JP2005275138A - Phase shift mask and pattern exposing method using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a phase shift mask which improves the NILS value of a pattern of ≤50 nm in mask pattern size when the pattern is exposed and a pattern exposing method using the same. <P>SOLUTION: This phase shift mask is provided with a translucent film having a phase difference 2nπ (n=0, 1, 2, 3, ...) at a part adjacent to a phase shift part, and transmissivity to light transmitted through the adjacent region is made low to cut leak light from the region. Consequently, decrease of NILS value in the fine pattern of ≤50 nm in mask size is prevented. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a phase shift mask and a pattern exposure method using the same, and more particularly to a phase shift mask that enables high resolution exposure of a fine pattern in a chromeless type phase shift mask and a pattern exposure method used therefor.

  In recent years, with the miniaturization of patterns accompanying the increase in the density of semiconductor integrated circuits, the exposure wavelength has been shortened. At present, the mainstream is a krypton fluoride (KrF) excimer laser with a wavelength of 248 nm. Subsequently, an argon fluoride (ArF) excimer laser with a wavelength of 193 nm and an F2 laser with a wavelength of 157 nm are listed as candidates. Further, as a technique that exceeds the resolution limit determined from the wavelength of light, there is a phase shift mask that obtains high resolution using the phase difference of light.

ここで、ＮＩＬＳはマスクパターンの光学像の対数勾配（δＩｎ Ｉ／δＸ）と対象パターン幅（Ｗ）との積で表され、一般的に収差やフレアなどの要因を除いて２程度あれば、露光やフォーカスマージンのあるプロセスとして定義できる。 A typical example of the phase shift mask is a Resonson type phase shift mask. FIG. 13 is a chart showing an aerial image of exposure light with a wavelength of 157 nm, NA 0.85, σ 0.30, pattern size 65 nm, and Resonson type phase shift mask.
As the mass pattern, a periodic 65 nm line and space (L / S (1: 1)) pattern is used. Since the light intensity corresponds to the pattern shape formed on the resist, for example, when W shown in the figure is a pattern width, it can be seen that a line and a pitch of about 65 nm are formed. In order to perform exposure processing on a positive type or negative type resist and obtain a pattern shown in the drawing, the contrast of light is important. It is desirable that the light intensity has a large light / dark difference and the change is steep. There is NILS (Normalized Image Log-Slope) as a value for evaluating the optical contrast of this pattern. NILS is expressed by the following equation.

Here, NILS is represented by the product of the logarithmic gradient (δIn I / δX) of the optical image of the mask pattern and the target pattern width (W). Generally, if there are about 2 except for factors such as aberration and flare, It can be defined as a process with exposure and focus margin.

  However, in the case of the Levenson type phase shift mask, double exposure is required and the alignment accuracy becomes strict, so that a chromeless type phase shift mask that does not require double exposure has been attracting attention.

FIG. 14 is a cross-sectional view showing a cross-sectional structure of a chromeless type phase shift mask and a halftone type phase shift mask equivalent thereto.
As shown in FIG. 14, the chromeless phase shift mask 1401 is equivalent to a halftone phase shift mask 1402 having a transmittance of 100% with a transmission part 1403 having a 180 ° phase difference.

FIG. 15 is a chart showing the relationship between the transmittance of the transmission part 1403 having a 180 ° phase difference of the halftone phase shift mask shown in FIG. 14 and the NILS value. The mask pattern is an isolated pattern that is not close to the surrounding pattern, and a line-and-space pattern with a line width of 35 nm and a pitch of 1: 2.2 to 1: 3, and illumination is shown in FIG. Illumination 1600 (wavelength 157 nm, NA 0.85, 0.80 / 0.53) was used.
From FIG. 15, it can be seen that the NILS value increases as the transmittance of the transmission part 1403 having the 180 ° phase difference shown in FIG. 14 increases.

FIG. 17 is a chart showing an aerial image of exposure light when a chromeless type phase shift mask is used. The mask pattern is an isolated pattern, and annular illumination shown in FIG. 16 was used. The light intensity is plotted on the vertical axis and the position is plotted on the horizontal axis, and the logarithmic gradient (δIn I / δX) and the target pattern width (W) for determining the NILS described above are shown in the chart.
The phase shift mask reverses the phase of the light transmission portion of the mask by 180 °, thereby canceling out the 0th-order analysis light and causing two ± 1st-order diffracted lights to interfere with each other to form an image. By using such a technique, high resolution of the pattern is realized.

FIG. 18 shows the result of an optical simulation when an isolated pattern is exposed with a chromeless phase shift mask using the annular illumination (wavelength 157 nm, NA 0.85, 0.80 / 0.53) shown in FIG. It is a chart showing.
The horizontal axis represents the mask dimension, and the vertical axis represents the optical image at each slice level. The light intensity is plotted in a stepwise manner from 0.1 to 0.9. For example, when the mask dimension is 35 nm, the value plotted on the vertical axis is considered to correspond to W shown in FIG.

  In this case, as shown in FIG. 18, the point where the light intensity (threshold) is 0.2 is almost an appropriate dimension within a mask dimension of 35 to 50 nm. When the mask size is 50 nm or more, the mask size becomes flat and the linearity of the pattern is lost. However, various countermeasures in this range have been studied, and therefore will not be discussed in the present invention.

FIG. 19 shows each mask size when an isolated pattern is exposed with a chromeless phase shift mask using the annular illumination (wavelength 157 nm, NA 0.85, 0.80 / 0.53) shown in FIG. It is a chart showing a change of a NILS value.
It can be seen that the NILS value deteriorates rapidly when the mask dimension is 50 nm or less.

FIG. 20 shows each mask size when an isolated pattern is exposed with a chromeless phase shift mask using the annular illumination (wavelength 157 nm, NA 0.85, 0.80 / 0.53) shown in FIG. It is a chart showing an optical image.
It can be seen that when the mask dimension is 50 nm or less, the bottom of the optical image (the portion where the light intensity is the weakest) is gradually shifted upward. This indicates that the “dark” portion of the optical image is not sufficiently dark. That is, the light contrast is insufficient, and as a result, as shown in FIG. 19, the NILS value deteriorates.

  As described above, when the mask size is reduced, the light intensity of the phase shift portion is increased, and a phenomenon that a sufficient NILS value cannot be obtained occurs. This is presumably because the amount of leaked light that enters the phase shift unit from the region adjacent to the phase shift unit increases, and the light intensity of the phase shift unit that should originally function as a light blocking unit increases.

  As described above, in the exposure process using the chromeless type phase shift mask, when the pattern size is reduced, the NILS value is rapidly deteriorated although there is optical linearity. This deteriorates the dimensional controllability of the pattern.

  The present invention has been made on the basis of recognition of such a problem, and an object of the present invention is to provide a phase shift mask for improving the NILS value when a pattern having a mask pattern size of 50 nm or less is exposed, and a pattern using the same. It is to provide an exposure method.

  The phase shift mask of the present invention is provided with a translucent film having a phase difference of 2nπ (n = 0, 1, 2, 3...) In a portion adjacent to the phase shift portion, and the light transmitted through the adjacent region. Leakage light from this region is cut by reducing the transmittance. The NILS value is prevented from deteriorating in a fine pattern having a mask dimension of 50 nm or less.

According to the present invention, there is provided a chromeless type phase shift mask which gives a phase difference to transmitted exposure light and improves resolution by utilizing mutual interference of transmitted exposure light,
A transparent substrate;
A phase shift part formed on the transparent substrate;
A transmittance adjusting unit that is formed adjacent to the phase shift unit and lowers the transmittance of the exposure light; and
The transmittance adjusting unit is provided with a phase shift mask having a phase difference of 2nπ (n = 0, 1, 2, 3,...) With exposure light.

  The transmittance adjusting unit is formed of a transmittance adjusting film that adjusts the transmittance of incident light, and a phase shifter film that shifts the phase by 2nπ (n = 0, 1, 2, 3,...). A phase shift mask is provided.

  The phase shift portion may be provided with a phase shift mask having a trench shape dug into the transparent substrate with a phase difference of 180 ° with respect to the exposure light.

  The phase shift unit is supplied with a phase shift mask formed by depositing a phase shifter film having a phase difference of 180 ° with respect to the exposure light on the transparent substrate.

  In addition, a phase shift mask that is the same material as the phase shifter film that forms the phase shift unit and the phase shifter film that forms the transmittance adjusting film is provided.

  A phase shift mask using tantalum silicide (TaSi) as a material for the transmittance adjusting film is provided.

  Further, a phase shift mask using zircon silicide (ZrSi) as a material for the transmittance adjusting film is provided.

  In addition, a phase shift mask using molybdenum silicide (MoSi) as a material of the transmittance adjusting film is provided.

  Further, a phase shift mask using chromium fluoride (CrF) as a material of the phase shifter film is provided.

In addition, a phase shift mask using silicon oxide (SiO ₂ ) as a material of the phase shifter film is provided.

  Further, a phase shift mask using silicon oxynitride (SiON) as a material of the phase shifter film is provided.

Furthermore, it is a pattern exposure method by an exposure process using a phase shift mask,
The phase mask has a transmittance adjusting unit having a phase difference of 2nπ (n = 0, 1, 2, 3...) Between the phase shift unit corresponding to the fine pattern and the exposure light adjacent thereto on the transparent substrate. Formed,
There is provided a pattern exposure method using a phase shift mask, wherein the optical contrast value of a pattern formed on a resist is increased by selecting an optimal size of the transmittance adjusting unit for the size of the phase shift unit.

  According to the present invention, in a fine pattern having a mask dimension of 50 nm or less, it is possible to sufficiently maintain the contrast in the phase shift portion by cutting the leaked light from the adjacent region to the phase shift portion. In this way, by maintaining a high NILS value, the pattern dimension controllability can be improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Chromeless type phase shift masks include a trench type that digs a phase shift portion on a transparent substrate and a mesa type that deposits a shifter film.
First, as a chromeless type phase shift mask according to the first embodiment of the present invention, a trench type (1) chromeless type phase shift mask will be described. FIG. 1 is a schematic diagram showing a cross-sectional structure of a trench type (1) chromeless type phase shift mask.
Conventionally, a trench type chromeless type phase shift mask has a structure in which a groove is dug so that a phase difference of 180 ° is generated as a phase shift portion in a transparent substrate. On the other hand, the chromeless type phase shift mask of FIG. 1 is adjacent to both sides of the phase shift portion 102 dug so that a phase difference of 180 ° is generated on the transparent substrate 101, and the transmittance adjustment film 103 and A phase shifter film 104 having a phase 2nπ (n = 0, 1, 2, 3,...) Is provided.

FIG. 2 is a schematic diagram showing a mask manufacturing process of the chromeless type phase shift mask shown in FIG.
First, tantalum (Ta) to be the transmittance adjusting film 202 is formed on the transparent substrate 201, and chromium fluoride (CrF) to be the phase shifter film 203 is formed thereon (FIG. 2A).
Next, first patterning is performed on the electron beam resist 204 to form the phase shift portion 102 shown in FIG. 1 (FIG. 2B).
After patterning the electron beam resist 204, the phase shifter film 203 and the transmittance adjusting film 202 are etched, and at the same time, digging is performed for the 180 ° phase (FIG. 2C).
Next, after removing the electron beam resist 204, the electron beam resist 205 is subjected to second patterning in order to form a transmittance adjusting film 202 and a phase shifter film 203 having a predetermined line width on both sides of the digging. (FIG. 2 (d)).
After the patterning of the electron beam resist 205, the transmittance adjusting film 202 and the phase shifter film 203 other than the region adjacent to the phase shift portion 102 shown in FIG. 1 are etched (FIG. 2E).
Finally, the electron beam resist 205 is removed to complete (FIG. 2F).

  FIG. 3 shows the relationship between the dimension of the phase shift portion S and the NILS value, with the semi-transparent film portion C as the film that combines the transmittance adjusting film 103 and the phase shifter film 104 of the chromeless type phase shift mask shown in FIG. It is a chart. The translucent film part C was set to 20 to 60 nm in increments of 10 nm. The optical system is an annular illumination with NA of 0.58 and 0.80 / 0.53, and the transmissivity of the translucent film part is 6%.

From FIG. 3, when the size of the translucent film part C is 20 nm, the NILS value reaches a peak at 3.5 when the size of the phase shift part S is 44 nm. Further, when the size of the translucent film part C is changed to 40, 50, 60, the NILS value peaks when the size of the phase shift part S is 50 nm or less, and the value can be secured to 3 or more. I understand.
Thus, by optimizing the sizes of the translucent film part C and the phase shift part S, it can be seen that the NILS value does not deteriorate even if the size of the phase shift part S is 50 nm or less.

FIG. 4 is a chart in which the optimum dimension of the phase shift portion S is plotted with respect to the size of the translucent film portion C of FIG. As the material of the translucent film part C, chromium (Cr) and tantalum (Ta) were used, and the transmittance was changed stepwise from 3 to 20%.
From FIG. 4, it can be seen that the slope of the graph becomes gentler as the transmittance of the translucent film portion C increases. By setting the transmissivity of the semitransparent film part C high, the ratio of the change in the optimum value of the phase shift part S with respect to the dimension of the semitransparent film part C becomes small. This means that dimensional controllability of the target phase shift mask can be easily obtained.

FIG. 5 is a chart in which the dimensions of the optical image using the phase shift portion S optimized from FIG. 4 are plotted against the size of the semitransparent film portion C. The transmittance of the translucent film part C was changed stepwise from 0 to 20%.
FIG. 5 shows that the slope of the curve becomes gentler as the transmittance of the translucent film portion C increases. This means that by setting the transmissivity of the semitransparent film part C to be high, even if the dimensions of the semitransparent film part C vary, the target optical dimensions can be easily obtained. Therefore, if the transmissivity of the translucent film portion C is adjusted to be higher, the pattern dimension controllability is improved. Further, as is clear from FIG. 5, the NILS value can be prevented from decreasing in the optical image range of 35 to 60 nm by changing the size of the translucent portion C.

FIG. 6 shows an exposure process of an isolated pattern using the chromeless phase shift mask according to the embodiment of the present invention using the annular illumination (wavelength 157 nm, NA 0.85, 0.80 / 0.53) shown in FIG. It is the graph showing the optical image in each mask dimension at the time of doing. The transmissivity of the translucent film part at this time is set to 6%. The mask dimensions are changed to 20, 40 and 60 nm to represent the respective optical images.
From FIG. 6, even if the mask dimension is 50 nm or less, the NILS value is not deteriorated. The effect is obvious at a glance by comparing with FIG.

Next, as a chromeless type phase shift mask according to the second embodiment of the present invention, a mesa type (1) chromeless type phase shift mask will be described. FIG. 7 is a schematic view showing a cross-sectional structure of a mesa type (1) chromeless type phase shift mask.
Conventionally, mesa-type chromeless phase shift masks have a structure in which phase shift portions are deposited by a shifter film so that a phase difference of 180 ° is generated. On the other hand, the chromeless phase shift mask of FIG. 7 is adjacent to both sides of the phase shift portion 702 deposited on the transparent substrate 701 so as to produce a phase difference of 180 °, and the phase of the transmittance adjustment film 703. A phase shifter film 704 having 2nπ (n = 0, 1, 2, 3,...) Is provided.

FIG. 8 is a schematic view showing a mask manufacturing process of the chromeless type phase shift mask shown in FIG.
First, tantalum (Ta) to be the transmittance adjusting film 802 is formed on the transparent substrate 801 (FIG. 8A).
Next, in order to form the phase shift part 702 shown in FIG. 7, the first patterning is performed on the electron beam resist 803 (FIG. 8B).
After the patterning of the electron beam resist 803, the transmittance adjusting film 802 is etched (FIG. 8C).

Next, after removing the electron beam resist 803, chromium fluoride (CrF) to be the phase shifter film 804 is formed (FIG. 8D).
Next, in order to form a transmittance adjusting film 802 and a phase shifter film 804 having a predetermined line width on both sides of the phase shift portion 702 shown in FIG. 7, the second patterning is performed on the electron beam resist 805 (FIG. 8). (E)).
After patterning the electron beam resist 805, the phase shifter film 804 and the transmittance adjustment film 802 are etched (FIG. 8F).
Next, after removing the electron beam resist 805 (FIG. 8G), third patterning is performed on the electron beam resist 806 in order to set the phase of the phase shift unit 702 shown in FIG. FIG. 8 (h)).
After patterning the electron beam resist 806, etching is performed until the phase of the phase shift portion 702 shown in FIG. Finally, the electron beam resist 806 is removed to complete (FIG. 8 (i)).

Even when the mesa type (1) chromeless phase shift mask according to the second embodiment of the present invention is used, the optical characteristics thereof are the trench type (1) chromeless type described in the first embodiment. This is the same as the phase shift mask.
In the case of this embodiment, the phase shifter film forming the phase shift portion and the phase shifter film formed on the transmittance adjusting film can be formed in the same process.

Next, a trench type (2) chromeless type phase shift mask will be described as a chromeless type phase shift mask according to a third embodiment of the present invention. FIG. 9 is a schematic diagram showing a cross-sectional structure of a trench type (2) chromeless type phase shift mask.
The trench-type (2) chromeless type phase shift mask includes a transmittance adjustment film 903 adjacent to both sides of the phase shift portion 902 dug so as to produce a phase difference of 180 ° on the transparent substrate 901. The shape without the trench-type (1) phase shifter film shown in FIG. Here, the film used as the transmittance adjusting film 903 is a material that can adjust the transmittance and have a phase difference of 2nπ (n = 0, 1, 2, 3,...) With incident light. Is adopted.

FIG. 10 is a schematic diagram showing a mask manufacturing process of the chromeless type phase shift mask shown in FIG.
First, tantalum silicide (TaSi) to be the transmittance adjusting film 1002 is formed on the transparent substrate 1001 (FIG. 10A).
Next, in order to form the phase shift part 902 shown in FIG. 9, the first patterning is performed on the electron beam resist 1003 (FIG. 10B).
After the patterning of the electron beam resist 1003, the transmittance adjusting film 1002 is etched, and at the same time, digging is performed for 180 ° phase (FIG. 10C).
Next, after removing the electron beam resist 1003 (FIG. 10D), the second patterning is performed on the electron beam resist 1004 in order to form a transmittance adjusting film 1002 having a predetermined line width on both sides of the digging. (FIG. 10 (e)).
After patterning the electron beam resist 1004, the transmittance adjusting film 1002 other than the region adjacent to the phase shift portion 902 shown in FIG. 9 is etched (FIG. 10F).
Finally, the electron beam resist 1004 is removed to complete (FIG. 10G).

Even when the trench type (2) chromeless phase shift mask according to the fourth embodiment of the present invention is used, the optical characteristics thereof are the trench type (1) chromeless type described in the first embodiment. This is the same as the phase shift mask.
Further, in the case of the present embodiment, since the transmittance adjusting film also has a role of a phase shifter film, the same film is obtained, so that the manufacturing process can be simplified.

Next, a mesa type (2) chromeless type phase shift mask will be described as a chromeless type phase shift mask according to a fourth embodiment of the present invention. FIG. 11 is a schematic view showing a cross-sectional structure of a trench type (2) chromeless type phase shift mask.
The mesa type (2) chromeless type phase shift mask includes a transmittance adjusting film 1103 adjacent to both sides of the phase shift portion 1102 deposited on the transparent substrate 1101 so as to produce a phase difference of 180 °. The mesa mold (1) shown in FIG. 7 has a shape without a phase shifter film on the transmittance adjusting film. Here, the film used as the transmittance adjusting film 1103 is a material that can adjust the transmittance and have a phase difference with incident light of 2nπ (n = 0, 1, 2, 3,...). Is adopted.

FIG. 12 is a schematic view showing a mask manufacturing process of the chromeless type phase shift mask shown in FIG.
First, tantalum silicide (TaSi) to be the transmittance adjusting film 1202 is formed on the transparent substrate 1201 (FIG. 12A).
Next, first patterning is performed on the electron beam resist 1203 in order to form the phase shift portion 1102 shown in FIG. 11 (FIG. 12B).
After patterning the electron beam resist 1203, the transmittance adjusting film 1202 is etched (FIG. 12C).

Next, after removing the electron beam resist 1203, chromium fluoride (CrF) to be the phase shifter film 1204 is formed to have a phase of 180 ° (FIG. 13D).
Next, in order to form the phase shift part 1102 shown in FIG. 11, the second patterning is performed on the electron beam resist 1205 (FIG. 12E).
After patterning the electron beam resist 1205, the phase shifter film 1204 is etched (FIG. 12F). Finally, the electron beam resist 1205 is removed to complete (FIG. 12G).

Even when the mesa type (2) chromeless type phase shift mask according to the fourth embodiment of the present invention is used, the optical characteristics thereof are the trench type (1) chromeless type described in the first embodiment. This is the same as the phase shift mask.
Further, in the case of the present embodiment, since the transmittance adjusting film also has a role of a phase shifter film, the same film is obtained, so that the manufacturing process can be simplified.
In the chromeless phase shift masks according to the first and second embodiments described so far, tantalum (Ta) has been described as an example of the transmittance adjusting film. However, tantalum silicide (TaSi), zircon silicide ( ZrSi) and molybdenum silicide (MoSi) can be used, and the phase shifter film can be used in combination with silicon oxide (SiO ₂ ) or silicon oxynitride (SiON) in addition to chromium fluoride (CrF).

  In the chromeless type phase shift mask according to the second and fourth embodiments, a chromium fluoride (as a transmittance adjusting film having a phase difference of 2nπ (n = 0, 1, 2, 3...)) Although description has been made taking CrF) as an example, silicon oxide (SiO 2) or silicon oxynitride (SiON) can be used.

As described above, the use of the chromeless type phase shift mask of the present invention provides an exposure method that allows easy dimension control without deteriorating the NILS value even in a fine pattern having a mask size of 50 nm or less. can do.
This greatly contributes to semiconductor microfabrication technology.

It is a schematic diagram showing the cross section structure of the trench type | mold (1) chromiumless type | mold phase shift mask concerning embodiment of this invention. It is a schematic diagram showing the mask manufacturing process of the chromeless type phase shift mask shown in FIG. It is a chart showing the relationship between the dimension of the translucent film | membrane part C and the phase shift part S, and the NILS value of the chromiumless type | mold phase shift mask of this invention. 5 is a chart in which optimum dimensions of a phase shift portion S are plotted with respect to the size of a semitransparent film portion C. 5 is a chart in which the dimensions of an optical image using the phase shift portion S optimized from FIG. 4 are plotted against the size of the semitransparent film portion C. FIG. It is the graph showing the optical image in each mask dimension at the time of exposing an isolated pattern with the chromeless type | mold phase shift mask concerning embodiment of this invention. It is a schematic diagram showing the mesa type (1) chromeless type phase shift mask sectional structure concerning an embodiment of the invention. It is a schematic diagram showing the mask manufacturing process of the chromeless type phase shift mask shown in FIG. It is a schematic diagram showing the cross section structure of the trench type | mold (2) chromeless type | mold phase shift mask concerning embodiment of this invention. FIG. 10 is a schematic diagram illustrating a mask manufacturing process of the chromeless phase shift mask illustrated in FIG. 9. It is a schematic diagram showing a mesa type (2) chromeless type phase shift mask cross-sectional structure according to an embodiment of the present invention. It is a schematic diagram showing the mask manufacturing process of the chromeless type phase shift mask shown in FIG. It is the chart showing the aerial image of the exposure light of a levelson type phase shift mask. It is sectional drawing showing the cross-section of a chromeless type | mold phase shift mask and a halftone type | mold phase shift mask equivalent to this. FIG. 15 is a chart showing the relationship between the transmittance of a transmission part having a 180 ° phase difference and the NILS value of the halftone phase shift mask shown in FIG. 14. It is a schematic diagram showing the shape of annular illumination. It is the chart showing the aerial image of exposure light at the time of using a chromeless type phase shift mask. It is a chart showing the result of an optical simulation when an isolated pattern is exposed with a chromeless phase shift mask. It is the chart showing the mode of change of the NILS value in each mask dimension when an isolated pattern is exposed with a chromeless type phase shift mask. It is the chart showing the optical image in each mask dimension at the time of exposing an isolated pattern with a chromeless type phase shift mask.

Explanation of symbols

101, 201, 701, 801, 901, 1001, 1001, 1101, 1201 Transparent substrate 102, 702, 902, 1102 Phase shift units 103, 703, 903, 1103, 1202 and transmittance adjustment films 104, 203, 704, 804 1204 Phase shifter film 202, 802, 1002 Transmittance adjusting film 204, 205, 803, 805, 806, 1003, 1004, 1203, 1205 Electron beam resist 1401 Chromeless type phase shift mask 1402 Halftone type phase shift mask 1403 Transmission part C Translucent film part S Phase shift part W Pattern width

Claims (7)

A chromeless type phase shift mask that gives a phase difference to the transmitted exposure light and improves the resolution by utilizing the mutual interference of the transmitted exposure light,
A transparent substrate;
A phase shift part formed on the transparent substrate;
A transmittance adjusting unit that is formed adjacent to the phase shift unit and lowers the transmittance of the exposure light; and
The transmittance adjusting unit has a phase shift of 2nπ (n = 0, 1, 2, 3...) With respect to exposure light.   The transmittance adjusting unit is formed of a transmittance adjusting film that adjusts the transmittance of incident light, and a phase shifter film that shifts the phase by 2nπ (n = 0, 1, 2, 3,...). The phase shift mask according to claim 1.   3. The phase shift mask according to claim 1, wherein the phase shift portion has a trench shape dug into the transparent substrate with a phase difference of 180 degrees with respect to the exposure light.   3. The phase according to claim 1, wherein the phase shift portion is formed by depositing a phase shifter film having a phase difference of 180 ° with respect to the exposure light on the transparent substrate. Shift mask.   5. The phase shift mask according to claim 4, wherein the phase shifter film constituting the phase shift portion and the phase shifter film constituting the transmittance adjusting film are made of the same material. The material of the transmittance adjusting film is made of tantalum silicide (TaSi), zircon silicide (ZrSi), molybdenum silicide (MoSi), chromium fluoride (CrF), silicon oxide (SiO ₂ ), and silicon oxynitride (SiON). 6. The phase shift mask according to claim 2, wherein any one selected from a group is used. A pattern exposure method by an exposure process using a phase shift mask,
The phase mask has a transmittance adjusting unit having a phase difference of 2nπ (n = 0, 1, 2, 3...) Between the phase shift unit corresponding to the fine pattern and the exposure light adjacent thereto on the transparent substrate. Formed,
A pattern exposure method using a phase shift mask, wherein an optical contrast value of a pattern formed on a resist is increased by selecting an optimal size of the transmittance adjusting unit for the size of the phase shift unit.

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