JP2006060130A - Thin film crystallization method and apparatus - Google Patents

Abstract

A thin film crystallization apparatus capable of crystallizing an amorphous thin film in a short time with a simple configuration is provided.
A thin film crystallization apparatus for recrystallizing an amorphous thin film after melting it, a thin tube made of an insulator, a plasma generation gas supply means for introducing a plasma generation gas into one end of the thin tube, and a thin tube The surrounding coil 33, the high frequency power supply 31 that supplies high frequency power to the coil 33, the opposing position of the other end of the thin tube 34 and the amorphous thin film 51, and the distance between the other end of the thin tube 34 and the amorphous thin film 51 A moving means for changing a is provided to irradiate an amorphous thin film 51 disposed in the atmosphere with a microplasma jet 40 generated at the other end of the thin tube 34. While having a simple configuration, the amorphous thin film can be melted in a short time.
[Selection] Figure 1

Description

  The present invention relates to a method for crystallizing an amorphous thin film such as silicon (Si) and an apparatus for carrying out the method, and in particular, it enables polycrystallization in a short time with a simple apparatus.

In recent years, polycrystalline silicon thin films have been used for thin film transistor (TFT) channel layers, solar cell substrates, and the like.
This polycrystalline silicon thin film is formed by forming a silicon amorphous thin film on a glass substrate or SiO ₂ film and crystallizing it by irradiating it with a laser (laser annealing), as described in Patent Document 1 below. It is mainly generated by.

FIG. 5 shows a laser annealing apparatus described in Patent Document 1 below. This apparatus includes a laser oscillator 20 that outputs a high-energy excimer laser, a reflection mirror 27 that changes the direction of the laser light 21, and a long-axis homogenizer 22a and a short-axis homogenizer 22b for shaping the laser light into a square line beam. And a reflecting mirror 28 that changes the direction of the laser light, and a condensing lens 23 that condenses the line beam 24 on the amorphous silicon 51 on the substrate 50.
The substrate 50 on which the amorphous silicon film 51 is formed is placed in a vacuum chamber of a laser annealing apparatus, and the major axis (direction perpendicular to the paper surface) × short axis (direction parallel to the paper surface) of the amorphous silicon film 51 is about 200. A square line beam 24 of × 0.4 mm is irradiated. Further, in order to crystallize the entire surface of the amorphous silicon film 51, the substrate 50 is moved in the minor axis direction (arrow direction) at a feed pitch of 5 to 10% of the minor axis width of the line beam per shot of the line beam 24. ing. Therefore, the substrate 50 is irradiated with the laser beam 10 to 20 times in the same place.

After the amorphous silicon film 51 irradiated with the laser is melted (the melting temperature of silicon is 1200 ° C.), solidification starts from the edge portion of the melted region where the cooling rate is fast, and the solidified portion forms a growth nucleus to generate crystals. To do. Then, the same portion of the substrate 50 is irradiated with the laser a plurality of times, so that a crystal grows and a polycrystalline silicon film 52 having a high degree of crystallinity is generated.
By such laser annealing, a polycrystalline silicon film having crystal grains of 1 to 2 μm can be obtained.
JP 2003-282433 A

However, an apparatus using a laser has a problem that it is large and expensive, and the manufacturing cost of the product becomes high.
The present invention solves such conventional problems, and provides a thin film crystallization method capable of crystallizing an amorphous thin film in a short time with a simple apparatus, and also provides an apparatus for carrying out the method. The purpose is that.

Therefore, in the present invention, in a thin film crystallization method in which an amorphous thin film is melted and then recrystallized, a plasma generating gas introduced into a thin tube is ejected from the tip of the thin tube into the atmosphere to generate a micro plasma jet at the tip of the thin tube. The amorphous thin film is melted by irradiating the amorphous thin film with the microplasma jet in the atmosphere.
This method does not require a large-scale device. Further, since the high temperature plasma is used, the amorphous thin film can be melted in a very short time.

  Further, in the thin film crystallization method of the present invention, a thin tube is formed of an insulator, high frequency power is supplied to a coil provided around the thin tube, an induction electric field is generated inside the thin tube, and a plasma generated gas introduced into the thin tube is generated. Turn into plasma.

  Further, in the thin film crystallization method of the present invention, a thin tube is formed of metal, and a high-frequency power is applied to the thin tube to plasmify the plasma generation gas ejected from the tip of the thin tube.

In the thin film crystallization method of the present invention, the irradiation position of the microplasma jet on the amorphous thin film is sequentially moved.
Linear or planar crystallization can be realized by scanning the microplasma jet relatively one-dimensionally or two-dimensionally on the amorphous thin film.

In the thin film crystallization method of the present invention, the amorphous thin film is simultaneously irradiated with a plurality of microplasma jets generated at the tips of a plurality of thin tubes.
In this method, the entire amorphous thin film can be crystallized in a short time.

In the present invention, a thin film crystallization apparatus that recrystallizes after melting an amorphous thin film, a thin tube made of an insulator, a plasma generated gas supply means for introducing a plasma generated gas into one end of the thin tube, and a periphery of the thin tube A coil that surrounds the coil, a high-frequency power source that supplies high-frequency power to the coil, a facing position between the other end of the thin tube and the amorphous thin film, and a moving means that changes the distance between the other end of the thin tube and the amorphous thin film, A microplasma jet generated at the other end of the narrow tube is irradiated to an amorphous thin film disposed in the atmosphere.
Therefore, the amorphous thin film can be melted in a short time with a simple configuration. Further, the temperature and energy of the plasma acting on the amorphous thin film can be adjusted by controlling the distance between the other end of the thin tube and the amorphous thin film, the flow rate of the plasma generation gas, the high frequency power, and the like.

In the present invention, the thin film crystallization apparatus includes a thin tube made of metal, a plasma generation gas supply means for introducing a plasma generation gas into one end of the thin tube, a high frequency power source for supplying high frequency power to the thin tube, and the other end of the thin tube And a moving means for changing the facing position of the amorphous thin film, and the microplasma jet generated at the other end of the thin tube is irradiated to the amorphous thin film disposed in the atmosphere.
Therefore, the amorphous thin film can be melted in a short time with a simple configuration. Further, the temperature and energy of the plasma acting on the amorphous thin film can be adjusted by controlling the introduction flow rate of the plasma generation gas, the high frequency power and the like.

Further, in the thin film crystallization apparatus of the present invention, a plurality of capillaries are provided, positioning means for defining the relative positions of the capillaries are provided, and each microplasma jet generated at the other end of the capillaries is placed in the atmosphere. The non-crystalline thin film disposed on the substrate is irradiated.
In this apparatus, a large area of an amorphous thin film can be crystallized in a short time.

  In the thin film crystallization method and apparatus of the present invention, an amorphous thin film can be melted and recrystallized with an apparatus having an extremely simple structure compared to laser annealing, and the amorphous thin film can be recrystallized in the air in a short time. Melting and recrystallization are possible. Therefore, a polycrystalline thin film can be manufactured at low cost.

(First embodiment)
In the thin film crystallization method of the present invention, polycrystalline silicon is generated by irradiating an amorphous silicon film with a fine-sized plasma jet flame (microplasma jet) in the atmosphere.
FIG. 1 schematically shows an apparatus according to a first embodiment for carrying out this method. This apparatus includes a quartz pipe 34 that generates a microplasma jet 40, a coil 33 that generates a high-frequency electromagnetic field in the quartz pipe 34, a high-frequency power source 31 that supplies electromagnetic waves to the coil 33, and between the high-frequency power source 31 and the coil 33. , A gas supply source 36 for supplying a plasma generation gas such as argon, helium, oxygen, and nitrogen to the quartz pipe 34 through the gas introduction pipe 37, and a flow rate controller for controlling the flow rate of the plasma generation gas. , And a moving means (not shown) for changing the relative position (arrow a direction and arrow b direction) between the substrate 50 on which the amorphous silicon film 51 is formed and the microplasma jet 40. Yes.

The quartz pipe 34 has a total length of 100 mm, a cylindrical tip having an inner diameter of 2 mm, and is formed with a thin tip, and the diameter of the ejection port for ejecting the microplasma jet 40 is set to 100 μm. The high frequency power supply 31 outputs 144 MHz high frequency power (100 W), and the matching circuit 30 is adjusted so that the reflected wave returning from the coil 33 to the high frequency power supply 31 is minimized.
When a high frequency current supplied from the high frequency power supply 31 flows through the coil 33, the coil 33 generates an induction electric field in the quartz pipe 34. Therefore, for example, when argon (Ar) gas is used as the plasma generation gas, the argon atoms of the argon gas supplied from the gas supply source 36 and adjusted to a predetermined pressure by the flow rate regulator 35 and flowing into the quartz pipe 34 are Then, it is ionized by an induction electric field and becomes high-temperature (6000 to 7000 ° C.) plasma, which is pushed by the inflow pressure of argon gas and blows out into the atmosphere from the jet outlet at the tip of the quartz pipe 34. The ejected plasma does not diffuse due to the presence of the atmosphere, and generates a microplasma jet 40 having an electron density of 10 ¹⁷ per cm ³ . The energy of the microplasma jet 40 can be changed by controlling the flow rate regulator 35 that regulates the flow rate of argon gas or the power supplied from the high-frequency power source 31.

An amorphous silicon film 51 having a film thickness (about 0.3 μm) suitable for use in a TFT is formed on a glass substrate 50 by a method such as vapor deposition or sputtering, and the relative distance between the substrate 50 and the quartz pipe 34. Is adjusted so that the tip of the microplasma jet 40 reaches the amorphous silicon film 51, and the amorphous silicon film 51 is irradiated with the microplasma jet 40, the amorphous silicon film 51 at the irradiation position has a short time of several milliseconds or less. It melts by irradiation and crystallizes locally.
Further, the substrate 50 is moved relative to the quartz pipe 34 in the direction of the arrow b (scanning) at such a speed that the total irradiation time of the microplasma jet 40 to the same portion of the amorphous silicon film 51 is about several milliseconds. Then, crystallized silicon 52 is generated on the locus irradiated with the microplasma jet 40. If this scanning is performed two-dimensionally, a planar polycrystalline silicon film can be obtained.

FIG. 2 shows a result of measuring a Raman scattering spectrum at several points of a polycrystalline silicon thin film having an area of 5 × 5 cm ² formed by two-dimensional scanning. The horizontal axis of FIG. 2 indicates the wave value (cm ⁻¹ ) representing the Raman shift, the vertical axis indicates the intensity (arbitrary unit) of the Raman scattered light, and the line b indicates the measurement of the amorphous silicon film 51 before the microplasma jet irradiation. As a result, line a indicates the measurement result of the film 52 after the microplasma jet irradiation. The silicon film after the microplasma jet irradiation has a peak of Raman scattered light intensity at a wave value of 515 cm ⁻¹ representing the Raman shift of crystalline silicon, and its half width (about 5.2 cm ⁻¹ ) is that of single crystal silicon. Since it is almost equal to the half width, it can be seen that the silicon thin film is crystallized. The size of the generated crystal grains is 1 to 2 μm, which is about the same as in the case of laser annealing.

  In this apparatus, even when the film thickness of the amorphous silicon film is about 3 μm, the irradiation time at the same position of the microplasma jet 40 is increased, or the relative distance between the substrate 50 and the quartz pipe 34 is reduced. The entire film having this thickness can be melted and crystallized. In solar cells, the transport of light-injected carriers is in the direction of the film thickness, so that the thickness of the polycrystalline silicon film requires 2 to 3 μm. A polycrystalline silicon film having a wide film thickness range from about 0.3 μm suitable to 3 μm suitable for use in solar cells can be formed in a short time.

When the microplasma jet 40 is irradiated to the same position for 1 second or longer, the amorphous silicon film 51 at the irradiation position evaporates and a hole is formed in the glass substrate 50. Therefore, in this device, by controlling the irradiation time and irradiation position of the microplasma jet, precision processing such as providing a through hole, forming a groove, or cutting at a predetermined position in a substrate provided with a thin film Can also be applied.
Therefore, it is possible to perform fine processing of the substrate on which the amorphous silicon film is formed, selective crystallization of only a predetermined line shape or surface region, or crystallization of the entire film with this single apparatus.

  As described above, this thin film crystallization apparatus has an extremely simple structure as compared with a laser annealing apparatus, can recrystallize an amorphous film in the air in a short time, and manufacture a polycrystalline thin film at a low cost. can do. In addition, recrystallization can be performed on a material having a wide film thickness range, and recrystallization along a fine pattern, or entire microfabrication including a substrate can be performed.

  Although the case where a quartz pipe is used for plasma generation has been described here, the pipe may be formed of an insulating material other than quartz. The numerical values indicating the shape of the quartz pipe, the characteristics of the high-frequency power source, and the like shown here are merely examples and are not limited thereto.

(Second Embodiment)
In the second embodiment of the present invention, a thin film crystallization apparatus that generates a microplasma jet of plasma generation gas using a metal pipe will be described.
As shown in FIG. 3, this apparatus includes a metal pipe 60 that is thin like an injection needle, a high-frequency power source 31 that supplies electromagnetic waves to the metal pipe 60, and a matching circuit 30 that matches between the high-frequency power source 31 and the metal pipe 60. A gas supply source 36 that supplies a plasma generation gas to the metal pipe 60 through the gas introduction pipe 37, a flow rate regulator 35 that controls the flow rate of the plasma generation gas, a holder 61 that holds the metal pipe 60, and a holder A support 62 for supporting 61 at a constant height and a base 63 on which a substrate 50 on which an amorphous silicon film is formed are provided, and a moving means (non-moving means) for moving the substrate 50 on the surface of the base 63. (Shown).

In this apparatus, the distance a between the tip of the metal pipe 60 and the substrate 50 is fixed between 1 and 3 mm.
In the case where, for example, argon (Ar) gas is supplied from the gas supply source 36, the argon gas adjusted to a predetermined pressure by the flow rate regulator 35 flows into the metal pipe 60 and is ejected into the atmosphere from the tip of the metal pipe 60. . At the tip of the metal pipe 60 to which a high-frequency voltage is applied, an atmospheric pressure glow discharge is formed, which is very similar to the glow plasma formed under reduced pressure, and a microplasma jet composed of argon atom plasma is generated only at the tip of the metal pipe 60. To do.

The microplasma jet is irradiated onto the amorphous silicon film on the substrate 50 to recrystallize the silicon film. The processing at this time is the same as in the first embodiment.
However, in this apparatus, in order to maintain the atmospheric pressure glow discharge, it is necessary to keep the distance a between the tip of the metal pipe 60 and the substrate 50 constant. Unlike the apparatus of the first embodiment, the metal a A method for adjusting the melting of the amorphous silicon film by controlling the relative distance between the tip of the pipe 60 and the substrate 50 cannot be adopted.

(Third embodiment)
In the third embodiment of the present invention, a thin film crystallization apparatus capable of simultaneously recrystallizing a large area will be described.
As shown in FIG. 4, this apparatus has a microplasma array 70 including a plurality of metal pipes 60 that simultaneously generate a plurality of microplasma jets. The microplasma array 70 includes a plurality of metal pipes 60. And a storage container 71 for confining the plasma generation gas introduced from the gas introduction pipe 37 in cooperation with the copper plate 72. The electromagnetic wave from the high frequency power supply 31 is supplied to each metal pipe 60 via the copper plate 72.

Argon gas supplied from the gas supply source through the gas introduction pipe 37 flows into the space surrounded by the storage container 71 and the copper plate 72, and through the holes of the plurality of metal pipes 60 whose relative positions are fixed by the copper plate 72. , And ejected into the atmosphere on the side where the substrate 50 exists. Further, a high frequency voltage of a high frequency power supply 31 is applied to each metal pipe 60 via a copper plate 72, and a micro plasma jet made of argon atom plasma is generated at the tip of each metal pipe 60.
By irradiating the amorphous silicon film on the substrate 50 simultaneously with the plurality of microplasma jets, a wide portion of the silicon film can be recrystallized at the same time. By scanning, the entire surface of the amorphous silicon film can be crystallized in a short time.

Here, the case where a plurality of metal pipes according to the second embodiment are provided has been described, but a plurality of the quartz pipes according to the first embodiment are provided in the microplasma array 70 so that their relative positions are fixed. Also good.
In each embodiment, recrystallization of silicon has been described. However, the apparatus and method of the present invention can be widely used for recrystallization of substances other than silicon.

  The thin film crystallization method and apparatus of the present invention can be used to manufacture various crystallized films used for electronic devices, optical elements, ornaments, etc., including polycrystalline silicon thin films used for TFTs and solar cells. it can.

The figure which shows the structure of the thin film crystallization apparatus in the 1st Embodiment of this invention. The figure which shows the Raman spectrum of the amorphous thin film and the crystallized thin film produced | generated by the thin film crystallization method in the 1st Embodiment of this invention The figure which shows the structure of the thin film crystallization apparatus in the 2nd Embodiment of this invention. The figure which shows the structure of the thin film crystallization apparatus in the 3rd Embodiment of this invention. The figure which shows the constitution of the conventional laser annealing equipment

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 Laser oscillator 21 Laser beam 22a Long axis homogenizer 22b Short axis homogenizer 23 Condensing lens 24 Line beam 27 Reflection mirror 28 Reflection mirror 30 Matching circuit 31 High frequency power supply 33 Coil 34 Quartz pipe 35 Flow rate regulator 36 Gas supply source 37 Gas introduction pipe 40 Microplasma jet 50 Substrate 50
51 Amorphous silicon 52 Polycrystalline silicon 60 Metal pipe 61 Holder 62 Support column 63 Base 70 Microplasma array 71 Storage container 72 Copper plate

Claims (8)

In a thin film crystallization method of recrystallizing after melting an amorphous thin film,
A plasma generating gas introduced into a thin tube is ejected from the tip of the thin tube into the atmosphere to generate a microplasma jet at the tip of the thin tube, and the amorphous thin film is irradiated with the microplasma jet in the air. A thin-film crystallization method characterized by melting   The thin tube is formed of an insulator, high frequency power is supplied to a coil provided around the thin tube to generate an induction electric field inside the thin tube, and the plasma generation gas introduced into the thin tube is turned into plasma. The thin film crystallization method according to claim 1.   2. The thin film crystallization method according to claim 1, wherein the thin tube is made of metal, and the plasma generation gas ejected from the tip of the thin tube is made into plasma by applying high frequency power to the thin tube.   The thin film crystallization method according to claim 1, wherein an irradiation position of the microplasma jet to the amorphous thin film is sequentially moved.   2. The thin film crystallization method according to claim 1, wherein the amorphous thin film is simultaneously irradiated with the plurality of microplasma jets generated at the tips of the plurality of thin tubes. In a thin film crystallization apparatus that recrystallizes after melting an amorphous thin film,
A capillary tube made of an insulator,
A plasma generation gas supply means for introducing a plasma generation gas into one end of the narrow tube;
A coil surrounding the periphery of the capillary,
A high frequency power source for supplying high frequency power to the coil;
A microplasma jet generated at the other end of the capillary tube, the opposite position of the other end of the capillary tube and the amorphous thin film, and a moving means for changing the distance between the other end of the capillary tube and the amorphous thin film. A thin film crystallization apparatus for irradiating the amorphous thin film disposed in the atmosphere. In a thin film crystallization apparatus that recrystallizes after melting an amorphous thin film,
Tubules made of metal,
A plasma generation gas supply means for introducing a plasma generation gas into one end of the narrow tube;
A high frequency power supply for supplying high frequency power to the narrow tube;
A moving means for changing a facing position between the other end of the capillary and the amorphous thin film, and irradiating the amorphous thin film disposed in the atmosphere with a microplasma jet generated at the other end of the capillary A thin-film crystallization apparatus. The non-crystalline thin film including a plurality of the thin tubes and a positioning means for defining a relative position of the plurality of thin tubes, and each microplasma jet generated at the other end of the plurality of thin tubes is disposed in the atmosphere. The thin film crystallization apparatus according to claim 6, wherein the thin film crystallization apparatus is irradiated with light.

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