JPH0829963A - Half tone type phase shift mask and resist light exposure method - Google Patents

Abstract

PURPOSE:To provide a half-tone type phase shift mask capable of making the size of a pattern to be formed at a resist constant regardless of the position at which each light transmission area has been formed. CONSTITUTION:A half-tone type phase shift mask is made of the light transmission area group composed of a half light shield layer 14 and plural light transmission areas 12A to 12C formed on a transparent board 10, and the phase of light passing the half light shield layer 14 differs from that of light passing the light transmission area 12A to 12C. And, as the diffraction lights passing the neighboring light transmission areas interfere with each other, the light transmission areas 12A to 12C of the light transmission area group are arranged more closely, and the size of each of the light transmission areas 12B and 12C positioned on the most outer circumference of the light transmission area group differs from that of the light transmission area 12A positioned in another area of the light transmission area group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a halftone phase shift mask used for various pattern forming techniques in the manufacture of semiconductor devices, and a resist exposure method using the halftone phase shift mask.

[0002]

2. Description of the Related Art A photomask used in a pattern transfer process, that is, a so-called lithographic process in manufacturing a semiconductor device is used for transferring a pattern shape on the photomask to a resist formed on a substrate made of a wafer, for example. . Hereinafter, unless otherwise specified, a resist formed on a substrate such as a wafer will be simply referred to as a resist. The dimensions of pattern processing in semiconductor devices and the like are becoming finer year by year. A conventional photomask composed of a light-shielding region and a light-transmitting region cannot obtain a resolution of about the wavelength of the exposure light of the exposure apparatus used in the lithography process, and is required in the manufacture of semiconductor devices and the like. It is becoming difficult to obtain high resolution. Therefore, in recent years, so-called phase shift masks having a phase shift region that makes the phase of light different have been used in place of such conventional photomasks. By using a phase shift mask, it is possible to form a fine pattern that cannot be formed by a conventional photomask.

The conventional phase shift mask has a light transmitting region,
It is composed of a light-shielding region that shields light and a phase shift region made of a light-transmitting substance that transmits light having a phase different from that of light passing through the light-transmitting region. 12A, 12B, and 12C are schematic partial cutaway views of a typical conventional edge-enhanced phase shift mask. In the figure, 10 is a substrate, 112 is a light transmitting region, 116 is a light shielding region, 118
Is a phase shift region, 120 is a light transmitting material layer, and 122 is a light shielding layer. By providing the light transmitting material layer 120, the phase of light passing through the light transmitting region 112 and the phase of light passing through the phase shift region 118 can be made to differ by 180 degrees, for example.

In the conventional phase shift mask, a fine pattern cannot be formed unless the shape or position of the phase shift region is precisely controlled. In addition, depending on the pattern shape, the phase shift region may cause light interference even in other light transmitting regions that should not receive light interference. In such a case, the phase shift region cannot be formed.

As a kind of phase shift mask for solving the problems of the conventional phase shift mask, the phase and the light transmission of the light passing through the semi-shield layer are composed of a semi-shield layer and a light transmitting region. The phase of light passing through the area is, for example, 18
There are halftone phase shift masks that differ by 0 degrees. The halftone phase shift mask can solve the above-mentioned problems of the conventional phase shift mask and further improve the resolution. Further, it is necessary to form a light-transmitting material layer and a light-shielding region required in the phase shift mask.
Since a single forming step of forming the light transmitting region is required instead of the single forming step, the halftone phase shift mask is easily manufactured, and the degree of generation of defects during the mask manufacturing is low. Has the advantage.

Schematic partial cutaway views of the halftone phase shift mask are shown in FIGS. 7A and 7B. In the figure, reference numeral 10 is a substrate, 12 is a light transmitting region, and 14 is a semi-light-shielding layer. A phase shift layer 20 is formed below or above the semi-shielding layer 14. The phase shift layer 20 is
It is made of a light transmitting material for making the phase of light passing through the light transmitting region 12 and the phase of light passing through the semi-shielding layer 14 different from each other. In this case, by appropriately setting the thickness d of the phase shift layer 20, the difference between the phase of light passing through the light transmitting region 12 and the phase of light passing through the semi-shielding layer 14 is 180.
Degree. The halftone phase shift mask shown in FIG. 7C is a so-called substrate digging type. By forming the concave portion 16 in the substrate 10, the phase of light passing through the light transmitting region 12 and the phase of light passing through the semi-shielding layer 14 can be made different from each other. In this case,
By appropriately setting the depth d ′ of the concave portion 16, the phase difference between the light passing through the light transmitting region 12 and the light passing through the semi-shielding layer 14 becomes 180 degrees.

In the halftone phase shift mask, the amplitude transmittance of the semi-shielding layer 14 is larger than 0 and is such that the resist is not resolved, for example, 20 to 45%. The light intensity transmittance is about 4 to 20%. Then, by controlling the thickness of the semi-light-shielding layer 14, a desired amplitude transmittance or light intensity transmittance can be obtained. Conventionally, the light intensity transmittance of the semi-shielding layer 14 is set to a uniform value over the entire surface of the mask. Then, in order to transfer the pattern shape provided on the halftone type phase shift mask to the resist, the light that has passed through the semi-shielding layer 14 having a predetermined light intensity transmittance and a phase, and a 180 degree semi-shielding layer Uses the interference of light that has passed through different light transmission regions 12.

In the exposure method using the halftone phase shift mask, the light transmitting region 12 and the semi-shielding layer 14 are used.
Are adjacent to each other. Therefore, the light passing through the light transmitting region 12 is interfered with by the light passing through the semi-shielding layer 14, and the light passing through the light transmitting region 12 is actually formed on the resist more than the size of the pattern originally formed on the resist. The pattern size becomes smaller. Therefore, usually, a pattern of a desired size is formed on the resist,
The size of the pattern (size of the light transmission region) to be formed on the halftone phase shift mask is increased.
In addition, increasing the size of the pattern (size of the light transmission area) to be formed on the halftone phase shift mask in this way is sometimes referred to as biasing the size of the light transmission area. The difference between the size of the pattern to be formed on the tone phase shift mask (the size of the light transmission region) and the pattern of the desired size to be formed on the resist may be called the bias amount.

For example, KrF laser light (wavelength: 248 nm) is used as the exposure light, the numerical aperture (NA) of the exposure device is 0.5, the coherence degree (σ) is 0.5, and the light intensity of the semi-shielding layer 14 is set. When a halftone phase shift mask having a transmittance of 10% is used and a pattern of 0.30 μm is formed on a resist, the size of the light transmission region 12 on the halftone phase shift mask is 0. 35
μm. That is, the bias amount is 0.05 μm.

[0010]

As described above, the halftone phase shift mask is relatively easy to manufacture,
Further, the exposure method using the halftone type phase shift mask has various advantages that the resolution can be improved. However, as compared with the conventional photomask, there is a problem that a so-called proximity effect causes a large adverse effect.

That is, the diffracted light beams passing through the adjacent light transmission regions are two-dimensionally arranged so close to each other that they influence each other (interference with each other), and are composed of a plurality of light transmission regions having the same size. In the halftone phase shift mask having the light transmitting area group, the size of the resist pattern formed by the light transmitting area located at the outermost periphery of the light transmitting area group and the position in the other area of the light transmitting area group There is a problem in that the sizes of the resist patterns formed by the light transmitting regions are different.

Assume a halftone type phase shift mask in which the light transmission region group is composed of light transmission regions arranged two-dimensionally in a 3 × 3 matrix and the size of each light transmission region is 0.35 μm. . The distance between the centers of the light transmission regions is 0.75 μm. A schematic plan view of such a halftone type phase shift mask is shown in FIG.
In addition, such a halftone type phase shift mask is
Hereinafter, this is called a conventional halftone phase shift mask. Further, for convenience, the light transmission region located at the center of the light transmission region group is referred to as a light transmission region A, and the light transmission region located at the corner of the outermost periphery of the light transmission region group is referred to as a light transmission region B. A light transmitting area C at a position other than the corner portion of the outermost periphery of the light transmitting area group is referred to as a light transmitting area C.

In the present specification, the display of size and distance is based on the size and distance of the pattern formed on the resist. That is, when the size of the light transmission region is 0.35 μm, the reduction magnification of the reduction optical system of the exposure apparatus is 1
/ 5 times, the size of the light transmission region to be formed in the halftone phase shift mask is 0.35 × 5 = 1.
It is 75 μm. If the distance between the centers of the light transmitting areas is 0.75 μm, the distance between the centers of the light transmitting areas to be formed in the halftone phase shift mask is 0.75 × 5 = 3.75 μm. Is.

Using such a halftone type phase shift mask, when the focus offset value is 0 μm, the light transmission area A shown in FIG.
Exposure is performed with an exposure amount that a circular pattern of m is formed on the resist. When exposure is performed under such conditions, a circular pattern having a diameter of 0.298 μm is formed on the resist by the light transmitting region B shown in FIG. Further, an elliptical pattern having a vertical axis length of 0.300 μm and a horizontal axis length of 0.297 μm is formed on the resist by the light transmission region C shown in FIG.

Here, the focus offset value is defined as follows. That is, when a pattern formed on such a mask in a reduction projection optical system is transferred to a resist by using an ordinary mask composed of a light transmitting area and a light shielding area, which is not a phase shift mask or a halftone type phase shift mask. , The focal length when the sharpest image is obtained on the resist is the focus offset value = 0μ
m. In addition, when moving, for example, a wafer on which a resist is formed from this position in the direction of approaching the halftone phase shift mask, the focus offset value is a value of “+”. On the contrary, when the wafer is moved away from the halftone phase shift mask, the focus offset value is “−”.

On the other hand, the focus offset value is ± 0.7
When the exposure amount was 5 μm and the exposure amount was the same, a circular pattern having a diameter of 0.268 μm was formed on the resist by the light transmitting region A shown in FIG. Further, a circular pattern having a diameter of 0.262 μm was formed on the resist by the light transmitting region B shown in FIG. Further, an elliptical pattern having a vertical axis length of 0.268 μm and a horizontal axis length of 0.266 μm was formed on the resist by the light transmitting region C shown in FIG.

The 0th-order diffracted light passing through the light-transmitting region A located at the center of the light-transmitting region group is influenced by the 1st-order and higher-order diffracted lights passing through the light-transmitting regions C located on all sides (interfering with each other). Fit). On the other hand, the 0th-order diffracted light passing through the light transmitting region B located at the corner of the outermost periphery of the light transmitting region group is
It is affected (interference) by the diffracted light of the first or higher order that passes through the light transmission regions C located on two sides and the effect (interference) by the semi-shielding layers located on two sides. Further, the 0th-order diffracted light passing through the light-transmitting region C has an influence (interference) of the 1st-order and higher-order diffracted light passing through the light-transmitting region B located on two sides and the light-transmitting region A located on one side, and It is affected (interference) by the semi-light-shielding layer 14 located on one side. As a result, a difference occurs in the size of the resist pattern obtained based on each light transmitting region.
Incidentally, depending on the case, it is also affected by the light transmitting region located in the oblique direction.

Depending on the size of the light transmitting area and the distance between the centers of the light transmitting areas, the size of the resist pattern obtained based on the light transmitting area located at the center of the light transmitting area group is It may be smaller than the size of the resist pattern obtained based on the light-transmitting region located at the outermost periphery of the group.

As described above, when the size of the pattern formed on the resist differs depending on the position where the light transmitting region is formed in the light transmitting region group, a fine pattern having a desired size is stabilized. It becomes difficult to form it on the resist. In particular, it becomes more difficult to form a finer pattern on the resist by performing exposure with the focus offset value as a certain value.

Therefore, the first object of the present invention is that the diffracted lights passing through the adjacent light transmitting regions influence each other, that is, the diffracted lights passing through the adjacent light transmitting regions interfere with each other. A halftone phase shift mask in which a light transmission region group composed of light transmission regions arranged in close proximity to each other is formed, and is formed on a resist regardless of the position where each light transmission region is formed. It is an object of the present invention to provide a halftone phase shift mask that can make the size of a pattern to be constant and a resist exposure method using the halftone phase shift mask.

Further, a second object of the present invention is that the diffracted lights passing through the adjacent light transmitting regions affect each other,
That is, as the diffracted light beams passing through the adjacent light transmitting regions interfere with each other, the light transmitting region group composed of the light transmitting regions arranged in close proximity is formed, and the light transmitting regions pass through the isolated light transmitting regions. At a position where the diffracted light and the diffracted light that has passed through the light transmissive region located at the outermost periphery of the light transmissive region group do not interfere with each other,
A halftone phase shift mask in which isolated light transmitting areas are arranged, which makes it possible to make the size of a pattern formed on a resist constant regardless of the position where each light transmitting area is formed. A mask and a resist exposure method using the halftone phase shift mask.

[0022]

A first object of the present invention is to provide a semi-light-shielding layer formed on a transparent substrate, and a light-transmitting region group composed of a plurality of light-transmitting regions. Is a halftone phase shift mask in which the phase of the light passing through and the phase of the light passing through the light transmitting area are different, and the diffracted light passing through the adjacent light transmitting areas interferes with each other so that the light transmitting area group The light transmissive regions are arranged close to each other, and the size of each of the light transmissive regions located at the outermost periphery of the light transmissive region group is the same as the size of the light transmissive regions located in other regions of the light transmissive region group. Can be achieved by the halftone phase shift mask according to the first aspect of the present invention.

Further, the above-mentioned second object consists of a semi-light-shielding layer formed on a transparent substrate, a light transmission region group composed of a plurality of light transmission regions, and an isolated light transmission region.
A halftone phase shift mask in which the phase of light passing through the semi-shielding layer is different from the phase of light passing through the light transmitting area, and the diffracted light passing through the adjacent light transmitting areas interferes with each other, and The light transmitting areas of the light transmitting area group are arranged close to each other, and the diffracted light passing through the isolated light transmitting area does not interfere with the diffracted light passing through the light transmitting area located at the outermost periphery of the light transmitting area group. In the present invention, the isolated light transmitting region is arranged at a position, and the size of the isolated light transmitting region is different from the size of the light transmitting region located at the outermost periphery of the light transmitting region group. This can be achieved by the halftone phase shift mask according to the second aspect.

In the halftone phase shift mask according to the second aspect of the present invention, the size of each light transmission region located at the outermost periphery of the light transmission region group is set to the other region of the light transmission region group. It is desirable that the size is different from the size of the light transmission region located.

The arrangement pattern of the light transmitting region group is 1
XN (where N is an integer of 3 or more), 2xN, MxN '
(However, M and N ′ are integers of 3 or more), a one-dimensional or two-dimensional array pattern can be exemplified. In this case, in the 1 × N array pattern, the first and N
The th light transmissive region is the light transmissive region located at the outermost periphery of the light transmissive region group. On the other hand, the K-th (1 <K <N) light transmissive region is a light transmissive region located in another region of the light transmissive region group. In a 2 × N array pattern, (1,
1) th, (1,2) th, (N, 1) th and (N,
The 2) -th light transmissive region is a light transmissive region located at the outermost periphery of the light transmissive region group. On the other hand, other light transmission area,
The light transmitting area is located in another area of the light transmitting area group.
In the M × N ′ array pattern, the first row, the first column,
The light transmission regions located at the M-th row and the N'th column are the light transmission regions located at the outermost circumference of the light transmission region group. On the other hand, the other light transmissive regions are light transmissive regions located in other regions of the light transmissive region group.

The above-mentioned object is further characterized in that the resist formed on the substrate is exposed by using the halftone type phase shift mask according to the first or second aspect of the present invention. This can be achieved by a resist exposure method.

[0027]

In the halftone phase shift mask according to the first aspect of the present invention, the size of each of the light transmitting regions located at the outermost periphery of the light transmitting region group is the same as that of the other region of the light transmitting region group. The size is different from the size of the light transmission region located.
On the other hand, in the halftone phase shift mask according to the second aspect of the present invention, the size of the isolated light transmission region is different from the size of the light transmission region located at the outermost periphery of the light transmission region group. This makes it possible to form a pattern of substantially uniform size on a resist on a substrate made of a wafer or the like without depending on the arrangement state of the light transmission regions or the semi-shielding layers around each light transmission region.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described based on embodiments with reference to the drawings.

Example 1 Example 1 relates to a halftone phase shift mask according to the first aspect of the present invention. FIG. 1 is a schematic partial plan view, and FIG.
As shown in the schematic partial sectional views of (B) and (C), the halftone phase shift mask of Example 1 is
It is composed of a semi-light-shielding layer 14 formed on a transparent substrate 10 and a light-transmissive region group composed of a plurality of light-transmissive regions 12A, 12B, 12C. The phases of the light passing through the regions 12A, 12B, and 12C are different by 180 degrees, for example. In addition, in FIG.
The light transmissive region is simply designated by the reference numeral 12.

Adjacent light transmitting regions 12A, 12B, 12
The light transmission regions 12A, 12B, and 12C of the light transmission region group are arranged closer to each other so that the diffracted lights passing through C interfere with each other. In the first embodiment, the 3 × 3 light transmission regions 12A, 12B, 12C are two-dimensionally arranged in a matrix. The light transmission region 12A is a light transmission region located at the center of the light transmission region group, and the light transmission region 1
Reference numeral 2B denotes a light transmission area located at a corner portion of the outermost circumference of the light transmission area group, and light transmission area 12C denotes a light transmission area at a position other than the corner portion of the outermost circumference of the light transmission area group. Is.

In the first embodiment, the distance between the centers of the light transmitting areas is 0.75 μm. At such a distance, each of the light transmitting areas 12A, 12B, 1 of the light transmitting area group is
In 2C, the diffracted lights that have passed through the adjacent light transmission regions interfere with each other. Here, diffracted lights interfere with each other when the 0th-order diffracted light that has passed through a certain light-transmitting region and the 1st-order and higher-order diffracted lights that have passed through the light-transmitting region adjacent to this light-transmitting region interfere with each other. Means to do.

The size of each of the light transmitting areas 12B and 12C located at the outermost periphery of the light transmitting area group is made different from the size of the light transmitting area 12A located in the other area of the light transmitting area group. In the first embodiment, the size of the light transmission region 12A is 0.350 μm × 0.350 μm,
The size of B was 0.355 μm × 0.355 μm.
On the other hand, in the light transmitting area 12C, the light transmitting area 12A
The size (length) along the direction toward is 0.355 μm
And the size (length) along the direction toward the light transmission region 12B was 0.350 μm.

By using the halftone phase shift mask of Example 1 as described above, the light transmission region 12A and the light transmission region 1 when the focus offset value is variously changed.
The simulation result of the resist pattern size obtained based on 2B is shown in FIG. As exposure light, Kr
Using F laser light (wavelength: 248 nm), the numerical aperture (NA) of the exposure apparatus is 0.5 and the coherence degree (σ) is 0.5.
And the light intensity transmittance of the semi-shielding layer 14 was set to 10%. Further, when the focus offset value is 0 μm, it is assumed that the light-transmitting region 12A is used to perform exposure with an exposure amount such that a circular pattern having a diameter of 0.30 μm is formed on the resist. When exposing a resist formed on a substrate such as a wafer under such conditions, the focus offset value is ± 0.75μ.
When the distance is m, the diameter is 0.26 due to the light transmitting region 12A.
A circular pattern having a diameter of 8 μm is formed on the resist, a circular pattern having a diameter of 0.270 μm is formed on the resist by the light transmitting area 12B, and a circular pattern having a diameter of 0.272 μm is formed on the resist by the light transmitting area 12C. Was done. That is, a circular pattern having substantially the same diameter could be formed on the resist. Note that FIG. 3 summarizes the results of Example 1 and the results of the conventional halftone phase shift mask (conventional example) described in FIG. 11.

When the focus offset value is 0 μm, a circular pattern having a diameter of 0.300 μm is formed on the resist by the light transmitting region 12A, and the light transmitting region 1
By 2B, a circular pattern having a diameter of 0.304 μm was formed on the resist. The resist pattern formed by the light transmitting region 12B was slightly large, but was well within the allowable range.

Example 2 Example 2 relates to a halftone phase shift mask according to the second aspect of the present invention. FIG. 4 is a schematic partial plan view, and FIG.
As shown in the schematic partial sectional view in (B) or (C), the halftone phase shift mask of the second embodiment is
The phase of the light passing through the semi-shielding layer 14, which is formed on the transparent substrate 10 and includes the semi-shielding layer 14, the light transmitting region group including the plurality of light transmitting regions 12B, and the isolated light transmitting region 30. And the phase of light passing through the light transmission regions 12B and 30 is different by 180 degrees, for example.

The light transmission regions 12B of the light transmission region group are arranged so that the diffracted light beams passing through the adjacent light transmission regions 12B are close enough to interfere with each other. In the second embodiment, the 2 × 2 light transmission regions 12B are two-dimensionally arranged in a matrix. Incidentally, these light transmitting regions 12B
Are all the outermost circumferences of the light transmitting area group and the light transmitting areas located at the corners. In Example 2,
The distance between the centers of the light transmitting regions was 0.75 μm. At such a distance, the diffracted lights that have passed through the respective light transmission regions 12B of the light transmission region group interfere with each other.

On the other hand, the diffracted light that has passed through the isolated light transmission region 30 and the light transmission region 1 located at the outermost periphery of the light transmission region group.
The isolated light transmission region 30 is arranged at a position where it does not interfere with the diffracted light that has passed through 2B. Specifically, the distance between the centers of the light transmission regions 12B ′ in the closest light transmission region group and the isolated light transmission regions 30 is 1.5 μm or more. Here, the fact that the diffracted light passing through the isolated light transmitting region and the diffracted light passing through the light transmitting region located at the outermost periphery of the light transmitting region group do not interfere means that the 0th order passing through the isolated light transmitting region 30. Diffracted light and this isolated light transmission region 30
The diffracted lights of the first and higher orders that have passed through the light transmission region 12B ′ adjacent to the
It means that the diffracted light of the 1st or more order that has passed through and the diffracted light of the 0th order that has passed through the light transmission region 12B ′ adjacent to the isolated light transmission region 30 do not interfere with each other.

The size of the isolated light transmitting region 30 is set to the light transmitting region 12B located at the outermost periphery of the light transmitting region group.
Different from the size of. In the second embodiment, the size of the light transmission region 12B is 0.350 μm × 0.350 μm, and the size of the light transmission region 30 is 0.355 μm × 0.3.
It was set to 55 μm. In the second embodiment, since the light transmission regions 12B forming the light transmission region group are arranged in a 2 × 2 matrix, each light transmission region is equally affected by the other light transmission regions. Therefore, all the light transmitting regions 12B have the same size.

The pattern size of the resist obtained based on the light transmission region 12B and the isolated light transmission region 30 when the focus offset value is variously changed by using the halftone type phase shift mask of the second embodiment. The result of the simulation is shown in FIG. It is assumed that when the focus offset value is 0 μm, exposure is performed with an exposure amount such that the light-transmitting region 12B forms a circular pattern having a diameter of 0.30 μm on the resist. When exposing under such conditions, the focus offset value is ± 0.70μ
When m, the diameter is 0.268μ due to the light transmitting region 12B.
A circular pattern of m was formed on the resist. on the other hand,
A circular pattern having a diameter of 0.272 μm was formed on the resist by the isolated light transmitting regions 30. That is, a circular pattern having substantially the same diameter could be formed on the resist.

When the focus offset value is 0 μm, a circular pattern having a diameter of 0.300 μm is formed on the resist by the light transmitting region 12B, and a circular pattern having a diameter of 0.303 μm is formed by the isolated light transmitting region 30. Formed on the resist. Although the resist pattern formed by the light transmitting region 12B is slightly large,
It was well within the allowable range.

For comparison, the size of the isolated light transmitting region 30 was set to 0.350 μm × 0.350 μm. That is, the sizes of all the light transmission regions including the isolated light transmission region 30 are made the same. In this case, when the focus offset value was ± 0.70 μm, a circular pattern having a diameter of 0.268 μm was formed on the resist by the light transmitting region 12B. On the other hand, a small circular pattern having a diameter of 0.263 μm was formed on the resist by the isolated light transmitting region 30.

Example 3 Example 3 is a modification of Example 2 and relates to a combination of Example 1 and Example 2. In the third embodiment, as shown in the plan view of FIG. 6, the light transmitting region groups are arranged in a 3 × 3 two-dimensional matrix. Further, an isolated light transmission region 30 is arranged. Light Transmission Regions 12A and 12 that constitute a light transmission region group
The arrangement and size of B and 12C were the same as in Example 1. On the other hand, in Example 3, the isolated light transmitting region 3
The isolated light transmitting region 30 is arranged at a position where the diffracted light passing through 0 and the diffracted light passing through the light transmitting region located at the outermost periphery of the light transmitting region group do not interfere with each other. In particular,
The distance between the centers of the light transmission regions 12C ′ in the closest light transmission region group and the isolated light transmission regions 30 is 1.5 μm or more. The size of the isolated light transmitting region 30 is similar to that in the second embodiment.

When a pattern was formed on the resist by using the halftone type phase shift mask of Example 3 as described above, the same pattern size as described in Examples 1 and 2 could be obtained.

An outline of the method of manufacturing the halftone phase shift mask will be described below.

A process of manufacturing the halftone type phase shift mask shown in FIG. 7A will be described below with reference to FIG. First, the substrate 1 made of a transparent material such as quartz
A phase shift layer 20 made of, for example, SOG (Spin On Glass) is formed on the surface of No. 0 by a coating method. Considering the phase difference due to the semi-shielding layer and the phase shift at each layer interface, the thickness d of the phase shift layer 20 is the difference between the phase of the light passing through the light transmitting region 12 and the phase of the light passing through the semi-shielding layer 14. Is 1
It was decided to be 80 degrees. As a result, next, the semi-light-shielding layer 14 made of chromium and having a thickness of 22 nm is formed on the phase shift layer 20 by the sputtering method (see FIG. 8A). KrF excimer laser light (wavelength: 248n
When m) is used as the exposure light, the light intensity transmittance of the semi-shielding layer 14 having such a thickness is 10%. Generally, the semi-shielding layer 14 has a light intensity transmittance of, for example, 4 to 20%.
Select the thickness of. Next, for example, a positive resist 40 is formed on the semi-light-shielding layer 14 by a coating method. Then, the electron beam is applied to the positive resist 40 above the portion where the light transmitting region is to be formed, and the positive resist 40 is developed (see FIG. 8B). After that, the semi-light-shielding layer 14 made of chromium is dry-etched in plasma with a mixed gas of chlorine and oxygen (see FIG. 8C), and further, from SOG in plasma with a mixed gas of carbon tetrafluoride and oxygen. The resulting phase shift layer 20 is etched, and finally the positive resist 40 is removed. Thus, the halftone phase shift mask shown in FIG. 7A can be manufactured.

The step of manufacturing the halftone phase shift mask shown in FIG. 7B is basically the same as the method of manufacturing the halftone phase shift mask shown in FIG. 7A. The same can be applied except that the order of steps is different. That is, as shown in FIG. 9A, first,
A semi-light-shielding layer 14 made of chromium is formed on a surface of a substrate 10 made of a transparent material such as quartz by a sputtering method, and then a phase shift layer 20 made of, for example, SOG is formed thereon.
Is formed by a coating method. Then, for example, a positive resist 40 is formed on the phase shift layer 20 by a coating method. Then, the electron beam is applied to the positive resist 40 above the portion where the light transmission region is to be formed, and the positive resist 40 is developed (see FIG. 9B). After that, the phase shift layer 20 made of SOG is etched in the plasma with the mixed gas of carbon tetrafluoride and oxygen (see FIG. 9C), and the semi-light-shielding layer made of chromium in the plasma with the mixed gas of chlorine and oxygen. 14 is dry-etched, and finally the positive resist 40 is removed. Thus, the halftone type phase shift mask shown in FIG. 7B can be manufactured.

A process of manufacturing the substrate digging type halftone phase shift mask shown in FIG. 7C will be described below with reference to FIG. First, for example, a thickness of 22 nm is formed on the surface of the substrate 10 made of a transparent material such as quartz.
The semi-light-shielding layer 14 made of chromium is formed by the sputtering method. Next, a positive resist 40, for example, is formed on the semi-light-shielding layer 14 by a coating method (see FIG. 10A). Then, the electron beam is applied to the positive resist 40 above the portion where the light transmitting region is to be formed, and the positive resist 40 is developed (see FIG. 10B). After that, the semi-light-shielding layer 14 made of chromium is dry-etched in plasma with a mixed gas of chlorine and oxygen (see FIG.
(See (C)), and further, the substrate 10 is etched in plasma with a mixed gas of carbon tetrafluoride and oxygen, and finally the positive resist 40 is removed. Thus, the halftone type phase shift mask shown in FIG. 7C can be manufactured.

The present invention has been described above based on the preferred embodiments, but the present invention is not limited to these embodiments. Various numerical values described in the examples, the size and arrangement / arrangement of the light transmission region, the phase difference, etc. are examples, and as appropriate,
It can be changed to a desired value or an appropriate value. The arrangement of the light transmissive regions in the light transmissive region group is not limited to a matrix, and for example, in order to form contact holes arranged at equal intervals, the light transmissive regions are arranged two-dimensionally in a zigzag pattern, or in addition, It can be changed appropriately.

When the sizes of the light transmitting areas constituting the light transmitting area group or the isolated light transmitting areas are made equal, the size of the resist pattern obtained based on the light transmitting areas located at the outermost periphery of the light transmitting area group. Is smaller than the size of the resist pattern obtained based on the light transmitting regions located in other regions of the light transmitting region group, and the size of the resist pattern obtained based on the isolated light transmitting regions is When the size of the resist pattern obtained based on the light-transmitting regions located at the outermost periphery of the group is smaller than the size of the resist pattern, the size of each light-transmitting region is generally set as follows. For the sake of convenience, the size of the light transmission region that is not located at the outermost periphery of the light transmission region group (that is, located in the other region) is considered as a reference.

For example, referring to the light transmitting region group shown in FIG. 1, the light transmitting region 1 located at the center of the light transmitting region group.
The 0th-order diffracted light passing through 2A has an influence (interference) of the 1st-order and higher-order diffracted lights passing through the light transmission regions 12C located on all sides
Receive. Therefore, the bias amount of the light transmitting region 12A is
The light-transmitting region forming the light-transmitting region group is made the smallest. On the other hand, the 0th-order diffracted light that passes through the light-transmitting regions 12B located at the corners of the outermost circumference of the light-transmitting region group is a diffracted light of the 1st-order or more that passes through the light-transmitting regions 12C located on two sides. It is affected (interference) and the semi-light-shielding layers located on two sides (interference). Therefore, the bias amount of the light transmission region 12B is made larger than the bias amount of the light transmission region 12A. Further, the 0th-order diffracted light passing through the light-transmitting region 12C has an influence (interference) of the 1st-order or more diffracted light passing through the light-transmitting region 12B located on two sides and the light-transmitting region 12A located on one side, and It is affected (interference) by the semi-light-shielding layer 14 located on one side. Therefore, the bias amount of the light transmission region 12C along the direction from the light transmission region 12C to the light transmission region 12A is set to be about the bias amount of the light transmission region 12B. On the other hand, the bias amount of the light transmission region 12C along the direction from the light transmission region 12C to the light transmission region 12B is set to be about the bias amount of the light transmission region 12A. The isolated light transmitting region 30 is affected by the light passing through the semi-shielding layers 14 located on all sides. Therefore, regarding the isolated light transmitting region 30, for example, the light transmitting region 12 shown in FIG.
The bias amount is similar to B. However, these bias amounts are a kind of guideline, and it is necessary to actually perform various simulations and tests to determine the optimum bias amount for each light transmission region. Depending on the case, it is necessary to consider the influence of the light transmission region located in the diagonal direction.

Depending on the size of the light transmissive regions and the distance between the centers of the light transmissive regions, the size of the resist pattern obtained based on the light transmissive regions located in the center of the light transmissive regions may be different from that of the light transmissive regions. It may be smaller than the size of the resist pattern obtained based on the light transmissive region located at the outermost periphery. In this case, the relationship of the bias amount of the light transmitting area may be reversed.

Various materials used in the manufacturing process of the halftone phase shift mask can be appropriately changed. The substrate 10 can be made of not only quartz but also ordinary glass, glass to which various components are appropriately added, and the like. The material forming the semi-light-shielding layer 14 is not limited to chromium, but chromium oxide, chromium oxide laminated on chromium, refractory metal (W, Mo, Be, etc.), tantalum, aluminum, or M.
It is possible to use a material capable of blocking an appropriate amount of light, such as metal silicide such as oSi ₂ . Further, the phase shift layer 20 is made of polymethylmethacrylate, magnesium fluoride, titanium dioxide, polyimide resin, silicon dioxide, indium oxide, S instead of being composed of SOG.
Any transparent material such as iN and various resists may be used. A negative resist may be used instead of the positive resist.
In this case, the electron beam drawing area is different from that of the positive type resist.

[0053]

In the halftone phase shift mask of the present invention, a pattern of substantially uniform size is formed on a wafer or the like without depending on the arrangement state of the light transmission region or the semi-shielding layer around each light transmission region. Can be formed in a resist on a substrate consisting of. Moreover, since a fine pattern having a substantially uniform size can be formed on a resist on a substrate such as a wafer with a predetermined focus offset amount, it is possible to improve the depth of focus of the entire halftone phase shift mask. You can

[Brief description of drawings]

FIG. 1 is a schematic plan view of a halftone phase shift mask of Example 1.

FIG. 2 is a diagram showing a simulation result of a resist pattern size when the halftone phase shift mask of Example 1 is used.

FIG. 3 is a diagram summarizing resist pattern sizes in Example 1 and a conventional halftone phase shift mask.

FIG. 4 is a schematic plan view of a halftone phase shift mask of Example 2.

FIG. 5 is a diagram showing a simulation result of a resist pattern size when the halftone phase shift mask of Example 2 is used.

FIG. 6 is a schematic plan view of a halftone phase shift mask of Example 3.

FIG. 7 is a schematic partial cross-sectional view of various halftone phase shift masks.

FIG. 8 is a diagram for explaining a manufacturing process of the halftone phase shift mask shown in FIG. 7 (A).

FIG. 9 is a diagram for explaining a manufacturing process of the halftone phase shift mask shown in FIG. 7B.

FIG. 10 is a diagram for explaining a manufacturing process of the halftone phase shift mask shown in FIG. 7C.

FIG. 11 is a schematic partial plan view of a conventional halftone phase shift mask.

FIG. 12 is a schematic partial cutaway view of a typical conventional edge enhancement type phase shift mask.

[Explanation of symbols]

 10 Substrate 12, 12A, 12B, 12C Light Transmission Region 14 Semi-shielding Layer 20 Phase Shift Layer 30 Isolated Light Transmission Region

Claims (4)

[Claims] 1. A light-transmitting region group formed of a semi-light-shielding layer and a plurality of light-transmitting regions formed on a transparent substrate, wherein a phase of light passing through the semi-light-shielding layer and a light-transmitting region are passed. This is a halftone phase shift mask with different light phases, and the light transmission areas of the light transmission area group are arranged closer to each other so that the diffracted light passing through the adjacent light transmission areas interferes with each other. The size of each of the light transmitting areas located at the outermost periphery of the light transmitting area group is different from the size of the light transmitting areas located in other areas of the light transmitting area group. Shift mask. 2. A phase of light passing through the semi-shielding layer, which is formed of a semi-shielding layer, a light-transmitting region group composed of a plurality of light-transmitting regions, and an isolated light-transmitting region formed on a transparent substrate. Is a halftone phase shift mask in which the phases of the light passing through the light transmitting area are different from each other, and as the diffracted light passing through the adjacent light transmitting areas interferes with each other, The isolated light transmitting areas are arranged in close proximity to each other at a position where the diffracted light passing through the isolated light transmitting areas and the diffracted light passing through the light transmitting areas located at the outermost periphery of the light transmitting area group do not interfere with each other. The halftone phase shift mask, wherein the size of the isolated light transmitting area is different from the size of the light transmitting area located at the outermost periphery of the light transmitting area group. 3. The size of each of the light transmitting areas located at the outermost periphery of the light transmitting area group is different from the size of the light transmitting areas located in other areas of the light transmitting area group. Item 2. The halftone phase shift mask according to Item 2. 4. A halftone phase shift mask according to claim 1, wherein:
A resist exposure method, which comprises exposing a resist formed on a substrate.