JP2007246974A - Coating method for extra-long shaft body and coating apparatus for extra-long shaft body - Google Patents

Abstract

An object of the present invention is to make it possible to satisfactorily perform sputtering of a target material on an inner peripheral surface or an outer peripheral surface of an extra-fine tube or a wire-like long shaft.
In a vacuum vessel, a first ultralong shaft body and a second ultrathin shaft body are formed of ultrathin tubes, one of which is a sputter target along the direction of gravity and the other is a sputter target. 5 is placed on the same axis. While introducing the plasma source gas, sputtering is performed by generating harmonic ECR plasma by introducing a microwave and applying a mirror magnetic field. At this time, since the very long shafts are arranged in the direction of gravity, fluctuations in the distance between the very long shafts in the axial direction due to expansion due to thermal expansion and thinning due to sputtering can be avoided.
[Selection] Figure 1

Description

  TECHNICAL FIELD The present invention relates to a coating method for a very long shaft body and a coating apparatus for a very long shaft body.

For example, dialysis filters, tubes, catheters such as artificial blood vessels in the urinary system, respiratory system, digestive system, circulatory system, etc., related to medical care, reduce the patient's pain, so that the so-called ultrathin tubes The demand is growing.
In addition, the tubes and catheters used in medical relations, etc. have bioalloys, Au, Ag on the inner peripheral surface thereof for the purpose of chemical stabilization and alteration prevention, blood coagulation prevention, blood circulation improvement, and the like. It is desired to form a film of various materials such as metals, plastics, and the like in a strong, uniform and uniform thickness.
However, a coating method for coating a target material on the inner peripheral surface of an ultrathin tube having an inner diameter of 1 mm or less has not been established yet.

Conventionally, there is a dry coating method as a coating method for forming a film on a normal peripheral surface of a tubular body. This is due to high pressure plasma CVD (Chemical Vapor Deposition) or plasma PVD (Physical Vapor Deposition), but it is difficult to generate plasma in a narrow tube under low pressure conditions. It cannot be applied to the medical thin tubes described above.
For this reason, the mainstream for film formation on thin tubes is wet coating. However, according to this method, there is not only a fatal problem that the adhesion of the coating is weak, but also the degree of freedom in selecting the coating material is small, and even in this case, it cannot be applied to the ultrathin tube.

  On the other hand, the present inventors firstly generated plasma by ECR (Electron Cyclotron Resonance) in, for example, medical tubules, and sputtered various materials on the inner peripheral surfaces of these tubules. A coating method and a coating apparatus for forming a film have been proposed (see, for example, Patent Document 1 and Patent Document 2).

  In this sputtering method using plasma generated by ECR, a target of a wire-like sputtering material is placed concentrically in a target tube for film formation, that is, a film is formed, and a plasma source is placed in the space between the two. ECR is generated by introduction of gas, introduction of microwave, and application of magnetic field to generate plasma, and the target material is knocked out by bombarding the target on the cathode side to form a film. Sputtering film formation is performed on the inner peripheral surface of the tube.

However, even by this ECR method, it is extremely difficult or impossible to perform sputtering of various materials on the inner peripheral surface of the above-described ultrathin tube of 1 mm or less.
This is because the electron trajectory, that is, the electron confinement cannot be sufficiently narrowed by the above-described ECR method, so that the target disposed on the central axis of the narrow microtubule and the inner peripheral surface of the microtubule Electrons that should contribute to plasma generation when electrons collide with atoms in the plasma source gas at a narrow interval (narrow gap) between them collide with the walls of the space and disappear, and are accelerated by a strong electric field. This is because the probability of collision with the plasma source gas is reduced by this, so that plasma generation in the ultrathin tube becomes impossible.
JP-A-7-252663 JP-A-8-296038

The present inventors previously proposed in Japanese Patent Application No. 2005-121592 an excellent film quality coating method and coating apparatus by satisfactorily sputtering various materials in an ultrathin tube.
The present invention provides a more stable and high-quality sputtered film, for example, sputtering of a target material on the inner or outer peripheral surface of a microtubule or wire-shaped long shaft whose length is in the order of meters. The present invention provides a coating method for an ultra-thin shaft body and a coating apparatus for the ultra-long shaft body that can be performed.

  According to the coating method of the very long shaft body according to the present invention, the first and second very long shaft bodies are formed on the same axis in the vacuum region along the direction of gravity. A required gap is arranged between the shaft bodies, and in this state, either one of the first and second very long shaft bodies is a sputter target, the other is a sputter target, and the sputter target side is A negative voltage is applied, a plasma source gas is introduced into the gap, and a harmonic ECR (Electron Cyclotron Resonance) plasma is generated by introducing a microwave and applying a mirror magnetic field to generate the first very long axis. A coating of the sputter target material is performed on the inner peripheral surface of the body or the outer peripheral surface of the second extra long shaft body.

The present invention is also directed to the coating method on the ultra-long and thin shaft body, wherein the mirror magnetic field is moved in the axial direction and the main plasma generation unit is moved in the axial direction.
Similarly, in the coating method for the above-mentioned ultra-thin shaft, a negative voltage pulse bias is repeatedly applied to the sputter target side.

  According to the present invention, there is provided a coating apparatus for an extremely long shaft body, a vacuum container, a mirror magnetic field generator disposed on the outer periphery of the vacuum container, a plasma source gas supply source, a microwave generator, and the vacuum container. A very long shaft body in which a first ultra long shaft body and a second ultra long shaft body by a micro tube are arranged coaxially along the direction of gravity and holding a required gap between both the long shaft bodies. And a power supply unit for applying a required voltage between the first and second elongated shaft bodies, and one of the first and second elongated shaft bodies is a sputtering target. And applying a voltage with the other side to be sputtered and the sputter target side being a negative side, introducing a plasma source gas from the plasma source gas source into the gap, and the microwave generator and the mirror magnetic field Harmonic ECR (Electron Cyclotron Resonance) plasma is generated by introducing a microwave and applying a mirror magnetic field by a raw device, and is generated on the inner peripheral surface of the first ultrathin shaft body or the outer peripheral surface of the second ultrathin shaft body. The sputter target material is coated.

Further, the present invention is a coating apparatus for the above-mentioned extremely long and thin shaft body, in which the required tension in the gravity direction along the axial direction is arranged on the arrangement portion of the above-mentioned extremely long and slender shaft body and on the second very long and narrow shaft body. It is characterized in that a tension applying means for applying is arranged.
The present invention is also directed to a coating apparatus for the above-mentioned ultra-thin shaft body, wherein the magnetic field generator is arranged on the outer circumference of the vacuum vessel along the axial direction of the first and second ultra-thin shaft bodies. A plurality of electromagnetic coils are arranged, and the main plasma generation position is moved along the axial directions of the first and second very long shaft bodies by switching energization or energization amount to the plurality of electromagnetic coils. It is characterized by doing so.
The present invention is also directed to a coating apparatus for the ultrathin shaft body, wherein the power supply unit for applying a required voltage between the ultrathin tube and the sputter target includes a negative voltage pulse on the sputter target side. The power supply unit applies a bias.

As described above, in the coating method and apparatus according to the present invention, the first ultralong shaft body and the second ultrathin shaft body in which either one is used as a sputter target and the other is used as a sputter target ultrafine tube. Is placed on the same axis with the required gap between the two elongated bodies, and a voltage with the sputter target side as the negative side is applied, and harmonic (harmonic) ECR (Electron Cyclotron Resonance) plasma is used. Sputtering is performed.
In this way, harmonic ECR plasma, that is, second harmonic and third harmonic plasma, for example, is generated and sputtered using this, so that plasma generation at low pressure is evident as will be described later. In addition, it has an effect that electrons can be well confined.
Therefore, plasma can be generated satisfactorily in a narrow space, and a high-quality coating can be formed by sputtering on the inner wall surface of a microtubule, for example, a microtubule having an inner diameter of 1 mm or less. Is.

Further, as described above, by applying a negative voltage pulse bias repeatedly to the target side, the ion sheath is reduced, that is, the plasma is recovered during the off time, so that sputtering can be performed satisfactorily. It is something that can be done.
This is because when the negative DC voltage is continuously applied to the target side, the ion sheath expands, thereby the plasma disappears, the ion current density to the target decreases, and the phenomenon in which sputtering decreases or stops, By adopting a method in which a negative repetitive pulse bias voltage is applied, the ion sheath is reduced when the negative voltage is turned off, whereby the plasma can be recovered.

As described above, in the present invention, by utilizing a unique resonance phenomenon called harmonic ECR plasma, discharge at a low pressure and a short gap is possible, and on the inner or outer peripheral surface of the very long shaft body, High quality film formation can be performed efficiently. However, in this case, for example, when sputtering is performed on the inner peripheral surface of a metric order ultrathin tube, there may be a problem in performing uniform and homogeneous sputtering over the entire length of the ultrathin shaft body. is there.
This is because the distance between the first and second elongated shafts becomes narrower, and the plasma generation region (gap length) needs to be held more stably and accurately. Then, the sputter target is likely to be bent due to thermal expansion due to a temperature rise during the sputtering operation or thinning of the sputter target due to the progress of sputtering, and the distance between the ultrafine sputter target and the inner peripheral surface of the ultrafine tube. May become non-uniform or unstable, and the film formation may be non-uniform or unstable.
However, according to the above-described method and apparatus of the present invention, by arranging the microtubules along the direction of gravity, the expansion and contraction is mainly performed in the direction of gravity, that is, in the axial direction. The variation in the distance between the long axis bodies is effectively improved.

  Further, in the present invention, sputtering of the target material is performed by generating plasma by magnetic resonance, but this magnetic resonance has a mode in which plasma is generated by a mirror magnetic field, so that electron confinement in the tube axis direction is good. Thus, the ion generation rate can be increased, high density ions can be obtained at low pressure, and the sputtering efficiency can be increased.

  In addition, the resonance condition of the magnetic resonance changes between the microwave introduction side and the position away from the microwave, and as described above, the difference becomes significant as the axial length increases. In the present invention, by moving the mirror magnetic field in the axial direction and controlling the energization, optimal plasma generation can be controlled in each part, and the above-described sputter target and the inner peripheral surface of the microtubule can be controlled. In combination with the uniformity and stabilization of the distance, the uniformity and controllability of the film formation can be improved.

  Further, in the present invention, the movement of the mirror magnetic field is configured such that a plurality of magnetic field generating coils are arranged in the axial direction irrespective of the mechanical movement of the apparatus, and the plurality of coils are selectively energized, and the energization is performed. Since the magnetic field distribution in the axial direction of the mirror magnetic field is obtained by this control, the apparatus can be simplified and accuracy and controllability can be improved as compared with the case where the mirror magnetic field generator itself is moved.

Although the embodiment of the coating method and the coating apparatus for the ultra-thin shaft body according to the present invention is illustrated, the present invention is not limited to this embodiment.
1A and 1B are a longitudinal sectional view of a main part of a coating apparatus and a sectional view taken along line BB for explaining the basic operation of the coating apparatus according to the present invention for performing the coating method according to the present invention.

  In the embodiment of the apparatus of the present invention for carrying out the coating method according to the present invention, the first ultra-long elongated shaft body 4 made of ultra-thin tubes along the direction of gravity in the vacuum vessel 1 constituting the vacuum space, and the first Within one ultra-thin shaft body 4, a second ultra-thin shaft body 5 made of a micro tube or wire having an outer diameter smaller than the inner diameter of the first ultra-thin shaft body 4 is arranged on the same axis. An arrangement unit is configured. A required gap G is formed between the first and second elongated shafts 4 and 5.

Either one of the first and second very long shafts is a sputter target, and the other is a sputter target.
In this embodiment, the case where the first ultra-long elongate shaft body 4 is an object to be sputtered is illustrated.
Then, a voltage having the second very long axis on the sputter target side as a negative side is applied, a plasma source gas is introduced into the gap G, and, for example, by introducing a microwave and applying a mirror magnetic field, second harmonics are applied. Harmonic ECR plasma is generated.

That is, in the mirror magnetic field,
he (= ωce / νe)> 1 (1)
And ωce / ω = 0.5 (2)
Where he is the electron Hall parameter
ωce is the electron cyclotron frequency
νe is the average collision time of electrons
ω performs plasma generation under microwave frequency conditions.
In this way, the second harmonic ECR is generated by forming a condition that satisfies the expressions (1) and (2).
In this case, since he is proportional to the ratio B / P between the magnetic flux density B and the atmospheric pressure P, he can be selected by selecting the magnetic flux density B and the atmospheric pressure P.

  Then, the second harmonic plasma generated in the mirror magnetic field over the entire length of the region requiring the uniform sputter film formation in the first ultrathin shaft 4 by the ultrathin tube is used as the mirror magnetic field. Move by moving.

In this coating apparatus, a cylindrical outer electrode 2 and a center electrode 3 are arranged on the same axis in the vacuum vessel 1 along the direction of gravity indicated by an arrow a in FIG. 1A.
In the outer electrode 2, the first ultrathin shaft 4 made of the above-described ultrathin tube is disposed.
In the center electrode 3, for example, a second very long shaft 5 serving as a sputtering target is disposed. When the second very long shaft 5 is a conductive material, the second very long shaft 5 is electrically and mechanically connected to the tip of the center electrode 3, or the second The center electrode 3 can be constituted by the two very long and thin shaft bodies 5 themselves.

Further, when the target material is insulative, a sputter target material is deposited on the outer periphery of the conductive electrode core of the center electrode 3 or the second extra long shaft body 5, or a cylindrical sputter target is disposed. It can be configured.
In any case, the total length of the region where the sputter target component of the second very long shaft body 5 requires at least uniform sputter deposition of the first very long shaft body 4 of the sputtered body, for example, the first It arrange | positions so that it may oppose over the full length of the 1 ultra-thin shaft 4.

A tension applying means 50 such as a weight or a spring for applying a required tension is connected to the lower end of the second very long shaft body 5 constituting the sputter target along the long axis direction, that is, in the gravity direction a.
Further, on the outer periphery of the vacuum vessel 1, a plurality of electromagnetic coils C1, C2, C3... That form a mirror magnetic field are coaxially arranged with the first and second elongated shaft bodies 4 and 5, and the axial center thereof. Arrange sequentially in the direction.

  When coating the inner peripheral surface of the first very long shaft body 4 by the ultrathin tube with this coating apparatus, the inside of the vacuum vessel 1 is evacuated, and the space between the first and second very long shaft bodies 4 and 5 is reduced. The space in the gap G is once evacuated to a vacuum space, and then a plasma gas source is introduced at a required low pressure.

Then, a negative voltage pulse bias voltage is repeatedly applied between the first and second very long shaft bodies 4 and 5 on the sputter target side, in this example, on the second very long shaft body 5 side.
In addition, a microwave of 2.45 GHz, for example, is supplied to the center electrode 3 or the second very long shaft 5 through a matching circuit in a coaxial mode (TEM mode).
On the other hand, a required mirror magnetic field is applied.
This mirror magnetic field can be formed, for example, by pairing adjacent pairs of coils C1 and C2 and passing a current in the same direction through these pairs of coils. In this case, in the pair of coils C1 and C2, a magnetic field peak, that is, a mirror is formed, and a magnetic field valley is formed at an intermediate portion thereof, thereby confining electrons. Alternatively, three coils C1, C2, and C3 are combined to form a mirror magnetic field by energizing coils C1 and C3 in the same direction, and the distribution of the mirror magnetic field is controlled by controlling the energization of the intermediate coil C2. You can also.

In this manner, the above-described second harmonic plasma can be generated in the mirror magnetic field under the required conditions such as the microwave power and the strength of the mirror magnetic field, and the electrons are confined in the mirror magnetic field. Thus, ions can be generated here with high efficiency.
Thereby, as schematically shown in FIGS. 1A and 1B, the ions 7 generated by the plasma generation by the second harmonic ECR are attracted to the second very long shaft body 5 of the target, and thereby the target. , The target atoms 8 are knocked out, and the target material is deposited on the inner peripheral surface of the first ultralong shaft body 4 by the ultrathin tube to form a film.
In this manner, the target material is sputtered from the sputter target of the second ultralong shaft body 5 on the inner peripheral surface of the ultralong shaft body 4 by the ultrathin tube, and the target material is coated.

  In the above-described coating, the above-described two or three electromagnetic coils C1, C2, C3,. By performing the required energization for the set to generate the main plasma, and sequentially switching the energization to the adjacent coils, the main plasma is moved in the axial direction, and the energization amount is controlled as necessary. By changing the plasma density with respect to the axial direction of the ultrathin tube, it is possible to compensate for the difference in the film forming conditions at each part and perform uniform and uniform film formation over the entire region.

  In the configuration shown in FIG. 1, a state is shown in which the first ultrathin shaft 4 of the ultrathin tube is disposed in close contact with the outer electrode 2, but for example, with respect to the outer electrode 2 having a constant inner diameter. When forming a film on the first elongate shaft body 4 made of an ultrathin tube having a smaller diameter than this, an outer electrode can be formed without interfering with the electric field strength by disposing a dielectric, for example, a ceramic therebetween. 2 can be made compatible with microtubules 4 having different outer diameters.

The 2nd Harmonic (second harmonic) ECR has been proposed in the Japanese Patent Application No. 2005-121592 filed by the present applicant.
The ECR (ωce / ω = 1) in Patent Documents 1 and 2 and the 2nd Harmonic ECR (ωce / ω = 0.5) in the present invention are based on plasma generation by high-frequency discharge in a magnetic field application. Is dependent on the discharge start condition, the electron trapping condition, and the electron ionization energy condition, but the above-described ECR has the effect of reducing the discharge start electric field. In particular, in the harmonic ECR, a resonance trapping effect by electron confinement can be obtained, thereby enabling plasma formation with a narrow gap length, and by reducing the atmospheric pressure, good film quality and deposition strength can be obtained. High coating can be performed.
Specifically, for example, plasma is generated at a pressure that is four orders of magnitude lower than that of normal plasma generation in a PDP (Plasma Display Panel).

  2A and 2B are diagrams showing electron trajectories in the case of 2nd Harmonic ECR (ωce / ω = 0.5) and ECR (ωce / ω = 1). FIG. 2A and FIG. 2B are compared. As is apparent from the above, when the 2nd Harmonic ECR is used, electrons are strongly confined, so that electrons can effectively collide with atoms of the plasma source gas and ionize in a narrow gap. Recognize.

  FIG. 3 is a diagram showing a magnetic field distribution when the adjacent electromagnetic coil is energized in the same direction in a model in which a ceramic is disposed between the center electrode and the outer electrode. In this case, the “0” point on the position of the horizontal axis is the center between the pair of electromagnetic coils, and a magnetic field valley is formed at this center, so that the electrons are confined here. is there.

  Therefore, according to the present invention, the electrons and confinement by the harmonic ECR and the electron confinement by the mirror magnetic field combine to increase the electron density, increase the ion concentration, and increase the deposition rate by sputtering.

FIG. 4 is a schematic configuration diagram of an embodiment of a coating apparatus according to the present invention.
This coating apparatus has, for example, a cylindrical vacuum vessel 1, and in the vacuum vessel 1, for example, an arrangement portion of an ultrathin tube that arranges a first ultralong shaft body 4 by an ultrathin tube that performs coating on an inner peripheral surface, for example. And the arrangement | positioning part which arrange | positions the 2nd very elongate shaft body 5 which comprises a sputter | spatter target on the center axis | shaft is provided.
The vacuum vessel 1 is connected to an exhaust device 9 for exhausting, for example, a turbo molecular pump 9M and a rotary pump 9R.
Furthermore, a plasma source gas supply source 10 that supplies the above-described plasma source gas is connected to the vacuum vessel 1 via a mass flow controller 11.

Further, the mirror magnetic field generator 12 in which the plurality of electromagnetic coils C1, C2, C3,.
An exciting current source 13 for the electromagnetic coils C (C1, C2, C3... Cn) of the magnetic field generator 12 is provided.
As described above, the exciting current source 13 moves the mirror magnetic field along the axial direction of the vacuum vessel 1 by moving the mirror magnetic field from the required position, for example, from one end to the other end and switching the main plasma generation position. It is made to let you.

Further, a microwave generator 14, its power monitor 15, and a stabilization tuner 16 are provided, and a TEM wave, for example, is applied to the second very long shaft 5 that constitutes the center electrode 3 or the target through the coaxial cable 17. 2.45 GHz microwave is supplied.
Further, a power supply unit 6 for applying the above-described required voltage between the outer electrode 2 and the center electrode 3, that is, between the first and second elongated shaft bodies 4 and 5, for example, the aforementioned pulse bias. A source is provided.

  By the coating apparatus having this configuration, the sputter target material of the second extra elongated shaft body 5 is sputtered on the inner peripheral surface of the first extra elongated shaft body 4 by the ultrafine tube, and coating with the target sputter target material is performed. A layer is formed. That is, a plasma source gas is introduced into the gap G between the first and second very long shafts 4 and 5, and a harmonic ECR (Electron Cyclotron Resonance) plasma is generated by introducing the microwave and applying a mirror magnetic field as described above. The sputter target material is coated on the inner peripheral surface of the ultrathin tube of the first ultrathin shaft 4 by sputtering.

  FIG. 5 is a flowchart showing the procedure. That is, the inside of the vacuum vessel 1 is evacuated by the exhaust device 9, a required amount of plasma source gas is supplied from the supply source 10, the power source of the microwave generator 14 is turned on, and the power monitor 15 is used to adjust the power power. Introduce waves. Then, the mirror magnetic field generator 20 is operated, and a pulse bias is applied from the power supply unit 6. Then, the coils C1 to Cn of the mirror magnetic field generator 20 are sequentially operated, and the sputter film formation is performed on the inner surface of the first very long shaft body 4 using a very thin tube.

  When the microwave is incident from the strong magnetic field side, the microwave power can be efficiently absorbed by the plasma when generating the plasma. Furthermore, by using a microwave power supply that can supply power of several watts with high accuracy, the power can be set with high accuracy, and unnecessary heat irradiation to the internal electrodes and ultrathin tubes can be prevented. It is possible to effectively avoid damage to the ultrathin tube 4 due to heat and deformation of the internal electrode due to heat.

  FIG. 6 shows respective ions when the bias voltage Vb is selected to be −100 V, −200 V, and −300 V when sputtering is performed by forming a harmonic ECR (Electron Cyclotron Resonance) plasma by the mirror magnetic field according to the present invention. The measurement result of current density is shown.

7 and 8 show the measurement results of the ion current density with respect to the same bias voltage when a uniform magnetic field independent of the mirror magnetic field is used.
6 and 7 show that when sputtering is performed on a Pyrex glass tube, Ar is used as an introduction gas, the inside of the vacuum vessel is 70 mTorr, the microwave input power is 30 W, the magnetic field strength is 438 gauss at the center of the coil, the target FIG. 8 shows a case where the diameter is 2 mm, the gap length (interval between the first and second extra elongated shafts 4 and 5) is 1.8 mm, the pulse frequency is 2 kHz, and the pulse width is 35 μm. This is a case where the length is a large interval of 3.5 mm.
As shown in FIG. 8, when the gap length is large, a certain ion current can be obtained with a bias voltage of −500 V even with a uniform magnetic field. However, as shown in FIG. 7, the gap length is 1.8 mm. Assuming that the interval is small, when the uniform magnetic field is used, the bias voltage is −300 V, the ion current is extremely small, and sputtering does not occur.
On the other hand, when the mirror magnetic field according to the present invention is used, as is apparent from FIG. 6, an ion current is obtained even when the bias voltage Vb is −300 V, and it can be seen that sputtering is possible. Thus, by increasing the bias voltage, the energy of sputtering can be increased, and the sputtering efficiency can be increased.

FIG. 9 is a diagram in which the effect in the case of using a mirror magnetic field is evaluated by absorption spectroscopy for axial uniformity. In this case, sputtering is performed on a Pyrex glass tube, Ar is used as an introduction gas, the inside of the vacuum vessel is 70 mTorr, the microwave input power is 30 W, the magnetic field strength is 438 gauss at the center of the coil, the target diameter is 2 mm, the gap The length (interval between the target 5 and the microtubule 4) was 1.8 mm, the pulse frequency was 2 kHz, and the pulse width was 35 μm.
In this case, the light transmitted through the Pyrex glass tube is detected by a spectrometer, and the film thickness is relatively evaluated by comparing the light intensity when the film is not formed and the light intensity when the film is formed. did.
The magnetic field at this time is a value at the center point, and is a position 25 mm from the microwave entrance (0 mm). Furthermore, the microwave is input in the coaxial mode from the microwave entrance side.

A curve A in FIG. 9 is a case where the mirror ratio (maximum magnetic flux density / minimum magnetic flux density) is 1.51, and a curve B is a magnetic field by a simple solenoid that is not a mirror magnetic field. As is apparent from the curve B, it can be seen that when the magnetic field does not depend on the mirror magnetic field, a large amount of sputtered material is deposited on the microwave introduction portion, resulting in poor uniformity. This is considered to be caused by the fact that the plasma does not resonate and is shifted to the microwave discharge by the power of the microwave.
As conditions for easily shifting to microwave discharge, there may be reasons such as microwave incidence from a weak magnetic field, microwave power, and high operating pressure. In addition, when the mirror ratio is changed, setting the mirror ratio high will increase the magnetic field intensity near the microwave introduction part, suppress the discharge, and efficiently power the plasma by microwave incidence from the strong magnetic field side. This is thought to be due to the phenomenon of resonance and improved plasma uniformity. From the above results, it was found that the use of a mirror magnetic field not only improves the plasma density but also improves the axial uniformity.

  In the embodiment described above, the second ultra-thin shaft body 5 side on the central axis is configured to have a sputter target or a sputter target disposed on the outer periphery, and the first ultra-thin shaft body 4 of the outer micro-tube is covered. As the sputtering, the case where the coating material is sputtered on the inner periphery has been mainly described. However, this arrangement relationship is reversed, and the outer first very long shaft 4 is disposed on the sputter target or on the inner periphery. In addition, an embodiment in which the sputtered material is coated on the outer peripheral surface of the sputtered object may be a sputtered object that is a fine tube or a wire-like second ultrathin shaft 5 on the central axis.

As described above, according to the present invention, by using the mirror magnetic field, not only the plasma density but also the axial uniformity can be improved, and the electron confinement by the harmonic ECR described above can be achieved. Combined with the improvement of the plasma density by the mirror magnetic field, the sputter coating can be performed uniformly on the inner surface of the long tube.
Further, in the present invention, the first and second very long shafts 4 and 5 are arranged in the direction of gravity, so that they are always tensioned with a required tension by their own weight or by connecting the tension applying means 50. Can do. Therefore, the mutual positional relationship between the first and second ultrathin shafts 4 and 5 can be stably maintained, whereby sputtering under more stable conditions can be performed.

That is, when these first and second ultra-thin shafts 4 and 5 are arranged in the horizontal direction as usual, the center second ultra-thin shaft is particularly affected by thermal expansion due to temperature rise during operation. 5 is easier to bend when it is thinner than the first diameter, and when it is a sputter target, it becomes more unstable due to thinning by sputtering.
However, as described above, in the configuration of the present invention, the first and second very long shaft bodies 4 and 5 are arranged in the direction of gravity, so that their own weight or tension applying means 50 can be combined to always provide the required. Since it can be tensioned with tension, the positional relationship between the first and second extra long shafts 4 and 5 can be stably maintained.
Therefore, stable and uniform sputtering film formation can be performed.

Examples of the object to be sputtered in the above-described coating method and coating apparatus for an ultra-long shaft according to the present invention include medical devices that come into contact with living bodies or biological components represented by, for example, catheters, guide wires, and stents. It is a base material of a medical material that forms an instrument, and can be a metal material, a ceramic material, a polymer material such as rubber or resin, or a composite thereof.
The shape depends on materials such as wires and tubes used for medical instruments, and those formed in the shape of medical instruments and in the middle of formation.

The object to be sputtered is not particularly limited. For example, a metal such as iron, nickel, chromium, copper, titanium, platinum, tungsten, or tantalum can be used. Further, these alloys are stainless steel such as SUS316L, shape memory alloy such as Ti—Ni alloy or Cu—Al—Mn alloy, Cu—Zn alloy, Ni—Al alloy, titanium alloy, tantalum alloy, platinum alloy or An alloy such as a tungsten alloy can also be used. Further, it may be a bioactive ceramic such as oxide such as aluminum, silicon or zircon, nitride or carbide, or a bioactive ceramic such as apatite or biological glass. Further, it may be a polymer resin such as polymethyl methacrylate (PMMA), high density polyethylene or polyacetal, a silicon polymer such as polydimethylsiloxane, or a fluorine polymer such as polytetrafluoroethylene.
When the object to be sputtered is a dielectric, the distance between the electrodes can be substantially adjusted by interposing a dielectric material between the object to be sputtered and the outer electrode 2 or the center electrode facing the object. It is something that can be done.

  In the present invention, various sputter materials can be applied. As the sputter target, targets including gold, silver, titanium, copper, platinum, chromium, nickel or other metals, and non-conductive materials such as ceramic materials can also be used. However, when a non-conductive material is used, it is necessary to use a non-conductive material on the conductor to prevent the introduction of microwaves and to use an RF bias as a bias. Furthermore, a mixed target such as titanium / aluminum may be used. Moreover, a carbon-type material etc. can be used.

  In addition, the coating method and coating apparatus by this invention are not limited to the example mentioned above, It cannot be overemphasized that a various change can be performed according to a use purpose.

A and B are the longitudinal cross-sectional view of the principal part of the coating apparatus with which it uses for demonstrating the fundamental operation | movement of this invention, and its sectional drawing on the BB line. A and B are diagrams showing electron trajectories in the case of 2nd Harmonic ECR (ωce / ω = 0.5) and ECR (ωce / ω = 1). It is a figure which shows a mirror magnetic field distribution. It is a schematic block diagram of one embodiment of the coating apparatus by this invention. It is a flowchart of this invention method. It is a figure which shows the change of the target pulse bias voltage and ion current density in the case of using a mirror magnetic field. It is a figure which shows the change of the target pulse bias voltage and ion current density in the case of a uniform magnetic field. It is a figure which shows the change of the target pulse bias voltage and ion current density in the case of a uniform magnetic field. It is a figure which shows the influence which a magnetic field gradient gives to an axial direction uniformity.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Vacuum container, 2 ... Outer electrode, 3 ... Center electrode, 4 ... Ultra-thin tube, 5 ... Sputter target, 6 ... Power supply part <pulse bias supply source>, 7 ... Ion, 8 ... Atom, 9 ... Vacuum exhaust device, 10 ... Plasma source gas supply source, 11 ... Mass flow controller, 12 ... Mirror magnetic field generator, 13 ... Excitation current source, 14 ... Microwave generator, 15 ... Power monitor, 16 ... Stabilizing tuner, 17 ... Coaxial cable, C (C1, C2, C3, ... Cn) ... Coil, 50 ... Tension applying means

Claims (7)

In the vacuum region, the first and second elongated shaft bodies by the ultrathin tubes are arranged on the same axis in the gravity direction while maintaining a required gap between the two elongated shaft bodies. ,
In this state, one of the first and second very long shafts is used as a sputter target, the other is used as a sputter target, and a voltage with the sputter target side as a negative side is applied.
A plasma source gas is introduced into the gap, and a harmonic ECR (Electron Cyclotron Resonance) plasma is generated by introducing a microwave and applying a mirror magnetic field, thereby generating an inner peripheral surface of the first very long shaft body or the second And coating the sputter target material on the outer peripheral surface of the extra-long elongate shaft body.   2. The method for coating an ultra-long elongated shaft body according to claim 1, wherein the mirror magnetic field is moved in the axial direction to move a main plasma generation unit in the axial direction.   2. The coating method for an ultra-long elongated shaft body according to claim 1, wherein a negative voltage pulse bias is repeatedly applied to the sputter target side. A vacuum vessel;
A mirror magnetic field generator disposed on the outer periphery of the vacuum vessel;
A plasma source gas supply source;
A microwave generator;
In the vacuum vessel,
A very long shaft body in which a first ultra long shaft body and a second ultra long shaft body by a micro tube are arranged coaxially along the direction of gravity and with a required gap between the two long shaft bodies. A placement section;
A power supply unit for applying a required voltage between the first and second elongated shafts;
A voltage is applied with one of the first and second ultrathin shafts as a sputtering target, the other as a sputter target and the sputtering target side as a negative side, and the plasma source gas source in the gap. The plasma source gas is introduced from the above, and a harmonic ECR (Electron Cyclotron Resonance) plasma is generated by the introduction of the microwave and the application of the mirror magnetic field by the microwave generator and the mirror magnetic field generator, thereby generating the first ultra-long slit. An apparatus for coating an ultra-long elongate shaft body, wherein the sputter target material is coated on an inner circumferential surface of the shaft body or an outer circumferential surface of the second ultra-long elongate shaft body.   5. A tension applying means for applying a required tension in the direction of gravity along the axial direction is disposed on the second elongated shaft body at the arrangement portion of the elongated shaft body. An apparatus for coating an ultra-long elongate shaft described in 1.   The magnetic field generator is configured by arranging a plurality of electromagnetic coils on the outer periphery of the vacuum vessel along the axial direction of the first and second very long shafts. 5. The coating apparatus for an ultra-long elongate shaft body according to claim 4, wherein the main plasma generation position is moved along the axial center direction of the ultra-thin tube by switching the energization amount. 5. The power supply unit that applies a required voltage between the microtubule and the sputter target is a power supply unit that applies a negative voltage pulse bias to the sputter target side. A coating device for ultra-thin shafts.

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