JP2003330159A - Transmission type phase shifting mask and pattern forming method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission type phase shifting mask which enhances the intensity of light contributing to a phase shifting effect and can ensure a large focal depth and to provide a pattern forming method. <P>SOLUTION: Both a portion on which a resist is left (space portion 4) and a portion from which a resist is removed and in which a vacant pattern such as a contact hole or groove wiring is formed (hole pattern portion 3) are formed with a transparent glass substrate 1, the glass substrate 1 in the portion on which a resist is left is hollowed by etching to vary the thickness of the glass substrate 1 in such a way that the phase difference between the portion on which a resist is left and the portion from which a resist is removed becomes 180°, and when the pattern size of the portion from which a resist is removed is large, a metallic film of light shielding Cr 2 or the like is formed on the inside of a pattern in such a way that the distance from the edge becomes ≤0.1 μm. By such a constitution, the intensity of light contributing to a phase shifting effect is enhanced and a large focal depth can be ensured. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission type phase shift mask and a pattern forming method using the transmission type phase shift mask.

[0002]

2. Description of the Related Art In recent years, with the high integration and miniaturization of semiconductor devices, various masks capable of forming fine patterns, for example, phase shift masks having a halftone film provided on a glass substrate have been developed. .

Here, a conventional phase shift mask and a pattern forming method using the phase shift mask will be described with reference to FIGS. 9 and 10 are diagrams showing the structure of a conventional phase shift mask, and FIGS. 11 and 12 are diagrams showing the structure of a positive resist pattern formed by the conventional phase shift mask. In addition, FIG.
FIG. 14 is a diagram showing a pattern forming method using a conventional phase shift mask, and FIG. 14 is a process sectional view showing a conventional phase shift mask manufacturing method.

Conventionally, a halftone phase shift mask has been used to form a fine pattern such as a contact hole pattern. As shown in FIGS. 9 and 10, this halftone phase shift mask has a halftone having an opening on a transparent substrate such as a glass substrate 1 at a portion corresponding to a hole pattern portion 3 such as a contact hole or groove wiring. The film 8 is provided and the contrast and focus margin of the pattern are improved by utilizing the phase shift effect of the halftone film 8.

A method for forming a pattern using such a conventional halftone phase shift mask is shown in FIG.
Will be described with reference to.

As shown in FIG. 13A, when a halftone phase shift mask is arranged on a semiconductor substrate 5 coated with a positive resist 9 and exposed, the exposure light is not attenuated in the hole pattern portion 3. Although it is transparent (the solid line arrow in the figure), the halftone film 8 is exposed except in the hole pattern portion 3.
The intensity of light transmitted by is attenuated by about 6%, and the phase is inverted by 180 ° (broken line arrow in the figure). Then, the light transmitted through the halftone film 8 interferes with the light transmitted through the hole pattern portion 3, and the phase shift effect causes a light intensity distribution on the wafer as shown in the figure.

Then, by using the positive resist 9 as the resist, the resist in the region where the light intensity is large corresponding to this light intensity distribution is removed by the development, and FIG.
A contact hole pattern as shown in FIG. 1, FIG. 12 and FIG. 13B can be formed.

Such a conventional halftone phase shift mask is manufactured by the method shown in FIG. First, as shown in FIG. 14A, a halftone film 8 for reversing the phase is formed on the glass substrate 1, and Cr is formed thereon.
After forming a light-shielding metal film (light-shielding Cr2) for example, a resist film 7a is applied on the entire surface, and a circuit pattern is drawn by using an electron beam exposure apparatus.

Next, as shown in FIG. 14B, the resist film 7a on which the circuit pattern is drawn is developed to form a resist pattern. Then, after the exposed light-shielding Cr2 is removed by dry etching or the like using the resist film 7a as a mask, the halftone film 8 is removed by dry etching or the like using the light-shielding Cr2 as a mask as shown in FIG. 14C. . Thereafter, as shown in FIG. 14D, the light shielding Cr2 is removed by dry or wet etching, and the halftone phase shift mask is completed.

[0010]

However, in the above-mentioned conventional halftone phase shift mask, the light contributing to the phase shift effect is the light transmitted through the halftone film 8, and the halftone film 8 has a light intensity of 6%. Since it is attenuated to about 100%, a large size, for example, 130 nm
The effect required to obtain a wide depth of focus was not obtained with a moderate hole pattern. This is because the light contributing to the phase shift effect is attenuated by passing through the halftone film 8.

The present invention has been made in view of the above problems, and its main purpose is to enhance the intensity of light contributing to the phase shift effect and to obtain a wide depth of focus. Another object of the present invention is to provide a pattern forming method using the transmission type phase shift mask.

[0012]

In order to achieve the above-mentioned object, the transmission type phase shift mask of the present invention comprises:
The first region where the resist is left and the second region where the resist is removed to form a contact hole or a groove wiring are both formed of glass having different thicknesses, and the first region and the second region are formed. The thickness of the glass is set so that the phases differ by 180 °.

In the present invention, it is preferable that the first region is formed by etching a glass substrate, or the second region is formed by depositing a transparent member on the glass substrate.

Further, in the present invention, a metal film is formed on a region having a pattern size larger than a predetermined size in the second region with a predetermined distance from the edge of the region and inside the second region. The predetermined interval can be set to 0.1 μm or less.

Further, in the pattern forming method of the present invention, the first region on the mask where the resist is left and the second region where the resist is removed to form the contact hole or the groove wiring are made of glass having different thicknesses. The contact is formed by using a negative resist and a transmission type phase shift mask that is formed and has a thickness of the glass so that the first region and the second region have a phase difference of 180 °. A hole or the groove wiring is formed.

As described above, in the transmission type phase shift mask of the present invention, a portion where the resist is left (first area) and a portion where the resist is removed to form a cut pattern such as a contact hole or groove wiring (second area). Area (first area) in which both of the areas) are formed of transparent glass and the resist is left.
By etching the glass of, and setting the thickness of the glass so that the phase difference of the transmitted light between the first region and the second region is 180 °, the light intensity contributing to the phase shift effect is increased. , A wide depth of focus can be obtained.

Further, a portion (second
Area) is larger than a predetermined size, the inside is covered with a light shielding metal film such as Cr, and the distance between the edge of the pattern and the edge of the light shielding metal film is 0.1 μm or less. As a result, even a hole pattern having a large size can be accurately formed.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION In a preferred embodiment of the transmission type phase shift mask according to the present invention, a portion where the resist is left (the space portion 4 in FIG. 1) and the resist are removed to make contact holes, groove wiring, etc. Both of the portion (hole pattern portion 3 in FIG. 1) where the blank pattern is formed are formed of a transparent glass substrate, and the portion of the glass substrate where the resist is left is etched and dug to form the portion where the resist is left and the resist. If the thickness of the glass substrate is changed so that the phase difference of the part to be removed becomes 180 ° and the pattern size of the part to remove the resist is large, the distance from the edge to the inside of the pattern is 0.1 μm or less. A light-shielding metal film such as Cr is formed so that the light intensity contributing to the phase shift effect is increased. A wide depth of focus can be obtained even with a large size hole pattern.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 1 to 8 in order to describe the above-described embodiment of the present invention in more detail. 1 and 2 are a sectional view and a plan view showing the structure of a transmission type phase shift mask according to an embodiment of the present invention, and FIGS. 3 and 4 are formed by the transmission type phase shift mask of the present embodiment. It is a figure which shows the resist pattern of the formed negative resist. 5 is a diagram showing a pattern forming method using the transmission type phase shift mask of this embodiment, and FIGS. 6 and 7 are diagrams showing the effect of this embodiment. In addition, FIG. 8 is a process cross-sectional view showing the method of manufacturing the transmission type phase shift mask of this embodiment.

As shown in FIGS. 1 and 2, in the transmission type phase shift mask of this embodiment, both the space portion 4 for forming a resist and the hole pattern portion 3 for forming a contact hole or groove wiring are formed on the glass substrate 1. And the thickness of the glass substrate 1 is adjusted by etching the glass substrate 1 in the space portion 4 so that a phase difference of 180 ° is generated between the space portion 4 and the hole pattern portion 3. In a portion where a large area punching pattern is formed, a light-shielding Cr2 is arranged on the punching pattern so that the glass protrusion width is 0.1 μm or less.

In the transmission type phase shift mask constructed as described above, as shown in FIG. 5, the light transmitted through the hole pattern portion 3 and having the phase inverted by 180 ° interferes with the light transmitted through the space portion 4. Due to the phase shift effect, a light intensity distribution with high contrast as shown in the figure can be obtained.
Then, by using the negative resist 6 as the resist, the hole pattern portion 3 corresponding to this light intensity distribution is obtained.
The negative resist 6 is removed by development, and a highly accurate contact hole pattern as shown in FIGS. 1, 2 and 5B can be formed.

Further, since it is not possible to shield a wide area with a glass pattern having a phase difference and it is not possible to form a large area punching pattern, in the present embodiment, a large area punching pattern portion on the glass substrate 1 is formed. The light-shielding Cr so that the distance from the edge of the pattern is 0.1 μm or less.
A metal film such as 2 is provided. Note that the metal film is not limited to Cr, and any metal that can be used as a light shielding material for a mask can be used.

The light intensity and the depth of focus when the transmission type phase shift mask having the above structure is used will be described with reference to FIGS. 6 and 7. FIG. 6 shows the pattern resolution light intensity of the annular illumination with NA 0.60 (circle in the figure), NA 0.68 (square in the figure), and NA 0.75 (triangle in the figure) and the glass protrusion width (large area removal pattern). It is a figure which shows the relationship between the edge and the distance of light-shielding Cr2. As can be seen from FIG. 6, the pattern is transferred when the width of the glass protrusion is large, but the pattern is transferred when the width of the glass protrusion is 0.1 μm or less.
It can be seen that a large area blank pattern can be formed without being transferred regardless of the value of A.

FIG. 7 shows the focus characteristics of the phase shift mask having the conventional structure and the transmission type phase shift mask of this embodiment. As can be seen from the figure, the transmissive phase shift mask of the present example can maintain the pattern accuracy in a wide focus range, and it can be seen that the depth of focus is expanded by using this transmissive phase shift mask. .

Such a transmission type phase shift mask is shown in FIG.
It can be manufactured by the method shown in. Specifically, first, in FIG. 8A, light-shielding Cr2 is formed on the glass substrate 1.
After forming a metal film for light shielding such as
After applying a and drawing a circuit pattern, a resist film 7
a is developed to form a resist pattern (FIG. 8B).
reference).

Next, after the light-shielding Cr2 is removed by dry etching or the like using the resist film 7a as a mask, FIG.
As shown in (c), the glass substrate 1 is dug by dry etching or the like using the light-shielding Cr2 as a mask. The depth at this time is set so that the phase difference of the transmitted light between the etched portion and the non-etched portion is 180 °, but is about 190 nm in this embodiment.

Next, as shown in FIG. 8D, the resist film 7b is applied again on the glass substrate 1 to draw the pattern of the light-shielding Cr2, and then the resist film 7b is developed (FIG. 8).
(See (e)). Then, as shown in FIG. 8F, the light-shielding Cr2 within a range of 0.1 μm or less from the edge is removed by dry etching or the like using the resist film 7b as a mask,
The transmission type phase shift mask of this example is completed.

As described above, in the phase shift mask having the structure shown in the conventional example, the light contributing to the phase shift effect is light whose intensity is attenuated by about 6%, but in the structure of this embodiment, the hole is generated. Since the pattern portion 3 is also formed of the glass substrate 1, the intensity of light that contributes to the phase shift effect is approximately 10
It can be 0%. Thereby, the depth of focus can be increased and the hole pattern can be accurately formed.

Further, in this embodiment, since the negative resist is applied to the pattern formation and the light-shielding Cr is arranged in the large-area punched pattern portion, the pattern can be accurately formed even if the size of the punched pattern is large. Can be formed.

In the above embodiment, as a method of providing a phase difference between the space portion 4 and the hole pattern portion 3, the glass substrate 1 in the space portion 4 is dug by etching, but the present invention is not limited to the above embodiment. However, the space pattern 4 and the hole pattern part 3 are both formed of a light transmissive material, and the hole pattern part 3 has a light transmissive member as long as the phase difference between them is 180 °. Can also be configured to be deposited.

[0031]

As described above, according to the transmission type phase shift mask and the pattern forming method using the transmission type phase shift mask of the present invention, the depth of focus can be increased and the hole pattern can be accurately formed. Can be well formed.

The reason is that by using a negative resist for pattern formation and arranging glass whose phase is changed by 180 ° in the hole pattern portion, it is possible to increase the light contributing to the phase shift effect.

Further, by disposing the light-shielding Cr in the large area cut pattern portion, it is possible to prevent the resist from remaining in the large area cut pattern portion.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing a structure of a transmission type phase shift mask according to an embodiment of the present invention.

FIG. 2 is a plan view schematically showing the structure of a transmission type phase shift mask according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view showing the shape of a resist pattern formed by a transmission type phase shift mask according to an embodiment of the present invention.

FIG. 4 is a plan view showing the shape of a resist pattern formed by a transmission type phase shift mask according to an embodiment of the present invention.

FIG. 5 is a diagram showing a pattern forming method using a transmission type phase shift mask according to an embodiment of the present invention.

FIG. 6 is a diagram showing an effect of a transmission type phase shift mask according to an embodiment of the present invention.

FIG. 7 is a diagram showing an effect of the transmission type phase shift mask according to the embodiment of the present invention.

FIG. 8 is a process sectional view showing the method of manufacturing the transmission type phase shift mask according to the embodiment of the present invention.

FIG. 9 is a sectional view showing the structure of a conventional phase shift mask.

FIG. 10 is a plan view showing the structure of a conventional phase shift mask.

FIG. 11 is a cross-sectional view showing the shape of a resist pattern formed by a conventional phase shift mask.

FIG. 12 is a plan view showing the shape of a resist pattern formed by a conventional phase shift mask.

FIG. 13 is a diagram showing a pattern forming method using a conventional phase shift mask.

FIG. 14 is a process cross-sectional view showing the method of manufacturing a conventional phase shift mask.

[Explanation of symbols]

1 glass substrate 2 Light-shielding Cr 3 hole pattern section 4 space section 5 Semiconductor substrate 6 Negative resist 7a, 7b resist film 8 Halftone film 9 Positive resist

Claims (6)

[Claims] 1. A first region on a mask where a resist is left and a second region where a resist is removed to form a contact hole or a groove wiring are both formed of glass having different thicknesses,
Moreover, the phase between the first region and the second region is 18
A transmission type phase shift mask, wherein the thickness of the glass is set so as to differ by 0 °. 2. The transmission according to claim 1, wherein the first region is formed by etching a glass substrate, or the second region is formed by depositing a transparent member on the glass substrate. Type phase shift mask. 3. A metal film is formed on a region having a pattern size larger than a predetermined size in the second region, and a metal film is formed inside the second region at a predetermined interval from an edge of the region, and the predetermined film is formed. The transmissive phase shift mask according to claim 1 or 2, wherein the interval is set to 0.1 µm or less. 4. A first region on the mask where a resist is left and a second region where the resist is removed to form a contact hole or a groove wiring are both formed of glass having different thicknesses,
Moreover, the phase between the first region and the second region is 18
A pattern forming method characterized in that the contact hole or the groove wiring is formed using a negative resist and a transmission type phase shift mask in which the thickness of the glass is set so as to differ by 0 °. 5. The transmission type phase shift mask comprises:
5. The pattern forming method according to claim 4, wherein the region is formed by etching a glass substrate, or the second region is formed by depositing a transparent member on the glass substrate. 6. The transmission type phase shift mask comprises:
In the above area, a metal film is formed on an area having a pattern size larger than a predetermined size with an interval of 0.1 μm or less from the edge of the area and inside thereof. Item 4. The pattern forming method according to Item 4 or 5.