JPH08167556A - X-ray mask, manufacture thereof, and producing method for device using x-ray mask - Google Patents

Abstract

PURPOSE: To obtain high X-ray absorbing material with a small thermal expansion coefficient and an excellent dry-etching performance by a method wherein an amorphous metal layer is contained in an absorber pattern to be formed on a mask membrane. CONSTITUTION: A silicon substrate, which becomes an X-ray retaining frame 1, is connected to the frame 4, which is reinforcement material, formed by heat-proof glass and the like. On this silicon substrate, a SiN membrane film, which becomes an X-ray retaining film 2, is formed using a CVD method, and mask blanks are formed on the X-ray retaining film 2, an X-ray absorber pattern 3, containing an amorphous metal layer 5, is formed by performing a sputtering method using inert gas and nitrogen gas. As a result, a high density X-ray absorbing body, having high adhering property, a uniform composition and excellent surface properties, can be formed with a small low stress.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mask suitable for X-ray lithography and a device manufacturing method using the same.

[0002]

2. Description of the Related Art The production of various products by partially modifying the surface of a material to be processed by using a lithographic technique is widely used in industry, particularly in the field of electronic industry. According to this method, It is possible to manufacture a large number of products having the same pattern. The alteration of the surface of the material to be processed is performed by irradiation with various energy rays, and in order to form a pattern at this time, a mask in which a blocking material is partially arranged is used. As such a mask, when the irradiation energy is visible light or ultraviolet light, a mask having a black opaque pattern such as silver or chrome provided on a transparent substrate such as glass or quartz is generally used.

However, in recent years, as finer pattern formation is demanded and lithographic processing is required in a shorter time, particle beams such as electron beams and ion beams, or X-rays are attracting attention as irradiation energy beams. Has become.

These energy rays cannot pass through the energy rays by the glass or quartz plate which has been used as a mask substrate member for visible light or ultraviolet light, and is not suitable as a mask substrate material. Therefore, particularly in lithography using X-rays, various inorganic thin films, for example, ceramic thin films of silicon, silicon nitride, silicon carbide, etc., organic polymer thin films of polyimide, polyamide, polyester, etc. A mask is formed by using a metal such as gold, platinum, or tungsten in the form of an energy ray absorber in a pattern on the film surface, which is used as a ray transmissive body. Since this mask usually has no self-preserving property, it needs to be held by a holder, and an annular holding substrate is generally used as the holder. That is, the peripheral portion of the energy ray transmitting holding thin film having the pattern of the energy ray absorbing mask material formed on one surface is adhered to one end surface of the annular holding substrate to form X.
A line mask structure is constructed.

By the way, in order to perform lithography using the X-ray mask structure as described above, conventionally, a so-called tube X is produced by causing an electron beam to act on a metal target such as palladium or rhodium as an X-ray source. It has been considered that a radiation source is the mainstream, but in recent years, SOR lithography using synchrotron radiation generated from a synchrotron ring has attracted attention.

[0006]

However, when trying to adopt SOR lithography, a problem that has not been considered hitherto has emerged. That is, the X-ray wavelength is 4
Since the change from Å to 10 Å and the increase in irradiation intensity by more than two digits and the accompanying rise in heat, etc., various measures have been required to deal with these problems. For example, an organic film such as polyimide is used as an energy ray transmitter, and Si, S having excellent thermal conductivity and a small coefficient of thermal expansion is used.
For inorganic films such as iN and SiC, and film thickness from 8μm to 2μ
Since the synchrotron irradiation light has a parallelism of about m, the transfer line width is expected to be 0.8 μm to 0.2 μm or less. On the other hand, the X-ray absorber has also been required to be dealt with in the same manner, such as low thermal expansion, low stress material, and process stability.

In order to satisfy the above conditions, the present invention selects a material having a high X-ray absorbing property as an X-ray absorber material and having a low coefficient of thermal expansion and being excellent in dry etching processing. An object of the present invention is to provide an excellent mask for X-ray lithography.
Furthermore, it is an object of the present invention to provide a method for manufacturing the X-ray mask, a method for manufacturing a minute device using the mask, and the like.

[0008]

To this end, we have proposed Si and SiN, Si suitable as X-ray transmitters.
When an X-ray absorber pattern material having a coefficient of thermal expansion as close to that of C, AlN, C, etc. as possible was obtained, and the stress was low and the surface state was good, an amorphous metal layer was formed. An X-ray absorber pattern containing was found.

That is, the X-ray mask of the present invention is characterized in that the absorber pattern formed on the mask membrane contains an amorphous metal layer.

Here, it is preferable that the amorphous metal layer is a compound of tungsten (W) and a tungsten alloy and nitrogen (N ₂ ). Further, it is preferable that the amorphous metal layer is a compound of molybdenum (Mo) and a molybdenum alloy and nitrogen (N ₂ ). Further, it is preferable that an absorption layer made of an alloy of W, Mo, W-Mo and W, Mo is formed on the amorphous metal layer. Further, it is preferable to provide an amorphous metal layer, an absorption layer, and an amorphous metal layer in order from the mask membrane side.

The X-ray mask manufacturing method of the present invention is characterized in that the amorphous metal layer is formed by a sputter deposition method using an inert gas and a nitrogen gas.

The X-ray mask manufacturing method of the present invention is characterized in that the absorber is formed on the amorphous metal layer by a sputter deposition method using an inert gas.

The X-ray mask manufacturing method of the present invention is characterized in that the pattern is formed by dry etching with a gas plasma mainly containing a carbon fluoride type gas or a sulfur fluoride type gas.

The device production method of the present invention is characterized by producing a device by exposing and transferring a pattern onto a substrate using the above X-ray mask.

[0015]

The preferred embodiments of the present invention will be described below. FIG. 1 is a sectional view of an X-ray mask structure, in which 1 is a holding frame, 2 is an X-ray support film which is a membrane, 3 is an X-ray absorber, 5 is an X-ray support film 2 and an X-ray absorber 3. The amorphous metal layer provided between the X-ray absorber 3 and the amorphous metal layer 5 forms a mask pattern.
4 is a frame. It is preferable to further provide a protective film for the X-ray absorber, a conductive film, an antireflection film for alignment light, and the like.

A holding frame 1 for holding the X-ray supporting film 2.
Is composed of single crystal Si. A frame 4, which is a reinforcing member, is joined to the holding frame 1, and the material of the frame 4 is heat-resistant glass, Si ceramics, or the like. The X-ray supporting film 2 needs to have sufficient transmittance for X-rays and have a strength enough to stand by itself.
As the material, for example, Si, SiO ₂ , SiN, Si
Inorganic films such as C, SiCN, BN, and AlN, radiation resistant organic films such as polyimide, and composite films of these are used.
The thickness is within the range of 1 to 10 μm. Further, the X-ray absorber 3 is required to sufficiently absorb X-rays and have good workability. The material is an alloy of W (tungsten) and Mo (molybdenum), and the thickness is 0.1 to 1.0 μm. The amorphous metal layer 5 is a W-Mo-N amorphous alloy and has a thickness in the range of 0.05 to 0.5 μm.

Next, a method of forming an absorber pattern composed of the X-ray absorber 3 and the amorphous metal layer 5 will be described.
A sputtering vapor deposition apparatus is used as a film forming apparatus, and W and Mo are 99 to 90 wt% and 1 to 1 as sputter targets, respectively.
An alloy body of 0 wt% is used. As for the composition ratio of the alloy, a maximum amount of Mo of about 50 wt% can be used, but a condition for increasing the density is selected in consideration of the X-ray absorption ability. The gas used is Ar (argon).

FIG. 2 is a graph showing changes in film stress with respect to gas pressure when a target containing only W is used in advance. The stress (compression) decreases linearly with the gas pressure. The graph of FIG. 3 shows changes when W-No-N and W-Mo are continuously formed using a W-Mo target. As can be seen from FIG. 3, the gas pressure is 2
It changes extremely near Pa and the stress (compression) is reduced. This indicates that a low stress X-ray absorber film can be formed under high vacuum film forming conditions. It is generally known that when a film is formed in a low vacuum, the amount of gas taken in the film increases and the stress decreases, but this is not preferable because it lowers the density and increases the change over time. From this, it is clear that this phenomenon of W-Mo is extremely effective for forming an X-ray absorber film and for forming a mask structure. Although the gas pressure condition may shift to some extent depending on the composition ratio of W and Mo and the type of the sputtering apparatus, the fact that there is a mutation point remains unchanged.

In FIG. 3, the crystallographic state of the film formed in a vacuum higher than the mutation point was {211} as the preferential orientation as a result of X-ray analysis analysis, whereas in the mutation point and the low vacuum region. The preferential orientation of the formed film was {110}. This means that the alloy film of W and Mo was formed under the conditions (sputtering gas pressure).
It is shown that the crystal state can be changed by, and that a high-density, low-stress film with little gas uptake can be obtained near the mutation point. Therefore, as the X-ray absorber 3, it is preferable to use a film having a preferential orientation of {110} and further a film near the mutation point.

As described above, the advantage of the mask proposed by us is that a high-density X-ray absorbing film having a uniform composition and good surface properties can be formed with low stress by the sputter deposition method. The reasons are as follows: (1) Since both metals have similar properties, a homogeneous sputter target can be used. (2) Since the sputter rates of both metals are the same, a uniform vapor deposition film can be obtained. (3) A low-stress sputtered film can be formed in a high vacuum region (high density). (4) It has a uniform etching characteristic for etching gases such as SF6 and CF4. And so on.

Next, some more specific examples will be described.

<Example 1> For the purpose of forming a mask structure for X-ray lithography, an X-ray holding frame was formed on a silicon substrate of 3 inches φ and a thickness of 2 mm by a CVD method.
A mask blank was prepared by depositing a SiN membrane film as a line supporting film to a thickness of 2 μm. A back etching window having a size of 20 × 20 mm was previously provided in the SiN film on the back surface of the Si substrate by using a mask. The stress of the membrane film showed a tensile stress value of 4 × 10 ⁸ dyne / cm ² . On the other hand, a sputter vapor deposition apparatus was used as a film forming apparatus for the X-ray absorber including the amorphous metal layer. As the target, an alloy body containing 90 wt% and 10 wt% of W and Mo was used. Ar and N ₂ gas were used as the sputtering gas. In order to form the amorphous layer 5, the ratio of Ar and N ₂ gas was set to 1: 1. The sputtering gas pressure is 4 Pa and the RF power is 75 W. The film formation time was 10 minutes and 0.1 μm. Furthermore, sputter is performed only with Ar gas continuously,
The X-ray absorption layer 3 was formed. Film formation time is 60 minutes and 0.8μ
It was m. The stress of the film thus formed is −3 × 10 ⁷
It was a slight tensile stress of dyne / cm ² .

Next, an absorber pattern was formed using the above structure. First, using an EB vapor deposition device, a Cr film was deposited on the surface of the film.
It was laminated on the W-Mo film with a thickness of 05 μm. Furthermore, PMMA
The system resist was laminated by 0.5 μm by spin coating. After a predetermined pre-baking process, an EB drawing device was used to obtain 0.
A 30 μm pattern was drawn. A 0.30 μm resist pattern was formed through a predetermined development process. Then, CF4 is used as an etching gas in the dry etching apparatus.
By using a resist pattern as a mask and a C of 0.3 μm.
An r pattern was formed. Subsequently, after removing the resist with O ₂ gas plasma, etching was performed with SF 6 gas plasma to form a 0.30 μm absorber pattern of the W—Mo alloy.

Next, back etching of the back surface of the Si substrate was performed. Etching was performed by applying a 30 wt% KOH solution at 110 ° C. to the window portion of the SiN film which was previously provided. The absorber pattern on the surface was completely shielded so that the etching solution would not act. It took about 6 hours to etch a 2 mm pressure Si substrate. Finally, a doughnut-shaped reinforcing body having a diameter of 3 inches and a thickness of 8 mm was bonded to the frame 4 by using an epoxy adhesive, whereby an extremely good mask structure for X-ray lithography could be obtained.

<Embodiment 2> FIG. 4 is a cross-sectional view of another embodiment of the X-ray mask structure. For the purpose of creating a mask structure for X-ray lithography, SiC that becomes an X-ray supporting film by a CVD method on a silicon substrate with a diameter of 3 inches and a thickness of 2 mm.
A membrane blank having a thickness of 2 μm was formed to prepare a mask blank. A back etching window having a size of 20 × 20 mm was previously provided in the SiC film on the back surface of the Si substrate by using a mask. The stress of the membrane is 1 × 10 ⁹ dy
The value of the tensile stress of ne / cm ² is shown. On the other hand, a sputter vapor deposition apparatus was used as a film forming apparatus for the X-ray absorber layer film including the amorphous metal layer. W and Mo are 9 targets respectively
An alloy body containing 5 wt% and 5 wt% was used. As the sputtering gas, Ar: N ₂ gas of 2: 1 was used for forming the amorphous layer 5. The gas pressure is 2 Pa and the RF power is 100 W. The film formation time was 8 minutes and 0.1 μm. Further, the X-ray absorber layer 3 was formed on the amorphous metal layer 5 by continuously performing film formation with Ar gas alone for 60 minutes at the same power. Amorphous layer 6 is similarly formed on the upper layer in succession.
About 0.1 μm. The stress of the film thus formed was a slight compressive stress of −2 × 10 ⁷ dyne / cm ² . The subsequent steps are the same as those in the above embodiment. As a result, a very good mask structure for X-ray lithography could be obtained.

<Third Embodiment> In the above first embodiment, W
As a gas used for etching the pattern of the absorbing layer composed of the amorphous layer of -Mo-N and the W-Mo alloy layer, S
When a mixed gas of CF4 and O ₂ was used instead of F6,
A mask having an extremely good etching pattern could be obtained.

<Example 4> In Example 1, W-Mo
Instead of (90:10 wt%), W-Mo (95: 5 wt%)
%) Alloy was used. Under the same conditions, an amorphous alloy of W-Mo-N was provided in the lower layer film in a thickness of 0.1 μm, and an M-Mo alloy was continuously laminated thereon in a thickness of 0.8 μm. Thereafter, an extremely good mask having a line width pattern of 0.3 μm could be obtained through the same processes and steps as described above.

<Example 5> In Example 4, an amorphous alloy, that is, a W-Mo-N film alone was formed to a thickness of 0.9 [mu] m. -8 × 10 ⁷ under film forming conditions with a sputtering gas pressure of 4 Pa
The compressive stress value was dyne / cm ² . According to this example, compared with the conventional WN film, the film formation under the same conditions had a low stress and a good surface property. Furthermore, since the amount of nitrogen could be limited, a relatively high density absorber pattern was obtained.

<Embodiment 6> Next, an embodiment of an X-ray exposure apparatus using the X-ray mask prepared as described above will be described. FIG. 5 is an overall view of the X-ray exposure apparatus. In the figure, a sheet-beam-shaped synchrotron radiation 12 emitted from a light emitting point 11 of a synchrotron radiation source 10 is emitted by a convex mirror 13 having a slight curvature. It is enlarged in the direction perpendicular to the optical orbital plane. The expanded radiant light is adjusted by the moving shutter 14 so that the exposure amount is uniform in the irradiation area, and the radiated light that has passed through the shutter 14 is X-ray mask 15.
Be led to. The X-ray mask 15 is produced by the method described in any of the embodiments described above.
The wafer 16 was obtained by applying a resist having a thickness of 1 μm by a spin coating method and prebaking it under predetermined conditions.
The X-ray mask 15 and the X-ray mask 15 are arranged at an interval of approximately 30 μm. After the mask patterns are aligned and exposed and transferred to a plurality of shot areas of the wafer 16 by stepping exposure, the wafer is collected and developed. As a result, a negative resist pattern having a line width of 30 μm and a height of 1 μm was obtained.

<Embodiment 7> Next, a method for producing a minute device using the X-ray mask and the X-ray exposure apparatus will be described. Microdevices referred to here include ICs and LSs.
Semiconductor chips such as I, liquid crystal devices, micromachines,
Examples thereof include a thin film magnetic head. The following shows an example of a semiconductor device.

FIG. 6 shows an overall flow of manufacturing a semiconductor device. In step 1 (circuit design), a semiconductor device circuit is designed. In step 2 (mask manufacturing), a mask having the designed circuit pattern is manufactured. on the other hand,
In step 3 (wafer manufacturing), a wafer is manufactured using a material such as silicon. Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the X-ray mask and the wafer prepared above. The next step 5 (assembly) is called a post-process, and is a process of forming a semiconductor chip by using the wafer manufactured in step 4, such as an assembly process (dicing, bonding), a packaging process (chip encapsulation), and the like. including. In step 6 (inspection), the semiconductor device manufactured in step 5 undergoes inspections such as an operation confirmation test and a durability test. Through these steps, the semiconductor device is completed and shipped (step 7).

FIG. 7 shows a detailed flow of the wafer process. In step 11 (oxidation), the surface of the wafer is oxidized. In step 12 (CVD), an insulating film is formed on the wafer surface. In step 13 (electrode formation), electrodes are formed on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted in the wafer. Step 15
In (resist processing), a photosensitive agent is applied to the wafer. In step 16 (exposure), the circuit pattern of the mask is printed and exposed on the wafer by the exposure apparatus described above. In step 17 (development), the exposed wafer is developed. In this process, PEB (Post Expo
sure Bake) process is included. In step 18 (etching), parts other than the developed resist image are removed. In step 19 (resist stripping), the resist that is no longer needed after etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer. By using the manufacturing method of the present embodiment, it is possible to manufacture a highly integrated semiconductor device which has been difficult to manufacture in the past.

[0033]

As described above, according to the present invention, by forming an X-ray absorber layer including an amorphous alloy layer, a high-density X-ray absorber having a high adhesiveness and a uniform composition and a good surface property can be obtained with a low stress. A highly accurate X-ray mask that can be formed can be provided. By using this X-ray mask, it is possible to provide an exposure apparatus and a device production method capable of highly accurate exposure transfer.

[Brief description of drawings]

1 is a cross-sectional view of an embodiment of an X-ray mask structure.

FIG. 2 is a graph showing a change in stress depending on a film forming condition of a W film.

FIG. 3 is a graph showing changes in stress depending on W-Mo film forming conditions.

FIG. 4 is a cross-sectional view of another embodiment of an X-ray mask structure.

FIG. 5 is an overall configuration diagram of an embodiment of an X-ray exposure apparatus.

FIG. 6 is a diagram showing an overall flow of semiconductor device production.

FIG. 7 is a diagram showing a detailed flow of a wafer process.

[Explanation of symbols]

 1 Support frame 2 X-ray support film 3 X-ray absorber pattern 4 frame

Front page continuation (72) Inventor Keiko Chiba 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (9)

[Claims] 1. An X-ray mask, wherein the absorber pattern formed on the mask membrane includes an amorphous metal layer. 2. The X-ray mask according to claim 1, wherein the amorphous metal layer is a compound of tungsten (W) and a tungsten alloy and nitrogen (N ₂ ). 3. The X-ray mask according to claim 1, wherein the amorphous metal layer is a compound of molybdenum (Mo) and a molybdenum alloy and nitrogen (N ₂ ). 4. W, M on the amorphous metal layer
The X-ray mask according to claim 1, wherein an absorption layer made of an alloy of o, W-Mo and W, Mo is formed. 5. The X-ray mask according to claim 1, wherein an amorphous metal layer, an absorption layer, and an amorphous metal layer are provided in this order from the mask membrane side. 6. The method of manufacturing an X-ray mask according to claim 1, wherein the amorphous metal layer is formed by a sputter deposition method using an inert gas and nitrogen gas. Method for manufacturing X-ray mask. 7. The method of manufacturing an X-ray mask according to claim 1, wherein the absorber is formed on the amorphous metal layer by a sputter deposition method using an inert gas. A method for manufacturing an X-ray mask, comprising: 8. The method for manufacturing an X-ray mask according to claim 1, wherein the pattern is formed by dry etching with a gas plasma mainly containing a carbon fluoride-based gas or a sulfur fluoride-based gas. A method of manufacturing an X-ray mask, comprising: 9. A device production method, wherein a device is produced by exposing and transferring a pattern onto a substrate using the X-ray mask according to claim 1. Description: