JP5196493B2 - Plasma processing equipment - Google Patents

Description

  The present invention relates to a plasma processing apparatus such as a plasma etching apparatus, a plasma CVD apparatus, and a plasma cleaning processing apparatus.

Nanoimprint technology has attracted attention as a technology for forming fine patterns on substrates such as semiconductor substrates, optical memories, holograms, and photonic crystals. Nanoimprint is a technology for transferring a predetermined pattern to the base material by embossing a mold having the same pattern as the pattern to be formed on the base material against a resist thin film formed on the surface of the base material. . In the conventional nanoimprint, a predetermined pattern is transferred to a base material using a mold in which a concavo-convex pattern is formed by etching on a flat substrate surface such as silicon or quartz.
On the other hand, in order to increase the efficiency of pattern transfer processing, a method of transferring a pattern to a substrate by rotating a cylindrical mold (roller mold) has been proposed (Patent Literature). 1, see Patent Document 2). Each of the molds disclosed in Patent Documents 1 and 2 is formed by curving a flat plate-like substrate having a pattern and attaching it to the outer peripheral surface of a cylindrical member.

JP 2008-73902 A Japanese Unexamined Patent Publication No. 2005-5284

However, in the case where the substrate is attached to the cylindrical member, the substrate may be damaged when the substrate is bent. In order to prevent breakage during bending, it is necessary to form a pattern on the substrate in consideration of the material, thickness, bending direction, and the like. Further, when the joint of the substrate attached to the cylindrical member becomes convex, a pattern defect due to the joint occurs during transfer.
The problem to be solved by the present invention is to provide a plasma processing apparatus capable of easily and accurately processing the outer peripheral surface of a cylindrical base material.

The plasma processing apparatus according to the present invention, which has been made to solve the above-mentioned problems, is an apparatus for plasma processing a cylindrical base material, which is a mold for nanoimprinting, having a processed surface on which a fine uneven pattern is formed on the outer periphery. Because
a) a vacuum vessel;
b) a columnar cathode electrode that is erected in the vacuum vessel and in which the cylindrical substrate is disposed on the outer periphery;
c) a high frequency power source for supplying high frequency power to the cathode electrode;
d) a cylindrical anode electrode concentrically with the cathode electrode, disposed opposite the outer peripheral surface of the cathode electrode;
The provided in the vacuum chamber, and a space at the bottom of the anode electrode is formed.
Another aspect of the plasma processing apparatus according to the present invention, which has been made to solve the above-described problems, is a cylindrical substrate that is a mold for nanoimprinting that has a surface to be processed on which a fine uneven pattern is formed on the outer periphery. A plasma processing apparatus for plasma processing a material,
a) a vacuum vessel;
b) a columnar cathode electrode that is erected in the vacuum vessel and in which the cylindrical substrate is disposed on the outer periphery;
c) a high frequency power source for supplying high frequency power to the cathode electrode;
d) a ring member that is disposed at the lower part of the outer periphery of the cathode electrode and on which the cylindrical substrate is placed;
e) an anode electrode disposed opposite the outer peripheral surface of the cathode electrode;
The height of the cathode electrode is higher than the sum of the height of the cylindrical substrate and the height of the ring member.

  In the plasma processing apparatus of the present invention, when high frequency power is supplied to the cylindrical cathode electrode, plasma is formed around the cathode electrode, and a sheath is formed on the outer peripheral surface of the cathode electrode. Therefore, by arranging the cylindrical base material on the outer peripheral portion of the cathode electrode, the entire outer peripheral surface of the cylindrical base material can be directly and simultaneously subjected to plasma treatment. For this reason, it is possible to eliminate variations in processing accuracy in the circumferential direction or the axial direction on the outer peripheral surface of the cylindrical base material. In particular, in an apparatus for forming a fine uneven pattern on the outer peripheral surface of a cylindrical base material by plasma etching, the pattern by a seam is different from that in which a plate-like base material is curved and attached to a cylindrical member. No defects will occur.

1 is a schematic overall configuration diagram of a plasma etching processing apparatus according to an embodiment of the present invention. The perspective view which shows the external appearance of an electrode. The perspective view which shows the lower surface of an electrode.

  Hereinafter, an embodiment in which the present invention is applied to a plasma etching apparatus will be described with reference to the drawings. FIG. 1 is an overall configuration diagram of a plasma etching apparatus according to the present embodiment. The plasma etching apparatus 1 has a vacuum vessel 5 composed of a lid 3 and a substrate 4. The lid 3 can be rotated in the vertical direction, and when the upper opening of the base 4 is closed by the lid 3, the inside of the vacuum vessel 5 is almost sealed.

  A disk-shaped electrode holding portion 6 is disposed in the lower part of the vacuum vessel 5, and a columnar electrode (cathode electrode) 7 is detachably held by the electrode holding portion 6. The electrode 7 is connected to a high frequency power source 10 via a matching box 8 and an output regulator 9. By adjusting the high frequency power by the output adjuster 9, the thickness (height dimension) of the sheath generated on the surface of the electrode 7 is adjusted.

FIG. 2 is a perspective view showing the electrode 7 held by the electrode holding portion 6, and FIG. 3 is a perspective view of the lower portion of the electrode 7 as viewed from below. The electrode 7 is made of a solid metal member such as aluminum, and has a screw hole 7a formed on the lower surface thereof. A mounting screw (not shown) is provided on the upper surface of the electrode holding portion 6, and the electrode 7 is detachably fixed to the electrode holding portion 6 by screwing the screw hole 7 a into the mounting screw.
A cylindrical base material 11 that is an object to be processed is arranged on the outer peripheral portion of the electrode 7 fixed to the electrode holding portion 6. A ring-shaped member 12 is disposed at the lower part of the outer peripheral portion of the electrode 7, and the cylindrical base material 11 is disposed on the outer peripheral portion of the electrode 7 while being placed on the ring-shaped member 12. The outer diameter dimension of the electrode 7 is set to be substantially the same as the inner diameter dimension of the base material 11, and the base material 11 arranged on the outer peripheral portion of the electrode 7 has the entire inner peripheral surface substantially the same as the outer peripheral surface of the electrode 7. It comes to touch. Here, “substantially in contact” means that a slight gap (a gap having a thickness of about 1 mm) exists between the inner peripheral surface of the substrate 11 and the outer peripheral surface of the electrode 7. Further, the electrode 7 has a height dimension such that the upper end portion of the base material 11 installed on the outer peripheral portion of the electrode 7 is positioned slightly below the upper end portion of the electrode 7. Thereby, the base material 11 is arrange | positioned among the outer peripheral surfaces of the electrode 7 in the intermediate part except a lower end part and an upper end part.

  A cylindrical deposition member 14 is disposed concentrically with the electrode 7 inside the vacuum vessel 5 and on the outer periphery of the electrode 7. The deposition preventing member 14 is electrically connected to the vacuum vessel 5 and has a ground potential. The adhesion preventing member 14 also functions as an anode electrode.

  On the other hand, the base 4 is provided with an exhaust pipe 18 connected to a vacuum pump (not shown), and the inside of the vacuum vessel 5 is evacuated by the operation of the vacuum pump. The base 4 is provided with a gas inlet 20 for introducing an etching gas into the vacuum vessel 5. A pipe 22 from a gas supply source (not shown) is connected to the gas inlet 20. An inlet tube 26 that guides gas to the manifold 24 at the upper end of the deposition preventing member 14 in the vacuum vessel 5 is connected to the pipe 22. The gas guided to the manifold 24 is distributed and supplied from the upper end of the deposition preventing member 14 to the internal space of the deposition preventing member 14. Thereafter, it flows into the space between the adhesion preventing member 14 and the base 4 from the lower end of the adhesion preventing member 14 and is discharged from the exhaust pipe 18. Therefore, the deposition preventing member 14 also functions as a current plate for the gas supplied into the vacuum vessel 5.

Next, the operation when plasma etching is performed on the cylindrical substrate 11 will be described.
First, after the base material 11 is disposed on the outer periphery of the electrode 7 via the ring-shaped member 12, the inside of the vacuum vessel 5 is decompressed to, for example, 0.005 to 1 Pa. When the pressure in the vacuum vessel 5 is higher than this range, the etchant does not enter the substrate 11 in the vertical direction, and pattern defects tend to occur. When the pressure is lower than the above range, plasma tends to be difficult to maintain. is there. By setting the pressure in the vacuum vessel 5 within the above range, it can be precisely etched in the vertical direction with respect to the substrate 11, and even a concave and convex pattern having a fine size of about several tens of nm can be formed well. can do.

  Subsequently, an etching gas is introduced into the vacuum vessel 5 and a high frequency voltage is applied to the electrode 7. Thereby, plasma is formed in the space between the electrode 7 and the deposition preventing member 14. In this case, if there is a gap larger than 1 mm between the inner peripheral surface of the base material 11 and the outer peripheral surface of the electrode 7, the plasma shape may be uneven. Since the inner peripheral surface of 11 and the outer peripheral surface of the electrode 7 are almost in contact with each other, uniform plasma is formed. As the etching gas, an appropriate gas corresponding to the type of the substrate 11 is selected. For example, when the substrate 11 is quartz, a fluorine-based gas such as CHF3, a mixed gas of hydrogen and fluorine, or the like can be used. In the nanoimprint, since the concavo-convex pattern is very fine, a gas that tends to generate a solid (resin) when plasma is generated may fill the formed concavo-convex pattern. Therefore, it is preferable to use a gas species such as a mixed gas of hydrogen and fluorine that does not generate a solid (resin) when plasma is generated.

When plasma is formed, a sheath region is formed on the surface of the electrode 7. In the sheath region, the ion density is higher than the electron density, and the positive ions in the plasma are accelerated and reach the surface of the substrate 11 perpendicularly (from the normal direction) to react with the substrate 11. Thereby, the surface of the base material 11 which is not covered with the mask pattern is etched vertically, and the uneven pattern is uniformly formed on the entire surface of the base material 11 itself. At this time, since the base material 11 is disposed in an intermediate portion where a stable sheath region is formed in the outer peripheral portion of the electrode 7, the uneven pattern formed on the base material 11 can be made favorable.
The thickness (height) of the sheath region depends on plasma generation conditions (applied voltage, gas pressure, interelectrode distance, etc.). In the present embodiment, the plasma generation conditions are adjusted so that the thickness of the sheath region is larger than the thickness of the substrate 11.
Next, specific examples will be described.

  In Example 1, a plasma processing apparatus (RIE-10N) manufactured by Samco Corporation was used. A cylindrical electrode 7 (diameter 20 cm, height 20 cm) made of aluminum is vertically installed in the processing chamber 5 of the plasma processing apparatus. A high frequency power supply 10 of 13.56 MHz and a regulator 9 for adjusting the high frequency output are connected to the electrode 7 through a matching box 8. A gas inlet 20 for introducing gas into the vacuum vessel 5 is provided on the side surface of the substrate 4. CHF3 (flow rate 10 sccm) was used as the gas. As the cylindrical base material 11, a quartz base material (outer diameter 21 cm, inner diameter 20.1 cm, height 20 cm) was used. A large number of photoresist mask patterns are formed in the shape of slits along the major axis on the surface of the cylindrical substrate 11 (mask pattern thickness 0.15 μm, slit width 20 nm).

The base material 11 is disposed on the outer periphery of the electrode 7, the pressure in the vacuum vessel 5 is reduced to 0.3 Pa, gas is introduced, and high frequency power (13.56 MHz) is applied to the electrode 7 to generate plasma. I let you. At this time, the sheath was uniformly generated within a range of 17 mm from the surface of the base material 11 so as to surround the base material 11.
After the plasma treatment was completed, the base material 11 was taken out from the vacuum vessel 5, and the mask pattern remaining on the surface of the base material 11 was cleaned and removed. And when the shape of the slit-shaped unevenness | corrugation formed in the base material 11 surface was measured, the unevenness | corrugation with a depth of 1.2 micrometers and a width | variety of 20 nm was uniformly formed in the whole base material 11 outer peripheral surface.

Next, using the cylindrical base material (hereinafter referred to as “mold”) after forming the concave / convex pattern, the concave / convex pattern is transferred to the acrylic photo-curing resin, and light is emitted from the inside of the cylindrical mold. An experiment of solidifying by irradiation with (ultraviolet light) was conducted. As a result, the uneven pattern of the mold could be transferred with high accuracy.
Next, since a small amount of resin residue remained in the uneven pattern of the mold, an experiment was conducted to remove the resin residue using the plasma processing apparatus shown in Example 1. The mold after the transfer experiment was placed on the outer periphery of the electrode 7, the pressure in the vacuum vessel 5 was reduced to 0.3 Pa, and then a mixed gas of argon and oxygen was introduced as a cleaning gas. After that, when high frequency power (13.56 MHz) was applied to the electrode 7 to generate plasma, it was possible to remove all the resin residues remaining in the concavo-convex pattern.

The present invention is not limited to the above-described embodiments and examples, and for example, the following modifications are possible.
In the above-described embodiment, the plasma on the surface of the base material is uniformly formed by arranging the cylindrical base material on the outer periphery of the intermediate portion excluding the upper and lower ends of the electrode. The plasma may be made uniform by rotating the base materials together or only the base material in the major axis direction.

Moreover, since the mold for nanoimprint has a fine uneven pattern, a resin residue may adhere to the uneven pattern of the mold after the uneven pattern is transferred to a transfer material such as a resin. The plasma processing apparatus of the present invention can also be used as a cleaning processing apparatus for removing resin residues from such a mold. That is, the mold after pattern transfer is arranged on the outer periphery of the cylindrical electrode, and oxygen, a mixed gas of inert gas such as oxygen and argon, a dilution gas such as oxygen and nitrogen, or oxygen A mixed gas of a gas and a gas containing F element such as Freon is introduced into the vacuum vessel. Then, by applying high-frequency power to the electrodes, a plasma treatment is performed on the substrate to remove resin residues.

DESCRIPTION OF SYMBOLS 1 ... Plasma etching apparatus 5 ... Vacuum container 7 ... Electrode (cathode electrode)
DESCRIPTION OF SYMBOLS 10 ... High frequency power supply 11 ... Base material 14 ... Prevention member (anode electrode)
16 ... Upper electrode

Claims (5)

A plasma processing apparatus for plasma processing a cylindrical base material, which is a mold for nanoimprint, having a processing target surface on which a fine uneven pattern is formed,
a) a vacuum vessel;
b) a columnar cathode electrode that is erected in the vacuum vessel and in which the cylindrical substrate is disposed on the outer periphery;
c) a high frequency power source for supplying high frequency power to the cathode electrode;
d) a cylindrical anode electrode concentrically with the cathode electrode, disposed opposite the outer peripheral surface of the cathode electrode;
The provided in the vacuum chamber, a plasma processing apparatus and a space at the bottom of the anode electrode is formed. A plasma processing apparatus for plasma processing a cylindrical base material, which is a mold for nanoimprint, having a processing target surface on which a fine uneven pattern is formed,
a) a vacuum vessel;
b) a columnar cathode electrode that is erected in the vacuum vessel and in which the cylindrical substrate is disposed on the outer periphery;
c) a high frequency power source for supplying high frequency power to the cathode electrode;
d) a ring member that is disposed at the lower part of the outer periphery of the cathode electrode and on which the cylindrical substrate is placed;
e) an anode electrode disposed opposite the outer peripheral surface of the cathode electrode;
The plasma processing apparatus is characterized in that the height of the cathode electrode is higher than the sum of the height of the cylindrical substrate and the height of the ring member. The anode electrode, the plasma processing apparatus according to claim 2, characterized in that it comprises the cathode electrode and the concentric cylindrical shape.   The plasma processing apparatus according to claim 1, wherein the anode electrode also serves as an adhesion preventing member.   The plasma processing apparatus according to claim 1, wherein a fine uneven pattern is formed on the outer peripheral surface of the cylindrical base material by plasma etching.

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