KR20100042150A - Low temperature polysilicon deposition apparatus - Google Patents

Abstract

PURPOSE: A low temperature polysilicon deposition device is provided to improve a deposition speed and a crystal property by dissolving or ionizing material gas by applying a bias to a substrate. CONSTITUTION: A gas supply unit(20) timeshares and injects material gas and auxiliary gas to a chamber for depositing a low temperature polycrystalline silicon. A substrate unit is installed inside a chamber and includes a substrate tool and a heater. The heater heats the substrate with the temperature for depositing the low temperature polycrystalline silicon. An energy supply unit(40) applies a bias to the substrate tool by processing the injected material gas with plasma. An exhaust unit(50) is connected to the chamber and exhausts the chamber.

Description

Low temperature polysilicon deposition apparatus

The present invention relates to a low temperature polysilicon deposition apparatus, and more particularly, to a low temperature polysilicon deposition apparatus for depositing low temperature polysilicon uniformly and reproducibly while shortening the process time.

In the flat panel display (FPD) market, the share of thin film transistor liquid crystal display (TFT-LCD) is rapidly growing. However, since LCD technology has a limitation inherent in self-luminous, research on OLED (Organic Light Emitting Diode) displays has been actively conducted in recent years.

An OLED display may be classified into a passive matrix type OLED and an active matrix type OLED (AMOLED). The active matrix type AMEL is much more advantageous than the passive matrix type LED in terms of power consumption reduction, stability improvement, and large area due to low voltage driving. In order to manufacture such an active matrix type AMOLED, it is necessary to manufacture semiconductor devices, TFTs and arrays, which are polycrystalline silicon, particularly in terms of current supply capability and stability. Advantageous research on low temperature polysilicon is being actively conducted.

In addition, the importance of low temperature polysilicon film is increasing in the photovoltaic technology. This is one of the most promising alternative energy technologies with no pollution and no limit in solar power technology, and it can combine the excellent properties of crystalline silicon (c-Si) and the advantages of mass production process of amorphous silicon in polycrystalline silicon solar cells. Because there is.

As a method of forming such low-temperature polycrystalline silicon, there is a laser technique in which an amorphous silicon film is grown on a glass substrate, and then the amorphous silicon film is crystallized using a laser. Laser techniques can be divided into Excimer Laser Anneal (ELA), which uses an excimer laser as a gas laser, and Sequential Lateral Solidification (SLS), which induces horizontal crystal growth. have.

In order to implement such a technique, a laser apparatus related technology is disclosed in US Pat. No. 5879803, US Pat. No. 7071709, US Pat. 5840118, US Pat. No. 6535554, and the like. Most of the laser equipment related technology is to solve the root problem caused by the explosive instant reaction between the laser beam and the silicon (si). However, since these techniques have a problem of low inter-pulse stability of the gas laser method, particularly excimer laser annealing (ELA), to solve this problem, the Diode Pumped Solid State (DPSS) technology using a solid laser. Research is ongoing.

On the other hand, in order to solve the problems caused by the explosive instant reaction between the laser beam and silicon of the laser technique, there is a non-laser technique using a solid phase crystallization method, metal induced crystallization method, metal induced side crystallization method. The solid phase crystallization method is a technique of crystallizing by heat treatment of amorphous silicon on a glass substrate, which may cause deformation of the glass substrate due to heat shock and rapid temperature gradient on the glass substrate. In order to solve this problem, metal induced crystallization (MIC) method that induces crystallization at low temperature by applying various metal catalysts such as nickel (Ni), copper (Cu), aluminum (Al), palladium (Pd) on amorphous silicon This has been proposed.

However, the metal induced crystallization (MIC) method may exhibit an increase in leakage current due to metal contamination because a substantial amount of metal diffuses into the active region of the TFT. This increase in leakage current due to metal contamination can be suppressed by a metal induced side crystallization (MILC) method in which metal is deposited in the source and drain regions and then seeded to grow the metal toward the gate region. Can be. However, there is still a factor of increasing leakage current since metals growing in the source region and the drain region, respectively, cause metal contamination by encountering each other in the middle of the gate region. In order to solve this problem, a metal induction crystallization method (MICC) using a cover layer has been proposed.

In order to realize these non-laser technologies, non-laser equipment related technologies are proposed in US Pat. No. 6,632,212, US Pat. No. 6,616, US Pat.

All of the above described low temperature polysilicon deposition methods are methods of first depositing amorphous silicon on a substrate and then converting it to polycrystalline silicon. This method is a relatively expensive and expensive method in addition to the above technical limitations because it has to go through a two-step process. Therefore, the most efficient method is the direct deposition method of depositing polycrystalline silicon on a substrate in one process.

As a method of directly depositing polysilicon on a substrate, Chemical Vapor Deposition (CVD) is used.Plasma Enhanced Chemical Vapor Deposition (PECVD) and HOT Wire Chemical Vapor Deposition: HWCVD), Micro-Wave Chemical Vapor Deposition (MWCVD), etc. are also being studied.

In the chemical vapor deposition (CVD) method, silane (SiH ₄ ) and hydrogen (H ₂ ) are mainly used as source gases. By decomposing these into hydrogen radicals such as H, Si, SiH, etc. by their respective energy sources, some of them form silicon (Si) on the substrate, and others form secondary or more hydrogen radicals. Thereby forming silicon (Si). At this time, by adjusting the hydrogen mixing ratio (or concentration of silane (SiH ₄ )) of the silane (SiH ₄ ) and hydrogen (H ₂ ) gas to enable the phase transition from amorphous silicon to polysilicon, low-temperature polycrystalline silicon can be formed. have. This can be described as an 'etching model' in which hydrogen atoms act as etchant to form a stable silicon structure by forming a chemical equilibrium state between deposition and etching at the deposition surface.

In order to apply low-temperature polycrystalline silicon to the industrialization of active matrix type OLED (AMOLED), solar cell (Photo-voltaic (PV)), etc., the deposition rate must be high. The deposition rate of should be secured. In the above-described chemical vapor deposition (CVD) method, as the concentration of silane (SiH ₄ ) increases, the deposition rate of low-temperature polycrystalline silicon increases, but the crystallinity of the deposited polycrystalline silicon is lowered, resulting in phase transition to amorphous silicon. This can be explained by the 'etching model', because increasing the flow rate of the silane (SiH ₄ ) increases the deposition rate but the deposition rate is faster than the crystallization rate, and thus the deposition film is not sufficiently crystallized.

In order to solve this problem, the xylene is possible to exhibit an improved determination of properties on the same level of absolute by reducing the flow rate of xylene (SiH ₄₎ of (SiH ₄₎ to increase or xylene (SiH ₄₎ the temperature of the. To this end, in the conventional direct deposition method of plasma CVD (Plasma CVD) has to increase the substrate temperature or increase the power, in HWCVD (HWCVD) there is a problem to increase the temperature of the hot wire.

Accordingly, an object of the present invention is to provide a low-temperature polycrystalline silicon deposition apparatus that obtains improved crystal characteristics while improving the deposition rate.

Another object of the present invention is to provide a low-temperature polysilicon deposition apparatus that achieves improved crystal characteristics while shortening processing time.

Another object of the present invention is to provide a low-temperature polysilicon deposition apparatus to lower the manufacturing cost.

Low temperature polysilicon deposition apparatus according to the present invention for achieving the above object, the chamber portion having a chamber for securing the reaction space of the chemical vapor deposition process; A gas supply unit for time-dividing and injecting a source gas and an auxiliary gas for depositing low-temperature polycrystalline silicon into the chamber; A substrate portion provided in the chamber and having a substrate fixture for supporting a substrate, and a heater portion for heating the substrate to a temperature for depositing the low temperature polycrystalline silicon; An energy supply unit configured to directly apply a bias to the substrate fixture to convert the injected source gas into a plasma to deposit the low temperature polycrystalline silicon; And it is in communication with the chamber, characterized in that it comprises an exhaust for exhausting the chamber.

Preferably, in order to stably apply the bias to the substrate jig, an insulating member insulating the substrate jig and the heater may be provided between the substrate jig and the heater.

Preferably, a protective member for protecting the heater unit from damage caused by plasma generated in the chamber may be provided on the side portion of the heater unit.

Preferably, as the heater unit, it is possible to use any one of a hot wire heater unit and a lamp heater unit.

Preferably, as the source gas, not only silane (SiH ₄ ) and hydrogen (H ₂ ) but also a gas capable of being decomposed or ionized in the form of hydrogen radicals containing silicon atoms by hydrogen plasma may be used.

Preferably, the source gas and the auxiliary gas of the gas supply unit may be time-divided and supplied to the gas inlet and the exhaust port of the chamber.

Preferably, as the auxiliary gas, it is possible to use argon (Ar) gas which increases dissociation of hydrogen and hydrogen radicals.

According to the present invention, a bias is applied to a substrate in a vacuum chamber to decompose or ionize an applied source gas through a time-division gas supply device, thereby attracting hydrogen radicals to the substrate and depositing low-temperature polycrystalline silicon on the substrate. Can be deposited uniformly and reproducibly.

Hereinafter, a low temperature polysilicon deposition apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

 1 is a schematic configuration diagram of a low-temperature polycrystalline silicon vapor deposition apparatus according to the present invention. Referring to FIG. 1, the low temperature polysilicon deposition apparatus 100 according to the present invention is a substrate bias type low temperature polycrystalline silicon deposition apparatus, which includes a chamber portion 10, a gas supply portion 20, a substrate portion 30, and energy. The supply part 40 and the exhaust part 50 are comprised.

Here, the chamber part 10 has a chamber 11 for securing a high vacuum internal reaction space in order to coat the coating material by chemical vapor deposition such as PECVD. Outside the chamber 11, a pressure gauge 13 for measuring the internal pressure of the chamber 11 is generally provided. The reaction pressure in the chamber 11 is preferably a reaction pressure suitable for low temperature polycrystalline silicon deposition, for example, 10 ⁻⁴ Torr to 10 ⁻¹ Torr.

The gas supply unit 20 is a part for supplying source gas and auxiliary gas for low-temperature polycrystalline silicon deposition, and includes first, second, and third gas flow control devices 21a, 21b, 21c, and first, second, and third sources. Gas valves 23a, 23b, 23c, 1, 2, 3 main gas valves 25a, 25b, 25c, 1, 2, 3 bypass gas valves 27a, 27b, 27c, and gas inlets 29 It is configured to include). The first, second and third gas flow rate control devices 21a, 21b and 21c control the flow rates of the source gas and the auxiliary gas supplied through the respective gas supply pipes.

Each of the first, second, and third gas valves 23a, 23b, and 23c is provided in a gas supply pipe in front of the first, second, and third gas flow control devices 21a, 21b, and 21c, and opens and closes the gas supply pipe. The source gas and the auxiliary gas are allowed to flow or not flow to the first, second and third gas flow control devices 21a, 21b and 21c through the supply pipe.

Each of the first, second and third main gas valves 25a, 25b and 25c is installed in the main gas supply pipe P1 at the rear end of the first, second and third gas flow control devices 21a, 21b and 21c. By opening / closing the gas supply pipe P1, the supply gas and the auxiliary gas may not be supplied or supplied to the gas inlet 29 through the main gas supply pipe P1.

Each of the first, second and third bypass gas valves 27a, 27b and 27c is provided in the bypass gas supply pipe P2 at the rear end of the first, second and third gas flow control devices 21a, 21b and 21c. By opening and closing the bypass gas supply pipe P2, the raw material gas and the auxiliary gas are prevented from flowing or flowing to the gas exhaust port A side of the chamber 11 through the bypass gas supply pipe P2.

On the other hand, in order to deposit low-temperature polycrystalline silicon by a chemical vapor deposition method, a source gas, for example, silane (SiH ₄ ), hydrogen (H ₂ ) is mainly used, and auxiliary gas, for example, hydrogen and hydrogen radicals (hydrogen) Argon (Ar) gas is used to increase the dissociation of radicals.

In one of the silicon deposition models, the 'etching model', hydrogen atoms act as an etchant during the silicon deposition process, eliminating an energy unstable array of films, and only the lowest energy array withstanding the etching in an amorphous state. It is an important factor in the deposition of polycrystalline silicon by almost removing the film of the array of. For this purpose, in fact, xylene (SiH ₄₎ and hydrogen vapor deposition step and, xylene (SiH _4), except for the gas, and hydrogen (H ₂₎ for injecting a gas mixture into the chamber of (H ₂₎ in the deposition process of the low-temperature poly-Si Alternately, the processes of the removing step of injecting only gas into the chamber are alternately performed.

Time division gas supply disclosed in Patent Application No. 2001-89339 (Patent No .: 10-419033) filed by the applicant of the present invention on December 24, 2001 (name of the invention: dry etching apparatus and method by high density plasma). By applying the apparatus to the gas supply unit 20 for injecting the raw material gas for forming the polycrystalline silicon of the present invention into the chamber, the silane (SiH ₄ ) gas is directly supplied to the chamber 11 without a flow rate delay, thereby The deposition step and the etching step can be repeated without changing the pressure, thus reducing the overall process time.

Therefore, the time-division gas supply time for improving the characteristics of the polysilicon deposition film by improving the characteristics of the polycrystalline silicon deposition film by rapidly and repeatedly injecting into the plasma reactor without mixing one or more different process gases with different configuration of the supply device for supplying different process gases selectively It is characterized by shortening.

The operation principle of the 'time division gas supply device' applied to the present invention will be described in more detail with reference to FIG.

First, in the first step, the first process gas (231a) is opened, the first main gas valve 251a is opened, and the first bypass gas valve 271a is closed. When Gas1 is injected into the chamber 11 through the main gas supply pipe P11, the first process gas Gas1 dissociates into radicals, ions, electrons, and the like to form a plasma. After reacting with the substrate (not shown) on the part 30, the gas is exhausted to the outside through the gas exhaust port A of the chamber 11, and at the same time, the second gas valve 231b is opened, and the second main gas valve ( The second process gas while the first process gas Gas1 is injected into the chamber 11 through the main gas supply pipe P11 while the 251b is closed and the second bypass gas valve 271b is opened. Gas2 is exhausted by the exhaust pump (not shown) to the gas exhaust port A of the chamber 11 through the bypass gas supply pipe P12 without being injected into the chamber 11.

Subsequently, in the second step, in the state where the second gas valve 231b is opened, the second main gas valve 251b is opened, and the second bypass gas valve 271b is closed, the second process gas ( When Gas2 is injected into the chamber 11 through the main gas supply pipe P11, it is dissociated with radicals, ions, electrons, or the like to form a plasma to react with a substrate (not shown) on the substrate portion 30, and then the chamber 11. Is exhausted to the outside via the gas exhaust port (A) of), and at the same time, the first gas valve 231a is opened, the first main gas valve 251a is closed, and the first bypass gas valve 271a is opened. In this state, while the second process gas (Gas2) is injected into the chamber 11 through the main gas supply pipe (P11), the first process gas (Gas1) by the exhaust pump (not shown), the chamber 11 The gas is exhausted to the gas exhaust port A of the chamber 11 through the bypass gas supply pipe P12 without being injected into the chamber 11.

Therefore, by repeating the first and second process steps sequentially, the operation principle of the time-division gas supply device, characterized in that rapid alternating gas supply is possible, is applied to the gas supply unit 20 of the present invention to shorten the process time. As a result, low-temperature polycrystalline silicon can be deposited at low cost.

In addition, as shown in the enlarged view of FIG. 3, the substrate unit 30 may include a substrate fixture 31, a power supply line 33, a heater unit 35, an insulating member 37, and a protective member ( 39).

Here, the substrate jig 31 is mounted with a substrate (shown in dashed lines) for depositing low-temperature polycrystalline silicon.

The power supply line 33 transmits the bias of the power supply unit 40 to the substrate fixture 31 by being electrically connected to the substrate fixture 31 itself rather than electrically connected to the substrate itself in order to apply a stable bias to the substrate. . Since the internal state of the chamber 11 is a vacuum state and the external state of the chamber 11 is an atmospheric pressure state, the power supply line 33 in the chamber 11 is a connector provided through a wall of the chamber 11, eg, For example, it is electrically connected to the power supply 40 outside the chamber 11 via a feed-through 34. On the other hand, for convenience, although the power supply line 33 is shown as exposed in the interior space of the chamber 11, in order to prevent damage by plasma in the chamber 11, for example, properly in the heater unit 35 Of course, it must be installed.

The heater unit 35 has a plate body 35b provided therein with a heat wire 35a for supplying heat energy to the substrate fixture 31 to heat the substrate to an arbitrary temperature, and further, the heat energy of the heat wire 35a. It has a thermocouple (not shown) to make it constant. Of course, instead of the heat heater 35 shown in the drawing, a lamp heater (not shown) using light energy such as a halogen lamp is also possible.

The insulating member 37 is a member provided between the substrate fixture 31 and the heater portion 35 to apply a stable bias to the substrate, and electrically insulates the substrate fixture 31 from the heater portion 35. As the insulating member 37, for example, a spacer, preferably a ceramic spacer, may be used.

The protection member 39 is provided in the side part of the heater part 35, and protects the side part and lower surface part of the plate body 35b of the heater part 35 from the damage by the plasma in the chamber 11.

On the other hand, as the source gas applied in the hydrogen plasma, Si, SiH, SiH containing not only silane (SiH ₄ ) and hydrogen (H ₂ ) but also silicon (Si) atoms together with ions due to decomposition or ionization by collision with electrons in the plasma. Any gas generating hydrogen radicals such as ₂ , SiH _3, etc. may be used. The present invention, unlike the prior art, supplies energy to decompose or excite silane (SiH ₄ ) and hydrogen (H ₂ ) to a substrate (not shown). At this time, by the DC self-bias generated in the substrate, the generated hydrogen radicals are attracted to the substrate and conversely, the hydrogen ions are separated from the substrate. By appropriately adjusting the DC self-bias according to the structure of the substrate power supply and the electrode, hydrogen radicals can be directionally accelerated and attracted to the substrate, resulting in improved crystallinity. Therefore, low-temperature polycrystalline silicon can be deposited uniformly and reproducibly.

The energy supply unit 40 includes a power supply unit 41 and a matching unit 42. The power supply unit 41 can use MF (-kHz), VHF (60 MHz, 100 MHz), UHF (500 MHz), RF (13.56 MHz), and microwave band frequency (2.54 GHz). The matching section 42 applies the maximum power from the power supply section 40 to the substrate by matching the load impedance of the substrate with the source impedance of the power supply section 40.

The exhaust unit 50 includes a vacuum pump 51, an exhaust pipe 52, an exhaust valve 53, and the like, and communicates with the gas exhaust port A of the chamber 11. The exhaust part 50 exhausts the chamber 11 in order to exhaust the reaction gas in the chamber 11 by the vacuum pump 51 and to adjust the reaction pressure of the chamber 11. At this time, it is also possible to use a booster pump (not shown) for rapid exhaust of the chamber 11.

Therefore, the low temperature polysilicon deposition apparatus having such a configuration applies the bias to the substrate fixture without directly applying the bias to the substrate, and also supplies the raw material gas and the auxiliary gas to the chamber by using a time division gas supply device. Can be deposited uniformly and reproducibly at low cost.

1 is a schematic configuration diagram of a low-temperature polycrystalline silicon vapor deposition apparatus according to the present invention.

2 is a schematic block diagram showing an example of a time division gas supply device applied to a low temperature polycrystalline silicon deposition device according to the present invention.

Fig. 3 is an enlarged view showing the substrate portion of the low temperature polysilicon deposition apparatus according to the present invention.

Claims (7)

A chamber unit having a chamber for securing a reaction space of a chemical vapor deposition process; A gas supply unit for time-dividing and injecting a source gas and an auxiliary gas for depositing low-temperature polycrystalline silicon into the chamber; A substrate portion provided in the chamber and having a substrate fixture for supporting a substrate, and a heater portion for heating the substrate to a temperature for depositing the low temperature polycrystalline silicon; An energy supply unit configured to directly apply a bias to the substrate fixture to convert the injected source gas into a plasma to deposit the low temperature polycrystalline silicon; And  Low temperature polysilicon deposition apparatus communicating with the chamber, comprising an exhaust unit for exhausting the chamber. The low temperature polysilicon deposition apparatus according to claim 1, wherein an insulating member for insulating the substrate jig and the heater is provided between the substrate jig and the heater to stably apply the bias to the substrate jig. . The low temperature polysilicon deposition apparatus according to claim 1, wherein a protection member for protecting the heater unit from damage by plasma generated in the chamber is provided at a side surface of the heater unit. The low temperature polysilicon deposition apparatus according to claim 1, wherein any one of a hot wire heater and a lamp heater is used as the heater. The method of claim 1, wherein as the source gas, not only silane (SiH ₄ ) and hydrogen (H ₂ ) but also a gas capable of decomposing or ionizing in the form of hydrogen radicals containing silicon atoms by hydrogen plasma is used. Low temperature polycrystalline silicon deposition apparatus, characterized in that. The low temperature polysilicon deposition apparatus according to claim 1, wherein the source gas and the auxiliary gas of the gas supply unit are time-divided and supplied to the gas inlet and the exhaust port of the chamber. The low temperature polysilicon deposition apparatus according to claim 1, wherein argon (Ar) gas for increasing dissociation of hydrogen and hydrogen radicals is used as the auxiliary gas.

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