HK1088046B - Thin film forming device - Google Patents

Description

Thin film forming apparatus

Technical Field

The present invention relates to a thin film forming apparatus for manufacturing a thin film used in an optical thin film, an optical device, an optoelectronic device, a semiconductor device, and the like, and more particularly, to a thin film forming apparatus for improving the density of an active species chemically reacting with a thin film by improving a plasma generating means and a vacuum chamber.

Background

Conventionally, plasma processing such as thin film formation, surface modification of a thin film after formation, and etching has been performed on a substrate using a reactive gas formed into plasma in a vacuum chamber. For example, the following techniques are known: a thin film made of an incomplete reactant of a metal is formed on a substrate by sputtering, and the thin film made of the incomplete reactant is brought into contact with a reactive gas which has been turned into a plasma, thereby forming a thin film made of a metal compound (for example, japanese patent laid-open No. 2001-234338).

In this technique, a plasma generating means is used to convert a reactive gas into plasma in a vacuum chamber provided in a thin film forming apparatus. The gas that has been converted into plasma by the plasma generation means contains ions, electrons, atoms, molecules, and active species (radicals, excited-state radicals, and the like). In many cases, electrons and ions contained in the plasma-formed gas may damage the thin film, while the radicals of the electrically neutral reactive gas are advantageous for forming the thin film. Thus, conventionally, a grid (grid) is used to prevent electrons and ions from being directed to a thin film on a substrate and to selectively contact radicals with the thin film. Thus, by using the grid, the relative density of the radicals in the plasma gas, which is favorable for forming the thin film, can be increased, and the efficiency of the plasma treatment can be increased.

However, if a grid is used to increase the relative density of radicals, there are the following problems: the structure of the thin film forming apparatus becomes complicated, and the distribution area of radicals in the vacuum vessel is limited by the size, shape, and arrangement of the grid. Such a problem prevents plasma treatment from being performed over a wide range, and becomes a factor of non-high efficiency of plasma treatment, and as a result, improvement of production efficiency of a thin film is prevented. Further, if the gate is enlarged to enlarge the distribution region of the radicals, a problem of cost increase also arises.

However, as a plasma generating means for generating plasma, a parallel plate type, an ECR type, an induction coupling type, or the like is known. As the induction coupling type device, a cylindrical type and a flat type are known.

Fig. 10 is a diagram illustrating a conventional plasma generator 161 of a flat plate type. FIG. 10A is a partial sectional view showing a thin film forming apparatus. As shown in fig. 10A, a conventional flat-plate plasma generating unit is configured such that a dielectric plate 163 made of a dielectric material such as quartz forms a part of a vacuum chamber 111, and an antenna (antenna)165 is disposed along an outer wall of the dielectric plate 163 on the atmosphere side.

Fig. 10B shows the shape of the antenna 165. The antenna 165 is swirled in the same plane. A conventional flat-plate plasma generator 161 generates plasma in a vacuum chamber 111 by applying power having a frequency of 100kHz to 50MHz to an antenna 165 via a matching box 167 having a matching circuit by using a high-frequency power supply 169.

As shown in a matching box 167 of fig. 10, the application of high-frequency power to the antenna 165 is performed by a matching circuit for impedance matching. As shown in fig. 10, the matching circuit connected between the antenna 165 and the high-frequency power supply 169 includes variable capacitors 167a and 167b and a matching coil 167 c.

In the known plasma generating unit, when plasma processing is performed over a wide range in a vacuum chamber, although the antenna 165 is enlarged, there is a problem that: power loss between the antenna 165 and the matching coil 167c increases, and it is difficult to obtain impedance matching. In addition, when the plasma treatment is performed over a wide range, there is also a problem that the density of the plasma is not uniform depending on the place.

Disclosure of Invention

In view of the above problems, an object of the present invention is to provide a thin film forming apparatus capable of efficiently performing plasma processing over a wide range.

The thin film forming apparatus of the present invention includes: a vacuum container whose inside is maintained to be vacuum; a gas introduction unit for introducing a reactive gas into the vacuum vessel; a plasma generation unit that generates plasma of the reactive gas in the vacuum chamber, the plasma generation unit including: a dielectric wall disposed on an outer wall of the vacuum chamber; the first antenna and the second antenna are vortex-shaped; and a lead wire for connecting the first antenna and the second antenna to a high-frequency power supply, wherein the thin-film forming apparatus includes an antenna fixing unit for fixing the first antenna and the second antenna at positions corresponding to the wall of the dielectric body outside the vacuum chamber, the first antenna and the second antenna are connected in parallel to the high-frequency power supply, and a position adjusting unit for adjusting a distance between the first antenna and the second antenna is provided at a portion connected to the lead wire at a position where the first antenna and the second antenna are connected.

In this way, since the thin film forming apparatus of the present invention includes the first antenna and the second antenna, the distribution of plasma can be easily adjusted by independently adjusting the thickness, shape, size, diameter, and the like of the first antenna and the second antenna. In addition, since the thin film forming apparatus of the present invention includes the position adjusting means for adjusting the interval between the first antenna and the second antenna at the portion of the wire from the high-frequency power supply to the first antenna and the second antenna, which connects the first antenna and the second antenna, the distribution of plasma can be easily adjusted by adjusting the interval between the first antenna and the second antenna. In addition, by connecting the first antenna and the second antenna in parallel, even in the case where the matching circuit is connected to the first antenna and the second antenna, impedance matching can be easily obtained by the matching circuit, and power loss in the matching circuit can be reduced, so that power can be effectively utilized for generation of plasma.

In this case, the vacuum chamber may include a substrate transfer unit for transferring a substrate, the substrate transfer unit may transfer the substrate so that the substrate faces the first antenna and the second antenna in a spiral shape, and the first antenna and the second antenna may be fixed to each other in a state where the first antenna and the second antenna are adjacent to each other in a direction intersecting a direction in which the substrate is transferred by the substrate transfer unit.

In this way, by fixing the first antenna and the second antenna in a state in which they are adjacent to each other in a direction intersecting the substrate conveying direction, the plasma density distribution in the direction perpendicular to the substrate conveying direction can be easily adjusted. Therefore, by performing the plasma processing in a wide range in a direction perpendicular to the substrate conveying direction, the plasma processing can be performed on a large number of thin films at once.

Further, the first antenna and the second antenna are preferably configured by: a circular tubular body portion formed from a first material; the coating layer on the surface of the main body is coated with a second material having a lower resistance than the first material.

By adopting such a configuration, the main bodies of the first and second antennas are formed of a first material which is inexpensive and easy to process, and the coat layer in which the current is concentrated is formed of a second material having a small resistance, so that the high-frequency impedance of the antenna can be reduced, and a thin film can be efficiently formed.

Other advantages of the present invention will become apparent from the following description.

Drawings

Fig. 1 is a schematic plan view partially in cross section illustrating a thin film forming apparatus according to the present invention.

FIG. 2 is a schematic side view partially in cross section illustrating a thin film forming apparatus according to the present invention.

Fig. 3 is a schematic view illustrating a plasma generating unit.

Fig. 4 is a cross-sectional view of the antenna.

FIG. 5 is a diagram showing an example of experimental results for determining the ratio of oxygen atoms to oxygen ions in a plasma.

Fig. 6 is a diagram showing an example of the experimental results of measuring the emission intensities of oxygen radicals and oxygen ions in an excited state existing in plasma.

Fig. 7 is a diagram showing an example of the experimental result of measuring the flow density of oxygen radicals in plasma.

Fig. 8 is a diagram showing an example of the results of an experiment for measuring the film transmittance in the case of forming a multilayer film of silicon oxide and niobium oxide using a conventional plasma generation unit.

FIG. 9 is a view showing an example of the result of an experiment for measuring the transmittance of a thin film in the case of forming a multilayer thin film of niobium oxide and silicon oxide using the plasma cell of the present invention.

Fig. 10 is a diagram illustrating a conventional plasma generating unit of a flat plate type.

Detailed Description

An embodiment of the present invention will be described below with reference to the drawings. The present invention is not limited to the components and arrangement described below, and various modifications are possible within the spirit of the present invention.

Fig. 1 and 2 are schematic views illustrating a sputtering apparatus 1. To facilitate understanding, fig. 1 is a schematic top view in partial section, and fig. 2 is a schematic side view in partial section along the line a-B-C of fig. 1. The sputtering apparatus 1 is an example of the thin film forming apparatus of the present invention.

In this example, the sputtering apparatus 1 that performs magnetron sputtering (マグネトロンスパッタ) is used as an example of sputtering, but the present invention is not limited to this, and other known sputtering apparatuses such as bipolar sputtering that does not use magnetron discharge may be used.

According to the sputtering apparatus 1 of the present example, a thin film having a target film thickness can be formed on a substrate by manufacturing a thin film thinner than the target film thickness by sputtering and repeating plasma processing. In this example, a thin film having an average film thickness of 0.01 to 1.5nm was formed by sputtering and plasma treatment, and this step was repeated to form a thin film having a film thickness of several to several hundred nm as a target value.

The main structural units of the sputtering apparatus 1 of this example are as follows: a vacuum vessel 11; a substrate holder 13 for holding the substrate on which the thin film is formed in the vacuum chamber 11; a motor 17 for driving the substrate holder 13; partition walls 12, 16; magnetron sputtering electrodes 21a, 21 b; an intermediate frequency ac power supply 23; a plasma generating device 61 for generating plasma. The partition wall 16 corresponds to a plasma convergence wall of the present invention, the plasma generating device 61 corresponds to a plasma generating unit of the present invention, and the substrate holder 13 and the motor 17 correspond to a substrate conveying unit of the present invention.

The vacuum vessel 11 is a stainless steel product commonly used in a known sputtering apparatus, and is a hollow member having a substantially rectangular parallelepiped shape. The shape of the vacuum vessel 11 may be a hollow cylindrical shape.

The substrate holder 13 is disposed substantially at the center in the vacuum chamber 11. The substrate holder 13 has a cylindrical shape, and holds a plurality of substrates (not shown) on the outer peripheral surface thereof. The substrate holder 13 may have a hollow polygonal column shape or a conical shape instead of the cylindrical shape. The substrate holder 13 is electrically insulated from the vacuum vessel 11. Thus, abnormal discharge of the substrate can be prevented. The substrate holder 13 is disposed in the vacuum chamber 11, and a central axis Z (see fig. 2) of the cylindrical direction is disposed in the vertical direction of the vacuum chamber 11. In a state where the vacuum state in the vacuum chamber 11 is maintained, the substrate holder 13 is driven to rotate around the central axis Z by a motor 17 provided at the upper portion of the vacuum chamber 11.

A plurality of substrates (not shown) are held on the outer peripheral surface of the substrate holder 13 in the following states: the plurality of substrates are arranged in a direction (vertical direction) along the center axis Z of the substrate holder 13 so as to be spaced apart from each other at a predetermined interval. In this example, the substrate is held on the substrate holder 13 in the following manner: the surface of the substrate on which the thin film is formed (hereinafter referred to as "film formation surface") faces in a direction perpendicular to the central axis Z of the substrate holder 13.

The partition walls 12 and 16 are erected from the inner wall surface of the vacuum chamber 11 toward the substrate holder 13. The partition walls 12 and 16 in this example are cylindrical, substantially rectangular parallelepiped, stainless steel members having a pair of surfaces that are open and face each other. The partition walls 12 and 16 are fixed between the side inner wall of the vacuum chamber 11 and the substrate holder 13 in a state of being erected from the side wall of the vacuum chamber 11 toward the substrate holder 13. At this time, the partition walls 12 and 16 are fixed as follows: the partition walls 12 and 16 are opened to the inner wall of the vacuum chamber 11 and to the substrate holder 13. Further, the end portions of the partition walls 12 and 16 on the substrate holder 13 side have a shape formed along the outer peripheral shape of the substrate holder 13.

A film formation processing region 20 for performing sputtering is surrounded by the inner wall surface of the vacuum chamber 11, the partition wall 12, and the outer peripheral surface of the substrate holder 13. A reaction processing region 60 is formed by surrounding the inner wall surface of the vacuum chamber 11, a plasma generating device 61 described later, the partition wall 16, and the outer peripheral surface of the substrate holder 13, and the reaction processing region 60 is used for generating plasma and performing plasma processing on a thin film on the substrate. In this example, the partition wall 16 is fixed at a position rotated approximately 90 degrees around the center axis Z of the substrate holder 13 from the position where the partition wall 12 is fixed to the vacuum chamber 11. Therefore, the film formation processing region 20 and the reaction processing region 60 are formed at positions rotated by 90 degrees with respect to the central axis Z of the substrate holder 13. Therefore, when the motor 17 drives the substrate holder 13 to rotate, the substrate held on the outer periphery of the substrate holder 13 is conveyed between a position facing the film formation processing region 20 and a position facing the reaction processing region 60.

A pipe for exhausting is connected to a position between the film formation processing region 20 and the reaction processing region 60 of the vacuum chamber 11, and the pipe is connected to a vacuum pump 15 for exhausting gas in the vacuum chamber 11. The vacuum pump 15 and a controller, not shown, are configured to adjust the degree of vacuum in the vacuum chamber 11.

A protective layer P made of Pyrolytic Boron Nitride (pyrolitic Boron Nitride) is coated on the wall surface of the partition wall 16 facing the reaction processing region 60. Further, a protective layer P made of thermally decomposed boron nitride is also applied to the inner wall surface of the vacuum chamber 11 at a portion facing the reaction processing region 60. The thermally decomposed boron nitride is coated on the partition wall 16 and the inner wall surface of the vacuum vessel 11 by a thermal decomposition method using a Chemical Vapor Deposition method (Chemical Vapor Deposition).

The film formation processing section 20 is connected to mass flow controllers 25 and 26 via pipes. The mass flow controller 25 is connected to a sputtering gas tank 27 for storing an inert gas. The mass flow controller 26 is connected to a reactive gas storage tank 28 that stores a reactive gas. The inert gas and the reactive gas are controlled by mass flow controllers 25 and 26 and introduced into the film formation processing region 20. The inert gas is, for example, argon gas. As the reactive gas, for example, oxygen gas, nitrogen gas, fluorine gas, ozone gas, or the like can be used.

In the film formation processing zone 20, magnetron sputtering electrodes 21a and 21b are arranged on the wall surface of the vacuum chamber 11, and the magnetron sputtering electrodes 21a and 21b are opposed to the outer peripheral surface of the substrate holder 13. The magnetron sputtering electrodes 21a and 21b are fixed to the vacuum chamber 11 at the ground potential by an insulating member not shown. The magnetron sputtering electrodes 21a and 21b are connected to a medium-frequency ac power supply 23 via a transformer 24, and are configured to apply an ac electric field. The medium frequency ac power supply 23 of this example can apply an ac electric field of 1k to 100 kHz. Targets 29a and 29b are held by the magnetron sputtering electrodes 21a and 21 b. The targets 29a and 29b have a flat plate shape, and surfaces of the targets 29a and 29b facing the outer peripheral surface of the substrate holder 13 are held in a direction perpendicular to the central axis Z of the substrate holder 13.

In addition, a plurality of film formation processing regions for performing sputtering may be provided, not only one. That is, as shown by the broken line in fig. 1, the vacuum chamber 11 may be provided with the film formation processing region 40 similar to the film formation processing region 20. For example, the partition wall 14 is provided in the vacuum chamber 11, and the film formation processing regions 40 can be formed at symmetrical positions with respect to the film formation processing regions 20 with the substrate holder 13 interposed therebetween. Magnetron sputtering electrodes 41a and 41b are disposed in the film formation processing region 40, similarly to the film formation processing region 20. The magnetron sputtering electrodes 41a and 41b are connected to a medium-frequency ac power supply 43 through a transformer 44, and are configured to apply an ac electric field. Targets 49a and 49b are held by magnetron sputtering electrodes 41a and 41 b. The film formation processing section 40 is connected to mass flow controllers 45 and 46 by pipes. The mass flow controller 45 is connected to a sputtering gas storage tank 47 for storing an inert gas. The mass flow controller 46 is connected to a reactive gas storage tank 48 that stores a reactive gas. A pipe for exhausting is connected to the vacuum chamber 11 at a position between the film formation processing zone 40 and the reaction processing zone 60, and the pipe is connected to a vacuum pump 15' for exhausting the gas in the vacuum chamber 11. The vacuum pump 15' may be common to the vacuum pump 15.

An opening is formed in an inner wall surface of the vacuum vessel 11 corresponding to the reaction processing region 60, and the opening is connected to a plasma generating device 61 as a plasma generating means. Further, to the reaction treatment section 60, as gas introducing means of the present invention, a pipe for introducing an inert gas in the inert gas holder 77 through the flow mass controller 75 or a pipe for introducing a reactive gas in the reactive gas holder 78 through the mass flow controller 76 is connected.

Fig. 3 is a schematic diagram illustrating the plasma generation device 61, and is a schematic diagram of the plasma generation device 61 as viewed from the front. In fig. 3, a matching box 67 and a high frequency power supply 69 are also shown.

The plasma generation device 61 includes: dielectric wall 63 formed in a plate shape with a dielectric; spiral antennas 65a and 65b are formed on the same plane; a wire 66 for connecting the antennas 65a, 65b to a high-frequency power supply 69; and a fixing member 68 for fixing the antennas 65a, 65b to the dielectric wall 63. The antenna 65a corresponds to a first antenna of the present invention, the antenna 65b corresponds to a second antenna of the present invention, and the fixing member 68 corresponds to an antenna fixing unit of the present invention.

The dielectric walls 63 of the present example are formed of quartz. In addition, the dielectric wall 63 may be made of Al instead of quartz₂O₃And the like. The dielectric wall 63 is provided at a position to close an opening formed in the inner wall of the vacuum chamber 11 corresponding to the reaction processing region 60 so as to be sandwiched between the flange 11a formed in the vacuum chamber 11 and the rectangular frame-shaped lid 11 b. The antennas 65a and 65b are fixed to positions corresponding to the dielectric walls 63 outside the vacuum chamber 11 by fixing members 68 in a state where the spiral surfaces face the inside of the vacuum chamber 11 and are vertically adjacent to each other (see fig. 2 and 3). Therefore, by rotating the substrate holder 13 around the central axis Z by the motor 17, the substrate held on the outer periphery of the substrate holder 13 is conveyed so that the film formation surface of the substrate faces the spiral surfaces of the antennas 65a and 65 b. That is, in this example, since the antenna 65a and the antenna 65b are fixed in a state of being adjacent to each other in the vertical direction, the antenna 65a and the antenna 65b are fixed in a state of being adjacent to each other in a direction (vertical direction in this example) intersecting the substrate conveyance direction.

The fixing member 68 of this example is constituted by fixing plates 68a, 68b and bolts 68c, 68 d. The antenna 65a is held between the fixing plate 68a and the dielectric wall 63, the antenna 65b is held between the fixing plate 68b and the dielectric wall 63, and the fixing plates 68a and 68b are fastened to the cover 11b by bolts 68c and 68d, whereby the antennas 65a and 65b are fixed.

On the tip of the wire 66 from the high-frequency power source to the antennas 65a, 65b, the antenna 65a and the antenna 65b are connected in parallel with respect to the high-frequency power source 69. The antennas 65a, 65b are connected to a high-frequency power supply 69 via a matching box 67 that houses a matching circuit. As shown in fig. 3, variable capacitors 67a and 67b are provided in the matching box 67. In this example, since the antenna 65b is connected in parallel with the antenna 65a, the antenna 65b functions as all or a part of the matching coil 167c in the conventional matching circuit (see fig. 10). Therefore, power loss in the matching box can be reduced, and the power supplied from the high-frequency power supply 69 can be effectively applied to the generation of plasma by the antennas 65a and 65 b. In addition, impedance matching is easily achieved.

At the portion connected to the tip of the lead 66, slack portions 66a, 66b are provided at the portion connecting the antenna 65a and the antenna 65b, so that the distance D between the antenna 65a and the antenna 65b can be adjusted. The slack portions 66a and 66b correspond to the position adjustment means of the present invention. In the sputtering apparatus 1 of the present example, when the antennas 65a and 65b are fixed by the fixing member 68, the distance D between the antennas 65a and 65b in the vertical direction can be adjusted by extending and contracting the slack portions 66a and 66 b. That is, the distance D can be adjusted by changing the position where the fixing plates 68a, 68b and the dielectric wall 63 sandwich the antennas 65a, 65 b.

Fig. 4 is a cross-sectional view of the antenna 65 a. The antenna 65a of the present example is constituted by: round tubular body 65a made of copper₁(ii) a Coating layer 65a formed of silver for coating the surface of the main body₂. In order to reduce the impedance of the antenna 65a, it is preferable to form the antenna 65a with a material having low resistance. Therefore, the circular tube-shaped body 65a is formed of copper which is inexpensive, easy to process, and low in electric resistance, utilizing the characteristic that the high-frequency current concentrates on the surface of the antenna₁The main body part 65a is coated with silver having a lower resistance than copper₁Forming a coating layer 65a on the outer surface of the substrate₂. With this configuration, the impedance of the antennas 65a and 65b to a high frequency is reduced, and a current is efficiently supplied to the antenna 65a, thereby improving the efficiency of generating plasma. The antenna 65b has a main body 65b made of copper, similarly to the antenna 65a₁And a coating layer 65b formed of silver₂. Of course, the cross-sectional sizes (thicknesses) of the antennas 65a and 65b may be changed. In this example, the slack portions 66a and 66b are also formed of copper in a circular tube shape, and silver is applied to the portionsOn the surface thereof.

In the plasma generating apparatus 61 of this example, the distance D between the antennas 65a and 65b in the vertical direction, the diameter Ra of the antenna 65a, the diameter Rb of the antenna 65b, and the like are adjusted, the antennas 65a and 65b are fixed, and the reactive gas in the reactive gas cylinder 78 is introduced into the reaction processing region 60, which is kept in a vacuum of about 0.1Pa to 10Pa, through the mass flow controller 75. Then, by applying a voltage of 13.56MHz from the high-frequency power supply 69 to the antennas 65a and 65b, plasma of the reactive gas is generated in a desired distribution in the reaction processing region 60, and plasma processing can be performed on the substrate placed on the substrate holder 13.

In this example, since there are two antennas 65a, 65b and slack portions 66a, 66b connected in parallel, power loss in the matching circuit inside the matching box 67 can be reduced, and impedance matching is easily obtained, and plasma processing can be efficiently performed in a wide range, as compared with the case where one antenna is increased.

In addition, the main body 65a of the circular tube antennas 65a and 65b is formed of copper which is inexpensive, easy to process, and has low electric resistance₁、65b₁And the coating layer 65a is formed by silver which is a material having lower resistance than copper₂、65b₂Therefore, the high-frequency impedance of the antennas 65a and 65b can be reduced, and effective plasma processing with reduced power loss can be performed.

In this example, the distribution of plasma to the substrate placed on the substrate holder 13 can be adjusted by adjusting the vertical distance D between the antennas 65a and 65 b. Further, since the diameter Ra of the antenna 65a, the diameter Rb of the antenna 65b, the thicknesses of the antennas 65a and 65b, and the like can be independently changed, the distribution of plasma can be adjusted by adjusting the diameter Ra of the antenna 65a, the diameter Rb of the antenna 65b, the thickness, and the like. In this example, as shown in fig. 3, the antennas 65a and 65b have an overall shape formed by large and small semicircles, but the overall shape of the antennas 65a and 65b may be changed to a rectangular shape or the like, and the distribution of plasma may be adjusted.

In particular, since the antennas 65a and 65b are arranged in the direction intersecting the substrate conveying direction and the interval between them can be adjusted, when it is necessary to perform plasma processing in the direction intersecting the substrate conveying direction and over a wide range, the density distribution of plasma can be easily adjusted. For example, when plasma processing is performed using the rotary (carousel) type sputtering apparatus 1 of the present example, a difference may occur in film thickness between a thin film located above the substrate holder 13 and a thin film located in the middle depending on the arrangement of the substrate on the substrate holder 13, sputtering conditions, and the like. Even in this case, when the plasma generation device 61 of the present example is used, there is an advantage that the density distribution of plasma can be appropriately adjusted according to the difference in film thickness.

In this example, as described above, by applying thermally decomposed boron nitride to the wall surface of the partition wall 16 facing the reaction processing region 60 and the portion of the inner wall surface of the vacuum chamber 11 facing the reaction processing region 60, a high density of radicals in the reaction processing region 60 can be maintained, and more radicals can be brought into contact with the thin film on the substrate, thereby achieving high efficiency of plasma processing. That is, by applying the thermally decomposed boron nitride having stable chemical properties to the partition wall 16 and the inner wall surface of the vacuum chamber 11, it is possible to suppress the radicals generated in the reaction processing region 60 by the plasma generator 61 or the radicals in an excited state from being lost by the reaction with the partition wall 16 and the inner wall surface of the vacuum chamber 11. In addition, the direction of radicals generated in the reaction processing region 60 toward the substrate holder 13 can be controlled by the partition wall 16.

Next, as a method of plasma processing using the sputtering apparatus 1, for example, the following method is possible: for incomplete silicon oxide (SiO) formed on a substrate by sputtering_x1(x1<2) Is subjected to plasma treatment to form silicon oxide (SiO) which is further oxidized than the incomplete silicon oxide_x2(x1<x2≤2)) A film of (2). In addition, incomplete silica is lacking as SiO silicon oxide₂Incomplete silicon oxide SiO of oxygen as constituent element_x(x<2)。

First, the substrate and the targets 29a and 29b are disposed in the sputtering apparatus 1. The substrate is held by the substrate holder 13, and the targets 29a and 29b are held by the magnetron sputtering electrodes 21a and 21b, respectively. Silicon (Si) is used as a material of the targets 29a and 29 b.

Next, the pressure in the vacuum chamber 11 is reduced to a predetermined pressure, and the motor 17 is operated to rotate the substrate holder 13. After the pressure in the vacuum chamber 11 is stabilized, the pressure in the film formation processing region 20 is adjusted to 0.1 to 1.3 Pa.

Then, while the flow rates are adjusted by the mass flow controllers 25 and 26, argon gas as an inert gas for sputtering and oxygen gas as a reactive gas are introduced into the film formation processing region 20 from the sputtering gas cylinder 27 and the reactive gas cylinder 28, and then the gas medium for sputtering in the film formation processing region 20 is adjusted.

Then, an alternating current voltage having a frequency of 1 to 100KHz is applied to the magnetron sputtering electrodes 21a and 21b from the medium-frequency alternating current power supply 23 through the transformer 24, so that an alternating current electric field is formed between the targets 29a and 29 b. Thus, at a certain time, the target 29a is a cathode (negative electrode), and at this time, the target 29b is necessarily an anode (positive electrode). At the next moment, the direction of the alternating current changes, this time with the target 29b being the cathode (negative electrode) and the target 29a being the anode (positive electrode). Thus, the pair of targets 29a and 29b alternately serve as an anode and a cathode, thereby forming plasma and sputtering the targets on the cathode.

In the sputtering process, silicon oxide (SiO) having non-conductivity or low conductivity may adhere to the anode_x(x.ltoreq.2)), but when the anode is converted into a cathode by an alternating current electric field, these silicon oxides (SiO)_x(x is less than or equal to 2)) is sputtered, and the surface of the target material is changed into the original clean state.

And, byBy alternately changing the pair of targets 29a and 29b into the anode and the cathode repeatedly, a stable anode potential state can be obtained at all times, and a change in plasma potential (which is substantially equal to the normal anode potential) can be prevented, so that silicon or incomplete silicon oxide (SiO) can be stably formed on the film formation surface of the substrate_x1(x1<2) A film of (b).

In addition, by adjusting the flow rate of oxygen gas introduced into the film formation processing region 20 or by controlling the rotation rate of the substrate holder 13, the thin film formed in the film formation processing region 20 can be made of silicon (Si) or silicon oxide (SiO)₂) Or incomplete silicon oxide (SiO)_x1(x1<2) ) is prepared.

In the film formation processing region 20, a film formed of silicon or incomplete silicon oxide (SiO) is formed on the film formation surface of the substrate_x1(x1<2) After the thin film is formed, the substrate holder 13 is driven to rotate, whereby the substrate can be transported from a position facing the film formation processing region 20 to a position facing the reaction processing region 60.

Oxygen gas is introduced from the reactive gas holder 78 into the reaction processing region 60, and argon gas as an inert gas is introduced from the inert gas holder 77 into the reaction processing region 60. Then, a high-frequency voltage of 13.56MHz is applied to the antennas 65a, 65b, and plasma is generated in the reaction processing region 60 by the plasma generating device 61. The pressure in the reaction treatment zone 60 is maintained at 0.7Pa to 1 Pa.

Then, the substrate holder 13 is rotated to form a layer of silicon or incomplete silicon oxide (SiOx)₁(x1<2) When a substrate of a thin film is carried to a position facing the reaction processing region 60, plasma treatment is performed in the reaction processing region 60 to form a thin film of silicon or incomplete silicon oxide (SiO)_x1(x1<2) A step of causing an oxidation reaction of the thin film. That is, silicon or incomplete silicon oxide (SiO) is generated by plasma of oxygen gas generated in the reaction treatment zone 60 by the plasma generating means 61_x1(x1<2) Undergoes an oxidation reaction to convert into incomplete silicon oxide (SiO) of a desired composition_x2(x1<x2<2) Or silicon oxide.

In this example, through the above-described steps, silicon oxide (SiO) having a desired composition can be produced_x(x.ltoreq.2)) film. Further, by repeating the above steps, a thin film having a desired thickness can be produced by laminating thin films.

In particular, in this example, not only oxygen gas but also argon gas, which is an inert gas, is introduced into the reaction processing region, so that the density of radicals of the reactive gas in the plasma can be increased. This effect is shown in fig. 5 and 6.

FIG. 5 is a graph showing the ratio of oxygen atoms to oxygen ions in the plasma generated in the reaction treatment region 60, and shows the experimental results comparing the case where only oxygen gas is introduced into the reaction treatment region 60 with the case where oxygen gas and argon gas are introduced in a mixed manner. In fig. 5, the horizontal axis represents power applied by the high-frequency power source 69, and the vertical axis represents the emission intensity ratio. The Emission intensity ratio is obtained by measuring the Emission intensities of oxygen radicals and oxygen ions in an excited state present in plasma by an Optical Emission Spectroscopy (Optical Emission Spectroscopy). As can be seen from fig. 5, when oxygen gas and argon gas were mixed and introduced (when oxygen gas was introduced at 110sccm and argon gas was introduced at 40 sccm), the oxygen radical density in the excited state was higher than that when oxygen gas was introduced at 150sccm into the reaction processing region 60. The flow rate of sccm as a unit of flow rate is represented by the flow rate per minute at 0 ℃ and 1atm, and cm³And/min is equal.

Fig. 6 shows the results of an experiment in which the emission intensities of oxygen radicals and oxygen ions in an excited state existing in plasma are measured by a luminescence spectroscopy method when oxygen and argon are mixed and introduced into the reaction treatment region 60. In fig. 6, the horizontal axis represents power applied by the high-frequency power source 69, and the vertical axis represents the emission intensity ratio.

In this example, as described above, thermally decomposed boron nitride is applied to partition wall 16 and vacuum chamber 11, and therefore, a high density of oxygen radicals in the plasma in reaction processing region 60 can be maintained. This effect is shown in fig. 7.

Fig. 7 is a graph showing the flow density of oxygen radicals in the plasma generated in the reaction processing region 60, and shows an example of experimental results comparing the case where thermally decomposed boron nitride (PBN) is applied to the partition wall 16 and the vacuum chamber 11 with the case where it is not applied. In the present experimental example, as a case where the partition wall 16 and the vacuum vessel 11 are coated with the thermally decomposed boron nitride, the thermally decomposed boron nitride is coated on a side of the partition wall 16 facing the reaction processing region 60 side, and on a portion of the inner wall surface of the vacuum vessel 11 facing the reaction processing region 60 surrounded by the partition wall 16.

In fig. 7, the horizontal axis represents the flow rate of oxygen introduced into the reaction processing region 60, and the vertical axis represents the flow rate density of oxygen radicals in the plasma generated in the reaction processing region 60. The value of the flux density of the oxygen radical indicated by the vertical axis of fig. 7 indicates the value of the absolute flux density. The absolute flow density value can be determined from the degree of oxidation of the silver thin film. That is, the substrate on which the silver thin film is formed is held by the substrate holder 13, the degree of oxidation of silver is measured from the change in weight of the thin film before and after the plasma treatment in the reaction treatment region 60, and the value of the absolute flow density is calculated from the degree of oxidation. As is clear from fig. 7, when thermally decomposed boron nitride is applied to partition wall 16 and vacuum chamber 11, the flux density of oxygen radicals is high.

As described above, for the production of silicon oxide (SiO) having a desired composition_x(x.ltoreq.2)) thin film, but a thin film having a structure in which thin films having different compositions are repeatedly stacked can be formed by providing not only a film formation processing region in which sputtering is performed at one location but also a plurality of locations in which sputtering is performed. For example, as described above, the film formation processing region 40 is provided in the sputtering apparatus 1, and niobium (Nb) is used as the targets 49a, 49 b. Niobium oxide (NbO) having a desired composition is formed on the silicon oxide thin film by the same method as that for forming the silicon oxide thin film_y(y<2.5)) films. Further, the following steps are repeatedly performed: sputtering in the film formation processing region 20; in the reaction treatment zone 60, etcOxidation of the plasma treatment; sputtering in the film formation processing region 40; the oxidation by the plasma treatment in the reaction treatment region 60 can form a repeated lamination of silicon oxide (SiO) having a desired composition_x(x.ltoreq.2)) thin film and niobium oxide (NbO)_y(y.ltoreq.2.5)) a film.

In particular, in this example, by using the sputtering apparatus 1 having the plasma generating device 61, a high-performance thin film having a high density and a high quality can be manufactured. Fig. 8 and 9 show this effect.

FIGS. 8 and 9 show the formation of silicon oxide (SiO)₂) And niobium oxide (Nb)₂O₅) A graph of film transmittance in the case of the multilayer film of (3). Fig. 8 shows the results of an experiment for forming a multilayer thin film of niobium oxide and silicon oxide using the conventional plasma generator 161 shown in fig. 10 in place of the plasma generator 61 of the sputtering apparatus 1, and fig. 9 shows the results of an experiment for forming a multilayer thin film of niobium oxide and silicon oxide using the plasma generator 61 of this example. In fig. 8 and 9, the horizontal axis represents the measurement wavelength, and the vertical axis represents the transmittance.

In the case of using the conventional plasma generator 161, a voltage of 5.5kW was applied from the high-frequency power supply 169 to form SiO at a rate of 0.3nm/s₂Film formation of Nb at a rate of 0.2nm/s₂O₅And (4) film forming. And, SiO₂Layer and Nb₂O₅The layers were laminated in this order 17 times repeatedly to produce a thin film having a total physical film thickness of 940 nm. As a result, the prepared material had an attenuation coefficient k of 100X 10 at a measurement wavelength of 650nm^-5The film of (2) (FIG. 8).

On the other hand, in the case of using the sputtering apparatus 1 having the plasma generating apparatus 61 of the present example, a voltage of 4.0kW was applied by the high-frequency power source 69, and SiO was caused to flow at a rate of 0.5nm/s₂Film formation of Nb at a rate of 0.4nm/s₂O₅And (4) film forming. Then SiO₂Layer and Nb₂O₅The layers were sequentially stacked and repeated 38 times to produce a thin film having a total physical film thickness of 3242 nm. As a result, the measurement wavelength was determinedAn attenuation coefficient k of 5X 10 at 650nm^-5The film of (2) (FIG. 9).

As described above, it is understood from the results of forming a multilayer thin film of silicon oxide and niobium oxide using the sputtering apparatus 1 including the plasma generation apparatus 61 of the present example that when a thin film is formed by performing plasma processing using the sputtering apparatus 1 of the present example, a good thin film having a small attenuation coefficient (absorption coefficient) can be formed.

When the optical constant (complex refractive index) is N and the refractive index is N, the value of the attenuation coefficient k is expressed by a relationship of N + ik.

The embodiments described above may be modified to the cases shown in (a) to (j), for example. Further, the combinations of (a) to (j) may be appropriately modified.

(a) In the above-described embodiment, the inductively coupled (flat plate type) plasma generating means shown in fig. 1 to 3, in which the antennas 65a and 65b are fixed to the plate-shaped dielectric wall 63, is used as the plasma generating means, but the present invention can be applied to a thin film forming apparatus having other types of plasma generating means. That is, even in the case of using a thin film forming apparatus having a plasma generating means of a type other than the induction bonding type (flat plate type), by applying thermally decomposed boron nitride to the inner wall surface of the vacuum chamber and the plasma converging wall, it is possible to suppress the radicals in the plasma generated by the plasma generating means or the radicals in the excited state from being lost by the reaction with the inner wall surface of the vacuum chamber and the wall surface of the plasma converging wall, as in the above-described embodiment. Examples of the plasma generating means other than the inductively coupled type (flat plate type) include various plasma generating means such as a parallel flat plate type (diode discharge type), an ecr (electron cycle resonance) type, a magnetron type, a helical waveform type, and an inductively coupled type (cylindrical type).

(b) In the above-described embodiment, the sputtering apparatus is described as an example of the thin film forming apparatus, but the present invention can be applied to other types of thin film forming apparatuses. Examples of the thin film forming apparatus include an etching apparatus that performs etching using plasma, and a CVD apparatus that performs CVD using plasma. Further, the present invention can be applied to a surface treatment apparatus for performing surface treatment of plastic by using plasma.

(c) In the above embodiment, the so-called chuck unit type sputtering apparatus is used, but the present invention is not limited to this. The present invention can be applied to other sputtering apparatuses in which a substrate is transported so as to face a region where plasma is generated.

(d) In the above embodiment, the protective layer P made of thermally decomposed boron nitride is formed on the wall surface of the partition wall 16 facing the reaction processing region 60 and on the portion of the inner wall surface of the vacuum vessel 11 facing the reaction processing region 60, and the protective layer P made of thermally decomposed boron nitride may be formed on other portions. For example, not only the wall surface of the partition wall 16 facing the reaction processing region 60 but also other portions of the partition wall 16 may be coated with thermally decomposed boron nitride. This can prevent the reduction of radicals due to the reaction with the partition walls 16 to the maximum. In addition, for example, not only the portion of the inner wall surface of the vacuum chamber 11 facing the reaction processing region 60, but also other portions of the inner wall surface of the vacuum chamber 11, for example, the entire inner wall surface, may be coated with thermally decomposed boron nitride. This can prevent the radicals from reacting with the inner wall surface of the vacuum chamber 11 to a maximum extent and reducing. The partition wall 12 may be coated with thermally decomposable boron nitride.

(e) In the above embodiment, the case where thermally decomposed boron nitride is applied to the wall surface of the partition wall 16 facing the reaction treatment region 60 and the inner wall surface of the vacuum vessel 11 was described, but aluminum oxide (Al) is applied₂O₃) Silicon oxide (SiO)₂) Boron Nitride (BN), which can suppress radicals in the plasma generated by the plasma generating means or radicals in an excited state from being lost by reaction with the inner wall surface of the vacuum chamber 11 or the wall surface of the plasma converging wall.

(f) In the above embodiment, the antennas 65a and 65b are fixed by sandwiching the antennas 65a and 65b between the fixing plates 68a and 68b and the dielectric wall 63 and fixing the fixing plates 68a and 68b to the lid 11b with the bolts 68c and 68D, and it is important to use other methods as long as the antennas 65a and 65b can be fixed by adjusting the distance D. For example, the antenna 65a is fixed to the fixing plate 68a, the antenna 65b is fixed to the fixing plate 68b, and then, the lid 11b is provided with long holes for vertically sliding the bolts 68c and 68 d. Then, the fixing positions of the fixing plates 68a and 68b in the vertical direction with respect to the lid 11b can also be determined by selecting the interval D by sliding the fixing plates 68a and 68b in the vertical direction and tightening the bolts 68c and 68D at the desired interval D.

(g) In the above embodiment, the main body portion 65a of the antenna 65a is formed of copper₁A coating layer 65a formed of silver₂However, the main body 65a is mainly made of a material which is inexpensive, easy to process, and has low electric resistance₁A resistance ratio main body part 65a₁The material having low density forms the current-concentrated coating layer 65a₂That is, other material combinations are also possible. For example, the main body portion 65a may be formed of aluminum or an aluminum-copper alloy₁Alternatively, the coating layer 65a may be formed of copper or gold₂. Main body 65b of antenna 65b₁And a coating layer 65b₂The same changes can be made. In addition, the antenna 65a and the antenna 65b may be formed of different materials.

(h) In the above embodiment, oxygen is introduced as the reactive gas into the reaction treatment zone 60, but in addition to this, ozone or nitrous oxide (N) may be introduced₂O), an oxidizing gas such as nitrogen, a nitriding gas such as nitrogen, a carbonizing gas such as methane, fluorine, carbon tetrafluoride (CF)₄) Such as a fluorinated gas, to apply the present invention to plasma treatment other than oxidation treatment.

(i) In the above embodiment, silicon is used as the material of the targets 29a and 29b, and niobium is used as the material of the targets 49a and 49b, but the present invention is not limited thereto, and oxides of the above substances may be used. In addition, aluminum (Al) and titanium (Ti) can be usedMetals such as (Ti), zirconium (Zr), tin (Sn), chromium (Cr), thallium (T), tellurium (Te), iron (Fe), magnesium (Mg), hafnium (Hf), nickel-chromium (Ni-Cr), and indium-tin (In-Sn). In addition, compounds of these metals, for example, Al, may also be used₂O₃、TiO₂、ZrO₂、Ta₂O₅、HfO₂And the like. Of course, the materials of the targets 29a, 29b, 49a, and 49b may be all the same.

In the case of using these targets, by plasma treatment in the reaction treatment region 60, it is possible to make: al (Al)₂O₃、TiO₂、ZrO₂、Ta2O₅、SiO₂、Nb₂O₅、HfO₂、MgF₂An optical film or an insulating film, a conductive film of ITO or the like, Fe₂O₃Etc., and a superhard film of TiN, CrN, TiC, etc. TiO 2₂、ZrO₂、SiO₂、Nb₂O₅、Ta₂O₅The insulating compound has a very low sputtering rate and a low productivity as compared with metals (Ti, Zr, and Si), and thus the plasma treatment using the thin film forming apparatus of the present invention is particularly effective.

(j) In the above embodiment, the target 29a and the target 29b are made of the same material, and the target 49a and the target 49b are made of the same material, but they may be made of different materials. As described above, when the same metal target is used, an incomplete reactant of a single metal is formed on the substrate by sputtering, and when different kinds of metal targets are used, an incomplete reactant of an alloy is formed on the substrate.

As inventions other than those described in the claims that can be understood from the above-described embodiments, there are, for example, the following thin film forming methods.

Namely, a thin film forming method is considered: a method for forming a thin film by plasma processing a thin film using a thin film forming apparatus in which a pyrolytic boron nitride is coated on a plasma-converging wall that is provided upright from an inner wall surface of a vacuum chamber and faces a region in which plasma is generated in the vacuum chamber, the method comprising: mixing a reactive gas and an inert gas and introducing the mixture into a region where the plasma is generated; a plasma of the above reactive gas is generated.

In the thin film forming method, by using a vacuum chamber in which a pyrolytic boron nitride is coated on a plasma converging wall which is provided upright from an inner wall surface of the vacuum chamber and faces a region where plasma is generated, it is possible to suppress radicals of generated plasma or radicals in an excited state from being lost by reaction with the wall surface of the plasma converging wall, and to perform efficient plasma processing. Further, by mixing the reactive gas and the inert gas and introducing them into the region where the plasma is generated, the radical density of the reactive gas in the plasma can be increased, and efficient plasma processing can be performed. In addition, by using a vacuum vessel having a plasma-converging wall, the distribution of plasma can be controlled.

In the thin film forming apparatus and the thin film forming method described above, the plasma processing can be efficiently performed in a wide range.

Claims (3)

1. A thin film forming apparatus includes: a vacuum container whose inside is maintained to be vacuum; a gas introduction unit for introducing a reactive gas into the vacuum vessel; a plasma generating means for generating plasma of the reactive gas in the vacuum chamber,

the plasma generation unit includes: a dielectric wall provided on an outer wall of the vacuum chamber; the first antenna and the second antenna are vortex-shaped; a wire for connecting the first antenna and the second antenna to a high frequency power source,

the thin film forming apparatus includes an antenna fixing unit for fixing the first antenna and the second antenna at positions corresponding to the dielectric wall outside the vacuum chamber,

the first antenna and the second antenna are connected in parallel to the high-frequency power supply,

a position adjusting unit for adjusting a distance between the first antenna and the second antenna is provided at a portion connected to the lead at a portion where the first antenna and the second antenna are connected.

2. The thin film forming apparatus according to claim 1, wherein the vacuum chamber includes a substrate carrying unit for carrying a substrate,

the substrate carrying unit carries the substrate in a manner that the substrate is opposite to the surface of the first antenna and the second antenna forming a spiral shape,

the first antenna and the second antenna are fixed in a state of being adjacent to each other in a direction intersecting a direction in which the substrate is conveyed by the substrate conveying unit.

3. The film forming apparatus according to claim 1, wherein the first antenna and the second antenna are constituted by: a circular tubular body portion formed from a first material; the coating layer on the surface of the main body is coated with a second material having a lower resistance than the first material.