KR20060010959A - Method and system for catalytic metal doping for low temperature poly si(ltps) crystallization - Google Patents

Abstract

The present invention relates to a metal catalyst doping apparatus and doping method for silicon low temperature crystallization capable of depositing up to 10 ¹² atoms per unit area (cm 2) on a large area substrate.

The present invention includes a sputter gun configured for a special purpose, a plasma reflector, a sputtering method, a plasma control, and the like, and a doping that can secure a high yield and reproducibility of a product by minimizing sputtering yield with stability and reproducibility. An apparatus and a doping method are provided.

The doping apparatus and doping method provided by the present invention can be used to sputter the metal catalyst material in a low yield sputtering method, to set the placement of the substrate and the target vertically, and to adjust the degree of doping of the metal catalyst. It is characterized by adopting the doping method.

Sputtering, Metal Catalyst Doping, Silicon Low Temperature Crystallization

Description

Metal catalyst doping apparatus and doping method for silicon low temperature crystallization {Method and system for catalytic metal doping for low temperature poly Si (LTPS) crystallization}             

1 is a schematic diagram showing an electric field line existing between two electrodes

2 is a schematic view showing the configuration of a typical sputtering apparatus

3 is a schematic diagram showing what happens when cations in the plasma rush to the target surface

Figure 4 is a schematic diagram showing the principle of the metal catalyst doping apparatus according to the present invention

5 is a plan view and a side view showing the main portion of the metal catalyst doping apparatus according to the present invention;

6A and 6B are front and side cross-sectional views showing the overall configuration of the metal catalyst doping apparatus according to the present invention.

Figure 7 is a schematic diagram showing the mass production equipment of the cluster tool method applying the metal catalyst doping apparatus of the present invention

<Explanation of symbols for main parts of drawing>

10: sputter gun 11: reflector

12 target 13 plasma

14 substrate 15 support

16 gate 17 body

18: substrate support 19: lift

20: hinge 21: facing plate

22: preparation area 23: doping area

24: stop area 25: plasma sensor

26: vacuum pump 27: upper door

28: lower door 29: door support

30: vacuum robot 31: loading chamber

32: unloading chamber 33: control device

34: corrugated pipe 35: ball screw

36: motor 37: guide bar

38: linear bearing 39: straight rod

40: connector

The present invention relates to a metal catalyst doping apparatus and a doping method for silicon low temperature crystallization, more specifically, to adopt a low yield (split sputtering) method and newly configured the shape of the sputter gun to the metal for crystallization of amorphous silicon thin film The doping of the catalyst can be carried out uniformly and effectively, and particularly relates to a metal catalyst doping apparatus and doping method for silicon low temperature crystallization that can ensure the reproducibility and stability of the silicon low temperature crystallization process.

Since the suggestion of the use of TFT as a display switch device by Weimer in 1966, many scientists' efforts have reached the level of practical use by applying it to a wide range of fields including home appliances, computers and communication systems.

In the early flat panel display, a magnetic liquid crystal was used. Later, various materials were proposed and developed, such as CdSe and amorphous silicon.

A flat panel display using amorphous silicon is not only capable of large area deposition, but also has excellent uniformity over area, reproducibility between processes, and low temperature deposition so that polymer or glass can be used as a substrate. It is widely adopted.

However, in order to use polymer or glass as a substrate, shortening the temperature and time for crystallization is considered to be very important because all the heat treatment processes of the TFT fabrication process must be performed below the temperature at which deformation occurs in the glass.

In the case of active matrix OLED, low temperature crystallization process (LTPS) TFT technology is emerging as a combination of thin film transistor (TFT) to OLED.

Recently, mass-produced crystallization methods for producing low temperature poly-Si TFT flat panel displays have been variously attempted, and a method of heating a substrate to be heated in a furnace having a large space and a high energy excimer laser beam are used. The ELA method which scans and heats on a board | substrate is known as a typical method.

Since the phase transition temperature at which the crystallization occurs in the amorphous silicon is over 700 ° C, glass or polymer, which is used for most substrate materials, becomes unacceptable.

Therefore, silicon must be crystallized by injecting heat at a temperature lower than the temperature at which the phase change of the substrate material occurs, and a metal catalyst is mainly used for this purpose.

The sputtering method is mainly applied to put the metal catalyst on the surface of the amorphous silicon. In general, crystallization is easily performed because the amount of the injected metal catalyst is about 10 ¹⁵ atom / ㎠, but the grain size of the polysilicon (grain size has a very small disadvantage.

Therefore, it is most important that the metal catalyst injected on the amorphous silicon surface be uniformly and stably injected with the number of doped regions (10 ¹² atom / cm 2 or less) while reducing the amount as much as possible.

Some published patents also seek to reduce the number of metal catalysts entering the substrate by installing a mesh or pipe cell block between the target and the substrate, but these intermediate shields are sputtered and accumulated therein. As a result, numerous impurities are introduced into the substrate, which is not a desirable solution.

Accordingly, the present invention has been devised in view of the above, and by adopting a special type of sputtering method, a metal catalyst such as nickel can be injected in a very small amount (10 ¹² atom / cm 2) onto an amorphous silicon surface, and TFT -It can be applied not only to the display area such as LCD or active OLED, but also to the solar cell field, and to ensure the quality improvement and reproducibility of the product at the source, and to apply the low temperature crystallization of silicon that can be directly applied to industrial mass production line An object of the present invention is to provide a metal catalyst doping apparatus and a doping method.

In general, there are two methods of thinning a material, a physical method and a chemical method.

The dual physical method has the advantage that the process is relatively simple and high purity materials can be obtained.

Most processes require a high deposition rate, ie, the thickness of the material accumulation per unit time when the material is grown on a substrate as a thin film.

The same applies to the sputtering method.

In order to quickly grow a desired thin film with good properties using sputtering, the temperature of the substrate, the applied power, the distance between the substrate and the target, and the pressure of the gas in the vessel must be optimized.

However, the field to which the present invention is applied does not require a high deposition rate because it is intended to apply very little metal material to the catalyst.

Therefore, the present invention is to specially manufacture the sputter method, one of the thin film processing equipment, to inject a very small amount of the doped region into the desired amount of material rather than thinning.

In the doping method of the present invention, the sputtering target material that can be applied as a metal catalyst includes one of nickel, platinum, titanium and the like, or an alloy material thereof.

Among these, metals such as aluminum, gold, and silver form a metastable silicide phase due to silicon diffusion at the silicon interface, and the silicide lowers the crystallization energy and promotes the crystallization of silicon, whereas nickel and titanium Such metals dominate the diffusion of metals by heat treatment, and form silicide phases due to metal diffusion in the direction of the silicon layer at the interface between these metals and silicon, and these silicides promote crystallization to lower the crystallization temperature.

In addition, metal induced crystallization with nickel promotes crystallization by acting as the crystallization nucleus of NiSi ₂ , the final phase of nickel silicide.

The present invention for achieving the above object is characterized by a silicon low temperature crystallized metal catalyst doping apparatus and doping method, that is, a doping apparatus and method using a sputtering method.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

As shown in Fig. 1, the electric force lines formed between two electrodes are shown here.

When a potential difference occurs in parallel electrodes, an electric force line 120 having a uniform shape is generated between the two electrodes 100 and 110. When one of the electrodes 100 becomes smaller in a dot form, the electric force line 120 that is uniform is Will be collected in one direction.

Therefore, as can be seen in this case, it can be seen that the density of the electric field lines of the smaller electrode is larger.

As shown in FIG. 2, a sputtering apparatus using the principle between the electrode and the electric line of force is schematically shown here.

The negative electrode is connected to the sputter target 130, and the rest of the vacuum container 140, the gun shield 150, and the substrate 160 are all connected to the ground (0 V, relative anode).

Therefore, an electric field exists between the sputter target 130 which is a cathode and other parts except for this, and since the density of the electric field is maximum at the front of the sputter target 130, the plasma is evenly distributed in the vacuum chamber. Rather, it is generated intensively near the sputter target 130, which is the cathode.

This can be explained by the relationship of V '/ V = {A' / A} ⁴ , where A and A 'represent the areas of the two electrodes, and V and V' represent the potentials of the electrodes at both ends. .

Here, reference numeral 170 denotes a plasma region generated due to a high electric field density, and 180 denotes a traveling direction of the sputtered material.

FIG. 3 shows three phenomena that occur on the target surface when positive ions in the plasma thus generated rush toward the target, which is the cathode.

(a) is a chemical reaction phenomenon that shows that ions can react with other gas molecules or materials on the surface when they reach near the surface of the target, and (b) is a Sputtering is a phenomenon in which target materials are thrown out by dynamic energy, and (c) is an ion implantation phenomenon in which incident ions penetrate between substrate materials.

The above phenomena are always happening, and the process content is determined only by what causes the most phenomenon.

The sputtering device is a device that causes a large number of phenomena such as (b) among these phenomena.

Here, reference numeral 190 denotes incident ions, 200 denotes a target material, and 210 denotes a substrate material.

4 shows a concept of an off-axis doping apparatus using a sputtering method.

Since the doping apparatus has a purpose of using a target material as a doping material, a high deposition rate is not desirable.

Therefore, in the present invention, the deposition rate can be reduced to 1/10 or less compared to the on-axis sputtering method without applying a general on-axis sputtering method in which the target surface and the substrate surface face each other in order to lower the deposition rate. The off-axis sputtering method was applied.

The doping apparatus provided in the present invention basically includes a reflector plate 11 made of stainless steel in front of the sputter gun 10 in order to control the deposition rate.

The reflecting plate 11 can adjust the angle up to 45 ° counterclockwise in a parallel state facing the target surface, so that the plasma 14 generated in the vicinity of the target 12 is in the direction in which the substrate 14 is located. It can play a role of collecting and pushing.

Preferred target materials use catalyst metal materials such as nickel, platinum, titanium and the like.

Most sputter guns are in the form of magnetron sputter guns with strong magnets in the sputter gun as a way to increase the deposition rate.

The electrons in the plasma are driven by the Lorentz force by the magnetic field and revolve around the target, resulting in a significant improvement in the plasma density. Therefore, the magnetron gun type must be applied in the general process requiring high deposition rate.

However, in the present invention, since it is sufficient to obtain a deposition rate of the doping degree, a sputter gun (non magnetron) type without a magnet is used, and no separate coolant is supplied.

5 is a plan view and a side view showing the main portion of the metal catalyst doping apparatus according to the present invention.

As shown in FIG. 5, the process of spraying a sputter gun onto a substrate on which amorphous silicon is deposited shows a process of spraying a metal catalyst material onto the substrate.

Plasma 13 is formed between the target 12 mounted on the sputter gun 10 and the reflecting plate 11 maintaining a constant distance therefrom, and the entire sputter gun 10 including these is formed on the substrate 14. The metal catalyst is doped on the amorphous silicon thin film deposited on the substrate 14 while transferring the upper portion of the.

At this time, it is possible to obtain the effect of controlling the degree of doping in accordance with the feed rate of the sputter gun (10).

Here, when the size of the substrate 14 is 370 x 470 mm is applied, the size of the target 12 is preferably about 40 x 550 x 10 mm.

The amount of plasma 13 directed to the substrate 14 can be controlled by adjusting the direction, that is, the angle, of the reflecting plate 11 mentioned in FIG. 4.

To this end, the reflecting plate 11 is mounted in a rotatable structure through pin fastening while being supported at both ends between two supporters 15 extending from the sputter gun 10, and thus can be easily turned in a desired direction.

In addition, the motor 36 and the ball screw 35 are responsible for the transfer of the sputter gun 10.

That is, a vacuum linear bearing 38 is attached to the hem end of the sputter gun 10, and the linear bearing 38 is along two guide bars 37 fixed side by side on the main body 17. It is supposed to slide.

In addition, a ball screw 35 connected to the shaft of the motor 36 and a connecting body (not shown) extending from the body of the sputter gun 10 are screwed to transfer the sputter gun 10. When the motor 36 is operated, the sputter gun 10 can be transferred while the rotational motion is converted to the linear motion by the ball screw 35.

In addition to the method of positioning the ball screw inside the vacuum it can be applied to the method of positioning outside, which will be described in detail later.

6A and 6B are front and side cross-sectional views showing the overall configuration of the metal catalyst doping apparatus according to the present invention.

As shown in Figs. 6A and 6B, the substrate 14, which enters the inside of the main body 17 through the gate 16 of the rear portion, is placed on the substrate support 18, and then continues to operate the lift 19. Accordingly, it is lifted in one direction together with the substrate support 18 that rotates about the hinge 20 to reach the position of the opposing plate 21 and is fixed at the same time.

As described above, the substrate 14 is held vertically and fixed while being parallel to the counter plate 21 in the main body 17, thereby minimizing the inflow of impurities that may occur during the doping process.

The sputter gun 10 including the target material is disposed on the front surface of the substrate 14 to be transported along the surface of the substrate.

The working area of the sputter gun 10 is composed of three stage areas of the preparation area 22, the doping area 23, and the stop area 24 according to the feeding distance.

The preparation region 22 refers to a region where the plasma is first floated for doping and the sputter gun 10 waits until the process condition is confirmed. The stop area 24 is a return point for returning the doped sputter gun 10 to its original position.

At this time, the plasma state may or may not exist depending on the degree of doping required in the process.

When the sputter gun 10 transfers and the doping proceeds, a target feed rate control device using a motor is provided such that acceleration occurs in the preparation region, constant velocity in the doping region, and deceleration in the stop region.

When a predetermined basic vacuum of 5 × 10 ⁻⁶ Torr or less is reached, argon gas is injected to generate pressure of 5 to 20 mTorr in the main body 17 to generate a plasma.

Maintaining a constant state of the generated plasma at all times is very important for the reproducibility and uniformity of the doping process.

Therefore, in the present invention, the plasma sensor 25 is fixed in the plasma region of the preparation region 22 so that the predetermined plasma density state can be always confirmed.

The desired plasma density value is input to the plasma controller (e.g., the input value is referred to as "x"), and the measured plasma density is within a range of the allowable value of the input value (e.g., -a &lt; x &lt; + a). The sputter gun 10 transfer motor 36 to be driven only when it is detected.

Here, since the sputter gun to which the configuration of the present invention is applied must be driven in a vacuum environment, a low vacuum and a high vacuum pump 26 are used to exhaust the gas in the main body 17, thereby solving a trouble inside the doping apparatus. The upper doors 27 and the lower doors 28 were installed to facilitate the doors, and these doors were vacuum sealed with the door support 29.

In addition, the substrate support 18 has a heater or a heating wire therein to allow the substrate to be heated to 400 ° C. or less while metal doping is performed.

In addition, the lift 19 serves to lift the substrate support 18 by using a mechanism such as air pressure or a linear motor. In another embodiment, the lift 19 replaces the motor with a hinge portion of the substrate support 18 in place of the lift. It is possible to apply the way to install the rotary motion.

In the present invention, a method of lifting the substrate support 18 by a set angle using a pneumatic cylinder was applied.

For example, when the pneumatic cylinder is operated, the lift 19 rises and pushes up the bottom of the substrate support 18 to the plate at the upper end thereof, so that the substrate support 18 is rotated about the hinge portion to the vertical. It can be stood, and can be fixed while contacting the opposing plate (21).

In addition, the present invention provides another embodiment of the transfer method of the sputter gun (10).

To this end, both ends of the sputter gun 10 are supported by guide bars 37 arranged side by side in a space where doping is performed, and a straight rod 39 is long connected to the rear portion of the sputter gun 10. The connector 40 at the rear end of the straight rod 39 is screw-coupled to the ball screw 35 parallel to the straight rod 39, so that the straight rod 39 moves with the operation of the motor 36 and the sputter gun 10 can be transferred from the preparation region to the stop region through the doping region.

In order to maintain the vacuum, the periphery of the straight rod 39 is surrounded by a corrugated pipe 34 that can be folded or unfolded while being fixed to both ends of the body 17 and the connecting body 40, respectively.

In addition, since the strength of the electric field formed between the electrodes at both ends of the counter plate 21 is proportional to the voltage applied to both ends, the counter plate 21 satisfies E = V / d inversely proportional to the distance between the electrodes at both ends. In the doping apparatus of the present invention, which requires a constant plasma density, the doping apparatus is made of a metal conductor that can serve as an electrode at the same position as the substrate.

7 shows an example of a preferred mass production cluster tool to which the doping apparatus provided by the present invention is applied.

As shown in FIG. 7, a plurality of main bodies 17 including a loading chamber 31 and an unloading chamber 32 and a sputter gun for a doping operation are disposed radially with the vacuum robot 30 at the center thereof. Therefore, the substrates mounted on the loading chamber 31 are sequentially moved to each doping process, that is, the main body 17 by the vacuum robot 30, and then the process of being placed in the unloading chamber 32 after the doping process is performed. It can be performed sequentially.

Here, reference numeral 33 denotes a control device for electronically controlling these radial process equipment.

As described above, the metal catalyst doping apparatus and doping method for silicon low temperature crystallization provided in the present invention have the following effects.

① In the field of AM OLED manufacturing process, it is possible to effectively dop the metal material which acts as a catalyst in changing the amorphous silicon thin film deposited on the surface of the polymer or glass needed for TFT LCD or solar cell manufacturing process into polycrystalline. It works.

② The sputter gun is transferred to the substrate surface at the same speed and sputtering is performed for doping, so it is possible to expect a uniform doping.

③ Because the sputter gun checks the plasma state in the preparation area and performs the doping operation, it is effective to prevent the instability of the degree of doping.

④ It is effective to secure the reproducibility and stability in the low temperature silicon crystallization process, which is the biggest bottleneck in the flat panel display manufacturing process.

Claims (15)

In a method of doping a metal catalyst using a sputtering method during silicon low temperature crystallization, the sputtering method uses an off-axis sputtering method in which a metal catalyst doping is performed by vertically positioning a substrate surface and a target surface. A metal catalyst doping method for silicon low temperature crystallization characterized by. The method of claim 1, wherein the sputtering for the metal catalyst doping metal catalyst doping method for silicon low temperature crystallization, characterized in that by placing a reflecting plate parallel to the target surface between the substrate surface and the target surface to adjust the metal catalyst doping degree . The method of claim 2, wherein the doping of the metal catalyst using the reflector is a metal catalyst doping method for crystallization of silicon low temperature, characterized in that performed by adjusting the angle of the reflector. The method of claim 1, wherein the sputtering method for doping the metal catalyst is a method of doping the metal catalyst for silicon low temperature crystallization, characterized in that the doping of the metal catalyst while the sputter target is transported on the substrate surface in order to control the low metal catalyst doping degree Way. 5. The method of claim 4, wherein the sputter target is transported in three stages: a preparation region, a doping region, and a stop region. 6. The metal catalyst doping for silicon low temperature crystallization according to claim 4 or 5, wherein the transfer of the sputter target is controlled such that acceleration in the preparation region, constant velocity in the doping region, and deceleration in the stop region occur. Way. The silicon low temperature crystallization of claim 4 or 5, wherein the sputtering method generates a plasma in a preparation region before transfer of the sputter target so that the plasma state can be checked by a plasma density detecting means before the metal catalyst material is doped. Metal catalyst doping method for. A metal catalyst doping apparatus for silicon low temperature crystallization, A main body 17 having a space in which the substrate is allowed to enter and a vacuum is formed, and a hinged substrate support 18 and a lift 19 to lift and raise the substrate positioned inside the main body 17 in one direction. ), A counter plate 21 for fixing and maintaining the upright position of the substrate, and a sputter gun 10 positioned perpendicular to the substrate and carrying a metal catalyst material while transferring on the substrate surface. A metal catalyst doping apparatus for silicon low temperature crystallization, characterized in that. The method according to claim 8, wherein the sputter gun 10 is disposed between the substrate surface and the target surface in parallel with the target surface and the silicon plate for the low temperature crystallization, characterized in that for controlling the metal catalyst doping degree Metal catalyst doping apparatus. The metal catalyst doping apparatus for silicon low temperature crystallization according to claim 8 or 9, wherein the reflector plate (11) of the sputter gun (10) has an angle adjustable structure. The method of claim 8, wherein the sputter gun (10) is a metal catalyst doping apparatus for low temperature crystallization of silicon, characterized in that the transfer is divided into three stages of the preparation region, the doping region, the stop region. The apparatus for transporting the sputter gun (10) is provided with two guide bars (37) for slidingly supporting both ends of the sputter gun (10) in the doping region and the sputter gun (10). A straight rod 39 long connected to the rear portion and a connector 40 at the rear end for screwing, a corrugated pipe 34 surrounding the periphery of the straight rod 39 for maintaining the vacuum, and located outside the doping region Metal catalyst doping apparatus for low temperature crystallization of silicon, characterized in that consisting of a screw (35) and a motor (36) screwed to the connector (40) of the straight rod (39). 9. The metal catalyst doping apparatus for silicon low temperature crystallization according to claim 8, wherein the substrate support (18) is made of a heating plate in which a heater or a heating wire is embedded. 9. The doping apparatus for silicon low temperature crystallization according to claim 8, wherein the opposing plate (21) is made of a metal conductor that can serve as an electrode for a constant plasma density. The method according to claim 8, wherein the body 17 including the sputter gun 10 is a plurality of the radially disposed with the vacuum chamber 30 and the loading chamber 31 and the unloading chamber 32 in the center of the vacuum robot ( 30. A metal catalyst doping apparatus for low temperature crystallization of silicon, characterized in that the sequential doping process according to 30) can be performed.

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