KR100387522B1 - Apparatuses and methods for heat treatment of semiconductor films upon thermally susceptible non-conducting substrates - Google Patents

Abstract

The present invention relates to an apparatus and method for heat-treating a semiconductor thin film on a non-conductive substrate having poor thermal stability within an allowable temperature range of a non-conductive substrate, comprising: (a) a direction provided near a semiconductor film and parallel to the plane of the semiconductor film; An induction coil positioned such that an induction current is applied thereto, (b) a magnetic core installed inside or outside the induction coil, and (c) a temperature below the non-conductive substrate so that the semiconductor film can be inductively heated. It consists of including a heating plate to heat it up to.

By using the low temperature heat treatment apparatus of the present invention, in heat treatment of a semiconductor film on a non-conductive substrate, only the semiconductor film can be heat-treated in a short time at a temperature that does not damage or deform the non-conductive substrate, which is poor in thermal stability, and in particular, alternately for heating. Since the magnetic field is increased by the magnetic core, the application efficiency of the induced electromotive force is increased, and the distribution of the induced magnetic field is limited only to the surface of the semiconductor film, thereby preventing problems such as heating the reactor walls. In addition, in some cases, since a charging cassette for mounting a plurality of non-conductive substrates can be used, there is also an advantage that a mass heat treatment process and a continuous heat treatment process are possible.

Description

Apparatuses and methods for heat treatment of semiconductor films upon thermally susceptible non-conducting substrates}

The present invention relates to an apparatus and method for heat-treating a semiconductor thin film on a non-conductive substrate having poor thermal stability within an allowable temperature range of the non-conductive substrate, and more particularly, to a liquid crystal display (LCD) and an organic light emitting diode (OLED). The present invention provides a heat treatment technique for polycrystalline silicon thin film transistors (poly-Si TFT) and PN diodes (semiconductor thin film) on a glass substrate (non-conductive substrate) having various applications such as solar cells.

Liquid crystal displays (LCDs) and organic light emitting diodes (OLEDs) are rapidly growing technologies in the flat display field. Currently, these display systems employ an active matrix circuit configuration using thin film transistors (TFTs), which require the fabrication of TFTs on glass substrates.

Typically, the TFT-LCD uses a TFT composed of amorphous silicon as the active layer (i.e., a-Si TFT LCD). Recently, attention has been focused on the development of TFTs using polycrystalline silicon films (i.e., poly-Si TFT LCDs) instead of amorphous silicon films due to the advantages of excellent resolution and simultaneous integration with peripheral drive circuits. In the OLED field, the use of the polycrystalline silicon TFT provides a clear advantage over the amorphous silicon TFT because the current driving ability of the polycrystalline silicon TFT is much better than that of the amorphous silicon TFT, thereby exerting more excellent performance.

The biggest challenge when manufacturing polycrystalline silicon devices on glass substrates in use today is that they must be heat treated at temperatures that the organic substrate can withstand. The glass deforms easily when exposed to a long time above 500 ° C. In the manufacture of polycrystalline silicon devices, heat treatment processes that require long-term heat treatment at high temperatures include crystallization of an amorphous silicon film and electrical activation of an implantation dopant for P (or N) type bonding. These heat treatment processes must be carried out for a long time at a high temperature, so that damage or deformation of the glass cannot be avoided.

Various methods have been developed to solve this problem. The examples of the polycrystalline silicon film and the dopant activation process are as follows.

(One) Crystallization Heat Treatment of Amorphous Silicon Films for Formation of Polycrystalline Silicon Films

A polycrystalline silicon film is usually prepared by first depositing an amorphous silicon film by chemical vapor deposition method (CVD) and then crystallizing it by heat treatment.

Solid phase crystallization (SPC) is the most common method for crystallizing amorphous silicon films. This method heats an amorphous silicon film at a temperature of about 600 ° C. for several hours to several tens of hours, and typically processes a glass substrate in a furnace equipped with a resistance heater. SPC method is 50-100 cm.sup.2 / Vs. A high quality polycrystalline silicon device with electron mobility is provided. However, this method must be carried out for a long time at a high temperature, there is a problem that damage and / or deformation of the glass substrate is inevitable.

Accordingly, various methods have been developed for converting amorphous silicon into polycrystalline silicon at low temperatures without damaging the glass substrate. Representative examples include Excimer Laser Crystallization (ELC) and Metal Induced Crystallization (MIC) methods.

The ELC method is a method of melting and recrystallizing an amorphous silicon film using instantaneous irradiation of an excimer laser. This method theoretically offers the possibility to heat-treat the amorphous silicon film mounted thereon at an optimum temperature without damaging the glass substrate. However, this method has a fatal disadvantage that cannot be used for mass production. Since the grain structure of the polycrystalline silicon film obtained by this method is very sensitive by laser beam energy, uniformity and device characteristics of the grain structure cannot be obtained. In addition, because the beam size of the laser is relatively small, multiple lasers or multiple shots are required to crystallize a large glass substrate. Since it is difficult to fine tune the laser, multiple irradiations lead to inhomogeneities. The surface of the obtained polycrystalline silicon film is rough, which adversely affects the characteristics of the device. In addition, when the deposited amorphous silicon has a high hydrogen content (a common phenomenon in Plasma Enhanced Chemical Vapor Deposition (PECVD)), this method has a problem of hydrogen eruption. In order to prevent the hydrogen ejection, heat treatment for dehydrogenation is required for a long time (> 2 hours) at a high temperature (450 ~ 480 ℃). In addition to these problems, the equipment for the ELC process is complex, very expensive and difficult to maintain.

The MIC method is a method of inducing crystallization at low temperature by adding a metal element (Ni. Pd, Au, Ag, Cu, etc.) to the amorphous silicon film. This method can achieve crystallization at a low temperature of less than 600 ℃, but the size of the crystal grains and poor crystallinity is poor driving characteristics of the device. In particular, the metal flows into the channel region of the transistor, which increases the leakage current. Another problem with this method is that metal silicide is formed during the process. Metal silicide is undesirable because it remains during the etching process.

(2) heat treatment for activation of dopant

In addition to the crystallization process, another example where high temperature heat treatment is required is the activation process of the dopant. In order to form n-type (or p-type) regions, such as the source and drain regions of the TFT, dopants such as arsenic, phosphorus or boron may be formed by silicon implantation using ion implantation or plasma doping. Inject in. After doping the dopant, the silicon is heat treated (activation heat treatment) for electrical activation. Similar to the crystallization heat treatment, it is generally carried out in a reactor equipped with a resistance heater. Since this process is performed for a long time at a temperature close to 600 ° C, a new method for heat treatment at low temperature is required. Excimer Laser Anneals (ELA) and Rapid Thermal Anneals (RTA) have been developed for this purpose.

ELA is implemented with the same processing mechanism as ELC, which rapidly remelts and crystallizes polycrystalline silicon with nano-second laser pulses. However, problems found in the ELC method also appear here. The rapid thermal change during the ELC process causes high thermal stress not only on glass but also on polycrystalline silicon film, thereby degrading the reliability of the device.

The RTA method requires high temperature but short duration. That is, the RTA method typically runs the substrate at temperatures close to 700-1000 ° C., but the process proceeds relatively very quickly, i.e. for a few minutes to a few seconds. As an RTA heating source, an optical heating source such as tungsten-halogen or Xe arc lamp is used. The problem with the RTA method is that light irradiation from these optical heating sources has a wavelength range for heating not only a silicon film but also a glass substrate. . Thus, the glass substrate is heated and damaged during the process.

Accordingly, an object of the present invention is to solve the problems of the prior art and the technical problems that have been requested from the past.

When the crystallization of the amorphous silicon film deposited on the glass substrate by heat treatment to crystallize, when the graphite heating plate is installed under the glass substrate and stirring magnetic flux is applied to the amorphous silicon film, the crystallization heat treatment despite the low process temperature and short process time Has found a possible patent application. After more in-depth research and experimentation with the present invention, the invention exhibits an excellent effect that cannot be achieved by the prior art, but when the applied energy is increased to provide high induced electromotive force to the amorphous silicon film, Since the temperature rises together, in order to change the crystallization temperature, it is inconvenient to change the size and thickness of the substrate in consideration of the penetration depth, and high power is applied to induce sufficient electromotive force to the silicon film. It confirmed that there was a task that should be.

Accordingly, an object of the present invention is to heat treatment at a low process temperature and a short process time to enable heat treatment of the upper semiconductor film without damaging the lower non-conductive substrate, and also to effectively exhibit the above effects despite the application of an appropriate current. It is to provide a heat treatment apparatus and a method thereof.

1 is a schematic configuration diagram of a low temperature heat treatment apparatus using a wound induction coil;

2 is a schematic configuration diagram of a low temperature heat treatment apparatus using a spiral induction coil;

3 to 5 are schematic diagrams of devices according to an embodiment of the present invention;

6 is a schematic view showing the crystallization behavior of silicon when solidifying crystallized according to the present invention;

7 is a graph showing the solid state crystallization behavior according to the conventional heat treatment and the method of the present invention;

8A and 8B are scanning electron micrographs of the grain structure after solid phase crystallization obtained by the present invention and the conventional heat treatment;

9 is a configuration diagram showing a state of metal induction crystallization according to the present invention;

10 is a schematic view showing a state of metal-induced side crystallization according to the present invention;

11A-11C are micrographs showing the degree of lateral crystallization in FIG. 10;

12 is a graph showing the metal induced side crystallization distance according to the change of the coil current;

Figure 13a is a graph showing the sheet resistance value according to the heat treatment time in the heat treatment furnace and the conventional heat treatment furnace of the present invention;

Figure 13b is a graph showing the sheet resistance value with heat treatment temperature and time in the heat treatment according to the present invention.

Description of the main signs in the drawings :

100: low temperature heat treatment apparatus 200: silicon film

300: glass substrate 400: heating plate

500: induction coil

The low temperature heat treatment apparatus of the present invention for achieving the above object is a device for heat-treating a semiconductor film on a non-conductive substrate having poor thermal stability,

(a) an induction coil disposed near the semiconductor film and positioned to apply an induction current in a direction parallel to the plane of the semiconductor film;

(b) a magnetic core installed inside or outside the induction coil; And

(c) a heating plate disposed below the non-conductive substrate and heating the semiconductor film to a temperature at which the semiconductor film can be induction heated.

Representative examples of the semiconductor film may include an amorphous or polycrystalline silicon film, and representative examples of the nonconductive substrate may include a glass and a plastic substrate.

According to the apparatus of the present invention, it is possible to heat-treat only a silicon film thereon without damaging a substrate having a poor thermal stability such as glass, for example, crystallizing an amorphous silicon film within an allowable temperature of a glass substrate, or It is possible to electrically activate the dopant implanted into the polycrystalline silicon within the allowable temperature of the substrate.

The silicon film is deposited on a glass substrate by various methods, in the case of crystallization heat treatment, an amorphous state to be crystallized to polycrystal, and in the case of activation heat treatment of a dopant (n-type or p-type impurity).

The heating plate directly heats the non-conductive substrate and ultimately heats the semiconductor film on the non-conductive substrate. The type of the heating plate can be classified into two types according to the method of heating the heating plate itself.

The first type is in which the heating plate is made of a highly conductive metal or graphite, which is self-heated by the heating mechanism of the eddy currents formed on its surface by the stirring magnetic field from the induction coil.

The second type is a method in which the heating plate is made of an electrically nonconductive material, which prevents induction heating by the stirring magnetic field from the induction coil and independently heats it by an external heating source such as a resistance heater or a lamp heater. As a material of such a heating plate, AlN (Aluminum Nitride), BN (Boron Nitride), etc., which have high specific resistance and good thermal conductivity, may be used.

The second type of heating plate provides a further advantage in that the degree of heating of the substrate can be controlled independently of the induction heating for crystallization (or activation) in systems where the magnetic strength is varied. In both types, the temperature of the substrate must be kept below the thermal deformation temperature of the substrate. For example, if the substrate is a glass substrate it should be maintained at a temperature below 500 ° C., which is the temperature at which the glass can be damaged. In some cases, in order to improve the uniformity of the process, the heating plate may be configured to perform linear motion or rotational motion.

The magnetic core is composed of a laminated metal core or a ferromagnetic core, and exhibits the following advantages as compared to the case consisting of only an induction coil. First, even with low induction power, the strength of the induction magnetic field is substantially improved. Second, make the distribution of magnetic flux more uniform. Third, by concentrating the stirring magnetic flux on the semiconductor film, the efficiency of the heat treatment is increased, and the conductive substrates (eg, the reactor wall, the external heating device) installed around the heating plate are prevented from being interfered by the magnetic flux.

The magnetic core is provided in the induction coil as long as it can achieve the above effects, and any structure can be used. Preferred examples are as follows.

The first structure is such that the magnetic core is in the form of a plate and the induction coil is mounted on the bottom thereof so that the upper part of the induction coil is sealed by the magnetic core and only the lower part is exposed in the direction of the specimen. Therefore, the distribution of the induced magnetic field can be locally generated only on the surface of the specimen, thereby preventing the reactor wall or the like from being heated by the leakage magnetic flux.

The second structure has a magnetic core And an induction coil wound around the middle thereof, the current applied to the induction coil forms an amplified induction magnetic field in the magnetic core, which in turn is applied perpendicularly to the semiconductor film from one end by turning the magnetic core. And a magnetic flux distribution entering the other end. Therefore, a uniform stirring magnetic flux can be applied to the semiconductor film in the vertical direction. The device having such a structure has the advantage that the continuous work can be performed by continuously moving the specimen located below.

The third structure is a magnetic core with vertical cross section And the induction coil is wound on its left vertical portion, so that the current applied to the induction coil forms an amplified induction magnetic field in the magnetic core, which induces a magnetic field from the upper end to the lower end of the right vertical portion with the middle portion separated. (Or from the lower end to the upper end). Thus, all magnetic flux can be applied exactly in the vertical direction to the specimen. In this structure, the induced electromotive force is applied to the silicon film surface in the horizontal direction, thereby maximizing the heat treatment enhancement effect by the induced electromotive force, and there is no need to readjust the magnetic flux distribution according to the thickness of the glass substrate. The advantage is that the substrates can be processed simultaneously, increasing the production speed.

The apparatus of the present invention exhibits remarkable effects in all of solid state crystallization (SPC), metal induction crystallization (MIC), metal induction side crystallization (MILC) of amorphous silicon, and also has a great effect on the electrical activation of ion implanted polycrystalline silicon.

The invention also relates to a method of heat treating a semiconductor film on such a substrate without damaging a non-conductive substrate having poor thermal stability using such a device. Specifically, while the semiconductor film is heated by a heating apparatus to a temperature at which the semiconductor film can be inductively heated without damaging or deforming the non-conductive substrate, an alternating magnetic field from the induction coil is concentrated on the semiconductor film by the magnetic core. It is a method of heat-processing the said semiconductor film by making it apply.

When the semiconductor film on the nonconductive substrate is a silicon film on a glass substrate, the heating temperature by the heating plate is in the range of 200 to 500 ° C.

When the silicon film is an amorphous silicon film deposited on a glass substrate, it is crystallized by heat treatment, and when the P-type or N-type dopant is an ion implanted polycrystalline silicon film, it is activated by heat treatment. The crystallization of amorphous silicon may be any of solid phase crystallization, metal induced crystallization, or metal induced side crystallization.

Hereinafter, for convenience of description, the semiconductor is limited to silicon and the non-conductive substrate is limited to the glass substrate.

Given that the induced electromotive force by the stirring magnetic field is an important factor in promoting the crystallization, the induced electromotive force by the stirring magnetic field is Faraday's law, that is,

EMF = 10N ^-8 dφ / dt

Where N is the number of revolutions of the coil, φ is the magnetic flux considering the area of the specimen, and dφ / dt is the frequency of the stirring magnetic flux. Therefore, it can be seen that the induced electromotive force depends on the magnitude of the stirring flux and the frequency. The stirring magnetic flux has a frequency of 10 Hz to 10 MHz, which varies depending on the shape of the graphite heating plate and the induction coil. However, if the frequency is lower than the frequency, the induced electromotive force is small, which promotes crystallization and heating of the substrate temperature is difficult. It becomes difficult to maintain the temperature. Since the predetermined temperature at which the graphite heating plate is heated is a low temperature of 200 to 500 ° C., the amorphous silicon film can be crystallized even at a very low temperature compared to the conventional method, and the dopant of the polycrystalline silicon film can be activated.

As described above, the reason why the induced electromotive force increases the heat treatment effect is not clearly understood, but the following two mechanisms can be considered.

The first expected mechanism is to locally heat the amorphous silicon film (if applied to crystallization heat treatment) or the polycrystalline silicon film (if applied to activation heat treatment) by eddy currents generated from the induced electromotive force. Amorphous silicon or polycrystalline silicon has a very large resistivity at room temperature. For example, the resistivity of amorphous silicon is 10 ⁶ to 10 ¹⁰ Ωcm. Therefore, local heating by joule heating does not occur unless the temperature of the specimen is artificially raised by external heating. However, when the temperature of the amorphous silicon or polycrystalline silicon rises by external heating, the specific resistance decreases rapidly. For example, the specific resistance of the amorphous silicon is 500 to 10 to 0.01 Ωcm. This specific resistance value is close to the specific resistance value (1 to 0.001 Ωcm) of the graphite used as the heating plate in the present invention, and thus may cause an induction heating effect. In spite of such local heating, since the temperature of the lower glass substrate is kept below 500 ° C., the deformation of the substrate can be suppressed.

The second expected mechanism is that the movement of atoms is activated by induced electromotive force (emf). In the case of silicon, point defects such as vacancy, self-interstitial, and impurities exist in the form of trapping electrons or holes, and are known to have negative or positive charges. have. These charged defects can be energized by induced electromotive force. The increase in atomic mobility due to the formation of electric fields has already been reported academically. (Eg, “Field-Enhanced Diffusion” in silicon, see SM Sze “VLSI Technology” (2 ^nd ed. McGraw Hill, 1998), P. 287).

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the following examples are only for illustrating the present invention, and the scope of the present invention is not limited thereto.

Figure 1 shows a schematic configuration of a low temperature heat treatment apparatus using a wound induction coil as an embodiment of the present invention described above. The low temperature heat treatment apparatus 100 of FIG. 1 includes a graphite heating plate 400 for heating a glass substrate 300 on which an amorphous silicon film 200 is deposited, and a winding type induction coil 500 for inducing stirring magnetic flux. It is. When an alternating current is applied to the wound induction coil 500 formed of a water-cooled copper pipe, the stirring magnetic flux F is generated therein. The stirring magnetic flux (F) is used for two purposes, by generating an eddy current in the lower graphite heating plate 400 and heating to a desired temperature, and at the same time accelerates the movement between atoms by the induced electromotive force generated in the induction coil 500 to amorphous Promote crystallization of the silicon film 200.

As such, it is necessary to increase the magnitude of the magnetic field of the induction coil 500 in order to increase the agitation action between atoms, and at this time, the temperature of the graphite heating plate 400 is maintained at a low temperature of about 200 ~ 500 ℃ shall. In order to implement this, the thickness and shape of the graphite heating plate 400 may be appropriately controlled in consideration of the penetration distance of the induction magnetic field.

2 shows a schematic configuration of a low temperature heat treatment apparatus using a spiral induction coil as one embodiment of the present invention. In the low temperature heat treatment apparatus 110 of FIG. 2, the spiral induction coil 510 made of a water-cooled copper tube applies horizontally the stirring magnetic flux F to the amorphous silicon film 210 on the glass substrate 310.

Figure 3 shows a schematic configuration of a low temperature heat treatment apparatus according to an embodiment of the present invention using a magnetic core in addition to the induction coil. The low temperature heat treatment apparatus 120 of FIG. 3 has a structure in which a spiral induction coil 520 is closed by an upper portion of a magnetic core 620 of a disk shape and a lower portion thereof is opened. The material of the heating plate 420 is made of AlN or BN having a high specific resistance and good thermal conductivity, and is heated to 200 to 500 ° C by a separate heating device (not shown) installed at the bottom. Since the induction coil 520 is opened only to the silicon film 220 by the magnetic core 620, the induction magnetic field is increased by the magnetic core 620, so that the application efficiency of the induced electromotive force is increased, and the distribution of the induction magnetic field is increased. Is limited to only the surface of the silicon film 220 on the glass substrate 320 to prevent problems such as heating the walls (not shown) of the reactor.

Figure 4 shows a low temperature heat treatment apparatus according to another embodiment of the present invention. The low temperature heat treatment apparatus 130 of FIG. 4 has a vertical cross-sectional shape as shown in the drawing. An induction coil 530 is wound around a central portion of the phosphorous core 630, and both ends A and B of the magnetic core 630 are provided above the glass substrate 330. The glass substrate 330 is moved from outside to a box furnace 830 by the transfer device 730, and the transfer device 730 also heats the glass substrate 330 to a predetermined temperature. do. The current applied to the induction coil 530 produces an amplified induction magnetic field in the magnetic core 630, which in turn turns the magnetic core 630 perpendicular to the silicon film 230 from one end A thereof. Direction, and forms a magnetic flux distribution entering the other end B. As shown in FIG. Therefore, a uniform stirring magnetic flux may be applied to the silicon film 230 vertically. The induction coil 530 and the magnetic core 630 should be properly cooled by cooling water, and an insulator 832 is installed on the inner wall of the box furnace 830 to transfer the reaction heat to the induction coil 530 and the magnetic core 630. Prevent it. On the other hand, since the openings 834 are respectively provided on the left and right sides of the box furnace 830, the transfer device 730 can be moved, and thus the glass substrate 430 is uniformly heated and continuous operation is possible.

Figure 5 shows a low temperature heat treatment apparatus according to another embodiment of the present invention. In particular, the structure of this embodiment makes it possible to heat-treat multiple glass substrates in one process (ie, batch process). Low temperature heat treatment apparatus 140 of Figure 5 has a vertical cross-sectional shape An induction coil 540 is wound in the center of the left vertical portion 642 of the phosphorous core 640 and passes through the glass substrate 340 through the spaced center portion (between C and D) of the right vertical portion 644. It is structure to let. Both the left vertical portion 642 and the right vertical portion 644 of the magnetic core 640 are positioned outside the box 840 in which the insulator 842 is provided on the inner wall, but the right vertical portion 664 The two ends C and D spaced apart have a structure that is somewhat introduced into the box 840. The glass substrate 340 on which the silicon film 240 is deposited is placed on the transfer device 740 and enters through the opening 844 of the box 340. As in FIG. 4, all magnetic fluxes are applied to the glass substrate 340 exactly vertically, and the induction electromotive force is applied to the surface of the silicon film 240 in the horizontal direction, thereby maximizing the heat treatment enhancement effect by the induction electromotive force. The magnetic flux distribution does not have to be readjusted according to the thickness of the glass substrate 340, which is very convenient. In addition, as shown in the drawing, a plurality of glass substrates 340 can be mounted on the charging cassette 940 made of AlN or quartz and processed simultaneously, thereby increasing production speed. Since the stirring magnetic flux is transmitted between the substrates due to the material of the charging cassette 940 and the glass substrate 340 having no magnetic properties, the same magnetic flux is applied in the vertical direction of the substrate.

Example 1 Solid Phase Crystallization of Amorphous Silicon Membrane

As shown in FIG. 6, an amorphous silicon film 250 was deposited on the glass substrate 350 by a low pressure chemical vapor deposition to a thickness of 1000 μs. Then, an organic substrate 350 on which the amorphous silicon film 250 is deposited is applied by applying a current of 5 A to the low temperature heat treatment apparatus 130 of FIG. 3 in which an induction coil having a diameter of 15 cm is wound at eight revolutions. Was heat treated at 300 ° C. for 5 hours. The magnetic core used at this time was MnZn Ferrite, and the saturation magnetic flux density was about 3 KiloGauss. For the comparative experiment, the same glass substrate 350 was heat-treated at 600 ° C. for 10 hours using a resistance heating tubular furnace which is a general heat treatment furnace. In order to examine the crystallization behavior with these time changes, X-ray diffraction analysis was performed.

7 shows a graph of these X-ray diffraction analysis. In the case of a silicon film treated in a general heat treatment furnace, crystallization started after 5 hours and crystallization was completed when 7 hours passed. It can be seen that the silicon film used is crystallized at a time point when one hour has elapsed and the crystallization is completed rapidly.

8A and 8B show photographs obtained by scanning electron microscopy of the grain structure of the silicon film at the time when the crystallization is completed in the above experiment, and the silicon film heat-treated at 300 ° C. for 1 hour using the apparatus of the present invention. It can be seen that the grain structure (FIG. 8A) and the grain structure (FIG. 8B) of the silicon film heat-treated at 600 ° C. for 7 hours using a general heat treatment furnace are very similar. That is, as shown in Figure 8a, it can be seen that by the low temperature heat treatment crystallization of the present invention, polycrystalline silicon having high crystallinity is formed as a coarse grain structure having a grain size of 2 to 3 µm.

Example 2: Metal-Induced Crystallization of Amorphous Silicon Membranes

As shown in FIG. 10, an amorphous silicon film 260 was deposited on the glass substrate 360 by a low pressure chemical vapor deposition method at a thickness of 1000 mW, and Ni 960 was deposited thereon by a sputtering method at 30 mW. The diameter, the number of turns and the frequency of use of the induction coil for the stirring magnetic flux heat treatment are the same as in Example 1. In the state of applying a current of 5A, the heat treatment for 1 hour at a temperature of 200 ℃, 250 ℃, 300 ℃, 350 ℃ and 400 ℃, respectively, the results are shown in Table 1 below. As shown in Table 1, when performing the metal induction crystallization method according to the present invention, it can be confirmed that crystallization is possible at a temperature of less than 250 ℃.

Example Applied current Heat treatment temperature / hour Crystallization 2-1 5A 200 ℃ / 1 hour X 2-2 5A 250 ℃ / 1 hour O 2-3 5A 300 ℃ / 1 hour O 2-4 5A 350 ℃ / 1 hour O 2-5 5A 400 ℃ / 1 hour O

Example 3: Metal-Induced Lateral Crystallization of Amorphous Silicon Membranes

As shown in FIG. 10, an amorphous silicon film was deposited on the glass substrate by a low pressure chemical vapor deposition method to a thickness of 1000 GPa, and Ni was deposited on a selective portion of the glass substrate to 30 GPa by the sputtering method.

For a clearer comparison, experiments were performed by patterning with a T-shape or the like as shown in FIG. 11A. The outer portion of the T-shaped pattern is Ni deposited and the inside is a region where Ni is not deposited. The result of heat-treating the specimens at 500 ° C. for 7 hours using a general heat treatment furnace is shown in FIG. 11B, and the result of heat treatment at 430 ° C. for 1 hour using the apparatus of the present invention is shown in FIG. 11C. In the apparatus of the present invention, the diameter, rotational speed, and magnetic core of the induction coil for the stirring magnetic flux heat treatment were the same as those in Example 1, and a current of 40 A was applied.

As shown in the figure, in the case of using a general heat treatment furnace (FIG. 11B), in spite of a long time heat treatment, lateral growth occurred at a relatively short distance of about 10 mu m, but in the case of using the apparatus of the present invention (FIG. 11C). Despite the heat treatment for a short time, it can be seen that lateral growth occurred at a long distance of about 25 μm.

12 is a graph showing the distance of metal induced side crystallization according to the current change of the induction coil. According to the graph, it can be seen that the crystallization distance rapidly increases when the applied current is 1A or more, and the stirring magnetic flux density has a decisive influence on the metal induction side crystallization rate.

Example 4 Dopant Activation of Crystalline Silicon Film

An amorphous silicon film deposited on a glass substrate with a thickness of 500 mm 3 was heat-treated at 300 ° C. for 1 hour using the apparatus 130 of FIG. 3 to crystallize into a polycrystalline silicon film. In the apparatus used, the diameter, the number of revolutions, and the magnetic core of the induction coil were the same as in Example 1. Phosphorus as an N-type dopant was ion-implanted into the polycrystalline silicon film thus obtained by a plasma doping apparatus using PH ₃ gas. The pressure of the PH ₃ gas was ₃ mTorr and the acceleration voltage was 20 KeV. The polycrystalline silicon film thus implanted was heat-treated in the same apparatus and the general heat treatment furnace, respectively.

Fig. 13A shows the change of the sheet resistance values with the change of the heat treatment time as a graph. In the case of using a general heat treatment furnace, the sheet resistance value is lowered to 700 Ω / cm 2 over 2 hours, whereas the apparatus of the present invention is used. In this case, it can be seen that a low sheet resistance value of 200? Figure 13b shows the change in sheet resistance with time at various temperatures using the device of the present invention, it can be seen that sheet resistance of less than 1000Ω / ㎠ at 350 ℃, 30 minutes can be obtained. .

Other applications

The subject matter of the present invention is not limited to a specific object and can be variously applied within the scope of the present invention. As a specific example, the apparatus and method of the present invention are used in the field of display, microelectronic, solar cell, etc., where an indium-tin-oxide (ITO) or metal film on a glass (or plastic) substrate is heat treated. May be used. The same concept as the present invention can also be used for a number of processes that require heat treatment of conductor films as well as semiconductors on non-conductive substrates (typically glass or plastic), which are poor in thermal stability.

Those skilled in the art to which the present invention pertains will be able to make various applications and modifications within the scope of the present invention based on the above contents.

By using the low temperature heat treatment apparatus of the present invention, in heat treatment of a semiconductor film on a non-conductive substrate, only the semiconductor film can be heat-treated in a short time at a temperature that does not damage or deform a non-conductive substrate, which is poor in thermal stability, and in particular, alternately for heating. Since the magnetic field is increased by the magnetic core, the application efficiency of the induced electromotive force is increased, and the distribution of the induced magnetic field is limited only to the surface of the semiconductor film, thereby preventing problems such as heating the reactor walls. In addition, in some cases, since a charging cassette for mounting a plurality of non-conductive substrates can be used, there is also an advantage that a mass heat treatment process and a continuous heat treatment process are possible.

Claims (12)

An apparatus for heat-treating a semiconductor film on a nonconductive substrate having poor thermal stability, (a) an induction coil disposed near the semiconductor film and positioned to apply an induction current in a direction parallel to the plane of the semiconductor film; (b) a magnetic core installed inside or outside the induction coil; And and (c) a heating plate installed under the non-conductive substrate, the heating plate heating the semiconductor film to a temperature at which the semiconductor film can be inductively heated. 2. The apparatus of claim 1, wherein the semiconductor film is an amorphous or polycrystalline silicon film and the nonconductive substrate is a glass and a plastic substrate. 3. The silicon film according to claim 2, wherein the silicon film is an amorphous silicon film deposited on a glass substrate, which is crystallized after heat treatment, or is a silicide film activated by a dopant (P-type or N-type dopant) injected as a polycrystalline silicon film to be activated after the heat treatment. Characterized in that the device. The heating mechanism according to any one of claims 1 to 3, wherein the heating plate is made of a highly conductive metal or graphite, so that the heating mechanism of the eddy currents formed on its surface by the stirring magnetic field from the induction coil. Self-heating, or electrically non-conductive material, to prevent induction heating by the stirring magnetic field from the induction coil and independently heating by an external heating source such as a resistance heater or a lamp heater. Device. 4. The magnetic core according to any one of claims 1 to 3, wherein the magnetic core is in the form of a plate and the induction coil is mounted on a lower surface thereof so that the upper portion of the induction coil is sealed by the magnetic core and only the lower portion is in the direction of the semiconductor film. Or is exposed to, or Vertically And an induction coil wound around the middle thereof, the current applied to the induction coil forms an amplified induction magnetic field in the magnetic core, which in turn is applied perpendicularly to the semiconductor film from one end by turning the magnetic core. Or a structure in which a uniform magnetic flux is applied to the semiconductor film in a vertical direction by forming a magnetic flux distribution entering the other end, or Vertically And the induction coil wound around its left vertical portion, the current applied to the induction coil forms an amplified induction magnetic field in the magnetic core, which induces a magnetic field from the upper end to the lower end of the right vertical portion in which the middle part is separated. (Or from the lower end to the upper end), so that all of the magnetic flux is applied to the semiconductor film in exactly the vertical direction. 6. The apparatus according to claim 5, wherein in the third structure, a plurality of non-conductive substrates are mounted in a charging cassette made of AlN or quartz and thermally treated while continuously moving through the spaced intermediate portions of the right vertical portion. In heat-treating a semiconductor film on a non-conductive substrate having poor thermal stability, an alternating magnetic field from an induction coil while heating the semiconductor film by a heating apparatus to a temperature at which the semiconductor film can be inductively heated without damaging or deforming the non-conductive substrate. And heat treating the semiconductor film by causing it to be concentrated on the semiconductor film by the magnetic core. 8. The method of claim 7, wherein when the semiconductor film on the nonconductive substrate is a silicon film on a glass substrate, the heating temperature by the heating plate is in the range of 200 to 500 ° C. 9. The method according to claim 8, wherein the frequency of the stirring magnetic flux is 10 Hz to 10 MHz. 9. The method of claim 8, wherein the silicon film is an amorphous silicon film deposited on a glass substrate, and is crystallized by heat treatment, and when the P-type or N-type dopant is an ion implanted polycrystalline silicon film, it is activated by heat treatment. Way. The method of claim 10, wherein the crystallization of amorphous silicon is any one of solid phase crystallization, metal induced crystallization, or metal induced side crystallization. In heat-treating a conductor film on a non-conductive substrate having poor thermal stability, the alternating magnetic field from the induction coil is applied intensively on the semiconductor film by a magnetic core, thereby inducing heating the conductor film without damaging or deforming the non-conductive substrate. Heat-treating the method.