JP3219619B2 - X-ray mask, manufacturing method of the mask, and device manufacturing method using the mask - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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 manufacture of various products by partially altering the surface of a workpiece using lithography technology is widely used in industry, particularly in the field of the electronics industry. A large number of products having the same pattern can be manufactured. The surface deterioration of the workpiece is performed by irradiation of various energy rays, and a mask in which a blocking material is partially disposed is used for pattern formation at this time. When the irradiation energy is visible light or ultraviolet light, a mask provided with a black opaque pattern such as silver or chrome on a transparent substrate such as glass or quartz is generally used as such a mask.

However, in recent years, as finer pattern formation is required and lithography processing is required in a shorter time, particle beams such as electron beams and ion beams, or X-rays, have attracted attention as irradiation energy rays. It has become

[0004] These energy rays cannot be passed through glass or quartz plates that have been used as mask substrate members for visible light or ultraviolet light, and are not suitable as mask substrate materials. In particular, in lithography using X-rays, various inorganic thin films, for example, ceramic thin films such as silicon, silicon nitride, and silicon carbide, or organic polymer thin films such as polyimide, polyamide, and polyester, and a laminated thin film of these materials are used. A mask is formed by forming a metal such as gold, platinum, or tungsten on the surface of the film as an energy ray absorber in a pattern. Since this mask usually has no self-preserving property, it needs to be held on 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 energy ray absorbing mask material pattern formed on one side is bonded to one end face of the annular holding substrate.
A line mask structure is configured.

In order to perform lithography using an X-ray mask structure as described above, a so-called tube X which is conventionally generated by applying an electron beam to a metal target such as palladium or rhodium as an X-ray source. Although a radiation source has been considered to be the mainstream, SOR lithography utilizing radiation emitted from a synchrotron ring has recently attracted attention.

[0006]

However, when employing SOR lithography, a problem which has not been considered before has emerged. That is, if the wavelength of the X-ray is 4
The change from {} to 10}, the increase in irradiation intensity by more than two orders of magnitude, and the increase in heat generated as a result thereof have required various countermeasures to cope with these problems. For example, from an organic film such as polyimide as an energy beam transmitting body, Si, S having excellent thermal conductivity and a small thermal expansion coefficient is used.
For inorganic films such as iN, SiC, etc., and the film thickness is from 8 μm to 2 μm.
m, and since the synchrotron irradiation light has parallelism, the transfer line width is expected to be from 0.8 μm to 0.2 μm or less. On the other hand, X-ray absorbers have also been required to respond, such as low thermal expansion, low stress materials, and process stability.

According to the present invention, in order to satisfy the above conditions, by selecting a material having high X-ray absorptivity as an X-ray absorber material and having a low coefficient of thermal expansion and excellent in dry etching, the aging and process stability can be improved. An object of the present invention is to provide an excellent mask for X-ray lithography.
It is another object of the present invention to provide a method for manufacturing the X-ray mask, a method for producing a micro device using the mask, and the like.

[0008]

For this purpose, we have developed SiN and Si suitable as Si and X-ray transmitting bodies.
A study was conducted to find an X-ray absorber pattern material having a coefficient of thermal expansion as close as possible to that of ceramics such as C, AlN, and C, and having a low stress and a good surface state. Alloys were found.

That is, in the X-ray mask of the present invention, the absorber pattern formed on the mask membrane is an alloy containing tungsten (W) and molybdenum (Mo).
The preferred orientation of the crystal of the -Mo alloy is {110}.

Here, it is preferable that the ratio of molybdenum contained in the whole alloy is 0.1 to 50% by weight.

The method of manufacturing an X-ray mask of the present invention is a method of manufacturing an X-ray mask, wherein the absorber pattern formed on the mask membrane is an alloy containing tungsten (W) and molybdenum (Mo). A step of forming an absorber pattern of the alloy by dry etching with a gas plasma mainly containing a carbon fluoride-based or sulfur fluoride-based gas.

Another embodiment of the method of manufacturing an X-ray mask according to the present invention is a method of manufacturing an X-ray mask in which an absorber pattern formed on a mask membrane is an alloy containing tungsten (W) and molybdenum (Mo). A step of forming an absorber pattern of the alloy by a sputter deposition method using an inert gas.

A device production method according to the present invention is characterized in that a device is produced by exposing and transferring a pattern on a substrate using the X-ray mask.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below. FIG. 1 is a cross-sectional view of an X-ray mask structure, wherein 1 is a holding frame, 2 is an X-ray support film as a membrane, 3 is an X-ray absorber pattern, and 4 is a frame. Note that it is preferable to further provide a protective film, a conductive film, an antireflection film for alignment light, and the like of the X-ray absorber.

A holding frame 1 for holding the X-ray support film 2
Is composed of single-crystal Si. A frame 4 as a reinforcing member is joined to the holding frame 1, and as a material of the frame 4, heat-resistant glass, Si ceramics, or the like is used. The X-ray supporting film 2 needs to have a sufficient transmittance for X-rays and a strength enough to be self-standing.
As a 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 thereof are used.
The thickness is in the range of 1 to 10 μm. Further, it is necessary that the X-ray absorber 3 absorbs X-rays sufficiently and has good workability. The material is an alloy of W (tungsten) and Mo (molybdenum), and the thickness is 0.1 to 1.0 μm.

Next, a method for producing the X-ray absorber 3 will be described. A sputter deposition apparatus was used as a film forming apparatus, and W and Mo were 99 to 90 wt%,
An alloy body of 10 wt% to 10 wt% is used. As for the composition ratio of the alloy, the amount of Mo can be used up to a maximum of about 50 wt%, but a condition for increasing the density is selected in consideration of the X-ray absorbing ability. The gas used is Ar
(Argon).

FIG. 2 is a graph showing a change in film stress with respect to gas pressure when a target containing only W is used in advance. Stress (compression) decreases linearly with gas pressure. Further, the graph of FIG. 3 shows a change when a W-Mo target is used. As can be seen from FIG.
The gas pressure changes extremely around 2 Pa, and the stress (compression) decreases. This means that a low stress X
This shows that a line absorber film can be formed. In general, it is known that when a film is formed in a low vacuum, the amount of gas taken up in the film increases and the stress decreases, but this is not preferable because it lowers the density and increases the change with time. From this, it is clear that this phenomenon of W-Mo is extremely effective in forming an X-ray absorber film and forming a mask structure. Depending on the composition ratio of W and Mo and the type of sputtering apparatus, the conditions of the gas pressure may shift slightly, but the presence of a variation point remains unchanged.

In FIG. 3, as a result of X-ray analysis analysis, the crystal orientation of the film formed at a higher vacuum than the mutation point was {211}, whereas at the mutation point and the low vacuum region The preferred orientation of the formed film was {110}. This means that the alloy film of W and Mo is formed under the conditions (sputter gas pressure).
Indicates that the crystal state can be changed, and a high-density, low-stress film with little incorporated gas can be obtained near the transition point. Therefore, as the X-ray absorber 3, it is preferable to use a film having a preferred orientation of {110}, and more preferably a film near the mutation point.

As described above, the point that our proposed mask is excellent is that a high-density X-ray absorbing film having a uniform composition and good surface properties can be formed with a low stress by a sputter deposition method. The reasons are as follows: (1) Since the properties of both metals are close, a uniform sputter target can be used. (2) Since the sputtering rates of both metals are equal, a uniform deposited 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 with respect to an etching gas such as SF6 and CF4. And the like.

Next, some more specific embodiments will be described.

<Example 1> For the purpose of producing a mask structure for X-ray lithography, X-rays were deposited on a 3-inch φ, 2 mm-thick silicon substrate serving as an X-ray holding frame by CVD.
A mask blank was formed by forming a 2 μm-thick SiN membrane film as a line support film. The SiN film on the back surface of the Si substrate was previously provided with a window for back etching having a size of 20 × 20 mm 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 deposition apparatus was used as a film forming apparatus for the X-ray absorber. 90wt each of W and Mo as targets
%, An alloy body containing 10% by weight. Ar gas was used as a sputtering gas. The gas pressure is 1.5 Pa and the RF power is 75 W. The film formation time was 0.9 μm for 80 minutes. The stress of this film was 2 × 10 ⁷ dyne / cm ² , a slight tensile stress.

Next, an absorber pattern was formed using the above structure. First, the chromium film was removed to a thickness of 0.1 mm using an EB evaporation apparatus.
05 μm, laminated on the W-Mo film. In addition, PMMA
A 0.5 μm layer of a system resist was laminated by spin coating. After a predetermined pre-bake process, the EB drawing apparatus is used to set the value of 0.
A 30 μm pattern was drawn. After a predetermined development process, a 0.30 μm resist pattern was formed. Subsequently, CF4 was used as an etching gas in a dry etching apparatus.
Using a resist pattern as a mask, 0.3 μm C
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 a W—Mo alloy.

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

Example 2 For the purpose of producing a mask structure for X-ray lithography, a 2 μm-thick SiC membrane film serving as an X-ray supporting film was formed on a silicon substrate having a diameter of 3 inches and a thickness of 2 mm by a CVD method. And a mask blank was prepared. Note that a window for back etching having a size of 20 × 20 mm was provided in advance on the SiC film on the back surface of the Si substrate using a mask. The stress of the membrane is 1 × 10 ⁹ dyne /
The value of the tensile stress in cm ² is shown. On the other hand, a sputter deposition apparatus was used as an apparatus for forming an X-ray absorber film. An alloy containing 95 wt% and 5 wt% of W and Mo, respectively, was used as a target. Ar was used as a sputtering gas. The gas pressure is 2 Pa and the RF power is 100 W. Film formation time is 6
It was 0.8 μm at 0 minutes. The stress of this film is -2 × 10
^The compressive stress was as small as ⁷ dyne / cm ² . Subsequent steps are the same as in the above embodiment. As a result, a very good mask structure for X-ray lithography could be obtained.

<Embodiment 3> In the above-described embodiment 1, W
As the gas used for etching of the -Mo absorber pattern, when using a mixed gas of varied CF4 and O ₂ as SF6, it was possible to obtain a mask having a very good etched pattern.

<Embodiment 4> Next, an embodiment of an X-ray exposure apparatus using the X-ray mask prepared as described above will be described. FIG. 4 is an overall view of the X-ray exposure apparatus. In the figure, a synchrotron radiation light 12 in the form of a sheet beam emitted from a light emitting point 11 of a synchrotron radiation source 10 is radiated by a convex mirror 13 having a slight curvature. It is enlarged in a direction perpendicular to the optical orbit plane. The expanded radiated light is adjusted by the moving shutter 14 so that the exposure amount becomes uniform within the irradiation area, and the radiated light that has passed through the shutter 14 is adjusted by the X-ray mask 15.
It is led to. The X-ray mask 15 is created by the method described in any of the embodiments described above.
The wafer 16 is obtained by applying a 1 μm-thick resist by a spin coat method and performing a pre-bake under predetermined conditions.
The X-ray mask 15 is arranged at a close distance of about 30 μm. After mask patterns are arranged and transferred on 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 5> Next, a method for producing a micro device using the X-ray mask and the X-ray exposure apparatus will be described. IC and LS
I and other semiconductor chips, liquid crystal devices, micromachines,
And a thin-film magnetic head. The following shows an example of a semiconductor device.

FIG. 5 shows an overall flow of semiconductor device production. In step 1 (circuit design), the circuit of the semiconductor device is designed. Step 2 is a process for making a mask on the basis of the circuit pattern design. on the other hand,
In step 3 (wafer manufacture), 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 prepared X-ray mask and wafer. The next step 5 (assembly) is called a post-process, and is a process of forming a semiconductor chip using the wafer produced in step 4, and includes processes such as an assembly process (dicing and bonding) and a packaging process (chip encapsulation). including. In step 6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device manufactured in step 5 are performed. Through these steps, a semiconductor device is completed and shipped (step 7).

FIG. 6 shows a detailed flow of the wafer process. Step 11 (oxidation) oxidizes the wafer's surface. Step 12 (CVD) forms an insulating film on the wafer surface. Step 13 (electrode formation) forms electrodes on the wafer by vapor deposition. Step 14 (ion implantation) implants ions into the wafer. Step 15
In (resist processing), a photosensitive agent is applied to the wafer. Step 16 (exposure) uses the above-described exposure apparatus to print and expose the circuit pattern of the mask onto the wafer. Step 17 (development) develops the exposed wafer. In this step, PEB (Post Expo
sure Bake) process. In step 18 (etching), portions other than the developed resist image are removed. In step 19 (resist stripping), unnecessary resist after etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer. By using the production method of this embodiment, it is possible to produce a highly integrated semiconductor device which has been difficult in the past.

[0030]

According to the present invention, a high-density X-ray absorber having a uniform composition and good surface properties can be formed with low stress by using an alloy containing W and Mo as an X-ray absorber. Thus, a highly accurate X-ray mask can be provided. By using this X-ray mask, it is possible to provide an exposure apparatus and a device production method capable of performing exposure transfer with high precision.

[Brief description of the drawings]

FIG. 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 formation condition of a W film.

FIG. 3 is a graph showing a change in stress depending on a film formation condition of W-Mo.

FIG. 4 is an overall configuration diagram of an embodiment of an X-ray exposure apparatus.

FIG. 5 is a diagram showing an overall flow of semiconductor device production.

FIG. 6 is a diagram showing a detailed flow of a wafer process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Support frame 2 X-ray support film 3 X-ray absorber pattern 4 Frame

Continuation of the front page (72) Inventor Keiko Chiba 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (56) References JP-A-56-112727 (JP, A) JP-A-63-155618 ( JP, A) JP-A-60-61750 (JP, A) JP-A-63-51632 (JP, A) JP-A-2-94421 (JP, A) JP-A-5-299326 (JP, A) Hei 5-326380 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01L 21/027 G03F 1/16

Claims (5)

(57) [Claims] An absorber pattern formed on a mask membrane is made of tungsten (W) and molybdenum (Mo).
An X-ray mask, wherein the preferred orientation of the crystal of the W-Mo alloy is {110}. 2. The X-ray mask according to claim 1, wherein a ratio of molybdenum contained in the alloy is 0.1 to 50 wt% with respect to the whole. 3. An absorber pattern formed on a mask membrane is made of tungsten (W) and molybdenum (Mo).
A method for producing an X-ray mask which is an alloy containing: a step of forming an absorber pattern of the alloy by dry etching with a gas plasma mainly composed of a carbon fluoride-based or sulfur fluoride-based gas. A method for manufacturing an X-ray mask, comprising: 4. An absorber pattern formed on a mask membrane is made of tungsten (W) and molybdenum (Mo).
A method of manufacturing an X-ray mask which is an alloy containing, comprising a step of forming an absorber pattern of the alloy by a sputter deposition method using an inert gas. 5. A device manufacturing method for producing a device by exposing and transferring a pattern on a substrate using the X-ray mask according to claim 1.