JP4823293B2 - Film forming method and film forming apparatus - Google Patents

Description

  The present invention relates to a film forming method and a film forming apparatus.

A vapor deposition apparatus that performs densification by irradiating ions to a vapor deposition layer deposited on a substrate when a film forming material is evaporated toward a substrate surface in a vacuum vessel, that is, an ion assist vapor deposition apparatus is known ( Patent Documents 1 and 2).
JP-A-10-123301 JP 2007-248828 A

  However, in the above-described conventional method, the ion beam is radiated from the ion source to all the substrates to which the film forming material is supplied from the vapor deposition source, so that the ion assist effect by the ion beam irradiated from the ion source is achieved. The film quality of the thin film formed on the substrate was not sufficient. Therefore, development of a technique capable of obtaining a higher ion assist effect has been desired.

  The problem to be solved by the invention is to provide a film forming method and a film forming apparatus capable of obtaining a higher ion assist effect.

  The present invention solves the above problems by the following means. In the following solution means, reference numerals corresponding to the drawings showing the embodiments of the invention will be attached and described. However, the reference numerals are only for facilitating the understanding of the invention and are not intended to limit the invention. Absent.

  The film forming method according to the present invention supplies the film forming material to the rotating substrate (14) held by the substrate holding means (12) and provides an assist effect by irradiating ions with the substrate ( 14) is a film forming method for depositing a thin film on the surface, where T1 is the supply time of the film forming material to the substrate (14), and T2 is the ion irradiation time to the substrate (14). It is characterized by irradiating with ions.

  In the above invention, ions can be irradiated so that T2 ≦ ((1/2) · T1).

  In the above invention, when the deposition material supply area to the substrate holding means (12) is A1, and the ion irradiation area to the substrate holding means (12) is A2, ions are irradiated so that A2 <A1. Can do.

  In the above invention, when the supply region of the film forming material to the substrate holding means (12) is A1, and the ion irradiation region to the substrate holding means (12) is A2, A2 ≦ ((1/2) · A1) It is possible to irradiate with ions.

  In the above invention, the ion irradiation region can be a region surrounded by a vertically long closed curve along the moving direction of the substrate (14).

  In the above invention, ions having an acceleration voltage of 50 to 1200 V can be used.

  In the above invention, ions having an irradiation ion current of 50 to 1000 mA can be used.

  In the above invention, ions containing at least oxygen can be used.

  The film forming apparatus according to the present invention is rotatably arranged in a vacuum vessel (10), and a substrate holding means (12) for holding the substrate (14) and a substrate held by the substrate holding means (12). A film forming material (34) for supplying a film forming material to (14) and depositing it on the surface of the substrate (14), and a portion of the substrate (14) can be irradiated with ions partially. The film formation assist means (38) is provided.

  In the above invention, the film formation assist means (38) is arranged so that ions can be irradiated to less than half of all the substrates (14) held by the substrate holding means (12), and the inside of the vacuum vessel (10). It may be arranged.

  In the above invention, the substrate holding means (12) is further rotated, and the film formation assisting means (38) is formed from the film formation assisting means (38) with respect to the axis of rotation of the substrate holding means (12). The axis of irradiation with ions may be disposed inside the vacuum vessel (10) so as to have an angle of 6 ° or more and 70 ° or less.

  In the above invention, the film formation assist means (38) may be disposed on the side surface side of the vacuum vessel (10).

  In the above invention, the film formation assist means (38) may be arranged such that the distance from the substrate (14) to the film formation assist means (38) is equal to or less than the mean free path.

  In the said invention, the film-forming assistance means (38) may be attached to the side surface of the vacuum vessel (10) through the support means (44) which can adjust an attachment angle at least.

  In the above invention, the film forming apparatus further includes second film forming assisting means (40) for irradiating the substrate (14) with electrons, and the second film forming assisting means (40) includes the film forming assisting means (38) and It may be provided in an arrangement separated by a predetermined distance.

  In the above invention, the substrate holding means (12) has a flat plate shape or a dome shape, and a through hole penetrating from one surface to the other surface is formed, and the substrate (14) closes the through hole. It may be held by the substrate holding means (12).

  In the above-mentioned invention, a heating means (53) for heating the substrate (14) and the substrate holding means (12) may further be provided.

  According to the above invention, since the ions are irradiated so that the irradiation time T2 of ions to the substrate is shorter than the supply time T1 of the film forming material to the substrate, the time when the ions are not irradiated to each substrate is secured. The While the ions are not irradiated, the molecules of the film forming material whose surface is migrated by the irradiation of the ions can be stopped at a stable position on the substrate. Even if the film deposition material molecules stationary at the stable site are irradiated again with ions, the stationary film deposition material molecules will not move from the stable site, resulting in a dense and high-quality thin film. Become. That is, a higher ion assist effect can be obtained.

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

<Film deposition system>
As shown in FIG. 1, a film forming apparatus 1 according to this embodiment is an ion-assisted vapor deposition apparatus capable of performing film forming processing while irradiating a substrate with an ion beam (gas ions) from an ion gun. A vacuum vessel 10 is included.

The vacuum container 10 is a stainless steel container having a generally cylindrical shape that is usually used in a known film forming apparatus, and is set at a ground potential. The vacuum vessel 10 is provided with an exhaust port (not shown; right side in FIG. 1 in the present embodiment), and a vacuum pump (not shown) is connected through the exhaust port. By operating the vacuum pump, the inside of the vacuum vessel 10 is evacuated to a predetermined pressure (for example, about 10 ^{−4 to} 3 × 10 ⁻² Pa). The vacuum vessel 10 is formed with a gas introduction pipe (not shown) for introducing a gas therein. A load lock chamber (not shown) may be connected to the vacuum vessel 10 via a door (not shown. In the present embodiment, the left side as viewed in FIG. 1). When the load lock chamber is provided, the substrate 14 can be loaded and unloaded while the vacuum state in the vacuum vessel 10 is maintained.

  A substrate holder 12 is held above the inside of the vacuum vessel 10. The substrate holder 12 (base body holding means) is a stainless steel member formed in a dome shape that is rotatably held around a vertical axis, and is an output shaft (not shown, rotating means) of a motor (not shown, rotating means). ).

  A plurality of substrates 14 are supported on the lower surface of the substrate holder 12 during film formation described later. In addition, an opening is provided in the center of the substrate holder 12 of the present embodiment, and a crystal monitor 50 is disposed here. The crystal monitor 50 detects the physical film thickness formed on the surface of the substrate 14 by the film thickness detector 51 from the change in the resonance frequency caused by the deposition material adhering to the surface. The film thickness detection result is sent to the controller 52.

  An electric heater 53 (heating means) is disposed above the inside of the vacuum vessel 10 so as to wrap the substrate holder 12 from above. The temperature of the substrate holder 12 is detected by a temperature sensor 54 such as a thermocouple, and the result is sent to the controller 52.

  Based on the output from the film thickness detector 51, the controller 52 controls the open / closed state of a shutter 34a of the vapor deposition source 34 and the shutter 38a of the ion source 38, which will be described later, so that the film thickness of the thin film formed on the substrate 14 is appropriately set. To control. Further, the controller 52 controls the electric heater 53 based on the output from the temperature sensor 54 and appropriately manages the temperature of the substrate 14.

A vapor deposition source 34 is disposed below the inside of the vacuum vessel 10. In this embodiment, the vapor deposition source 34 (film forming means) is an evaporation source that heats a film forming material such as a high refractive index substance or a low refractive index substance and emits it toward the substrate 14 by an electron beam heating method. . The evaporation source 34 includes a crucible (boat) 34b provided with a depression for placing a film forming material thereon, an electron gun 34c for irradiating the film forming material with an electron beam (e ⁻ ) and evaporating the electron beam 34e, and a crucible 34b. And a shutter 34a provided so as to be able to be opened and closed at a position where the film forming material directed from the substrate 14 to the substrate 14 is blocked. The shutter 34a is appropriately controlled to open and close according to a command from the controller 52. When the film forming material is placed on the crucible 34b, electric power is supplied to the electron gun 34c by the electron gun power supply 34d, an electron beam is generated from the electron gun 34c, and the film forming material is irradiated with the electron beam. Evaporates when heated. In this state, when the shutter 34 a is released in response to a command from the controller 52, the film forming material evaporated from the crucible 34 b moves inside the vacuum container 10 toward the substrate 14 and adheres to the surface of the substrate 14.

  The evaporation source 34 is not limited to the electron beam heating method, and may be a resistance heating method evaporation source such as a direct heating method or an indirect heating method. In the direct heating method, an electrode is attached to a metal boat and an electric current is passed, and the metal boat is directly heated to use the boat itself as a resistance heater, and the film forming material placed therein is heated. The indirect heating method is a method in which a boat is not a direct heat source, but is heated by passing a current through a heating device provided separately from the boat, for example, a vapor deposition filament made of a rare metal such as a transition metal. When the evaporation source 34 is a resistance heating method, the film forming material is heated by a heating device provided separately from the boat itself or the boat while the film forming material is placed on the crucible 34b, and the shutter 34a is moved in this state. When opened, the film forming material evaporated from the crucible 34 b moves inside the vacuum container 10 toward the substrate 14 and adheres to the surface of the substrate 14.

  The evaporation source 34 of this embodiment allows the film forming material to be continuously attached to all the substrates 14 held by the substrate holder 12 that receives the output from the motor and rotates about the vertical axis. It is installed in such an arrangement and orientation as possible.

An ion source 38 is disposed on the side surface inside the vacuum vessel 10. The ion source 38 (film formation assist means) is a film formation assist device that emits an ion beam toward the substrate 14, and from a reactive gas (for example, O ₂ ) or rare gas (for example, Ar) plasma, Positively charged ions (O ₂ ⁺ , Ar ⁺ ) are extracted, accelerated by an acceleration voltage, and emitted toward the substrate 14. Above the ion source 38, a shutter 38a is provided that can be opened and closed at a position where an ion beam from the ion source 38 toward the substrate 14 is blocked. The shutter 38a is appropriately controlled to open and close by a command from the controller 52.

  The ion source 38 according to the present embodiment partially irradiates a part of all the substrates 14 held by the substrate holder 12 receiving the output from the motor and rotating around the vertical axis. It is arranged in such a configuration (for example, the curvature of the electrode), arrangement and / or orientation that can be performed. Specifically, for example, as shown in FIG. 2, a part of the substrate holder 12 in the middle of rotation, that is, a part of all the substrates 14 is partially irradiated with an ion beam (hereinafter also referred to as “partial irradiation”). The ion source 38 is arranged (region A2 surrounded by a wavy line in FIG. 2).

  That is, the ion source 38 is arranged so that the ion beam irradiation area (A2) is smaller than the film formation material supply area (area A1 surrounded by the two-dot chain line in FIG. 2) by the vapor deposition source 34 (A2). <A1). In the present embodiment, it is particularly preferable that the ion source 38 is arranged so that A2 ≦ ((1/2) · A1). By arranging the ion source 38 in this way, the ion beam irradiated from the ion source 38 is partially irradiated to a part of the substrate 14 held by the rotating substrate holder 12. This effectively improves the quality of the thin film deposited on the surface of the substrate 14. The improvement of the film quality will be described later.

  In addition to the mode of FIG. 2, for example, the ion source 38 may be arranged so that the ion beam can be partially irradiated in the region A2 'surrounded by the dashed line in FIG. However, in the embodiment of FIG. 3, a specific substrate 14 held near the rotation axis of the substrate holder 12 (see “×” in the figure) and another substrate 14 held near the outer periphery of the substrate holder 12 In some cases, the relative irradiation time of the ion beam may be different. In this case, the characteristics of all the substrates 14 held by the substrate holder 12 may not be made uniform. Therefore, in the present embodiment, as shown in FIG. 2, the ion source 38 can be irradiated with an ion beam so as to irradiate a region surrounded by a vertically long closed curve (for example, approximately an ellipse) along the moving direction of the substrate 14. It is desirable to arrange.

  Returning to FIG. 1, in this embodiment, adjustment walls 38b and 38b for adjusting the directivity of ions drawn from the ion source 38 may be provided above the shutter 38a. By providing this, a predetermined region (for example, the region A2 in FIG. 2 or the region A2 ′ in FIG. 3) of the substrate holder 12 can be irradiated regardless of the arrangement of the ion source 38 described above. it can.

  The ion source 38 of the present embodiment is attached to the side surface of the vacuum vessel 10 via an attachment 44 as a support device.

  By attaching the ion source 38 to the side surface side of the vacuum vessel 10, the ion beam irradiated from the ion source 38 is shorter than the case where the ion source 38 is disposed below the inside of the vacuum vessel 10, as in the vapor deposition source 34. It reaches the substrate 14 at a flight distance. As a result, it is possible to suppress a decrease in ion kinetic energy when colliding with the substrate 14. Further, by attaching the ion source 38 to the side surface side of the vacuum vessel 10, the ion beam is incident on the substrate 14 with an angle. By bombarding the surface of the substrate 14 with an ion beam that maintains a high kinetic energy from an oblique direction, a larger amount of energy can be applied to the vapor deposition material deposited on the surface of the substrate 14. The effect of can be obtained.

  The ion source 38 of the present embodiment is disposed at a position closer to the substrate 14 by the length of the main body of the ion source 38 than the position where the vapor deposition source 34 is disposed. In addition, a part of the side surface of the vacuum vessel 10 is inclined so that the ion source 38 can be easily attached, but the position where the ion source 38 is attached is arbitrary. Further, the attachment position of the ion source 38 is not limited to the side surface of the vacuum vessel 10, and may be inside the vacuum vessel 10 similarly to the vapor deposition source 34. In any case, it is attached to a position where a part of the substrate 14 held by the substrate holder 12 can be irradiated with the ion beam.

  The attachment 44 (support means) is a support device for the ion source 38 and is attached to the side surface of the vacuum vessel 10. The attachment 44 fixes a bracket (not shown) fixed to the vacuum vessel 10 side, a pin (not shown) that supports the ion source 38 side so as to be tiltable with respect to the bracket, and the inclination of the ion source 38 at a predetermined position. And a braking member (not shown) made of screws. Therefore, the attachment angle of the ion source 38 can be arbitrarily adjusted. In addition, by arranging a bracket on the vacuum vessel 10 side and fixing it to a base plate (not shown) whose position can be adjusted, not only the mounting angle but also the height and radial positions can be adjusted. ing. The position adjustment in the height direction and the radial direction is performed by moving the base plate in the vertical direction and the radial direction.

  By changing the mounting height h and the radial position of the ion source 38, the ion source 38 and the substrate 14 can be adjusted to an appropriate distance. By changing the mounting angle, the incident ion beam impinging on the substrate 14 can be made. The angle and position can be adjusted. By adjusting the height direction, radial position, and mounting angle of the ion source 38, the loss of the ion beam is minimized, and the irradiation region of the ion source 38 (for example, A2 in FIG. 2 and A2 ′ in FIG. 3) is reduced. In contrast, the ion current density is adjusted to have a uniform distribution.

  The attachment angle θ of the ion source 38 is an angle formed by the axis line that irradiates the ion beam and the rotation axis line of the substrate holder 12. If this angle is too large, an ion beam is incident on the substrate 14 at a low angle. Therefore, even if the ion beam collides with the substrate 14, it is rebounded without exerting a great effect on the substrate 14. It may decrease. On the other hand, even when the mounting angle θ is too small, the ion beam collides with the substrate 14 at an angle close to a right angle, so that a large amount of energy cannot be given to the vapor deposition material, and the deposited vapor deposition layer is densified. The effect may be reduced.

  In the present embodiment, a high ion assist effect can be obtained when the mounting angle θ is in the range of 6 to 70 °, and accordingly, power consumption can be reduced and a thin film with excellent film quality can be obtained. .

  Further, the method of making the ion beam incident on the surface of the substrate 14 from an oblique direction does not depend on the distance between the substrate 14 and the ion source 38. In other words, if the ion beam from the ion source 38 can reach the substrate 14, a high ion assist effect can be obtained by applying a method in which the ion beam is incident on the surface of the substrate 14 from an oblique direction. .

  Of course, the mounting angle θ described above can be appropriately changed depending on the size of the substrate holder 12 and the vacuum container 10 or the film forming material.

  The mounting height h is set so that the distance between the ion source 38 and the substrate 14 is appropriate. If the mounting height h is too high, the mounting angle θ becomes too large. On the other hand, if the mounting height h is too low, the distance between the substrate 14 and the ion source 38 becomes long and the mounting angle θ becomes too small. Therefore, the attachment height h needs to be a position where an appropriate attachment angle θ can be obtained.

  The distance between the ion source 38 and the substrate 14 is preferably equal to or less than the mean free path 1. For example, if the mean free path is 1 = 500 mm, the distance between the ion source 38 and the substrate 14 is preferably 500 mm or less. By making the distance between the ion source 38 and the substrate 14 equal to or less than the mean free path 1, more than half of the ions emitted from the ion source 38 can collide with the substrate 14 in a collision-free state. Since the ion beam can be irradiated onto the substrate 14 with high energy, the effect of ion assist is great, and film formation can be performed with lower power or in a shorter time.

Here, the “distance between the ion source 38 and the substrate 14” refers to the distance between the center of the ion source 38 and the center of the ion source 38 to the center of the substrate holder 12 on the film formation surface side . Similarly, the “distance between the vapor deposition source 34 and the substrate 14” refers to the distance between the center of the vapor deposition source 34 and the center of the vapor deposition source 34 to the center of the substrate holder 12 on the film formation surface side. The “main body length of the ion source 38” is a distance from the electrode of the ion source 38 (ion gun) to the bottom of the ion plasma discharge chamber.

  The attachment position of the ion source 38 is not limited to the position on the side surface side of the vacuum vessel 10 and may be arranged at a position separated from the wall surface on the side surface of the vacuum vessel 10 by the attachment 44. Since the attachment 44 can adjust the position of the ion source 38 also in the radial direction, it can be easily arranged in this manner. In this case, since the ion beam can be irradiated to the substrate 14 from a closer position, a good ion assist effect can be obtained even with lower energy (power consumption). The present embodiment can also be applied to a case where film formation is performed under a film formation condition with a low degree of vacuum using a large vapor deposition apparatus. The tree embodiment can also be suitably applied to a vapor deposition apparatus in which the distance between the substrate holder 12 and the inner wall surface of the vacuum vessel 10 is separated. Of course, the ion source 38 may be installed at the bottom. In this case, a pedestal may be installed at the bottom and the ion source 38 may be attached on the pedestal.

  Further, as described above, since a good ion assist effect can be obtained even with a lower ion current (power consumption), the vapor deposition material adhering to the surface of the substrate 14 or the substrate holder 12 due to the collision of the ion beam. Delamination decreased. That is, foreign substances existing in the vacuum vessel 10 can be reduced, and film formation with higher accuracy can be performed. That is, it is possible to manufacture a highly accurate optical filter while reducing the manufacturing cost by improving the yield of the film forming process.

  Further, by attaching the ion source 38 to the side surface of the vacuum vessel 10, the ion beam is not obstructed by a film thickness correction plate (not shown) disposed between the vapor deposition source 34 and the substrate, so that ion loss is prevented. Decreases, and more efficient film formation becomes possible.

  In addition, since the effect of ion assist gradually improves as the incident angle of the ion beam with respect to the substrate 14 increases, the power consumption can be reduced and the life of the ion gun can be extended by increasing the attachment angle θ. .

A neutralizer 40 is disposed on the side surface inside the vacuum vessel 10. The film forming material moving from the evaporation source 34 toward the substrate 14 adheres to the surface of the substrate 14 with high density and strength due to the collision energy of positive ions (ion beams) irradiated from the ion source 38. At this time, the substrate 14 is positively charged by positive ions contained in the ion beam. In addition, since positive ions (for example, O ₂ ⁺ ) ejected from the ion source 38 accumulate on the substrate 14, a phenomenon that the entire substrate 14 is positively charged (charge-up) occurs. When the charge-up occurs, abnormal discharge occurs between the positively charged substrate 14 and other members, and a thin film (insulating film) formed on the surface of the substrate 14 may be destroyed by an impact caused by the discharge. Further, since the substrate 14 is positively charged, collision energy due to positive ions ejected from the ion source 38 is reduced, so that the denseness and adhesion strength of the thin film may be reduced. In this embodiment, the neutralizer 40 is provided in order to eliminate such inconvenience and to electrically neutralize the positive charges accumulated on the substrate 14.

The neutralizer 40 (second film formation assist means) is a film formation assist apparatus that emits electrons (e ⁻ ) toward the substrate 14 during irradiation of the ion beam from the ion source 38, and is a rare gas such as Ar. The electrons are extracted from the plasma, accelerated by the acceleration voltage, and emitted. The electrons emitted from here neutralize charging by ions attached to the surface of the substrate 14.

  The neutralizer 40 is disposed at a predetermined distance from the ion source 38. Note that an adjustment wall (not shown; see, for example, the adjustment wall 38b) for adjusting the directivity of electrons emitted from the neutralizer 40 may be provided above the neutralizer 40.

  The neutralizer 40 may be disposed at any position where it can be neutralized by irradiating the substrate 14 with electrons. Similar to the ion source 38 described above, the electrons are distributed to all the substrates 14 held by the substrate holder 12. Alternatively, an arrangement capable of irradiating a part of the substrate 14 may be used, or an arrangement capable of irradiating the entire substrate 14 with electrons as in the evaporation source 34 described above may be used.

  The neutralizer 40 should just be arrange | positioned in the position which can irradiate the board | substrate 14 with an electron and can neutralize. In this embodiment, the neutralizer 40 is disposed at a position close to the substrate holder 12. By arranging in this way, electrons can be accurately irradiated toward the region of the substrate holder 12 to which the ions irradiated from the ion source 38 adhere.

Further, when the neutralizer 40 is disposed at a position away from the ion source 38 by a predetermined distance, the neutralizer 40 hardly reacts directly with ions moving from the ion source 38 toward the substrate 14, and the substrate holder 12 can be efficiently used. The charge can be neutralized. Therefore, the substrate holder 12 can be suitably neutralized even if the current value applied to the neutralizer 40 is lower than that of the conventional vapor deposition apparatus. Since sufficient electrons can be supplied to the surface of the substrate 14, for example, a dielectric film such as a high refractive index film or a low refractive index film can be completely oxidized.
In the present embodiment, each of the ion source 38 and the neutralizer 40 is constituted by one, but a plurality of these may be arranged. For example, a plurality of ion sources 38 and neutralizers 40 may be provided along the rotation direction of the rotating substrate holder 12. By adopting such a configuration, the present invention can be more effectively applied to a large film forming apparatus including a large size substrate holder 12.

  According to the film forming apparatus 1 according to the present embodiment, the ion source 38 is arranged in such an arrangement that the ion beam can be partially irradiated. Specifically, the ion source 38 is arranged so that the ion beam irradiation area A2 from the ion source 38 is smaller than the film formation material supply area A1 from the vapor deposition source 34 (A2 <A1). As a result, as in the case where the ion beam irradiation area A2 is the entire surface of the substrate holder 12 (that is, all the substrates 14 are irradiated), similarly to the film forming material supply area A1, the thin film is denser. As a result, a high ion assist effect can be obtained. In particular, by arranging the ion source 38 so that A2 is equal to or less than half of A1 (A2 ≦ ((1/2) · A1)), such an effect can be exhibited more remarkably.

  When the ion beam irradiation area A2 is the entire surface of the substrate holder 12 as in the film formation material supply area A1 of the vapor deposition source 34, for example, when the outer diameter of the substrate holder 12 is increased to increase the area, the substrate holder In order for the ion beam to spread over the entire surface of the ion beam 12, it is necessary to increase the divergence angle of the ion beam extracted from the ion source 38. In order to widen the divergence angle of the ion beam, it is necessary to reduce the curvature of the electrode portion located at the tip of the ion source 38, and there is a certain limit to minimizing the electrode curvature. When there is a demand for downsizing the ion source 38 itself, it becomes more difficult to process the electrode.

  Further, when the ion beam irradiation area A2 is the entire surface of the substrate holder 12 (= film formation material supply area A1), if ion assist is to be performed uniformly on all the substrates 14 held by the substrate holder 12, It is necessary to output a large current from the ion source 38. For this reason, plasma discharge is not stabilized, uniform ion assist cannot be performed, and the life of the electrode portion of the ion source 38 is significantly reduced.

  Further, when the ion beam irradiation area A2 is the entire surface of the substrate holder 12, in order to uniformly assist all the substrates 14 at once, it is required to make the ion current density of the ion beam uniform. For this reason, ion current more than necessary is forced to be released, and part of the ion current that comes off the substrate holder 12 and collides with the inner wall of the vacuum vessel 10 is wasted, and the use efficiency of the ion beam is reduced.

<Film formation method>
Next, an example of a film forming method using the film forming apparatus 1 will be described.

  In this embodiment, a case where an optical filter is formed is exemplified. The optical filter formed in this embodiment is formed by alternately laminating a high refractive index substance and a low refractive index substance, and is composed of one or more kinds of evaporation substances (film forming materials). The present invention can also be applied to the formation of an optical filter. In this case, the number and arrangement of the vapor deposition sources 34 can be appropriately changed.

  In addition, as a specific example of the optical filter produced in the present embodiment, a short wavelength transmission filter (SWPF) and an infrared cut filter are cited, but other than this, a short wavelength transmission filter, a bandpass filter, an ND filter, and the like It can also be applied to thin film devices.

  (1) First, a plurality of substrates 14 are set on the lower surface of the substrate holder 12 with the film formation surfaces facing downward. The substrate 14 (base body) is made of a light-transmitting member such as a resin (for example, polyimide) or quartz on which a dielectric film or an absorption film is attached by deposition. The shape of the substrate 14 is not limited to a disk shape, and may be other shapes such as a lens shape, a cylindrical shape, and an annular shape as long as a thin film can be formed on the surface. The substrate 14 is preferably wet-cleaned before or after setting.

(2) Next, after the substrate holder 12 is set inside the vacuum vessel 10, the inside of the vacuum vessel 10 is evacuated to about 10 ⁻⁴ to 10 ⁻² Pa, for example. When the degree of vacuum is higher than 10 ⁻² Pa, the film quality may be deteriorated.

  (3) Next, the electric heater 53 is energized to generate heat, and the substrate holder 12 is rotated at a low speed. This rotation makes the temperature and film forming conditions of the plurality of substrates 14 uniform.

  When the controller 52 determines that the temperature of the substrate 14 is, for example, room temperature to 120 ° C., preferably 50 to 90 ° C., based on the output of the temperature sensor 54, the controller 52 enters a film forming process. If the substrate temperature is less than room temperature, the density of the thin film formed is low, and there is a tendency that sufficient film durability cannot be obtained. When the substrate temperature exceeds 120 ° C., when a plastic substrate is used as the substrate 14, the substrate 14 may be deteriorated or deformed.

In the present embodiment, the ion gun 38 is set in an idle operation state before entering the film forming process. The evaporation source 34 is also prepared so that the film forming material can be immediately diffused (released) by opening the shutter 34a. Examples of the film forming material include a high refractive index substance (for example, Ta ₂ O ₅ and TiO ₂ ) and a low refractive index substance (for example, SiO ₂ ).

  (4) Next, the controller 52 increases the irradiation power (power) of the ion gun 38 from the idle state to a predetermined irradiation power, opens the shutter 38a, opens the shutter 34a, and ion beam assisted deposition of the film forming material. (IAD: Ion-beam Assisted Deposition method). At this time, the operation of the neutralizer 40 is also started. That is, the film forming surface of the substrate 14 is scattered by a film forming material from the evaporation source 34, the step of irradiating an ion beam of an introduction gas (here, oxygen) drawn from the ion gun 38, and the electron irradiation. The process is performed in parallel (film formation process).

  The ion beam assist conditions are as follows. As the gas species introduced into the ion gun 38, for example, oxygen, argon, or a mixed gas of oxygen and argon is preferable. The amount of the gas species introduced is, for example, 1 to 100 sccm, preferably 5 to 50 sccm. “Sccm” is an abbreviation for “standard cc / m”, and represents one at 0 ° C. and 101.3 kPa (1 atm). The acceleration voltage (V) of ions is, for example, 50 to 1200 V, preferably 100 to 1200 V, and more preferably 200 to 400 V. The ion irradiation ion current (I) is, for example, 50 to 1000 mA, preferably 100 to 1000 mA, and more preferably 300 to 600 mA.

  In the present embodiment, as described above, the ion source 38 is arranged so as to be able to partially irradiate the ion beam (A2 <A1, particularly A2 ≦ ((1/2) · A1)). For this reason, when the vapor deposition source 34 and the ion source 38 are operated for the same time, the ion source is longer than the supply time (T1) of the film forming material to the substrate 14 by the vapor deposition source 34 for each substrate 14. Irradiation time (T2) of the ion beam to the substrate 14 by 38 is inevitably shorter (T2 <T1).

  Thereby, the film quality improvement of the thin film deposited on the surface of the substrate 14 is effectively achieved. Here, the improvement of the film quality means that the thin film deposited on the substrate 14 is cleaned and smoothed or the thin film structure is densified, and molecules constituting the vapor deposition layer deposited on the surface of the substrate 14 (vapor deposition molecules). Such an effect is manifested by moving until it stops at a stable position (stable site) on the substrate 14. The movement of vapor deposition molecules is promoted by being hit by the irradiated ion beam (ion).

  In the present embodiment, since the ion beam is partially irradiated so that T2 <T1, a time during which the ion beam is not irradiated to each substrate 14 is secured. While molecules (vapor deposition molecules) constituting the vapor deposition layer deposited on the surface of the substrate 14 are irradiated with an ion beam, a chemical reaction (oxidation) is promoted by the ion beam. There may be a disadvantage that the surface is migrated (physical excitation) by the kinetic energy received. In the present embodiment, while the ion beam is not irradiated onto the substrate 14, the vapor deposition molecules whose surface has been migrated by the ion beam irradiation are stopped (settled) at a stable position (stable site) on the substrate 14. )be able to. Even if ions are irradiated again on the deposition molecules stationary at the stable site, the stationary deposition molecules do not start moving from the stable site, and as a result, a dense and high-quality thin film can be obtained. That is, the thin film becomes dense and compositional uniformity is improved, and distortion of the thin film structure can be reduced. In this way, since the deposited structure has good uniformity, it is possible to obtain an optical filter in which the refractive index fluctuation is small and the light absorption coefficient is stable below a certain level.

  When all the substrates 14 are continuously irradiated with an ion beam (entire surface irradiation), the vapor deposition molecules deposited on the surface of the substrate 14 are excited again before stopping at a stable site on the substrate 14. End up. This is because the ion beam is continuously irradiated. As a result, it becomes difficult to keep the deposited molecules stationary at the stable site, and this is thought to impede the denseness of the thin film.

  In the present embodiment, in particular, the ion source 38 is arranged so as to satisfy A2 ≦ ((1/2) · A1), so that the ion beam is irradiated so as to satisfy T2 ≦ ((1/2) · T1). It is preferable to do.

  By irradiating the ion beam so that T2 ≦ ((1/2) · T1), the film quality of the thin film deposited on the surface of the substrate 14 can be improved more effectively.

  In addition, as a method of making the ion beam irradiation time (T2) shorter than the deposition material supply time (T1), as described above, for example, the operation of the ion source 38 can be performed in addition to the adjustment of the arrangement of the ion source 38. Can also be performed by ON-OFF control.

  The operating conditions of the neutralizer 40 are as follows. The gas species introduced into the neutralizer 40 is, for example, argon. The amount of the gas species introduced is, for example, 10 to 100 sccm, preferably 30 to 50 sccm. The acceleration voltage of electrons is, for example, 20 to 80V, preferably 30 to 70V. The electron current may be a current that can supply a current higher than the ion current.

  While the deposition source 34 discharges the film forming material, the shutter 38a of the ion source 38 is opened to cause the released ions to collide with the substrate 14, thereby smoothing the surface of the film forming material attached to the substrate 14. Densify. By repeating this operation a predetermined number of times, a multilayer film can be formed. Irradiation of the ion beam causes a charge bias on the substrate 14. This charge bias is neutralized by irradiating electrons from the neutralizer 40 toward the substrate 14. In this manner, a thin film is formed on the film formation surface of the substrate 14 with a predetermined thickness.

  (5) The controller 52 continues to monitor the film thickness of the thin film formed on the substrate 14 with the crystal monitor 50, and stops the film formation when a predetermined film thickness is reached. The controller 52 closes the shutter 34a and the shutter 38a when stopping the film formation.

  In the film forming apparatus 1 used for the film forming method according to the present embodiment, the ion source 38 is arranged in such an arrangement that the ion beam can be partially irradiated. Specifically, the ion source 38 is arranged such that the ion beam irradiation area A2 is smaller than the film formation material supply area A1 of the vapor deposition source 34 (A2 <A1). For this reason, according to the film forming method using the film forming apparatus 1 having such a configuration, when the vapor deposition source 34 and the ion source 38 are operated for the same time, the substrate by the vapor deposition source 34 with respect to the substrate 14 per sheet. The irradiation time (T2) of the ion beam to the substrate 14 by the ion source 38 can be made shorter than the supply time (T1) of the film forming material to 14 (T2 ≦ ((1/2) · T1)). .

  As a result, compared with the case where the ion beam irradiation time T2 from the ion source 38 is set to be the same as the film formation material supply time T1 from the vapor deposition source 34, the densification of the thin film is promoted, resulting in high ion assist. An effect can be obtained. In particular, by irradiating the ion beam from the ion source 38 such that T2 is equal to or less than half of T1 (T2 ≦ ((1/2) · T1)), such an effect can be exhibited more remarkably.

  Next, the present invention will be described in more detail with reference to examples that further embody the above-described embodiments.

<< Experiment 1 >>
In this example, the film forming apparatus 1 shown in FIG. 1 configured to perform ion beam assisted deposition was prepared, and an optical filter sample was manufactured under the following conditions. The optical filter sample is a multilayer film of a short wavelength transmission filter (Short Wave Pass Filter: SWPF) composed of 27 layers of a high refractive index film and a low refractive index film.

  The film forming conditions were as follows.

  -Substrate: BK7 (refractive index n = 1.52).

Film forming condition film material (film forming material): Ta ₂ O ₅ (high refractive index film) and SiO ₂ (low refractive index film).
Deposition rate of Ta ₂ O ₅ : 0.5 nm / second, deposition time (T1): 2260 seconds.
SiO ₂ film formation rate: 1.0 nm / second, film formation time (T1): 1500 seconds.

Condition of ion source introduction gas species and introduction amount: O ₂ of 50 sccm.
Ion acceleration voltage: 300V.
Irradiation ion current: 500 mA.
Ion beam irradiation time (T2) during Ta ₂ O ₅ film formation: 1000 seconds.
Ion beam irradiation time (T2) during SiO ₂ film formation: 700 seconds.

Neutralizer condition introduction gas type and introduction amount: Ar 10 sccm,
Electron current: 1A.

  Next, the transmission spectral characteristic (transmittance T) and the reflection spectral characteristic (reflectance R) of the produced optical filter sample were measured, and the sum (R + T) was graphed. The results are shown in FIG. FIG. 4 also shows the characteristics of BK7 as a substrate for reference. Moreover, the average value of the (R + T) value in the wavelength range of 450 to 550 nm in FIG. 4 was plotted. The results are shown in FIG.

  FIG. 6 shows a state in which the ion beam irradiation region (A2) of this example is shown in a positional relationship with respect to the substrate holder 12. FIG.

<< Experiment 2 >>
Prepare a conventional vapor deposition device (not shown) with the same film formation material supply area by the vapor deposition source and ion beam irradiation area by the ion source, and produce an optical filter sample under the following conditions. The transmittance T and reflectance R of the filter sample were measured, and the sum was graphed. The results are shown in FIG. Moreover, the result of having plotted the average value of the (R + T) value in wavelength range 450-550 nm is shown in FIG.

  FIG. 7 shows a state in which the ion beam irradiation area (A1) of this example is shown in a positional relationship with respect to the substrate holder 12.

  The film forming conditions were as follows.

  -Substrate: Same as Experimental Example 1.

Film forming conditions Film material (film forming material) and film forming speeds of Ta ₂ O ₅ and SiO ₂ : both the same as in Experimental Example 1.
Ta ₂ O ₅ deposition time (T1): 2260 seconds.
SiO ₂ deposition time (T1): 1500 seconds.

Condition of ion source introduction gas type, introduction amount, ion acceleration voltage, and ion current: all the same as in Experimental Example 1.
Ion beam irradiation time (T2) during Ta ₂ O ₅ film formation: the same as T1.
Ion beam irradiation time (T2) during SiO ₂ film formation: the same as T1.

  Neutralizer conditions: All are the same as in Experimental Example 1.

<Discussion>
As shown in FIGS. 4 and 5, the sample of Experimental Example 2 shows a large amount of light absorption, whereas the sample of Experimental Example 1 shows no absorption in the entire visible light region. In particular, the (R + T) value in the wavelength region of 450 nm to 550 nm is about 95% for the sample of Experimental Example 2, whereas it is 99.5% or more for the sample of Experimental Example 1, which is a thin film (multilayer film). It was confirmed that the thin film had good optical properties.

  In Experimental Example 1, a thin film having good optical characteristics could be formed for the following reason. That is, in the film forming apparatus 1 of Experimental Example 1, the ion source 38 is arranged so that the ion beam irradiation area (A2) is smaller than the film forming material supply area (A1) by the vapor deposition source 34 (A2 <A1). Thereby, the irradiation time (T2) of the ion beam by the ion source 38 is made shorter than the supply time (T1) of the film forming material by the evaporation source 34. For this reason, the time when the ion beam is not irradiated to each substrate 14 is secured. While the ion beam is not irradiated, the vapor deposition molecules deposited on the surface of the substrate 14 can be moved to a stable position on the substrate 14 until it stops, and as a result, densification of the thin film is promoted. It is considered a thing. Thereby, the thin film became dense and a high ion assist effect could be obtained.

<< Experimental Example 3 >>
The ion beam irradiation time (T2) during the Ta ₂ O ₅ film formation is 800 seconds, and the ion beam irradiation time (T2) during the SiO ₂ film formation is 700 seconds, except that T2 is further shortened compared to Experimental Example 1. Produced an optical filter sample under the same conditions as in Experimental Example 1 and evaluated in the same manner.

  As a result, as shown in FIGS. 4 and 5, it was confirmed that a thin film in which light absorption was not confirmed in the entire visible light region could be formed. In particular, for the (R + T) value in the wavelength region of 450 nm to 550 nm, a value of almost 100%, which is higher than the result of Experimental Example 1, was obtained, and it was confirmed that a thin film having very good optical characteristics could be formed. It was.

FIG. 1 is a sectional view of a film forming apparatus according to an embodiment of the present invention as seen from the front. FIG. 2 is a sectional view taken along line II-II in FIG. FIG. 3 is a cross-sectional view showing another embodiment corresponding to FIG. FIG. 4 is a graph showing the transmittance + reflectance of the optical filters of Experimental Example 1 and Experimental Example 2. FIG. 5 is a graph showing an average value of (R + T) values in the wavelength region of 450 to 550 nm in FIG. FIG. 6 is a schematic diagram showing an ion beam irradiation region in a positional relationship with respect to the substrate holder in Experimental Example 1 (Example). FIG. 7 is a schematic diagram showing an ion beam irradiation region in a positional relationship with respect to the substrate holder in Experimental Example 2 (Comparative Example).

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Film-forming apparatus, 10 ... Vacuum container, 12 ... Substrate holder (base | substrate holding means), 14 ... Substrate (base | substrate), 34 ... Deposition source (film-forming means), 34a, 38a ... Shutter, 34b ... Crucible, 34c ... Electron gun, 34d ... Electron gun power supply, 38 ... Ion source (film formation assist means), 38b ... Adjustment wall, 44 ... Attachment (support means), 40 ... Neutralizer (second film formation assist means), 50 ... Crystal Monitor, 51 ... Film thickness detection unit, 52 ... Controller, 53 ... Electric heater, 54 ... Temperature sensor.

Claims (9)

With continuously supplying the film-forming material for all of the substrate which is rotating is held in the substrate holding surface by supplying a film forming material toward the entire area of the substrate holding surface of the substrate holding means, said substrate while providing an assist effect by irradiating continuously said ion to a part of the substrate by irradiating the ion toward the partial area of the holding surface, depositing a thin film on the surface of the substrate A characteristic film forming method. In the film-forming method of Claim 1 , When the supply time of the said film-forming material with respect to the base | substrate per sheet | seat is set to T1, and the irradiation time of the said ion is set to T2, T2 <= ((1/2) * T1) The film formation method is characterized by irradiating the ions so that 2. The film forming method according to claim 1 , wherein A1 is a supply region of the film forming material to the substrate holding unit and A2 is an irradiation region of the ions to the substrate holding unit, and A2 ≦ ((1/2). A film forming method of irradiating the ions so as to satisfy A1). 4. The film forming method according to claim 1 , wherein the ion irradiation region is a region surrounded by a vertically long closed curve along the moving direction of the substrate. In any one film forming method according to claim 1-4, film formation method accelerating voltage is characterized by using the ion 50～1200V. In any film forming method according to one of claims 1 to 5, the film forming method of irradiating ion current is characterized by using the ion 50～1000MA. In any film forming method according to one of claims 1 to 6, the film forming method characterized by using an ion containing at least oxygen. A substrate holding means disposed rotatably in the vacuum vessel and holding the substrate;
A deposition means for film forming material to the entire area of the substrate holding surface is arranged and oriented so as to be supplied installed in the vacuum chamber of the substrate holding means,
Partially irradiated can become such a configuration to part of the area of the substrate holding surface ions, placement and / or orientation in the film formation assisting means which is Installation into the vacuum container, a film deposition apparatus . 9. The film forming apparatus according to claim 8 , wherein the film forming assist means is disposed in the vacuum container so as to irradiate ions to not more than half of the entire area of the substrate holding surface . A film forming apparatus characterized by the above.

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