JP2011026676A - Plasma treatment apparatus and method for producing optical element forming die - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma treatment apparatus and a method for producing an optical element forming die, with which while equalizing the releasing directions of plasma, droplets and scattered particles can be easily removed, and the quality of surface treatment can be improved. <P>SOLUTION: The plasma treatment apparatus 1 is provided with: a plasma release part 10 having a target 6 and an anode electrode, and releasing plasma 8 by arc discharge; a deflection part 13 deflecting the plasma 8 and transporting the same to the surface of a die base material 11 for forming an optical element; and a shielding board 20 shielding a passage going straight from the surface of the target 6 to the die base material 11 for forming an optical element. The anode electrode is provided with: a circumferential electrode part where a plurality of arcuate conductors are arranged so as to circulate around the axial direction of the target 6, and the respective openings of the arcuate conductors are arranged at the side opposite to the die base material 11 for forming an optical element with the target 6 interposed; and a wiring part feeding electric current to the circulation electrode part. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a plasma processing apparatus and an optical element mold manufacturing method using the same.

Conventionally, in a reduced pressure atmosphere, an arc discharge is induced in a target material to generate a plasma containing ions of the target material, and this plasma is transported to the surface of the object to be processed. Various plasma processing apparatuses that perform ion implantation and film formation have been proposed.
As such a plasma processing apparatus, for example, Patent Document 1 describes a thin film forming apparatus using an arc electrode formed of a coil-shaped spiral body in which a target material is arranged in the axial center.
According to this thin film forming apparatus, when a current for causing an arc discharge flows to the arc electrode, a helical current flowing in the coil causes a magnetic field around the target material in the direction along the axis of the target material, and in the target material. A magnetic field that circulates around the axis of the target material is generated by the current flowing through the. And by the action of such a magnetic field, the plasma generation position is rotated along the axis direction while rotating around the axis of the target material, so that the deviation in the plasma emission direction is reduced and the plasma concentration distribution is uniform. It becomes. For this reason, the area | region which can form into a film uniformly is expanded compared with the case where a magnetic field is not generated.
Further, Patent Document 2 discloses that a magnetic field is applied to plasma emitted from a cylindrical arc electrode, thereby deflecting the plasma traveling direction, and electrically neutral droplets and scattered particles generated during arc discharge. Describes a surface treatment apparatus which can be separated from plasma by moving straight ahead.
According to this surface treatment apparatus, it is possible to prevent droplets and scattered particles from reaching the surface of the object to be processed, thus preventing occurrence of defects on the surface of the object to be processed due to the droplets and scattered particles. can do.

JP 2002-327262 A JP 2008-81797 A

However, the conventional plasma processing apparatus as described above has the following problems.
In the technique described in Patent Document 1, although the plasma concentration distribution can be equalized, it does not have a configuration for separating the plasma from the droplets and the scattered particles, so that the treatment is performed by the droplets and the scattered particles. Defects may occur on the surface of the body.
Further, in the technique described in Patent Document 2, since the arc electrode is cylindrical, it is difficult to form a magnetic field along the axial direction of the target, so that a bias in the plasma emission direction is likely to occur, compared with the case of Patent Document 1. As a result, uneven wear of the target occurs and the uniformity of the surface treatment is inferior.
Although it is conceivable to combine the coil-shaped arc electrode of Patent Document 1 and the plasma deflection means by the magnetic field of Patent Document 2, droplets and scattered particles that are electrically neutral and not affected by the magnetic field After passing through the gap of the arc electrode of the shape and scattering toward the object to be processed, or after colliding with the inner peripheral side of the coil of the arc electrode and being reflected, it passes through the gap of the arc electrode toward the object to be processed. Components that scatter are generated. For this reason, there exists a problem that the droplet and scattering particle | grains which reach a to-be-processed object cannot be removed favorably.

  The present invention has been made in view of the above problems, and can easily remove droplets and scattered particles while equalizing the plasma emission direction, thereby improving the quality of the surface treatment. It is an object of the present invention to provide a plasma processing apparatus and a method for manufacturing an optical element mold using the same.

In order to solve the above problems, a plasma processing apparatus of the present invention has a trigger electrode that generates a trigger discharge between an axial target and an anode electrode that induces an arc discharge between the targets. And a plasma emission part that emits plasma including ions of the target generated by the arc discharge in a direction toward the tip of the target, and the plasma emitted from the plasma emission part is deflected in a direction that intersects the axial direction of the target. And a deflection unit that transports the plasma to the surface of the object to be processed, and a path that is provided between the object to be processed and the anode electrode and that travels straight from the surface of the target toward the object to be processed. A plasma processing apparatus comprising: a shielding unit that performs an opening on one side of the anode electrode of the plasma emission unit The plurality of arch-shaped conductors are arranged so as to circulate around the target in the axial direction, and the openings of the plurality of conductors are arranged on the opposite side of the object to be processed across the target. And a wiring portion that supplies a current to the circumferential electrode portion.
According to the present invention, by performing trigger discharge from the trigger electrode of the plasma emission part to the target, arc discharge is induced between the circulating electrode part of the anode electrode and the target, and plasma including target ions is generated on the surface of the target. Can be generated. At that time, in an electric circuit formed by arc discharge, a magnetic field based on Ampere's law is generated by the current flowing through the circular electrode portion and the current flowing in the target. The magnetic field due to the current flowing through the circular electrode portion forms a magnetic field along the axial direction of the target by superposition, and the magnetic field due to the current flowing inside the target is a magnetic field that rotates in the right-handed direction toward the tip side of the target. For this reason, the arc current between the circular electrode portion and the surface of the target is subjected to a force that spirally rotates toward the base side of the target by the magnetic field in which these are superimposed. When arc discharge is generated at the base of the target exposed portion, the arc discharge position simply rotates with respect to the center axis of the target. Thereby, the plasma generation position on the target also moves with the movement of the target side position of the arc discharge.
The plasma emitted from the plasma emitting part is deflected by the deflecting part in a direction intersecting the axial direction of the target and transported to the surface of the object to be processed. At that time, since the position of the plasma at the time of emission rotates on the surface of the target, the emission position of the target plasma is equalized in the circumferential direction.
On the other hand, droplets and scattered particles generated from the target surface by arc discharge (hereinafter collectively referred to as scattered particles) are electrically neutral, and thus are scattered without being affected by the electromagnetic field. Since the shielding part is provided on the path that goes straight toward the object to be processed, even if the scattered granular material that scatters from the target toward the object to be processed passes through the gap between the surrounding electrode parts, the shielding part It is blocked by and cannot reach the object to be processed. In addition, since the opening of the conductor constituting the circular electrode portion is arranged on the opposite side to the object to be processed across the target, the scattered granular material scattered from the target toward the opposite side to the object to be processed is It is scattered outside the plasma emission part through the opening of the circular electrode part and separated from the plasma. For this reason, generation | occurrence | production of the scattering granular material which goes to a to-be-processed object side from the area | region and direction which are reflected by the surrounding electrode part and changes a scattering direction and is not shielded by a shielding part is suppressed.

Moreover, in the plasma processing apparatus of this invention, it is preferable that the said surrounding electrode part arrange | positions the central axis of the said substantially arched shape substantially coaxially with the central axis of the said target.
In this case, a magnetic field symmetric with respect to the center axis of the target is formed by superimposing the magnetic fields formed by the current flowing through the circular electrode portion during arc discharge. For this reason, the arc discharge position and the rotation axis of the spiral movement of the plasma on the target surface substantially coincide with the center axis of the target, and thereby the position of the plasma discharge position in the circumferential direction of the target surface is equalized well.

Moreover, in the plasma processing apparatus of this invention, it is preferable that the substantially arched shape of the said surrounding electrode part consists of circular arc shape.
In this case, a magnetic field that is rotationally symmetric with respect to the central axis of the target is formed by superimposing the magnetic fields formed by the current flowing through the circular electrode portion during arc discharge. For this reason, the rotational axis of the spiral movement of the plasma at the arc discharge position and the target surface substantially coincides with the center axis of the target, and the force from the magnetic field that causes the arc discharge position and the target surface to spiral move is also equalized in the circumferential direction of the target. The Thereby, the position of the plasma emission position in the circumferential direction of the target surface is equalized well.

The plasma processing apparatus of the present invention preferably includes a bias power supply unit that applies a bias voltage to the object to be processed.
In this case, by applying a bias voltage to the object to be processed by the bias power supply unit, it is possible to cause the target ions to collide with the object to be processed while adjusting the speed of the target ions transported in the vicinity of the object to be processed. For example, by controlling the magnitude of the bias voltage, the target ions can be accelerated and injected into the object to be processed, or the deposition amount can be dynamically controlled to form a film.

The manufacturing method of the optical element molding die of the present invention is a method of performing a surface treatment on the surface of a mold base material which is an object to be processed, using the plasma processing apparatus of the present invention.
According to this invention, since the surface of the mold base material is surface-treated by the plasma processing apparatus of the present invention, microscopic surface defects due to droplets and scattered particles are suitably suppressed, and high density and high adhesion strength are achieved. The surface which has can be obtained.

Further, in the method for manufacturing an optical element mold according to the present invention, the plasma generated by the plasma processing apparatus on the surface of the mold base material, which is an object to be processed, using the plasma processing apparatus including the bias power supply unit according to the present invention. It is preferable that ions of the target contained in the plasma are implanted or adhered, or implanted and adhered by applying a bias voltage to the object to be processed.
In this case, since the surface of the mold base material is surface-treated by the plasma processing apparatus including the bias power supply unit of the present invention, target ions contained in the plasma can be injected from the surface of the object to be processed into the inside, and the high density A surface having high adhesion strength can be obtained.

In the method for manufacturing an optical element mold according to the present invention, ions of the target contained in the plasma are implanted into the surface of the mold base material by changing the bias voltage applied to the object to be processed. It is preferable to make it adhere after making it.
In this case, since the protective layer having high adhesion strength can be formed, the durability of the optical element molding die can be improved.

According to the plasma processing apparatus of the present invention, since it has a surrounding electrode part having an opening on the opposite side to the object to be processed with the target interposed therebetween, and a shielding part for shielding a path that goes straight from the target toward the object to be processed, While equalizing the plasma emission direction, the droplets and scattered particles can be easily removed, and the quality of the surface treatment can be improved.
Moreover, according to the manufacturing method of the optical element shaping | molding die of this invention, since it manufactures using the plasma processing apparatus of this invention, there exists an effect that the quality of the die surface by which surface treatment was carried out can be improved.

It is a typical fragmentary sectional view of the front view which shows schematic structure of the plasma processing apparatus which concerns on the 1st Embodiment of this invention. It is the typical left view (A view of FIG. 1) which shows schematic structure of the anode electrode used for the plasma processing apparatus which concerns on the 1st Embodiment of this invention, and its BB sectional drawing. It is typical sectional drawing of the optical element shaping | molding die manufactured using the plasma processing apparatus of the 1st Embodiment of this invention. It is sectional drawing which shows a mode that the optical element of the 1st Embodiment of this invention is shape | molded. It is a typical fragmentary sectional view of the front view which shows schematic structure of the plasma processing apparatus which concerns on the 2nd Embodiment of this invention. It is the typical left view (E view of FIG. 5) which shows schematic structure of the anode electrode used for the plasma processing apparatus concerning the 2nd Embodiment of this invention, and its FF sectional drawing. It is a typical fragmentary sectional view of front view which shows schematic structure of the plasma processing apparatus which concerns on the 3rd Embodiment of this invention. It is typical sectional drawing of the optical element shaping | molding die manufactured using the plasma processing apparatus of the 3rd Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. In all the drawings, even if the embodiments are different, the same or corresponding members are denoted by the same reference numerals, and common description is omitted.

[First Embodiment]
A plasma processing apparatus according to a first embodiment of the present invention will be described.
FIG. 1 is a schematic partial sectional view in front view showing a schematic configuration of a plasma processing apparatus according to a first embodiment of the present invention. FIG. 2A is a schematic left side view (view A in FIG. 1) showing a schematic configuration of the anode electrode used in the plasma processing apparatus according to the first embodiment of the present invention. FIG. 2B is a BB cross-sectional view in FIG.
In addition, since each drawing is a schematic diagram, the shape and dimension are exaggerated (the following drawings are also the same).

The plasma processing apparatus 1 according to the present embodiment generates a plasma 8 containing ions of the target 6 under a reduced pressure atmosphere, transports the plasma 8 to the surface of the object to be processed, and processes the ions contained in the plasma 8. It is an apparatus for performing a surface treatment of an object to be processed by being injected into the body or attached to the surface of the object to be processed.
As shown in FIG. 1, the schematic configuration of the plasma processing apparatus 1 includes a vacuum chamber 2, in which a plasma emitting unit 10, a deflecting unit 13, a support 12, and a shielding plate 20 (shielding unit). Is arranged.
Outside the vacuum chamber 2 are a vacuum exhaust system (not shown) that adjusts the interior from atmospheric pressure to a predetermined pressure, a trigger power source 15 (see FIG. 2B), and an arc power source 16 (see FIG. 2B). Is provided.

As shown in FIGS. 2 (a) and 2 (b), the plasma emission unit 10 includes an axial target 6 connected to the trigger electrode 5 through a cylindrical insulator 3, and arc discharge around the target 6. The plasma 8 including target ions generated by arc discharge is emitted in a direction from the base end side of the target 6 toward the tip 6a.
In the present embodiment, the tip 6a is directed toward the center of the vacuum chamber 2 and the center axis O of the target 6 is substantially horizontal, and an insulating support member (not shown) is provided in the middle of the vacuum chamber 2 in the height direction. It is supported.

The target 6 can employ an appropriate metal material according to the type of material to be injected or adhered to the object to be processed by the plasma processing apparatus 1. In this embodiment, it is comprised from rod-shaped platinum as an example.
As an example, the shape of the target 6 of this embodiment employs a cylindrical shape having a diameter of 10 mm and a length of 40 mm.

As an example, the insulator 3 according to the present embodiment is a tube member made of a sintered body of tubular zirconium dioxide (ZrO ₂ ) having a thickness of 0.5 mm, and a heat-resistant adhesive, for example, an adhesive mixed with ceramic powder. Adhered to the outer periphery of the target 6 by alumina bond or the like.
Moreover, the trigger electrode 5 of the present embodiment is an annular member made of SUS304 that is externally fitted to the insulator 3, and the same heat-resistant adhesive as described above is applied to the end of the insulator 6 on the tip 6a side. Is fixed by bonding.

The anode electrode 7 of the plasma emission part 10 includes a circular electrode part 7A and a wiring part 7B.
The circular electrode portion 7A is formed into an arch shape by being curved in an arc shape between the base end portion 7b and the tip end portion 7c, and the base end portion 7b and the tip end portion 7c are separated to form an opening 7d. The plurality of arcuate conductors 7a (conductors). The arcuate conductors 7a are arranged in parallel at a constant pitch, with the arc centers of the arcs aligned on the same axis and the openings 7d oriented in a fixed direction.
Each base end portion 7b of the arcuate conductor 7a is connected to a wiring portion 7B made of a linear conductor that supplies current to the circular electrode portion 7A. For this reason, the anode electrode 7 has a plurality of arcuate conductors 7a attached to the curved comb teeth from the wiring portion 7B.
The anode electrode 7 has an inner diameter that allows the assembly including the target 6, the insulator 3, and the trigger electrode 5 to be inserted therethrough, and at least the tip 6 a of the target 6 is retracted inward, and the target as a whole. It is set as the magnitude | size which can cover 6 in an axial direction.

As an example, the arcuate conductor 7a of the anode electrode 7 of the present embodiment is made of an SUS304 wire having a wire diameter d = 3 (mm), an inner diameter D = 40 (mm), and the circumference is 5/6 of the circumference. It is curved into a circular arc shape with a central angle of 300 degrees. Thereby, an opening 7d having an angle of 60 degrees seen from the center of the arc of the arcuate conductor 7a is formed between the base end portion 7b and the tip end portion 7c.
Further, for the wiring portion 7B of the anode electrode 7, a straight wire material of SUS304 having a wire diameter d = 3 (mm) is adopted. Each base end portion 7b of the arcuate conductor 7a is connected to the wiring portion 7B by welding.
The arrangement pitch w of the arcuate conductors 7a is set to w = 2 × d = 6 (mm).

In the anode electrode 7, the arc center of each arcuate conductor 7 a is coaxial with the center axis O of the target 6 with respect to the target 6, and the opening 7 d of each arcuate conductor 7 a faces downward of the target 6. It is arranged in the state.
For this reason, the plurality of arcuate conductors 7 a of the anode electrode 7 are arranged above the target 6 so as to circulate around the central axis O of the target 6.
The position of the tip 6a of the target 6 is disposed on the inner side (right side in FIG. 2B) by 10 mm from the end of the anode electrode 7 in the axial direction.
Hereinafter, in the plasma emission part 10, an end part on the side where the tip 6 a of the target 6 is located is referred to as a tip part of the plasma emission part 10, and an end part on the base end side of the target 6 is a base end of the plasma emission part 10. Part.

The trigger power supply 15 is a power supply that applies a pulsed voltage to the trigger electrode 5 by a pulse signal from a control means such as a computer (not shown) in order to cause trigger discharge. In this embodiment, as an example, a voltage arbitrarily set in the range of 0 kV to 5 kV can be applied between the target 6 and the trigger electrode 5 with a pulse width of 5 μsec.
In the trigger power supply 15, the positive connection terminal 15 a is connected to the end surface of the trigger electrode 5 opposite to the tip 6 a of the target 6, and the negative connection terminal 15 b is connected to the base end side of the target 6.

The arc power supply 16 is a power supply provided with a capacitor (not shown) for causing arc discharge. In the present embodiment, as an example, a power supply that has a capacity capable of charging an electric quantity of about 8800 μF and that can arbitrarily set a voltage in the range of 0 V to 100 V is employed.
In the arc power supply 16, the positive connection terminal 16 a is connected to the wiring portion 7 B of the anode electrode 7, and the negative connection terminal 16 b is connected to the proximal end side of the target 6.

As shown in FIG. 1, the deflection unit 13 includes a ring-shaped magnet 17 having a central axis in the horizontal direction in the drawing, and an iron L-shaped yoke 18 that adjusts the direction of the lines of magnetic force generated from the magnet 17. ing.
The L-shaped yoke 18 of the present embodiment includes a side portion 18A extending in the vertical direction on the base end side of the plasma emitting portion 10 and a tip end of the plasma emitting portion 10 from the upper end of the side portion 18A toward the horizontal direction. The side portion 18B extends to the side, and is fixed in the vacuum chamber 2 by a support member (not shown).

The side portion 18A is provided with a through hole 18a through which the proximal end portion of the plasma emitting portion 10 is inserted. And the magnet 17 is arrange | positioned so that a magnetic pole may be formed in the direction in alignment with the central axis O of the target 6 in the outer peripheral side of this through-hole 18a.
For this reason, the proximal end portion of the plasma emitting portion 10 is disposed on the radially inner side of the magnet 17.
In addition, the side portion 18B is provided with a through hole 18b penetrating in the vertical direction at an end portion on the front side of the tip portion of the plasma emitting portion 10 in the horizontal direction.

According to such a configuration of the deflection unit 13, the direction of the magnetic lines of force of the magnet 17 is adjusted by the L-shaped yoke 18, and the vacuum chamber 2 is sandwiched between the side portion 18B and the side portion 18A below the side portion 18B. In the inner space, a magnetic field represented by magnetic field lines curved from the vicinity of the through hole 18a toward the vicinity of the through hole 18b is formed. Hereinafter, this magnetic field is referred to as a spatial magnetic field by the magnet 17.
This spatial magnetic field deflects the plasma 8 emitted from the plasma emission part 10 and transports it to the vicinity of the side part 18B. Therefore, the shape of the L-shaped yoke 18 and the arrangement of the magnets 17 are set so that the plasma 8 distribution necessary for the surface treatment of the object to be processed is obtained in the vicinity of the side portion 18B.
In the present embodiment, as shown in FIG. 1, the magnetic field lines of the spatial magnetic field become dense in the range of the region V on the outer peripheral portion on the side portion 18A side of the through hole 18b, and the plasma 8 necessary for the surface treatment is transported. On the opposite side (the left side in the figure) from the side 18A, the lines of magnetic force are rough so that the plasma 8 is not substantially transported.

The support base 12 is a member for supporting the optical element molding die base material 11, which is an object to be surface-treated, at a position on the path of the magnetic field lines of the spatial magnetic field by the magnet 17.
In this embodiment, it is formed in a substantially disc shape, and is fixed to a shaft 21 whose end is fixed to the vacuum chamber 2 and inserted through the through hole 18b. Thus, the support base 12 is disposed in the vicinity of the lower side of the side portion 18B so that the central axis C of the disk is substantially coaxial with the through hole 18b of the side portion 18B of the L-shaped yoke 18 and along the substantially vertical direction. Has been. For this reason, the support base 12 of this embodiment is arrange | positioned diagonally above the plasma emission part 10, and the positional relationship in which the central axis C of the support base 12 and the central axis O of the target 6 of the plasma emission part 10 are substantially orthogonal. Is provided.
The surface of the support base 12 on the side of the plasma emitting portion 10 (lower side) can support the optical element molding die base material 11.
The optical element molding die base material 11 is supported by the support base 12 on the supported surface 11b opposite to the treated surface 11a with the treated surface 11a (the surface of the object to be treated) facing downward. ing.

The shielding plate 20 is provided between the optical element molding die base material 11 held on the support base 12 and the anode electrode 7 of the plasma emission part 10, and is formed from the target 6 to the optical element molding die base material 11. It is a member that shields the path that goes straight toward.
The material of the shielding plate 20 is a non-magnetic material so as not to be affected by the magnetic force of the deflection unit 13.

Next, the operation of the plasma processing apparatus 1 of the present embodiment will be described using an example in which surface treatment is performed on the surface of the optical element molding base material 11.
FIG. 3 is a schematic cross-sectional view of an optical element molding die manufactured using the plasma processing apparatus according to the first embodiment of the present invention. FIG. 4 is a cross-sectional view showing how an optical element is molded using this optical element mold.

As shown in FIG. 4, the optical element molding die 23 shown in FIG. 3 is a mold member for forming a first lens surface 26b which is a concave surface of a lens 26 made of a convex-concave lens.
In order to manufacture the optical element molding die 23, first, for example, a material such as tungsten carbide is cut into a substantially cylindrical shape, and is supported in a planar shape for supporting the support table 12 on one end side in the axial direction. The surface 11b is formed, and the processed surface 11a having a convex shape for forming the concave surface of the first lens surface 26b on the other end side in the axial direction is mirror-finished to manufacture the optical element molding die base material 11.
Then, using the plasma processing apparatus 1, a film body 23 </ b> A, which is a thin film layer of platinum, is formed on the processing surface 11 a of the optical element molding base material 11 in order to improve the durability of the processing surface 11 a.

In order to form the film body 23A on the processing target surface 11a of the optical element molding die base material 11, first, as shown in FIG. 1, a plurality of optical element molding die base materials 11 for performing surface treatment are respectively supported. The base 12 is mounted so that the supported surface 11b is in close contact therewith.
Next, the inside of the vacuum chamber 2 is evacuated by an evacuation system (not shown), and the pressure is reduced to, for example, a vacuum degree of about 1 × 10 ⁻⁴ Pa or less. A voltage of 90 V is applied between the target 6 and the anode electrode 7. Since it is under reduced pressure, even if a voltage is applied between the target 6 and the anode electrode 7, no discharge occurs and a standby state is established.

In this state, a pulse signal is sent to the trigger power source 15 from a control means (not shown), the trigger power source 15 is operated, and a high voltage pulse voltage, for example, a voltage of 3 kV, for example, 5 μsec is applied between the target 6 and the trigger electrode 5. . At this time, creeping discharge (trigger discharge) occurs instantaneously at the tip of the insulator 3, current flows between the trigger electrode 5 and the target 6 protruding from the insulator 3, and an arc spot is formed on the surface of the target 6. Plasma is generated together with S _A (see FIG. 2B).

By plasma target 6 is generated slightly from the arc spot S _A, an electrical circuit is formed between the target 6 and the anode electrode 7, an arc discharge occurs between the anode electrode 7 and the target 6. Then, electricity stored in a capacitor (not shown) wired to the arc power source 16 instantaneously flows from the wiring portion 7B to the surrounding electrode portion 7A and arcs from the surface of the surrounding electrode portion 7A toward the surface of the target 6. The current I _A flows through the space and flows from the surface of the target 6 in the direction along the central axis O of the target 6 in the target 6 toward the negative electrode of the arc power supply 16. The high temperature arc spot S _A vicinity of the surface of the target 6, the plasma is generated in accordance with the magnitude of the arc current I _A.
This arc discharge is continued until the discharge of the amount of electricity stored in a capacitor (not shown) of the arc power supply 16 is completed. In this embodiment, this discharge time is about 600 μsec.

Assuming that the current value flowing from the positive electrode to the negative electrode of the arc power supply 16 during this arc discharge is I (t) (t represents time), I (t) is a mountain time that takes the maximum value in the middle of the discharge time. Showing change.
The current I (t) flows in the circular electrode portion 7A from the proximal end portion 7b to the discharge position toward the distal end portion 7c in each arc-shaped conductor 7a. In accordance with Ampere's law, a counterclockwise magnetic field is generated in the plane of FIG. With these magnetic fields, a magnetic field component in the direction from the front end to the base end of the plasma emission unit 10 is generated on the inner peripheral side of the circular electrode portion 7A, as in the case where the winding coil is energized.
The inner peripheral side arc current flows in the radial direction I _A of the orbiting electrode portion 7A is thus to flow across the generated magnetic field, electromagnetic force in the counterclockwise direction in the plane of FIGS. 2 (a) The magnetic field component Receive. Therefore, the arc current I _A, as well as arc spot S _A, in the paper plane of FIG. 2 (a), the is rotated counterclockwise about the central axis O.
As a result, the plasma generation position moves in the circumferential direction of the target 6.

Superposition of the results of these field components, the arc current I _A, as well as arc spot S _A, between the orbiting electrode portion 7A and the surface of the target 6, is circular movement about axis O of the target 6. Thereby, the plasma, which is a collection of charged particles generated on the surface of the target 6, spirally rotates around the central axis O of the target 6 on the inner peripheral side of the circulating electrode portion 7 </ b> A, and the electromagnetic force from the magnetic field is generated. It is received and accelerated while moving to the tip 6a side, and is emitted as plasma 8 (see FIG. 1) to the tip side of the plasma emitting portion 10.

  In this way, the plasma 8 is moved around the central axis of the target 6 while the arc discharge continues, and is moved to the distal end side of the plasma emitting portion 10 from the target 6 to the distal end side of the plasma emitting portion 10. Since it is emitted, the concentration distribution of the plasma 8 at the tip of the plasma emission part 10 is substantially equalized and emitted forward.

At this time, in this embodiment, since the center axis of the arc of the arcuate conductor 7a is arranged substantially coaxially with the center axis O of the target 6, it is symmetrical with respect to the center axis O of the target 6 during arc discharge. A strong magnetic field is formed. For this reason, the arc discharge position and the rotational axis of the spiral movement of the plasma on the target surface substantially coincide with the central axis O of the target 6, and thereby the position of the plasma discharge position in the circumferential direction of the target surface is equalized well.
In the present embodiment, since the arcuate conductor 7a is employed, a magnetic field that is rotationally symmetric with respect to the center axis of the target is formed. For this reason, the rotational axis of the spiral movement of the plasma at the arc discharge position and the target surface substantially coincides with the center axis of the target, and the force from the magnetic field that causes the arc discharge position and the target surface to spiral move is also equalized in the circumferential direction of the target. The Thereby, the position of the plasma emission position in the circumferential direction of the target surface is equalized well.

Although the plasma 8 emitted from the tip of the plasma emission part 10 is diffused in the radial direction, it is emitted in the direction along the central axis O of the target 6 as a whole.
The plasma 8 emitted from the plasma emission unit 10 is deflected so as to be wound around the magnetic field lines of the spatial magnetic field formed by the deflection unit 13. For this reason, the plasma 8 is transported along a path where the magnetic field lines of the spatial magnetic field are dense, and passes through the side portion of the shielding plate 20 toward the region V.
Then, the plasma 8 containing ions of the target 6 reaches the processing surface 11a of the optical element molding base material 11 arranged in the region V and collides with the processing surface 11a, and according to the kinetic energy, It is injected into or attached to the surface 11a to be processed. Thereby, a film body 23A made of the material of the target 6 is formed on the surface 11a to be processed.

On the other hand, the arc discharge, as in addition to scattering granules 19 of the plasma 8 (see FIG. 1), and the droplet is arc spot S _A liquid splashes melted in, Ya particle droplets solidified into scattered Scattered particles composed of impurity particles contained in the target 6 are generated. Since these scattering particles 19 are electrically neutral, they are scattered in the direction of the initial velocity without being affected by the magnetic field in the anode electrode 7 or the magnetic field by the deflecting unit 13. In general, since the mass of the scattering granular material 19 is small, the influence of gravity is small, and at the initial stage of the scattering stroke, it may be considered that the particle travels substantially linearly in the direction of the initial velocity.

In the present embodiment, a shielding plate 20 is disposed between the target 6 and the optical element molding die base material 11 disposed in the region V. For this reason, the scattering granular material 19 that passes through the gaps of the respective arcuate conductors 7a of the circular electrode portion 7A and scatters from the surface of the target 6 toward the optical element molding base material 11 disposed in the region V is It is prevented from colliding with the shielding plate 20 and reaching the optical element molding die base material 11.
Further, in the circumferential electrode portion 7A, an opening 7d is formed on the side opposite to the optical element molding die base material 11 disposed in the region V with the target 6 interposed therebetween. For this reason, as shown in FIG. 1, most of the scattered granular material 19 scattered from the surface of the target 6 to the side opposite to the optical element molding die base material 11 disposed in the region V passes through the opening 7d. Splash down.
The scattered granular material 19 scattered downward finally falls onto the bottom surface of the vacuum chamber 2 due to gravity.
For this reason, the scattered granular material 19 reaches the processing surface 11a of the optical element molding die base material 11 disposed in the region V, and unevenness is generated on the processing surface 11a due to the collision and adhesion of the scattering granular material 19. Or the occurrence of defects can be prevented.

Further, for example, when a case where the winding coil crosses a position corresponding to the opening 7d as in a known winding coil-shaped anode electrode is scattered obliquely downward from the target 6 toward the tip 6a. The scattered granular material 19 is reflected obliquely upward by the crossing portion of the winding coil and scattered from the gap between the upper winding coils toward the object to be processed.
According to the reflection by the winding coil at the position corresponding to the opening 7d, it is as if the starting point of the scattering of the scattering granular material 19 is expanded outside the range of the size of the target 6 in the horizontal plane. Has an effect. For this reason, the scattering granular material 19 which cannot be shielded by the shielding plate 20 that shields the straight path from the surface of the target 6 reaches the surface 11 a to be processed of the optical element molding base material 11.
In this case, it is conceivable to enlarge the size of the shielding plate 20, but the transport path of the plasma 8 deflected from the tip of the plasma emission part 10 is narrowed, and there is a problem that the efficiency of the surface treatment is deteriorated. .
According to the present embodiment, by providing the opening 7d, the probability that the scattered granular material 19 scattered downward from the target 6 is reflected downward is remarkably reduced. Therefore, it is possible to prevent the scattered granular material 19 from reaching the surface 11a to be processed without enlarging the size of the shielding plate 20, and thus without narrowing the transport path of the plasma 8.

  In this way, only the clean plasma 8 that is not mixed with the scattered granular material 19 passes through the side of the shielding plate 20 and reaches the surface 11a to be processed of the optical element molding base material 11 arranged in the region V. The surface treatment of the surface 11a to be processed is performed.

  Next, when the surface treatment of the surface 11a to be processed of the optical element molding die base material 11 located in the region V is completed, the vacuum chamber 2 is opened to the atmosphere and the optical element molding die base material after processing from the support 12 is processed. 11 is taken out. In this way, as shown in FIG. 3, the optical element mold 23 in which the film body 23A is formed is manufactured.

  According to this plasma processing apparatus 1, microscopic surface defects due to droplets and scattered particles on the surface of the optical element molding base material 11 are suitably suppressed, high density, high adhesion strength, and extremely few defects. A surface can be obtained and processed with high accuracy and reliability.

  Further, in this way, according to the optical element molding die 23 whose surface 11a to be processed is surface-treated, microscopic surface defects due to droplets and scattered particles are suitably suppressed in the film body 23A. Accurate and highly durable molding can be performed.

Further, in the same manner as described above, by changing the shape of the surface 11a to be processed of the optical element molding die base material 11, optical element molding dies corresponding to various shapes can be manufactured.
For example, as shown in FIG. 4, an optical element molding die 24 in which the processing surface 11a is a concave surface and a film body 24A is formed on the processing surface 11a by the plasma processing apparatus 1 can be manufactured.
Using these optical element molds 23 and 24, a lens 26 having a concave second lens surface 26a and a convex first lens surface 26b can be molded.
That is, the optical element molding dies 23 and 24 are positioned in the radial direction by the cylindrical mold member 25 in a state where the processing target surfaces 11a on which the film bodies 23A and 24A are formed are opposed to each other. A molding space surrounded by each processing surface 11a on which 24A is formed and the inner peripheral surface of the mold member 25 is formed. Then, a heated glass material is disposed in the molding space, the optical element molding dies 23 and 24 are pressed in the axial direction, the glass material is pressed, the mold surface shape is transferred, and the lens is removed. 26 can be molded.

[Second Embodiment]
Next, a plasma processing apparatus according to the second embodiment of the present invention will be described.
FIG. 5 is a schematic partial sectional view in front view showing a schematic configuration of a plasma processing apparatus according to the second embodiment of the present invention. FIG. 6A is a schematic left side view (view E in FIG. 5) showing a schematic configuration of the anode electrode used in the plasma processing apparatus according to the second embodiment of the present invention. FIG.6 (b) is FF sectional drawing in Fig.5 (a).

  The plasma processing apparatus 1A of the present embodiment includes a shielding cover 30 (shielding portion) instead of the shielding plate 20 of the plasma processing apparatus 1 of the first embodiment. Hereinafter, a description will be given centering on differences from the first embodiment.

As shown in FIGS. 6A and 6B, the shielding cover 30 is a member made of a substantially cylindrical nonmagnetic material having an inner diameter slightly larger than the outer diameter of the plasma emitting unit 10. Are arranged so as to cover the outer peripheral side of the plasma emitting part 10 in a state of being substantially coaxial with the central axis O of the target 6.
The front end surface 30e on the front end side of the plasma emitting unit 10 in the shielding cover 30 is disposed at substantially the same position as or slightly in front of the front end of the plasma emitting unit 10.
And at the front-end | tip part of the shielding cover 30, the U-shaped notch part which consists of notch surface 30a, 30b, 30c on the side surface on the opposite side to the optical element shaping | molding die base material 11 arrange | positioned in the area | region V is carried out. A formed opening 30d is provided. Here, the notch surface 30a is a cut surface extending along the axial direction of the shielding cover 30 from the front end surface 30e, and the notch surface 30c is opposed to the notch surface 30a while being spaced apart in the circumferential direction of the shielding cover 30. It is a cut surface. Moreover, the notch surface 30b is a cut surface connected to the edge part on the opposite side to the front end surface 30e of the notch surfaces 30a and 30c.
The position in the circumferential direction of the opening 30d is a position where the opening 7d of the anode electrode 7 can face the opening 30d when viewed from the outside in the radial direction.
Further, the position along the axial direction of the notch surface 30 b is preferably closer to the base end side than the tip end 6 a of the target 6, and more preferably closer to the base end side than the trigger electrode 5. Further, it may be approximately the same as the axial length of the opening 7d.

  With such a configuration, the shielding cover 30 covers at least the outer peripheral side of the rotating electrode portion 7A between the target 6 and the processing target surface 11a of the optical element molding die base material 11 disposed in the region V. Is provided. For this reason, the shielding cover 30 is provided between the object to be processed and the anode electrode, and constitutes a shielding part that shields a path that goes straight from the target toward the object to be processed.

According to such a plasma processing apparatus 1A, as in the plasma processing apparatus 1 of the first embodiment, the surface 11a to be processed of the optical element molding base material 11 disposed in the region V is surface-treated. be able to.
At that time, among the scattered particles 19 scattered from the surface of the target 6, the scattered particles 19 that pass upward through the gaps between the arcuate conductors 7 a of the circular electrode portion 7 </ b> A are separated by the shielding cover 30. Since the straight path is shielded, it collides with the inner peripheral surface of the shielding cover 30 and is reflected or attached to the inner peripheral surface.
The scattered granular material 19 reflected by the inner peripheral surface of the shielding cover 30 is finally attached to any of the shielding covers 30 by repeating reflection or the like, or passes through the opening 30d to form an optical element. It scatters below the vacuum chamber 2 on the opposite side to the mold base 11.
For this reason, it can prevent that the scattering granular material 19 adheres to the to-be-processed surface 11a to surface-treat.
The shielding cover 30 is arranged close to the outer peripheral side of the anode electrode 7, so that the scattered granular material 19 can be formed even if the shielding area is reduced compared to the case where the shielding portion is provided at a position further away from the anode electrode 7. It can be reliably shielded.

[Third Embodiment]
Next, a plasma processing apparatus according to a third embodiment of the present invention will be described.
FIG. 7 is a schematic partial sectional view in front view showing a schematic configuration of a plasma processing apparatus according to the third embodiment of the present invention. FIG. 8 is a schematic cross-sectional view of an optical element molding die manufactured by using the plasma processing apparatus according to the third embodiment of the present invention.

  As shown in FIG. 7, the plasma processing apparatus 1 </ b> B of the present embodiment is connected to the support base 12 via the feedthrough 36 and connected to the plasma processing apparatus 1 of the first embodiment. 11, a bias power supply unit 37 for applying a negative bias voltage is added. Hereinafter, a description will be given centering on differences from the first embodiment.

  The bias power source unit 37 detects that arc discharge has occurred between the target 6 and the anode electrode 7 by a control means such as a computer (not shown), and the optical element molding die base material 11 supported by the support base 12. A negative bias voltage is applied to.

  According to such a plasma processing apparatus 1B, similarly to the plasma processing apparatus 1 of the first embodiment, an arc discharge is caused between the target 6 and the anode electrode 7, and the plasma 8 is generated by the plasma emitting unit 10. generate. Each time the plasma 8 is generated, the bias power supply unit 37 applies a negative negative bias voltage having a magnitude of, for example, about 10 kV to the optical element molding base material 11. Here, for example, the bias power supply pulse width is 12 μsec, the interval is 25 μsec, and the number of repetitions is 100 times.

At this time, since the plasma ions are positively charged, the particles of the plasma 8 are accelerated in the vicinity of the surface 11a to be processed by such a negative high voltage pulsed bias voltage, and the optical element molding die It collides with the base material 11 and is driven into the inside of the surface 11a to be processed.
In this way, platinum ions are easily extracted from the plasma 8 and injected into the optical element molding die base material 11 from the surface 11a to be processed.
At this time, by gradually changing the magnitude of the bias voltage, the concentration of platinum injected into the optical element molding base material 11 can be gradually changed.
In this way, as shown in FIG. 6, the graded layer 38 having the graded composition of platinum is formed by injecting platinum whose concentration gradually changes under the surface 11 a to be treated.

When the inclined layer 38 is formed, the magnitude of the negative bias voltage by the bias power supply unit 37 is reduced to about 300 V, for example, and the arc discharge of the plasma emitting unit 10 is further repeated.
As a result, platinum ions in the plasma 8 transported on the surface 11a to be processed sequentially adhere to the surface 11a to be processed, and a protective film 40 made of a platinum alloy is formed on the inclined layer 38.
In this way, the optical element molding die 41 having the inclined layer 38 and the protective film 40 on the surface is manufactured.
Here, the inclined layer 38 constitutes an intermediate layer that improves the adhesion strength between the optical element molding die base material 11 and the protective film 40.

  According to the plasma processing apparatus 1B, by applying a negative bias voltage to the optical element molding die base material 11 by the bias power supply unit 37, clean plasma 8 particles that do not include the scattered granular material 19 are formed for optical element molding. It can be injected not only into the surface of the mold base material 11 but also into the inside thereof.

  Further, by controlling the bias power supply unit 37 to change the magnitude of the negative bias voltage applied to the optical element molding base material 11, the protection tightly adhered to the surface via the inclined layer 38 is achieved. The film 40 can be formed.

The technical scope of the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above description, the shape of the target 6 is a cylindrical bar, but it may be a pellet, a line, or a cylinder. The material of the target 6 is not limited to platinum but may be noble metals such as gold, iridium, ruthenium, rhodium and palladium, or carbon.

In the above description, the example in which a plurality of arcuate conductors 7a are employed as the circular electrode portion has been described. However, the shape of the plurality of conductors is an arcuate shape as long as the arcuate shape has an opening on one side. It is not limited to.
For example, the shape may be an ellipse, a substantially arc shape slightly shifted from the arc, or a shape obtained by bending the wire into a polygonal shape.
In addition, the length of the substantially arched circumferential direction that determines the range in which the conductor surrounds the target can also be appropriately dimensioned. For example, in terms of an arc shape, the central angle is not limited to a super arc shape (C shape) larger than 180 degrees, and may be a semicircular arc shape or a sub arc shape with a central angle smaller than 180 degrees.
The size of the central angle is preferably 10 degrees or more and 120 degrees or less.
Further, the substantially arcuate circulation direction is not limited to a direction orthogonal to the center axis of the target, and may be an oblique direction intersecting the center axis of the target.

  In the above description, the example in which the central axis of the substantially arched shape of the circular electrode portion is arranged coaxially with the central axis of the target has been described. However, the magnetic field generated by the current flowing through the circular electrode portion is substantially arched. Therefore, the central axis of the substantially arcuate shape may be deviated from the central axis of the target. Even if these central axes are deviated from each other, the plasma is transported in the direction along the central axis of the target and emitted from the tip of the target.

  Further, in the above description, the trigger electrode 5 is arranged around the target 6 via the insulator 3. However, the trigger electrode 5 may suffice if it can cause a trigger discharge between the target 6 and the insulator. Air may be used. For example, the trigger electrode 5 may be disposed with a gap of 1 mm or less between the target 6 and the space discharge.

In the above description, the deflecting unit 13 includes the magnet 17 and the L-shaped yoke 18 and deflects the transport path of the plasma 8 by the magnetic field. However, the L-shaped opening angle is an angle other than 90 degrees. But you can. The magnet 17 may be an electromagnet.
The deflecting unit may generate an electric field instead of a magnetic field and deflect the plasma path by the electromagnetic force.

  In the description of the third embodiment, an example in which the bias power supply unit applies a negative bias voltage in a pulsed manner has been described. However, conditions such as a waveform of the bias voltage can be freely set according to the purpose of the surface treatment. For example, a waveform obtained by alternately mixing a positive voltage and a negative voltage, or a steady voltage as a positive low voltage may reduce the speed of plasma ions attracted to the object to be processed.

  In the above description, the negative connection terminals 16b and 15b have been described as examples in which the connection terminals 16b and 15b are separately connected to the target 6 as base electrodes. However, the connection terminals 16b and 15b are connected by a single connection line. May be. Further, the negative connection terminals 16b and 15b may be connected to the target 6 via a conductive member serving as a base electrode. The connection terminals 16b and 15b may be welded portions formed by welding.

In the above description, the center axis of the surface to be processed of the object to be processed is arranged in a positional relationship orthogonal to the center axis of the target, and the plasma emitted from the plasma emission part is deflected in a direction orthogonal to the plasma emission direction. Explained in the case of an example.
The plasma transport direction in the vicinity of the surface to be processed is preferably a direction along the center axis of the surface to be processed, but the deflection angle by the deflecting unit and the angle between the center axis of the surface to be processed and the plasma emission direction are , Not limited to 90 degrees, may be in a positional relationship that intersects at an angle different from 90 degrees.

In the above description, an example in which one optical element molding base material 11 is disposed on the support base 12 has been described. However, the support base 12 includes a plurality of optical element molding base materials 11. The optical element molding die base material 11 can be rotated about the shaft 21 and the optical element molding die base material 11 is moved back and forth on the region V. May be processed.
In this case, only the transport path of the plasma 8 below the region V is opened in the shielding plate 20 so that the scattered granular material 19 does not reach the optical element molding die base 11 arranged outside the region V. It is preferable to use a perforated plate.

In the above description, the support base 12 is described as an example in which the support base 12 is fixed to the vacuum chamber 2. However, the support base 12 is supported to be swingable in two axial directions (horizontal directions) orthogonal to the shaft 21. May be.
In this case, since the optical element molding die base material 11 is oscillated as the support base 12 is oscillated, the entire surface 11a to be processed can be obtained even when the cross-sectional area of the transport path of the plasma 8 is reduced. A uniform film body 23A can be formed.
For example, when the diameter of the surface 11a to be processed of the optical element molding base material 11 is 20 mm, the distribution of the magnetic lines of force of the deflecting unit 13 is adjusted so that the diameter of the transport range of the plasma 8 on the surface 11a is 10 mm. And about half the diameter of the surface 11a to be processed.
And while the plasma 8 reaches | attains the to-be-processed surface 11a, a rocking | fluctuation mechanism is driven and the support stand 12 is biaxially swung within a horizontal surface. Thereby, while the plasma 8 is transported, the plasma 8 relatively swings and moves on the processing surface 11a, and the flow of the plasma 8 is scanned on the processing surface 11a. Even if there is a density distribution, the average is obtained on the surface 11a to be processed and reaches the entire surface uniformly.

  Moreover, all the components of each of the embodiments described above can be implemented in appropriate combination within the scope of the technical idea of the present invention.

DESCRIPTION OF SYMBOLS 1, 1A, 1B Plasma processing apparatus 2 Vacuum chamber 3 Insulator 5 Trigger electrode 6 Target 7 Anode electrode 7A Circulating electrode part 7B Wiring part 7a Arc-shaped conductor (conductor)
7d Opening 8 Plasma 10 Plasma emitting part 11 Optical element molding die base material (object to be processed)
11a Surface to be processed (surface of object to be processed)
12 Support stand 13 Deflection part 15 Trigger power supply 16 Arc power supply 19 Scattering granular material 20 Shielding plate (shielding part)
23, 24, 41 Optical element molding dies 23A, 24A Film body 26 Lens 30 Shielding cover (shielding part)
37 bias power supply unit 38 inclined layer 40 protective layer _{I A} arc current _{S A} arc spot C center axis O center axis (the center axis of the target)
V region

Claims (7)

A plasma having a trigger electrode for generating a trigger discharge with an axial target and an anode electrode for inducing an arc discharge with the target, and containing ions of the target generated by the arc discharge A plasma emission part that emits toward the tip of
A deflecting unit for transporting the plasma to the surface of the object to be processed by deflecting the plasma emitted from the plasma emitting unit in a direction crossing the axial direction of the target;
A plasma processing apparatus provided with a shielding part that is provided between the object to be processed and the anode electrode and shields a path that goes straight from the surface of the target toward the object to be processed;
The anode electrode of the plasma emission part is
A plurality of substantially arch-shaped conductors having openings on one side are arranged so as to circulate around the target in the axial direction, and the plurality of conductors are disposed on the opposite side of the target object with the target interposed therebetween. A circular electrode part in which each opening of the body is arranged;
A plasma processing apparatus comprising: a wiring portion that supplies current to the circumferential electrode portion. The circular electrode part is
The plasma processing apparatus according to claim 1, wherein a central axis of the substantially arched shape is disposed substantially coaxially with a central axis of the target.   The plasma processing apparatus according to claim 1, wherein the substantially arched shape of the circular electrode portion is an arc shape.   The plasma processing apparatus according to claim 1, further comprising a bias power supply unit that applies a bias voltage to the object to be processed.   A method for manufacturing an optical element molding die, wherein the surface treatment is performed on the surface of a mold base material, which is an object to be processed, using the plasma processing apparatus according to claim 1.   The plasma processing apparatus according to claim 4 is used to transport the plasma generated by the plasma processing apparatus to the surface of a mold base material that is a processing target and to apply a bias voltage to the processing target. To implant or attach ions of the target contained in the plasma, or to implant and attach the target ions.   7. The target ions contained in the plasma are attached to the surface of the mold base material after being implanted by changing the bias voltage applied to the object to be processed. The manufacturing method of the optical element shaping die of description.

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