JP2004085612A - Halftone phase shift mask, its manufacturing method and method for forming pattern using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a halftone phase shift mask which can form a pattern with favorable exposure latitude and no pattern abnormality. <P>SOLUTION: The halftone phase shift mask has a mask pattern formed on a translucent substrate 13. The mask pattern comprises a translucent pattern region 11 and a light shielding pattern region 12. The translucent pattern region 11 has one minimum in the distribution of the transmission intensity of light in the shorter side direction. The light shielding pattern 12 has two minima in the distribution of the transmission intensity of light in the shorter side direction when it is assumed that the pattern 12 has the translucency equal to that of the above translucent pattern region 11. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a halftone phase shift mask used for a photolithography method, a manufacturing method thereof, and a pattern forming method using the same.
[0002]
[Prior art]
With the miniaturization of semiconductor elements or semiconductor integrated circuits, a halftone phase shift method has been developed as a method for improving the resolution of photolithography. In the halftone phase shift method, a desired pattern is transferred to a resist film on a semiconductor substrate by exposing through a mask called a halftone phase shift mask. This halftone phase shift mask is to impart transparency to the mask pattern and modulate the phase of the transmitted light with respect to the phase of the transmitted light at the mask opening. Generally, a semi-permeable membrane having a transmittance of 10% or less is used.
[0003]
[Problems to be solved by the invention]
When a fine line pattern is formed by using the halftone phase shift method, it is desirable that the mask pattern has a high transmittance from the viewpoint of improving the exposure margin. However, when patterns of various sizes are mixed, if the transmittance of the mask pattern is high, there is a problem that a pattern abnormality occurs in a large area pattern. Also, in the case of a large-area pattern, there is a problem that, as opposed to the fine line pattern, if the transmittance of the mask pattern is high, the exposure margin decreases.
[0004]
The present invention provides a halftone phase shift mask capable of suppressing the occurrence of pattern abnormality of a large area pattern and a decrease in exposure margin while improving the exposure margin for forming a fine line pattern, a method of manufacturing the same, and a method of using the same. It is an object of the present invention to provide a method for forming a pattern.
[0005]
[Means for Solving the Problems]
To achieve the above object, a halftone phase shift mask of the present invention is a halftone phase shift mask in which a mask pattern is formed on a translucent substrate, wherein the mask pattern is a semi-transmissive pattern part and a light-shielding pattern part. The semi-transmissive pattern portion is a pattern in which one minimal portion exists in the light transmission intensity distribution in the short side direction, and the light-shielding pattern portion has the same translucency as the semi-transmissive pattern portion. When it is assumed that the pattern has two or more minimum parts in the transmission intensity distribution of light in the short side direction.
[0006]
Further, a method of manufacturing a halftone phase shift mask of the present invention is a method of manufacturing a halftone phase shift mask in which a mask pattern is formed on a translucent substrate, wherein a semi-transmissive film is formed on the translucent substrate. Forming the semi-transmissive pattern data and the light-shielding pattern data; and patterning the semi-transmissive film and the light-shielding film based on the semi-transmissive pattern data and the light-shielding pattern data. Forming a pattern, wherein the step of obtaining the light-shielding pattern data includes: forming a semi-transmissive pattern in the mask pattern form; and extracting a portion of the semi-transmissive pattern where light transmission intensity is minimal. Extracting a region surrounded by the minimum portion in the semi-transmissive pattern; and Expanding pattern surrounded by partial region, characterized in that it comprises a step of this enlarged patterned light-shielding pattern.
[0007]
Further, the pattern forming method according to the present invention includes exposing a photoresist film through the halftone phase shift mask according to the present invention, and then developing the photoresist film to transfer a pattern to the photoresist film. It is characterized by.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
In the halftone phase shift mask of the present invention, since a pattern having a relatively small line width is used as the semi-transmissive pattern portion, the effect of improving the resolving power by the halftone phase shift method can be obtained. On the other hand, since a pattern having a relatively large line width is a light-shielding pattern portion, sufficient light-shielding can be realized even in a large-area pattern in which it is difficult to sufficiently shield light with a semi-transmissive film. Can be suppressed from occurring.
[0009]
Further, since the large area pattern is a light shielding pattern portion and is not affected by the transmittance of the semi-transmissive pattern portion, a semi-transmissive film having a high transmittance can be used as the semi-transmissive pattern portion. As a result, the exposure margin of the fine pattern can be improved. In the case of a large-area pattern, the exposure margin may be deteriorated by using the halftone phase shift method. However, since this is used as a light-shielding pattern portion, a good exposure margin can be obtained. That is, good exposure latitude can be obtained in both the fine pattern and the large area pattern.
[0010]
Next, an example of a halftone phase shift mask according to the present invention will be described with reference to the drawings.
[0011]
FIG. 1 is a schematic diagram showing a halftone phase shift mask according to the first embodiment of the present invention. As shown in this figure, in this halftone phase shift mask, a mask pattern is formed on a translucent substrate 13, and this mask pattern is composed of a semi-transmissive pattern section 11 and a light-shielding pattern section 12. I have. The semi-transmissive pattern portion 11 is disposed in a pattern portion having a relatively small line width in the mask pattern, and the light-shielding pattern portion 12 is disposed in a pattern portion having a relatively large line width in the mask pattern. . The arrangement of the translucent pattern portion 11 and the light-shielding pattern portion 12 will be described later.
[0012]
The semi-transmissive pattern section 11 is formed of a light-transmitting phase shift film. The transmittance of the semi-transmissive pattern portion 11 is not particularly limited, but is, for example, 10 to 80%, and preferably 20 to 50%. As a material for forming the semi-transmissive pattern portion 11, for example, molybdenum silicide or the like can be used. Further, as a material for forming the light-shielding pattern portion 12, for example, chrome or the like can be used. As the translucent substrate 13, for example, a glass substrate, a quartz substrate, or the like can be used.
[0013]
Next, the arrangement of the translucent pattern portion and the light shielding pattern portion will be described in detail.
[0014]
FIG. 2A is a schematic diagram illustrating an example of a mask pattern of a halftone phase shift mask. The mask pattern includes a plurality of patterns 14, 15, and 16 having different line widths. The line width of each pattern is not particularly limited, but may be, for example, in the range of 0.1 to 2 μm.
[0015]
FIGS. 2B and 2C are schematic diagrams each showing an example of the intensity distribution of light transmitted through the mask pattern when all the mask patterns have the same transmittance as the semi-transmissive pattern portion. This shows the intensity distribution of transmitted light in the short side direction (line width direction) of the pattern. As shown in FIG. 2B, in the pattern 14 having a relatively small line width, one minimum point exists in the intensity distribution curve of the transmitted light in the short side direction (line width direction). That is, in this pattern, sufficient light shielding is achieved. On the other hand, as shown in FIG. 2C, in the patterns 15 and 16 having a relatively large line width, two minimum portions exist in the intensity distribution curve of the transmitted light in the short side direction (line width direction). The intensity of the transmitted light is high in the portion between the minimum portions, that is, sufficient light shielding is not achieved. When the pattern is transferred to the resist film in such a state, it is expected that a pattern abnormality will occur, such as the dissolution of the resist at the center of the pattern.
[0016]
FIG. 3 shows the relationship between the line width of the pattern and the slope of the transmitted light intensity. In the figure, reference numeral 22 denotes a case where the mask pattern is formed of a semi-transmissive film, and reference numeral 21 denotes a case where the mask pattern is formed of a light-shielding film. Note that, in this drawing, as an example, a case where the transmittance of the semi-transmissive film is 50% and ArF excimer laser light of 2/3 annular illumination is used is shown. Here, the inclination of the transmitted light intensity is the inclination of the tangent line at the boundary between the target remaining resist and the resist dissolution part in the light intensity curve in which the X axis is the position in the line width direction on the wafer. The larger this is, the better the exposure margin is. As shown in this figure, a semi-transmissive film is more advantageous for a pattern with a relatively small line width, and a light-shielding film is more advantageous for a pattern with a relatively large line width.
[0017]
In the halftone phase shift mask according to the present embodiment, as shown in FIG. 2B, a pattern (a pattern having a relatively small line width) in which one minimum point exists in the intensity distribution curve of the transmitted light in the short side direction is cut in half. As shown in FIG. 2C, a pattern having two minimum points in the intensity distribution curve of the transmitted light in the short side direction (a pattern having a relatively large line width) is arranged as a light-shielding pattern part. .
[0018]
That is, in this halftone phase shift mask, a pattern with a small line width that can sufficiently shield light with a semi-transmissive film is a semi-transmissive pattern portion, and a pattern with a large line width that cannot fully shield light with a semi-transmissive film is This is a light-shielding pattern portion. Therefore, in a pattern having a small line width, an effect of improving the resolving power by the halftone phase shift method can be realized. On the other hand, in the case of a pattern having a large line width, the occurrence of pattern abnormality accompanying the halftone phase shift method can be suppressed by using the light-shielding pattern portion.
[0019]
Further, as described above, with respect to the exposure margin, a semi-transmissive film is advantageous in a pattern with a small line width, and a light-shielding film is advantageous in a pattern with a large line width. Therefore, as in the above-described halftone phase shift mask, a pattern having a small line width is used as a semi-transmissive pattern portion, and a pattern having a large line width is used as a light-shielding pattern portion. A margin can be achieved.
[0020]
As described above, in the halftone phase shift mask, of the mask patterns, the pattern to be the semi-transmissive pattern portion and the pattern to be the light-shielding pattern portion are determined by the line width. As described above, this line width is set according to the intensity distribution of transmitted light in the line width (short side) direction of the pattern when all the mask patterns have the same transmittance as the semi-transmissive pattern portion. Is done.
[0021]
Therefore, the preferable range of the line width of the semi-transmissive pattern portion and the light-shielding pattern portion differs depending on the transmittance of the semi-transmissive pattern portion. Normally, the higher the transmittance, the smaller the line width of the semi-transmissive pattern portion and the larger the line width of the light-shielding pattern portion. For example, when the transmittance is 50%, the line width of the semi-transmissive pattern portion is preferably less than 0.2 μm, and more preferably less than 0.15 μm. Note that the lower limit of the line width of the semi-transmissive pattern portion is a value exceeding 0. The line width of the light-shielding pattern portion is preferably 0.2 μm or more, and more preferably 0.15 μm or more. The upper limit of the line width of the light-shielding pattern portion is controlled by design pattern data, and is not particularly limited, but is, for example, 1000 μm or less.
[0022]
Further, it is preferable that the intensity distribution of the transmitted light is evaluated for light used when performing exposure using a halftone phase shift mask. In other words, the line width of the pattern in which two minimum points exist in the intensity distribution curve of the transmitted light (that is, the pattern serving as the semi-transmission pattern portion), and one minimum point exists in the intensity distribution curve of the transmitted light. It is preferable that the line width of the pattern (that is, the pattern to be the light-shielding pattern portion) is set according to the type of light used for exposure. For example, when the light used for exposure is an ArF excimer laser, the line width of the semi-transmissive pattern portion is preferably less than 0.2 μm, and more preferably less than 0.15 μm. Note that the lower limit of the line width of the semi-transmissive pattern portion is a value exceeding 0. The line width of the light-shielding pattern portion is preferably 0.2 μm or more, and more preferably 0.15 μm or more. The upper limit of the line width of the light-shielding pattern portion is controlled by design pattern data, and is not particularly limited, but is, for example, 1000 μm or less.
[0023]
Next, an example of a method for manufacturing the halftone phase shift mask will be described. In this halftone phase shift mask, a semi-transmissive film and a light-shielding film are formed on a light-transmitting substrate, and the semi-transmissive film and the light-shielding film are formed on the basis of previously prepared semi-transmissive pattern data and light-shielding pattern data. It can be manufactured by patterning.
[0024]
The method for forming the semi-transmissive film and the light-shielding film is not particularly limited. For example, the semi-transmissive film can be formed by molybdenum silicide sputtering or the like, and the light-shielding film can be formed by vacuum evaporation or sputtering of chromium. The film can be formed by the above method. Also, the patterning method is not particularly limited, and the patterning method can be implemented by photo or electron beam lithography and etching.
[0025]
The semi-transmissive pattern data and the light-shielding pattern data can be created, for example, as follows.
[0026]
First, a semi-transmissive film is formed on a transparent substrate such as a glass substrate, and is patterned to form a semi-transmissive pattern 31 in a desired mask pattern (FIG. 4A). Subsequently, by irradiating the semi-transmission pattern 31 with light and measuring the transmission intensity of the light, the transmission intensity distribution of light in the semi-transmission pattern 31 is obtained. At this time, the light irradiation conditions are not particularly limited, but are preferably the same as the exposure conditions when the manufactured halftone phase shift mask is used.
[0027]
From the obtained transmission intensity distribution, a portion (hereinafter, referred to as a “light intensity minimum portion”) 32 where the light transmission intensity is minimum in the semi-transmission pattern 31 is extracted (FIG. 4B), and then the semi-transmission pattern 31. Then, an area 33 surrounded by the light intensity minimum part 32 is extracted (FIG. 4C). Then, the pattern of the region 33 is enlarged to be a light shielding pattern 34 (FIG. 4D). At this time, the entire pattern is enlarged so that the edge of the enlarged pattern is 0.01 to 0.2 μm outside the edge of the pattern before enlargement, and further 0.05 to 0.15 μm outside. It is preferred to enlarge. It is preferable that the amount of enlargement is set according to the transmittance of the semi-transmissive pattern and the type of light. For example, when the transmissivity of the semi-transmissive pattern is 20% and an ArF excimer laser for quadrupole illumination is used, the amount of enlargement is preferably 0.1 μm.
[0028]
Note that, in the above data creation method, it is preferable to obtain the light intensity distribution by computer simulation instead of actually fabricating the mask as described above. Operations such as pattern extraction and enlargement are preferably performed using a computer.
[0029]
Next, an example of a pattern forming method using the halftone phase shift mask will be described. First, a photoresist is applied on a semiconductor substrate, and the photoresist is exposed using the halftone phase shift mask. As the light used for the exposure, for example, ultraviolet light having a wavelength of 450 nm or less, in particular, G-ray (wavelength 436 nm), i-ray (wavelength 365 nm), KrF excimer laser (wavelength 248 nm), ArF excimer laser (wavelength 193 nm), F ₂ Laser (wavelength: 156 nm) and the like can be mentioned. After the exposure, the pattern is transferred to the photoresist by developing the photoresist.
[0030]
Note that the obtained pattern is used as, for example, an etching mask for etching a film to be processed (for example, a semiconductor film, an insulating film, a metal film, or the like) formed on a semiconductor substrate, or for implanting impurity ions into a semiconductor substrate. Can be used as an ion implantation mask or the like.
[0031]
【The invention's effect】
As described above, according to the halftone phase shift mask of the present invention, it is possible to suppress the occurrence of pattern abnormalities and the decrease in exposure margin of a large area pattern while improving the exposure margin for forming a fine line pattern. .
[Brief description of the drawings]
FIG. 1 is a plan view showing an example of a halftone phase shift mask according to the present invention.
FIG. 2 is a diagram showing a mask pattern of the halftone phase shift mask (FIG. 2A) and a transmitted light intensity distribution (FIGS. 2B and C) in each pattern portion when the mask pattern is entirely formed of a semi-transmissive film. is there.
FIG. 3 is a diagram illustrating a relationship between a line width of a pattern and a gradient of transmitted light intensity.
FIG. 4 is a plan view for explaining an example of a method of creating semi-transmissive pattern data and light-shielding pattern data in manufacturing the halftone phase shift mask.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Semi-transmissive pattern part 12 Light-shielding pattern part 13 Translucent substrate 14 Pattern data of small line width pattern 15 Pattern data of medium line width pattern 16 Pattern data of large line width pattern 31 Semi-transmissive pattern 32 formed in a mask pattern shape Light intensity minimum part 33 Part surrounded by light intensity minimum part 34 Light shielding pattern

Claims (6)

A halftone phase shift mask in which a mask pattern is formed on a light-transmitting substrate, wherein the mask pattern includes a semi-transmissive pattern portion and a light-shielding pattern portion,
The semi-transmissive pattern portion is a pattern in which there is one minimal portion in the light transmission intensity distribution in the short side direction,
Assuming that the light-shielding pattern portion has the same light-transmitting property as the semi-transmissive pattern portion, the light-shielding pattern portion is a pattern in which two or more portions are minimal in the light transmission intensity distribution in the short side direction. A halftone phase shift mask. 2. A semi-transmissive pattern part used in exposure using an ArF excimer laser, wherein a dimension in a short side direction is less than 0.2 μm, and a dimension in a short side direction of the light shielding pattern part is 0.2 μm or more. 2. The halftone phase shift mask according to 1. The halftone phase shift mask according to claim 1, wherein a light transmittance of the semi-transmissive pattern portion is 10 to 80%. A method for manufacturing a halftone phase shift mask in which a mask pattern is formed on a light-transmitting substrate,
Forming a semi-transmissive film and a light-shielding film on the light-transmitting substrate; obtaining semi-transmissive pattern data and light-shielding pattern data; Patterning based on pattern data, the step of forming the mask pattern,
The step of obtaining the light-shielding pattern data includes: forming a semi-transmissive pattern in the mask pattern shape; extracting a portion where the light transmission intensity is minimal in the semi-transmissive pattern; A step of extracting a region surrounded by a part to be formed, and a step of enlarging a pattern of the area surrounded by the minimum part, and using the expanded pattern as a light-shielding pattern. A method for manufacturing a tone phase shift mask. The pattern in a region surrounded by the minimum portion is enlarged such that an edge of the enlarged pattern is 0.01 to 0.2 μm outside an edge of the pattern before enlargement. Item 5. A method for manufacturing a halftone phase shift mask according to Item 4. 4. A pattern forming method comprising: exposing a resist film through the halftone phase shift mask according to claim 1; and developing the resist film to transfer a pattern to the resist film. Method.

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