JP3391699B2 - X-ray mask manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray mask in which tantalum is used as a material for a mask pattern which blocks X-rays, and a manufacturing method thereof.

[0002]

2. Description of the Related Art To further increase the degree of integration of LSI,
The key is the lithography technology for forming fine patterns. Therefore, a lithography technique using X-rays (synchrotron radiation) has been developed. In this X-ray lithography technique, an X-ray mask on which a pattern that blocks X-rays is formed and arranged is used. This X-ray mask is
On a substrate (membrane) made of SiN or SiC,
A light shielding pattern made of tantalum (Ta) or the like is formed.

FIG. 11 is a configuration diagram showing a configuration of an X-ray mask which has been conventionally used. As shown in FIG.
The X-ray mask 1101 has a structure in which a membrane 1102 is formed on a frame 1103 and a mask pattern 1104 is formed on the membrane 1102. Here, the membrane 1102 normally has a thickness of 2
It is composed of a SiN film or a SiC film of μm.
Further, the frame 1103 normally has a thickness of 1 to 2 mm.
It is composed of a silicon substrate. This silicon substrate is selectively etched with, for example, an aqueous potassium hydroxide solution, and a rectangular or circular window is formed in the center thereof to be used as a frame. Also, the mask pattern 1104
Is made of a material that absorbs X-rays, for example, Ta.

Here, a method of manufacturing the X-ray mask will be briefly described. First, as shown in FIG. 12A, a silicon nitride film 1202 is formed on the front surface and the back surface of a silicon wafer 1201 by a low pressure chemical vapor deposition method. Next, as shown in FIG. 12B, the Ta film 120 is formed on the silicon nitride film 1202 on the main surface side by RF sputtering.
3 is formed. Next, as shown in FIG.
An oxide film pattern 1204 made of silicon oxide is formed on the film 1203. The oxide film pattern 1204 may be formed, for example, as shown below. First, a thin film made of silicon oxide is formed, and a resist pattern is formed thereon by a known electron beam lithography technique. Then, using the resist pattern as a mask, the thin film made of silicon oxide is selectively removed by reactive ion etching or the like, and then the resist pattern may be removed.

Next, this time, the Ta film 1203 is selectively removed by etching using the oxide film pattern 1204 made of silicon oxide as a mask, and then the oxide film pattern 12 is removed.
04 is removed. As a result, as shown in FIG. 12D, the membrane 1102 made of silicon nitride on the main surface side.
A state in which the mask pattern 1104 is formed on the top is obtained. Next, the central portion of the silicon nitride film 1202 on the back surface side is removed. The area to be removed is the exposure area of the X-ray mask to be formed. Then, by using the silicon nitride film 1202 on the back surface from which the central portion has been removed as a mask, the silicon wafer 1201 is selectively etched and removed using an aqueous potassium hydroxide solution, so that the frame 110 shown in FIG.
3 is formed.

[0006]

By the way, since the absorber of the X-ray mask is patterned on the membrane made of a silicon nitride thin film or a silicon carbide thin film, it is necessary to control the residual stress of the absorber thin film to be small. Is. In the conventional RF sputtering method, as shown in Reference 1, the stress of the Ta thin film is controlled by adjusting the gas pressure during sputtering with high accuracy (Reference 1: T. Yoshih.
ara and K. Suzuki, "Sputtering of fibrous-structured
low-stess Ta films for x-ray masuks "J.Vac.Sci.Te
chnol.B12 (1994) pp4001 to 4004).

However, it is known that in the Ta thin film formed by the conventional RF sputtering method, the residual stress of the formed Ta thin film changes greatly toward the compression side at the same time when the Ta thin film is taken out from the vacuum exhaust to the atmosphere after the film formation. ing. According to Document 2, the following is reported. First, the Ta thin film formed by the RF sputtering method has a stress change of 20 MPa or more on the compression side in the first 30 hours after being taken out into the atmosphere. The change in stress after that should be small. And
It has been reported that the stress changes due to the diffusion of oxygen through the grain boundaries (Reference 2: T. Yoshihara).
"Variation of internal stress in Ta films" J.Vac.S
ci.Technol.B11 (1993) pp301-303).

Further, even when the Ta thin film is formed into a pattern even when it is taken out into the atmosphere and the stress is saturated, the position of the formed pattern deviates from the designed value. That is, a new surface exposed to the atmosphere is formed by the pattern formation, and as a result, the stress of the formed pattern changes and the pattern is displaced. For example, as shown in FIG.
When arranging a pattern of a predetermined size at a predetermined interval,
After the etching for forming the pattern, the pattern is deviated as shown by the arrow in FIG.

That is, first, as shown in FIG. 13A, the pattern is divided into nine regions and patterns are formed in the respective regions with respective dimensions. For example, in the upper left area, a stripe pattern with a size of 0.3 μm is added to
Form at m intervals. Similarly, for example, in the central region, a stripe pattern with a dimension of 0.2 μm is set to 0,
Formed at 2 μm intervals. Then, after the Ta patterns were formed on the membrane, the state of positional deviation of the patterns was measured before and after forming the frame in which the membrane is arranged.

Before forming the frame, FIG.
Since the membrane 1102 is formed on the thick silicon wafer 1201 as shown in FIG. 11, even if stress is generated in the formed mask pattern 1104, they do not cause much positional displacement. However, as shown in FIG. 11, when the frame 1103 is formed, the exposure area of the membrane 1102 exists independently.
If a stress is generated in the mask pattern 1104 formed on the mask pattern 1104, the mask pattern 1104 tries to release the stress, so that the formation position of the mask pattern 1104 is displaced.

In this way, after forming the frame,
As shown in FIG. 13B, the larger the positional deviation is, the larger the area where the stripe pattern having the smaller width and the smaller interval is formed. In FIG. 13B, the direction in which the pattern is displaced and the amount of displacement are indicated by the direction of the arrow and its length. As described above, Ta formed by the conventional RF sputtering method
When a thin film is used, a very large positional deviation occurs, especially in the case of a fine pattern, and it is difficult to form an X-ray mask with high positional accuracy.

The present invention has been made in order to solve the above problems, and an object thereof is to suppress the displacement of the mask pattern in an X-ray mask using a tantalum film as the mask pattern. .

[0013]

Means for Solving the Problems The method of <br/> manufacturing X-ray mask of the present invention, first, a plasma flow of xenon gas by electron cyclotron resonance in the vacuum vessel is evacuated to a predetermined degree of vacuum A plasma generating means for generating and a target made of tantalum are prepared, a membrane is placed facing the plasma generating means in the direction of the plasma flow of the plasma generating means, and a plasma is placed between the plasma generating means and the membrane. The target is placed so as not to obstruct the flow. And, the temperature of the membrane is 170 ℃ or more.
Then, a plasma flow is generated by the plasma generation means so that the membrane is exposed to this plasma flow, ions in the plasma are accelerated to collide with a target and sputter out tantalum atoms, and the tantalum atoms are ejected. Was deposited on the surface of the membrane exposed to the plasma flow to form a thin film of polycrystal of α-phase tantalum on the surface of the membrane, and the thin film was processed to form a mask pattern. As a result, the mask pattern is made of tantalum in a state where oxygen is prevented from entering the crystal grain boundaries. Then, in the method for manufacturing an X-ray mask of the present invention, first, a plasma generating means for generating a plasma flow of xenon gas by electron cyclotron resonance and a target made of tantalum are provided in a vacuum container evacuated to a predetermined vacuum degree. The membrane is prepared, the membrane is placed facing the plasma generating means in the direction in which the plasma flow of the plasma generating means flows, and the target is arranged between the plasma generating means and the membrane so as not to obstruct the plasma flow. And first, the membrane temperature
The temperature is set to 170 ° C. or higher, and a plasma flow is generated by the plasma generation means so that the membrane is exposed to this plasma flow, ions in the plasma are accelerated to collide with a target and sputter to eject tantalum atoms. Then, the tantalum atoms are deposited on the surface of the membrane exposed to the plasma flow to form a first thin film made of a polycrystal of α-phase tantalum on the surface of the membrane. Here, the deposition of tantalum atoms is once stopped for a predetermined time. Then, next, a plasma flow is continuously generated by the plasma generation means to bring the membrane into a state of being exposed to this plasma flow, ions in the plasma are accelerated to collide with a target and sputter to eject tantalum atoms, By depositing the tantalum atoms on the surface of the first thin film exposed to the plasma flow, a second thin film made of a polycrystal of α-phase tantalum is formed on the surface of the first thin film. The mask pattern is formed by processing the first thin film and the second thin film. Therefore, the upper part of the mask pattern is composed of the tantalum portion having a more stable crystal state, and the upper part of the mask pattern is more in a state in which oxygen is suppressed from entering the crystal grain boundaries more than the lower part of the mask pattern. Has become.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First Embodiment First, a first embodiment of the present invention will be described. In the first embodiment, as shown in FIG. 1, an X-ray mask 101 has a membrane 102 formed on a frame 103, and a tantalum () formed on the membrane 102 by an electron cyclotron resonance (ECR) sputtering method. The mask pattern 104 made of a Ta) film is formed. That is, a Ta film is formed by sputtering using plasma generated by using electron cyclotron resonance, and the Ta film is processed to form a mask pattern of an X-ray mask.

The method of manufacturing the X-ray mask will be briefly described below. First, as shown in FIG.
A silicon nitride film 202 is formed on the front surface and the back surface of the silicon wafer 201 by a low pressure chemical vapor deposition method. Next, in the first embodiment, as shown in FIG. 2B, a Ta film 203 having a thickness of about 400 nm is formed on the silicon nitride film 202 on the main surface side by the ECR sputtering method. Next, as shown in FIG. 2C, an oxide film pattern 204 made of silicon oxide is formed on the Ta film 203.

The oxide film pattern 204 may be formed, for example, as follows. First, a thin film made of silicon oxide is formed, and a resist pattern is formed thereon by a known electron beam lithography technique. Then, using the resist pattern as a mask, the thin film made of silicon oxide is selectively removed by reactive ion etching or the like, and then the resist pattern may be removed.

Next, the Ta film 203 is selectively removed by etching using the oxide film pattern 204 made of silicon oxide as a mask. This etching, for example,
The ECR ion flow etching method may be used. Then, after this, the oxide film pattern 204 is removed. As a result, as shown in FIG. 2D, the mask pattern 104 is formed on the membrane 102 made of the silicon nitride film on the main surface side.
A state in which is formed is obtained. Next, the central portion of the silicon nitride film 202 on the back surface side is removed. The area to be removed is the exposure area of the X-ray mask to be formed. Then, with the silicon nitride film 202 on the back surface side, from which the central portion has been removed, as a mask, an aqueous solution of potassium hydroxide is used to form the silicon wafer 2
By selectively etching away 01, the frame 103 shown in FIG. 1 is formed.

Next, in the first embodiment, ECR
A sputtering apparatus for forming a Ta film by the sputtering method will be described. This sputtering device, as shown in FIG.
First, a branch coupling type ECR plasma source 301 is provided. The ECR plasma source 301 includes a plasma chamber 311
ECR in a predetermined area in the plasma chamber 311
Magnetic coil 312 for forming a magnetic field satisfying the conditions
Is equipped with. Further, the plasma chamber 311 is provided with a microwave introduction window 313 made of a dielectric material such as quartz.

The plasma chamber 311 is the sputtering chamber 32.
In the sputtering chamber 320, a cylindrical Ta target 314 is arranged on the plasma emission side of the plasma chamber 311, and a shutter 321 that can be opened and closed is arranged outside the Ta target 314. The Ta target 314
Does not have to be cylindrical, and may be a polygonal cylinder, or may have a shape in which the diameter decreases in one direction. A negative DC voltage can be applied to the Ta target 314 by a DC power supply 315. In addition, the Ta target 314,
High frequency power may be applied.

A SiC stage 323 having a heater 322 on the back surface is arranged outside the shutter 321, and a substrate 324 to be processed is placed on the stage 323.
Is fixedly placed. A minute gap (about 0.3 mm) is provided between the substrate 324 and the stage 323 in order to avoid temperature unevenness of the substrate 324 due to partial contact of the substrate 324 with the stage 323. The substrate 324 is heated by infrared rays emitted from the heater 322 such as SiC. Here, the surface of the stage 323 is arranged not obliquely to the center line from the plasma chamber 311 but obliquely. Further, the stage 323 is rotatable about a normal line passing through its center.

A load lock chamber 331 communicates with the sputtering chamber 320 via a partition wall 332 that can be opened and closed. The plasma chamber 311 and the sputtering chamber 320 are
A vacuum container that is vacuum-exhausted by a vacuum exhaust unit (not shown) via an exhaust pipe 325 that communicates with the sputtering chamber 320 is configured. The same applies to the load lock chamber 331, and constitutes a vacuum container that is evacuated by vacuum evacuation means (not shown) through the communicating exhaust pipe 333.

Then, while evacuating, the gas introducing pipe 3
16, a xenon (Xe) gas is introduced into the plasma chamber 311 at a predetermined flow rate, and the inside of the plasma chamber 311 is set to a vacuum degree of, for example, about 3 × 10 ⁻⁴ Torr by the magnetic coil 312. A magnetic field satisfying the ECR condition is formed in an appropriate area. In this state, microwaves are introduced from the microwave source 302 having a frequency of 2.45 GHz into the plasma chamber 311 through the three-dimensional circuit 303 and the microwave introduction window 313 to generate a plasma of Xe gas in the plasma chamber 311. To generate.

Then, due to the divergent magnetic field formed by the magnetic field coil 312, the generated plasma becomes a plasma flow and flows toward the stage 323. By applying a negative DC voltage to the Ta target 314 by the DC power supply 315 in the state where the plasma flow is generated as described above, the ions near the Ta target 314 in the plasma flow are attracted to the Ta target 314. . The Ta target 314 is sputtered by the attracted ions.

Here, the Ta film is formed on the substrate 324 as follows. First, the temperature of the substrate 324 is set to about 170 ° C. by the heater 322. Then, the shutter 321 is opened in a state where a plasma flow is generated and no voltage is applied to the Ta target 314. As a result, the surface of the substrate 324 is irradiated with the plasma flow, and the substrate 32
4 Plasma clean the surface. Next, with the shutter 321 closed, the DC power supply 315 applies a negative DC voltage to the Ta target 314. As a result, the surface of the Ta target 314 is irradiated with ions in the plasma flow, and the surface of the Ta target 314 is sputter cleaned.

Then, the shutter 321 is released while the negative DC voltage is applied to the Ta target 314 by the DC power supply 315. As a result, some of the Ta atoms sputtered together with the plasma flow are introduced toward the substrate 324, and Ta atoms are deposited on the surface of the substrate 324 to form a Ta film. At this time, on the surface of the substrate 324,
At the same time, the plasma stream is being irradiated. The irradiated plasma flow is a substance formed by the divergent magnetic field of the magnetic field coil 312, and the energy of ions in the plasma flow is assumed to be 20 to 30 eV.
Therefore, the substrate 324 is irradiated by the irradiation of this plasma flow.
No spattering phenomenon occurs on the surface.

Since the ECR sputtering method can form a film at a low gas pressure of the order of 10 ^-4 Torr, it is possible to form a high-purity thin film with less residual gas taken into the film. Further, as described above, since low-energy ion irradiation of about 20 eV is performed during film formation, there is a feature that a dense and highly crystalline thin film with few impurities at crystal grain boundaries can be formed. As a result, according to the ECR sputtering method, the formed Ta film is assumed to be in a high quality state. FIG. 4 is a characteristic diagram showing a result of measuring a change in stress after the Ta film is taken out into the atmosphere. As is clear from FIG. 4, the Ta film produced according to the first embodiment has a small stress change of 10 MPa or less even after 1000 hours or more.

Here, when the state of the Ta film was observed with a transmission electron microscope (TEM), as shown in the TEM photograph of FIG. 5 (a), Ta formed of very large crystal grains of about 0.5 μm was used. It turned out to be configured. In addition,
In FIG. 5B, only the crystal grain boundaries are schematically shown. Moreover, as a result of the analysis by X-ray diffraction, it was found that the crystal was in the α phase which is a body-centered cubic lattice. As described above, the Ta film according to the first embodiment has very few crystal grain boundaries, is dense and has high quality so that the atoms of the adjacent crystal grains are continuously arranged, and has few impurities. Has become. As a result, it is considered that this Ta thin film is very excellent in stress stability even when it is exposed to the atmosphere, because the diffusion of oxygen in the Ta film through the crystal grain boundaries is very small.

Conventionally, it was considered necessary to amorphize (that is, eliminate grain boundaries) in order to ensure stress stability. It has been proposed to use a Ta ₄ B thin film as an absorber as this amorphous thin film having no crystal grain boundary, but it is difficult to etch and has not been put to practical use. However, it is possible to obtain an absorber film having excellent stress stability by making the crystal grains large enough to reduce the crystal grain boundaries and to make the crystal grain boundaries dense and high quality. Form 1
Ta film is shown.

As described above, since the absorber of the X-ray mask is patterned on the silicon nitride thin film or the silicon carbide thin film, it is necessary to control the residual stress to be small. The allowable value of residual stress depends on the pattern width to be formed and the membrane material, but at present,
Approximately 10 MPa or less is required. Then, according to the first embodiment described above, the residual stress of the formed Ta thin film is 10 MPa or less, which is within the allowable range. However, the stress of the Ta thin film formed on the membrane to form the absorber should be as small as possible. Here, a method for controlling the residual stress in the Ta film formed by the ECR sputtering method will be described below.

First, as shown in FIG. 6, the residual stress of the Ta film formed at a substrate temperature of about 170 ° C. at the start of film formation is close to 0, and when it becomes higher than that, the residual stress changes to the tensile side. . The results are obtained when Xe was used as the sputtering gas. When argon is used as the sputtering gas, a large residual stress of -1500 MPa is generated in the Ta film even when the substrate temperature at the start of film formation is 200 ° C or higher. Then, in the above-mentioned ECR sputtering method, xenon is used as a sputtering gas, and the temperature of the substrate at the time of starting film formation is set to 170 ° C. or higher to form a Ta film formed.
The film is in the α phase and has large crystal grains. On the other hand, when the Ta film is heat-treated after the film formation, as shown in FIG.
The stress of the Ta film changes to the compression side with the heat treatment time. In addition, FIG. 7 shows a vacuum degree of 5 × 10 ⁻⁴ Torr or less,
This is the result when heat treatment was performed at 300 ° C. by infrared heating.

Therefore, from the above two results, at the time of film formation, the residual temperature of the Ta film immediately after film formation is adjusted by adjusting the substrate temperature at the start of film formation to about 170 ° C. or more and adjusting the gas flow rate. Is a tensile stress. And
By performing heat treatment for a predetermined time after film formation, the stress of the Ta film formed on the membrane can be made almost zero. The heat treatment after film formation is not always necessary,
The stress of the Ta film can be made almost zero by adjusting and setting the substrate temperature at the start of film formation more strictly.

By the way, conventionally, there is a problem that the formed mask pattern is displaced due to stress not only at the time of film formation but also at the time of processing the Ta film into a mask pattern. However, Ta according to the first embodiment
According to the film, the pattern shift can be suppressed as described below. As shown in FIG. 13A, when the patterns having a predetermined size were arranged at predetermined intervals, how the patterns were displaced after etching for pattern formation was measured. Also in this case, as shown in FIG. 13A, the stripe pattern was divided into nine regions and a stripe pattern of 0.3 μm to 0.08 μm was formed in each region.

For example, in the upper left region, stripe patterns having a size of 0.3 μm are formed at intervals of 0.3 μm. Similarly, for example, in the central region, 0.2
Stripe patterns having a size of μm were formed at intervals of 0.2 μm. Then, after the Ta patterns were formed on the membrane, the state of positional deviation of the patterns was measured before and after forming the frame in which the membrane is arranged. However, here, the formed Ta pattern was formed by processing the Ta film according to the first embodiment.

As a result, as shown in FIG. 8, it can be seen that the positional deviation of the pattern is extremely small. 0.
In the region where the pattern of 08 μm is formed, the positional deviation of the pattern is reduced to 1/5 or less. in this way,
According to the Ta film in the first embodiment, the X-ray mask can be formed with higher accuracy than ever before.

Second Embodiment Next, a second embodiment of the present invention will be described.
In the second embodiment, the formation of the Ta film is divided into two stages. In the above-described first embodiment, as shown in FIG. 9, first, the substrate is heated to a predetermined temperature in step 901, then the substrate surface is plasma cleaned in step 902, and the target is sputter cleaned in step 903. Then, in step 904, the Ta film was formed.

On the other hand, in the second embodiment, the flow is shown in FIG. That is, first, in step 1001, the substrate is heated to a predetermined temperature, and then in step 10
In 02, the substrate surface is plasma cleaned, in step 1003, the target is sputter cleaned, and in step 1004, a Ta film is formed for the first time. In the second embodiment, the film formation is stopped when the Ta film is formed to a film thickness of about 20 to 30 nm in the first film formation. Then, in step 1005, the film formation stop state is continued for a predetermined time. Then step 100
At 6, the substrate surface is again plasma cleaned, then at step 1007 the target is sputter cleaned, and at step 1008, a second Ta film is formed.

As described above, since the Ta film is formed in a vacuum exhaust state, the substrate is heated by the infrared rays emitted from the heater. Therefore, T
In the initial substrate in which the a film is not formed at all, since the substrate is made of silicon, it is in a state of not absorbing infrared rays so much. In this state, the heater is set so that the substrate temperature is 170 ° C., for example. on the other hand,
If a Ta film is formed, T that absorbs infrared rays better on the substrate
Since the a film is formed, the temperature of the substrate increases. That is, in the above-described first embodiment, the Ta film is formed while the substrate temperature is gradually increasing.

On the other hand, in the second embodiment, as shown in FIG.
As shown in the flow of No. 0, 20 to 3 are formed in the first film formation.
After forming a Ta film having a very small thickness of about 0 nm, the film formation is temporarily stopped in step 1005. Therefore, according to the second embodiment, the temperature is stabilized at the state where the Ta film is formed on the substrate during the temporary stop of step 1005. Therefore, 2 in step 1008
When the Ta film is formed for the second time, the film is formed in a stable state without changing the substrate temperature. As a result, according to the second embodiment, the Ta film formed the second time has a uniform structure.

As described above, by forming the Ta film in two steps, the Ta film thus formed had a stress change of -3 MPa or less even 2000 hours after being exposed to the atmosphere. On the other hand, in the Ta film according to the first embodiment described above, a stress change of about −9 MPa was observed 1500 hours after being exposed to the atmosphere. Even if the Ta film is formed twice as in the second embodiment, the stress can be adjusted by the heat treatment after the film formation.

[0040]

As described in the foregoing, the production method of the inventions of the X-ray mask, first generates a plasma stream of xenon gas by electron cyclotron resonance in the vacuum vessel is evacuated to a predetermined degree of vacuum A plasma generating means and a target made of tantalum are prepared, a membrane is placed facing the plasma generating means in the direction of the plasma flow of the plasma generating means, and a plasma flow is placed between the plasma generating means and the membrane. The target is placed so as not to interfere. Then, a plasma flow is generated by the plasma generation means so that the membrane is exposed to the plasma flow , and the temperature of the membrane is 170 ° C. or higher.
As above , the ions in the plasma are accelerated to collide with the target and sputter to eject tantalum atoms, and the tantalum atoms are deposited on the surface of the membrane exposed to the plasma flow. A thin film made of a polycrystalline body was formed and a mask pattern was formed by processing this thin film. As a result,
The mask pattern is composed of tantalum in a state where oxygen is prevented from entering the crystal grain boundaries. Then, in the method for manufacturing an X-ray mask of the present invention, first, a plasma generating means for generating a plasma flow of xenon gas by electron cyclotron resonance and a target made of tantalum are provided in a vacuum container evacuated to a predetermined vacuum degree. The membrane is prepared, the membrane is placed facing the plasma generating means in the direction in which the plasma flow of the plasma generating means flows, and the target is arranged between the plasma generating means and the membrane so as not to obstruct the plasma flow. Then, first, a plasma flow is generated by the plasma generation means so that the membrane is exposed to this plasma flow , and
The temperature of the membrane is 170 ° C or higher , the ions in the plasma are accelerated to collide with the target, sputter to eject tantalum atoms, and the tantalum atoms are deposited on the surface of the membrane exposed to the plasma flow. A first thin film made of a polycrystal of α-phase tantalum is formed on the surface. Here, the deposition of tantalum atoms is once stopped for a predetermined time. Then, next, a plasma flow is continuously generated by the plasma generation means to bring the membrane into a state of being exposed to this plasma flow, ions in the plasma are accelerated to collide with a target and sputter to eject tantalum atoms, By depositing the tantalum atoms on the surface of the first thin film exposed to the plasma flow, a second thin film made of a polycrystal of α-phase tantalum is formed on the surface of the first thin film. The mask pattern is formed by processing the first thin film and the second thin film. Therefore, the upper part of the mask pattern is composed of the tantalum portion having a more stable crystal state, and the upper part of the mask pattern is more in a state in which oxygen is suppressed from entering the crystal grain boundaries more than the lower part of the mask pattern. Has become. As described above, according to the present invention, the mask pattern made of tantalum is
Since the manufacturing process is performed with the stress suppressed, the mask pattern can be manufactured with the positional deviation suppressed.

[Brief description of drawings]

FIG. 1 is a sectional view showing a structure of an X-ray mask according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram for explaining the manufacturing method of the X-ray mask in the first embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a configuration of a sputtering apparatus by the ECR sputtering method.

FIG. 4 is a characteristic diagram showing a result of measuring a change in stress after the Ta film according to the first embodiment is taken out into the atmosphere.

FIG. 5 is a photograph showing a result of observing a state of a Ta film with a transmission electron microscope (TEM).

FIG. 6 is a correlation diagram showing the relationship between the substrate temperature at the start of film formation and the stress of the formed Ta film.

FIG. 7 is a characteristic diagram showing a stress change of a Ta film due to heat treatment.

FIG. 8 is an explanatory diagram showing a state of positional deviation of a mask pattern formed of a Ta film.

FIG. 9 is a flowchart showing a film forming procedure in the first embodiment.

FIG. 10 is a flowchart showing a film forming procedure in the second embodiment.

FIG. 11 is a configuration diagram showing a configuration of an X-ray mask which has been conventionally used.

FIG. 12 is an explanatory diagram showing a method of manufacturing an X-ray mask.

FIG. 13 is an explanatory diagram showing a state where a mask pattern is displaced.

[Explanation of symbols]

101 ... X-ray mask, 102 ... Membrane, 103 ... Frame, 104 ... Mask pattern, 201 ... Silicon wafer, 202 ... Silicon nitride film, 203 ... Ta film, 20
4 ... Oxide film pattern.

Front page continuation (72) Inventor Seitaro Matsuo 3-19-2 Nishishinjuku, Shinjuku-ku, Tokyo Nihon Telegraph and Telephone Corporation (56) Reference JP-A-63-67732 (JP, A) JP-A-60 -50167 (JP, A) JP-A-7-11438 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 21/027 C23C 14/00 -14/58

Claims (3)

(57) [Claims] 1. A method of manufacturing an X-ray mask , comprising : an X-ray permeable membrane; and a mask pattern formed on the membrane to block X-rays. A vacuum container evacuated to a predetermined vacuum degree. Electronic cycle in
Generating a plasma flow of xenon gas by rotron resonance
Plasma generation means and a target made of tantalum
Prepare and flow the plasma flow of the plasma generating means
Facing the plasma generating means in the direction of
Place a blender on the plasma generator and the membrane.
The target so as not to interfere with the plasma flow between
A state of arranging the dot and temperature of the membrane and 170 ° C. or higher, and the flop
The plasma flow is generated by the plasma generation means to generate the plasma flow.
The bramble was exposed to this plasma flow, and the
Ions in the plasma are accelerated to collide with the target.
To sputter out tantalum atoms,
Surface of the membrane exposed to the plasma flow of the membrane.
By depositing on the surface, α-phase
Form a thin film made of a polycrystal of Ta and process the thin film to form the mask pattern.
A method of manufacturing an X-ray mask , comprising: 2. A membrane permeable to X-rays and this membrane
A mask pattern formed on the blend to block X-rays
In a method for manufacturing an X-ray mask including: an electronic cycle in a vacuum container evacuated to a predetermined vacuum degree.
Generating a plasma flow of xenon gas by rotron resonance
Plasma generation means and a target made of tantalum
Prepare and flow the plasma flow of the plasma generating means
Facing the plasma generating means in the direction of
Place a blender on the plasma generator and the membrane.
The target so as not to interfere with the plasma flow between
The Tsu bets placed, the temperature of the membrane and 170 ° C. or higher, and the flop
The plasma flow is generated by the plasma generation means to generate the plasma flow.
The bramble was exposed to this plasma flow, and the
Ions in the plasma are accelerated to collide with the target.
To sputter out tantalum atoms,
Surface of the membrane exposed to the plasma flow of the membrane.
By depositing on the surface, α-phase
A first thin film made of a polycrystal of tantalum is formed, the deposition of the tantalum atoms is stopped for a predetermined time , and then the plasma flow is generated by the plasma generating means.
The membrane is exposed to this plasma flow.
And accelerate the ions in the plasma to accelerate the target
Tantalum atoms are ejected by colliding with the
The tantalum atoms to the plasma of the first thin film.
The first thin film is deposited on the surface exposed to the flow.
Form a second thin film of α-phase tantalum polycrystal on the surface
Form, wherein by processing them first and the thin film and the second film
X-ray mask characterized by forming a mask pattern
Manufacturing method . 3. Production of the X-ray mask according to claim 1 or 2.
A method of manufacturing an X-ray mask, characterized in that, in the manufacturing method , after the thin film is formed, heat treatment is performed for a predetermined time .