JPH07152140A - Production of halftone type phase shift mask - Google Patents

Abstract

PURPOSE:To provide a process for production of a halftone type phase shift mask with which mask patterns imparted with biases for improving the depth of focus are obtainable by a relatively simple method without using intricate techniques such as conversion of EB data. CONSTITUTION:A method for forming a film necessary for constituting light translucent parts on a transparent substrate 1 and forming the mask patterns consisting of light transmissive parts and the light translucent parts by a photolithography method in these parts is used as a method for forming the mask patterns imparted with the biases. Light shielding film patterns 2 having the sizes complying with the design value of the mask are formed on this transparent substrate 1 as the mask for exposing in this photolithography method. A photoresist 5a formed in the sections formed with the films 4a necessary for constituting the light translucent parts is subjected to overexposing by using this mask for exposing, by which the mask patterns imparted with the biases are formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a mask pattern composed of a light-transmitting portion and a light-semitransmitting portion so that the phases of the light passing therethrough are different from each other so that the light passing near the boundary portion thereof cancels each other out. The present invention relates to a method of manufacturing a halftone type phase shift mask which improves the contrast at the boundary.

[0002]

2. Description of the Related Art A mask pattern is one of photomasks for transferring a fine pattern in manufacturing a semiconductor LSI, and is particularly suitable for transferring an isolated pattern such as a single hole, dot or line. It is composed of a light transmitting part and a light semi-transmitting part, and the phases of the light passing through the two are made different so that the light passing through the vicinity of these boundaries cancels each other to improve the contrast of the boundaries. A halftone type phase shift mask is known (see, for example, Japanese Patent Application Laid-Open No. 4-136854).

However, although the above-mentioned halftone type phase shift mask can keep the contrast of the pattern boundary extremely excellent, from the viewpoint of the depth of focus of the transfer pattern, it is not always the case with a normal photomask. It has become clear that a sufficient depth of focus cannot be obtained.

As a method of increasing the depth of focus, a suitable bias is applied to the mask pattern, that is, the pattern of the light transmitting portion of the mask pattern is set to be larger than the original design size, whereby the depth of focus is greatly improved. A method has been proposed in which the effect of reducing the amount of exposure light is also obtained (for example, SOLID STATE TECHNO
LOGY (1992) 43-47).

[0005]

By the way, generally, in order to form a mask pattern of a halftone type phase shift mask, an electron beam resist is applied on a semitransparent film formed on a transparent substrate, and an electron beam resist is applied to this. A method is used in which electron beam exposure is performed using a line drawing device and development / etching processing is performed. In this case, the formed mask pattern is determined by EB data which is pattern data input to the electron beam drawing apparatus. Therefore, in this method, in order to apply the bias for increasing the depth of focus described above,
It is necessary to perform data conversion for biasing the EB data representing the original mask pattern.

However, since this EB data often has tens of millions of figures, there is a problem that it takes a lot of time for the data conversion. For example, it usually takes ten hours or more to convert EB data of about 20 million figures. Moreover, in the case of larger data,
There may be a case where conversion is not possible due to problems such as the disk capacity of the data converter.

The present invention has been made under the background described above, and imparts a bias for improving the depth of focus by a relatively simple method without using a complicated method such as conversion of EB data. It is an object of the present invention to provide a method of manufacturing a halftone type phase shift mask that can obtain the mask pattern thus obtained.

[0008]

In order to solve the above-mentioned problems, a method of manufacturing a halftone type phase shift mask according to the present invention comprises (Structure 1) a mask for performing fine pattern exposure, which comprises: The mask pattern formed on the surface is composed of a light transmissive portion that transmits light having an intensity that substantially contributes to exposure and a light semi-transmissive portion that transmits light that does not substantially contribute to exposure, and By making the phase of the light passing through the light semi-transmissive portion different from the phase of the light passing through the light transmissive portion, the light passing through the vicinity of the boundary between the light transmissive portion and the light semi-transmissive portion may cancel each other. A halftone type phase shift mask which is configured to obtain a transfer pattern capable of maintaining good contrast at the boundary,
The mask pattern is biased to set the pattern shape dimension of the light transmitting portion larger than the original dimension defined by the transfer pattern dimension, thereby improving the depth of focus during the transfer. In the manufacturing method of the halftone type phase shift mask for manufacturing the halftone type phase shift mask,
As a method of forming the mask pattern to which the bias is applied, a film necessary for forming the light semi-transmissive portion is formed on the transparent substrate, and a light transmissive portion and a light semi-transmissive portion are formed on this portion by photolithography. And a low-transmittance film having a size according to the original pattern size defined by the transfer pattern size on the transparent substrate as an exposure mask in the photolithography method. A pattern or a light-shielding film pattern is formed, and an exposure mask in which the exposure pattern is regulated by the low-transmittance film pattern or the light-shielding film pattern is formed. Exposing the photoresist formed in the area where the film required for construction is formed to a higher exposure than the normal exposure The mask pattern to which the bias is applied is formed by performing overexposure to be performed. As an aspect of this configuration 1, (configuration 2) a method for manufacturing a halftone phase shift mask of configuration 1 In the above-mentioned light semi-transmissive portion, the light transmittance is mainly formed by one or more low transmittance films formed on one or both of the front surface which is one surface of the transparent substrate and the back surface which is the other surface. And a part of the transparent substrate under the low-transmittance film in the thickness direction mainly has a phase-shifting function, and the light-transmissive portion is the transparent substrate. And a method of manufacturing the halftone phase shift mask of Configuration 1, wherein the region is partially removed in the thickness direction. In the above, the semi-transmissive portion mainly transmits light by one or more low transmittance films formed on either or both of the front surface which is one surface of the transparent substrate and the back surface which is the other surface. And a high-transmittance film formed above or below the low-transmittance film mainly serves to perform a phase shift function. The structure is characterized in that it is composed of a region in which the refractive index film and the high transmittance film are removed. Further, as a mode of this structure 3, (configuration 4) halftone phase of configuration 3 In the method for manufacturing a shift mask, the exposure mask has a pattern in which a first low-transmittance film formed on a surface of the transparent substrate has a size according to an original pattern size defined from the transfer pattern size. Forming The exposure pattern is controlled by the low-transmittance film pattern described above, and the exposure in the photolithography method sequentially includes a second low-transmittance film and a phase shift function on the low-transmittance film pattern. After forming the high-transmittance film and the photoresist film, the over-exposure is performed from the back surface side of the transparent substrate toward the photoresist through the low-transmittance film pattern, and the light-transmitting portion and the light are used. The mask pattern including the semi-transmissive portion is formed by sequentially using the resist pattern formed by applying the bias by the overexposure as an etching mask, and sequentially forming the high transmittance film and the second film.
Of the low-transmittance film, or by sequentially etching a part of the high-transmittance film, the second low-transmittance film and the low-transmittance film pattern, the exposure mask The low-transmittance film pattern used as a pattern for regulating the exposure pattern of is used as at least a part of a film having a light-transmittance control function of the light semi-transmissive portion, As an aspect of any one of Configurations 1 to 4, (Configuration 5) In the method of manufacturing a halftone phase shift mask according to any one of Configurations 1 to 4, an etching stopper film is formed on the transparent substrate. As a mode of this configuration 5, (configuration 6) In the method for manufacturing a halftone phase shift mask of configuration 5, the etching stopper The membrane is
A structure characterized by being composed of any one of tin oxide, antimony oxide, magnesium oxide, indium oxide, aluminum oxide, zinc oxide, gallium oxide, or a mixture or compound of two or more thereof. Further, as an aspect of any one of configurations 1 to 6, (configuration 7) in the method of manufacturing a halftone phase shift mask according to any one of configurations 1 to 6, the low transmittance film is chromium, molybdenum, or silicon. A structure characterized by being made of a film material having a film thickness of 600 nm or less, which is composed of either tantalum or tungsten, or a material containing two or more kinds of these elements as main components, and further has structures 3 and 4 As an aspect of (Structure 8), in the method for manufacturing a halftone phase shift mask according to Structures 3 and 4, the high transmittance film is And silicon as a main component, and a material containing any one or more of oxygen, nitrogen, carbon, and fluorine, or a material containing two or more of them, and a configuration 1 (Structure 9) In the method for manufacturing a halftone type phase shift mask according to Structure 1, the light semi-transmissive portion is formed of a film whose material itself has both a function of controlling light transmittance and a phase shift function. As a mode of this configuration 9, as a mode of this configuration 9, (Configuration 10) In the method of manufacturing a halftone phase shift mask of configuration 9, the light transmittance of the light semi-transmissive portion is controlled. The film that has both the function to perform and the function to shift the phase is one of tantalum, chromium, molybdenum, silicon, and tungsten, or two or more of these elements, and oxygen, nitrogen, carbon, and phosphorus. It is configured such that it is made of a material containing any one or more of these elements of boron.

[0009]

According to the configuration 1, the halftone phase shift mask having the biased mask pattern is obtained by adding or changing a slight number of steps to the conventional manufacturing steps without performing complicated data conversion. It is possible to rapidly manufacture.

According to Structure 2, the halftone type phase shift mask has a mask pattern to which a bias is applied, and the phase shift layer is formed by utilizing a part of the transparent substrate itself. It is possible to easily and quickly manufacture the halftone type phase shift mask.

According to the structure 3, a halftone type phase shift mask having a mask pattern to which a bias is applied, and a high transmittance film forming a phase shift layer is provided on a transparent substrate. It becomes possible to easily and quickly manufacture the halftone phase shift mask.

Further, according to the structure 4, the low-transmittance film pattern formed for over-exposure for applying the bias can be used as it is as a part of the semi-transmissive portion.

According to the constitutions 5 and 6, it is possible to prevent the transparent substrate from being damaged during etching, and moreover,
It is possible to secure a large degree of freedom in selecting the etching method.

According to the structures 7 and 8, a mask bias is applied, and a halftone type phase shift mask having sufficient performance can be obtained relatively easily.

According to the configurations 9 and 10, it is possible to obtain a halftone phase shift mask of the type in which a mask bias is applied and the light semi-transmissive portion is composed of a single film.

[0016]

【Example】

(Embodiment 1) FIG. 1 is a manufacturing process explanatory view of a method of manufacturing a halftone phase shift mask according to Embodiment 1 of the present invention. Hereinafter, Embodiment 1 will be described with reference to FIG. This example is an example in which the present invention is applied to the production of a halftone type phase shift mask of the type in which the phase shift layer is formed by using a part of the transparent substrate itself. Over-exposure the photoresist formed on the surface of the transparent substrate by forming a light-shielding film pattern having a size according to the original pattern size defined from the pattern size, and performing back exposure using this light-shielding film pattern as an exposure mask. This is an example of doing so.

In FIG. 1A, first, a transparent substrate 1 made of quartz glass has a thickness 1 on the back surface (the surface on the lower side in the drawing).
A light shielding film 2a made of a chromium film having a light transmittance of zero (optical density OD = 3) at 00 nm is formed by a sputtering method. Next, a positive type electron beam resist (Z
EP-7000; trade name of Nippon Zeon Co., Ltd.) is applied by a spin coating method to form an electron beam resist film 3a having a thickness of 500 nm. Next, the electron beam resist film 3a
In addition, a predetermined condition (5
Electron beam exposure is performed by drawing a predetermined pattern at (μC / cm ² , 20 kV, etc.). In this case, the EB data input to the electron beam drawing apparatus is data showing a size according to the original pattern size defined from the transfer pattern size to be transferred by the halftone type phase shift mask manufactured by the method of this embodiment. The pattern drawn by the electron beam drawing apparatus has a size (mask design value) according to the original pattern size defined from the transfer pattern size.

Next, as shown in FIG. 1B, the electron beam resist film 3a after electron beam exposure is developed with a predetermined developing solution to form an electron beam resist film pattern 3. Next, using the electron beam resist film pattern 3 as a mask, a mixed gas of chlorine and oxygen is used as an etching gas by a reactive ion etching device (RIE) not shown, and 500 W, 0.1 torr.
The light shielding film 2a made of chromium is etched under the condition of r to form the light shielding film pattern 2.

Next, as shown in FIG. 1C, the unnecessary electron beam resist film pattern 3 is peeled off with hot sulfuric acid, and then the surface opposite to the back surface on which the light shielding film pattern 2 is formed. The thickness of the transparent substrate 1 is 25 nm and the transmittance is 8
% (Wavelength 365 nm) chrome film with low transmittance film 4
a is formed by a sputtering method. Then, a positive photoresist (AZ-13) is formed on the low transmittance film 4a.
50; a trade name of Hoechst Japan Co., Ltd.) is applied by a spin coating method to form a photoresist film 5a having a thickness of 600 nm.

Next, as shown in FIG. 1D, a predetermined exposure light is applied from the entire back surface on which the light shielding film pattern 2 is formed to the photoresist film 5a using the light shielding film pattern 2 as an exposure mask. The photoresist film 5a is exposed to light, over-exposed by backside exposure to the photoresist film 5a, and developed to form a photoresist film pattern 5.

Here, overexposure means an object to be exposed,
In other words, an exposure amount (exposure time) larger than the exposure amount (exposure time) with which the photoresist film 5a can be exposed according to the size of the exposure mask, that is, the opening (exposure light passage region) of the light shielding film pattern 2 Exposure time). When the over-exposed photoresist film 5a is developed, the size of the region of the photoresist film 5a removed by the development becomes larger than the size (mask design value) of the opening of the light shielding film pattern 2. FIG. 2 shows the relationship between the exposure time and the mask design value under the conditions of Example 1. As shown in FIG. 2, the required mask bias can be applied by controlling the exposure time.

Next, as shown in FIG. 1E, the low transmittance film 4a is etched by reactive dry etching using the photoresist film pattern 5 as a mask,
The low transmittance film pattern 4 is formed. The dry etching conditions in this case are a mixed gas of chlorine and oxygen as an etching gas, a pressure of 0.1 torr, and a power of 50.
Set to 0W. Next, with the photoresist film pattern 5 and the low-transmittance film pattern 4 as a mask, the surface of the transparent substrate 1 is 350 nm deep by reactive dry etching.
To form a phase shift layer on the transparent substrate 1 itself. At this time, a mixed gas of CHF ₃ gas and oxygen is used as an etching gas, the pressure is 0.1 torr, and the power is 500 W.

Next, as shown in FIG. 1F, the photoresist film pattern 5 is removed with concentrated sulfuric acid, and the light-shielding film pattern 2 is 165 g of ceric ammonium nitrate.
And add pure water to 42 ml of perchloric acid (70%) and 1000 m
By spraying and removing only the light-shielding film pattern 2 with the etching solution made into 1 l, the light-semitransmissive part and the light-transmissive part are formed on the mask on the transparent substrate 1, and the phase shift part is formed on a part of the substrate. A halftone phase shift mask of the type to be constructed and to which a necessary mask bias is applied is obtained.

The basic performance of the thus-obtained halftone type phase shift mask as a mask is that of a conventional halftone type phase shift mask without applying a bias, or
The same performance as that of a conventional photomask using a conventional light-shielding film is shown, and the specific characteristics of the depth of focus are collectively shown in the section of the description of Example 2 described later. It has been confirmed that it also shows superior performance.

In the above-described embodiment, the light-shielding film 2a is formed on the back surface of the transparent substrate 1, and the light-shielding film pattern 2 is formed by patterning the light-shielding film 2a. 4a and a positive resist coating were applied to form the photoresist film 5a, but the light shielding film 2a, the low transmittance film 4a and the photoresist film 5a may be formed on the transparent substrate 1 from the beginning.

Further, in this embodiment, the method of controlling the exposure time for performing the overexposure for giving the necessary mask bias was shown, but this method keeps the exposure time constant and the light intensity of the exposure light (exposure Even if the amount) is increased or decreased, the same effect and line width controllability can be obtained.

In this embodiment, chromium is used as the low-transmittance film 2a, but this is made of any one of chromium, molybdenum, silicon, tantalum, and tungsten, or two or more of these elements as a main component. In this case, a trace amount of oxygen, nitrogen, fluorine, carbon, etc. may be contained as another component.

Further, in this embodiment, the example of the halftone type phase shift mask in which the light transmittance T of the light semi-transmissive portion is 8% is shown, but the light transmittance T of the light semi-transmissive portion is 0. 5-80
It can be anywhere between%.

(Embodiment 2) FIG. 3 is a process explanatory view of a method of manufacturing a halftone type phase shift mask according to Embodiment 2 of the present invention. The second embodiment will be described below with reference to FIG. It should be noted that this embodiment is the same as the first embodiment in that the present invention is applied to the manufacture of a halftone phase shift mask of the type in which the phase shift layer is formed by using a part of the transparent substrate itself. is there. However, in Example 1,
Form a light-shielding film pattern on the back surface of the transparent substrate, which has dimensions that match the original pattern dimensions defined by the transfer pattern dimensions, and form the light-shielding film pattern on the front surface of the transparent substrate by back exposure using this mask as an exposure mask. The exposed photoresist was overexposed and the light shielding film pattern was finally removed. In Example 2, the first low transmittance film pattern was used instead of the light shielding film pattern. The first low-transmittance film pattern is left without being finally removed, and the second low-transmittance film pattern formed on the surface thereof serves to control the light transmittance of the light semi-transmissive portion. This is the difference from Example 1. Therefore, the formation of the first low-transmittance film pattern is almost the same as the step of forming the light-shielding film pattern in the first embodiment, and therefore the illustration of this step will be omitted.

First, a first low transmittance film made of a chromium film having a thickness of 15 nm is formed on the back surface of the transparent substrate 21 made of quartz glass by a sputtering method. Then this first
Positive electron beam resist (ZEP-7
000; product name of Nippon Zeon Co., Ltd.) is applied by a spin coating method to form an electron beam resist film having a thickness of 500 nm. Next, the electron beam resist film is exposed by a predetermined pattern drawing under a predetermined condition (5 μC / cm ² , 20 kV, etc.) by an electron beam drawing apparatus. In this case, the EB data input to the electron beam drawing apparatus is data showing a size according to the original pattern size defined from the transfer pattern size to be transferred by the halftone type phase shift mask manufactured by the method of this embodiment. The pattern drawn by the electron beam drawing apparatus has a size (mask design value) according to the original pattern size defined from the transfer pattern size. Next, the exposed resist film is developed with a predetermined developing solution to form an electron beam resist pattern. Next, using this electron beam resist pattern as a mask, a mixed gas of chlorine and oxygen is used as an etching gas in a reactive ion etching apparatus (RIE), and
The first low transmittance film made of chromium is etched under the conditions of W and 0.1 torr, and the unnecessary resist is removed with hot sulfuric acid (not shown above).

As a result, the first low transmittance film pattern 22 is formed on the back surface of the transparent substrate 21 (see FIG. 3A).

Next, a second low transmittance film 24 made of a chromium film having a thickness of 15 nm is formed on the surface opposite to the patterned mask.
a is formed by a sputtering method, and a positive photoresist (AZ-13 is formed on the second low transmittance film 24a.
50; Hoechst Japan Co., Ltd. product name) is applied by a spin coating method to form a photoresist film 2 having a thickness of 600 nm.
5a is formed (see FIG. 3A).

Next, backside exposure is performed from the entire back surface side of the transparent substrate 21 using the first low transmittance film pattern 22 as a mask, and the unpatterned second low transmittance film 24a on the front surface side of the transparent substrate 21. The photoresist film 25a is over-exposed and developed to form a photoresist film pattern 25 (see FIG. 3B). in this case,
Providing the necessary mask bias by controlling the exposure time is the same as in the first embodiment.

Next, the photoresist film pattern 25 is formed.
Is used as a mask to etch the second low transmittance film 24a by reactive dry etching to form a second low transmittance film pattern 24. The dry etching condition in this case is to use a mixed gas of chlorine and oxygen as an etching gas,
The pressure is 0.1 torr and the power is 500W. Next, using the photoresist film pattern 25 and the low transmittance film pattern 24 as a mask, the quartz substrate is etched to a depth of 350 nm by reactive dry etching,
A phase shift layer composed of the transparent substrate 21 itself is formed (see FIG. 3C). At this time, the etching gas is a mixed gas of CHF ₃ and oxygen, and the pressure is 0.1 torr.
r, 500W.

After that, the photoresist film pattern 25 which is no longer needed is peeled off with hot nitric acid. As a result, the first low-transmittance film pattern 22 having the opening pattern according to the mask design value is formed on the back surface of the transparent substrate 21, and the second low-transmittance film pattern 24 having the necessary mask bias is formed on the front surface. The first low-transmittance film pattern 22 and the second low-transmittance film pattern 24 have a function of controlling the light transmittance of the light semi-transmissive portion and a phase shift function of the transparent substrate 21 itself. A halftone type phase shift mask of a type that is partially responsible can be obtained (FIG. 3).
(D)).

Also according to this embodiment, a halftone type phase shift mask having the same characteristics as those of the first embodiment can be obtained. Moreover, according to this embodiment, it is not necessary to remove the first low-transmittance film pattern formed as the overexposure exposure mask for applying the bias.
There is an advantage that one process can be omitted as compared with the first embodiment in which the light shielding film pattern needs to be removed.

Next, the above-described first embodiment (designated as mask A)
And the depth of focus between Example 2 (mask B) and a conventional halftone phase shift mask (mask C) having a mask pattern to which a bias is not applied and an ordinary photomask (mask D) using a light shielding film. The result of comparing the characteristics will be described. It should be noted that this comparison is performed by a computer simulation method assuming a condition similar to an actual condition.

The assumed conditions are as follows. First, each phase shift mask was used as a mask for a 1/5 reduction projection exposure apparatus (stepper). Further, the mask pattern in that case is an isolated contact hole (0.4 μm on the wafer) having a mask design value of a line width of 2 μm □. Further, as exposure conditions of the exposure device at the time of transfer, numerical aperture NA = 0.5 and incoherent ratio σ = 0.
3. The wavelength λ of the exposure light was λ = 365 nm, and the defocus amount DEFOCUS of the transfer image was assumed to be 0 μm as a reference. Figure 4
Shows the configuration and mask pattern dimensions of the masks A, B, C, and D to be compared. Further, FIG. 5 shows a light intensity profile on the transfer target wafer when transferred with the mask A (1 μm bias applied) and the mask B. In the following, the peak value of the light intensity of the profile shown in FIG. 5 is Imax, and the light intensity value of the dark part formed on both sides of the peak is Imin.

The comparison of the depth of focus characteristics is made by the dependence of Imax when the defocus amount (DEFOCUS) of the transfer image is changed,
Also, the contrast when changing DEFOCUS (C
and the degree of these dependencies is compared. It can be said that the smaller these dependencies are, the deeper the depth of focus is and the better the depth of focus characteristics are. As the contrast C, the one defined by the following equation was adopted.

C = (Imax−Imin) / (Imax + Imin) FIG. 6 shows the DEFOCUS of the masks A, B, C, and D which are comparison targets.
FIG. 7 is a graph showing the dependence of Imax on the contrast C, and FIG. 7 is a graph showing the dependence of the contrast C on the DEFOCUS of the masks A, B, C, and D to be compared.

As is apparent from FIGS. 6 and 7, the halftone type phase shift masks of Example 1 (mask A) and Example 2 (mask B) are conventional masks (mask C,
Very large Imax regardless of depth of focus compared to D)
And at the same time showing the relationship between DEFOCUS and C, DEFOCU
It can be seen that a relatively high contrast can be obtained even if S becomes large.

(Embodiment 3) FIG. 8 is a process explanatory view of a method of manufacturing a halftone phase shift mask according to Embodiment 3 of the present invention. The third embodiment will be described below with reference to FIG. Note that this example is an example in which the present invention is applied to the manufacture of a halftone phase shift mask of the type in which a high transmittance film having a phase shift function is formed on a transparent substrate separately from the transparent substrate. , Different from the first and second embodiments. In addition, in Example 2, the first formed on the back surface of the transparent substrate
In the third embodiment, the low-transmittance film pattern is formed on the surface so as to overlap the second low-transmittance film pattern, and each film is formed after forming the etching stopper film on the substrate surface. This is the difference from Example 2. However, other points are basically the same as in the first and second embodiments. Therefore, the illustration of the steps of forming the etching stopper film and forming the first low-transmittance film pattern will be omitted.

First, an etching stopper film 36 made of MgAl ₂ O _{4 -x} having a thickness of 20 nm is formed on the surface of a transparent substrate 31 made of quartz glass by using a mixed target of Mg and Al and a mixed gas of argon and oxygen. Created by reactive sputtering. Next, a first low-transmittance film made of a chromium film having a thickness of 15 nm is formed on the etching stopper film 36 by a sputtering method. Then, a positive electron beam resist (ZE) is formed on the first low transmittance film.
P-7000; trade name of Nippon Zeon Co., Ltd.) is applied by a spin coating method to form an electron beam resist film having a thickness of 500 nm. Next, the electron beam resist film was subjected to predetermined conditions (5 μC / cm ² , 20 k
(V, etc.) is used to perform exposure by drawing a pattern having a dimension according to the mask design value. Next, the resist film after the electron beam exposure is developed with a predetermined developing solution to form an electron beam resist pattern. Then, using this electron beam resist pattern as a mask, a reactive ion etching apparatus (RIE) was used, and a mixed gas of chlorine and oxygen was used as an etching gas.
The first low-transmittance film pattern 32 is formed by etching the first low-transmittance film made of a chromium film under the condition of 0.1 torr and removing the unnecessary resist with hot sulfuric acid.
Are formed (see FIG. 8A).

Next, a 15 nm-thick MoSi _x film is formed on the mask surface (surface) on which the first low-transmittance film pattern 32 is formed.
The second low-transmittance film 34a made of SiO ₂ is formed by the sputtering method, and a coating solution for forming a SiO ₂ film (Acuglass # 311; product name of Allied Signal Co., Ltd.) is formed thereon.
(Hereinafter referred to as SOG) is applied by a spin coating method and baked to form a high transmittance film (SOG film) 37a having a thickness of 360 nm.
To form. The high transmittance film 37a has a phase shift function. Next, a positive photoresist (AZ-1350; Hoechst Japan Co., Ltd. trade name) is applied onto the high transmittance film 37a by a spin coating method to form a photoresist film 38a having a thickness of 600 nm (FIG. 8
(See (B)).

Next, exposure light is irradiated from the back surface of the transparent substrate 31 on which no film is formed, and back exposure is performed using the first low-transmittance film pattern 32 of chromium as a mask.
This backside exposure is performed by unpatterned M on the front side.
Second low-transmittance film 34a and SOG made of oSi _x film
The photoresist film 38a is overexposed through the film 37a and developed to form a biased photoresist pattern 38. In this case, the required mask bias can be given with good controllability by controlling the exposure time.

Next, the SOG film 3 is formed by reactive dry etching using the photoresist pattern 38 as a mask.
The SOG film pattern 37 is formed by etching 7a. The dry etching conditions in this case are as follows: the etching gas is a mixed gas of CHF ₃ and oxygen, the pressure is 0.1 torr,
The power is 500W.

Next, by using the photoresist pattern 38 and the SOG film pattern 37 as a mask, the second low transmittance film 3 made of MoSi _{x is formed} by reactive dry etching.
4a is etched to form a second low transmittance film pattern 34 (see FIG. 8C). At this time, a mixed gas of CF ₄ and oxygen is used as an etching gas, the pressure is 0.2 torr, and the power is 500 W. In this case, the second low-transmittance film 34a made of MoSi _x is etched, but the first low-transmittance film pattern 32 made of Cr having sufficient resistance to this etching gas remains as it is.

Thereafter, the photoresist which is no longer needed is peeled off with hot sulfuric acid, so that the surface of the transparent substrate 1 is
A second low-transmittance film pattern having a biased pattern is formed on the first low-transmittance film pattern having a pattern having a size according to the mask design value, and the second low-transmittance film pattern has a light transmittance control function. In addition, a halftone type phase shift mask can be obtained in which the high transmittance film pattern formed on the second low transmittance film pattern has a phase shift function.

According to this embodiment, the same advantages as those of the above-mentioned embodiments can be obtained.

(Modification of Third Embodiment) FIGS. 9A to 9C are explanatory views of manufacturing steps of a modification of the third embodiment. This modification is the third embodiment.
In place of the first low-transmittance film pattern 32 made of Cr, the first low-transmittance film 321 made of MoSi _x .
Example 3 is the same as Example 3 except that was used. In this embodiment, the first low-transmittance film pattern 32 is formed so as to have the same pattern as the pattern of the second low-transmittance film 34a when the second low-transmittance film 34a is etched. The third embodiment is different from the third embodiment in that the parts are removed (FIG. 9C,
(D)). Also in this case, the same advantages as the third embodiment are obtained.

(Embodiment 4) FIG. 10 is an explanatory view of a manufacturing process of a halftone type phase shift mask according to Embodiment 4 of the present invention. The fourth embodiment will be described below with reference to FIG. Note that this embodiment is an example in which the present invention is applied to a halftone type phase shift mask in which the light semi-transmissive portion is made of a film whose material itself has both a function of controlling light transmittance and a phase shift function. is there.

First, a light shielding film made of a chromium film having a thickness of 100 nm and a light transmittance of zero (optical density OD = 3) is formed on the back surface of the transparent substrate 41 made of quartz glass by a sputtering method. Then, a positive type electron beam resist (ZEP-810s; trade name of Nippon Zeon Co., Ltd.) is applied on the light-shielding film by spin coating to give a thickness of 500 n.
An electron beam resist film of m is formed. Then, the electron beam resist film was subjected to predetermined conditions (5 μC
/ Cm ^2, to draw a pattern dimension as designed at 20kV etc.) subjected to exposure. Next, the electron beam resist film after exposure is developed with a predetermined developing solution to form an electron beam resist pattern. Then, using this electron beam resist pattern as a mask, a mixed gas of chlorine and oxygen is used as an etching gas in a reactive ion etching apparatus (RIE) at 500 W,
The light-shielding film of chromium is etched under the condition of 0.1 torr, and the unnecessary resist is removed with hot sulfuric acid. As a result, the light-shielding film pattern 42 having the pattern dimension according to the mask design value is formed on the back surface of the transparent substrate 41 (see FIG. 10A).

Next, the surface of the transparent substrate 41 has a thickness of 15 nm.
A conductive etching stopper film 46 composed of tin and antimony film is formed by sputtering.

Next, tantalum alkoxide (Ta (OC
A mixture of ₂ H ₅ ) ₄ ) and alcohol is applied by a spin coating method and baked, and the transmittance T is 8% at a thickness of 200 nm.
(365 nm) that also serves as a phase shift layer
A halftone film 47a made of O _x is formed (see FIG. 1).
0 (A)).

Next, a positive type photoresist (AZ-1350; trade name of Hoechst Japan Co., Ltd.) is applied onto the halftone film 47a by spin coating to give a thickness of 6
A photoresist film 48a having a thickness of 00 nm is formed (see FIG. 1).
0 (A)).

Next, a predetermined exposure light is irradiated from the back surface side on which the light shielding film pattern 42 is formed, and the photoresist film 48a is overexposed by the back surface exposure through the etching stopper film 46 and the halftone film 47a. A photoresist pattern 48 which is developed and biased is formed. In this case, the required mask bias can be applied by controlling the exposure time (see FIG. 1).
0 (A)).

Next, the halftone film 47a made of TaOx is etched by reactive dry etching using the photoresist pattern 48 as a mask. The dry etching conditions in this case are a mixed gas of etching gas CF ₄ and oxygen, a pressure of 0.1 torr, and 500 W.

Next, the remaining photoresist pattern 4
8 was removed with concentrated sulfuric acid, and the light-shielding film pattern 42 was formed with 165 g of ceric ammonium nitrate and perchloric acid (70
%) 42 ml of pure water is added to make 1000 ml of the etching solution and is sprayed and removed only on the light shielding film. Thereby, the light semi-transmissive portion and the light transmissive portion are formed on the mask on the transparent substrate 41, and the light semi-transmissive portion is composed of a single-layer film having both a phase shift function and a light transmittance control function. ,
It is easy to obtain a halftone phase shift mask in which a necessary mask bias is formed. This example also
In addition to the same advantages as those of the above-described embodiments, the advantage that the process can be simplified is obtained.

The material of the etching stopper film is
In addition to the materials listed in the above examples, for example, tin oxide, antimony oxide, magnesium oxide, indium oxide, aluminum oxide, zinc oxide, gallium oxide, or a mixture or compound of two or more thereof. Can be used.

The material of the low-transmittance film may be any one of chromium, molybdenum, silicon, tantalum, and tungsten, or a material containing two or more of these elements as its main components. Well, the film thickness is 60
The range may be 0 nm or less.

Further, the high-transmittance film may be made of a material containing silicon as a main component and oxygen, nitrogen, carbon, or fluorine, or a material containing two or more of these elements.

As the material of the film having both the function of controlling the light transmittance of the light semi-transmissive portion and the phase shift function, any one of tantalum, chromium, molybdenum, silicon and tungsten, or two or more kinds of these materials can be used. A material obtained by adding any one of oxygen, nitrogen, carbon, boron, and fluorine or two or more of these elements to an element can be used.

Although hot sulfuric acid was used for stripping the resist in each of the above-mentioned embodiments, a simple organic or inorganic treatment liquid may be used.

Although the spin coat method was used for forming the high-transmittance film and the halftone film having the phase shift function, a reactive sputtering method, a vapor deposition method, a CVD method or the like may be used.

Further, in each of the examples, dry etching using a mixed gas of chlorine and oxygen was used for the etching of Cr, but the etching gas is chlorine, HBr, HCl, BCl.
₃ , CH ₃ Cl, SiCl _4, etc. may be used singly or in a mixture of two or more kinds, or in addition to these, a gas such as oxygen, nitrogen, hydrogen, He, argon or the like or a mixture of two or more kinds may be used. Alternatively, wet etching using the etching solution used for peeling off the light shielding film Cr may be used.

MoSi _x is etched with CF ₄ · oxygen,
SOG etching showed dry etching with a mixed gas of CHF ₃ and oxygen, but in each case, CF ₄ , CHF ₃ ,
_{C 2 F 6, NF 3,} C 3 F 8, CH 2 F 2, alone or in a mixed gas such as SF _6, or they oxygen, hydrogen, nitrogen, He, alone or two or argon, etc. A mixture of the above may be added and used.

Incidentally, tantalum, which is not shown in each embodiment,
Chromium, molybdenum, silicon, tungsten alone, or a film obtained by adding oxygen, nitrogen, carbon, boron, fluorine alone or two or more of these elements to these two or more elements, is also a combination of the above gases. Are more easily etched. The film containing Cr can be easily etched with an etching solution in which pure water is added to 165 g of ceric ammonium nitrate and 42 ml of perchloric acid (70%) to make 1000 ml.

In many cases, the materials shown in this embodiment have no or low conductivity because of their high transparency. In that case, the etching stopper has conductivity, the electron beam resist is mixed with a conductive polymer, an organic conductive film is provided above or below the electron beam resist, or a metal such as aluminum, molybdenum, or MoSix is used. You may use a thin film as a charge-up prevention film at the time of electron beam drawing. The charge-up prevention film can be peeled off by a predetermined peeling method.

In the above embodiment, electron beam exposure was used to form a resist pattern as designed, but other exposure methods may be used. In this case, a resist suitable for the exposure method is used. Of course.

[0070]

As described above in detail, the halftone phase shift mask according to the present invention is used for forming a light semi-transmissive portion on a transparent substrate as a method for forming a mask pattern to which a bias is applied. By using a method of forming a required film and forming a mask pattern consisting of a light transmissive portion and a light semi-transmissive portion by a photolithography method in this portion, as a mask for exposure in this photolithography method, on a transparent substrate, A photo formed on a portion where a film necessary for forming the light semi-transmissive portion is formed by forming a low-transmittance film pattern or a light-shielding film pattern having dimensions according to the mask design value. By exposing the resist to an overexposure in which the exposure amount is larger than the normal exposure amount, the biased mask pattern is formed. With this, it is possible to obtain a biased mask pattern for improving the depth of focus by a relatively simple method without using a complicated method such as conversion of EB data. The manufacturing method of the mold phase shift mask is obtained.

[Brief description of drawings]

FIG. 1 is a manufacturing process explanatory diagram of a method of manufacturing a halftone phase shift mask according to a first embodiment of the present invention.

FIG. 2 is a graph showing the relationship between the exposure time and the mask design value.

FIG. 3 is a manufacturing process explanatory diagram of the manufacturing method of the halftone phase shift mask according to the second embodiment of the present invention.

FIG. 4 is a diagram showing a configuration of masks A, B, C, and D and mask pattern dimensions.

FIG. 5 is a diagram showing a light intensity profile on a transfer target wafer when transferred using a mask A (a bias of 1 μm is applied) and a mask B.

6] DEFOCUS and I for masks A, B, C and D
It is a graph which shows the simulation result of the relationship with max.

FIG. 7 is a graph showing the relationship between DEFOCUS and contrast C for masks A, B, C and D.

FIG. 8 is a manufacturing process explanatory diagram of the method of manufacturing the halftone phase shift mask according to the third embodiment of the present invention.

FIG. 9 is a manufacturing process explanatory diagram of the method of manufacturing the halftone phase shift mask according to the modification of the third embodiment of the present invention.

FIG. 10 is a manufacturing process explanatory diagram of the method of manufacturing the halftone phase shift mask according to the example of the present invention.

[Explanation of symbols]

1 ... Transparent substrate, 2 ... Shading film pattern, 2a ... Shading film, 3
Electron beam resist film pattern, 3a Electron beam resist film, 4 ... Low transmittance film pattern, 4a ... Low transmittance film, 5 ...
Photoresist film pattern, 5a ... Photoresist film.

Claims (10)

[Claims] 1. A mask for performing fine pattern exposure, comprising a mask pattern formed on the surface of a transparent substrate,
The light transmitting portion that transmits the light having the intensity that substantially contributes to the exposure and the light semi-transmissive portion that transmits the light that does not substantially contribute to the exposure are formed. By making the phase and the phase of the light passing through the light transmitting portion different from each other, the light passing through the vicinity of the boundary between the light transmitting portion and the light semi-transmitting portion cancels each other to improve the contrast of the boundary portion. A halftone type phase shift mask capable of obtaining a transfer pattern which can be held, wherein the mask pattern is set to have a dimension of a pattern shape of the light transmitting portion larger than an original dimension defined from the transfer pattern dimension. Halftone type which manufactures a halftone type phase shift mask in which the depth of focus at the time of transfer is improved by applying a bias. In the method for manufacturing a phase shift mask, as a method of forming the biased mask pattern, a film necessary for forming the light semi-transmissive portion is formed on the transparent substrate, and a photolithography method is applied to this portion. A method for forming a mask pattern composed of a light transmitting portion and a light semi-transmitting portion is used, and as the exposure mask in this photolithography method, the transparent substrate is provided with an original pattern dimension defined by the transfer pattern dimension. Forming a low-transmittance film pattern or a light-shielding film pattern having a dimension of, and forming an exposure mask in which the exposure pattern is regulated by the low-transmittance film pattern or the light-shielding film pattern. A photoresist formed on a portion where a film necessary to form the light semi-transmissive portion is formed using A method of manufacturing a halftone type phase shift mask, characterized in that the mask pattern to which the bias is applied is formed by performing overexposure in which the strike is exposed with an exposure amount larger than a normal exposure amount. 2. The method of manufacturing a halftone phase shift mask according to claim 1, wherein the light semi-transmissive portion is one of a front surface of the transparent substrate and a back surface of the other surface. Alternatively, one or more low-transmittance films formed on both sides have a function of mainly controlling the light transmittance, and a phase shift is mainly caused by a part of the transparent substrate under the low-transmittance film in the thickness direction. The half-tone phase shifter is configured to have a function, and the light transmitting portion is configured by a region in which the transparent substrate is partially removed in a thickness direction. Mask manufacturing method. 3. The method of manufacturing a halftone phase shift mask according to claim 1, wherein the light semi-transmissive portion is one of a front surface and a back surface of the transparent substrate. Alternatively, one or more low-transmittance films formed on both sides have a function of mainly controlling the light transmittance, and a high-transmittance film formed above or below the low-transmittance film mainly serves as a phase shift function. The half-tone phase is characterized in that the light transmitting portion is constituted by a region where the low transmittance film and the high transmittance film are removed. Shift mask manufacturing method. 4. The method of manufacturing a halftone type phase shift mask according to claim 3, wherein the exposure mask is formed on the first low transmittance film formed on the surface of the transparent substrate, and the transfer pattern is formed on the first low transmittance film. The exposure pattern is constituted by a low-transmittance film pattern formed with a pattern having a size according to the original pattern size defined by the size, and the exposure in the photolithography method is performed by exposing the low-transmittance film pattern. A second low-transmittance film, a high-transmittance film having a phase shift function, and a photoresist film are sequentially formed on the back surface of the transparent substrate toward the photoresist through the low-transmittance film pattern. From the overexposure, and the mask pattern composed of the light transmissive portion and the light semitransmissive portion is exposed by the overexposure. The high transmittance film and the second low transmittance film are sequentially etched by using the resist pattern formed by applying ashes as an etching mask, or the high transmittance film and the second low transmittance film are sequentially etched. And a low-transmittance film pattern formed by etching a part of the low-transmittance film pattern, wherein the low-transmittance film pattern used as a pattern for regulating the exposure pattern of the exposure mask is used for the light transmission of the light-semitransmissive portion. A method of manufacturing a halftone phase shift mask, characterized in that it is used as at least a part of a film having a rate control function. 5. The method of manufacturing a halftone phase shift mask according to claim 1, wherein an etching stopper film is formed on the transparent substrate. Shift mask manufacturing method. 6. The method of manufacturing a halftone phase shift mask according to claim 5, wherein the etching stopper film is any of tin oxide, antimony oxide, magnesium oxide, indium oxide, aluminum oxide, zinc oxide and gallium oxide. Or a method of manufacturing a halftone type phase shift mask, characterized by comprising a mixture or compound of two or more kinds thereof. 7. The method of manufacturing a halftone phase shift mask according to claim 1, wherein the low transmittance film is any one of chromium, molybdenum, silicon, tantalum, and tungsten, or those. Film thickness composed of a material whose main component is two or more elements of 60
A method of manufacturing a halftone phase shift mask, which is characterized by comprising a film material having a thickness of 0 nm or less. 8. The method of manufacturing a halftone phase shift mask according to claim 3, wherein the high-transmittance film contains silicon as a main component, and oxygen, nitrogen, carbon, fluorine, or any of them is used. 2. A method of manufacturing a halftone type phase shift mask, comprising a material containing two or more kinds of elements. 9. The method of manufacturing a halftone phase shift mask according to claim 1, wherein the light semi-transmissive portion is a film whose material itself has both a function of controlling light transmittance and a phase shift function. A method of manufacturing a halftone type phase shift mask, which is characterized by being configured. 10. The method of manufacturing a halftone type phase shift mask according to claim 9, wherein the film having both the function of controlling the light transmittance of the light semi-transmissive portion and the phase shift function is tantalum, chromium,
Any one of molybdenum, silicon, tungsten, or two or more of these elements, oxygen, nitrogen, carbon, boron,
A method of manufacturing a halftone phase shift mask, comprising a material containing any one of fluorine or two or more of these elements.