KR20030012227A - A manufacturing method of thin film using a rapid photothermal chemical vapor deposition - Google Patents

Abstract

PURPOSE: A method for manufacturing thin film devices using RPCVD(Rapid Photothermal Chemical Vapor Deposition) apparatus is provided to produce high quality SOI(Silicon on Insulator) with low temperature deposition characteristics by applying hydrogenation and RTA(Rapid Thermal Annealing) onto the deposited silicon. CONSTITUTION: After a silicon deposition process in the SOI, a hydrogenation process is applied to the deposited silicon layer so as to remove defects and stress in the silicon film layer. The hydrogenation process includes injecting the furnace with hydrogen gas and heating the furnace at 200-500 degrees C under 0.1-1 Torr so that the injected gas becomes to the plasma state and the silicon film reacts for 10 minutes or to 4 hours. The method further includes applying RTA onto the deposited silicon film.

Description

A manufacturing method of thin film using a rapid photothermal chemical vapor deposition}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a thin film device using a rapid optical heating chemical vapor deposition apparatus, and to fabricate a high quality silicon on insulator (SOI) substrate in which a semiconductor material such as Si is deposited in a single crystal or polycrystalline form using a ceramic substrate as a substrate. In order to achieve a low temperature deposition process using a low temperature deposition using RTCVD, in order to improve the quality of the deposited thin film is characterized in that the hydrogenation and oxidation heat treatment.

Recently, a popular electronic component is a metal-oxide semiconductor field emission transistor (MOSFET). MOSFET is a field effect transistor (FET) that insulates a metal electrode with an oxide film, and can make a very small size and has a low driving voltage and low driving current. It is used as signal control device or signal storage component such as circuit or memory DRAM. There are many types of MOSFETs, but the most common is a complementary metal-oxide semiconductor (CMOS).

As the integration technology of manufacturing components to make the size of the device very small to include as many devices as possible, the length, size, and wiring width of the device become very small and precise. However, CMOS does not provide complete isolation between electrodes, resulting in new parasitic transistors that were not expected by the device. Parasitic transistors have an effect on signal control and signal storage, and many of the parasitic transistors generated by integration increase drive current and generate excessive heat, which reduces the life of electronic components and saves many signal processing errors and stored signals. Caused the disappearance of.

In order to increase the degree of integration, we started to reduce the length and width of the wires connecting the devices, but if the width of the wires is reduced below the intrinsic threshold of the wiring material, delays occur in the signal processing and signal processing It will be late. In addition, high-integration technologies require a variety of conditions, such as fast response speed, low power, and low voltage consumption.

Current integration technologies have faced their limitations, making it difficult to integrate smaller CMOS sizes. Moreover, when thin film technology is being produced at the time of the development of thin film technology as of today, the heat generated by the large number of integrated devices is much higher than that generated by the previous integrated devices. By lowering the performance of the electronic component, the driving voltage cannot be lowered to the voltage level required for the thin film device, and since the transistor electrodes cannot be completely insulated, many errors occur in the signal processing process.

Therefore, a new method has been devised to develop a new high-integration technology to replace CMOS, and the result is a silicon on insulator (SOI). SOI is basically a method of depositing a Si thin film on an insulating layer and making a circuit thereon. The n-type layer and p-type layer required for the base layer are removed to simplify the circuit, and the n-type layer and The photolithographic etch process, which is necessary for making p-type layers, is not necessary, making the manufacturing process relatively simple.

SOI is a form of Si deposited on an insulating substrate. Since the electrode and the electrode are completely insulated, high-speed signal processing is possible and parasitic transistors are not generated, thereby generating very little heat. The quality of SOI is evaluated by the crystal form of Si deposited on the insulating substrate. Si, usually deposited as a thin film, is in amorphous form. Since amorphous Si films are not fast in signal processing, attempts have been made to make the deposited Si into a single crystal epitaxial layer.

There are various methods of manufacturing SOI such as BOSO and BOFT (Epitaxial Layer TRANsfer), Smart Cut and SOS (Silicon on sapphire). The method of improving the quality of the deposited Si is also used.

In order to fabricate the SOS through a multi-step process using RTCVD, a substrate on which Si is to be prepared is first prepared. The substrate used for SOS is sapphire. Sapphire is an alumina single crystal, and in order to make the surface index of Si deposited [001], the surface index of sapphire must be [102], and the surface of the substrate is polished prior to deposition to smooth the surface of the substrate to form a suitable shape for deposition. After the chemical etching, the foreign material on the surface of sapphire is removed, and the surface of the sapphire is cleaned again to be suitable for deposition. Then, Si is deposited using a source gas.

As the source gas, generally, silylene (SiH ₄ ) is used. Increasing the temperature of the reactor to 1000 ° C and injecting SiH ₄ into the reactor at a rate of ₂ sccm (standard cubic centimeter per minute) under a pressure of 0.1torr and H ₂ at 80sccm for 60 minutes, the following reaction occurs: Si is deposited on sapphire.

SiH ₄ + heat-> Si + 2H ₂

Figure 1 shows a TEM photograph of the [110] plane of Si deposited using the above method. As can be seen in the figure, many dislocations occur in the sapphire substrate and the deposition surface of Si below, leading to the middle part of the Si film. Since these defects play a role in deteriorating the electrical characteristics, a process of reducing the defects must be additionally performed.

An object of the present invention is to provide a method for manufacturing an SOI substrate through a low temperature deposition process.

Another object of the present invention is to reduce the defects present in the Si layer of the SOI substrate.

Another object of the present invention is to provide a method for improving the quality of a Si thin film.

Features of the method for manufacturing a thin film device according to the present invention for achieving these objects in the method for manufacturing a thin film device using a rapid photothermal chemical vapor deposition (Rapid photothermal chemical vapor deposition) device; A rapid thermal annealing (RTA) process in which oxygen is injected into the reactor to oxidize the surface of the thin film device and a process of removing the SiO ₂ layer formed by oxidizing the thin film device due to the rapid heat annealing process are performed. It is characterized by being added.

The detailed feature of the present invention, after depositing the thin film device on the substrate, while injecting hydrogen gas (H ₂ ) into the reactor while the pressure of the reactor in the range of 0.1 to 1 torr, temperature 200 to 500 ℃ microwave generation A hydrogenation process is performed prior to the rapid thermal annealing (RTA) process to operate the apparatus to excite the injected hydrogen into a plasma state and react for 10 minutes to 4 hours to remove defects of the thin film device. Is the point.

1A is a structural diagram of RTCVD;

1b shows the internal structure of RTCVD,

2 is an exemplary view showing a state near a substrate;

3a is a TEM picture of a typical SOI,

3b is a TEM photograph of a sample subjected to oxidation heat treatment,

3c is a TEM photograph of a sample subjected to oxidation heat treatment after hydrogenation;

4 is a Raman analysis result graph,

5 is a DLTS measurement result graph,

Figure 6a is a graph of V-C measurement results,

6b is a graph of V-I measurement results.

In the present invention, Si is deposited using rapid photothermal chemical vapor deposition (RPCVD), which is a type of RTCVD. RTCVD consists of a heating part, a vacuum part, and a control part. RTCVD is a CVD method in which a process is performed by heating a reactor with light rays generated from a lamp. RTCVD heats the furnace rapidly so that the rate of temperature rise by heat reaches 300 ° C / s. RPCVD and RTCVD are almost the same way, just that RPCVD is a more advanced RTCVD method. So the difference is that RPCVD not only raises the temperature inside the reactor by light, but also excites atoms or molecules in the reaction gas, lowering the activation energy so that the reaction can occur easily. It is a more advanced feature than the existing technology.

Figure 1a is a block diagram showing the basic structure of the RPCVD according to the present invention. The control unit 10 for controlling the amount and rate of the reaction gas (N ₂ , O ₂ , H ₂ , SiH ₄ ) flowing into the furnace (furnace) and the reaction gas flowing into the reactor using a microwave (microwave) It comprises a microwave generator 20 for exciting in a plasma state, and a heating unit 40 for heating a furnace (furnace).

Although not shown, the reactor is maintained in a vacuum state by the vacuum unit. In the RPCVD according to the present invention, a quartz tube 30 in a transparent form with a lamp is included in the reactor so that light generated from the lamp 44 can be transmitted without loss. Since the quartz tube 30 is transparent, light can be transmitted as it is, and since the melting point is about 1450 ° C., it is very high.

The microwave generator 20 excites hydrogen gas introduced into the reactor into a plasma state by using a microwave having a frequency of 13.56 MHz.

The gas introduced to deposit or heat-treat the thin film is transferred onto the substrate 1 placed in the quartz tube 30. At this time, the lamp 44 uses a halogen lamp that generates light belonging to the near infrared (near infrared) region (wavelength is approximately 1.0㎛), the generated light passes through the quartz tube 30 near the substrate 1 Heat rapidly. A pump (not shown) is attached to the end of the reactor to send gas in the furnace out of the furnace, thereby maintaining the pressure in the reactor at a constant pressure and depending on the deposition conditions. If it is necessary to change the pressure, change the pressure in the reactor. Lamp control unit 43 for controlling the operation of the halogen lamp 44 is a halogen lamp 44 is operated according to the detection result of the pyrometer (42) for detecting the internal temperature of the timer 41 and the reactor. By controlling the time, the temperature inside the reactor is controlled.

1b shows the interior of the furnace of RPCVD. The quartz separation layer 45 is positioned below the halogen lamp 44. It serves to support the lamp located in the upper part of the reactor, and it must be transparent because it needs to transmit the light generated from the lamp. The reaction gas flows in from the front of the arrow of the quartz tube, is deposited on the substrate 1, and then exhausted in the direction of the arrow. In addition, since the pyrometer 42 is connected to the substrate, it is possible to precisely control the temperature. Figure 2 shows the vicinity of the substrate inside the RPCVD. The gas delivered near the substrate is excited by light and deposited on the substrate.

There are a variety of substrates used to produce Si by depositing Si. Although sapphire, which is a single crystal of alumina, may be used, materials such as M ₂ O single crystal, Mullite, AlN single crystal and polycrystal, and glass-ceramic may be used as the substrate. However, Si was deposited in the present invention using a sapphire substrate having excellent quality of the deposited Si thin film.

To deposit Si on a sapphire substrate, a source gas is required. As the source gas, usually, silylene (SiH ₄ ) is used. When the source gas is placed in a furnace and heated, the xylene is separated into hydrogen and Si. The reaction formula is as follows.

SiH ₄ + heat-> Si + 2H ₂

The Si produced by the reaction of xylene with the heat is in the atomic state, but has not yet been deposited on the sapphire substrate, and the reaction gas and the resulting Si atoms cannot transport on the sapphire substrate by themselves, thus transporting the reaction gas and Si to the substrate. I need a gas. There are two types of gases used as carrier gases. Hydrogen (H ₂ ) is used when the temperature of Si deposition is between 750 ° C. and 1000 ° C. or higher, and nitrogen (N ₂ ) is used when the temperature of Si deposition is between 600 ° C. and 700 ° C.

When depositing Si, a single deposition condition may be used, but two or three deposition conditions may be used to optimize the quality of Si. That is, during deposition, temperature and gas inflow rate and pressure can be divided into two, or three kinds can be deposited, and the temperature, pressure, and gas inflow rate can be set without setting the range. It is also possible to use a method of depositing Si within.

Currently, the general method of depositing Si on a substrate to fabricate an SOI is SiC ₄ at a rate of ₂ standard cubic centimeters per minute (Sisc) under pressure of 0.1 torr at 1000 ° C, and H ₂ at 80 sccm for 60 minutes. A single deposition condition is used to grow a Si thin film while injecting it into the reactor.

In the present invention, Si is grown at a temperature of about 800 ° C to 900 ° C and a pressure of 0.5 to 3 torr at a ratio of SiH ₄ and H ₂ to 25 to 40, thereby increasing the quality of the Si film and improving the quality of the Si film. Thermal annealing and hydrogenation processes were added. The hydrogenation process and the RTA process may be performed independently, or the RTA process may be performed after the hydrogenation process.

Injecting hydrogen gas into the reactor for hydrogenation, the output of the microwave generator 20 is 30-90 W, the pressure is 0.1-1torr, the temperature is in the range of 200-500 ℃, the reaction for 10 minutes to 4 hours Let's do it. In the present invention, the hydrogen gas is injected into a preferred method of hydrogenation, and the pressure of the reactor is about 0.2torr, and then the internal temperature is 300 ° C, and the microwave generator 20 is operated to generate 13.56MHz microwaves. The hydrogen is excited in a plasma state and maintained for about 3 hours. The temperature of the reactor is rapidly increased to 600 ° C. through RTA, and oxygen is injected into the reactor while maintaining the temperature for about 1 hour to oxidize the surface of the Si film. Thereafter, the process is completed by removing the SiO ₂ layer formed by oxidizing the Si film due to RTA.

In the present invention, the hydrogenation used is a method of reducing the defect of the Si film through hydrogen injection and heating after the deposition of Si is completed. Hydrogenation is not only a defect near the surface of the Si film, but also inside the Si film. It also eliminates defects and reduces the stresses inherent in Si films.

The RTA used in the present invention may be called oxidative heat treatment. RTA is a method of rapidly heating and heat-treating, which can also be used as an oxidative heat treatment by injecting oxygen, thereby reducing the potential stress (residual stress) acting on the Si film and removing defects. When the heat treatment is performed under the condition of injecting oxygen, the surface Si is oxidized to SiO ₂ by oxygen, so the SiO ₂ layer must be removed by etching.

In order to analyze the difference between the quality of the thin film layer deposited in the present invention and the characteristics of the improved Si film, the Si deposited sample without further processing and Si using only RTA as an additional process were used. The quality of the Si film is compared by mutual analysis with the deposited samples. In order to compare the quality of the Si film, first, the defects present in the Si film are optically analyzed, and then the mechanical properties of the Si film, the concentration of the defects present in the Si film, and the electrical characteristics of the Si film are compared.

First, [110] sections were photographed by transmission electron microscopy (TEM) as an optical method. 3A is a cross-sectional view of a sample obtained by depositing only Si, and FIG. 3B is a sample using only RTA. Comparing the photographs, it can be seen that there are many defects in the interface between the Si film and the sapphire substrate of FIG. 3A, and that the defects are much reduced in FIG. 3B compared to FIG. 3A. Comparing FIG. 3B with FIG. 3C, it can be seen that there are almost no defects at the interface of FIG. 3C.

Raman analysis is performed to measure the mechanical properties and crystallinity of the Si film, that is, the magnitude and crystallinity of the potential stress. Raman analysis is a method of measuring the scattering of the lattice. The width (FWHM: FullWidth at Half Maximum) corresponding to half of the peak is inversely related to the size of the Si grain, which is usually amorphous. (amorphous) is a very wide spread form, the closer to a single crystal (single crystal) the width becomes smaller.

When there is a latent stress on the thin film, the magnitude of the latent stress can be measured by comparing the positions of the peaks measured by Raman analysis. The potential stresses are caused by differences in lattice constants at the interfaces between different materials. Therefore, if the substrate and the thin film deposition material, such as a thin film, the peak generated during Raman analysis of the thin film deposited material appears to move to some extent from the peak generated when the Raman analysis of an object made of pure thin film material. Thus, by measuring the degree of movement of the peak, if the peak is moved a lot of potential stress, the less the degree of movement of the peak is found that less potential stress occurred.

4 is a Raman analysis result of a sample deposited as Si without any additional process, a sample having only RTA as an additional process, and a sample having RTA after hydrogenation. Width (FWHM), which did not have to make any further process corresponds to the peak center of the as grown is about 8.5cm ^-1, if only RTA is 5.08cm ^-1, if both the hydrogenation and the RTA is 4.0cm ^-1 . Therefore, when RTA was performed rather than when no additional process was performed, the quality of Si was improved, and the quality of Si was further improved when RTA was performed after hydrogenation rather than RTA alone.

When the peak position was confirmed, the peak position of bulk Si was 520.9cm ^-1, and the peak position of RTA and RTA after hydrogenation was about 523.2cm ^-1, which was peak of Si grown as deposited. It can be seen that the potential stress is less than the position 523.7cm ^-1 , and it is about 0.44% shifted from the peak position of bulk Si, and it is considered that the peak shift is about 2% during Raman analysis in ordinary SOS. It can be seen that the potential stress is quite low.

Now that the analysis of the mechanical properties of the Si thin film has been completed, the concentration of defects present in the Si film is analyzed.

Deep Level Transient Spectroscopy (DLTS) is a method of measuring the concentration of defects in Si films. DLTS is a device for measuring the concentration of defects in the thin film, and can measure the concentration of defects with depth.

Defects present in the Si film are mainly traps of electrons. Among them, traps present in the Si film are trapped once electrons are escaped when the activation energy is supplied. At this time, trap D1 having an activation energy of E _C -0.307eV and , The activation energy is E _C -0.522 eV trap D2, where E _C represents the conduction energy (conduction energy) of Si.

Figure 5 is a result of analyzing the sample deposited (as grown) and hydrogenated RTA without any additional process by DLTS. As grown from the surface without any further process (as grown) D2 defects increase and D1 defects decrease from the surface to the lower portion, it can be seen that the D2 defects increase significantly. However, in the sample subjected to RTA after hydrogenation, it can be seen that the defects D1 and D2 decrease significantly from the surface to the bottom.

Now that we have finished analyzing the defect concentration of the Si film, we will now analyze the electrical properties of the Si film. As a method of measuring the electrical properties of a Si film, after fabricating an element in a thin film, the characteristics of voltage and conductance can be measured, or the characteristics of voltage and current can be measured.

The charts measuring the V-C and V-I characteristics of the Si film are shown in Figs. 6A and 6B. It can be seen from FIG. 6a that the conductance is lower when a sample subjected to RTA after hydrogenation has a reverse voltage than a sample having only RTA. This means that the size of the device can be made smaller, and less conductance is advantageous for integration. Because the conductance is C = (ε · d) / A, in order to make the conductance small, the area A must be large or the thickness d must be small, and other materials must have a small dielectric constant ε. . However, if the area is increased, the device becomes large, so that the device can be made very small by reducing the thickness by using a material having a small dielectric constant.

In Fig. 6b, it can be seen that the leakage current is significantly reduced to about 10 ^-10 A when V = 0, which not only reduces power consumption but also reduces noise, resulting in less error in signal processing. It can be seen.

The optical, mechanical, defect concentrations, and electrical properties of the defects in the Si films above were analyzed. When the Si film was further processed, such as RTA or hydrogenation, rather than only Si grown, The quality of the Si film was improved, and the quality of the Si film was significantly improved when the RTA was performed after the hydrogenation rather than the RTA alone. Therefore, when Si is deposited, hydrogenated, and RTA, most of defects existing in Si disappear and crystallinity is improved. Thus, SOI of high quality can be manufactured through this method.

As described above, the present invention reduced the deposition temperature of the Si thin film by using RTCVD, and used hydrogenation and RTA to improve the quality of the deposited Si thin film. Both hydrogenation and RTA have the effect of reducing defects and removing potential stress in the deposited Si thin films, and are more effective when two processes are used together than when one process is performed individually. Through the present invention, it is possible to use a wide range of SOI substrates not commonly used due to defects and potential stresses of Si thin films generated when producing SOI substrates, and applied to more integrated circuits and devices using SOI. Therefore, the development of the electronics industry and the device industry can be made, and the thin film device technology can be applied to the low temperature process and the precise process, and thus the thin film device technology can be developed.

Claims (18)

In the method for manufacturing a thin film device; After the deposition of the thin film, a thin film device manufacturing method, characterized in that a hydrogenation process for reducing the defects and potential stress present in the deposited thin film layer is added. The method of claim 1; The hydrogenation step, While injecting hydrogen gas (H ₂ ) into the reactor, the microwave generator was operated with a pressure of 0.1 to 1 torr and a temperature of 200 to 500 ° C. to excite the injected hydrogen into a plasma state for 10 minutes to The thin film device manufacturing method, characterized in that to remove the defects of the thin film device by reacting for 4 hours. In the method of manufacturing a thin film device; After the deposition of the thin film, a thin film device manufacturing method characterized in that the addition of an oxidation heat treatment process to reduce the defects and potential stress present in the deposited thin film layer. The method of claim 3; The oxidation heat treatment step, A method of manufacturing a thin film device, characterized by removing the defects of the thin film device by rapidly increasing the temperature of the reactor and maintaining oxygen for about one hour while injecting oxygen into the reactor to oxidize the surface of the thin film device. In the method for manufacturing a thin film device; After the deposition of the thin film, a hydrogenation process of injecting hydrogen gas into the reactor and heating it to reduce defects and potential stresses in the deposited thin film layer, and injecting oxygen into the reactor after the hydrogenation process to heat the film while oxidizing the surface of the thin film. Thin film device manufacturing method characterized in that the oxidation heat treatment step is added. The method according to any one of claims 1 to 5; The thin film device is a thin film device manufacturing method characterized in that the SOI. The method according to any one of claims 1 to 5; The thin film device is a thin film device manufacturing method, characterized in that the semiconductor material containing Si or Si. The method according to any one of claims 1 to 5; The thin film device is a thin film device manufacturing method, characterized in that the semiconductor material containing Ge or Ge. The method according to any one of claims 1 to 5; The thin film device is a thin film device manufacturing method characterized in that the SOI. A control unit for controlling the amount and rate of the reaction gas flowing into the furnace (furnace), and a halogen lamp therein so that the light can be sufficiently transmitted to the substrate to be deposited, and the transparent quartz tube to transmit the light of the lamp Rapid photothermal chemical vapor deposition comprising a reactor having a quartz tube, a microwave generator for generating microwaves to heat the furnace, and a vacuum unit for maintaining the reactor in a vacuum state. A method for manufacturing a thin film device using a Rapid photothermal chemical vapor deposition device; After the deposition of the thin film, a thin film device manufacturing method, characterized in that a hydrogenation process for reducing the defects and potential stress present in the deposited thin film layer is added. The method of claim 10; The hydrogenation step, While injecting hydrogen gas (H ₂ ) into the reactor, the microwave generator was operated with a pressure of 0.1 to 1 torr and a temperature of 200 to 500 ° C. to excite the injected hydrogen into a plasma state for 10 minutes to The thin film device manufacturing method, characterized in that to remove the defects of the thin film device by reacting for 4 hours. A control unit for controlling the amount and rate of the reaction gas flowing into the furnace (furnace), a halogen lamp therein so that the light can be sufficiently transmitted to the substrate to be deposited, and the transparent quartz tube to transmit the light of the lamp Rapid photothermal chemical vapor deposition comprising a reactor having a quartz tube, a microwave generator for generating microwaves to heat the furnace, and a vacuum unit for maintaining the reactor in a vacuum state. A method for manufacturing a thin film device using a Rapid photothermal chemical vapor deposition device; After the deposition of the thin film, a thin film device manufacturing method characterized in that the addition of an oxidation heat treatment process to reduce the defects and potential stress present in the deposited thin film layer. The method of claim 12; The oxidation heat treatment step, A method of manufacturing a thin film device, characterized by removing the defects of the thin film device by rapidly increasing the temperature of the reactor and maintaining oxygen for about one hour while injecting oxygen into the reactor to oxidize the surface of the thin film device. A control unit for controlling the amount and rate of the reaction gas flowing into the furnace (furnace), a halogen lamp therein so that the light can be sufficiently transmitted to the substrate to be deposited, and the transparent quartz tube to transmit the light of the lamp Rapid photothermal chemical vapor deposition comprising a reactor having a quartz tube, a microwave generator for generating microwaves to heat the furnace, and a vacuum unit for maintaining the reactor in a vacuum state. A method for manufacturing a thin film device using a Rapid photothermal chemical vapor deposition device; After the deposition of the thin film, a hydrogenation process of injecting hydrogen gas into the reactor and heating it to reduce defects and potential stresses in the deposited thin film layer, and injecting oxygen into the reactor after the hydrogenation process to heat the film while oxidizing the surface of the thin film. Thin film device manufacturing method characterized in that the oxidation heat treatment step is added. The method according to any one of claims 10 to 14; A thin film device manufacturing method comprising using a single crystal sapphire as the substrate to be deposited. The method according to any one of claims 10 to 14; A thin film device comprising any one of Al ₂ O ₃ single crystal and polycrystal, Y ₂ O ₃ single crystal, M ₂ O single crystal, Mullite, AlN single crystal and polycrystal, and glass-ceramic as the substrate to be deposited. Manufacturing method. The method according to any one of claims 10 to 14; The thin film device is a thin film device manufacturing method, characterized in that the silicon material containing silicon or silicon. The method according to any one of claims 10 to 14; The thin film device is a thin film device manufacturing method characterized in that the Ge or a semiconductor material containing Ge.