JP4571425B2 - Plasma generator and thin film forming apparatus - Google Patents

Description

  The present invention relates to a plasma generating apparatus configured to guide electrons to the outside from plasma generated inside, and a thin film forming apparatus using such a plasma generating apparatus.

  Plasma generators are used in thin film forming apparatuses such as ion plating apparatuses and plasma CVD apparatuses.

  FIG. 1 shows an outline of an ion plating apparatus provided with a plasma generator, and FIG. 2 shows details of the plasma generator. In the figure, reference numeral 1 denotes a vacuum vessel of an ion plating apparatus, and a crucible 3 containing an evaporation material 2 and an electron gun 4 for irradiating the evaporation material with an electron beam are provided at the bottom of the vacuum vessel. Yes. On the other hand, a substrate 6 to which a negative voltage is applied from the substrate power supply 5 is attached to the upper part of the vacuum vessel. In the figure, reference numeral 7 denotes a plasma generator supported at the bottom of the vacuum vessel by a support base 8, the details of which will be described later. An electron beam from the plasma generator is irradiated between the substrate 6 and the crucible 3. It is made like this. In the figure, 9 is a vacuum pump, 10 is a valve, 11 is a reactive gas cylinder, 12 is a valve, 13 is a discharge gas cylinder, and 14 is a valve.

  FIG. 2 shows an outline of the plasma generator, and 15 is a case for forming a discharge chamber. A cathode 16 is disposed in the case, and the cathode is connected to a heating power source 17 and also to a discharge power source 18. The case is provided with a discharge gas supply pipe 19, and an inert gas such as Ar gas is introduced into the case from the discharge gas cylinder 13 through the discharge gas supply pipe 19. At one end of the case, a ring-shaped first anode 21 </ b> A is provided on the case 15 via an insulator 20. The first anode is formed of, for example, stainless steel and is formed in an annular shape. In order to prevent damage due to heat of other parts of the discharge chamber including the first anode 21A, the first anode is formed in the first anode. Cooling water is flowing through the provided water channel WP. In addition, a ring-shaped second anode 21B made of a high melting point material (for example, molybdenum) is connected to the opposite side of the first anode. The connection between the first cathode 21A and the second anode 21B is made by connecting a part of each other so that the thermal resistance between them is increased. Inside each anode, a shield electrode 22 is arranged so that electrons from the cathode 16 are not directly irradiated to each anode. The tip of the shield electrode 22 forms an orifice through which the electron beam passes. The case 15 is connected to the discharge power source 18 via a resistor R1, and the anodes 21A and 21B are connected to the discharge power source 18 via a resistor R2. Further, the vacuum vessel 1 is connected to a discharge power source 18 via a resistor R3. The resistance values of these resistors are usually R1 >> R3> R2, and most of the current flowing through the discharge power supply 18 is a discharge current between the anodes 21A and 21B and the cathode 16. In the figure, reference numeral 23 denotes a coil constituting an electromagnet for shaping the discharge current in the case, and is provided outside the case.

  In the ion plating apparatus having such a configuration, first, the valve 10 is opened, and the vacuum vessel 1 and the case 15 are evacuated by the vacuum pump 9 until a predetermined pressure is reached. Then, the valve 14 is opened, a predetermined amount of discharge gas (for example, Ar gas) is introduced into the case 15 from the discharge gas cylinder 13 via the discharge gas supply pipe 19, the pressure in the case 15 is increased, and the cathode 16 is heated to the power source. 17 is heated to a temperature at which thermionic electrons can be emitted.

  Next, a predetermined current is passed through the coil 23 to generate a magnetic field necessary for ignition of the plasma and maintenance of a stable plasma in the axial direction of the electron beam. In this state, when a predetermined voltage is applied from the discharge power source 18 to the cathode 16 and the first and second anodes 21 </ b> A and 21 </ b> B, initial discharge occurs between the cathode 16 and the case 15. Plasma is generated in the case 15 by this initial discharge as a trigger. Electrons in the discharge plasma are focused in the axial direction of the electron beam due to the magnetic field formed by the coil 23, and are vacuumed by an accelerating electric field generated near the tip of the shield electrode 22 near the second anode 21B. It is drawn into the container 1.

  On the other hand, in the inside of the vacuum vessel 1, the electron beam from the electron gun 4 is irradiated toward the material to be evaporated 2, and the material to be evaporated is heated and evaporated. Further, a reaction gas (for example, oxygen gas) is introduced into the vacuum container 1 from the reaction gas cylinder 11 by opening the valve 12. The electron beam extracted from the plasma generator 7 collides with the reaction gas and evaporated particles introduced into the vacuum vessel 1, and excites and ionizes them to form plasma P in the vacuum vessel 1. The ionized evaporated particles and the reactive gas in the plasma are attracted to the substrate 6 to be attached or ion bombarded, and evaporated particles are formed on the substrate.

  The electrons drawn from the plasma generator 7 into the vacuum vessel 1 and the electrons in the plasma P flow into the vacuum vessel 1 and the first and second anodes 21A and 21B, and stable discharge is maintained. The strength of the plasma P can be controlled by the discharge gas flow rate and the heating temperature of the cathode 16. In addition, the relationship between the resistance values of the resistors R2 and R3 is R3> R2, but the relationship between the resistance values is arbitrarily changed to R3 = R2, R3> R2, R3 <R2, R3 << R2. Thus, the amount of current flowing through the anodes 21A and 21B and the vacuum vessel 1 can be freely selected.

JP 2001-143894 A

  For example, when an optical thin film is formed by an ion plating apparatus having such a structure, it is generally performed in an oxide atmosphere. In that case, the relationship of the resistance values is such that R3> R2, so that most of the discharge current flows to the second anode 21B. As described above, the heat resistance between the first anode 21A and the second anode 21B is increased, and the second anode 21B is heated to 800 ° C. by the heat generated when the discharge current flows into the second anode 21B. It is configured to be heated to about 1200 ° C. As described above, when the second anode 21B is heated to a high temperature, the second anode 21B functions to maintain the conductivity of the surface thereof, and thus can operate stably in an oxide atmosphere.

  However, as described above, the first anode 21A and the second anode 21B are connected to each other so that the thermal resistance between them is increased. That is, a female screw is formed on the side surface S1 parallel to the central axis of the first anode 21A, and a male screw is formed on the outer side surface S2 parallel to the central axis of the second anode 21B. The first anode 21A and the second anode 21B are connected by screwing the male thread portion of the two anode 21B. In FIG. 2, it appears that the upper surface of the first anode 21A and the lower surface of the second anode 21B are connected, but they are not connected, and the male screw portion of the second anode 21B is completely screwed into the female screw portion of the first anode 21A. At that time, it is far enough to make a very small gap.

  However, when the second anode 21B is heated to a high temperature, the contact portion of the first anode 21A with the second anode 21B becomes a high temperature and thermally expands, and when the second anode 21B cools, the first anode 21A has a second temperature. The contact portion with the two anodes 21B contracts. Accordingly, the contact portion between the first anode 21A and the second anode 21B repeats thermal expansion and contraction, and as a result, the internal thread portion of the first anode 21A is thermally deformed. It becomes difficult to remove the anode 21B from the first anode 21A.

  Therefore, the state of the internal thread portion of the first anode 21A is constantly inspected, and tap processing is performed as necessary. However, if the tap processing is repeated, the internal thread portion of the first anode 21A is consumed, and the function as a screw is achieved. It deteriorates and further shortens the service life as a component.

  The present invention has been made to solve such problems, and an object of the present invention is to provide a novel plasma generating apparatus and thin film forming apparatus.

The plasma generator of the present invention comprises a discharge chamber, a cathode disposed in the discharge chamber, a cylindrical first anode disposed at an end of the discharge chamber, and a two-stage cylindrical shape. A second anode disposed outside the first anode so as to be partially connected to the first anode by inserting the small-diameter cylindrical portion into the hole of the first anode; A cylindrical shield body partially inserted into the hole of the small-diameter cylindrical portion of the second anode, and attached to the discharge chamber so that at least the two anodes are hidden when viewed from the cathode, and the cathode And a discharge power source for applying a discharge voltage between any of the anodes and means for supplying a discharge gas into the discharge chamber, and electrons in the plasma formed in the discharge chamber Through a part of the shield body In the plasma generating apparatus configured to irradiate the vacuum vessel of the discharge outside, the peripheral surface forming the first anode of the hole, parallel to the central axis, that it has a plurality of grooves at intervals Features.

The thin film forming apparatus of the present invention includes a discharge chamber, a cathode disposed in the discharge chamber, a cylindrical first anode disposed at an end of the discharge chamber, and a two-stage cylindrical shape. And a second cylindrical portion disposed outside the first anode so as to be partially connected to the first anode by inserting the small diameter cylindrical portion into the hole of the first anode. An anode, and a cylindrical shield body, part of which is inserted into the hole of the small-diameter cylindrical portion of the second anode, and attached to the discharge chamber so that at least the two anodes are hidden when viewed from the cathode; A discharge power source for applying a discharge voltage between the cathode and any one of the anodes, and a means for supplying a discharge gas into the discharge chamber, the plasma being formed in the discharge chamber Through a part of the shield body A plasma generator configured to irradiate the vacuum chamber outside the discharge chamber, and at least the vaporized material in the vacuum chamber is irradiated with electrons from the plasma generator to generate plasma to generate a plasma on the substrate; In the thin film forming apparatus configured to form a film, a plurality of grooves are formed on the peripheral surface forming the hole portion of the first anode at intervals in parallel to the central axis.

  According to the present invention, maintenance of the plasma generator is performed smoothly (easy). As a result, the maintainability of the plasma generator is improved, and the first anode and the second anode, which are components of the plasma generator, are provided. Will prolong the service life.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 3 shows an example of the plasma generator of the present invention. In the figure, the same reference numerals as those used in FIG. 2 denote the same components.

  Differences in configuration between the apparatus shown in FIG. 3 and the apparatus shown in FIG. 2 will be described below.

  In the apparatus shown in FIG. 3, the connection portion between the first anode 21A ′ and the second anode 21B ′ is different from that in FIG.

  That is, in the apparatus shown in FIG. 3, the second anode 21B ′ is not screwed into the first anode 21A ′, but is inserted.

  Therefore, as shown in the perspective view of FIG. 4, the outer surface of the small cylindrical portion Q inserted into the first anode 21A ′ of the two-stage cylindrical second anode 21B ′ is not cut off by the screw. The curved finish remains.

  On the other hand, the hole P into which the small cylindrical portion Q of the second anode 21B ′ of the cylindrical first anode 21A ′ is inserted is a perspective view (FIG. 5), an upper sectional view (FIG. 6 (a)), and an upper sectional view. As shown in the AA cross-sectional view (FIG. 6B), it is composed of a shallow hole PA and a deep hole PB in two stages, and the peripheral surface of the deep hole PB is Semi-cylindrical grooves 23A, 23B, 23C, and 23D are formed at equal intervals in the axial direction. In addition, as shown in FIG. 6, both side edge portions of the semi-cylindrical grooves 23A, 23B, 23C, and 23D are finished into curved surfaces so as not to be angular (heat concentrates on the angular portions). ing.

  The hole portion PB of the first anode 21A ′ and the small cylindrical portion Q of the second anode 21B ′ are arranged so that the small cylindrical portion Q of the second anode 21B ′ is inserted into the hole portion PB of the first anode 21A ′. When the anode 21A ′ is not thermally expanded, it is natural that the diameter of the hole portion PB must be larger than the diameter of the small cylindrical portion Q. When the first anode 21A ′ is thermally expanded, The diameter of the hole PB and the small cylindrical part Q are formed so that the difference between the diameter of the part PB and the diameter of the small cylindrical part Q is 0.15 mm or more and 0.5 mm or less.

  Further, as described above, four semi-cylindrical grooves (23A, 23B, 23C, 23D) are formed at equal intervals in the axial direction on the peripheral surface of the deep hole PB of the first anode 21A ′. However, the number of the grooves is not limited to four, and more grooves may be provided. However, the number and size of the grooves are set so that the area in which the first anode 21A ′ is thermally expanded and contacts the first anode 21B ′ is, for example, 55% to 90% of the whole.

  The thermal expansion of the first anode 21A ′ is absorbed by the grooves (23A, 23B, 23C, and 23D), but the deformation based on the thermal expansion of the first anode 21A ′ that cannot be completely absorbed is the second anode 21B ′. Will lift. Thus, in order to absorb thermal expansion that cannot be absorbed by the grooves (23A, 23B, 23C, 23D), the first anode 21A 'is provided with a shallow hole PA. The depth of the hole PA is set to a size larger than the maximum saturation value of thermal expansion that cannot be absorbed (for example, 0.5 mm).

  When the plasma generator having such a configuration is applied to, for example, an ion plating apparatus as shown in FIG. 1, it operates as follows.

  First, the valve 10 is opened, and the vacuum vessel 1 and the case 15 are evacuated by the vacuum pump 9 until a predetermined pressure is reached. Then, the valve 14 is opened, a predetermined amount of discharge gas (for example, Ar gas) is introduced into the case 15 from the discharge gas cylinder 13 via the discharge gas supply pipe 19, the pressure in the case 15 is increased, and the cathode 16 is heated to the power source. 17 is heated to a temperature at which thermionic electrons can be emitted.

  Next, a predetermined current is passed through the coil 23 to generate a magnetic field necessary for ignition of the plasma and maintenance of a stable plasma in the axial direction of the electron beam. In this state, when a predetermined voltage is applied from the discharge power source 18 to the cathode 16 and the first and second anodes 21A ′ and 21B ′, initial discharge occurs between the cathode 16 and the case 15. Plasma is generated in the case 15 by this initial discharge as a trigger. Electrons in the discharge plasma are focused in the axial direction of the electron beam due to the magnetic field formed by the coil 23, and are generated by an accelerating electric field generated near the tip of the shield electrode 22 near the second anode 21B '. It is pulled out into the vacuum vessel 1. The thermoelectrons from the cathode 16 are not directly applied to the first anode 21A ′ by the shield electrode 22.

  On the other hand, in the inside of the vacuum vessel 1, the electron beam from the electron gun 4 is irradiated toward the material to be evaporated 2, and the material to be evaporated is heated and evaporated. Further, a reaction gas (for example, oxygen gas) is introduced into the vacuum container 1 from the reaction gas cylinder 11 by opening the valve 12. The electron beam extracted from the plasma generator 7 collides with the reaction gas and evaporated particles introduced into the vacuum vessel 1, and excites and ionizes them to form plasma P in the vacuum vessel 1. The ionized evaporated particles and the reactive gas in the plasma are attracted to the substrate 6 to be attached or ion bombarded, and evaporated particles are formed on the substrate.

  Now, for example, when an optical thin film is formed by the ion plating apparatus having such a structure, as described above, the relation of the resistance value is R3> R2, and most of the discharge current is the second anode 21B. It seems to flow to ´. At this time, the second anode 21B ′ is heated from about 800 ° C. to about 1200 ° C. by heat generated when the discharge current flows into the second anode 21B ′.

  When the second anode 21B ′ is heated to such a high temperature, the contact portion of the first anode 21A ′ with the second anode 21B ′ also becomes high temperature and thermally expands. At this time, since the water channel WP through which the cooling water flows is provided in the first anode 21A ′, the thermal expansion of the contact portion occurs in the central axis direction.

Most of the thermal expansion in the direction of the central axis is caused by the semi-cylindrical grooves 23A, 23B, 23C, and 23D formed at equal intervals in the axial direction on the peripheral surface of the deep hole PB of the first anode 21A ′. Absorbed. Further, thermal expansion that cannot be absorbed by the groove is absorbed by the shallow hole PA of the first anode 21A ′.
As a result, the second anode 21B ′ can be easily detached from the first anode 21A ′ during maintenance, and frequent inspection of the second anode 21B ′ and the first anode 21A ′ is not required, improving the maintainability.

  Further, since there is no need for a tap process or the like on the first anode 21A ′ or the like, the function of the first anode 21A ′ and the second anode 21B ′ as a screw is prevented from being deteriorated, and the life as a component is extended.

  In addition, this invention is not limited to the example of FIGS. For example, the groove formed in the peripheral surface of the hole PB of the first anode 21A ′ is not limited to a semi-cylindrical shape, and may be another curved column shape or a prism shape. Further, the intervals between the grooves are not necessarily equal.

1 schematically shows an ion plating apparatus provided with a plasma generator. The outline of the conventional plasma generator is shown. An example of the plasma generator of the present invention is shown. Fig. 4 shows an outline of a second anode used in the plasma generator shown in Fig. 3. 4 schematically shows a first anode used in the plasma generator shown in FIG. 3. 4 schematically shows a first anode used in the plasma generator shown in FIG. 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Vacuum container 2 ... Material to be evaporated 3 ... Crucible 4 ... Electron gun 5 ... Substrate power supply 6 ... Substrate 7 ... Plasma generator 8 ... Support stand
DESCRIPTION OF SYMBOLS 9 ... Vacuum pump 10 ... Valve 11 ... Reaction gas cylinder 12 ... Valve 13 ... Discharge gas cylinder 14 ... Valve 15 ... Case 16 ... Cathode 17 ... Heating power supply 18 ... Discharge power supply 19 ... Discharge gas supply pipe 20 ... Insulator 21A, 21A '... No. 1 anode 21B, 21B '... 2nd anode 22 ... shield electrode WP ... water channel Q ... small cylindrical part 23A, 23B, 23C, 23D ... groove P ... hole PA ... shallow hole part PB ... deep hole part

Claims (12)

A discharge chamber, and a cathode disposed the discharge chamber, a first anode of cylindrical shape disposed at the end of the discharge chamber, forms a cylindrical shape of the twofold, the smaller cylindrical portion A second anode disposed outside the first anode and a part of the second anode are inserted into the hole of the first anode so as to be partially connected to the first anode. A cylindrical shield body, which is inserted into the hole of the small-diameter cylindrical portion and attached to the discharge chamber so that at least the two anodes are hidden when viewed from the cathode, and the cathode and any one of the anodes A discharge power source for applying a discharge voltage therebetween, and means for supplying a discharge gas into the discharge chamber. Electrons in plasma formed in the discharge chamber are passed through a part of the shield body. In a vacuum vessel outside the discharge chamber In the plasma generating apparatus configured to Isa, the circumferential surface forming the first anode of the hole, parallel to the central axis, the plasma generating apparatus characterized by forming a plurality of grooves at intervals. Wherein the first anode of the hole portion is formed in the twofold small holes having deeper diameter larger hole of shallow diameter, smaller cylindrical portion of the second anode is inserted into the small hole portion of deeply diameter The plasma generating apparatus according to claim 1, wherein a plurality of grooves are formed on the peripheral surface of the deep and small-diameter hole portion in parallel with the central axis at intervals. The plasma generator according to claim 1, wherein the groove has a semi-cylindrical shape. The plasma generator according to claim 1, wherein the number of the grooves is four or more. The plasma generator according to claim 1, wherein a water channel through which cooling water flows is provided inside the first anode. The plasma generator according to claim 1, wherein the intervals are equal intervals. A discharge chamber, and a cathode disposed the discharge chamber, a first anode of cylindrical shape disposed at the end of the discharge chamber, forms a cylindrical shape of the twofold, the smaller cylindrical portion A second anode disposed outside the first anode and a part of the second anode are inserted into the hole of the first anode so as to be partially connected to the first anode. A cylindrical shield body, which is inserted into the hole of the small-diameter cylindrical portion and attached to the discharge chamber so that at least the two anodes are hidden when viewed from the cathode, and the cathode and any one of the anodes A discharge power source for applying a discharge voltage therebetween, and means for supplying a discharge gas into the discharge chamber. Electrons in plasma formed in the discharge chamber are passed through a part of the shield body. In a vacuum vessel outside the discharge chamber A plasma generating device configured to irradiate the substrate, and at least a vapor deposition material in the vacuum vessel is irradiated with electrons from the plasma generating device to generate plasma to form a substrate. in the thin film forming apparatus, the peripheral surface forming the first anode of the hole, parallel to the central axis, the thin film forming apparatus characterized by forming a plurality of grooves at intervals. Wherein the first anode of the hole portion is formed in the twofold small holes having deeper diameter larger hole of shallow diameter, smaller cylindrical portion of the second anode is inserted into the small hole portion of deeply diameter The thin film forming apparatus according to claim 7, wherein a plurality of grooves are formed at intervals in parallel to the central axis on a peripheral surface forming the deep and small hole portion . The thin film forming apparatus according to claim 7 or 8, wherein the groove has a cylindrical shape. The thin film forming apparatus according to claim 7 or 8, wherein the number of the grooves is four or more. The thin film forming apparatus according to claim 7, wherein a water channel through which cooling water flows is provided inside the first anode. The thin film forming apparatus according to claim 7 or 8, wherein the intervals are equal intervals.

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