JPH0936016A - Membrane and mask, exposure apparatus and device manufacturing method using the same - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a membrane excellent in physical and mechanical strength, excellent in surface condition and light transmittance, and an excellent mask using the same. A mask membrane that transmits X-rays or vacuum ultraviolet rays is composed of a laminated film of SiC and SiCN. The laminated film is formed by forming a SiN film on one side or both sides of the Si film.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to the technical field of masks used in lithography for manufacturing devices such as semiconductors.

[0002]

2. Description of the Related Art It is widely used industrially, particularly in the field of electronic industry, to manufacture various products by partially modifying the surface of a material to be processed by using a lithography technique. A large amount of products having the same surface alteration can be manufactured. 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 an energy blocking material is partially arranged is used. As such a mask, when the irradiation energy is visible light or ultraviolet light,
A transparent substrate such as glass or quartz provided with a black opaque pattern such as silver or chrome is used.

However, with the demand for finer pattern formation, vacuum ultraviolet rays and X-rays having shorter wavelengths have been attracting attention. In the case of visible light or ultraviolet light, these energy rays cannot pass through the energy rays by the glass or quartz plate used as the mask substrate member, and are not suitable as the substrate material of the mask.

Therefore, in lithography using vacuum ultraviolet rays or X-rays, various inorganic thin films, for example, ceramic thin films of silicon, silicon nitride, silicon carbide, diamond, etc., or organic polymer thin films of polyimide, polyamide, polyester, etc., These laminated thin films are used as energy ray transmissive bodies, and metals such as gold, platinum, tungsten, tantalum, etc. are formed in a pattern on the surface of these films as energy ray absorbent bodies to form a mask.

[0005]

Among the candidates for the mask membrane material, Si, BN, SiN, and SiC can be mentioned as the ones that are close to practical use as inorganic materials. Of these, Si has been receiving particular attention recently.
It is.

A single crystal of Si has been widely used as a substrate material for semiconductors, and its position is considered to remain unchanged for the time being. What is ideal as a mask material for lithography is that the mask membrane material is the same as the transferred substrate material, that is, the coefficient of thermal expansion is exactly the same, and the thermal conductivity is also the same. Mask membranes are near ideal in this respect.

CV is used as a method for forming the Si membrane film.
D method, sputtering method, boron doping method of crystalline silicon, etc. have been reported. However, the properties of the formed film differ significantly depending on the film forming method. That is, the single crystal state of the Si wafer, polysilicon, amorphous silicon and the like. A number of problems still remain with these membranes, and although they have been working on improvements by taking manufacturing methods or additional means, they have not reached the basic solution.

The problems of the Si membrane film are listed as follows: (1) The surface condition is bad (in the case of sputtering film formation, etc., due to the growth of fine crystals) (2) Poor transmittance of alignment light (specific absorption, (Scattering within the film and on the surface) (3) Non-uniform film thickness (in-plane, within-lot, and between-lot control is difficult).

As measures against this, it has been proposed to polish the film surface after film formation and to vapor-deposit SiO ₂ as a translucency treatment. However, complicated and difficult post-treatments and translucency at the sacrifice of physical properties, mechanical strength and chemical strength are not essential solutions.

The present invention has been made to solve the problems of the above-mentioned conventional techniques, and uses a membrane which is excellent in physical and mechanical strength, and is excellent in surface condition and permeability. It is an object of the present invention to provide an excellent mask, and further provide an exposure apparatus and a device production method using this mask.

[0011]

Means for Solving the Problems The membrane of the present invention for solving the above-mentioned problems is characterized in that it is composed of a laminated film of Si and SiN.

Further, the mask of the present invention is characterized in that a mask pattern is formed on the membrane.

Here, it is preferable that the SiN film is laminated on one side or both sides of the Si film.

The mask manufacturing method of the present invention is characterized by including a step of forming a laminated film of Si and SiN on a substrate and a step of removing a predetermined region on the back surface of the substrate.

Here, it is preferable that the method further comprises the step of forming a radiation absorber pattern on the laminated film. Further, it is preferable to form the laminated film by a sputter deposition method and / or a CVD method.

Further, the exposure apparatus of the present invention is characterized by having a means for performing exposure using the above mask.

The device production method of the present invention is characterized by producing a device using the mask.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION

<Example 1> An example of a method of manufacturing a mask structure suitable for X-ray and vacuum ultraviolet lithography will be described below.

As shown in FIG. 1A, a silicon substrate 1 having a diameter of 3 inches and a thickness of 1 mm was prepared. SB for film forming equipment
Si is used as a sputtering target by using an R sputtering device.
A pure argon gas and a pure nitrogen gas were prepared as the crystal and the sputtering gas.

First, the ratio of the gas flow rates of argon and nitrogen was set to 2: 1 and sputtering was performed with an input power of 200 W and a gas pressure of 2 Pa. The SiCN film 2 having a thickness of about 0.4 μm was formed in 30 minutes. Further, sputtering was continuously performed using 100% argon gas, and the same power was used and the gas pressure was 0.
Film formation was performed at 5 Pa for 120 minutes to form a Si film 3 having a thickness of about 1.2 μm. Again, a SiN film was continuously formed on the Si film under the same conditions to a thickness of about 0.4 μm. When the stress of the laminated film thus produced was measured, it showed a tensile stress of 1 × 10 ⁻⁹ dyne / cm ² . In the present embodiment, both surfaces of the Si film are sandwiched with the SiN film, but the SiN film may be provided on only one surface of the Si film.

Next, as shown in FIG. 1B, a SiN film 4 having a thickness of about 2 μm was formed in a region other than the rectangular portion corresponding to the pattern on the back surface of the silicon substrate 1. This is 20x
A rectangular aluminum plate of 20 mm is fixed on the substrate to form a SiN film, and then the aluminum plate is removed.
Then, add 30% KOH to the silicon back etching device.
The solution was set at 110 ° C. for about 3 hours, and Si was removed by etching from the back surface of the substrate using the SiN film as a mask to form a radiation transmitting portion.

Next, as shown in FIG. 1 (C), a radiation absorber film 5 was formed on the formed laminated film by a similar sputtering deposition method using a tungsten target and an argon gas. The film forming conditions are an input power of 75 W and a gas pressure of 4 Pa.
The film thickness was 1 hour, and the tungsten film thickness was 0.8 μm. Then, a chromium film 6 is further formed on the absorber film 5 by 0.1
It was vapor-deposited in a thickness of μm.

Next, as shown in FIG. 1D, an EB resist 7 was applied to a thickness of 0.4 μm using a spin coater.
Then, after pre-baking the resist, a mask pattern was drawn with a line width of 0.3 μm using an EB drawing device, and a resist pattern of 0.3 μm was formed through a predetermined developing process. Subsequently, using Cl ₄ as an etching gas in a dry etching apparatus, an intermediate mask pattern 6 of 0.3 μm Cr was formed with the resist pattern 7 as a mask.
Then, after removing the resist by O2 gas plasma, S
The tungsten layer 5 was pattern-etched with F6 gas plasma to form a radiation absorber pattern of a tungsten material having a line width of 0.3 μm and a height of 0.8 μm. Finally, a doughnut-shaped frame 8 made of Pyrex glass having a diameter of 3 inches Φ and a thickness of 8 mm was adhered using an epoxy adhesive 9 to prepare a mask structure for lithography as shown in FIG. 1 (E).

As a modification, the step of removing a predetermined portion of the silicon substrate by back etching may be performed after the mask pattern is formed. The material of the radiation absorber is not limited to tungsten, but may be a simple substance or an alloy of heavy metals such as gold, platinum, tantalum, molybdenum, and nickel.

<Second Embodiment> A mask manufacturing method according to a second embodiment will be described below. This embodiment is characterized in that the CVD method is used for forming the laminated film of the membrane. In addition,
The description of the steps similar to those in the first embodiment will be simplified.

A SiN film of about 0.5 μm is formed by a CVD method on a silicon substrate having a diameter of 3 inches and a thickness of 1 mm. Further C
Similarly, a Si film was laminated by about 1 μm by the VD method, and then about 0.5 μm of SiN was laminated.

Then, Cr 5 is used as an etching stopper layer.
00Å was deposited on the surface. Under the same conditions as in Example 1, W and Cr layers were further provided at 0.8 μm and 0.1 μm, respectively. After that, the radiation absorber pattern was formed through the same steps as in Example 1 above. Finally, oxygen plasma is applied to the C
Oxidation and translucency treatment of r was performed.

<Embodiment 3> A third embodiment of the present invention will be described. This embodiment is characterized in that the SiN film is formed by the sputtering method and the Si film is formed by the CVD method.

Si is formed on a silicon substrate by reactive sputtering.
An N film was formed to a thickness of 0.1 μm, then a Si film was deposited to a thickness of about 1.8 μm by the LP-CVD method, and a SiN film was formed to a thickness of 0.1 μm by the reactive sputtering method.

Since SiN also functions as an antireflection film for Si, it is possible to form a membrane film having a good alignment transmittance and a good surface property. Subsequent steps are the same as those in the above-described embodiment, and thus the description thereof will be omitted.

According to each of the embodiments described above, the following excellent operational effects can be obtained. (1) By providing the SiN film on the Si film surface, the surface condition of the membrane film surface can be improved. Si
N is an amorphous film and can prevent the deterioration of the surface state due to the precipitation of crystals. (2) Since the Si film is continuously formed on the amorphous film, the coarsening of the crystal can be improved, which means that not only the film surface of the alignment light but also the decrease due to internal scattering can be improved. . (3) By forming SiN so as to form a reflection film of Si, the transmittance of alignment light and the loss due to scattering can be greatly improved. (4) Since the Si film and the SiN film can arbitrarily obtain tensile and compressive stresses depending on the film forming conditions, a film having a smaller tensile stress can be obtained in the stacked layers. (5) In the sputter deposition method, it is possible to continuously form films by changing the gas type using the same target, and it is possible to easily form a laminated film.

<Embodiment 4> Next, an embodiment of an X-ray exposure apparatus using the X-ray mask produced as described above will be described. FIG. 2 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 5> 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. 3 shows the 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 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 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. 4 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. In step 14 (ion implantation), ions are implanted 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 process, PEB (Post Expo
sure Bake) process is included. In step 18 (etching), portions 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 production method of this embodiment, it is possible to produce a highly integrated semiconductor device, which was difficult in the past.

[0036]

As described above, according to the present invention, it is possible to provide a membrane which is excellent in physical and mechanical strength and is excellent in surface condition and light transmittance, and an excellent mask using the same.

Further, according to the exposure apparatus and device production method using the mask of the present invention, it is possible to perform exposure and device production with higher accuracy than ever before.

[Brief description of drawings]

FIG. 1 is a diagram showing a structure and a manufacturing method of a mask structure according to an embodiment of the present invention.

FIG. 2 is an overall configuration diagram of an embodiment of an X-ray exposure apparatus.

FIG. 3 is a diagram showing an overall flow of semiconductor device production.

FIG. 4 is a diagram showing a detailed flow of a wafer process.

[Explanation of Codes] 1 Silicon substrate 2 SiN membrane layer 3 Si membrane layer 4 Back etching window 5 X-ray absorber layer (tungsten) 6 Intermediate mask layer (chrome) 7 Resist layer (for EB) 8 Ring frame 9 Adhesive

Claims (8)

[Claims] 1. A membrane comprising a laminated film of Si and SiN. 2. A mask, wherein a mask pattern is formed on the membrane according to claim 1. 3. The membrane according to claim 1, wherein the SiN film is laminated on one side or both sides of the Si film, or the mask according to claim 2. 4. A mask manufacturing method comprising: a step of forming a laminated film of Si and SiN on a substrate; and a step of removing a predetermined region on the back surface of the substrate. 5. The mask manufacturing method according to claim 4, further comprising the step of forming a radiation absorber pattern on the laminated film. 6. The membrane according to claim 1, or the mask according to claim 2, wherein the laminated film is formed by a sputter deposition method and / or a CVD method. 7. An exposure apparatus comprising means for performing exposure using the mask according to claim 2 or 3. 8. A device production method comprising producing a device using the mask according to claim 2.