JP2003082462A - Vacuum film deposition system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vacuum film deposition system capable of depositing a thin film and a multilayer film of high film thickness uniformity in a substrate surface. SOLUTION: The vacuum film deposition system has a sputtering device which sputters a film surface by irradiating a film deposition surface of a substrate with ions. In addition, it comprises a light irradiation unit which collects the irradiation light emitted from a light source and irradiates the substrate with it, a light reception unit which receives the reflected light or the transmitted light from the substrate, and a signal processor which analyzes the light quantity of the signal light received by the light reception unit and calculates the optical film thickness of the film deposited on the substrate, and the concentration distribution of the sputter ions on the substrate surface is changed based on the optical film thickness calculated by the signal processor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum film forming apparatus, and more particularly, to a vacuum film forming apparatus capable of forming a thin film having a uniform film thickness in a plane.

[0002]

2. Description of the Related Art Generally, a thin film or a multilayer film as an optical material obtained by vacuum film formation is required to have a uniform film thickness within its surface. In particular, DWDM (Dens
e Wavelength Division Multiplexing: wavelength division filter for communication system (so-called DW)
DM filter) is composed of a multilayer film in which several tens to several hundreds of dielectric thin films having different refractive indexes are alternately laminated on a glass substrate whose surface is highly accurately polished, and the optical film thickness of each thin film is set to a design value. DWDM that has a certain optical characteristic by exactly matching with
It is required to obtain a filter and make the film thickness of the multilayer film formed on the substrate uniform in the plane to increase the yield.

[0003]

However, in the conventional vacuum film-forming apparatus, it is possible to make the density of the film-forming substance flying onto the surface of the film-forming substrate provided in the vacuum film-forming chamber uniform within the surface of the substrate. Since it is difficult, there is a problem that the in-plane film thickness of the thin film after film formation becomes non-uniform.

FIG. 6 is a view for explaining the film thickness distribution within the substrate surface of the optical multilayer film for DWDM filter formed by using the conventional vacuum film forming apparatus, and on a special glass substrate having a diameter of 95 mm. Alternating dielectric thin film with different refractive index
The multilayer film of layers formed, the difference between the film thickness t _r at each point of the distance r from the substrate center, and the thickness t ₀ of the multilayer film at the substrate center Δt
This is a plot of (= t _r −t ₀ ).

The thickness of this multilayer film is thickest in the center of the substrate and gradually decreases toward the outer periphery of the substrate, and the difference in thickness between the central portion and the outermost periphery of the substrate is ± 1. %
Has become. This film thickness difference is due to the uniformity of the film thickness required for the current production of multilayer films for DWDM filters (±
However, there is a problem that the manufacturing yield of the DWDM filter decreases.

The present invention has been made in view of the above problems, and an object thereof is to enable the formation of a thin film or a multi-layer film having a high film thickness uniformity within the substrate surface. It is to provide a vacuum film forming apparatus.

[0007]

In order to achieve such an object, the present invention provides a vacuum film-forming apparatus according to claim 1, wherein a film-forming substance supplying means and a substrate holding means are provided in a vacuum film-forming chamber. A vacuum film forming apparatus for forming a film by supplying a film forming substance onto the surface of the substrate held by the substrate holding means,
It is characterized in that the film surface formed on the substrate is provided with sputtering means for irradiating ions to sputter the film forming substance in the irradiation region, and the film is formed while sputtering the film forming surface.

The invention described in claim 2 is the same as claim 1.
In the vacuum film forming apparatus described in the paragraph 1, the ions are oxygen ions.

The invention described in claim 3 is the same as claim 1
In the vacuum film forming apparatus described in the paragraph 2, the light irradiation means for converging the irradiation light emitted from the light source and irradiating it onto the substrate, and the light receiving means for receiving the reflected light or the transmitted light from the substrate. And signal processing means for analyzing the light quantity of the light received by the light receiving means as a signal and calculating the optical film thickness of the film formed on the substrate.

The invention described in claim 4 is the same as claim 3
In the vacuum film forming apparatus according to, the sputtering means includes an ion distribution control means, the ion distribution control means, based on the calculation result of the optical film thickness by the signal processing means,
It is characterized in that the distribution of ions irradiated on the surface of the substrate is changed.

The invention described in claim 5 is the same as claim 1.
In the vacuum film forming apparatus described in any one of 1 to 4, the substrate holding unit is configured to be rotatable, and the substrate held by the substrate holding unit is rotated for film formation.

The invention according to claim 6 is the same as claim 1.
5. The vacuum film forming apparatus according to any one of items 1 to 5, wherein the vacuum film forming apparatus includes an ion irradiation unit that irradiates the film forming substance supplied to the film forming surface of the substrate with ions.

Furthermore, the thin film or the multilayer film according to claim 7 is formed by the vacuum film forming apparatus according to any one of claims 1 to 6.

[0014] [Detailed Description of the Invention]

BEST MODE FOR CARRYING OUT THE INVENTION The vacuum film forming apparatus of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a diagram for explaining an example of the structure of a vacuum film forming apparatus of the present invention. A vacuum film forming chamber 101, electron guns 102A and 102B and a target holder provided in the vacuum film forming chamber. A film forming substance supply device including 103A and 103B, a substrate holding unit 104, and a substrate holding unit 10.
For irradiating the film-forming surface of the substrate 105 held on the substrate 4 with ions to sputter a part of the film-forming substance formed,
The vacuum film forming chamber 101 is provided with a sputtering device including an ion source 106A and an ion source controller 106B.
The inside can be maintained at a high vacuum by a vacuum pump 107 provided outside the vacuum film forming chamber.

A motor 108 is installed outside the upper center of the vacuum film forming chamber 101, and the rotary shaft 10 of the motor 108 is installed.
9 extends through the vacuum film forming chamber 101, and the substrate holding unit 104 is attached to the tip thereof. Therefore,
The substrate 105 held by the substrate holding unit 104 is the motor 1
It is possible to rotate by rotating 08.

A transparent window 110 is provided in a part of the inner bottom surface of the vacuum film forming chamber 101, and the vacuum film forming chamber 101 is provided.
Light from a light source such as a halogen lamp provided outside is guided to the light irradiating section 111 by the optical fiber 112 and is irradiated to the measurement point on the substrate. in this case,
The light irradiation unit 111 is fixed to the moving shaft 113, and the moving shaft 1
The drive mechanism 114 can move 13 in the horizontal direction. Thereby, the irradiation point (measurement point) of the irradiation light on the substrate 105 can be set at an arbitrary position in the radial direction of the substrate 105.

On the back surface side of the film formation surface of the substrate 105,
A light receiving portion 115 for receiving the transmitted light transmitted through the substrate 105 is arranged, and the light receiving portion 115 is provided on the substrate 105.
It is attached to a movable shaft 117 which is movable in the horizontal direction by a drive mechanism 116 in parallel with the. Therefore, the light receiving unit 1
The light receiving position 15 can be freely selected above the substrate 105 so as to coincide with the irradiation point of the irradiation light in the radial direction of the substrate 105.

Since the phase difference of the signal light changes with the optical film thickness of the thin film being monitored due to the interference action of the reflected lights generated on the front and back surfaces of the thin film when the irradiation light passes through the thin film, The optical film thickness can be calculated by utilizing the change in light intensity.

The DWDM filter has, for example, a thickness of 10
170-190nm thickness on a special glass substrate of about mm
Ta ₂ O ₅ thin film and Si having a thickness of 240 to 270 nm
About 80 to 260 layers are formed by alternately stacking thin films of O ₂ and, for example, after forming the above-mentioned multilayer film on a disc-shaped special glass substrate having a diameter of about 95 mm, the special glass substrate is cut. It is manufactured by a method of forming a large number of square chips of 1.4 × 1.4 mm ² .

To form the multilayer film for the DWDM filter, first, in the target holders 103A and 103B of the film forming material supply device in the vacuum film forming chamber 101, a target serving as an evaporation source for Ta ₂ O ₅ thin film vapor deposition and SiO _{2 are} deposited. A target which is a vapor deposition source for thin film vapor deposition is installed. Next, the substrate holder 10
4 holds the substrate 105 made of special glass, and the vacuum pump 10
7, the inside of the vacuum film forming chamber 101 is evacuated to a vacuum of 1 × 10 ⁻⁵ Pa or less, and then the electron guns 102A and 102B are operated while the motor 108 rotates the special glass substrate 105 at a rotation speed of 1000 rpm. Then, the film-forming substance is made to fly from the target toward the substrate 105 made of special glass.

The sputtering apparatus composed of the ion source 106A and the ion source control unit 106B irradiates oxygen ions from the ion source 106A onto the film-forming surface of the substrate 105, and the energy of the irradiated ions is near the surface of the substrate 105. And the film-forming substance in the region near the surface of the already-formed multilayer film is removed at a sputtering rate depending on the density.

That is, the multilayer film being formed is formed by the film forming substance supplied from the film forming substance supplying device to increase the film thickness, and a partial region in the vicinity of the already formed film surface. However, the film is formed while simultaneously advancing the process of being sputtered by the oxygen ions irradiated from the ion source 106A to reduce the film thickness.

Therefore, when a film thickness difference occurs on the surface of the substrate 105 depending on the density distribution of the film forming material supplied from the film forming material supplying device, the ion is adjusted under the condition that the film thickness difference is canceled. By performing sputtering with oxygen ions emitted from the source 106A, a multilayer film having a uniform in-plane film thickness distribution can be obtained.

Further, the oxygen ion irradiation apparatus 120 causes the oxygen ions to collide with the particles of the film-forming substance toward the substrate 105 to promote the migration of atoms and molecules adhering to the surface of the substrate 105. It is used for the purpose of improving the filling rate and the adhesion rate of the thin film formed on the substrate.

In this configuration example, oxygen ions are adopted as ions for sputtering the surface vicinity region of the multilayer film to be formed, but the ion species is not limited to oxygen, and it is suitable for sputtering. Can be used.

Further, in the present configuration example, the sputtering apparatus constituted by the ion source 106A and the ion source control section 106B provided for the purpose of sputtering and the purpose of improving the film quality of the multilayer film to be formed are provided. Although the ion irradiation device 120 is provided, the same or two
When it is possible to use different kinds of ions and the energy and density of ions necessary for sputtering and the energy and density of ions necessary for improving the film quality are compatible, only one ion irradiation device May be provided to achieve the above two purposes.

In addition to such film formation, the light irradiation section 111
Irradiation light L ₀ emitted from is irradiated onto the substrate 105 of special glass on which the multilayer film is formed, and the transmitted light is received by the light receiving unit 115. The received transmitted light is guided to the signal processing device 119 by the optical fiber 118, and the signal processing device 119 uses, as the signal light, the light of the wavelength to be analyzed among the light in the wavelength region of the light included in the transmitted light. The signal light L is signal-processed, a physical quantity corresponding to the optical film thickness of the film being formed is calculated, and the multilayer film is formed while monitoring the optical film thickness of the thin film being formed.

As described above, if there is no ion irradiation from the ion source 106A provided in the vacuum film forming apparatus of the present invention, the multilayer film to be formed will have a nonuniform film thickness within the plane. In the vacuum film forming apparatus of the present invention, in order to eliminate this film thickness nonuniformity, sputtering is performed corresponding to the film thickness difference between the in-plane reference point and each in-plane point.

Since the sputtering rate by ions depends on the ion density at each point in the plane, the ion source 1
It is necessary to know the optimum ion density distribution near the surface of the substrate 105 to be achieved by 06A.

FIG. 2 is a diagram for explaining a measurement system of the irradiation ion distribution near the substrate of ions irradiated from the sputter ion source provided in the vacuum film forming apparatus of the present invention. The oxygen ion sensor 22 is arranged at an interval of, and the substrate holder 2 is irradiated with light from the ion source 23.
The oxygen ion concentration coming to 1 is monitored.

The oxygen ion concentration distribution thus monitored varies depending on the shape of the irradiation end of the ion source 23. For example, when the shape is a simple cylindrical shape, it is shown in FIG. As described above, there is a distribution in which the density is high in the central part of the substrate and thin as it approaches the outer peripheral part.

FIG. 3 is a diagram for explaining the effect of the irradiation end shape of the ion source provided in the vacuum film forming apparatus of the present invention.
In FIG. 3A, the irradiation end 31 has a relatively large inner diameter d ₁
Is a diagram for explaining an ion density distribution in the case of a simple cylindrical shape having, FIG. 3 (b), in the case of a simple cylindrical shape having a relatively small inner diameter d ₂ of the irradiation end 34 shaped It is a figure for demonstrating ion density distribution.

As shown in this figure, the ion density distribution changes depending on the shape of the irradiation edge, and while FIG. 3 (a) shows a relatively broad distribution, in FIG. 3 (b), the central portion of the substrate is shown. The ion density is high and a thin ion density distribution is obtained in the outer peripheral portion of the substrate.

Corresponding to such a difference in ion density distribution, in the ion irradiation system shown in FIG. 3A, the in-plane film thickness difference of the multilayer film 33 formed on the substrate 32 is calculated. It is not possible to realize sufficient sputtering to cancel the sputtering, resulting in a multilayer film having a thick film thickness in the central part of the substrate and a thin film thickness in the peripheral part.

On the other hand, in the ion irradiation system shown in FIG. 3 (b), the sputtering of the multilayer film 36 formed on the substrate 35 is sufficiently canceled so that the in-plane film thickness difference can be canceled out. The multilayer film has a uniform film thickness distribution from the central portion to the outer peripheral portion.

In the above example, the ion irradiation end has a simple cylindrical shape and the inner diameter is changed. However, the shape is not limited to this, and the ion density distribution can be changed. Any shape can be used as long as it can be properly set.

FIG. 4 is a diagram for explaining an example of the internal structure of the ion source provided in the vacuum film forming apparatus of the present invention. A quartz chamber 41 is provided inside the ion source 40, and a quartz chamber 41 is provided inside the quartz chamber. A substantially conical irradiation angle control section 42 for controlling the distribution of sputter ions is provided at the tip of the provided cylindrical section 44, and the gas introduced from the gas introduction port 43 is supplied to the grid 45A. It is ionized by the electric field formed between 45B. That is, by setting the opening angle α of the irradiation angle control unit 42, the ion concentration distribution near the substrate surface can be set to a distribution required for the uniformity of the film thickness.

The result of monitoring the optical film thickness by the above-mentioned signal processing device is fed back to the irradiation angle control unit 42, the opening angle α of the irradiation angle control unit 42 is adjusted, and the film thickness measurement result after film formation is displayed. On the basis, if the opening angle of the irradiation angle control unit 42 is set to be optimal for canceling the nonuniformity of the film thickness, it is possible to control a constant ion concentration distribution.

FIG. 5 is a view for explaining the in-plane film thickness uniformity of a multilayer film formed by the vacuum film forming apparatus of the present invention and the conventional vacuum film forming apparatus, and is formed on a substrate having a diameter of 95 mm. ,
180 nm thick Ta ₂ O ₅ thin film and 250 nm thick
Of SiO ₂ thin film and a multilayer film formed by laminating overlapping 200 layers alternately of a difference Delta] t (= t between the thickness t ₀ of a thickness t _r and the substrate center from the center of the substrate at the location of the radius r It is a result of obtaining _r −t ₀ ).

In the case of a multilayer film formed by a conventional vacuum film forming apparatus, the difference in film thickness within the plane is ± 1% at the maximum.
The maximum film thickness difference of the multilayer film formed while performing ion sputtering under the optimum conditions in the vacuum film forming apparatus of the present invention is ± 0.02%. Uniformity of inner film thickness is realized.

[0042]

As described above, according to the present invention,
A vacuum film forming apparatus that includes a film forming material supply device and a substrate holding unit in a vacuum film forming chamber and supplies a film forming substance onto the surface of a substrate held by the substrate holding unit to form a film Since the sputtering apparatus for irradiating the surface with ions to sputter the film surface is provided, it is possible to provide a vacuum film forming apparatus capable of forming a film having high in-plane film thickness uniformity.

Further, a light irradiating section for converging the irradiation light emitted from the light source and irradiating it onto the substrate, a light receiving section for receiving reflected light or transmitted light from the substrate, and a signal received by the light receiving section. A signal processing device for analyzing the light amount of light to calculate the optical film thickness of the film formed on the substrate, and based on the optical film thickness calculated by the signal processing device, Since it was decided to change the concentration distribution of sputtered ions, the ion concentration distribution is controlled so that the in-plane film thickness non-uniformity of the multilayer film, which changes moment by moment during film formation, is controlled, and a higher in-plane film thickness is obtained. It is possible to provide a vacuum film forming apparatus capable of forming a film having a uniform thickness.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a configuration example of a vacuum film forming apparatus of the present invention.

FIG. 2 is a diagram for explaining a concentration distribution measuring system in the vicinity of a substrate of sputtered ions emitted from an ion source provided in the vacuum film forming apparatus of the present invention.

FIG. 3 is a diagram for explaining the effect of the irradiation end shape of the ion source provided in the vacuum film forming apparatus of the present invention.

FIG. 4 is a diagram for explaining a configuration example of an ion source provided in the vacuum film forming apparatus of the present invention.

FIG. 5 is a diagram for explaining in-plane film thickness uniformity of a multilayer film formed by the vacuum film forming apparatus of the present invention and a conventional vacuum film forming apparatus.

FIG. 6 is a DWD formed by using a conventional vacuum film forming apparatus.
It is a figure for demonstrating the film thickness distribution in the board | substrate surface of the optical multilayer film for M filters.

[Explanation of symbols]

21 substrate holder 22 Oxygen ion sensor 23 Ion source 31, 34 Irradiation end 32, 35 substrate 33, 36 Multi-layer film 40 ion source 40 41 Quartz chamber 42 Irradiation angle control unit 43 gas inlet 44 Cylindrical part 45A, B grid 101 vacuum deposition chamber 102A, B electron gun 103A, B target holder 104 substrate holder 105 substrate 106A ion source 106B Ion source control unit 107 vacuum pump 108 motor 109 rotation axis 110 transparent window 111 Light irradiation unit 112 optical fiber 113 axis of movement 114 drive mechanism 115 Light receiving part 116 Drive mechanism 117 Moving axis 118 optical fiber 119 Signal processing device 120 ion irradiation device

Claims (7)

[Claims] 1. A vacuum film forming apparatus comprising a film forming material supply unit and a substrate holding unit in a vacuum film forming chamber, and supplying a film forming substance onto a surface of a substrate held by the substrate holding unit to form a film. In the above method, a sputtering means for irradiating the film surface formed on the substrate with ions to sputter the film forming substance in the irradiation region is provided, and the film is formed while sputtering the film forming surface. Vacuum film forming equipment. 2. The vacuum film forming apparatus according to claim 1, wherein the ions are oxygen ions. 3. A light irradiation means for collecting irradiation light emitted from a light source and irradiating it onto the substrate, a light receiving means for receiving reflected light or transmitted light from the substrate, and the light receiving means. 3. The vacuum film formation according to claim 1 or 2, further comprising: a signal processing unit that performs an analysis process of a light amount of the received light as a signal and calculates an optical film thickness of a film formed on the substrate. apparatus. 4. The sputtering means comprises an ion distribution control means, and the ion distribution control means changes the ion distribution irradiated on the substrate surface based on the calculation result of the optical film thickness by the signal processing means. The vacuum film forming apparatus according to claim 3, wherein the vacuum film forming apparatus is provided. 5. The vacuum apparatus according to claim 1, wherein the substrate holding unit is configured to be rotatable, and the substrate held by the substrate holding unit is rotated to form a film. Membrane device. 6. The vacuum film forming apparatus according to claim 1, further comprising ion irradiation means for irradiating the film forming substance supplied to the film forming surface of the substrate with ions. Vacuum film forming equipment. 7. A thin film or a multilayer film formed by the vacuum film forming apparatus according to claim 1.