KR101140750B1 - In-line Manufacturing Methods of Curved Surface F-dopped Tin oxide film - Google Patents

Abstract

The present invention relates to a coating system for forming an FTO transparent conductive film on a transparent substrate having a complex shape such as a curved surface. In particular, a pretreatment chamber, a deposition chamber, and a post-treatment chamber are linearly connected, and one side portion of the deposition chamber is provided. The FTO precursor is sprayed from the curved nozzle provided in the nozzle and the FTO thin film is deposited through a susceptor having a curved surface, and the FTO precursor flow flows in parallel with the substrate by suction on the opposite side. A curved FTO coating system allows uniform application of FTO.

Description

In-line Manufacturing Methods of Curved Surface F-dopped Tin Oxide Film

The present invention is a high-quality curved FTO (F-doped) by linearly connecting the pretreatment chamber, the deposition chamber, and the post-treatment chamber and sending a glass substrate having a complicated shape such as a curved surface to the pretreatment chamber, the deposition chamber, and the post-treatment chamber. Tin Oxide) is characterized by a system for manufacturing a substrate.

Recently, F-doped Tin Oxide (FTO) thin film material is emerging as an important material for solar cell core electrode material and IT field. The reason is that the FTO thin film material is transparent and conductive, but also has high temperature heat resistance (about 500 degrees) and excellent chemical resistance / corrosion resistance, which are distinguished from other transparent conductive films.

FTO manufacturing process technology is based on ultrasonic spraying and liquid spray spraying methods, in which the liquid FTO precursor solution is vaporized and vaporized onto a heated substrate, which looks similar to conventional chemical vapor deposition (CVD) technology. However, the transport of very large droplets (or atomized precursor droplets) ranging from several microns to hundreds of microns requires considerable understanding and equipment skills.

This is evident when comparing the diffusion and cohesion of micron droplets and CVD precursors consisting of ordinary single molecules. In terms of diffusivity, micron droplets are very slow to move and require a separate carrier gas. On the cohesive side, micron droplets have a very high cohesiveness, which means that the droplets no longer grow in the event of a gas or wall collision. In addition, a large amount of solvent and reaction gas are generated by the micron droplets as by-products during the reaction, and fine mist occurs on the surface of the substrate when the thin film is formed.

 In addition, in the conventional technology, a method of spraying mist onto the lower substrate through a nozzle of an upper layer is used, but problems of tropical flow of the mist and cooling of the thin film are seriously generated.

Therefore, the atmospheric pressure CVD method for spraying mist droplets has become an important technique in the configuration of the micron droplet introduction portion and the exhaust portion (FTO precursor flow control method). However, the production of FTO thin films by spraying mist droplets is generally very difficult and is currently being produced in small quantities by a limited number of companies, and the technologies are limited to FTO-containing applications. Representative examples include solar cell manufacturing technology (silicon solar cell, dye-sensitized solar cell), sensor application technology, and touch panel technology.

On the other hand, instead of the FTO equipment system, a number of element technologies are known, and typically, an apparatus having a cylindrical hood between an upper nozzle and a lower substrate (JP 2004-167394A), a source apparatus for generating a precursor (JP 2006-236602A), An apparatus for moving and coating a plurality of nozzles (JP 2003-205235A), a substrate immobilization apparatus (JP 2006-184341A), and a substrate strain suppression system (JP 2006-19135A) when using a large substrate.

The pretreatment chamber is responsible for pretreatment of the substrate. The pretreatment chamber is transferred to the deposition chamber by performing preheating, plasma surface cleaning, and barrier film coating.

In the deposition chamber, a curved nozzle part and an exhaust part are separately attached to the side, and an atomized FTO precursor is supplied to the side part and deposited on a glass substrate transported from the pretreatment chamber, and reactant gas, carrier gas, unreacted material, etc. Exits through the exhaust attached to the side opposite the nozzle.

The FTO-coated substrates transported to the aftertreatment chamber finally yield various FTO substrates through natural or functional cooling (FTO surface property conversion, tempered glass production, etc.).

The most important technique is to allow the FTO precursor droplets to flow in parallel with the substrate through the interdependence (spray-suction) relationship between the curved nozzle portion and the exhaust portion attached to the side surface of the deposition chamber. In addition, by placing the curved glass substrate on the susceptor of the curved surface to maintain a uniform temperature of the substrate to enable a uniform coating. Therefore, the FTO deposition conditions may be variously changed according to the spray amount, the exhaust amount, and the suction amount.

As described above, according to the present invention, the FTO substrate can be mass-produced through simple processes on a curved substrate which is continuously supplied by simply connecting the chambers and positioning the curved nozzle portion / exhaust portion at the side of the deposition chamber. Can be.

1 is a schematic illustration of a coating system according to the prior art, with nozzles installed on top perpendicular to the substrate;
2 is a schematic view of a curved FTO continuous coating apparatus according to the present invention.
3 is a perspective view of two types of representative curved nozzles according to the present invention;
4 is a schematic view of an apparatus comprising two or more curved nozzle portions or exhaust portions in accordance with the present invention;
5 is a schematic view of the inline device of the present invention in which two or more curved nozzle portions or exhaust portions in accordance with the present invention are constructed;
6 is a schematic view of an inline device comprising two or more curved nozzles or exhausts in accordance with the present invention;
7 is a graph showing the sheet resistance of the curved FTO thin film to the spray amount.
8 is a real digital photograph and sheet resistance of the curved FTO transparent thin film according to various spray conditions.
9 is a scanning electron micrograph (SEM) photograph of a cross section of a curved FTO thin film according to substrate temperature.
10 is a sheet resistance comparison of the curved FTO film with or without the barrier film in the pretreatment chamber.
11 is a result table for the post-treatment process of the present invention.
12 is a SEM image of mist generation and film uniformity according to curved nozzle positions (upper and side portions).
Fig. 13 is a comparison diagram of changes in FTO curved resistance when the curved FTO coating apparatus is not utilized.

In figure 2 a curved FTO coating system according to the invention is shown.

The curved substrate 2 introduced into the pretreatment chamber 1 may be surface treated or heated. That is, a heater (not shown in the drawing: a plate heater or a hot wall heater) and a plasma surface treatment agent (not shown) may be separately provided. The curved substrate thus pretreated is transported to the deposition chamber 3.

At this time, through the shutter or the air curtain (4) provided between the chamber between the chamber is closed and closed. The deposition chamber may separately have a heating system (not shown: plate heater or hot wall heater) or may be provided with a heater that rotates as shown in FIG. 5. As the heater rotates, the substrate on top also rotates, which makes the curved FTO coating uniform. One side portion of the deposition chamber 3 is provided with a curved nozzle portion 8 and a precursor flow 9 supplied from an external precursor source portion 7 is provided through the curved nozzle portion 8. It enters into the deposition chamber 3.

At this time, the movement of the precursor flow can be easily adjusted by the curved exhaust portion 10 provided on the opposite side portion. The curved exhaust portion 10 may also react with the reaction product gas, which is released from the deposition chamber. It is also responsible for the exhaust of the reaction gas, the carrier gas 9 and the like.

The curved FTO coated substrate 12 manufactured in the deposition chamber 3 is transferred to the aftertreatment chamber 11 through the shutter 4. The aftertreatment chamber 4 may be separately provided with a device of a heater (not shown in the drawing: a plate heater or a hot wall heater), a cooling device, a quenching device (such as tempered glass or FTO substrate surface morphology change).

The substrate of the present invention mainly means a glass substrate, but includes a material having corrosion resistance in hydrofluoric acid (this reaction generates hydrofluoric acid). In addition, the substrate of the present invention may include a state in which a barrier film is coated on a glass substrate.

The substrate of the present invention includes a state in which a multilayer film is coated on a glass substrate in advance through an optical design. Accordingly, the present invention provides equipment and processing techniques for coating FTO by flowing FTO precursor droplets parallel to the ground (same as the curved axis of the substrate) on the curved substrate.

3 illustrates two types of curved nozzles used in the present invention. The curved nozzle portion 8 of FIG. 2 (a) has a precursor outlet portion 81 which opens in a linear manner so that the precursor flow 9 can easily flow into the deposition chamber.

In FIG. 3 (b), a portion through which the precursor flow 9 exits is formed as a hole 81, and these holes are formed in a curved linear form or a curved multilayered linear form. In the case of the hole type, pressure is generated inside the nozzle before the precursor exits, thereby enabling a larger area injection.

3 (c) shows the nozzle of the hole type actually used. The diameter of the hole is 3.5 mm and the total size of the nozzle is 500 mm x 10 mm. The space between holes is 5mm. However, the present invention is not limited to such hole diameters, hole spacing, and nozzle portion dimensions.

As such, the equipment of FIG. 2 may be equipped with two types of curved nozzles of FIG. 3. In addition, FIG. 2 may include two or more curved nozzle portions and an exhaust portion as shown in FIG. 4. In this case, curved nozzles and exhaust parts can be arranged in parallel (Fig. 4 (a)) or anti-parallel (Fig. 4 (b)).

Substrate transport can be transported through a robotic arm transport system or transported to each chamber via an inline transport system. Inter-chamber sealing can be achieved through shutters or gas curtains.

In particular, as shown in FIG. 5, the inline transport system is very advantageous when a plurality of curved nozzle portions and multiple curved exhaust portions are provided in parallel (FIG. 5A) or anti-parallel (FIG. 5B). In addition, the neglect of FIG. 5 may reduce the number of curved exhaust parts as shown in FIG. 6.

The curved FTO film is sprayed onto the heated glass substrate inside the deposition chamber 3 through the curved nozzle part 8 of FIG. 2 after spraying the precursor solution for FTO in the form of micro droplets by spray coating or ultrasonic spraying. Are manufactured.

The formation process of curved FTO thin film is Pyro-sol principle. Or it is easily explained by the principle of chemical vapor deposition (CVD).

Curved FTO precursor solution is prepared by dissolving SnCl ₄ 5H ₂ 0 in tertiary distilled water to 0.68 M, dissolving NH ₄ F as ethanol solvent to 1.2 M as a F dopant, mixing and stirring the two solutions, and filtering. It was. It is also possible to use only pure water as the solvent. It is also possible to use other alcohols.

In addition, in the present invention, in order to manufacture various curved FTO membranes, alcohols and ethylene glycol may be additionally added in addition to the solution composition. In order to control the amount of F doping, the amount of NH ₄ F was changed from 0.1 to 3 M, or 0-2 M of hydrofluoric acid (HF) was added. Therefore, the precursor solution for producing the curved FTO membrane is not limited to the composition shown above.

In general glass used as a curved substrate, when heated to 400-600 degrees, impurities such as Na and K diffuse onto the substrate and damage the surface of the glass substrate. This results in a decrease in film adhesion and film quality even when the FTO film is coated. Therefore, a barrier layer coating must be applied between the glass substrate and the FTO film to block impurities.

Generally, many ceramic films such as SiO ₂ and TiO ₂ are used, but in the present invention, SiO ₂ is typically represented. The barrier film is formed by using dip coating and spray coating at a thickness of about 5-50 nm. In the case of a small substrate, a dip coating method was used, and in the case of a large substrate and a curved substrate, a SiO ₂ barrier film was formed using a spray coating method.

In the dip coating method, silica sol [ethanol (95%): Tetraethyl silicate: Nitric acid = 90: 11: 0.5 (volume ratio)] was prepared, dip coated at a speed of 150 mm / min, and then heat-treated at 300-400 degrees for 5 minutes. SiO ₂ barrier film was formed. Spray coating was performed on large area substrates or curved glass substrates. Silane reagents (SiH ₄ , SiH ₂ Cl ₂ , Si (OC ₂ H ₅ ) ₂ , etc.) can be easily formed on the glass substrate heated to 400-600 degrees in air or in an oxygen atmosphere by using the CVD principle (spray). have. When using high quality glass, ie, when using a glass substrate with few impurities, such as Na and K (for example, borosilicate glass), it is not necessary to form a barrier film.

In order to atomize the FTO precursor in the gas phase to obtain the precursor flow 9 of FIG. 2, the precursor source 7 is separately connected with three apparatuses, a spray coating method, an ultrasonic spray coating method, and an ultrasonic spray spray method.

The three coating methods are well known methods, and the spray coating method is a method of spraying a liquid precursor into microdroplets due to the force of attracting a liquid when an external gas is expanded through a fine nozzle unit. Ultrasonic spraying is a method in which a liquid precursor is vibrated by an ultrasonic vibrator and atomized by a carrier gas, just like a general ultrasonic humidifier. Finally, the ultrasonic spray spraying method is to change the ultrasonic vibrator portion like a spray nozzle and spray the atomized precursor by spraying principle. The typical substrate temperature was 400-600 degrees, using a common pane with a SiO ₂ barrier film coated at 5-50 nm. The surface resistance of the thus-formed curved FTO film is about 4-7 Ω.

8 is a graph showing the sheet resistance of the curved FTO thin film to the spraying amount using one nozzle and one exhaust system of FIG. 1 when using one ultrasonic terminal (1.6HZ). Typically, 150 ml (4 Ω), 40 ml (56 Ω), 60 ml (26 Ω) and 70 ml (25 Ω).

7 shows the actual digital photograph and sheet resistance of the curved FTO transparent thin film according to various spray conditions.

9 is a cross-sectional SEM (scanning electron micrograph) photograph of the curved FTO thin film according to substrate temperature.

Fig. 10 shows the difference between the case of applying the barrier film on the curved glass substrate in the pretreatment chamber and the case of not applying the barrier film. FIG. 10 (a) shows the case where the barrier film is coated with 30-50 nm (see Example), and FIG. 10 (b) shows the case where the barrier film is not provided.

11 presents the results for the post-treatment process of the present invention. It is observed that the strength of the glass substrate is improved about 5-20% when nitrogen is injected per 0.1-10 ml / cm 2 min onto the heated FTO substrate and the lower heater portion is kept heated. In addition, the above effects can be obtained by spraying a liquid solvent (eg, water, ethanol, methanol) at 0.01-3 ml / cm 2 min.

12 (a, b) is a SEM schematic diagram in which fine mist occurs on the surface of the substrate when the curved nozzle is installed at the upper end, and FIG. 12 (c) shows the curved nozzle horizontally (side surface). In this case, it is a SEM photograph showing the characteristics of film uniformity and film properties by reducing large defects.

 When supplied horizontally, the homogeneity of the thin film and the uniformity of irregularities can be obtained by removing the unreacted mist from the hole or linear curved nozzle. Therefore, the data based on the device principle diagram of the present invention of FIGS. Shows.

Comparative Example 1

  1 is a schematic diagram of a system in which a feed nozzle of a raw material is installed on a vertical upper portion of a substrate. As the droplets of the solution sprayed from the nozzle installed on the upper reaches the lower heated substrate, the droplets undergo evaporation of the solvent, decomposition of organic matter, decomposition of bound water, formation of oxide clusters, and the like.

  At this time, droplets supplied on the substrate collide with each other in the space between the nozzle and the substrate, or micron-sized particles that partially react undesirably collide directly on the substrate and fall onto the substrate. Degree. 11 (a, b) is a SEM photograph of the case produced by spraying the FTO solution from the nozzles arranged in the vertical direction to the substrate. As shown in the photograph, the formation of a number of large particles is observed. Degree. 11 (c) is sprayed in the horizontal direction (side). SEM image obtained by removing unreacted mist from holes or linear nozzles to obtain uniformity of film and uniformity of irregularities.

Comparative Example 2

 12 is a measurement of the resistance change when the curved surface using the FTO transparent conductive film prepared on a plane, without utilizing the curved FTO coating apparatus facilities. The planar FTO transparent conductive film was curved at 500 ~ 600 ℃, similar to the softening point of glass, and the flat FTO transparent conductive film showing resistance characteristics of about 8Ω and 12Ω was used at 400 ℃, 500 ℃ and 600 ℃. The change in resistance characteristics is shown. The curved FTO transparent conductive film showed an increase in resistance of about 1.5 to 12% for an 8Ω substrate at a temperature of 500 ° C and 600 ° C, and a resistance characteristic change of 5.5 to 7.7% for a 12Ω substrate.

When the curved FTO coating apparatus is not utilized, the resistance value may be increased due to grain damage of the FTO transparent conductive film.

Claims (12)

delete delete delete In the curved continuous FTO thin film manufacturing apparatus,
A pretreatment chamber, a deposition chamber, and a post-treatment chamber are linearly provided, and a curved nozzle part is attached to one side of the deposition chamber, and a curved exhaust part is installed on a side opposite to the curved nozzle.
In the pretreatment chamber a curved substrate is pretreated and moved to a deposition chamber;
Forming a uniform curved FTO film by injecting the FTO precursor through the curved nozzle portion of one side of the deposition chamber and simultaneously flowing the FTO precursor in parallel with the substrate through suction of the exhaust portion,
The FTO-coated curved substrate is moved to a post-treatment chamber for post-treatment,
In the pretreatment chamber, plasma pretreatment of the curved substrate to move to the deposition chamber,
Curved continuous FTO thin film manufacturing method characterized in that the plurality of curved nozzle portion or the exhaust portion provided on the side portion of the deposition chamber. The method of claim 4, wherein in the pretreatment chamber, a barrier film is coated on the curved substrate to move to the deposition chamber. The method of claim 4, wherein in the deposition chamber, the FTO film is coated at a curved substrate temperature of 400-600 degrees. The method of claim 4, wherein in the deposition chamber, a curved substrate holder is rotated. The method for manufacturing a curved continuous FTO thin film according to claim 4, wherein in the post-treatment chamber, a gas is sprayed onto the FTO curved substrate to quench the substrate. The method of claim 4, wherein in the post-treatment chamber, a solvent is injected into the FTO to quench the curved substrate. The method for manufacturing a curved continuous FTO thin film according to claim 4, wherein the exit portion of the curved nozzle portion is bored into a linear space. The method for manufacturing a curved continuous FTO thin film according to claim 4, wherein the outlet portion of the curved nozzle portion is composed of a plurality of holes. The method of claim 4, wherein the FTO precursor is manufactured by any one of a spray coating method, an ultrasonic spray coating method, and an ultrasonic spray spraying method.

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