JPH03237304A - Thin film manufacturing device - Google Patents

Abstract

PURPOSE:To manufacture a thin film which is stable at all times by measuring the wavelength dependency characteristic of the transmissivity or reflection factor of the formed thin film, monitoring the peak wavelength obtained from its wavelength data, and holding its value at a constant value. CONSTITUTION:The light emitted by a light source 14 passes through a viewing port 13A and enters a vacuum chamber and the light passes through a substrate 11 and a thin film 12, passes through a viewing port 13B and exits, and then passes through a condenser lens 15. The obtained passing light 17 is inputted to a variable wavelength scanning type monochromater 18 to make a scan with many wavelength light beams obtained by interference operation and measure their transmissivity values, and data on their wavelengths are sent to an arithmetic controller 19. The controller 19 detects and stores a wavelength value regarding target film thickness. Then a power source 5 for sputtering or motor 20 for carrying is so controlled that the measured peak value data equals the target value at all times.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a thin film production apparatus, and in particular, the present invention relates to a thin film production apparatus, and in particular, the production of thin films having the same thickness by controlling the film formation rate to a constant value based on the constant peak wavelength of interference colors. The present invention relates to a thin film manufacturing apparatus for manufacturing a thin film.

[Conventional technology]

For example, in conventional continuous thin film production equipment, even if the thin film production conditions such as discharge power, discharge current, or substrate conveyance speed are kept constant and the film is deposited on the substrate, the usage of the target decreases as the use of the target progresses. There was a problem that the film formation speed changed depending on the amount of electric power (integrated electric energy). Conventionally, three methods have been considered when performing correction and control to keep the film formation rate constant in order to eliminate such problems. The first method is to insert a dummy substrate for film thickness monitoring at an appropriate timing, measure the film formation rate with this dummy substrate, and then feed back to the discharge power or discharge current to correct these values.The second method is to The third method uses an optical film thickness monitor, etc. to monitor and correct the film thickness during or after film formation, and the third method uses a laser film thickness meter to measure and control the film thickness. This is a method of performing correction.

[Problem to be solved by the invention]

However, each of the conventional methods has the following problems.

In the first method, the monitor board must be set frequently, which is troublesome, productivity decreases due to the need to insert the monitor board, and furthermore, monitoring is not performed during the actual process, making the monitoring results unreliable. There was a problem with low gender. The second method is that a film thickness measurement mechanism, such as a two-wavelength optical film thickness meter that uses interference, must have a measurement mechanism and a correction mechanism because the purpose is to determine the film thickness itself. Furthermore, there is a problem in that a certain wide area must be monitored in order to calculate the film thickness. In the third method, the laser film thickness meter is an expensive light source, and there is a problem in that the cost of the entire device increases.

In order to solve the above-mentioned problems, it is an object of the present invention to provide a measurement and correction mechanism that can be easily executed in-process and has high reliability, and to always maintain the same wavelength by keeping the wavelength corresponding to the extreme value of interference color constant. It is an object of the present invention to provide a thin film manufacturing apparatus capable of manufacturing a thin film having a certain thickness, and also capable of establishing automation of the thin film manufacturing process simply and at low cost.

[Means to accomplish the task]

The thin film manufacturing apparatus according to the present invention includes a measuring device for measuring wavelength-dependent characteristics of optical transmittance or reflectance of a thin film having light-transmitting properties fabricated on a substrate, and a transmittance or reflectance measured by the measuring device. an extreme wavelength detection means for detecting a wavelength corresponding to an extreme value in the wavelength-dependent characteristic of reflectance; and a control means for controlling thin film manufacturing conditions so that the wavelength detected by the extreme wavelength detection means is constant. It consists of

In the thin film production apparatus according to the present invention, in the above-described apparatus configuration, when the substrate is transparent or semi-transparent, the measuring device is configured to measure the wavelength-dependent characteristic of the transmittance, and when the substrate is opaque, the measuring device is configured to measure the wavelength-dependent characteristic of the reflectance. characterized in that it is configured to measure a dependent characteristic.

The thin film manufacturing apparatus according to the present invention is characterized in that, in the above-described apparatus configuration, the measuring device includes a variable wavelength scanning monochromator, or a spectrometer and a detection circuit including a photodiode array.

[Effect]

In the thin film production apparatus according to the present invention, for example, when a transparent thin film is produced on a transparent substrate, when the substrate and thin film are irradiated with white light, the transmitted light is affected by the difference in refractive index between the substrate and the thin film layer, and the difference in the interface between the substrate and the thin film layer. Its presence causes an interference effect, and the wavelength-dependent characteristic of transmittance has at least one extreme value (maximum value or minimum value), so it is necessary to control the wavelength corresponding to this extreme value to always be constant. By keeping the film formation rate constant, the thickness of the thin film produced is kept constant. The same thing can be done using reflected light. Therefore, in the present invention, the wavelength-dependent characteristic of optical transmittance or reflectance is measured by a measuring device, the wavelength corresponding to the extreme value in the wavelength-dependent characteristic is detected by the extreme value detection means, and the detected wavelength is determined by a predetermined value. The control means corrects the predetermined conditions for forming the thin film based on the deviation etc. so that the wavelength is maintained at the wavelength of , and controls the film forming rate.

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a continuous type thin film manufacturing apparatus showing an embodiment of the thin film manufacturing apparatus of the present invention. In this thin film manufacturing apparatus, a large number of thin film substrates are manufactured by continuously supplying substrates and performing thin film processing. be able to.

In FIG. 1, reference numeral 1 denotes a long vacuum container, and this vacuum container 1 is provided with, for example, four gate pulps 2 that can be opened and closed.
There are three vacuum chambers IA inside.

IB and IC are formed. Vacuum chamber IA is a load rotor chamber, vacuum chamber 1B is a sputtering chamber, and vacuum chamber IC is an unload lock chamber.

Vacuum pumps 3A, 3B, and 3C are installed in each vacuum chamber to evacuate each vacuum chamber to a required degree of vacuum. Further, a cathode 4 equipped with a target is disposed in the vacuum chamber IB in which sputtering is performed, and a sputtering power source 5 that supplies the required discharge power (discharge current) is connected to the cathode 4.
is connected.

A substrate is supplied to the vacuum container 1 having the above structure from the outside on the left side in the figure. The substrate is supported by a tray 6, and the substrate is placed on the tray 6 so that the thin film processing surface of the substrate appears at the top in FIG. The tray 6, ie the substrate, advances in the direction shown by arrow 7. Therefore, the substrate carried into the vacuum container 1 is
The vacuum chambers are moved in the order of 1A→IB-IC, and the gate pulp 2 existing between the vacuum chambers is opened and closed each time. Although a transport device for moving the substrate in the direction of arrow 7 is not shown in FIG. 1, transport devices well known in the art may be used. For example, an electric motor is used as means for driving the conveyance device.

In the above configuration, a thin film is formed on the upper surface of the substrate in the vacuum chamber IB where sputtering is performed.

In the present invention, when a transmission method is adopted in the measurement/correction mechanism described later, the substrate needs to be transparent or semitransparent. This is not the case when a reflection method is adopted. Further, in the present invention, the thin film formed on the substrate must be transparent or semitransparent, such as ITO.

In the thin film production apparatus according to the present invention, the measurement/correction mechanism that controls the film formation rate to be constant in order to produce thin films having the same thickness is installed at a location where, for example, in the continuous thin film production apparatus described above, the thin film is produced on the substrate. It is any place after the process that is performed. Therefore, the measurement/correction device is, for example, a vacuum chamber I
B or vacuum chamber IC, and further vacuum chamber IC
It can also be placed in a subsequent process. In addition, measurement and
As long as it is configured to perform correction, it can be performed at any location in vacuum or in the atmosphere.

Next, a measurement/correction mechanism for keeping the deposition rate constant and producing thin films of the same thickness in the thin film production process for the substrate will be explained. As a principle for keeping the film formation rate constant, the present invention utilizes keeping the peak top of interference color constant.

Here, keeping the peak top of the interference color constant means that when transmitting light or reflecting light is applied to a substrate on which a thin film is formed, multiple peaks (maximum values or minimum values) obtained due to the wavelength dependence of the transmitted light or reflected light should be kept constant. This means that the wavelength value of one of the peaks is kept constant. On the substrate after deposition,
For example, when white light is irradiated in an optical measuring system as shown in FIG. 2, which will be described later, the transmitted light or reflected light can obtain characteristics as shown in FIG. 5 based on the interference effect of light. In FIG. 5, the horizontal axis represents wavelength (nm), and the vertical axis represents transmittance (%). In the case of this characteristic example, the substrate is a glass substrate, the refractive index n of the glass substrate is 1.5, and the refractive index n2 of the transparent thin film is 2.0. As shown in FIG. 5, when the film thickness is 140 nm, characteristic A1 can be obtained, and in this case, the peak of characteristic A1,
That is, the value of the wavelength corresponding to the maximum value (peak top) is a certain fixed value X when the refractive index (nl*n2) is constant. becomes. However, when the thickness of the thin film changes, the value of the peak wavelength changes. For example, when the film thickness is reduced by 5 nm, the characteristics become as shown in A2, and the wavelength corresponding to the peak is
. -20.

Moreover, when the film thickness increases by 5 nm, the characteristics become like A3, and the wavelength corresponding to the peak is X. It becomes +20.

When there is a difference in the thickness of the thin film in this way, a shift occurs in the value of the peak wavelength due to the effect of interference. On the other hand, a constant value of the peak wavelength means that the film thickness is constant under the condition that the refractive index of the thin film or the like is constant. Therefore, the measurement/correction mechanism according to the present invention is configured to control the various conditions of thin film production so that the peak wavelength is kept constant at a required value, and this means that the various conditions are substantially changed. Even if this happens, it means that control is performed so that the film formation rate is always kept constant.

Next, a measurement system with a feedback mechanism according to Fig.
A first embodiment of the correction mechanism will be described. As mentioned above, this measurement/correction mechanism measures the peak wavelength of the interference color of transmitted light and controls the value of this wavelength to be constant, thereby keeping the film deposition rate constant and achieving the same film thickness. This is for producing thin films. Therefore, the measurement target is the peak wavelength of the interference color, and the correction target is the sputtering discharge power (
discharge current) or substrate transport speed.

In FIG. 2, reference numeral 10 denotes a vacuum chamber, and the vacuum chamber 10 is provided at a required location in the vacuum container 1 that satisfies the above-mentioned conditions. A glass substrate 11 on which a thin film 12 is formed is placed in a vacuum chamber 1.
0, it is moved in the direction shown by arrow 7 by a transport device (not shown). Tray 6 shown in FIG.
The illustration of is omitted. Viewing boats 13A and 1 are provided on two mutually opposing walls of the vacuum chamber 10, respectively.
3B is provided, and a light source 14 is provided outside the viewing boat 1.3A.
A condenser lens 15 is disposed outside B together with two front and rear light shielding plates 16. For example, white light emitted from the light source 14 passes through the viewing boat 13A, enters the vacuum chamber 10, passes through the substrate 11 and the thin film 12, passes through the viewing boat 13B, exits outside, and passes through the condenser lens 15. do.

The transmitted light 17 thus obtained is input to a variable wavelength scanning monochromator 18.

Reference numeral 19 denotes an arithmetic and control unit, which is composed of a computer or the like. The variable wavelength scanning monochromator 18 scans a large number of wavelengths of light generated by interference in the light 17 transmitted through the substrate 11 and the thin film 12, measures their transmittance, and outputs data regarding the wavelengths. The arithmetic and control unit 19 inputs the wavelength data output from the variable wavelength scanning monochromator 18 and processes this wavelength data. In data processing in this arithmetic control bag ff1f19, the characteristics shown in FIG. 5 regarding the required film thickness (target film thickness) are calculated, the value of its peak wavelength is detected, and this is stored. In subsequent measurements, the peak wavelength is monitored, and a correction control signal is fed back to the sputtering power source 5 or the transport motor 20 so that the peak wavelength always matches the target wavelength and remains constant. Data on the measured peak wavelength is output from the arithmetic and control unit 19. Feedback of the control signal is performed to at least one of the sputtering power source 5 and the transport motor 20 as necessary.

According to the above configuration, the light is output from the light source 14 and the substrate 11
The sputtering conditions or substrate conveyance speed are controlled so that the peak top of the interference color of the light transmitted through the thin film 12, that is, the wavelength value of the light that becomes the maximum value, is constant A, so that it is set as a target in advance. If the film thickness is given as data, thin films of the same thickness can be produced. In particular, the continuous thin film production apparatus shown in FIG. 1 can continuously produce a large number of thin film substrates having the same thickness.

FIG. 3 shows a second embodiment of the measurement and correction mechanism.

This configuration also employs a transmission method, and the same elements as those in the configuration explained in FIG. 2 are denoted by the same reference numerals, and detailed explanation thereof will be omitted. In this measurement/correction mechanism, a combination of a spectrometer 21 and a detection circuit 22 is used instead of the variable wavelength scanning monochromator 18. The spectroscope 21 is, for example, a prism, and the detection circuit 22 includes a photodiode array, an ammeter connected to each diode, and a load resistor. Output from the light source 14,
The light 17 that has passed through the substrate and the thin film is separated into light of each wavelength according to its refractive index by a spectroscope 21, and each light is sent to a detection circuit 2.
2 corresponding diodes. Since the light of each wavelength is attenuated according to its transmittance when passing through the substrate 11 and thin film 12, the detection circuit 22 can obtain wavelength data corresponding to the transmittance of each wavelength. This wavelength data is given from the detection circuit 22 to the arithmetic and control unit 19, where the value of the peak wavelength is determined. The subsequent correction control operation is the same as in the embodiment shown in FIG. 2 above. The measurement/correction mechanism according to this embodiment can perform real-time measurement and wavelength monitoring, and by narrowing the wavelength interval of the photodiode array in the detection circuit 22, the accuracy as a monitor can be improved.

FIG. 4 shows an embodiment of a measurement/correction mechanism having a reflection type configuration. The configuration according to this embodiment is employed when the substrate 11 is opaque and only the thin film 12 is transparent or semitransparent.

In the illustrated example, the structure of the vacuum chamber is omitted. light source 1
4 is installed on the side where the thin film 12 is located at a required angle.

The light 17 emitted from the light source 14 hits the thin film 1 at a specific angle.
2, is reflected by the front and back surfaces of the thin film 12, and is input to, for example, a wavelength variable scanning monochromator 18. In this case, it goes without saying that the configuration of the spectrometer 21 and detection circuit 22 described above can be adopted. In this embodiment, measurement and correction control is executed to keep the peak top of the interference color constant based on a relationship diagram similar to that shown in FIG. 5 between wavelength and reflectance. The other configurations are the same as in each of the embodiments described above. This embodiment is particularly effective when the substrate is opaque.

FIG. 6 shows an example of the wavelength dependence of transmittance when a transparent thin film is formed on a glass substrate. This wavelength dependent characteristic 3
0, the refractive index of the transparent thin film used is about 2.0, and the refractive index of the glass substrate is about 1.5. By using this wavelength dependent characteristic 30, the peak top (maximum value)
The above-described control can be performed by setting the target wavelength of 533 nm as a constant wavelength. In the conventional method of determining film thickness from transmittance characteristics, it is necessary to have a wide wavelength range (several peaks) for monitoring transmittance, but in the case of the present invention, the wavelength range at the top of the peak 1 point (533
Since it is sufficient to monitor wavelengths around 100 nm), the configuration of the monitor can be simplified. Furthermore, when a plurality of peak tops exist, any peak top can be used.

Furthermore, a peak-bottom (minimum value) 32 also exists in the wavelength-dependent characteristic 30 in FIG. The present invention can be constructed in the same manner even if peak bottoms are used instead of the peak tops described above.

Although the description of each of the above embodiments is based on the assumption that the apparatus is a continuous type thin film fabrication apparatus as shown in FIG. 1, the present invention can be similarly applied to a type of thin film fabrication apparatus in which the substrate does not move. Of course. In this case, the peak top of the thin film after deposition is measured, and the measured data is used for subsequent thin film fabrication. Furthermore, in the case of the discontinuous method, the substrate transport speed is not subject to correction.

Further, in the above embodiments, an example was explained in which the present invention was applied to a single-sided sputtering apparatus, but it goes without saying that the present invention can also be applied to a double-sided sputtering apparatus. Furthermore, the present invention can be applied to other thin film production apparatuses other than sputtering apparatuses.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the wavelength-dependent characteristics of the optical transmittance or reflectance of the thin film to be formed are measured, and the peak wavelength obtained from the wavelength data is monitored. Since the thin film production conditions are controlled so that the peak wavelength is maintained at the required constant value, changes in the film deposition rate caused by the amount of target used are suppressed, and thin films with the same thickness are always produced stably. can do. Furthermore, since the thin film manufacturing conditions are corrected and controlled so that the peak wavelength is constant, the thin film can be manufactured at low cost with a simple configuration. Furthermore, since measurement and correction can be performed in-process, film thickness control is highly reliable.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing a continuous thin film production apparatus according to an embodiment of the present invention, FIG. 2 is a configuration diagram showing a first embodiment of a measurement/correction device, and FIG. A block diagram showing the second embodiment, Fig. 4 is a block diagram showing the third embodiment of the measurement/correction device, Fig. 5 is a graph showing the relationship between film thickness, wavelength, and transmittance, and Fig. 6 is the transmittance. 3 is a graph showing an example of wavelength dependent characteristics of . [Explanation of symbols] 1... Vacuum vessel 2... Gate valve LA, IB, IC, 10... Vacuum chamber 3A, 3B, 3C... Vacuum pump 4... ...Cathode 5 ...Sputtering power source 6 ...Tray 11 ...Substrate 12 ...Thin film 14 ...Light source 18 ... Variable wavelength scanning monochromator 19... Arithmetic control unit 20... Transport motor 21... Spectrometer 22... Detection circuits 3A, 3B, 3C: Vacuum pump 6: tray

Claims (5)

[Claims] (1) A measuring device that measures the wavelength-dependent characteristics of the optical transmittance or reflectance of a thin film with light-transmitting properties fabricated on a substrate, and the wavelength-dependent characteristics of the transmittance or reflectance measured by this measuring device The method is characterized by comprising: an extreme wavelength detection means for detecting a wavelength corresponding to an extreme value of , and a control means for controlling the conditions for producing the thin film so that the wavelength detected by the extreme wavelength detection means is constant. thin film fabrication equipment. (2) The thin film manufacturing apparatus according to claim 1, wherein when the substrate is transparent or semitransparent, the measuring device is configured to measure wavelength dependent characteristics of transmittance. (3) The thin film manufacturing apparatus according to claim 1, wherein when the substrate is opaque, the measuring device is configured to measure wavelength dependent characteristics of reflectance. (4) The thin film manufacturing apparatus according to any one of claims 1 to 3, wherein the measuring device includes a variable wavelength scanning monochromator. (5) The thin film manufacturing apparatus according to any one of claims 1 to 3, wherein the measuring device includes a spectroscope and a detection circuit including a photodiode array.