JP2002168998A - Method for producing metal membrane and metal filter - Google Patents

Abstract

(57) [Problem] To provide a method for producing a metal membrane which is optically uniform and does not cause corrosion or property change. SOLUTION: An LP is provided on the front and back surfaces of a silicon single crystal substrate 1.
-A SiN film 2 serving as a support is formed by CVD or the like (a). Then, a resist 3 is applied on the back side, and is removed by a photolithography process, leaving a portion where a metal thin film is formed (b). Then, the SiN film 2 is removed by dry etching using SF ₆ gas, and then the resist is removed (c). Subsequently, the silicon single crystal substrate 1 is removed from the rear surface by dry etching using a fluorine-based active species, thereby producing SiN to be a support layer (d). Thereafter, a metal 4 such as Al or Ti is formed on the surface side of the SiN film 2 by vapor deposition, sputtering or the like (e). Finally,
From the back side, dry etching with SF ₆ gas
The iN film 2 is removed, and the metal membrane 4 is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

2. Description of the Related Art Conventionally, as a metal-based filter used in the vacuum ultraviolet region to the soft X-ray region, a thin film (thickness: 0.15 μm or more) of Al, Ti, In, Zr or the like is held by a mesh of stainless steel or the like. Those having a structure are generally used.

[0002] A method for manufacturing such a metal-based filter is as follows. First, NaCl is vacuum-deposited on a flat substrate such as a glass plate, and a desired thickness of a metal layer to be obtained as a membrane is formed on the NaCl layer by vapor deposition or the like. Immerse the whole board in water,
A method has been adopted in which a metal thin film is released from a substrate by dissolving a NaCl layer in water, and then scooped with a mesh such as stainless steel.

[0003]

However, the filter made by this method is shaded because the mesh portion supporting the metal thin film does not allow light to pass through, and is not optically uniform. I couldn't say it. In addition, corrosion of the mesh or the membrane due to the undissolved NaCl shortens the life of the filter or causes a change in the characteristics of the filter, thus causing a problem in reliability.

The present invention has been made in view of such circumstances, and provides a method for producing a metal membrane that is optically uniform and does not cause corrosion or change in characteristics, and a metal filter using the metal membrane. The task is to

[0005]

A first means for solving the above problem is to use a nitride membrane as a support layer when forming a metal layer, and then to dry etch a part of the nitride membrane. A method for producing a metal membrane, comprising a step of removing (claim 1)
It is.

In this means, a nitride membrane is used as a support layer, a metal layer membrane is formed thereon, and then a portion of the nitride membrane is removed by dry etching, thereby forming a portion of the nitride membrane. Exposing the metal layer membrane. The non-removed nitride membrane is used as a support for the metal layer membrane.

The reason why the nitride membrane is used as the support layer is that it has a characteristic that the strength is high, and it is not etched by wet etching when etching Si, but is easily etched by dry etching. Among nitrides, SiN _x and BN are preferable because of their excellent properties.

Also, dry etching is used to remove the nitride membrane because the metal membrane is very thin and weak in strength, so that it is easily broken by wet etching, and an etching solution is used when wet etching is used. And dry etching can be performed under weak conditions.

[0009] A second means for solving the above-mentioned problems is as follows.
The first means, wherein the nitride membrane is Si
A film is formed on a single crystal wafer substrate, and after the film is formed, a part of the Si single crystal wafer substrate is removed by etching (claim 2).

In the present means, when forming a nitride membrane, a method is employed in which a nitride membrane is formed on a Si single crystal wafer substrate, and then a part of the Si single crystal wafer substrate is removed by etching. ing. Accordingly, a thin and stable nitride membrane can be formed, and the remaining Si single crystal wafer substrate can be used as a support for the metal membrane.

A third means for solving the above-mentioned problem is as follows.
According to a third aspect of the present invention, there is provided a metal filter including a metal membrane manufactured by the method for manufacturing a metal membrane as the first or second means.

Since the metal filter according to the present invention does not have a mesh of stainless steel or the like, it is optically uniform and does not cause corrosion or change in characteristics.

A fourth means for solving the above-mentioned problem is as follows.
The third means, wherein the metal membrane is Al, T
It is characterized by being made of i, Zr or a metal containing these as a main component (claim 4).

These metals are suitable for use in the vacuum ultraviolet region to the soft X-ray region.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described.
This will be described with reference to the drawings. FIG. 1 shows Embodiment 1 of the present invention.
It is a figure showing the manufacturing method of the metal membrane which is an example. Ma
And LP-CVD etc. on the front and back of the silicon single crystal substrate 1.
To form a SiN film 2 having a thickness of about 1 μm as a support.
(A). In addition to the support, SiN _xAnd BN
Mechanically tough, different materials with a certain thickness on the membrane
Those capable of forming a high quality film can be used. Soshi
And apply a resist 3 on the back side to form a metal thin film
Photolithography, leaving a wider area than
(B). And the remaining Les
SF₆Dry etch with gas
The SiN film 2 is removed by etching, and then the resist is removed.
(C).

Subsequently, the silicon single crystal substrate 1 is removed from the back surface by dry etching using a fluorine-based active species to produce SiN to be a support layer (d). Then, Al,
A metal 4 such as Ti or Zr is formed on the surface side of the SiN film 2 by vapor deposition, sputtering or the like (e). Finally, from the back side, SF
_The SiN film 2 is removed by dry etching with ₆ gases to complete the metal membrane 4 (f). As an etching gas to be used, RIE, RIBE, ICP-E, which can etch a supporting membrane material and can adopt a condition that does not cause much damage to a metal-based membrane layer,
Radical beam etching or the like can be used. When the supporting membrane is SiN _x , the etching gas is CF ₄ , CHF
_3, SF _6, etc. to use the gas composition mainly composed of F-based gas preferably.

Since the metal membrane having the structure shown in FIG. 1F is supported by the Si single crystal 1, a tensile stress can be applied, and the metal membrane can be flattened. Especially effective for use.

[0018]

EXAMPLES (Example 1) An Al membrane according to an example of the present invention was manufactured using a vapor deposition process. First, a 0.1 μm-thick silicon nitride film having a low tensile stress is formed on both surfaces of a Si wafer substrate by LP-CVD, and a photolithography process and CF ₄ + O ₂ are formed on a part of the silicon nitride film on one surface (back surface). After opening a 5 mm square window by gas plasma, only the portion forming the opening at the center of the substrate is etched with a 1N (normative) -KOH solution at about 90 ° C., as shown in FIG. A silicon nitride membrane serving as a support layer was manufactured.

Next, Al was formed on the silicon nitride membrane in a thickness of 0.1 μm from the front side of the substrate by vacuum evaporation using an EB evaporation apparatus, and then SF ₆ gas 20 sccm was applied from the back side of the substrate by a parallel plate type RIE apparatus. An Al membrane without a support as shown in FIG. 1 (f) was manufactured under the conditions of a pressure of 25 mTorr, a power density of 0.16 W / cm ² and a time of 5 minutes. The etching gas when selectively removing the silicon nitride layer is set to a pressure of 10 to 100 mTorr and a power density of 0.02 to 0.1 W / m so as not to damage the Al membrane and to perform the etching. cm ² is preferred.

Example 2 A Ti membrane according to an example of the present invention was manufactured by a sputtering method. First, a 0.1 μm-thick silicon nitride film having a low tensile stress is formed on both surfaces of a Si wafer substrate by LP-CVD, and a photolithography process and CF ₄ + O are formed on a part of the silicon nitride film on one surface (back surface). After opening a window of 5 mm square by ₂ gas plasma, only a portion forming an opening at the center of the substrate is etched with a 1N (normal) -KOH solution at about 90 ° C., as shown in FIG. A silicon nitride membrane serving as a suitable support layer was manufactured.

Next, after a Ti film is formed to a thickness of 0.1 μm on the silicon nitride membrane from the surface direction of the substrate by a sputtering method,
CHF from the back side of the substrate by parallel plate type RIE
₃ + O ₂ gas 20sccm, pressure 30mTorr, power density 0.16W / cm ² ,
The silicon nitride layer was selectively removed under the condition of time 3 minutes, and FIG.
A Ti membrane without a support as shown in (f) was produced. The etching gas when selectively removing the silicon nitride layer is a pressure of 10 to 100 m so as not to damage the Ti membrane and to perform the etching.
The power density is preferably 0.02 to 0.1 W / cm ² .

(Example 3) The Al membrane obtained in Example 1 was used as a band-pass filter of radiation emitted from an SOR (synchrotron radiation) light source as shown in FIG. Physical property evaluation from vacuum ultraviolet region to X-ray region,
It is necessary to irradiate only a specific wavelength to the sample in the optical device evaluation and photoreaction process. However, when using a SOR light source with high brightness in this wavelength region, the spectrum of the light source contains from the infrared region to the X-ray region. It is necessary to arrange a filter having wavelength selectivity in front of the sample so that only a specific wavelength reaches the sample.

The Al membrane having a thickness of 0.1 μm obtained in Example 1 has a spectral transmission characteristic as shown in FIG. 3 in the soft X-ray region, and is disposed between the SOR light source and the sample as shown in FIG. Thus, it could be used as a bandpass filter having a transmission band of 25 to 100 eV. In this case, the beam line, the membrane filter, and the sample were placed in a high vacuum.

[Brief description of the drawings]

FIG. 1 is a diagram showing a method for manufacturing a metal membrane which is an example of an embodiment of the present invention.

FIG. 2 is a diagram showing an arrangement in a case where an Al membrane according to the present invention is used as a band pass filter of a SOR light source.

FIG. 3 is a view showing a spectral transmittance when an Al membrane according to the present invention is used as a filter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Silicon single crystal 2 ... SiN film 3 ... Resist 4 ... Metal membrane

Claims (4)

[Claims] 1. A method for producing a metal membrane, comprising using a nitride membrane as a support layer when forming a metal layer, and thereafter removing a part of the nitride membrane by dry etching. 2. The method for producing a metal membrane according to claim 1, wherein the nitride membrane is formed on a Si single crystal wafer substrate, and after the film formation, a part of the Si single crystal wafer substrate. A method for producing a metal membrane, characterized in that the method is formed by etching to remove metal. 3. A metal filter comprising a metal membrane produced by the method for producing a metal membrane according to claim 1. 4. The metal filter according to claim 3, wherein said metal membrane is made of Al, Ti, Zr or a metal containing these as a main component.