JPH0844039A - Phase shift mask of halftone system and resist exposing method - Google Patents

Abstract

PURPOSE:To provide alone a phase shift mask of halftone system capable of making the size of resist patterns formed on a resist constant as far as possible regardless of positions where respective light transmission regions are formed. CONSTITUTION:This phase shift mask consists of light transmission region groups composed of a semi-light shielding layer and plural light transmission regions formed on a transparent substrate. The phase of the light past the semi-light shielding layer and the phase of the light past the light transmission regions vary. The respective light transmission regions of the light transmission region groups are arranged in proximity to the extent that the diffracted light rays past the adjacent light transmission regions 12A, 12B, 12C interfere with each other. The light transmission regions 12B, 12C existing on the outermost periphery of the light transmission region groups are provided with auxiliary light transmission regions 40 in their respective neighborhood.

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. Unless otherwise specified, the resist pattern means a pattern formed on the resist when the pattern shape on the photomask is transferred to the resist formed on the substrate made of a wafer, for example.

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, in place of such a conventional photomask, a phase shift region for changing the phase of light is provided.
So-called phase shift masks have come to be used. By using a phase shift mask, it is possible to form a fine resist 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. Typical partial cutaway views of a typical conventional edge-enhanced phase shift mask are shown in FIGS. 15 (A), (B) and (C). 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 resist 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 above problems of the conventional phase shift mask, the phase and the light transmission of the light passing through the semi-light shielding layer are constituted by a semi-light shielding 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.

A schematic partial cutaway view of the halftone phase shift mask is shown in FIGS. 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 such as SOG (Spin On Glass) for making the phase of the light passing through the light transmitting region 12 different from the phase of the light passing through the semi-shielding layer 14. In this case, the thickness of the phase shift layer 20 is set in consideration of the phase difference due to the semi-light-shielding layer 14 and the phase shift at each layer interface, and the light transmission region 1
The difference between the phase of light passing through 2 and the phase of light passing through the semi-shielding layer 14 is determined to be 180 degrees. Alternatively, the halftone type phase shift mask shown in FIG. 12C 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, in consideration of the phase difference due to the semi-light-shielding layer 14 and the phase shift at each layer interface, the depth of the concave portion 16 and the phase of the light passing through the light-transmitting region 12 and the light passing through the semi-light-shielding layer 14 are taken into consideration. The phase difference is determined to be 180 degrees.

In the halftone phase shift mask, the amplitude transmittance of the semi-light-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. Usually, 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 a resist to form a resist pattern, the light passing through the semi-shielding layer 14 having a predetermined light intensity transmittance and a phase, The interference of the light passing through the light transmitting region 12 different from the 180 degree semi-shielding layer is used.

[0009]

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, a group of light transmitting areas composed of a plurality of light transmitting areas which are two-dimensionally arranged close to each other so that the diffracted lights passing through the adjacent light transmitting areas interfere with each other, and are arranged in a two-dimensional manner. In the halftone phase shift mask having, the size of the resist pattern formed by the light transmissive region located at the outermost periphery of the light transmissive region group and the light transmissive region formed by the other region of the light transmissive region group are formed. Another problem is that the resist patterns have different sizes.

Assume a halftone phase shift mask in which a group of light transmissive regions are two-dimensionally arranged in a matrix of 5 × 5 and the size of each light transmissive region is 0.38 μm. . The distance between the centers of the light transmission regions is set to 0.60 μm. This halftone type phase shift mask is for forming a contact hole. FIG. 13 is a schematic plan view of this halftone type phase shift mask.
Shown in Incidentally, such a halftone type phase shift mask will be hereinafter referred to as a conventional halftone type phase shift mask or a conventional example. For the sake of convenience, the light transmissive regions located at the corners of the outermost periphery of the light transmissive regions are referred to as light transmissive regions B, and the light transmissive regions located at positions other than the corners of the outermost perimeters of the light transmissive regions. Is called a light transmission region C,
The light transmissive region located in the other region is called a light transmissive region A. In addition, the light transmission region located in the other region may be referred to as a light transmission region located in the center of the light transmission region group.

In this specification, the display of size and distance is
The size and distance of the pattern formed on the resist are used as a reference. That is, when the size of the light transmission region is 0.38 μm, the reduction magnification of the reduction optical system of the exposure apparatus is 1/5.
If it is doubled, the size of the light transmission region to be formed in the halftone phase shift mask is 0.38 × 5 = 1.90.
μm. Further, the distance between the centers of the respective light transmission regions is 0.
If it is 60 μm, the distance between the centers of the light transmission regions to be formed in the halftone phase shift mask is
0.60 × 5 = 3.00 μm.

Using the following halftone type phase shift mask for forming a contact hole having the following specifications, a light intensity simulation was performed under the following exposure conditions. Size of light transmissive area: 0.38 μm Number of light transmissive areas: 5 × 5 Distance between centers of light transmissive areas: 0.6 μm Light intensity transmittance of semi-shielding layer: 10% Wavelength of exposure light: 248 nm (KrF Laser light) Numerical aperture (NA) of exposure apparatus: 0.42 Coherence degree (σ): 0.3 Focus offset value: 0.6 μm Note that the coherence degree (σ) is 0 so that the influence of interference is intentionally increased. Was set to 3. The result of the light intensity simulation is shown in FIG. From this result, the diameter of the resist pattern formed on the resist (contact hole diameter) was determined. The diameter of the resist pattern corresponding to the light transmitting area A was 0.304 μm, and the diameter of the resist pattern corresponding to the light transmitting area B was calculated. Was 0.348 μm. That is, the diameter of the resist pattern corresponding to the light-transmitting region located at the corner of the outermost periphery of the light-transmitting region group is expanded by 0.04 μm or more.

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 resist pattern is formed is set as the focus offset value = 0 μm. 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 “−”.

The chemically amplified positive resist actually formed on the wafer was exposed under the following halftone type phase shift mask for forming contact holes and exposure conditions. Size of light transmission area: 0.37 μm Number of light transmission areas: 9 × 9 Distance between centers of light transmission areas: 0.6 μm Light intensity transmittance of semi-shielding layer: 10% Wavelength of exposure light: 248 nm (KrF Laser light) Numerical aperture (NA) of exposure apparatus: 0.42 Coherence degree (σ): 0.5 Focus offset value: 0.6 μm

After the resist was developed, the shape of the opening formed in the resist was observed by SEM. As a result, the opening was formed in the resist portion corresponding to the outermost circumference (light transmitting areas B and C) of the light transmitting area group. Although a portion was formed, an opening having a desired shape was not formed in the resist portion corresponding to the light transmitting area (light transmitting area A) located at the center of the light transmitting area group. When a similar test was conducted with the size of the light transmission region being 0.38 μm, in particular, the light transmission region A was formed in the portion of the resist corresponding to the outermost corner portion (light transmission region B) of the light transmission region group. A large opening was formed in comparison with.

The 0th-order diffracted light passing through the light-transmitting area A located at the center of the light-transmitting area group interferes with the 1st-order or more diffracted light passing through the light-transmitting areas C located on all sides. on the other hand,
The 0th-order diffracted light passing through the light-transmitting regions B located at the corners of the outermost periphery of the light-transmitting region group is the first-order or higher-order diffracted light passing through the light-transmitting regions C located at the two sides, and They interfere with the light passing through the semi-light-shielding layer located on the other side. Further, the 0th-order diffracted light passing through the light transmitting region C interferes with the 1st or more diffracted light passing through the light transmitting region B located on two sides and the light transmitting region A located on one side, and further, , And interfere with the light passing through the semi-shielding layer 14 located on one side.

As described above, the 0th-order diffracted light passing through the light transmitting region B and the light transmitting region C interferes with the light passing through the adjacent semi-shielding layer 14. As a result, the pattern images obtained from the light transmitting regions B and C have a higher contrast than the pattern images obtained from the light transmitting region A. That is, a sharp resist pattern can be formed. On the other hand, the 0th-order diffracted light passing through the light transmission region A interferes with the 1st-order or more diffracted light passing through the light transmission regions C located on all four sides. Therefore, the contrast of the pattern image based on the light transmissive region A becomes low under the exposure condition where a sharp resist pattern can be formed based on the light transmissive regions B and C, and the resist portion corresponding to the light transmissive region A has a desired shape. No opening is formed.

Depending on the size of the light transmitting area, the distance between the centers of the light transmitting areas, or the exposure conditions, the size of the resist pattern obtained based on the light transmitting area A located at the center of the light transmitting area group may be different. The size of the resist pattern obtained based on the light transmitting regions B and C located at the outermost periphery of the light transmitting region group may be larger than the size of the resist pattern.

As described above, when the size of the resist pattern formed on the resist varies 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. Then, it becomes difficult to form 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. (EN) Provided are a halftone phase shift mask capable of making the size of a resist pattern as constant as possible, and a resist exposure method using such a halftone phase shift mask.

Further, a second object of the present invention is that the diffracted lights passing through the adjacent light transmitting regions influence 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 resist pattern formed on a resist as constant as possible regardless of the position where each light transmitting area is formed. A phase shift mask and a resist exposure method using the halftone phase shift mask.

[0023]

A halftone phase shift mask according to a first aspect of the present invention for achieving the above first object is a semi-shielding layer formed on a transparent substrate, And a half-tone phase shift mask composed of a light-transmitting region group composed of a plurality of light-transmitting regions, wherein the phase of light passing through the semi-light-shielding layer and the phase of light passing through the light-transmitting region are different, and are adjacent to each other. As the diffracted lights passing through the light transmission regions interfere with each other, the respective light transmission regions of the light transmission region group are arranged closer to each other, and each of the light transmission regions located at the outermost periphery of the light transmission region group is The auxiliary light transmitting region is provided in the vicinity.

Here, the vicinity of the light transmissive region located at the outermost periphery of the light transmissive region group means a region of the halftone phase shift mask in which the light transmissive region group is not formed. More specifically, it means a region outside the light transmitting region group. Therefore, the auxiliary light transmission region is not provided at a position where the light transmission regions face each other with the auxiliary light transmission region interposed therebetween.

In the halftone phase shift mask according to the first aspect of the present invention, an auxiliary light shielding area may be provided instead of the auxiliary light transmitting area.

A halftone phase shift mask according to a second aspect of the present invention for achieving the above-mentioned second object comprises a semi-shielding layer and a plurality of light transmitting regions formed on a transparent substrate. A halftone phase shift mask composed of a group of configured light transmitting regions and an isolated light transmitting region, in which the phase of light passing through the semi-shielding layer and the phase of light passing through the light transmitting region are different, and are adjacent to each other. As the diffracted light passing through the light transmitting region interferes with each other, the light transmitting regions of the light transmitting region group are arranged closer to each other, and the diffracted light passing through the isolated light transmitting region and the light transmitting region group are separated from each other. The isolated light transmission area is arranged at a position where it does not interfere with the diffracted light that has passed through the light transmission area located on the outermost periphery, and the auxiliary light transmission area is provided near the isolated light transmission area. Is characterized by.

In the halftone phase shift mask according to the second aspect of the present invention, an auxiliary light transmission area may be provided near each of the light transmission areas located at the outermost periphery of the light transmission area group. Further, an auxiliary light shielding region may be provided instead of the auxiliary light transmitting region.

The auxiliary light shielding region can be made of carbon, for example.

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 resist exposure method of the present invention for achieving the above object is characterized in that the resist formed on the substrate is exposed using the halftone phase shift mask of the present invention described above.

[0031]

In the halftone phase shift mask according to the first aspect of the present invention, auxiliary light transmission areas are provided in the vicinity of the light transmission areas located at the outermost periphery of the light transmission area group. As a result, the 0th-order diffracted light passing through the light-transmitting regions located at the outermost periphery of the light-transmitting region group interferes with the 1st-order or more diffracted lights passing through the auxiliary light-transmitting region and the surrounding light-transmitting regions. On the other hand, the 0th-order diffracted light that passes through the light transmission regions located at positions other than the outermost periphery interferes with the 1st or higher-order diffracted lights that pass through the surrounding light transmission regions. Second of the present invention
In the halftone phase shift mask according to the above aspect, the auxiliary light transmission region is provided in the vicinity of the isolated light transmission region. As a result, the 0th-order diffracted light passing through the isolated light transmission region interferes with the 1st-order or more diffracted light passing through the auxiliary light transmission region.

Therefore, it becomes possible to make the contrast of the pattern image obtained on the basis of each light transmitting region substantially constant. As a result, a resist pattern based on the light-transmitting region having a substantially uniform size is formed on the resist on the substrate such as a wafer without depending on the arrangement state of the light-transmitting region or the semi-shielding layer around each light-transmitting region. can do.

When the auxiliary light transmitting region is replaced with the auxiliary light shielding region, the phase shift action does not work between the auxiliary light shielding region and the light transmitting region in the vicinity thereof, and the contrast of the pattern image obtained based on the light transmitting region is increased. , And the contrast of the pattern image obtained based on the light transmission region where the phase shift effect extends can be made substantially equal.
As a result, a resist pattern based on the light-transmitting region having a substantially uniform size is formed on the resist on the substrate such as a wafer without depending on the arrangement state of the light-transmitting region or the semi-shielding layer around each light-transmitting region. can do.

[0034]

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

(Embodiment 1) The halftone phase shift mask of Embodiment 1 is for forming a contact hole,
A light transmission region group including 5 × 5 light transmission regions is formed. Other specifications are as follows. Size of light transmission area: 0.38 μm Number of light transmission areas: 5 × 5 Distance between centers of light transmission areas: 0.6 μm Light intensity transmittance of semi-shielding layer: 10%

The halftone phase shift mask of Example 1 is formed on a transparent substrate 10 as shown in a schematic partial plan view in FIG. 1 and a schematic partial cutaway view in FIG. The formed semi-light-shielding layer 14 and the plurality of light transmission regions 12 are formed.
It is composed of a group of light transmitting regions composed of A, 12B and 12C, and the phase of light passing through the semi-shielding layer 14 and the phase of light passing through the light transmitting region are different.

Adjacent light transmitting areas 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 5 × 5 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 regions is set to 0.6 μm. At such a distance, each of the light transmitting areas 12A, 12B, 12 of the light transmitting area group is
In C, 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.

In the first embodiment, the auxiliary light transmitting region 40
In the outermost circumference of the light transmission region group, two are provided outside the light transmission region 12B located at the corner portion, and two are provided at a total of eight locations. The size of each auxiliary light transmission region 40 is 0.38 μm in length and 0.10 μm in width. The distance from the center of the auxiliary light transmission region 40 to the center of the light transmission region 12B was set to 0.60 μm.

A schematic partial cutaway view of the halftone phase shift mask of Example 1 is shown in FIG. Figure 2 (A)
Reference numerals 10 and (B) in FIG. 3 indicate a substrate, 12 a light transmitting region, 14 a semi-light-shielding layer, and 40 an auxiliary light transmitting region.
A phase shift layer 20 is formed below or above the semi-shielding layer 14. The phase shift layer 20 includes the light transmission region 12
And a light-transmitting material, such as SOG, for making the phase of light passing through the auxiliary light transmitting region 40 different from the phase of light passing through the semi-shielding layer 14. In this case, in consideration of the phase difference due to the semi-light-shielding layer 14 and the phase shift at each layer interface, the thickness of the phase shift layer 20 is set to the phase of light passing through the light transmission region 12 and the auxiliary light transmission region 40, Semi-shield layer 14
It is determined that the phase difference of the light passing through is 180 degrees. Alternatively, the halftone type phase shift mask shown in FIG. 2C is a so-called substrate digging type. By forming the concave portion 16 in the substrate 10, the phase of the light passing through the light transmitting region 12 and the auxiliary light transmitting region 40 and the phase of the light passing through the semi-shielding layer 14 can be made different. In this case, the depth of the concave portion 16 is set in consideration of the phase difference due to the semi-light-shielding layer 14 and the phase shift at each layer interface,
The difference between the phase of light passing through the light transmitting region 12 and the auxiliary light transmitting region 40 and the phase of light passing through the semi-shielding layer 14 is 180.
Determine to be the degree.

The result of the light intensity simulation using the halftone phase shift mask of Example 1 is shown in FIG. The exposure conditions were as follows. Wavelength of exposure light: 248 nm (KrF laser light) Numerical aperture (NA) of exposure apparatus: 0.42 Coherence degree (σ): 0.3 Focus offset value: 0.6 μm

From the result of this simulation, the diameter of the resist pattern (contact hole diameter) was calculated.
Diameter of resist pattern corresponding to light transmitting area A (D _A )
Was 0.304 μm, and the diameter (D _B ) of the resist pattern corresponding to the light transmitting region B was 0.328 μm. The diameter of the resist pattern corresponding to the light transmitting region B in the case of the conventional example having no auxiliary light transmitting region was 0.348 μm. From this result, the value of D _B / D _A becomes: Example 1: 1.079 Conventional example: 1.145, which shows that the resist pattern corresponding to the diameter of the resist pattern corresponding to the light transmitting area A corresponds to the diameter of the resist pattern corresponding to the light transmitting area A. It has been found that the expansion of the diameter can be reduced to about 1/2 as compared with the conventional example.

In the conventional example, there is a large difference between the degree of interference received by the light transmission region B from other light transmission regions and the degree of interference received by the light transmission region A from other light transmission regions. Therefore, the diameter of the resist pattern corresponding to the light transmissive region B greatly expands with respect to the diameter of the resist pattern corresponding to the light transmissive region A. On the other hand, in the halftone phase shift mask of the present invention, since the auxiliary light transmissive region 40 exists, the degree of interference that the light transmissive region B receives from other light transmissive regions and the light transmissive region A to other light. The difference in the degree of interference received from the transmission region is reduced. As a result, the light transmission area A
The light transmitting area B corresponding to the diameter of the resist pattern corresponding to
The expansion of the diameter of the resist pattern corresponding to can be reduced.

A resist was formed on a substrate made of an insulating layer formed on a silicon semiconductor substrate, and the resist was exposed using the halftone phase shift mask for forming contact holes described in Example 1. afterwards,
When the resist was developed and the openings formed in the resist were evaluated, it was possible to form openings having substantially the same diameter without depending on the arrangement state of the light transmission areas around each light transmission area.

(Embodiment 2) In the embodiment 1, the diameter of the resist pattern corresponding to the light transmitting area B is enlarged by about 1/2 of the diameter of the resist pattern corresponding to the light transmitting area A as compared with the conventional example. Although it can be reduced to, it is not yet fully satisfactory. Further, forming the auxiliary light transmitting region having a width of only 0.1 μm is a heavy burden in the manufacturing process of the halftone phase shift mask.

In the second embodiment, the auxiliary light transmitting region 40
The width was 0.2 μm and the length was 0.38 μm, and the center-to-center distance between the light transmission region 12B and the auxiliary light transmission region 40 was 0.6 μm. Except for this point, the halftone phase shift mask of Example 2 is the same as that of Example 1.
The result of light intensity simulation using the halftone phase shift mask of Example 2 is shown in FIG. The exposure conditions are the same as in Example 1.

From the result of this simulation, the diameter of the resist pattern (contact hole diameter) was calculated.
Diameter of resist pattern corresponding to light transmitting area A (D _A )
Was 0.304 μm, and the diameter (D _B ) of the resist pattern corresponding to the light transmitting region B was 0.317 μm. That is,
The value of D _B / D _A was 1.043, and it was found that the enlargement of the diameter of the resist pattern can be further reduced as compared with the value (1.079) in Example 1.

(Embodiment 3) In Embodiment 1 and Embodiment 2, the auxiliary light transmitting region 40 having the same structure as the light transmitting region is provided in each of the light transmitting regions located at the outermost periphery of the light transmitting region group. It was provided in the vicinity. On the other hand, in the third embodiment, instead of the auxiliary light transmission region 40, the auxiliary light shielding region 42 is provided near each of the light transmission regions located on the outermost periphery of the light transmission region group. The auxiliary light-shielding region 42 is composed of a layer in which carbon is deposited, and the light intensity transmittance is almost 0%. In the third embodiment, the auxiliary light-shielding excess region 42 is located at the corner portion of the outermost periphery of the light-transmitting region group.
Two pieces are provided on the outside of B, for a total of eight locations.

In the third embodiment, the size of the auxiliary light shielding region 42 is 0.40 μm in width and 0.50 μm in length, and the center distance between the light transmitting region 12B and the auxiliary light shielding region 42 is 0.60.
μm. Except for this point, the halftone phase shift mask of Example 3 is the same as that of Example 1. A schematic plan view of a halftone phase shift mask of Example 3 is shown in FIG. 5, and a partial cutaway view is shown in FIG. The result of the light intensity simulation using the halftone phase shift mask of Example 3 is shown in FIG. The exposure conditions are the same as in Example 1.

From the results of this simulation, the diameter of the resist pattern (contact hole diameter) was calculated.
Diameter of resist pattern corresponding to light transmitting area A (D _A )
Was 0.304 μm, and the diameter (D _B ) of the resist pattern corresponding to the light transmitting region B was 0.324 μm. That is,
The value of D _B / D _A was 1.066, and it was found that the enlargement of the diameter of the resist pattern can be reduced similarly to the values in Examples 1 and 2.

By providing the auxiliary light shielding region 42,
The light transmission region B is partially not subjected to the phase shift action. As a result, the contrast of the pattern image formed based on the light transmission region B is lowered. If this decrease in contrast is approximately equal to the decrease in the contrast of the pattern image that occurs as a result of the interference of the light transmitting area A from other light transmitting areas, the light transmitting area corresponding to the diameter of the resist pattern corresponding to the light transmitting area A will be described. The increase in the diameter of the resist pattern corresponding to B can be reduced. Although the number of steps of manufacturing the halftone phase shift mask is increased as compared with the case where the auxiliary light transmitting region 40 is formed, the problem of reduction of the resist film after development by the auxiliary light transmitting region 40 is a problem. Does not occur when forming a.

The auxiliary light-shielding region 42 has, for example, a pressure of 1.3.
By scanning a Ga ⁺ focused ion beam with an accelerating voltage of 20 KV and an ion current of 120 pA for 2 minutes in a pyrene gas atmosphere controlled to × 10 ^-4 Pa or less, a thickness of 300 n was obtained.
It can be formed by depositing a layer of m carbon. As the focused ion beam, any ion beam other than the Ga ⁺ ion beam can be used as long as it can form the auxiliary light shielding region. Further, although pyrene gas was used as the carbon-containing gas to form the auxiliary light-shielding region, the gas is not limited to pyrene gas, and any gas containing carbon can be used. Further, a laser beam or an electron beam may be used.

Example 4 Example 4 relates to a halftone phase shift mask according to the second aspect of the present invention. As shown in the schematic partial plan view of FIG.
The halftone phase shift mask of is a transparent substrate 1
Semi-light-shielding layer 14 and a plurality of light transmitting regions 1 formed on
The light transmitting region group composed of 2B and the isolated light transmitting region 30 are provided, and the phase of light passing through the semi-shielding layer 14 and the phase of light passing through the light transmitting regions 12B and 30 are 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 fourth 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 4,
The size of each light transmission region was 0.38 μm × 0.38 μm, and the distance between the centers of each light transmission region was 0.60 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. That is, in the fourth 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, no auxiliary light transmitting region is provided near the light transmitting region 12B.

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.

An auxiliary light transmission region 40 is provided near the isolated light transmission region 30. In the fourth embodiment, the size of the isolated light transmitting region 30 is set to 0.38.
It was set to μm × 0.38 μm. On the other hand, the auxiliary light transmission region 40
The width was 0.2 μm, the length was 0.38 μm, and the center-to-center distance between the isolated light transmitting region 30 and the auxiliary light transmitting region 40 was 0.6 μm. The auxiliary light transmission region 40 is provided in three directions of the isolated light transmission region 30. Example 4
In, the auxiliary light transmitting region is not provided in the direction facing the light transmitting region 12B.

The sectional structures of the isolated light transmitting region 30 and the auxiliary light transmitting region 40 can be substantially the same as the sectional structure shown in FIG.

When a pattern is formed on the resist by using the halftone phase shift mask of the fourth embodiment, as described in the first embodiment, regardless of the arrangement state of the isolated light transmitting regions 30, A resist pattern having substantially the same size as the resist pattern based on the light transmitting region 12B in the light transmitting region group could be obtained.

(Embodiment 5) Embodiment 5 is a modification of Embodiment 4 and relates to a combination of Embodiment 1 and Embodiment 4. In the fifth embodiment, as shown in the plan view of FIG. 8, the light transmission region groups are arranged in a 5 × 5 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 5, the isolated light transmission 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 fourth embodiment. Further, the arrangement and size of the auxiliary light transmitting region 40 were also the same as those in the first and fourth embodiments.

When a pattern is formed on the resist by using the halftone phase shift mask of the fifth embodiment, as described in the first and fourth embodiments, regardless of the arrangement state of the light transmitting regions. A resist pattern having almost the same size could be obtained.

Although the auxiliary light transmitting region 40 is provided in the fourth and fifth embodiments, the auxiliary light shielding region 42 may be provided instead of the auxiliary light transmitting region 40 as in the third embodiment.

The 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. 2A will be described below with reference to FIG. First, the substrate 1 made of a transparent material such as quartz
0 on the surface of the phase shift layer 20 made of, for example, SOG
Is formed by a coating method. The thickness of the phase shift layer 20 was determined so that the difference between the phase of light passing through the light transmitting region 12 and the auxiliary light transmitting region 40 and the phase of light passing through the semi-shielding layer 14 was 180 degrees. Next, on the phase shift layer 20,
The semi-light-shielding layer 14 made of chromium and having a thickness of 22 nm is formed by the sputtering method (see FIG. 9A). When the KrF excimer laser light (wavelength: 248 nm) is used as the exposure light, the light intensity transmittance of the semi-shielding layer 14 having such a thickness is 1
It is 0%. Generally, the light intensity transmittance is, for example, 4 to 20.
The thickness of the semi-light-shielding layer 14 is selected so as to be%. Next, for example, a positive resist 50 is formed on the semi-light-shielding layer 14 by a coating method. Then, for example, by the electron beam drawing method,
The positive resist 50 above the portions where the light transmitting region and the auxiliary light transmitting region are to be formed is irradiated with an electron beam to develop the positive resist 50 (see FIG. 9B). The illustration of the portion where the auxiliary light transmitting region is to be formed is omitted. Then, the semi-light-shielding layer 14 made of chromium is dry-etched in plasma with a mixed gas of chlorine and oxygen (see FIG. 9C), 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 50 is removed. In this way, the halftone type phase shift mask shown in FIG. 2A can be manufactured.

The process for producing the halftone phase shift mask shown in FIG. 2B is basically the same as the method for producing the halftone phase shift mask shown in FIG. The same can be applied except that the order of steps is different. That is, as shown in FIG. 10A, first, a semi-light-shielding layer 14 made of chromium is formed on the surface of a substrate 10 made of a transparent material such as quartz by a sputtering method, and then, on the surface of the substrate 10. Phase shift layer 2 made of SOG, for example
0 is formed by a coating method. Then, for example, a positive resist 50 is formed on the phase shift layer 20 by a coating method.
Then, the positive resist 50 is formed on the portion where the light transmission region and the auxiliary light transmission region are to be formed by, for example, an electron beam drawing method.
The positive resist 50 is developed by irradiating the positive resist 50 with an electron beam (see FIG. 10B). The illustration of the portion where the auxiliary light transmitting region is to be formed is omitted. 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. 10C), 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 50 is removed. Thus, the halftone type phase shift mask shown in FIG. 2B can be manufactured.

A process of manufacturing the substrate digging type halftone phase shift mask shown in FIG. 2C 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, for example, a positive resist 50 is formed on the semi-light-shielding layer 14 by a coating method (see FIG. 11A). Then, for example, by electron beam drawing, the positive resist 50 on the portions where the light transmission region and the auxiliary light transmission region are to be formed is irradiated with an electron beam to develop the positive resist 50 (FIG. 11).
(B)). The illustration of the portion where the auxiliary light transmitting region is to be formed is omitted. After that, the semi-light-shielding layer 14 made of chromium is dry-etched in plasma using a mixed gas of chlorine and oxygen (see FIG. 11C), and the substrate 10 is further subjected to plasma in a mixed gas of carbon tetrafluoride and oxygen. And the positive resist 50 is finally removed. Thus, the halftone type phase shift mask shown in FIG. 2C can be manufactured.

Although the present invention has been described based on the preferred embodiments, 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, the size and arrangement of the auxiliary light transmission region and the auxiliary light shielding region are examples, and by performing various simulations and tests. It can be changed to a desired value or an appropriate value as appropriate. 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. Example 1
3. In Example 3, the auxiliary light transmitting region 40 or the auxiliary light shielding region 42 is provided in the outermost periphery of the light transmitting region group and in the vicinity of the light transmitting region B located at the corner. Thus, it can be provided in the outermost circumference of the light transmitting region group, in the vicinity of the light transmitting region C at a position other than the corner portion.

Various materials used in the manufacturing process of the halftone type 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.

[0068]

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 schematic partial cutaway view of a halftone phase shift mask of Example 1.

FIG. 3 is a diagram showing a result of light intensity simulation of the halftone phase shift masks of Example 1 and Example 2.

FIG. 4 is a diagram showing a result of light intensity simulation of the halftone phase shift mask of Example 3;

FIG. 5 is a schematic plan view of a halftone phase shift mask of Example 3.

FIG. 6 is a schematic partial cutaway view of a halftone phase shift mask of Example 3;

FIG. 7 is a schematic plan view of a halftone phase shift mask of Example 4.

FIG. 8 is a schematic plan view of a halftone phase shift mask of Example 5.

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

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

FIG. 11 is a diagram for explaining a manufacturing process of the halftone phase shift mask shown in FIG. 2C.

FIG. 12 is a schematic partial cutaway view of a conventional halftone phase shift mask.

FIG. 13 is a schematic partial plan view of a conventional halftone phase shift mask.

FIG. 14 is a diagram showing the result of light intensity simulation of a conventional halftone phase shift mask.

FIG. 15 is a schematic partial cutaway view of a typical conventional edge enhancement type phase shift mask.

[Explanation of symbols]

 Reference Signs List 10 substrate 12, 12A, 12B, 12C light transmission region 14 semi-light-shielding layer 20 phase shift layer 30 isolated light transmission region 40 auxiliary light transmission region 42 auxiliary light shielding region

Claims (7)

[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. A halftone phase shift mask, characterized in that auxiliary light transmission areas are provided in the vicinity of the light transmission areas located at the outermost periphery of the light transmission area group. 2. The halftone phase shift mask according to claim 1, wherein an auxiliary light shielding region is provided instead of the auxiliary light transmitting region. 3. A phase of light passing through the semi-shielding layer, which comprises a semi-shielding layer formed on a transparent substrate, a group of light transmitting regions composed of a plurality of light transmitting regions, and an isolated light transmitting region. 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. A halftone phase shift mask, characterized in that an auxiliary light transmission region is provided in the vicinity of the isolated light transmission region. 4. The halftone phase shift mask according to claim 3, wherein auxiliary light transmission regions are provided in the vicinity of the light transmission regions located on the outermost periphery of the light transmission region group. . 5. The auxiliary light shielding region is provided instead of the auxiliary light transmitting region.
Halftone type phase shift mask described in. 6. The halftone type phase shift mask according to claim 2, wherein the auxiliary light shielding region is made of carbon. 7. A halftone system phase shift mask according to claim 1, wherein:
A resist exposure method, which comprises exposing a resist formed on a substrate.