JPH08227142A - Method for working optical mask - Google Patents

Abstract

PURPOSE: To enable the transfer of the intricate and fine patterns formed on a mask with high accuracy by forming recessed parts having flat bases on the main surface of a mask substrate by using an ion beam easily controllable in working sizes. CONSTITUTION: A metallic layer 3 is formed on the main surface of a substrate 2 and is patterned by etching. The substrate 2 exposed by patterning and forming of the metallic layer 3 is irradiated with the ion beam along the detailed parts of the metallic layer 3 in accordance with the pattern data of phase shift grooves 7a, by which the phase shift grooves 7a are formed. At this time, the depth, width, etc., of the phase shift grooves 7a are easily controlled if the convergent ion beam is used. The pattern data of the phase shift grooves 7a are automatically formed by ANDing the pattern data of the transparent regions B obtd. by reversing the pattern data of, for example, integrated circuit patterns from positive to negative and the pattern data obtd. by increasing the pattern width of the light shielding regions A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical mask processing technique, and more particularly to a technique effectively applied to a processing technique of an optical mask having a phase shift pattern (hereinafter, also simply referred to as a mask).

[0002]

2. Description of the Related Art In recent years, in semiconductor integrated circuits, miniaturization of elements and wirings forming the circuits, and narrowing of element spacing and wiring spacing have been advanced.

However, miniaturization of such elements and wiring,
As the element spacing and wiring spacing become narrower, the pattern transfer accuracy of a mask for transferring an integrated circuit pattern onto a semiconductor wafer (hereinafter referred to as a wafer) due to at least partially coherent light irradiation is becoming a problem. .

This will be described below with reference to FIGS. 18 (a) to 18 (d).

That is, the mask 50 shown in FIG.
When the above predetermined integrated circuit pattern is transferred onto a wafer (not shown) by a projection exposure method or the like, the phase of light transmitted through each of the pair of transmissive regions P1 and P2 sandwiching the light shielding region N is:
Since they are in phase as shown in FIG. 18B, these interference lights are mutually strengthened in the light-shielding region N sandwiched between the pair of transmissive regions P1 and P2 as shown in FIG. 18C. .

Therefore, as shown in FIG. 18D, the modulation of the light intensity distribution on the wafer is performed.
and the pattern transfer accuracy of the mask is significantly reduced.

As a means for improving such a problem, for example, a phase shift mask for producing a phase difference between the light transmitted through each of the pair of transmission regions has been proposed.

A phase shift mask is described in, for example, Japanese Patent Publication No. 62-59296, and in the above-mentioned publication, in a mask having a light shielding region and a light transmitting region, at least a pair of light transmitting regions sandwiching the light shielding region is provided. A transparent material is provided on one side to cause a phase difference between the light transmitted through each of the transmissive areas during exposure, so that these light do not interfere with each other in the area that is originally the light-shielded area and do not strengthen each other. The described mask structure is described.

The action of transmitted light in such a mask will be described below with reference to FIGS.

That is, the mask 51 shown in FIG.
When the above predetermined integrated circuit pattern is transferred onto a wafer (not shown) by a projection exposure method or the like, of the pair of transmissive regions P1 and P2 that sandwich the light shielding region N, the transmissive region P2 provided with the transparent material 52 is provided. 19 (b), between the phase of the light transmitted through the normal transmission region P1 and the phase of the light transmitted through the normal transmission region P1.
As shown in (c), there is a phase difference of 180 degrees.

Therefore, the light transmitted through the pair of transmissive regions P1 and P2 interferes with each other in the light-shielding region N sandwiched between these transmissive regions P1 and P2 to cancel each other.
As shown in (d), the modulation of the light intensity distribution on the wafer is improved, and the pattern transfer accuracy of the mask 51 is improved.

[0012]

By the way, the conventional technique for producing a phase difference between light transmitted through a pair of transmission regions is transparent when a pattern is simply and repeatedly arranged one-dimensionally. The present inventors have found that there is no problem in the material arrangement, but when the pattern is two-dimensionally arranged like an actual integrated circuit pattern, there are the following problems.

That is, in the conventional technique, the transparent material is arranged so that a phase difference is generated between the light transmitted through each of the pair of transmissive regions. In other words, the transparent material is disposed in one of the pair of transmissive regions. When they are arranged, the transparent material cannot be arranged on the other side. Therefore, when the pattern shape is complicated like an actual integrated circuit pattern, a pattern in which sufficient resolution cannot be obtained partially occurs. For example, when there is an integrated circuit pattern 53 as shown in FIG.
If a transparent material is provided in 2, the resolution of the light-shielded areas N1 and N2 will certainly improve, but the transparent area P1 or the transparent area P3
In this case, since a transparent material cannot be provided, the resolution of the light shielding area N3 cannot be improved.

It is an object of the present invention to provide a technique capable of manufacturing an optical mask capable of transferring a complicated and fine pattern formed on the mask with high accuracy.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0016]

Of the inventions disclosed in the present application, a representative one will be briefly described below.
It is as follows.

That is, in the optical mask processing method of the present invention, a mask substrate having a main surface, a light-shielding region formed of a metal layer provided on the main surface of the mask substrate, a first light transmitting region, and the first A circuit including a second light transmitting region, which is placed in contact with or close to the light transmitting region, and in which the phase of the transmitted light is inverted as compared with the phase of the transmitted light transmitted through the first light transmitting region. Pattern and the circuit pattern is exposed to exposure light having a predetermined wavelength by a reduction projection exposure apparatus to form the first and second light transmitting regions on a photoresist film on a semiconductor wafer on which an integrated circuit is to be formed. The circuit pattern on the mask substrate is formed on the semiconductor wafer as the pattern of the photoresist film by forming a clear real image of the circuit pattern by the mutual interference between the respective transmitted lights. A method for processing an optical mask for phase shift reduction projection exposure, in which a concave portion having a flat bottom surface is formed on the main surface by applying an ion beam to a predetermined place from the main surface of the mask substrate. It comprises a step of forming.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings (note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiments. , The repeated explanation is omitted).

(Embodiment 1) FIG. 1 is a sectional view of an essential part of a mask according to an embodiment of the present invention, and FIGS. 2A to 2C are sectional views of an essential part of the mask showing a manufacturing process of this mask. Figure, Figure 3
FIG. 3A is a cross-sectional view showing the exposure state of the mask shown in FIG. 1, and FIGS. 3B to 3D are explanatory views showing the amplitude and intensity of light transmitted through the transmission region of this mask.

The mask 1a of the first embodiment shown in FIG.
Is, for example, a reticle (hereinafter, referred to as 5) in which an original image of an integrated circuit pattern, which is five times as large as an actual size integrated circuit pattern, is formed by transferring a predetermined integrated circuit pattern onto a wafer (not shown) in a predetermined manufacturing process of a semiconductor device. Double reticle).

A transparent mask substrate (hereinafter, simply referred to as a substrate) 2 constituting the mask 1a has, for example, a refractive index of 1.47.
Made of synthetic quartz glass on the main surface, for example,
A metal layer 3 having a thickness of 500 to 3000 Å is patterned in a predetermined shape.

The metal layer 3 is composed of, for example, a Cr layer or a Cr oxide layer laminated on the Cr layer.
At the time of exposure, it becomes the light shielding area A. The portion where the metal layer 3 is removed becomes the transmissive region B during exposure. The light shielding area A and the light transmitting area B form an original image of the integrated circuit pattern.

In the first embodiment, the transparent film 4a having the pattern formed so as to be slightly wider than the pattern width of the metal layer 3 is arranged. That is,
On the mask 1a, a transparent film 4a, which partially protrudes from the contour of each metal layer 3 in the transmissive region B, is patterned. In other words, one transmission region B is composed of a portion covered with the transparent film 4a and a portion where the transparent film 4a is not formed.

The transparent film 4a is made of indium oxide (In
O _x ), for example, and assuming that the pattern width of the transmissive region B is 2 μm, the width of the protruding transparent film 4a is 0.5.
It is about μm.

Now, suppose that the thickness of the protruding transparent film 4a from the main surface of the substrate 2 is X1, the refractive index of the substrate 2 is n,
When the wavelength of the light emitted during exposure is λ, the transparent film 4
The a is formed so that its thickness X1 satisfies the relationship of X1 = .lambda ./ [2 (n-1)]. This is during exposure
A phase difference of 180 degrees between the phase of the light transmitted through the transparent film 4a and the phase of the light transmitted through the normal transmission area B among the light radiated to the mask 1a and transmitted through one transmission area B is provided. This is to cause it. For example, if the wavelength λ of the light irradiated during exposure is 0.365 μm (i-line) and the refractive index of the transparent film 4a is 1.5, the thickness X1 of the transparent film 4a from the main surface of the substrate 2 is X1. Is about 0.37 μm.

Although not shown, the mask 1a includes
For example, when forming the transparent film 4a, alignment marks for aligning with the metal layer 3 are formed.

Next, a method of manufacturing the mask 1a according to the first embodiment will be described with reference to FIGS.

First, as shown in FIG. 2A, a thickness of, for example, 500 to 500 is formed on the main surface of the transparent substrate 2 which has been polished and washed.
A metal layer 3 of 3000Å Cr or the like is formed by a sputtering method or the like, and then a photoresist 5a having a thickness of 0.4 to 0.8 μm is applied to the upper surface of the metal layer 3.

After pre-baking the photoresist 5a, based on the pattern data in which the position coordinates, the shape, etc. of the integrated circuit pattern of the semiconductor device, which is coded and recorded on a magnetic tape (not shown), is stored in advance,
A predetermined portion of the photoresist 5a is irradiated with the electron beam E by an electron beam exposure method or the like.

After that, as shown in FIG. 2B, the exposed portion of the photoresist 5a is removed by a predetermined developing solution,
The exposed metal layer 3 is etched by a dry etching method or the like to form a pattern in a predetermined shape.

Then, the photoresist 5a is removed by a resist stripping solution, and the substrate 2 is washed and inspected.
As shown in (c), a transparent film 4a made of indium oxide (InOx) having a thickness of about 0.37 μm from the main surface of the substrate 2 is sputtered on the main surface of the substrate 2 so as to cover the metal layer 3. It is formed by the method.

Then, on the upper surface of the transparent film 4a, for example,
A photoresist 5b having a thickness of 4 to 0.8 μm is applied, and an aluminum (A
The antistatic layer 6 of 1) is formed by a sputtering method or the like.

Then, in the pattern data of the above-mentioned integrated circuit pattern, the transparent film 4a obtained by enlarging or reducing the width of the pattern of the light shielding area A or the light transmitting area B is obtained.
On the basis of the pattern data of FIG.
The electron beam E is irradiated to b and exposed.

In the first embodiment, the pattern data of the transparent film 4a described above is automatically created by, for example, increasing the pattern width of the light shielding area A. That is, the pattern data of the transparent film 4a is not created specially like the case of creating the pattern data of the integrated circuit pattern, but is created based on the pattern data of the integrated circuit pattern.

After exposing the photoresist 5b, the mask 1a shown in FIG. 1 is manufactured through steps such as development, etching of a predetermined portion of the transparent film 4a, removal of the photoresist 5b, cleaning, and inspection. .

Using the mask 1a manufactured in this manner, the mask 1 is formed on the wafer coated with the photoresist.
To transfer the integrated circuit pattern on a, for example, the following is performed.

That is, the mask 1a and the wafer are arranged in a reduction projection exposure apparatus (not shown), and the original image of the integrated circuit pattern on the mask 1a is optically reduced to 1/5 and projected onto the wafer. Is repeatedly projected and exposed each time it is moved stepwise to transfer the integrated circuit pattern onto the entire surface of the wafer.

Next, the operation of the first embodiment will be described with reference to FIG.
This will be described with reference to (d).

In the mask 1a of the first embodiment shown in FIG. 3A, when the original image of a predetermined integrated circuit pattern on the mask 1a is transferred onto the wafer by a reduction exposure method or the like, each of the masks 1a is transferred. In the transparent region B, the transparent film 4
A phase difference of 180 degrees occurs between the light transmitted through a and the light transmitted through the normal transmission region B (FIG. 3B,
(C)).

Since the transparent film 4a is arranged at the end of each metal layer 3, the light transmitted through one transparent region B is divided into the light transmitted through the transparent film 4a and the normal transparent region B. The transmitted light has the light-shielding areas A and A adjacent to the transmission area B.
Weaken each other at the boundary with.

Therefore, the modulation of the light intensity distribution on the wafer is greatly improved (FIG. 3).
(D)). In particular, the blur at the end of each light-shielding area A projected on the wafer is significantly reduced, and the pattern transfer accuracy can be greatly improved. Since the light intensity is the square of the light amplitude, the waveform on the negative side of the light amplitude on the wafer is inverted to the positive side as shown in FIG.

By the way, the conventional technique is a technique for producing a phase difference between the light transmitted through a pair of transmission regions, in other words, a technique for producing one action in two transmission regions.

As described in the problem to be solved by the invention, when the pattern is complicated and is arranged two-dimensionally like an actual integrated circuit pattern, the pattern transfer accuracy is partially achieved. Occurs, and there is a restriction on the arrangement of the transparent material.

That is, it is very difficult to arrange the transparent material so as to improve the accuracy of transferring all the patterns on the mask.

Therefore, it is not possible to automatically create the pattern data of the transparent material. When creating the pattern data, the transparent material pattern data is taken into consideration while considering the arrangement so that the pattern transfer accuracy is not partially deteriorated. It must be created by designing a special pattern for, drawing it, and processing this pattern by computer processing.

On the other hand, the mask 1 of the first embodiment
In the case of a, since it is a technique for improving the pattern transfer accuracy by producing a phase difference in the light transmitted through one transmission region, even if the pattern formed on the mask 1a is complicated, The transparent film 4a can be arranged.

For this reason, the transparent film 4a can be easily arranged, and the pattern data of the transparent film 4a is automatically created based on the pattern data of the light-shielding area A or the transmissive area B constituting the integrated circuit pattern. It becomes possible.

As described above, according to this embodiment, the following effects can be obtained.

(1). In each transmission area B of the mask 1a, a phase difference of 180 degrees occurs between the light transmitted through the transparent film 4a and the light transmitted through the normal transmission area B, and these light rays are transmitted. Are weakened at the boundary between the light-shielding region A and the light-transmitting region B, so that the modulation of the light intensity distribution on the wafer is significantly improved. In particular, the blur at the end of the pattern image of the light-shielded area A projected on the wafer is significantly reduced, and the pattern transfer accuracy can be significantly improved.

(2) According to the above (1), even if the pattern formed on the mask is a fine and complicated integrated circuit pattern, the pattern transfer accuracy is not partially deteriorated, and the entire pattern is The transfer accuracy of can be improved.

(3). Since the transparent film 4a for shifting the phase is a technique that considers only the phase difference of the light transmitted through one transmission region B, its arrangement is complicated It will be easy.

(4) According to the above (3), the pattern data of the transparent film 4a is converted into the light-shielding area A constituting the integrated circuit pattern,
Alternatively, it can be automatically created based on the pattern data of the transparent area B.

(5). Since the pattern data of the transparent film 4a can be created in a short time by the above (3) and (4),
Mask 1a having a transparent film 4a for shifting the phase
The manufacturing time of can be greatly reduced.

(Embodiment 2) FIG. 4 is a sectional view of a main part of a mask according to another embodiment of the present invention, and FIGS. 5 (a) and 5 (b).
Is a cross-sectional view of the main part of the mask showing the manufacturing process of this mask, FIG. 6 is a block diagram of a focused ion beam apparatus used in manufacturing this mask, and FIG. 7A shows the exposure state of the mask shown in FIG. The cross-sectional views shown in FIGS. 7B to 7D are explanatory diagrams showing the amplitude and intensity of light transmitted through the transmission region of this mask.

In the mask 1b according to the second embodiment shown in FIG. 4, the transparent film 4a of the first embodiment is replaced by a means for producing a phase difference in the light transmitted through the transmissive region B during exposure. At the time of exposure, the phase shift groove 7a is formed in the substrate 2 which becomes the transmission region B.

The phase shift groove 7a is formed along the edge of the metal layer 3 which becomes the light shielding region A during exposure, that is, the metal layer 3
Is formed along the contour portion of. The width of the phase shift groove 7a is, for example, about 0.5 μm when the pattern width of the transmission region B is 2 μm.

Assuming that the depth of the phase shift groove 7a is d, the refractive index of the substrate 2 is n, and the wavelength of light irradiated during exposure is λ, the depth of the phase shift groove 7a is d. But,
It is formed so as to satisfy the relationship of d = λ / [2 (n-1)]. This is because, in the exposure, between the phase of the light transmitted through the phase shift groove 7a and the phase of the light transmitted through the normal transmission region B in each transmission region B of the light irradiated on the mask 1b. This is because a phase difference of 180 degrees is generated. For example, if the wavelength λ of the light emitted during exposure is 0.3
If the depth is 65 μm (i line), the depth d of the phase shift groove 7a is
Is about 0.39 μm.

Although not shown, the mask 1b includes
When forming the phase shift groove 7a, an alignment mark for aligning with the metal layer 3 is formed.

Next, the focused ion beam device 8 used for manufacturing the mask 1b will be described with reference to FIG.

Although not shown, the inside of the ion source 9 provided on the upper part of the apparatus main body is, for example, gallium (Ga).
Molten liquid metal, etc. are contained. An extraction electrode 10 is installed below the ion source 9, and a first lens electrode 1 formed of an electrostatic lens is provided below the extraction electrode 10.
1a and the 1st aperture electrode 12a are installed. Below the aperture electrode 12a, the second lens electrode 11b, the second aperture electrode 12b, and the beam irradiation O
A blanking electrode 13 for controlling N and OFF, a third aperture electrode 12c, and a deflection electrode 14 are provided.

With such a configuration of each electrode, the ion beam emitted from the ion source 9 is controlled by the blanking electrode 13 and the deflection electrode 14 and is held by the holder 15 before the mask 1b before pattern formation. It is designed to be illuminated.

The ion beam is used during the scanning.
For example, by setting the beam irradiation time for each pixel unit of 0.02 × 0.02 μm and setting the number of scans in advance,
The metal layer 3 or the substrate 2 can be etched.

The holder 15 is installed on a sample table 16 which is movable in the X and Y directions. The sample table 16 is moved by a laser interferometer 18 via a laser mirror 17 provided at the side. The position is recognized, and the position is adjusted by the sample table drive motor 19.

A secondary ion / secondary electron detector 20 is installed above the holder 15 so that the generation of secondary ions and secondary electrons from the workpiece can be detected. ing. Further, an electron shower radiating section 21 is installed above the secondary ion / secondary electron detector 20 described above so that the workpiece can be prevented from being charged.

The inside of the processing system described above has a structure in which a vacuum state is maintained by the vacuum pump 22 shown below the sample stage 16 in the drawing.

The operation of each processing system described above is controlled by the control units 23 to 27 provided outside the main body of the apparatus, and the control units 23 to 27 further each interface unit 28 to 32. Control computer 3 via
The structure is controlled by 3. The control computer 33 includes a terminal 34, a magnetic disk device 35 for recording data, and an MT deck 36.

Next, a method of manufacturing the mask 1b will be described with reference to FIG.
This will be described with reference to (a), (b) and FIG.

First, as shown in FIG. 5A, a metal layer 3 of, for example, 500 to 3000 Å is formed on the main surface of the polished and washed substrate 2 by a sputtering method or the like, and then the mask 1b is focused on the focused ion beam. It is held by the holder 15 of the device 8.

Then, an ion beam is emitted from the ion source 9, and the ion beam is emitted by the electrodes, for example,
If the beam diameter is focused to 0.5 μm, an ion beam current of about 1.5 μA can be obtained, and a predetermined portion of the metal layer 3 can be formed based on the pattern data of the integrated circuit pattern previously recorded on the magnetic tape of the MT deck 36. The focused ion beam is irradiated to etch the metal layer 3. At this time, the irradiation time per pixel is, for example, 3 × 10 ⁻⁶ seconds, and the number of beam scans is about 30 times. In this way, FIG.
As shown in (b), the metal layer 3 is patterned.
The pattern formation of the metal layer 3 may be performed by the electron beam exposure method or the like as in the first embodiment.

Then, a not-shown alignment mark formed on the mask 1b is irradiated with a predetermined amount of ion beam,
The generated secondary electrons are detected by the secondary ion / secondary electron detector 20, and the position coordinates of the alignment mark are calculated from the detection data.

Then, based on the calculated position coordinates of the alignment mark, the sample stage 16 is moved so that the ion beam is irradiated to the position where the phase shift groove 7a is formed during the ion beam irradiation.

Next, based on the pattern data of the phase shift groove 7a, the substrate 2 exposed by the pattern formation of the metal layer 3 is irradiated with an ion beam along the edge of the metal layer 3 to form the phase shift groove 7a (FIG. 4). ) Is formed. At this time, the focused ion beam can easily control the depth and width of the phase shift groove 7a.

In the second embodiment, the pattern data of the phase shift groove 7a is, for example, the pattern data of the transmissive area B obtained by positive / negative inversion of the pattern data of the integrated circuit pattern and the pattern of the light shielding area A. Logical product with pattern data obtained by widening the width (AN
It is automatically created by taking D).

That is, the pattern data of the phase shift groove 7a is not created specially but is automatically created based on the pattern data of the integrated circuit pattern.

Using the mask 1b manufactured as described above, the mask 1 is formed on the wafer coated with the photoresist.
To transfer the integrated circuit pattern on b, for example, the following is performed.

That is, the mask 1b and the wafer are arranged in a reduction projection exposure apparatus (not shown), the integrated circuit pattern on the mask 1b is optically reduced to 1/5 and projected onto the wafer, and the wafers are sequentially arranged. The integrated circuit pattern is transferred onto the entire surface of the wafer by repeatedly projecting and exposing each time it is moved stepwise.

Next, the operation of the mask 1b of the second embodiment will be described with reference to FIGS.

In the exposure step of transferring the original image of the predetermined integrated circuit pattern on the mask 1b shown in FIG. 7A, the light transmitted through the phase shift groove 7a and the normal light in the transmission region B of each mask 1b are The phase difference of 180 degrees is generated between the light transmitted through the transmission region B of FIG.
(C)).

The phase shift groove 7a is formed in each metal layer 3
Of the light transmitted through one transmission region B, the light transmitted through the phase shift groove 7a and the light transmitted through the normal transmission region B are light-shielded adjacent to the transmission region B. They weaken each other at the boundary between the areas A and A.

Therefore, the modulation of the light intensity distribution on the wafer is greatly improved (FIG. 7 (d)). In particular, the blurring of the edge of each light-shielded area A projected on the wafer is significantly reduced, and the transfer accuracy of the pattern projected on the wafer is significantly improved.

Since the light intensity is the square of the light amplitude, the waveform on the negative side of the light amplitude on the wafer is as shown in FIG.
As shown in (d), it is inverted to the positive side.

Also in the mask 1b of the second embodiment, as in the first embodiment, since it is a technique that considers only the phase difference in the light transmitted through one transmission region B, the mask 1b is formed on the mask 1b. Even if a complicated integrated circuit pattern is formed, the phase shift groove 7a can be easily arranged, and the pattern data of the phase shift groove 7a is based on the pattern data of the light-shielding area A or the transmissive area B that constitutes the integrated circuit pattern. Can be created automatically.

In addition, the mask 1b of the second embodiment does not include the step of forming the transparent film 4a for shifting the phase described in the first embodiment during its manufacture, and the metal layer 3 is formed by the focused ion beam. Since the phase shift groove 7a is also formed when the patterning is performed, the manufacturing time thereof can be further shortened.

As described above, according to the second embodiment, the following effects can be obtained.

(1). In each transmission region B of the mask 1b, a phase difference of 180 degrees occurs between the light transmitted through the phase shift groove 7a and the light transmitted through the normal transmission region B, and these light Are weakened at the boundary between the light-shielding region A and the light-transmitting region B, so that the modulation of the light intensity distribution on the wafer is significantly improved. In particular, the blur at the end of the pattern image of the light-shielded area A projected on the wafer is significantly reduced, and the pattern transfer accuracy can be significantly improved.

(2) According to the above (1), even if the pattern formed on the mask is a fine and complicated integrated circuit pattern, the transfer accuracy of the pattern image does not partially deteriorate, The transfer accuracy of all patterns can be improved.

(3). Since the phase shift groove 7a is a technique that considers only the phase difference of light transmitted through one transmission region B, it is easy to dispose it even in a complicated integrated circuit pattern. .

(4) Because of the above (3), the pattern data of the phase shift groove 7a can be automatically created based on the pattern data of the light-shielding area A or the light-transmitting area B forming the integrated circuit pattern. The mask 1b can be manufactured easily, and the mask 1b can be manufactured in a short time.

(5) The mask 1b does not include the step of forming the transparent film 4a for shifting the phase described in the first embodiment at the time of manufacturing the mask 1b, and the metal layer 3 is patterned by the focused ion beam. At this time, since the phase shift groove 7a is also formed, the manufacturing time thereof can be further shortened.

(6) In the mask 1b, the transparent film 4a does not deteriorate due to the cleaning process after the pattern formation.
The life can be greatly improved.

(Embodiment 3) FIG. 8 is a sectional view of an essential part of a mask according to still another embodiment of the present invention, FIG. 9 is a plan view of the essential part of this mask, and FIG. 9A and 9B are sectional views showing the exposure state of the mask of FIG. 9, and FIGS. 10B to 10D are explanatory views showing the amplitude and intensity of light transmitted through the transmission region of the mask.

First, the mask 1c of the third embodiment will be described with reference to FIGS. In the third embodiment, the transmissive region B will be described as a rectangular shape as shown in FIG.

The mask 1c of the third embodiment is, for example,
The metal layer 3 forming the light-shielding area A is a 5 × reticle that transfers a predetermined integrated circuit pattern onto a wafer (not shown) in a predetermined manufacturing process of a semiconductor device. A plurality of grooves 37 reaching the surface are provided.

Then, as shown in FIG. 9, the groove 37 is arranged in parallel along each side of the transparent region B so as to surround the rectangular transparent regions B, B. Note that, for example, the groove 37
Has a width of about 0.5 μm.

Further, a transparent film 4b made of, for example, indium oxide (InOx) having a refractive index of 1.5 is provided above the groove 37, and the transparent film 4b is formed at the time of exposure.
Also, there is a structure in which a phase difference occurs between the light transmitted through the groove 37 and the light transmitted through the transmission region B.

The thickness X2 of the transparent film 4b from the main surface of the substrate 2 is the same as that in the first embodiment. Since a phase difference of 180 degrees is generated between the phase of the transmitted light and the phase of the light transmitted through the transmission area B, X2 = λ /
It is formed so as to satisfy the relationship of [2 (n-1)]. For example, if the wavelength λ of the light emitted during exposure is 0.3
When the thickness is 65 μm (i-line), the thickness X2 of the transparent film 4b from the main surface of the substrate 2 may be about 0.37 μm.

Although not shown, the mask 1c includes
For example, when forming the groove 37 and the transparent film 4b, alignment marks for aligning them with the metal layer 3 are formed.

To manufacture such a mask 1c, for example, the following is performed.

First, a metal layer 3 having a thickness of, for example, 500 to 3000 Å is formed by a sputtering method or the like so as to cover the main surface of the substrate 2 that has been polished and washed, and then the focused ion beam device described in the second embodiment is used. The holder 15 of No. 8 holds it.

Next, based on the integrated circuit pattern data recorded in advance on the magnetic tape of the MT deck 36,
The metal layer 3 covering the main surface of the substrate 2 is patterned by an ion beam.

Thereafter, the metal layer 3 on the main surface of the substrate 2 is irradiated with an ion beam on the basis of the pattern data of the groove 37 which is previously recorded on the magnetic tape of the MT deck 36, and the groove 37 is formed on the metal layer 3. To form. The pattern data of the groove 37 is, for example, the groove 3 for the rectangular transparent region B.
By setting the arrangement rule of 7, it is automatically created.

Then, based on the pattern data of the transparent film 4b created based on the pattern data of the integrated circuit pattern and the pattern data of the groove 37, the transparent film 4b is formed similarly to the first embodiment.

Next, the operation of the third embodiment will be described with reference to FIG.
This will be described with reference to (d).

When the original image of the predetermined integrated circuit pattern on the mask 1c shown in FIG. 10A is transferred onto the wafer by the reduction exposure method or the like, the transparent film 4b and the groove are formed in each transparent region B of the mask 1c. A phase difference of 180 degrees occurs between the light transmitted through 37 and the light transmitted through the transmission region B (FIGS. 10B and 10C).

Of the light transmitted through one transmission region B, the light transmitted through the transparent film 4b and the groove 37 and the light transmitted through the transmission region B are the light-shielding regions A, which are adjacent to the transmission region B. Weak each other at the end of A.

Therefore, the modulation of the light intensity distribution on the wafer is significantly improved (FIG. 10 (d)). In particular, the blurring of the edge of each light-shielded area A projected on the wafer is significantly reduced, and the transfer accuracy of the pattern projected on the wafer is significantly improved.

Since the light intensity is the square of the light amplitude, the waveform on the negative side of the light amplitude on the wafer is shown in FIG.
As shown in (d), it is inverted to the positive side.

Also in the mask 1c of the third embodiment, since only the phase difference in the light transmitted through one transmission region B needs to be considered, the arrangement of the groove 37 and the transparent film 4b is easy, The pattern data of the groove 37 and the transparent film 4b can be automatically created based on the pattern data of the rectangular transmissive region B forming the integrated circuit pattern.

As described above, according to this embodiment, the following effects can be obtained.

(1). In each transmission area B of the mask 1c, a phase difference of 180 degrees occurs between the light transmitted through the transparent film 4b and the groove 37 and the light transmitted through the transmission area B. Since the lights are weakened at the ends of the light shielding region A, the modulation of the light intensity distribution on the wafer is significantly improved. In particular, the blur at the end of the pattern image of the light-shielded area A projected on the wafer is significantly reduced, and the pattern transfer accuracy can be significantly improved.

(2) According to the above (1), even if the pattern formed on the mask is a fine and complicated integrated circuit pattern, the pattern transfer accuracy is not partially deteriorated, and the pattern is accurately transferred. All transfer accuracy can be improved.

(3). Since the transparent film 4b for shifting the phase and the groove 37 are a technique that considers only the phase difference of the light transmitted through one transmission region B, even if the pattern is a complicated integrated circuit pattern. , Its arrangement becomes easy.

(4) By the above (3), the pattern data of the groove 37 and the transparent film 4b is automatically created on the basis of the pattern data of the light-shielding area A or the transparent area B constituting the integrated circuit pattern. be able to.

(5) Since the pattern data of the transparent film 4b can be created in a short time by the above (3) and (4),
The transparent film 4b that shifts the phase and the mask 1c in which the groove 37 is formed can be manufactured in a short time.

(Embodiment 4) FIG. 11 is a sectional view of an essential part of a mask showing still another embodiment of the present invention, FIG. 12 is a plan view of the essential part of this mask, and FIG. And a sectional view showing the exposure state of the mask of FIG. 12, FIG.
(D) is an explanatory view showing the amplitude and intensity of light transmitted through the transmissive region.

First, the mask 1d of the fourth embodiment will be described with reference to FIGS. 11 and 12.

In the mask 1d of the fourth embodiment,
As means for producing a phase difference between the light transmitted through the groove 37 and the light transmitted through the transmissive region B at the time of exposure, the substrate 2 below the groove 37 is replaced with the transparent film 4b in the third embodiment. The phase shift groove 7b is formed.

As in the second embodiment, the depth d of the phase shift groove 7b is the same as the phase of the light transmitted through the groove 37 and the phase shift groove 7b in the light irradiated on the mask 1b at the time of exposure. Since a phase difference of 180 degrees is generated with the phase of the light transmitted through the transmission region B, it is formed so as to satisfy the relationship of d = λ / [2 (n-1)]. For example, when the wavelength λ of light is 0.365 μm (i line), the phase shift groove 7
The depth d of b may be about 0.39 μm.

Furthermore, in the fourth embodiment, as shown in FIG.
As shown in FIG. 2, at the four corners of the rectangular transmission region B, for example, a rectangular minute sub-transmission region C of 0.5 × 0.5 μm is provided. This prevents the problem that the four corners of the pattern line formed on the wafer after development are not right-angled and rounded unlike the original image of the integrated circuit pattern on the mask as the integrated circuit pattern is miniaturized. This is because. That is, in the integrated circuit pattern, the sub-transmissive region C is provided at the corner where the light intensity is most likely to decrease and the distortion becomes large, and the light intensity near the corner is increased to correct the projected pattern image. There is.

Although not shown, the mask 1d includes
For example, when forming the groove 37 and the sub-transmissive area C, an alignment mark for aligning them with the metal layer 3 is formed.

To manufacture such a mask 1d, the metal layer 3 is etched by an ion beam to form the groove 3
When forming 7, the number of ion beam scans may be increased and the substrate 2 may be etched by the depth d.

Next, the operation of the fourth embodiment will be described with reference to FIG.
This will be described with reference to (a) to (d).

When a predetermined integrated circuit pattern original image on the mask 1d shown in FIG. 13A is transferred onto a wafer by a reduction exposure method or the like, the groove 37 and the phase shift groove are formed in each transmission region B of the mask 1d. A phase difference of 180 degrees occurs between the light transmitted through 7b and the light transmitted through the transmission region B (FIGS. 13B and 13C).

Of the light transmitted through one transmission region B, the light transmitted through the groove 37 and the phase shift groove 7b,
The light transmitted through the transmissive region B is weakened at the ends of the light-shielding regions A and A adjacent to the transmissive region B.

Therefore, the modulation of the light intensity distribution on the wafer is greatly improved (FIG. 13 (d)). In particular, the blur at the end of each light-shielding area A projected on the wafer is significantly reduced, and the sub-transmission area C formed at the corner of the rectangular transmission area B allows the light intensity near the corner to be reduced. Therefore, the transfer accuracy of the pattern image projected on the wafer is further improved.

Since the light intensity is the square of the light amplitude, the waveform on the negative side of the light amplitude on the wafer is as shown in FIG.
As shown in (d), it is inverted to the positive side.

Further, also in the mask 1d of the fourth embodiment, since it is only necessary to consider the phase difference in the light transmitted through one transmission region B, the groove 37 can be arranged easily.
The pattern data of the groove 37 can be automatically created by setting the arrangement rule of the groove 37 with respect to the pattern of the rectangular transparent region B forming the integrated circuit pattern.

In the fourth embodiment, the third embodiment is used.
In addition to the effects shown in (1) to (5) above, when manufacturing the mask 1d, there is no step of forming the transparent film 4b that shifts the phase described in the third embodiment, and in addition, the focused ion beam is used to remove the metal. When the layer 3 is patterned, the phase shift groove 7b can be formed at the same time, so that the manufacturing time thereof can be further shortened.

Since the mask 1d is not deteriorated by the cleaning process after forming the transparent film 4b of the mask 1c in the third embodiment, the life of the mask 1d can be greatly improved.

Although the invention made by the present inventor has been specifically described based on the embodiment, the present invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.

For example, in the mask according to the first embodiment, the case where the transparent film for shifting the phase is arranged so as to partially protrude from the contour portion of the metal layer to the transmissive region has been described, but the present invention is not limited to this. Instead, for example, like the mask 1e shown in FIG. 14, the transparent film 4c may be arranged near the center of the transmissive region B.

Also in this case, as shown in FIG.
As shown in (d), between the light transmitted through the transparent film 4c and the light transmitted through the normal transmission region B in each transmission region B of the mask 1e (FIG. 16A). A phase difference of 180 degrees occurs (FIGS. 16B and 16C), and among the light transmitted through one transmission region B, the light transmitted through the transparent film 4c and the light transmitted through the normal transmission region B are , The transparent region B and the adjacent light-shielding regions A and A are weakened at the boundary portion, the modulation (modula) of the light intensity distribution on the wafer is performed.
tion) is significantly improved (FIG. 16 (d)).

The pattern data of the transparent film 4c in this case may be created, for example, by thinning the pattern of the light-shielding area obtained by inverting the pattern data of the integrated circuit pattern in a positive / negative manner.

Further, in the mask of the second embodiment,
Although the case where the phase shift groove is arranged along the end of the metal layer has been described, the present invention is not limited to this, and the phase shift is near the center of the transmissive region B as in the mask 1f shown in FIG. The groove 7c may be formed and arranged. Also in this case, the same operation as that shown in FIGS. 16B to 16D can be obtained.

Further, for example, in a portion such as a memory cell where an integrated circuit pattern is simply arranged,
Like the mask 1g shown in FIG. 17, the phase shift groove 7d is formed in at least one of the pair of transmissive regions B and B that sandwich the light shielding region A.
May be formed.

In terms of shifting the phase of light, this is the same as the conventional technique of providing a transparent film on one of a pair of transmissive regions, but since no transparent material is provided, its manufacturing time is greatly reduced. In addition, since there is no deterioration due to cleaning after forming the transparent material, the life of the mask can be significantly improved.

Further, in the third and fourth embodiments, the case where the transmissive region has a rectangular shape has been described, but the present invention is not limited to this, and a complicated shape can be dealt with.

Further, in the first and third embodiments, the case where the transparent film is made of indium oxide has been described, but the present invention is not limited to this, and magnesium fluoride, polymethyl methacrylate or the like may be used.

In the above description, the case where the invention made by the present inventor is mainly applied to the mask used in the manufacturing process of the semiconductor device which is the background field of application has been described, but the invention is not limited to this and various applications are made. It is possible and can be applied to the technical field in which it is necessary to transfer a fine and complicated pattern onto a predetermined substrate by the photolithography technique.

[0140]

The effects obtained by the typical ones of the inventions disclosed in this application will be briefly described as follows.
It is as follows.

That is, according to the optical mask processing method of the present invention, by forming a concave portion having a flat bottom surface on the main surface of the mask substrate by using an ion beam whose processing dimensions can be easily controlled, the concave portion can be raised. It can be formed with processing accuracy. Therefore, it becomes possible to manufacture an optical mask capable of transferring a complicated and fine pattern formed on the mask with high accuracy.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of essential parts of an optical mask that is an embodiment of the present invention.

2A to 2C are cross-sectional views of a main part of an optical mask showing a manufacturing process of the optical mask.

3A is a cross-sectional view showing an exposure state of the optical mask of FIG. 1, and FIGS. 3B to 3D are explanatory views showing amplitude and intensity of light transmitted through a transmission region of the optical mask. is there.

FIG. 4 is a sectional view of an essential part of an optical mask according to another embodiment of the present invention.

5 (a) and 5 (b) are cross-sectional views of an essential part of an optical mask showing a manufacturing process of the optical mask.

FIG. 6 is a configuration diagram of a focused ion beam apparatus used when manufacturing this optical mask.

7A is a cross-sectional view showing an exposed state of the optical mask of FIG. 4, and FIGS. 7B to 7D are explanatory views showing amplitude and intensity of light transmitted through a transmission region of the optical mask. is there.

FIG. 8 is a cross-sectional view of a main part of an optical mask according to still another embodiment of the present invention.

FIG. 9 is a plan view of a main part of this optical mask.

10A is a cross-sectional view showing an exposed state of the optical masks of FIGS. 8 and 9, and FIGS. 10B to 10D show amplitudes and intensities of light transmitted through a transmission region of the optical masks. FIG.

FIG. 11 is a cross-sectional view of an essential part of an optical mask showing still another embodiment of the present invention.

FIG. 12 is a plan view of a main part of this optical mask.

13A is a cross-sectional view of the optical mask of FIGS. 11 and 12, and FIGS. 13B to 13D are explanatory diagrams showing the amplitude and intensity of light transmitted through the transmission region of the optical mask. .

FIG. 14 is a sectional view of an essential part of an optical mask according to still another embodiment of the present invention.

FIG. 15 is a sectional view of an essential part of an optical mask according to still another embodiment of the present invention.

16A is a cross-sectional view showing an exposure state of the optical mask of FIG. 14, and FIGS. 16B to 16D show the amplitude and intensity of light transmitted through a transmission region of the optical mask shown in FIG. It is an explanatory view shown.

FIG. 17 is a cross-sectional view of main parts of an optical mask according to still another embodiment of the present invention.

18A is a cross-sectional view showing an exposure state of a conventional optical mask, and FIGS. 18B to 18D are explanatory diagrams showing the amplitude and intensity of light transmitted through a transmission region of the conventional optical mask. Is.

19A is a sectional view showing an exposure state of a conventional optical mask, and FIGS. 19B to 19D are explanatory diagrams showing amplitude and intensity of light transmitted through a transmission region of the conventional optical mask. is there.

FIG. 20 is a partial plan view showing a conventional optical mask.

[Explanation of symbols]

 1a-1g Mask 2 Mask substrate 3 Metal layer 4a-4c Transparent film 5a, 5b Photoresist 6 Antistatic layer 7a-7d Phase shift groove 8 Focused ion beam device 9 Ion source 10 Extraction electrodes 11a, 11b 1st, 2nd lens Electrodes 12a to 12c First to third aperture electrodes 13 Blanking electrode 14 Deflection electrode 15 Holder 16 Sample stage 17 Laser mirror 18 Laser interference measuring instrument 19 Sample stage drive motor 20 Secondary ion / secondary electron detector 21 Electron Shower emission part 22 Vacuum pump 23-27 Control part 28-32 Interface part 33 Control computer 34 Terminal 35 Magnetic disk device 36 MT deck 37 Groove A Light-shielding area B Transmission area C Sub-transmission area E Electron beam 50,51 Conventional mask 52 Transparent material 53 Integrated circuit pattern Shielding region in the transmission region N~N3 conventional mask in emissions P1 to P3 conventional mask

Claims (1)

[Claims] 1. A mask substrate having a main surface, and a light-shielding region, a first light-transmitting region, and a first light-transmitting region made of a metal layer provided on the main surface of the mask substrate. And a circuit pattern including a second light transmission area, the phase of which is set so that the phase of the transmission light is inverted as compared with the phase of the transmission light transmitted through the first light transmission area. Is exposed by exposure light having a predetermined wavelength by a reduction projection exposure apparatus to a photoresist film on a semiconductor wafer on which an integrated circuit is to be formed. For phase shift reduction projection exposure for transferring a circuit pattern on the mask substrate onto the semiconductor wafer as a pattern of the photoresist film by forming a clear real image of the circuit pattern by interference. The optical mask processing method according to claim 1, further comprising the step of forming a concave portion having a flat bottom surface on the main surface by causing an ion beam to act on a predetermined portion from the main surface of the mask substrate. Optical mask processing method.