JP2006302652A - Plasma treatment device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma treatment device which improves precision of a plasma treatment of an object and which is stand-alone. <P>SOLUTION: The plasma treatment device has a plasma irradiating unit which irradiates plasma on the surface of an object, a posture control unit 30 controlling a plasma irradiating posture of the plasma irradiating unit, position control units 10, 11, 51 controlling a plasma irradiating position on the surface of the object, a radical measuring unit 41 measuring a radical density irradiated by the plasma irradiating unit, and a first control unit 52 which, in accordance with the radical density measured by the radical measurement unit, controls a plasma generating volume of the plasma irradiating unit. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an apparatus for performing plasma processing such as processing, cleaning, film formation, or modification of a surface of a substance using ions or radicals generated from an atmospheric pressure plasma source.

  Conventionally, it is known to perform plasma processing such as processing, cleaning, film formation, or modification of the surface of a substance using plasma. As apparatuses for modifying the surface of an object, the following Patent Documents 1 and 2 are known. This device generates plasma between electrodes, puts the plasma on a gas flow, outputs the plasma to the outside, and irradiates the surface of the object. As a method for modifying the surface of an ophthalmic lens, a method described in Patent Document 3 below is known. In this apparatus, a gas is introduced between the electrodes, and a voltage of 20 to 30 kHz is applied between the electrodes at 10 to 20 kV to generate plasma.

Japanese Patent Publication No. 1-44273 JP-A-5-23578 Japanese Patent No. 349497

  However, these devices simply irradiate an object with the generated plasma, and perform feedback control to obtain an optimal plasma state or detect the plasma processing state to control the plasma irradiation time. No such thing has been done. For this reason, there has been a problem that the accuracy of the plasma treatment for the object is not improved.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to configure an autonomous plasma processing apparatus with improved accuracy of plasma processing of an object.

In order to solve the above problems, the following means are effective.
That is, the first means of the present invention is a plasma processing apparatus that processes an object with plasma, a plasma irradiation apparatus that irradiates plasma on the surface of the object, an attitude control apparatus that controls a plasma irradiation attitude of the plasma irradiation apparatus, A position control device for controlling the irradiation position of plasma on the surface of the object, a radical measurement device for measuring the radical density irradiated by the plasma irradiation device, and a plasma irradiation device according to the radical density measured by the radical measurement device A plasma processing apparatus having a first control device for controlling a plasma generation amount.
In other words, the radical density is measured, and the plasma irradiation direction and position are controlled while controlling the plasma generation amount according to the density.

Further, the second means of the present invention is a plasma processing apparatus for processing an object with plasma, a plasma irradiation apparatus for irradiating plasma on the surface of the object, an attitude control apparatus for controlling a plasma irradiation attitude of the plasma irradiation apparatus, According to the position control device that controls the irradiation position of the plasma on the object surface, the environmental state measurement device that measures the environmental state consisting of the surface state of the object or the concentration of the reaction product, and the measurement value by the environmental state measurement device, It has a 2nd control apparatus which controls the irradiation time by a plasma irradiation apparatus, It is a plasma processing apparatus characterized by the above-mentioned.
The feature is that the surface state of the object or the concentration of the reaction product is measured, and the plasma irradiation position and the irradiation direction are sequentially controlled while controlling the plasma irradiation time from these values.

Further, the third means of the present invention includes an environmental state measuring device for measuring an environmental state consisting of the surface state of the object or the concentration of the reaction product, and irradiation by the plasma irradiation device according to the measurement value by the environmental state measuring device. The plasma processing apparatus according to claim 1, further comprising a second control device that controls time.
This apparatus is a combination of the first means and the second means, measures the surface state of the object or the concentration of the reaction product, controls the plasma irradiation time from these values, and radicals It is characterized in that the plasma irradiation position and irradiation direction are sequentially controlled while measuring the density and controlling the plasma generation amount so that the value becomes a predetermined value.

  The fourth means of the present invention has an imaging device for imaging an object, determines a region to be irradiated with plasma from an image captured by the imaging device, controls the attitude control device and the position and orientation device, The plasma processing apparatus according to any one of claims 1 to 3, further comprising a third control device that irradiates the region with plasma. A feature is that a region to be irradiated with plasma is determined by an imaging apparatus, and the region is sequentially irradiated with plasma. For example, it is characterized in that a dirty spot is measured with an imaging device and a region to be irradiated with plasma is determined, or a region is irradiated with plasma by specifying the shape of an object.

  According to the first means, the radical density is measured, and the plasma irradiation direction and position are controlled while controlling the plasma generation amount according to the density. Therefore, since the radical density at the plasma irradiation point on the object can be stably controlled to a desired value, the processing accuracy by plasma is improved. In addition, since the radical density at the plasma irradiation position on the object can be controlled to a desired value while sequentially controlling the plasma irradiation position and irradiation direction on the object, the radical density according to the processing location can be controlled.

  According to the second means, the surface state of the object or the concentration of the reaction product is measured, and the plasma irradiation position and the irradiation direction are sequentially controlled while controlling the plasma irradiation time from these values. . For this reason, it is possible to control the plasma processing time for the object according to the purpose. For example, if the roughness of the surface of the object is below a predetermined value, plasma irradiation is stopped, or the concentration of gas volatilized by reaction of dirt on the object surface with radicals is measured. When the plasma irradiation is stopped when the predetermined value or less is reached, cleaning of the surface of the object can be completed. Thereby, the plasma processing time for the entire object can be shortened, and the processing accuracy can be improved.

  According to the third means, the surface state of the object or the concentration of the reaction product is measured, the plasma irradiation time is controlled from these values, the radical density is measured, and the plasma is set so that the value becomes a predetermined value. The amount generated is controlled. Therefore, it is possible to stably irradiate an object with plasma with a radical density suitable for the purpose, and at the end of processing, the processing time does not become longer than necessary. Therefore, high-precision plasma processing can be performed in a short time.

  According to the fourth means, an image of an object is picked up by an imaging device, a region to be irradiated with plasma is determined, and the region is sequentially irradiated with plasma. Accordingly, removal of dirt and other plasma treatment can be automatically performed over the entire object, and workability is improved.

Hereinafter, the present invention will be described based on specific examples.
However, the embodiments of the present invention are not limited to the following examples.

First, the configuration of the plasma irradiation apparatus will be described.
The configuration of the first type of plasma irradiation apparatus is as follows.
A plasma irradiation apparatus includes a hollow cylindrical metal outer conductor forming an outer shell portion of a cavity, and a cylindrical insulator coaxial with the outer conductor, at least partially disposed inside the outer conductor. And a cylindrical metal plasma material gas introduction pipe coaxial with the outer conductor, a part of which is disposed inside the insulator and electrically connected to the outer conductor, and the insulator and the inner conductor. A coaxial coupling antenna having a loop coaxial with the outer conductor, which radiates microwaves to the cavity, and disposed inside the insulator and in front of the gas outlet of the plasma material gas introduction pipe And a discharge antenna made of metal, whereby atmospheric pressure plasma is emitted from the front opening end of the insulator to the object.

According to this apparatus, a high electric field is generated in the cavity by the microwave, and the electric field is concentrated on the discharge antenna. Therefore, the plasma material gas introduced from the plasma material gas introduction tube is efficiently in a plasma state. . At this time, since the inside of the plasma material gas introduction pipe and the above-described insulator pipe is substantially atmospheric pressure, by optimizing the injection flow rate of the plasma material gas, a plasma gas with good purity is introduced in front of the apparatus. Can be released. Since the coaxially coupled antenna is used, microwaves can be supplied to the coaxially coupled antenna using a coaxial cable without using a waveguide, so that the apparatus can be made compact. With this configuration, the object can be efficiently irradiated with plasma, ions, and radicals, and the surface of the object can be plasma treated.
However, as the insulator, for example, quartz, quartz glass, ceramics, or the like can be used.
Hereinafter, in the present specification, the side from which the atmospheric pressure plasma is emitted is the front of the plasma irradiation apparatus. Therefore, the introduction port into which the plasma material gas is introduced in the plasma material gas introduction pipe is located behind the plasma irradiation apparatus.

Moreover, it is desirable to form the front part of said outer conductor from the substantially truncated-conical side wall part which has the through-hole which penetrates said insulator on an axis | shaft. With this configuration, the electric field is concentrated well in the vicinity of the through hole, so that the electric field is more efficiently concentrated on the discharge antenna. For this reason, the electric power consumed for plasma generation can be suppressed.
In addition, it is desirable to arrange the loop of the coaxially coupled antenna on a bisector of the overall axial length of the cavity. However, this trisection point is the internal division point of the full length. Although there are two internal dividing points, the above-described coaxially-coupled antenna loop may be disposed on either one, or the above-described coaxially-coupled antennas may be disposed on both bisectors. However, when the above coaxially coupled antennas are arranged on both halves, a delay circuit is required because the phases of both microwaves must be shifted by π / 2. Therefore, it is desirable to provide the above coaxially coupled antenna in one place in terms of simplification of structure, size reduction, and weight reduction. With this configuration, it is possible to efficiently supply microwaves to the discharge antenna while ensuring a short overall length of the axial device. Therefore, both downsizing and power saving of the device can be rationally achieved.

Further, it is desirable to provide a protrusion protruding in the direction in which atmospheric pressure plasma is emitted on the discharge antenna, and to dispose this protrusion on the axis of the insulator. With this configuration, the direction in which the plasma is generated coincides with the direction in which the plasma should be emitted, so that the generated plasma can be immediately released while eliminating waste such as extinction and attenuation of the plasma as much as possible.
The discharge antenna is preferably a spiral filament. With this configuration, since the discharge antenna is a spiral filament, it is possible to easily generate plasma by concentrating microwaves on this portion.

  The discharge antenna is preferably made of tungsten mixed with thorium. Since the discharge antenna is made of tungsten mixed with thorium, electrons are easily emitted by heating with microwaves, so that plasma can be easily generated in this portion.

  In addition, it is desirable to supply power to the above-described coaxially coupled antenna through a coaxial cable. The coaxial cable is flexible and can be bundled in a small size, and is easy to handle. Therefore, according to this configuration, it is possible to input microwaves to the device through a coaxial cable, and it is easy to handle and a device that is much more compact than the case of introducing microwaves through a waveguide or the like. Can be configured. A microwave can be easily supplied to the cavity by the coaxially coupled antenna. Further, if an N-type coaxial connector or the like is used, it is easy to attach and detach, and furthermore, these parts are standardized or commercially available, so that the design and manufacture of the apparatus are simplified.

  Furthermore, it is desirable to provide a variable mechanism capable of adjusting the axial position of the plasma material gas introduction pipe. By adjusting the position of the plasma material gas introduction tube in the axial direction, the reflectance of the microwave with respect to the cavity of the coaxially coupled antenna can be minimized. Usually, the optimum conditions for impedance matching between the cavity and the coaxially coupled antenna differ depending on whether plasma is generated or not. However, since the impedance matching can be easily optimized by using the variable mechanism as needed, it is possible to always realize a plasma irradiation apparatus with high power use efficiency.

The configuration of the second type of plasma irradiation apparatus is as follows.
This plasma irradiation apparatus has two electrodes that are used across a gap so as to form an opening of a desired shape, and at least one recess is formed in a portion facing the gap between at least one of the electrodes. By injecting a gas that generates plasma into the gap from the opposite side of the opening, plasma can be generated by hollow cathode discharge in the recess, and plasma can be emitted from the opening to the object It is the apparatus characterized by this.

The configuration of the third type of plasma irradiation apparatus is as follows.
This plasma processing apparatus has two electrodes that are used with a gap therebetween so as to form an opening having a desired shape, and corresponds to the shape of the opening at least in a portion facing the gap between the electrodes. A series of grooves are formed, and by injecting a gas that generates plasma into the gap from the opposite side of the opening, it is possible to generate plasma by hollow cathode discharge in the groove, and plasma is generated in the range of the shape of the opening. The device is characterized in that it can be released to an object.

  With the configuration of the second and third plasma irradiation apparatuses described above, it is easy to irradiate plasma to a minute or specially shaped region particularly efficiently by setting the gap between the two electrodes to a desired shape. Can be achieved. In this case, a concave portion or a series of groove portions may be formed on the cathode side when a DC power source is used, on at least one, and preferably both on the AC power source. With this configuration, the object can be efficiently irradiated with plasma, ions, and radicals, and the surface of the object can be subjected to plasma treatment.

In order to perform hydrophilic treatment on the object, it is desirable that the gas for generating plasma is at least one of nitrogen, oxygen, helium, neon, argon, and air. Further, for processing, it is desirable to use a plasma of a gas containing fluorine or chlorine. For example, fluorocarbon (C _x F _y), to use a gas hydrofluorination carbon (C _x H _y F _z) is desirable.

  Plasma treatment of the object is optional. For example, a hydrophilic treatment is performed on the object, a water repellency treatment is performed, the surface is processed smoothly, a coating treatment such as a nitride film or a silicon film is performed on the surface, and the surface is cleaned. Examples of the object to be subjected to the hydrophilic treatment include an ophthalmic lens, a contact lens, a spectacle lens, and an optical lens. Ophthalmic lenses and contact lenses include silicon-containing hydrous soft contact lenses, silicon-containing non-hydrous soft contact lenses, silicon-containing gas-permeable hard contact lenses, and intraocular lenses composed of polymers based on ethyl methacrylate. Can be mentioned.

  For processing and cleaning the surface of an object, the surface is chemically vaporized by plasma CVM (Chemical Vaporization Machining) method using fluorine radicals to convert it into volatile fluoride and evaporate it. There are processing methods and cleaning methods.

  The first type of plasma irradiation apparatus generates plasma in the vicinity of the front opening end of the insulator and irradiates the plasma to a non-processed object disposed in the vicinity of the opening of the opening end. The generation area is not necessary. What is necessary is just to form the shape of an opening part according to a non-processed object. The opening is preferably formed in a linear or curved slit in accordance with the surface shape of the object. Of course, it may be circular. Stainless steel, molybdenum, tantalum, nickel, copper, tungsten, or alloys thereof can be used for the discharge antenna and the plasma gas introduction tube. The length of the front opening end of the insulator is preferably about 20 to 50 mm in the gas flow path direction. When the opening is linear, the shape can be smoothly changed from a circular shape to a linear shape. As a gas for generating plasma, air, oxygen, for example, He, Ne, Ar or other rare gas, nitrogen, hydrogen, or the like can be used at atmospheric pressure. The gas flow rate, supply amount, or degree of vacuum can be set arbitrarily.

  The distance between the front opening end of the insulator and the object is also related to the gas flow velocity, but is preferably in the range of 2 mm to 20 mm. More desirably, it is 3 mm to 12 mm, and most desirably 4 mm to 8 mm. In short, if hydrophilic treatment is performed on the surface of an object, the density of fluorine radicals is the highest if the surface is CVM processed at a distance where the density of hydrophilic radicals is highest and the electron density is lowest. It is preferable to set a distance that is high and has the lowest electron density. Thereby, charge-up damage to the substrate can be prevented, and the most efficient hydrophilic treatment and grinding can be performed.

  For preventing oxidation of the electrode, nitrogen, Ar, or a gas containing hydrogen having a reducing action may be used. In addition, by generating a plurality of types of plasma, it is possible to react only with constituent atoms on the surface of the object and not with other atoms. It is desirable to suck the gas after the reaction from the irradiated part of the plasma to the object. This prevents molecules that have reacted with the object from adhering to other regions. Furthermore, the temperature and density of the plasma are measured using laser light absorption spectroscopy, etc., and the applied voltage magnitude, pulse application, duty ratio, irradiation time, gas, etc. so that the predetermined temperature and density are obtained. It is desirable to feedback control the flow rate. As a result, high-quality hydrophilic processing and shortening of the grinding process can be realized.

  In addition, assuming that the shape of the opening at the front opening end of the insulator is linear, the width and length of the opening are set appropriately to irradiate the entire object or a desired region with plasma. Is possible. Furthermore, it is desirable to cool the gas and supply it to the apparatus to turn it into plasma. As a result, the temperature of the plasma is prevented from rising, and the influence on the object to be processed, for example, damage to the soft contact lens can be prevented. Since this plasma irradiation device is composed of a cylindrical body part through which gas passes and an opening end provided at the tip thereof, it can be very small, and the gas supply direction and the plasma blowing direction, The shape of the blowout plasma can be arbitrarily designed. Therefore, it is possible to provide a plurality of openings through which these plasmas are blown and supply gas from any direction. Therefore, it is possible to irradiate plasma only at a desired portion of the object with high density, and it is possible to effectively attach the present reformer even in a narrow space. The pressure is preferably atmospheric pressure, and it is desirable to form atmospheric pressure plasma.

  In addition to the above, the following can be said as another type of plasma irradiation apparatus. In order to form the opening, a jig composed of two electrodes and an insulator for fixing the electrodes is required. The simplest configuration is to provide a gas channel in the insulator and to provide two electrodes at the end of the gas channel. For example, in order to form a rectangular (stripe-shaped) opening, it is preferable to form four sides (surfaces) using a surface of two electrodes facing each other and a jig made of an insulator. A jig made of an insulator having a gas flow path may be constituted by one piece or a combination of a plurality of parts.

  As the material of the electrode, stainless steel, molybdenum, tantalum, nickel, copper, tungsten, or an alloy thereof can be used. It is desirable that the surface on which the concave portion for causing hollow cathode discharge is formed has a thickness of about 1 to 30 mm in the gas flow path direction. By increasing the thickness, the recesses can be formed in multiple stages, the gas flow rate can be improved, and the plasma generation density can be improved. For example, the recesses that cause the hollow cathode discharge may have a width and a depth of about 1 mm or less and about 0.5 mm. The concave portions may be formed discontinuously in a dot shape or may be formed continuously in a groove shape, but it is desirable that the concave portions be continuous. The shape of the concave portion can be arbitrarily formed as a cylindrical surface, a hemispherical surface, a prismatic surface, a pyramid, or the like.

  The type of gas is as described above. The gas flow rate, supply amount, or degree of vacuum can be set arbitrarily. Further, the present invention does not generate plasma by high frequency, and the power source connected to the electrode is direct current, alternating current, or any other, and the frequency is not limited.

  The distance between the opening and the object to be processed is also related to the gas flow velocity, but is preferably in the range of 2 mm to 20 mm. More desirably, it is 3 mm to 12 mm, and most desirably 4 mm to 8 mm. In short, it is preferable to set the distance such that the density of oxygen radicals is highest and the electron density is lowest on the surface of the object. Thereby, charge-up damage to the object can be prevented, and the most efficient cleaning is possible.

  Since this plasma irradiation apparatus is composed of a cylindrical body portion through which gas passes and an opening for forming a counter electrode provided at the tip thereof, it can be very small, and the gas supply direction and plasma It is possible to freely design the blowing direction, the shape of the blowing plasma, and the like. Therefore, it is possible to provide a plurality of openings through which these plasmas are blown, and to supply gas from any direction. Therefore, it is possible to irradiate plasma only at a desired region of the object with high density, and it is possible to effectively attach the present reformer even in a narrow space.

  Other features are the same as those described in the plasma irradiation apparatus.

  The attitude control device is a device that is equipped with the plasma irradiation device and controls the irradiation direction of the plasma on the object. The posture can be controlled by using a mechanism similar to the wrist portion of the robot. The position control device that determines the position of the irradiation point is a device that controls the xyz coordinates of the irradiation point. A table on which an object is placed is controlled in the xyz direction, a table on which an object is placed is controlled in the xy direction on a horizontal plane, and the plasma irradiation apparatus is moved in the z direction. Various known methods such as a method of controlling the irradiation position by holding the irradiation device can be employed.

  As a radical measuring apparatus, there is known an apparatus that irradiates a radical with laser light and measures the radical density and type based on the absorption rate. Further, the type and density of radicals may be measured by spectroscopic analysis. In order to control the amount of plasma generated in accordance with the radical density, the flow rate of gas, the power applied to generate plasma, the type of gas, and the like can be controlled.

  As an environmental condition measuring device that detects the surface state of an object, an apparatus that measures the surface roughness by irradiating the object with light and measuring the reflectance or measuring the ratio of irregular reflection is used. it can. The concentration of the reaction product generated as a result of the reaction between the object and the radical is determined from the absorption rate obtained by irradiating the reaction product with a laser. A device capable of measuring the density and the density can be used as an environmental state measuring device.

Hereinafter, the present invention will be described based on specific examples.
However, the embodiments of the present invention are not limited to the following examples.

The present embodiment is an example of a plasma processing apparatus that corrects the surface accuracy (roughness) of the surface of a mold and planarizes the surface using plasma of a gas containing fluorine.
In FIG. 1, a mold 20 that is an object to be processed is disposed on an xy table driving mechanism 10 that can move in the x-axis and y-axis directions. In the z-axis direction, a z-axis drive mechanism 11 that is movable in the z-axis direction is provided. The xy table drive mechanism 10 and the z-axis drive mechanism 11 constitute a position control device. The z-axis drive mechanism 11 is provided with a wrist mechanism 12 composed of a rotation mechanism in which three rotation axes are orthogonal to each other, and a plasma irradiation device 30 is attached to a flange 13 of the wrist mechanism 12. The wrist mechanism 12 and the flange 13 constitute an attitude control device.

  The flange 13 is provided with a radical sensor 41 that measures the density of radicals irradiated from the plasma irradiation device 30. The radical sensor 41 is a device that irradiates a radical with a laser and measures the lasil density from the absorption rate of the laser (for example, Japanese Patent Laid-Open No. 2000-123996). Further, the flange 13 is provided with a surface sensor 42 for measuring the surface roughness at the plasma irradiation point of the mold 20. The surface sensor 42 is a device that measures surface roughness by irradiating a mold with a laser and measuring scattered light. In addition, the surface roughness may be measured from the laser interference pattern.

  The xy table driving mechanism 10, the z-axis driving mechanism 11, and the wrist mechanism 12 are controlled by a stage controller 51. The stage controller 51 controls the xyz coordinates of the plasma irradiation point and controls the attitude angles θ1, θ2, and θ3 of the plasma irradiation device 30. Outputs of the radical sensor 41 and the surface sensor 42 are input to the control device 50. The control device 50 inputs the output signal of the radical sensor 41 and controls the plasma control device 52 so that the measured value becomes a predetermined value. The plasma control device 52 controls the supply power to the plasma irradiation device 30, the duty ratio if it is pulsed power, if it is a plurality of gases, the supply ratio of these gases, the flow rate of the gas, It is a device that controls the plasma state such as the type of particles.

  The control device 50 is a device for controlling the entire plasma processing apparatus, stores the position and orientation of the teaching point on the machining path of the die 30 taught in advance, and interpolates the position between the teaching points. It is a device that controls and controls the plasma irradiation point (xyz coordinates) and the irradiation direction (the orientations of θ1, θ2, and θ3). This calculation is a process performed by a normal robot or a three-dimensional machine tool. The first control device includes a control device 50 and a plasma control device 52, and the second control device and the third control device include the control device 50. A part of the position control device and the posture control device includes a stage controller 51 and a control device 50.

  Next, the operation of the entire apparatus will be described. By outputting a command signal from the control device 50 to the stage controller 51, the plasma irradiation point (xyz coordinates) and the irradiation direction (the orientations of θ1, θ2, and θ3) are sequentially controlled. Further, a control signal is output from the control device 50 to the plasma control device 52, and an output signal of the radical sensor 41 is input, and feedback control is always performed so that the radical density at the plasma irradiation point becomes a predetermined value. Further, as processing proceeds, an output signal from the surface sensor 42 is input to the control device 50, and the surface roughness of the plasma irradiation point is measured. The moving speed of the plasma irradiation point is determined so that the surface roughness is smaller than a value determined in advance by the position of the mold 20. Based on this moving speed, the stage controller 51 is controlled, and the processing by the CVM is continuously executed at such a speed that the surface accuracy of the mold 20 satisfies a predetermined requirement.

  In this way, while scanning the irradiation point of the plasma on the mold 20, the radical irradiation density is made constant, uniform, or changed depending on the region of the mold 20, and the radical density is set to a desired value. It is possible to perform mirror finishing so that the roughness of the surface of the mold 20 becomes a certain value or less. This apparatus is an apparatus that can autonomously perform three-dimensional processing while appropriately controlling the irradiation density and irradiation time of radicals per unit area on the mold 20.

Next, an example will be described in which the present plasma processing apparatus is an apparatus for removing mold stains remaining during molding.
The difference from the apparatus of the first embodiment is that a CCD camera 43 that captures the entire image of the mold 20 and a CCD camera 44 that is attached to the flange 13 and captures a processing area of the mold 20 are provided. Instead of this, a gas sensor 45 for detecting the gas of the reaction product is provided. The gas sensor 45 is a device that measures the amount of gas generated from the absorption rate by irradiating a laser. Alternatively, a sensor that measures the amount of gas by emission spectroscopy of the gas can be used.

Control of the radical density at the plasma irradiation point is the same as in the first embodiment. The whole image of the mold 20 is picked up by the CCD camera 43, and a dirty region is specified by image analysis of this image. And the position and attitude | position of the plasma irradiation apparatus 30 are sequentially controlled by the specified dirty area | region. In the dirty area, the CCD camera 44 captures a detailed image of the area, scans the position of the plasma irradiation device 30 in that area, and changes the posture. By this operation, the contamination in the region is removed by fluorine radicals obtained from the gas plasma containing fluorine. At this time, the gas sensor 45 detects gas molecules made of a compound of dirt atoms and fluorine. Then, when the measurement result by the gas sensor 45 becomes lower than a predetermined concentration value, the cleaning of the area is finished. Then, the control device 50 moves the plasma irradiation device 30 to the next dirty region, and a similar cleaning process is executed. If the dirt can be determined from the outer shape, the CCD camera 44 may be used instead of the gas sensor 45 to determine whether or not the dirt has been removed from the captured image.
Furthermore, the surface sensor 42 used in the first embodiment may be used to detect a surface state from which dirt has been removed, and the surface cleaning may be terminated according to the detection result.

  When the object to be treated is a resin mold instead of a mold, a temperature sensor for detecting the temperature of the resin mold is further provided, and the temperature of the resin is controlled by controlling the plasma irradiation time by this temperature. Radiation can be performed while preventing the temperature from rising above the softening temperature. It is also possible to employ such a configuration.

  In the above embodiment, the mold is exemplified as the object to be processed, but the object to be processed is not particularly limited. It can be used for polishing, hydrophilic treatment, water repellency treatment, coating treatment, etc. on an arbitrary object such as an ophthalmic lens, a contact lens, or an optical lens.

Next, an example of the plasma irradiation apparatus is shown.
FIG. 3A is a sectional view on the axis showing the configuration of the plasma irradiation apparatus 310. The plasma irradiation device 310 emits plasma from the front opening end 4a of the high heat resistance insulator 4 made of ceramics. A substantially cylindrical metal outer conductor 2 with a narrowed tip forms an outer shell portion of the coaxial cavity R. The outer conductor 2, the insulator 4, and the metal plasma material gas introduction pipe 1 are all formed in a cylindrical shape so as to be coaxial with each other, and the insulator 4 and the plasma material gas are disposed around this axis. The introduction pipe 1 is located. The outer conductor 2 and the plasma material gas introduction pipe 1 are electrically connected (conductive) in the vicinity of the variable mechanism 6.

  The inlet 1a of the plasma material gas inlet tube 1 is disposed at the rearmost part of the plasma irradiation device 310, while the gas outlet 1b of the plasma material gas inlet tube 1 is disposed on the opposite side. A metallic discharge antenna 5 is disposed further in front of the gas outlet 1b. That is, the discharge antenna 5 is fixed to the inner wall of the insulator 4 and is arranged coaxially with the shaft in the insulator 4. The discharge antenna 5 is formed in a ring shape whose peripheral portion is joined to the inner wall of the insulator 4, and has a projection 351 whose central axis protrudes toward the plasma emission side. In the vicinity of the discharge antenna 5, the plasma material gas introduction tube 1 is not provided in the outer direction with respect to the axis, and the following truncated cone-shaped side wall portion 2 a is provided. With this arrangement, the electric field tends to concentrate on the discharge antenna 5. FIG. 3B shows a front view of the discharge antenna 5.

The front portion of the outer conductor 2 is formed from a substantially truncated cone side wall portion 2 a having a through-hole through which the insulator 4 penetrates on the axis. The structure in which the vicinity of the through hole of the side wall 2a is narrowed forward also contributes to concentrating the generated electric field on the discharge antenna 5.
The front end of the coaxially coupled antenna 3 has a loop shape as shown in FIG. The insulator 4 passes through the loop, and at the same time, the plasma material gas introduction pipe 1 passes through the loop.

  The variable mechanism 6 that adjusts the position of the plasma material gas introduction pipe 1 is formed by using a fixing bracket or the like. The variable mechanism 6 allows the plasma material gas introduction pipe 1 to be attached to the inner wall surface of the insulator 4. Guided, the position can be changed in the axial direction (ie in the front-rear direction). The N-type coaxial connector 7 provides an electrical connection interface for connecting a coaxial cable (not shown). This coaxial cable is used to feed microwaves, whereby high-frequency power input from the N-type coaxial connector 7 is transmitted to the coaxially coupled antenna 3. The coaxially coupled antenna 3 radiates microwaves having a predetermined frequency to the coaxial cavity R based on this feeding. At this time, the microwave generates a high electric field in the coaxial cavity R.

  The plasma material gas flowing in from the inlet 1a of the plasma material gas introduction tube 1 passes through the gap s of the discharge antenna 5 and reaches the vicinity of the protrusion tip t of the discharge antenna 5. Since the electric field concentrates in the vicinity of the projection tip t, the plasma material gas can be ionized by this. The ionized state is plasma, which is emitted from the front opening end 4a in accordance with the inflow speed of the plasma material gas.

The above-described coaxially coupled antenna 3 is disposed on a bisector of the entire length (axial length) of the coaxial cavity R. The total length of the coaxial cavity R is set to 3/4 of the above-mentioned microwave guide wavelength λ.
The outer diameter D of the outer conductor 2 and the outer diameter d of the plasma material gas introduction pipe 1 may be, for example, about D = 30 mm and d = 3.2 mm, respectively.
As the plasma material gas, for example, commonly used gases such as air, argon (Ar), oxygen (O ₂ ), hydrogen (H ₂ ), and nitrogen can be used. In the case of the present plasma irradiation apparatus 310, the gas flow rate is suitably about 0.1 to 10 liters / minute.
Further, the power supplied to the coaxially coupled antenna 3 may be about 100 W.

  According to the above configuration, a very compact plasma irradiation apparatus 310 having a total length of about 100 mm can be configured. Such a reformer is much smaller and lighter than the prior art, and is therefore much easier to handle.

  Further, the reflectivity of the microwave with respect to the coaxial cavity R of the coaxially coupled antenna 3 can be minimized by the variable mechanism 6 that adjusts the position of the plasma material gas introduction pipe 1. Normally, the optimum conditions for impedance matching between the cavity and the coaxially coupled antenna differ depending on whether plasma is generated or not. However, if the variable mechanism 6 is used, the optimum impedance matching can be easily performed. Can be achieved.

  The discharge antenna 5 may be made of a metal material that easily emits electrons. In particular, the discharge antenna 5 is preferably made of tungsten mixed with thorium. Further, as shown in FIG. 4-B, the discharge antenna 5 made of a coiled filament 352 is disposed at the position where the discharge antenna shown in FIG. 3-A is disposed (at the tip of the introduction tube 1 and inside the insulator 4). May be provided. The filament 352 is tungsten mixed with thorium. With this configuration, the filament 352 can be heated by microwaves to effectively emit electrons, and plasma can be easily generated in this portion.

Next, an example using another plasma irradiation apparatus will be described.
FIG. 5 is a diagram showing a configuration of a characteristic main part of a plasma irradiation apparatus according to a specific embodiment of the present invention. A is an external view showing the vicinity of the opening 101, FIG. B is a cross-sectional view along the gas flow path 201, FIG. C is a cross-sectional view showing details of the groove 11 of the electrodes 110A and 110B.

  FIG. Like B, the jig | tool 120 which consists of a cylindrical insulator which has the gas flow path 201 in the center, and the two bent plate-shaped electrodes 110A and 110B are combined. At this time, FIG. As in A, an opening 101 having four sides (surfaces) surrounded by the two electrodes 110A and 110B and the jig 120 is formed. For electrodes 110A and 110B, FIG. Two concave portions 111 each having a width and a depth of 0.5 mm are formed on the surfaces facing each other like C, and the concave portion 111 is a groove portion having the length of the long side of the opening 101. The cross section of the recess 111 has a rectangular shape with one side removed. The gas channel 201 has a cylindrical shape in the vicinity of the connecting portion 203 for introducing the gas and a rectangular cross section at the tip portion 202 via the tapered portion 201t. The electrodes 110A and 110B are fixed to the jig 20 with bolts 130A and 130B, respectively.

  When a voltage is applied by connecting the electrodes 110A and 110B to an AC power source and a gas for generating plasma is passed through the gas flow path 201 of the jig 120 to the opening 101, a negative potential is applied to the electrodes 110A and 110B. In the concave portion 111 on the formed side, electrons emitted by the hollow cathode discharge collide with the gas, and plasma is generated with high density. The plasma generated by this hollow cathode discharge rides on the gas flow and is irradiated from the opening 101. Thereby, plasma is efficiently irradiated to the narrow area | region which faced the opening part 101 of the to-be-processed object.

  6 is a perspective view for explaining the shapes of the electrodes 110A and 110B and the jig 120. FIG. A is a perspective view before assembly, FIG. B is a perspective view after assembly. FIG. Like A, the groove part 11 of the electrode 110 </ b> B is a series of grooves corresponding to the longitudinal direction of the opening 101. The groove 111 of the electrode 110A is formed in the same manner. The tip 202 of the gas flow path 201 of the jig 120 is shown in FIG. As shown in A, it is rectangular. The jig 120 has a protruding portion 211 at the upper part of the tip end portion 202 of the gas flow path 201, and a recess 210A for assembling the electrode 110A. Moreover, it has the recessed part 210B for attaching the electrode 110B similarly. FIG. As in B, a rectangular opening 101 is formed by the inner surface of the protruding portion 211 of the jig 120 and the electrodes 110A and 110B.

  7 is a diagram for explaining the shape of the jig 20 in detail. FIG. B is a front view, FIG. C is FIG. FIG. 7 is a cross-sectional view in the direction of arrow C of FIG. D and FIG. Each E is shown in FIG. It is sectional drawing of D and E arrow direction in B. As shown in FIG. 6, the jig 120 is provided with a protruding portion 211 ahead of the rectangular tip portion 202 of the gas flow path 201 in the rectangular parallelepiped having the gas flow path 201, and is a recess for assembling the electrodes 110 </ b> A and 110 </ b> B. 210A and 210B are provided, and a connecting portion 203 for introducing gas is provided. FIG. C, 7. D and 7. As shown to E, the shape of the gas flow path 201 is cylindrical shape in the vicinity of the connection part 203 which introduce | transduces gas, and has become the rectangular front-end | tip part 202 via the taper part 201t.

  In FIG. 7, the holes for assembling the bolts 130A and 130B and the threads of the connecting portion 203 for introducing gas are omitted. Further, the assembly of the electrodes 110A and 110B is not limited to that using one bolt 130A and 130B, respectively. For example, any known technique such as providing a washer and a bolt for adjusting the gap width of the opening 101 in the vicinity of the rectangular tip 202 of the gas flow path 201 can be added or replaced. FIGS. 5 to 7 show a “plasma generating portion” which is a main part of the plasma irradiation apparatus. By incorporating this into the plasma irradiation apparatus, the plasma irradiation apparatus enables various processings. Can be configured. At this time, as shown in FIGS. 5 to 7, the jig 120 fixing the electrodes 110 </ b> A and 110 </ b> B is fixed by any means, the power source is connected, and the gas supply system is connected to the connection portion 203. It corresponds to the practice of the invention. For the convenience of explanation, a diagram with “opening facing upward” is shown, but it is natural that the present invention includes a configuration for generating downflow plasma that emits plasma downward.

  In the configuration of FIG. 5, an opening is formed by combining two electrodes with a jig 120 made of an insulator having a gas flow path. For example, as shown in FIG. 8, only two electrodes 110C and 110D are formed. In this case, the opening 101 may be formed. In the configuration of FIG. 8, a recess is formed on the surfaces of the electrodes 110C and 110D that form the opening 101 facing each other. When the recess is a continuous groove, the groove (recess) is formed like a star so as to correspond to the star shape of the opening 101. Note that the shape of the jig having the gas flow path, the method for fixing the jig and the electrode, and the method for connecting the electrode and the power source are arbitrary.

  In addition, the shape of the opening is shown in FIG. As shown in FIG. A stripe shape having a wide portion like B may be used. FIG. When the width of the opening varies depending on the location as in B, the number of concave portions formed on the facing surface of the electrode in the wide portion is increased as necessary.

  In FIG. 5, the plasma generating gas is introduced from below and the workpiece is disposed on the upper side of the opening 101. However, the direction of the opening, that is, the plasma emission direction is upward. Not limited. FIG. 5 shows an embodiment for explaining the main part of the present invention, and the plasma irradiation apparatus may be configured with the openings in the horizontal direction and the downward direction.

  In addition to the embodiments described above, the following modifications can be employed. In the above embodiment, the gas flowing through the plasma irradiation apparatus flows a rare gas such as argon, nitrogen gas, hydrogen gas and reactive gas, and plasma is generated by glow discharge of these mixed gases. The gas flowing through the plasma irradiation device is a rare gas such as argon, nitrogen gas, hydrogen gas and reactive gas, and these gases are stably generated and reacted at the outlet of the plasma irradiation device. The reactive gas radical may be generated by flowing a reactive gas. In this way, the plasma is stably generated without being affected by the reactive gas. Further, since dissociation of the reactive gas is suppressed, molecular radicals of the reactive gas can be efficiently generated, and the generated radicals are suppressed from being affected by the flow rate and type of the reactive gas.

  When the glow port is used by bringing the irradiation port of the plasma irradiation device close to the object to be processed, the concentration of electrons and ions is high, surface modification of the outermost surface of the material such as nitriding, and ion assist such as etching with high directivity It is effective for processes that require Conversely, if the irradiation port of the plasma irradiation apparatus and the object to be processed are kept away from each other and the downflow region is used, only the radicals can reach the surface of the object to be processed, so that the surface is not damaged by ions. It is effective for cleaning and film deposition processing.

  In addition, when the power applied to the plasma irradiation apparatus is a pulse, there are few electrons and ions and many radicals exist during a period in which no power is applied. Therefore, even if the distance between the irradiation port of the plasma irradiation apparatus and the object to be processed is close, the ratio of radicals to ions and electrons can be controlled by controlling the duty ratio of the applied pulse, and the object can be maintained with a high radical density. Can be executed.

  The apparatus of the present invention can be used for polishing, cleaning, hydrophilic treatment, water repellency treatment, coating treatment, etc. on the surface of an object.

The block diagram of the plasma processing apparatus which concerns on Example 1 of this invention. The block diagram of the plasma processing apparatus which concerns on Example 2 of this invention. Sectional drawing on the axis | shaft of the plasma irradiation apparatus of Example 3 Front view of discharge antenna provided in plasma irradiation device Front view of coaxial coupling antenna provided in plasma irradiation device Sectional drawing on the axis | shaft of the plasma irradiation apparatus which concerns on another Example Configuration diagram of a discharge antenna showing another example The block diagram of the principal part of the plasma irradiation apparatus which concerns on Example 3 of this invention. The perspective view (2.A) before an assembly for demonstrating the shape of electrodes 110A and 110B and the jig | tool 120, and the perspective view (2.B) after an assembly. 2. A plan view (3.A), a front view (3.B) and a front view (3.B) of the jig 120 as viewed from the front end 202 side of the gas flow path 201; Sectional view in the direction of arrow C of A (3.C), 3. Sectional drawing of D and E arrow direction in B (3D and 3.E). The figure which shows another electrode shape (opening part shape). The figure which shows another electrode shape (opening part shape).

Explanation of symbols

1: Plasma material gas introduction pipe 1a: Introduction port 1b: Gas blowout port 2: Outer conductor 2a: Side wall portion of substantially frustoconical shape (front portion of outer conductor 2)
3: Coaxial coupling antenna 4: Insulator 4a: Front opening end 5: Discharge antenna 6: Variable mechanism 7: N-type coaxial connector R: Coaxial cavity 40: Glass substrate 310: Plasma irradiation device 351: Protrusion 352: Discharge antenna 101: Openings 110A and 110B: Electrodes 11: Recesses or grooves 101: Openings 120: Jigs made of an insulator 130A, 130B: Bolts 201: Gas flow paths 201t: Tapered portions of gas flow paths 202: Tips of gas flow paths 203: Connection part 210A, 210B: Recessed part for assembling electrodes 110A, 110B 211: Projection part

Claims (4)

In a plasma processing apparatus that processes an object with plasma,
A plasma irradiation apparatus for irradiating the surface of the object with plasma;
A posture control device for controlling a plasma irradiation posture of the plasma irradiation device;
A position control device for controlling the irradiation position of the plasma on the object surface;
A radical measurement device for measuring a radical density irradiated by the plasma irradiation device;
A first control device for controlling a plasma generation amount by the plasma irradiation device according to the radical density measured by the radical measurement device;
A plasma processing apparatus. In a plasma processing apparatus that processes an object with plasma,
A plasma irradiation apparatus for irradiating the surface of the object with plasma;
A posture control device for controlling a plasma irradiation posture of the plasma irradiation device;
A position control device for controlling the irradiation position of the plasma on the object surface;
An environmental condition measuring device for measuring an environmental condition comprising a surface condition of the object or a concentration of a reaction product;
A plasma processing apparatus, comprising: a second control device that controls an irradiation time by the plasma irradiation device according to a measurement value by the environmental state measurement device. An environmental condition measuring device for measuring an environmental condition comprising a surface condition of the object or a concentration of a reaction product;
The plasma processing apparatus according to claim 1, further comprising: a second control device that controls an irradiation time of the plasma irradiation device in accordance with a measurement value of the environmental state measurement device.   An imaging device for imaging the object; determining a region to be irradiated with plasma from an image captured by the imaging device; controlling the posture control device and the position and posture device; and irradiating the region with plasma The plasma processing apparatus according to any one of claims 1 to 3, further comprising three control devices.

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