtained.

This patterning may be performed after forming the first dielectric multilayer film and before providing the polymer material layer.

[0011]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a diagram showing a first embodiment of the present invention, and is a diagram showing a process of correcting a white spot defect of a dielectric multilayer film mask for a KrF excimer laser having a wavelength of 248 nm. In the figure, 1 is a translucent base substrate, 2 is a first dielectric multilayer film, 3 is a white spot defect in the first dielectric multilayer film, 4
Is a polyimide film which is a polymer material layer, 5 is laser light, 6
Is an opening formed in the polymer material layer on the white spot defect, 7 is the second dielectric multilayer film layer, 8 is the dielectric composition being evaporated, 9 is the dielectric multilayer film after the white spot defect is corrected, 10 is a Cr mask, 1
Reference numeral 1 is a reactive plasma, 12 is a mask pattern formed on the dielectric multilayer film after white spot defect correction, and 13 is a completed defect-free dielectric multilayer film mask. In this embodiment, the laser light used has a wavelength of 248 nm.
Since it is an excimer laser, a synthetic quartz glass substrate is used as the base substrate 1, and hafnium oxide (HfO ₂ ) and silicon oxide (SiO ₂ ) are alternately used as electron beam evaporation (EB evaporation) as the dielectric multilayer film 2. Was used.
At this time, the thickness of the dielectric multilayer film 2 is about 0.8 μm.

Then, a thickness of 3 μm is formed on the dielectric multilayer film 2.
A polyimide layer 4 of m is formed and baked at a temperature lower than the temperature at which it completely cures to a semi-cured state (b). Here, it has been experimentally confirmed that, in addition to the advantages described below, the semi-cured state has an advantage that processing from the back surface is easier because processing can be performed with a lower laser energy than in the completely cured state. At this time, the polymer material layer 4 formed on the dielectric multilayer film 2 is irradiated with light from the back surface of the substrate 1 using the dielectric multilayer film 2 as a mask and transmitted through the white spot defect portion 3 (excimer in this embodiment). In principle, any material that absorbs, decomposes, and vaporizes (laser) may be used, but a material having heat resistance that does not deteriorate due to heat applied when the second dielectric multilayer film is formed in a later step is preferable.

Next, with respect to the dielectric multilayer film having the polyimide layer formed on the surface in this manner, it is sufficient to remove the polyimide layer 4 from the surface of the base substrate opposite to the side where the dielectric multilayer film is formed. When the entire surface is irradiated with an excimer laser having an energy density while scanning, the polyimide layer 4 is decomposed and vaporized by the excimer laser that has passed through the white spot defect 3, and the polyimide layer is passed through the dielectric multilayer film to the inside of the dielectric multilayer film. The opening 6 having the shape of the white spot defect 3 is formed (c). In this embodiment, the size is 5 mm square and 300 mJ /
A KrF excimer laser having an energy density of cm ² was used.

After cleaning the inside of the opening of the polyimide in which the opening is formed in this way, when it is completely cured in a furnace, a mortar-shaped taper is formed in the polyimide of the opening due to contraction (d). This taper makes it easier for the deposition material to enter the opening when the dielectric multilayer film is deposited next time.

Next, from the polyimide surface side again, HfO ₂
When a second dielectric multilayer film 7 made of SiO ₂ and SiO ₂ is formed with the same structure as the first dielectric multilayer film 2, it is also dielectric inside the white point defect 3 via the opening along with the polyimide surface. The body multilayer film 7 is formed (e). In this state, when the polyimide 2 is dissolved and removed by a solvent, the second dielectric multilayer film 7 on the polyimide is also lifted off and removed together with the polyimide, and later the dielectric substance in which the white spot defect is corrected by the second dielectric multilayer film. The multilayer film 9 remains (f).

After forming a defect-free Cr mask 10 in which white spot defects are corrected by an existing method used for a semiconductor photomask or the like on the dielectric multilayer film 9 (g), etching is performed by a reactive plasma 11. Thus, the opening pattern 12 is formed (h), and then the Cr film is removed by etching to obtain the defect-free dielectric mask 13 (i).

Here, in order to form an opening in the polyimide on the white spot defect, a laser focused from the polyimide layer side is irradiated to the position of the defect previously detected by using a convergent excimer laser or the like to expose only the polyimide layer. A method of locally removing the laser spot is also conceivable, but it is almost impossible to make the laser spot to have exactly the same shape and size as the white spot defect in this method. Therefore, naturally, a laser spot having a size including all the white spot defects is irradiated. It will be. Therefore, when the second dielectric multilayer film is formed to fill the white spot defect, the second dielectric multilayer film is stacked on the first dielectric multilayer film around the white spot defect. , A big step will be created. This step becomes extremely inconvenient if a mask opening accidentally interferes with this step when a mask pattern is formed on the dielectric multilayer film in a later step. Therefore, the method of locally removing only the polyimide layer by irradiating the focused laser from the side of the polyimide layer is not suitable when manufacturing a mask using the dielectric multilayer film which is the object of the present invention.

Even if the above steps (g) to (i) are performed by the same method as the lithography step for forming a wiring pattern in the conventional semiconductor manufacturing process, a similar defect-free dielectric mask 13 can be obtained. it can.

According to this embodiment, the first formed on the substrate
By irradiating a laser from the back surface side of the substrate to the entire back surface using the dielectric multilayer film 2 of the layer as a mask, the laser passing through the white spot defect portion of the dielectric multilayer film 2 causes the laser light to pass over the dielectric multilayer film 2. Since only the portion of the polyimide film formed above on the white spot defect can be selectively removed, there is an effect that the white spot defect can be corrected without detecting its position.

In the above embodiments, the step of forming an opening in a semi-cured state of polyimide and then completely curing the polyimide has been described. However, the opening may be formed by excimer laser processing after completely curing the polyimide from the beginning.

Next, a second embodiment of the present invention will be described.

FIG. 2 is a diagram showing a process for the second embodiment of the present invention. In the figure, 14 is a dielectric multilayer film in which a mask pattern is formed in advance, 15 is an opening of a mask, 16 is a metal vapor deposition mask, and 17 is a projection lens. The dielectric multilayer films 14 and 7 and the polyimide material are the same as in the first embodiment.

First, a dielectric multilayer film mask 1 having an opening pattern formed in advance by a lift-off method or a lithography method used in a conventional semiconductor manufacturing process.
4 is manufactured (j), and a semi-cured polyimide layer having a thickness of 3 μm is formed on this dielectric film surface (k).

Next, after metal is sputter-deposited on the synthetic quartz glass substrate, a pattern reverse to that of the mask 14 is formed by photolithography and etching, and the metal spot is vapor-deposited in which white spot defects are corrected by the above-mentioned conventional technique. Mask 1
Prepare 6. At this time, a portion corresponding to the opening 15 of the dielectric multilayer film mask 14 has an island-shaped pattern on the metal vapor deposition mask 16. When the island pattern is projected onto the sample surface, the size thereof is the opening. It should be slightly larger than the size of 15. Using the metal vapor deposition mask 16 formed in this manner as a mask, the dielectric multilayer film mask is formed by performing reduction or 1: 1 projection processing from the back surface of the polyimide-coated dielectric multilayer film mask 14 through the dielectric multilayer film with an excimer laser. In addition to the 14 regular openings, the openings 6 are formed only in the polyimide on the white spot defects that happened to occur, selectively and following the shape of the white spot defects (1).

In this way, the dielectric multilayer film mask 14 masked with polyimide except for the white spot defect portion is washed and then completely cured in the furnace (m). When the second dielectric multilayer film 7 is formed from the polyimide coated surface side, the surface of the glass substrate 1 inside the white spot defect 3 can be filled with the second dielectric multilayer film 7 through the opening 6 together with the polyimide surface. Yes (n). Then, when the polyimide is dissolved with a solvent or the like, the second dielectric multilayer film adhered on the polyimide is lifted off and removed, and the white spot defect portion is filled with the second dielectric multilayer film. Is obtained (o).

According to this embodiment, the white spot defect of the pattern after forming the pattern of the dielectric multilayer film can be surely removed without specifying the position of the white spot defect by using the pattern as a mask. Is obtained.

Next, another embodiment of the present invention will be described.

In the third embodiment of the present invention, instead of the polyimide 4 of FIG. 1 in the first embodiment, a so-called positive type photosensitive resist in which a portion irradiated with light is removed by development, Instead of the laser 5, an ordinary ultraviolet light source for exposure is used.

That is, a photosensitive resist is applied to the surface of the dielectric multilayer film, and ultraviolet light for exposure is applied from the back surface through the dielectric multilayer film to apply it on the white spot defect portion of the dielectric multilayer film. The exposed photosensitive resist is exposed, and then the photosensitive resist is developed to remove only the exposed portion to form an opening in the photosensitive resist layer only on the white spot defect portion. .

If the mask substrate having the photosensitive resist layer having openings on the white spot defects thus formed is subjected to the same steps as the step after (e) shown in FIG. Can be obtained.

In the same manner, the second aspect of the present invention described above.
In the embodiment, a similar dielectric multilayer mask can be obtained by using a positive type photosensitive resist instead of polyimide.

A method of processing a circuit board by using the present invention described above will be described below.

In FIG. 3, a via hole for interlayer connection is processed in a polyimide insulating layer by an excimer laser method using a defect-free dielectric multilayer film according to the present invention, and then the inside of the via hole is filled with Cu plating. It is a diagram schematically showing a cross section of a circuit board at the stage of making a multilayer circuit by repeating the process of forming a Cu wiring layer on the top.

In the figure, reference numeral 22 is a base circuit board, 23 is a conductor filled in a through hole formed in the circuit board 22, 24 is a polyimide layer for interlayer insulation,
Reference numeral 25 is a Cu pad for receiving a via hole, 26 is a Cu wiring, 27 is a Cu plating filled in the via hole, and 28 is a via hole before Cu plating.

In FIG. 3, the via hole 28 is excimer laser-processed at a predetermined position by using the dielectric multilayer film mask of the present invention, for example, by the method described later.

FIG. 4 shows one method of excimer laser processing a via hole in a polyimide insulating layer using the dielectric multilayer film mask of the present invention. In the figure,
29 is a mask stage, 30 is a 1: 1 projection lens, 31
Is a circuit board to be a processed sample, 32 is a sample stage, and 33 is an excimer laser having a wavelength of 248 nm.

Since the inverted image of the mask is formed on the sample surface by the projection lens, the sample surface is laser-scanned in the same pattern as the pattern of the mask by moving the mask stage and the sample stage relative to each other at the same speed. Can be processed.

FIG. 5 shows another method of excimer laser processing a via hole in a polyimide insulating layer using the dielectric multilayer film mask according to the present invention. In the drawing, 34 is an image erecting optical system, and 35 is a mask sample integrated holder.

Image erecting optical system 34 and 1: 1 projection lens 3
When the normal-size erect image of the mask 13 is formed on the sample surface by 0, the sample and the sample are moved together, so that the sample surface can be laser processed in the same pattern as the pattern of the mask.

In the above embodiment, the same laser as that used in the actual transfer processing was used to correct the white spot defect.
The same light source is not necessarily required to achieve the object of the present invention, and the light source used to correct the white spot defect is a polymer material layer which is reflected by the dielectric multilayer film and is formed on the dielectric multilayer film. Any substance having a function of being absorbed and decomposing and vaporizing the polymer material layer may be used.

[0042]

As described above, according to the present invention, it is possible to easily correct a white spot defect of a dielectric multi-layer film layer which could not be conventionally corrected by a very simple method. Obtainable. The laser processing was hardly applied to the processing of the large area such as a circuit board which is absolutely unacceptable due to the problems of the laser resistance of the mask and the white spot defect, but the application range of the laser processing is greatly expanded by the present invention. The effect is that you can do it.

[Brief description of drawings]

FIG. 1 is a diagram showing a process of forming a mask pattern after selectively filling only white spot defect portions of a dielectric multilayer film with a second dielectric multilayer film.

FIG. 2 is a diagram showing a process for selectively filling only white spot defect portions of a patterned dielectric multilayer film with a second dielectric multilayer film.

FIG. 3 is a diagram showing a cross section of a multilayer circuit board that has been via-hole processed using a dielectric multilayer film mask with a defect repaired according to the present invention.

FIG. 4 is a diagram showing a method for excimer laser projection processing using a dielectric multi-layered film mask in which a defect is corrected according to the present invention.

FIG. 5 is a diagram showing a method for excimer laser projection processing using a dielectric multilayer film mask with defect correction according to the present invention.

[Explanation of symbols]

1 ... Translucent base substrate, 2 ... First dielectric multilayer film, 3 ...
White spot defect, 4 ... Polyimide, 5 ... Excimer laser light, 6
... Aperture formed in polyimide, 7 ... Second dielectric multilayer film, 8 ... Evaporated dielectric composition, 9 ... Dielectric multilayer film with white spot defects corrected, 10 ... Cr mask, 11 ... Reactivity Plasma, 12 ... Pattern openings formed in the dielectric multilayer film, 13 ... Completed defect-free dielectric multilayer film mask, 14 ...
Dielectric multi-layer film mask, 15 ... Pattern openings previously formed in the dielectric multi-layer film, 16 ... Metal vapor deposition mask, 17
... Projection lens, 22 ... Base circuit board, 23 ... Conductor filled in through hole, 24 ... Inter-layer insulating polyimide layer,
25 ... Cu pad, 26 ... Cu wiring, 27 ... Via hole Cu plating, 28 ... Opening formed in polyimide, 2
9 ... Mask stage, 30 ... 1: 1 projection lens, 31 ...
Sample, 32 ... Sample stage, 33 ... Excimer laser, 3
4 ... Image erecting optical system, 35 ... Mask, sample integrated holder

Front page continued (72) Inventor Yoichi Oyuki 1 Horiyamashita, Hitachi, Ltd., Hadano, Kanagawa Pref., General Computer Division, Hitachi, Ltd. (72) Inventor, Tsutomu Imai 1 Horiyamashita, Hadano, Kanagawa Pref., General Computer Division, Hitachi, Ltd. (72) Inventor Kenkichi Suzuki 3300 Hayano, Mobara-shi, Chiba Hitachi, Ltd. Electronic Devices Division

Claims (9)

[Claims] 1. A first dielectric multilayer film that shields the laser and a film made of a polymer material are formed on the substrate that transmits the laser, and the film of the polymer material is formed on the first dielectric multilayer film. First
Is formed in the white spot defect portion of the first dielectric multilayer film from the side opposite to the side where the dielectric multilayer film and the film made of the polymer material are formed. The exposed film made of the polymer material is removed by exposure, and a second dielectric multilayer film for shielding the laser is formed on the film made of the polymer material and on the white spot defect. The second dielectric multilayer film is removed together with the film made of the polymer material, and the second dielectric multilayer film is left only at the white spot defect portion, whereby the white spot defect of the first dielectric multilayer film is removed. A method for manufacturing a mask for laser processing, comprising: 2. The laser according to claim 1, wherein after the dielectric multilayer film is pre-patterned, a film made of the polymer material is formed, and only the patterned dielectric film is exposed. Manufacturing method of processing mask. 3. The method for manufacturing a mask for laser processing according to claim 1, wherein after the white spot defect of the first dielectric multilayer film is corrected, the first dielectric multilayer film is patterned. 4. A film made of the polymer material formed on the dielectric multilayer film is exposed in the semi-cured state,
The method of manufacturing a mask for laser processing according to claim 1, wherein the mask is completely cured after the exposure. 5. The method for manufacturing a laser processing mask according to claim 1, wherein the exposure is performed by the laser. 6. The method for manufacturing a laser processing mask according to claim 5, wherein the film made of the polymer material is a polyimide film, and the removal is performed by exposing the polyimide film with the laser. . 7. The mask for laser processing according to claim 1, wherein the film made of the polymer material is a resist film, and the removal is performed by exposing the resist film with ultraviolet light. Manufacturing method. 8. A pattern formed on a substrate which transmits a laser by a first dielectric multi-layered film which shields the laser and a white spot defect portion is corrected by a second dielectric multi-layered film which shields the laser. A mask for laser processing, comprising: 9. The laser processing mask according to claim 8, wherein the second dielectric multilayer film is made of the same material as that of the first dielectric multilayer film.