KR20110011003A - Hot-wire chemical vapor deposition apparatus including electrical field controlling apparatus and method of fabricating thin film using the same - Google Patents

Abstract

PURPOSE: A hotwire chemical vapor deposition device and a thin film manufacturing method thereof are provided to improve the uniformity of a thin film by controlling electric field which is generated from the hotwire during a thin film deposition process. CONSTITUTION: A substrate is installed inside a chamber(110). A first bias voltage apply part(114) applies a first bias voltage to the substrate. A gas supply part supplies reaction gas to the chamber. A hotwire(130) emits heat which dissociates the reaction gas and is arranged within the chamber. A voltage apply part applies a second bias voltage to the hotwire. A control part controls a voltage which is supplied from the first bias voltage apply part and the second bias voltage apply part.

Description

Hot-wire chemical vapor deposition apparatus including electrical field controlling apparatus and method of fabricating thin film using the same}

An apparatus for constantly controlling an electric field around a substrate in a hot ray chemical vapor deposition apparatus, and a method for manufacturing a thin film in a hot ray chemical vapor deposition apparatus using the apparatus.

The silicon thin film can be applied to various devices, and various researches for improving characteristics and improving productivity have been conducted to lower the production cost of the devices. Polycrystalline thin film silicon can be produced by crystallization or direct growth. Crystallization is a method in which a-Si is formed on a substrate and then a-Si is converted to poly-Si by ELA (Eximer laser annealing) or RTA (rapid thermal annealing). However, ELA has a high manufacturing cost, and RTA has a problem that a glass substrate is bent.

Direct growth is a method of growing poly-Si directly on a substrate by thermal CVD, hot-wire CVD (HW-CVD), or very high frequency CVD (VHF-CVD). However, thermal CVD requires high temperature in order to obtain high quality crystals, making it difficult to use glass substrates. HW-CVD or VHF-CVD is difficult to manufacture large-area thin films due to low uniformity of thin films.

An embodiment of the present invention is to improve the uniformity of the thin film by adjusting the electric field generated from the hot-wire (hot-wire) during the thin film deposition in hot-wire chemical vapor deposition (HWCVD), and to increase the growth rate of the thin film It provides a heat ray chemical vapor deposition apparatus to increase.

Another embodiment of the present invention provides a method for manufacturing a thin film using a hot-ray chemical vapor deposition apparatus having the electric field control device.

Hot-wire chemical vapor deposition apparatus having an electric field control device according to an embodiment of the present invention comprises a chamber in which a substrate is mounted;

A first bias voltage applying unit configured to apply a first bias voltage to the substrate;

A gas supply unit supplying a reaction gas to the chamber;

A heating wire disposed in the chamber and dissipating heat to dissociate or to smooth the reaction gas; And

And a second bias voltage applying unit configured to apply a second bias voltage to the hot wire.

The hot wire chemical vapor deposition apparatus according to an embodiment further includes a control unit for controlling the voltage supplied from the first bias voltage applying unit and the second bias voltage applying unit;

The controller controls the first bias voltage applying unit and the second bias voltage applying unit to supply voltages having different signs to the first bias voltage and the second bias voltage.

AC voltages may be applied to the first bias voltage and the second bias voltage, respectively.

According to another embodiment, the heating wire includes a plurality of heating wires, and the plurality of heating wires are arranged in parallel with each other, and the controller controls the current to flow in adjacent directions to the adjacent heating wires.

The positive and negative voltages having different magnitudes may be alternated to the first bias voltage and the second bias voltage, respectively.

According to another aspect of the present invention, there is provided a method of manufacturing a thin film using a thermal ray chemical vapor deposition apparatus comprising: a first step of loading a substrate into a chamber;

A second step of raising the temperature of the hot wire to the dissociation temperature of the introduced reaction gas;

Supplying a reaction gas for forming silicon into the chamber; And

And supplying a first bias voltage to the substrate and supplying a second bias voltage to the heating wire.

Hot-wire chemical vapor deposition apparatus having an electric field control device according to an embodiment of the present invention is able to produce a uniform thin film on the substrate by adjusting the electric field on the substrate, and by applying a bias voltage to the substrate and the hot wire, respectively The film deposition rate can be controlled and the crystal size of the film can be controlled.

Hereinafter, with reference to the accompanying drawings will be described in detail a hot-wire chemical vapor deposition apparatus having a field control device according to an embodiment of the present invention and a thin film manufacturing method using the same.

1 is a view schematically showing a hot-ray chemical vapor deposition apparatus having an electric field control device according to an embodiment of the present invention.

Referring to FIG. 1, a thermal ray chemical vapor deposition apparatus 100 may supply a reaction gas into a chamber 110 in which a substrate S is loaded, a substrate holder 112 holding a substrate S, and a chamber 110. The reaction gas supply device 120 and a hot-wire 130 dissociating the reaction gas flowing into the chamber 110 to form charged nanoparticles.

Electrode pads 132 are connected to both ends of the heating wire 130, respectively. A predetermined voltage is applied to the electrode pad 132 from the voltage source 134, and thus heat is emitted from the heating wire 130.

The substrate holder 112 is formed of a conductor, and a first bias voltage applying unit 114 for applying a first bias voltage is connected to the substrate holder 112. By the first bias voltage, charged particles of a specific polarity are easily deposited on the substrate S.

The second bias voltage applying unit 136 for applying the second bias voltage is connected to the hot wire 130.

The chamber 110 is in communication with the vacuum exhaust machine (V), and although not shown, may include a substrate entrance for loading and unloading the substrate (S).

The reaction gas supply device 120 supplies the reaction gas to the chamber 110. The reaction gas supply device 120 includes a shower head 122. The reaction gas is supplied to the chamber 110 through the inlet 124.

The hot wire 130 is disposed between the shower head 122 and the substrate (S). The hot wire 130 may include a metal such as tungsten (W). The heating wire 130 generates heat by electric resistance when a current is applied. The heat generated from the hot wire 130 chemically dissociates the reaction gas supplied from the shower head 122. The hot wire 130 may be adjusted to generate enough heat to dissociate the bonds between the elements in the reaction gas. According to an embodiment, when the reaction gas includes elements of a thin film substantially formed on the substrate S, the heating wire 130 may dissociate the reaction gas to form charged nanoparticles. A second bias voltage is applied to the heating wire 130 to control the charged nanoparticles made by the heating wire 130.

When producing a silicon thin film, the reaction gas may include a gas mainly composed of a silane-based compound represented by Si _n H _{2n + 2} (where n is a natural number). For example, the reaction gas may include monosilane, disilane, trisilane, tetrasilane, or the like. According to another embodiment, the reaction gas is fluorinated silane represented by Si _n H _{2n + 2-m} F _m (where n and m are natural numbers m <2n + 2 and m may also include 0), for _{example, SiH3F, SiH 2 F 2,} SiHF 3, SiF 4, Si 2 F 6, Si 2 HF 5, Si 3 F 8; Organosilanes represented by Si _n R _{2n + 2-m} H _m , for example Si (CH ₃ ) H ₃ , Si (CH ₃ ) ₂ H ₂ , Si (CH ₃ ) ₃ H, or the like, Mixtures may be included.

The reaction gas may be provided into the chamber 110 in a gaseous state or in the form of vaporized vaporized liquid source. When the reaction gas is provided in the form of vaporized vapor of the liquid source, a carrier gas that carries the vapor into the chamber 110 may additionally be used. Examples of the carrier gas may be a non-reactive gas such as hydrogen, nitrogen, helium, argon, or the like.

Reference number d refers to the separation distance between the hot wire 130 and the substrate (S).

2 is a schematic diagram showing an electric field distribution by the heating wire 130 when an 18V DC voltage is applied to both ends of the heating wire 130. Referring to FIG. 2, it can be seen that an electric field is generated around the heating wire 130 as a voltage is applied to the heating wire 130. In FIG. 2, the gray scale and the arrow length indicate the magnitude of the electric field. In FIG. 2, current flows from the left side (inlet) to the right side (outlet), and the electric field of the inlet is much larger than the electric field of the outlet. A large positive electric field is formed at the inlet, attracting negatively charged particles, and rejecting positively charged particles. The electric field distribution causes the distribution of the positive and negative charges to vary according to the position of the hot wire and the distance to the hot wire, making it difficult to uniformly form the thin film in the manufacture of the large-area thin film in the hot wire chemical vapor deposition apparatus.

FIG. 3 is a graph illustrating a result of measuring currents at the inlet and outlet of the heating wire 130 when the second bias voltage is applied at −25 V to 25 V in the voltage applying device 100 of FIG. 1. In the experiment, 4 helically-wounded thorium-doped tungsten wires wound by four spirals of the heating wire 130 were used, and the length thereof was 13 cm and the diameter was 0.5 mm. The heating wire 130 was heated to be maintained at 2000 ° C. with a 18 V voltage supplied by a DC power supply. 30% SiH ₄ -70% H ₂ gas was supplied to the chamber 110 at a flow rate of 50 standard cubic centimeter per minute (sccm). The working and initial pressures were 66.7 Pa and 9.3x10 ^-4 Pa, respectively. In order to measure the current in the chamber 110, a 3 cm x 3 cm square iron plate is placed 4.5 cm below the heating wire 130 in the direction of the substrate S, respectively, in the inlet and outlet portions of the heating wire 130 in the current flow direction. It was. The chamber 110 is cylindrical in shape 20 cm in diameter by 15.5 cm in height. Si thin films were deposited on Si (001) wafers.

Referring to FIG. 3, the current value measured under the input has a positive value relatively to the current value measured under the output regardless of the second bias voltage. Therefore, the inlet attracts negatively charged particles and rejects positively charged particles.

Therefore, in order to form a homogeneous polycrystalline thin film on the substrate, it is important to form a uniform electric field from the hot wire onto the substrate.

4 is a plan view illustrating an arrangement of hot wires according to an exemplary embodiment. Referring to FIG. 4, the plurality of hot wires 231 to 235 spaced apart from the substrate S of FIG. 1 are disposed in parallel to each other. The first heating wire 231, the third heating wire 233, and the fifth heating wire 235 are connected at both ends to the first voltage source 240 to supply the first voltage, and the second heating wire 232 and the fourth heating wire 235. Both ends of 234 are connected to the second voltage source 250 to receive the second voltage. The controller 260 controls the first voltage source 240 and the second voltage source 250 so that the first voltage and the second voltage have different polarities. Accordingly, the electric field from the hot wires 231-235 becomes more uniform with respect to the substrate, and thus the electric field applied to the thin film by the hot wires 231-235 may be constant.

In FIG. 4, five hot wires are exemplarily disclosed, but embodiments of the present invention are not limited thereto. A plurality of hot wires may be formed, and the current directions in neighboring hot wires may be supplied differently.

Referring back to FIG. 1, a first bias voltage is applied to the substrate holder 112, and the first bias voltage is applied to have a sign different from that of the second bias voltage. That is, according to the second bias voltage, the polarity of the charge particles spaced apart from the heating wire 130 may be controlled. For example, when a positive bias voltage is applied to the heating wire 130, more negatively charged particles gather around the heating wire 130, and the positively charged particles move away from the heating wire 130. At this time, if the first bias voltage is a negative bias voltage different from the second bias voltage, since the positively charged particles pushed away from the hot wire 130 are more easily deposited on the substrate S, the deposition rate of the thin film may be increased.

On the contrary, when a negative bias voltage is applied to the heating wire 130, more positively charged particles gather around the heating wire 130, and the negatively charged particles are separated from the heating wire 130. At this time, if the first bias voltage is a positive bias voltage different from the second bias voltage, since the negative charge particles pushed out from the hot wire 130 are more easily deposited on the substrate S, the deposition rate of the thin film may be increased.

Meanwhile, since not only negatively charged particles but also positively charged particles are used for thin film deposition, the control unit 260 may control the first bias voltage applying unit 114 and the first bias voltage so that the first bias voltage and the second bias voltage have different polarities at predetermined periods. When the 2 bias voltage applying unit 136 is adjusted, since the positive and negatively charged particles are deposited on the substrate S at a predetermined cycle, the deposition rate may be increased. In addition, a glass substrate can be used to deposit a silicon thin film even at low temperatures.

On the other hand, when the alternating current is used as the first bias voltage and the second bias voltage, the magnitudes of the positive voltage and the negative voltage may not be the same. Such asymmetrical voltage application can promote the balance of the electric field from the heating wire by making the magnitude of the positive voltage larger than the magnitude of the negative voltage when the negatively charged particles prevail in the chamber, which can help to uniform the thin film.

FIG. 5 is a flowchart showing a manufacturing step of a method of manufacturing a crystalline silicon thin film (hereinafter, the method of the present invention) using the above-described hot-wire chemical vapor deposition apparatus according to another embodiment of the present invention.

The substrate S is mounted on the substrate holder 112 to charge the substrate S into the chamber 110 (first step). In this case, the pressure of the chamber 110 may be maintained at several tens of mtorr, for example, about 10 ⁻² torr. The substrate S may be a glass substrate. Thereafter, hydrogen gas (H ₂ ) may be injected into the chamber 110 as an atmosphere gas for preventing the heating wire 130 from being oxidized. The substrate S and the heating wire 130 may be maintained at a predetermined distance suitable for forming a crystalline silicon film or crystalline silicon nanoparticles on the substrate S, for example, between the substrate S and the heating wire 130. The distance can be about 6.5 cm. When other conditions are constant, the crystalline silicon film may be formed on the substrate S by adjusting the distance between the substrate S and the hot wire 130.

Next, the temperature of the heating wire 130 is increased to be able to dissociate the reaction gas to be injected (second step). For example, when the reaction gas for forming silicon flows in, the heating wire 130 may be increased to 1400 ° C-2000 ° C, preferably 1600 ° C-1800 ° C.

Next, the reaction gas is supplied to the chamber 110 through the gas inlet 124 (third step). The reaction gas may be silane. The substrate 40 may be maintained at 300 ° C-700 ° C. The pressure of the chamber 110 may be 1 torr or less. In this case, the reaction gas may be 30% silane gas and 70% hydrogen gas.

The introduced reaction gas is dissociated while passing through the hot wire 130. Dissociated reaction gas becomes charged crystalline nanoparticles. That is, it may be present as positively charged nanoparticles, negatively charged nanoparticles, and neutral nanoparticles.

The first bias voltage is applied to the heating wire 130 and the second bias voltage is applied to the substrate holder 112 (fourth step). The first bias voltage and the second bias voltage are controlled to have different polarities.

In addition, the first bias voltage and the second bias voltage may use a DC voltage or apply an AC voltage, and when the AC voltage is applied, voltages having different phases from each other may be applied. The period of the AC voltage may be 0.01 Hz to 10 kHz.

Meanwhile, when the first bias voltage is an AC voltage, the positive and negative voltages may have different magnitudes. In the case of the second bias voltage, the magnitude of the positive voltage and the negative voltage may be different from each other.

When the heating wire is composed of a plurality of heating wires (131-135) as shown in Figure 4, the current flows in different directions to the alternating heating wires (131-135) so that the magnitude of the electric field formed from the heating wire It can be made uniform.

When the thin film deposition method according to the embodiment of the present invention is used, the thin film is easily deposited and the size of the charged nanoparticles can be controlled, so that the pressure in the chamber is increased to several torr so as not to impair the characteristics of the thin film. Therefore, the growth rate of the thin film can be improved.

The crystalline semiconductor thin film may be manufactured in the same manner as described above to manufacture a solar cell, a display display device, and a TFT device.

While the invention has been shown and described with reference to certain embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the invention as defined by the appended claims. Therefore, the true scope of protection of the present invention should be defined only by the appended claims.

1 is a view schematically showing a hot-ray chemical vapor deposition apparatus having an electric field control device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing an electric field distribution by a hot wire when an 18 V DC voltage is applied to both ends of the hot wire of FIG. 1.

FIG. 3 is a graph illustrating a result of measuring currents at an input part and an outlet part of the heating wire when the second bias voltage is applied at −25 V to 25 V in the voltage applying device of FIG. 1.

Figure 4 is a plan view showing the arrangement of the hot wire according to an embodiment of the present invention.

5 is a flowchart showing a method of manufacturing a crystalline silicon thin film using the above-described hot-wire chemical vapor deposition apparatus according to another embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

100: hot wire CVD apparatus 110: chamber

112: substrate holder 114: first bias voltage applying unit

120: reaction gas supply 122: shower head

124: inlet 130: hot wire

134: voltage source 136: second bias voltage applying unit

Claims (12)

A chamber in which a substrate is mounted; A first bias voltage applying unit configured to apply a first bias voltage to the substrate; A gas supply unit supplying a reaction gas to the chamber; A heating wire disposed in the chamber and dissipating heat dissociating the reaction gas; And And a second bias voltage applying unit configured to apply a second bias voltage to the hot wire. The method of claim 1, And a controller configured to control a voltage supplied from the first bias voltage applying unit and the second bias voltage applying unit. The control unit is a hot wire chemical vapor deposition apparatus for supplying a voltage having a different sign to the first bias voltage and the second bias voltage. The method of claim 2, The hot wire has a plurality of hot wires, the plurality of hot wires are arranged in parallel with each other, the control unit is a hot wire chemical vapor deposition apparatus for controlling the current flow in the adjacent hot wires in different directions. The method of claim 2, And an alternating current voltage is applied to the first bias voltage and the second bias voltage, respectively. The method of claim 4, wherein Hot-wire chemical vapor deposition apparatus is applied to the first bias voltage and the second bias voltage alternately applied positive and negative voltages of different magnitudes, respectively. In the thin film manufacturing method using the heat ray chemical vapor deposition apparatus of claim 1, Loading a substrate into the chamber; A second step of raising the temperature of the hot wire to the dissociation temperature of the introduced reaction gas; Supplying a reaction gas for forming silicon into the chamber; And And supplying a first bias voltage to the substrate and supplying a second bias voltage to the heating wire. The method of claim 6, The method of claim 1, wherein the first bias voltage and the second bias voltage have different polarities. The method of claim 7, wherein And the first bias voltage and the second bias voltage are alternating voltages, respectively. The method of claim 7, wherein The first bias voltage and the second bias voltage is a thin film manufacturing method in which the positive and negative voltages of different sizes are alternately changed. The method of claim 7, wherein The heating wire is provided with a plurality of heating wire, the heating wire is a thin film manufacturing method in which voltage is applied to both ends of the heating wire so that the current direction of the heating wire alternately arranged. The method of claim 6, The first bias voltage and the second bias voltage is a thin film manufacturing method for controlling the deposition rate, uniformity and particle size of the semiconductor thin film by selectively controlling the size and current direction respectively. The method of claim 6, A method of manufacturing a solar cell, a display display device, a TFT device by crystallizing a semiconductor thin film by the above method, and a related device.

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