KR20140136154A

KR20140136154A - Method and apparatus for real-time measuring deposition thickness and uniformity during deposition process

Info

Publication number: KR20140136154A
Application number: KR1020130056282A
Authority: KR
Inventors: 서일원; 권기청; 윤명수; 조태훈; 차성덕; 우원균
Original assignee: 광운대학교 산학협력단; (주)원우시스템즈
Priority date: 2013-05-20
Filing date: 2013-05-20
Publication date: 2014-11-28

Abstract

The present invention relates to a method and an apparatus for measuring thickness of a deposited film. The apparatus measures the thickness of the deposited film by measuring intensity of plasma light emission generated during a plasma deposition process. The intensity of the plasma light is measured after the plasma light, generated during the deposition process, penetrates the film deposited on a substrate and a portion of the substrate. The apparatus calculates the thickness of the deposited film based on the intensity of the plasma light. Unlike the prior apparatus for measuring thickness of a deposited film, the apparatus of the present invention measures thickness of multiple spots of the deposited film at the same time and in real time during a deposition process. Therefore, uniformity of the deposited film can be monitored in real time.

Description

METHOD AND APPARATUS FOR MEASURING DEPOSITION Thickness and Uniformity in Real Time in a Deposition Process

The present invention relates to a method and an apparatus for measuring a deposition thickness by measuring the intensity of a plasma light source generated during a plasma deposition process. Specifically, unlike the conventional thickness measuring apparatus, And more particularly, to a method and apparatus for monitoring uniformity in real time by measuring various positions simultaneously.

The present invention relates to the development of control technology for a deposition process using a plasma emission source (2013, Joint Technology Development Project (No. C0036739), Development of Low Cost Atmospheric Pressure Plasma Doping Source Technology for Crystalline Solar Cell Process Renewable Energy Technology Development Project Information and Communication Media Industry Technology Development Project No. 20113020010080), and 'Development of High Density Plasma Technology for Inorganic Thin Film Deposition for Ultra-Fine Semiconductor and Flexible Display Processes' (Industrial Source Technology Project No. 10041926) This is the result of performance.

Conventional plasma deposition equipment such as a sputtering process is subjected to a deposition process and the thickness thereof is measured separately using a thickness measuring device. Since such a thickness measurement can not be performed in real time while the sputter deposition process is being performed, there is the inconvenience that the thickness of the deposition must be separately measured after completion of the deposition process and the sample must be moved. It also requires a large working space and can cause damage to the measuring substrate. In addition, many samples are required to proceed with the thickness measurement, so that the economical problem can not be excluded.

Measuring methods in existing measurement equipment can be classified into ultrasonic, laser, radiation, and magnetic field methods. The most commonly used method is thickness measurement using laser and ultrasonic waves. These conventional measuring devices are expensive and have a fixed life span and require separate maintenance.

Also, existing measuring equipment can not measure multiple positions at the same time, so it is inconvenient to check the uniformity and it takes relatively long measurement time.

In addition, since the thickness and uniformity of the substrate can not be confirmed during the process, it is difficult to increase the defect rate and to study a new process.

Accordingly, the present invention can provide a method and an apparatus capable of precisely controlling process control and uniformity by shortening the time required for the plasma deposition process such as sputtering process in an industrial field or a laboratory by measuring the deposition uniformity as well as measuring the deposition thickness during the deposition process .

First, the principle of the present invention will be outlined as follows.

The present invention provides a method and apparatus for measuring deposition thickness by measuring the intensity of a plasma light source generated during a plasma deposition process. Unlike conventional thickness measuring instruments, it is possible to monitor uniformity in real time by measuring in real time during the process and measuring various positions at the same time. The problem to be solved by using this measurement equipment is to contribute to the reduction of time, cost reduction, and defect rate by proceeding the deposition process and the deposition thickness measurement at once. In sputtering deposition equipment, which is widely used in display fields such as OLED, LCD, etc., it is possible to facilitate oxide layer thickness change and physical property change according to the distribution of oxygen flow in the research and development of various fields.

In a plasma deposition process, a plasma is generated by atomically ejecting an atom by hitting a target in a state where some gas atoms (or molecules) in the gas are ionized and separated into + ions and - electrons, Ar and process gases (SiH ₄ , TEOS, NH _4, H _2, O _2, etc.) _, which are used to make films or are inert gases by RF power, are ionized to maintain the plasma state and ionized silicon oxide deposition gas ) Are used to deposit SiO _2, Si _x N _y amorphous silicon thin films, etc., which are plasma deposited thin films, by reacting with Si ions and oxygen ions in a high temperature substrate.

The present invention relates to a method and an apparatus for measuring the intensity of a direct plasma light source by measuring the intensity of a direct plasma light source, unlike the conventional deposition thickness measuring apparatus, and also includes diagnosing the uniformity of the deposition thickness. Thus, it is possible to shorten the process time and to perform real-time monitoring during the process. In addition, the uniformity of the substrate during the process can be confirmed by measuring various positions on the substrate on which the thin film is deposited.

Next, a measuring method and an apparatus according to the present invention will be described in detail.

A method for real time measurement of deposition thickness and uniformity in the deposition process according to the first aspect of the present invention will be described below.

In a typical sputtering process (in other words, sputtering) during a plasma deposition process, a plasma is generated to start a deposition process. At this time, the intensities of the wavelengths of the light generated by the plasma are measured in real time by the spectroscope (spectrometer) or the spectrometer.

If the thickness of the deposited film is large, the intensity of the light will be measured to be small. Therefore, the absolute value of the light intensity is measured and compared with the previously set light intensity value to calculate the currently deposited film thickness. In one embodiment, the thickness value is calculated by comparing the intensity value measured in the current process with the thickness value according to the light intensity value of the plasma light source stored as a lookup table. In another embodiment, the relationship between the light intensity value and the deposition thickness may be set in advance, and the thickness can be calculated using this relationship.

In addition, since the measured value of the light intensity varies depending on the type and thickness of the substrate, it is preferable to calculate the thickness of the deposited thin film after correcting the type and thickness of the substrate put into the process.

A susceptor in which a substrate is placed may be provided with a through hole for detecting plasma light, and a heat-resistant optical fiber resistant to heat may be provided in the susceptor to allow light to be incident on the spectrometer. Alternatively, a spectrometer may be provided directly under the through hole formed in the susceptor to measure the plasma light.

By forming a plurality of susceptor through holes, it is preferable to measure the intensity of the plasma light simultaneously at various positions of the substrate. By doing so, the uniformity of the deposition over the area of the substrate can be confirmed.

Of course, if a plurality of susceptor through holes are formed, it is preferable to dispose optical fibers for each through hole or to install a spectrometer.

The deposition process control (thin film thickness control) can be performed in real time using the deposited thin film thickness and uniformity data measured during the deposition process. That is, if the thickness measured during the process has not yet reached the preset thickness, the process parameters (oxygen flow rate, substrate temperature, RF power, etc.) are adjusted to continue the process until the set thickness is reached The deposition proceeds.

During the deposition process, the thin film thickness is measured in real time by the substrate position and the uniformity of the thin film is measured and analyzed. For example, it is possible to diagnose the change in thickness and physical properties according to the oxygen flow rate and to utilize it for the deposition of oxide thin films having a large area and high uniformity.

When the uniformity falls within the allowable range, the process is completed. If the uniformity is not appropriate, the alarm is sounded, the process is stopped, the process conditions are changed again, and the process is performed again.

The more detailed operation of the method according to the present invention described above will be further clarified by the description of the apparatus of the present invention described below.

An apparatus for measuring deposition thickness and uniformity in real time in a deposition process using plasma according to the second aspect of the present invention is configured as follows.

A sputtering apparatus is provided in a process chamber configured to maintain an internal vacuum by a vacuum pump system. A sputtering apparatus is installed in the vacuum chamber. A target made of an evaporation material is disposed in the vacuum chamber. A susceptor including a hot plate is provided. A substrate to be vapor-deposited is mounted on the susceptor. A plurality of through holes are formed in the susceptor, and optical fibers are respectively inserted into the through holes.

On the other hand, as another embodiment, it is possible to directly detect the light of the plasma light source by providing the spectrometer directly below the through holes without providing optical fibers in the plurality of through holes of the susceptor. Therefore, the optical fiber is deleted in this embodiment.

In the susceptor, a constant temperature uniformity must be maintained. If a plurality of through holes are formed, the uniformity of the temperature can be broken by the holes. In order to solve this temperature uniformity problem, a method of drilling a through hole at a relatively small diameter of 0.2 mm to 1 mm is used in one embodiment, and a method of welding glass or quartz to the through hole is used in another embodiment, In another embodiment, the susceptor is made of a transparent material.

When forming the small-diameter through-hole, if the optical fiber or spectrometer is to be inserted into this hole, since the hole is small, a hole with a small diameter or a hole with a larger diameter capable of insertion of the optical fiber or spectrometer It is preferable to form them together.

The optical fiber is connected to a spectrometer located outside the chamber. When pulling the fiber out of the chamber, it should be through a vacuum tube feedthrough to keep the vacuum inside the chamber and allow the fiber to come out. The spectrometer is connected to a computer.

Now, the constituent elements and actions of the present invention will be described in detail as follows.

A processing chamber is required, which is used as a vacuum chamber to maintain a vacuum state for the generation of a stable plasma and a problem about a contamination source except evaporation materials during the deposition process. In the process chamber, several components are used for vacuum formation, such as vacuum pumps and O-rings, flanges, and gaskets.

A spectroscopy or spectrometer is a spectroscopic instrument using a monochromator or polychromator connected to a transducer that converts the intensity of the light source to an electrical signal and is used to measure the intensity of light emitted from the plasma.

A susceptor with a heater - The temperature of the substrate during the deposition process is an important factor in determining the deposition rate and the phase of the thin film. To control the temperature of the substrate (room temperature to> 400 ° C), a susceptor is used in conjunction with a device control unit and a computer.

Substrate - Substrate should be selected considering the heating temperature and mechanical and optical properties of the substrate, which should be cleaned before the sputtering process.

The target and the RF electrode-target are materials that are deposited on a substrate such as glass as a transparent electrode material mainly in a vacuum sputtering apparatus. At present, a target having a sintered density of 99% of the theoretical density is commercialized and used. The RF electrode is used to generate plasma from a predetermined process gas (hydrogen, ammonia siren) by applying RF power in PECVD or the like.

Vacuum feedthrough for optics - Connect the optical fiber inside the chamber to an external spectrometer or connect it to a computer for equipment control outside the spectrometer inside the chamber. ).

Mass flow controller - used to accurately and reliably measure and control the mass flow rate of a gas using heat capacity and convective heat transfer characteristics.

Optical fiber - An optical fiber that has high refractive index glass in the center and low refractive index glass in the outer part, so that light passing through the center glass is totally reflected in the fiber. It has very little energy loss and is used to deliver a plasma light source to the spectrometer. Also, heat resistant optical fiber can be used to withstand substrate, susceptor, and chamber temperature, and an optical fiber including chemical resistance can be used to withstand the chemical reaction of plasma and gas.

Equipment control and analysis computer - Controls the hot plate temperature in conjunction with the temperature controller, displays the intensity of the light coming from the plasma and the spectrometer on the screen for the user to see, And then stores and outputs the analyzed results.

Hereinafter, the operation of the present invention will be described.

In the thus configured apparatus of the present invention, when the deposition process is started, a plasma is generated between the target and the substrate, and sputtering deposition starts to be performed. A plasma is generated on the surface of the substrate by a plasma, and at the same time, a plasma light source passes through the deposition film and the substrate to pass through the through hole (or transparent susceptor) formed in the susceptor. Since the optical fiber is provided in the through hole, the light of the plasma light source is detected by the spectrometer outside the chamber through the optical fiber, and its intensity is measured. The output of the spectrometer is transmitted to a computer to estimate the thickness of the deposited film in the current process by a predetermined method within the computer. In addition, since a separate optical fiber is provided for each of the plurality of through holes, the film thickness is estimated at various places on the substrate to monitor the deposition uniformity.

(Ar, oxygen, nitrogen, process gas or the like) is injected by applying a pump to the exhaust end in a plasma processing chamber such as a sputtering machine or a PECVD apparatus to generate a low vacuum and a high vacuum state, . Process parameters such as oxygen flow rate, temperature, and RF power are important factors in thin film deposition. Therefore, an MFC, a substrate temperature controller, an RF power source, and a computer are needed to control this. In particular, the susceptor must transmit the plasma light because a fiber optic or spectrometer must be installed below the susceptor with the heater and temperature controller. Drilling a large hole in the susceptor portion to transmit the plasma light may result in an uneven temperature uniformity across the substrate. In order to solve such a temperature uniformity problem, there is a method of drilling a hole with a relatively small diameter of 0.2 mm to 1 mm, or a method of filling or welding a heat insulating material such as glass or quartz between the holes. Alternatively, there is an alternative to fabricating the susceptor with a transparent material.

A typical example of the deposition process equipment using plasma is a sputtering apparatus. The sputter deposition method (sputtering) uses a Ar gas and an O ₂ gas to generate a plasma. When the cations in the plasma generated ions reach the target with sufficient energy, the target atoms are removed and the oxide is deposited on the substrate. During deposition, the deposition thickness is measured using the apparatus of the present invention.

The principle of thickness measurement will be described. Referring to FIG. 6, the transmitted light is differently transmitted depending on the thickness of the material to be deposited and the constants n and k. To do this, we need to know the n and k values of the deposition material. The measurement of the deposition thickness is carried out by the principle of canceling and reinforcing the incident light and the transmitted light by wavelength.

The overall uniformity of the substrate is confirmed by measuring the thickness of the thin film by position. As another example, plasma-enhanced chemical vapor deposition (PECVD) is performed when a plasma is discharged by using nitrogen and SiH ₄ gas (diluted with Ar) as a reaction gas on a substrate during deposition of a SiN _x thin film. In the case of PECVD, the thickness and the uniformity of the deposited thin film are measured by the reduced strength as in the case of the sputtering method.

As described above, the present invention can be applied to all deposition apparatuses in which plasma is generated.

The environment of the deposition thickness and uniformity measurement according to the present invention will be summarized as follows.

- thickness meter:

o Spectrometer or spectroscopy,

o Optical fiber,

o Circuitry to control process conditions of parameters (oxygen flow rate, substrate temperature, RF power, etc.) that affect the film thickness and physical properties

- Thickness Measurement

- Uniformity

- Applicable to all plasma deposition process equipment

- Typically, various oxide thin films (transparent conductive oxides (TCO), etc.) deposited in the case of sputtering can be applied

ITO (Indium Tin Oxide)

o IGZO (Indium Gallium Zinc Oxide)

o BZO (Boron Doped Zinc Oxide)

o Aluminum Doped Zinc Oxide (AZO)

300 nm to 1100 nm, 900 nm to 1700 nm

&Lt; Wavelength Resonance >

0.01 nm to 10 nm

According to the present invention, uniformity of the substrate can be confirmed during the deposition process and thickness measurement simultaneously and by measuring various positions on the substrate on which the thin film is deposited, thereby shortening the process time and real-time monitoring during the process . According to the present invention, by monitoring the thickness of a deposited material in real time, it is possible to control precise process conditions and diagnose uniformity in R & D and industrial sites, and to improve the quality of a deposited substrate by using a sputter.

1 is a flow diagram of a method for real-time measurement of deposition thickness and uniformity in a deposition process in accordance with the present invention.
2 is a schematic view showing a first embodiment of an apparatus for measuring deposition thickness and uniformity in real time in a deposition process according to the present invention;
3 is a schematic view showing a second embodiment of an apparatus for measuring deposition thickness and uniformity in real time in a deposition process according to the present invention.
Figures 4 and 5 are schematic diagrams illustrating two alternative embodiments of a susceptor;
6 schematically shows the thickness measurement principle used in the present invention.

Hereinafter, specific embodiments of the above-described method and apparatus will be described with reference to the drawings. First, FIG. 1 is a flowchart showing a processing procedure of an embodiment of the method of the present invention.

First, the plasma is generated in the sputtering process, and the deposition process is started (10).

At this time, the intensity of light is measured by a spectroscope (spectrometer) or a spectrometer using a light source operated by a plasma, and the thickness is calculated according to the intensity (20). Specifically, in one embodiment, the thickness is calculated by comparing the intensity value measured in the current process with the thickness value corresponding to the light intensity value of the plasma light source stored as a lookup table. In another embodiment, the relationship between the light intensity value and the deposition thickness may be set in advance, and the thickness can be calculated using this relationship. In this step 20, the thickness is measured at various portions of the substrate to monitor the uniformity of the film deposition.

In another embodiment, since the measured value of the light intensity varies depending on the type and thickness of the substrate, the thickness of the deposited thin film may be calculated after correcting the type and thickness of the substrate introduced into the process.

The following steps 30 to 80 show the step of performing the deposition process control (thin film thickness control) in real time using the deposited thin film thickness and the uniformity data measured during the deposition process. That is, if the thickness measured during the process has not yet reached the preset thickness, the process parameters (oxygen flow rate, substrate temperature, RF power, etc.) are adjusted to continue the process until the set thickness is reached And the deposition proceeds (30).

Next, it is judged whether or not the uniformity is deposited with a proper uniformity within an allowable range (40). If the uniformity is appropriate, the deposition process is completed. (50) If the uniformity is not proper, the alarm sound is notified (60), the process is stopped (70), the process condition is changed again (80) Proceed with the process.

2 schematically shows the configuration of one embodiment of the apparatus of the present invention.

A sputtering device is installed in a process chamber configured to maintain internal vacuum by a vacuum pump system (200). A target 17 made of an evaporation material is provided in the upper part of the vacuum chamber 100 and a hot plate (not shown) for raising the temperature of the substrate with a certain space below the target 17 The susceptor 120 is installed.

A deposition target substrate 110 is mounted on the susceptor 120. A plurality of through holes 125 are formed in the susceptor 120 and optical fibers 150 are inserted into the through holes 125, respectively. In the susceptor 120, a uniform temperature uniformity must be maintained. If a plurality of through holes 125 are formed, the uniformity of the temperature can be broken by the holes. In order to solve such a temperature uniformity problem, a method of drilling the through hole 125 at a relatively small diameter of 0.2 mm to 1 mm (see FIG. 4), or a method of filling the hole 125 with a heat insulating material such as glass or quartz, And a method of manufacturing the susceptor 120 with a transparent material (see FIG. 5) can be considered.

4, the small diameter through hole 125 is formed downward from above the susceptor 120, and a groove 127 having a larger diameter is formed from the bottom to the top. The lower groove 127 is a groove for installing the spectrometer 210 and the narrow narrow hole 125 is a small diameter of 0.2 mm to 1 mm in order to uniformly maintain the temperature of the susceptor 120 As shown in Fig.

5, the susceptor 120 is made of a transparent material, and a spectrometer 210 is provided on the lower surface of the susceptor 120 so that the plasma light source 130 is transmitted through the spectrometer 210 without piercing another through hole, .

The optical fiber 150 is connected to the spectrometer 210 outside the chamber 100. When the optical fiber 150 is taken out of the chamber 100, the optical fiber 150 is allowed to pass through the vacuum tube feedthrough 220 in order to allow the optical fiber to come out while maintaining the vacuum inside the chamber. The spectrometer 210 is connected to the computer 230. 1 shows a plasma light source that virtually indicates that the light of the generated plasma 160 is transmitted through the substrate 110 and enters the susceptor 120. Reference numeral 140 denotes a plasma light source 180 denotes a power source (DC or RF), 190 denotes a mass flow controller, and 240 denotes a process gas.

In the apparatus of the present invention configured as described above, when the process starts, a plasma 160 is generated between the target 170 and the substrate 110 on the susceptor 120 to start sputter deposition. The deposition film 140 is formed on the surface of the substrate 110 by the plasma 160 and the plasma light source 130 is penetrated through the deposition film 140 and the substrate 110 to form the through holes (125). Since the optical fiber 150 is provided in the through hole 125, the light from the plasma light source 130 is detected by the spectrometer 210 outside the chamber 100 through the optical fiber 150, and the intensity thereof is measured. The output of the spectrometer 210 is transmitted to the computer 230 so as to estimate the thickness of the deposition film 140 in the current process by a predetermined method in the computer. In addition, since a separate optical fiber 150 is provided for each of the plurality of through holes 125, the uniformity of the deposition is monitored by estimating the film thickness at various places on the substrate 110. This is described in the description of FIG. And the operation of the other components are the same as those in a general plasma deposition process, so a detailed description thereof will be omitted.

Fig. 3 schematically shows the configuration of another embodiment of the apparatus of the present invention. 2 except that the spectrometer 210 is directly installed below the through hole 125 instead of the optical fiber being installed in the through hole 125 of the susceptor 120, Thereby directly detecting the light of the light source 130. Therefore, the optical fiber 150 is deleted in this embodiment. Since the operation of the embodiment of FIG. 3 is substantially the same as that described in FIG. 2, its description is omitted.

Claims

A method for measuring the thickness of a film deposited on a substrate during a plasma deposition process,
The plasma light intensity generated after the plasma light generated in the deposition process passes through the film deposited on the substrate and at least a part of the substrate is measured,
And measuring the deposition thickness of the film based on the measured plasma light intensity value.

The method according to claim 1, wherein the deposition film thickness is determined by a deposition process in which a deposition film thickness value is compared with a strength value measured in a current process while a deposition film thickness value corresponding to a light intensity value of the plasma light source is stored as a look- A method for measuring the thickness and uniformity of a deposited film in real time.

2. The method according to claim 1, wherein the thickness is calculated by calculating a deposition thickness of the deposition film thickness and uniformity in a deposition process by previously setting a relational expression between the plasma light intensity value and the deposition thickness, .

4. A method according to any one of claims 1 to 3, further comprising monitoring the uniformity of the film deposition by measuring the thickness of the deposition film at various portions of the substrate, How to measure.

4. The method according to any one of claims 1 to 3, wherein variations in the measured values of light intensity occur depending on the type and thickness of the substrate, so that after correcting the type and thickness of the substrate introduced into the process, Wherein the thickness and uniformity of the deposited film are measured in real time during the deposition process.

4. The method according to any one of claims 1 to 3,
If the thickness measured during the process has not yet reached the preset thickness, the process parameters are adjusted so that the process continues, and the deposition continues until the set thickness reaches the set thickness,
It is judged whether or not the uniformity is deposited with a proper uniformity within the allowable range. If the uniformity is proper, the deposition process is completed. If the uniformity is not proper, the process is further repeated after the process conditions are changed again , A method of measuring the thickness and uniformity of a deposited film in real time in a deposition process.

A susceptor including a hot plate for raising the temperature of the substrate is provided under the target, a target made of the evaporation material is provided in the upper part of the process chamber configured to maintain the internal vacuum by the vacuum pump system, An apparatus for measuring a thickness of a film deposited on a substrate during a deposition process by a plasma deposition apparatus, the susceptor including a substrate to be deposited,
At least one through hole is formed in the susceptor
Wherein the means for measuring the intensity of the plasma light after passing through the through hole of the susceptor and the film deposited on the substrate and the at least one portion of the substrate deposited on the substrate are adjacent to the through hole Wherein the thickness and uniformity of the deposited film are measured in real time in a deposition process.

The apparatus according to claim 7, wherein the plasma light intensity measuring means is a spectrometer connected to the optical fiber provided in the through hole of the susceptor and a spectrometer to which the optical fiber is connected. .

8. The apparatus according to claim 7, wherein the plasma light intensity measuring means is a spectrometer provided below the through hole of the susceptor, and measures the thickness and uniformity of the deposited film in real time.

The apparatus of claim 7, further comprising a computer for storing a vapor deposited film thickness measurement value according to a plasma light intensity value as a look-up table and for comparing the intensity value measured in the current process with the current vapor deposition film thickness from the look- Wherein the thickness and uniformity of the deposited film are measured in real time in a deposition process.

The deposition method according to claim 7, further comprising a computer for calculating a vapor deposition film thickness by previously setting a relational expression between the intensity value of the plasma light and the vapor deposition film thickness, A device that measures the thickness and uniformity of the deposited film in real time.

12. The method of claim 10 or 11, wherein the computer comprises means for monitoring the uniformity of the film deposition by measuring the thickness of the deposition film at various portions of the substrate. In real time.

12. A method according to any one of claims 7 to 11, characterized in that the diameter of at least one through hole of the susceptor is from about 0.2 mm to 1 mm, wherein the thickness and uniformity of the deposited film are measured in real time Device.

12. The apparatus according to any one of claims 7 to 11, wherein at least one through hole of the susceptor is filled with a heat insulating material, and the thickness and uniformity of the deposited film are measured in real time.

The apparatus of any one of claims 7 to 11, wherein the susceptor is made of a transparent material, and measures the thickness and uniformity of the deposited film in real time.