KR20010011182A - method of forming thin film - Google Patents

Abstract

PURPOSE: A method for fabricating a material layer is provided to form an amorphous thin film or polycrystalline thin film on a predetermined substrate, and to separate the amorphous thin film or the polycrystalline thin film for being transferred to another substrate. CONSTITUTION: A material layer(2) whose chemical characteristic is different from that of the first substrate is grown on the first substrate(1) to separate the material layer from the first substrate. The separated material layer is transferred to the surface of the second substrate. The transferred material layer is adhered to the second substrate.

Description

Material film manufacturing method {method of forming thin film}

The present invention relates to a method of manufacturing a material film, and more particularly, to a method of forming an amorphous or polycrystalline thin film on a predetermined substrate, and then separating and transferring the same to another substrate.

As a pixel driving switching element of a liquid crystal display (LCD), which is mainly used in the multimedia industry in recent years, a thin film transistor using a Si (silicon) film formed on a transparent insulating substrate as an active layer; , Referred to as TFT). In this case, the Si (silicon) thin film used as the active layer is called a-Si in the case of an amorphous thin film and p-Si in the case of a polycrystalline thin film. Currently, liquid crystal displays (LCDs) using insulated gate type TFTs made of amorphous silicon (a-Si) as pixel switches have been mass produced.

The TFT-LCD module is largely composed of three units. First, a panel in which liquid crystal is injected between two substrates between the substrate and the substrate. Second, a driving circuit unit including a driver for driving the panel and a printed circuit board (PCB) to which various circuit elements are attached. It contains the chassis structure. The TFT-LCD module is used as an auxiliary means for displaying functions in systems such as notebook computers, TVs and monitors.

In the manufacturing technology of a TFT substrate or a C / F (color filter) substrate, the process of forming a TFT-Array is similar to a silicon semiconductor manufacturing process. That is, it consists of processes such as thin film deposition, photolithography, etching, etc., and includes inspection for checking results and abnormalities before and after each process and cleaning for maintaining cleanliness. . The above unit processes are performed in a series of repeated processes to form each layer, and are closely related to the before and after processes. The difference from the silicon semiconductor process is that in semiconductor manufacturing, the silicon wafer is processed through a complicated process to make a device, but in the TFT-LCD manufacturing, the size of the LCD screen is determined, and the required screen size is increasing. Increasing the size of the substrate can increase the production quantity.

The TFT has three electrodes, a gate, a source and a drain. The TFT serves as a switch for applying a signal voltage to the pixel electrode. When a positive voltage is applied to the gate electrode, electrons are concentrated in the a-Si channel region by the field, and a conductive channel is formed to form a gap between the source and drain electrodes. Allow current to flow through. A TFT is a type of field effect transistor (FET) that regulates the flow of current by an electric field. TFT design is the most important factor in determining the image quality obtained by an LCD panel.

Color TFT-LCDs can be divided into amorphous TFT and polycrystalline TFT according to the type of TFT device. Among these, the LCD using an amorphous TFT is the most widely used. An important advantage of amorphous TFTs is that glass substrates can be used, unlike polycrystalline TFTs, because the substrate processing temperature is lower than 300-350 ° C in the manufacturing process.

Since the amorphous silicon (a-Si) film can be formed at a temperature of 400 ° C. or lower, it can be formed on a glass substrate. However, since the amorphous silicon thin film a-Si has a high resistivity value and contains many defects, it is difficult to realize a high-performance display such as high precision and high speed. That is, since the field mobility (μFE) of the amorphous silicon thin film transistor is lower than 1 cm ^ 2 / Vs, it is difficult to improve the performance of the thin film transistor. In order to further improve the performance of the thin film transistor, it is necessary to apply a polycrystalline silicon film having excellent crystallinity. However, while an amorphous silicon film is formed at a temperature of 400 ° C or lower, polycrystalline silicon film should be formed at a relatively high temperature of 600 ° C or higher. Therefore, since the substrate material for forming the same must use quartz or the like, the manufacturing cost increases.

An object of the present invention is to provide a manufacturing method for forming an amorphous or polycrystalline thin film.

Another object of the present invention is to provide a method for growing and separating an amorphous or polycrystalline thin film having different chemical properties on an amorphous, polycrystalline or single crystal substrate.

It is another object of the present invention to provide a method of forming a polycrystalline silicon thin film on a glass substrate at low temperature.

Another object of the present invention is to provide a method for producing a p-Si TFT.

A feature of the present invention for achieving the above object is to grow a material film having a different chemical property from the first substrate on the first substrate to separate the material film from the first substrate.

A detailed feature of the present invention includes separating the material film grown on the first substrate, transferring the separated material film onto the second substrate, and bonding the transferred material film to the second substrate.

Other detailed features of the present invention include transferring a first substrate on which a material film is grown onto a second substrate, bonding a first substrate on which the transferred material film is grown, to a second substrate, and a first substrate excluding the material film. It includes a process of separating on the second substrate.

1a to 1e is a view showing a manufacturing method according to an embodiment of the present invention,

2a to 2e is a view showing a manufacturing method according to an embodiment of the present invention.

Hereinafter, each embodiment of the present invention will be described with reference to the accompanying drawings.

1 shows a first embodiment according to the present invention. 1 a shows a first substrate 1. As shown in Fig. 1B, a material film 2 having a different chemical characteristic from that of the first substrate 1 is grown thereon. The first substrate 1 may include Al ₂ O ₃ (sapphire), CaF ₂ (calcium fluoride), NaCl (sodium chloride), CoSi ₂ (cobalt silicide), KCl (potassium chloride), KH ₂ PO ₄ (potassium dihydrogen). single crystals such as phosphate) and amorphous or polycrystalline materials may be used. The material film formed to have a predetermined thickness thereon includes Si (silicon), Ge (germanium) or GaAs (gallium arsenide) as the semiconductor, TiSi ₂ or CoSi ₂ as the metal silicide film, and Al (aluminium) or Cu as the metal thin film. As the dielectric thin film, Ta ₂ O ₅ , BST or PZT may be used.

In the following description, a case of using a single crystal as a first substrate will be described. As already mentioned, the first substrate may use a polycrystalline or amorphous material, and the first substrate may be formed thereon. Materials different in chemical properties from the substrate can be used.

In fabricating TFTs, thin film deposition is mainly performed by sputtering for metal films and transparent electrodes, and plasma enhanced chemical vapor deposition (PECVD) for silicon and insulating films.

The principle of sputtering is to inject Ar gas between a target made of a metal to be deposited with high voltage and an anode electrode, and to excite Ar ⁺ using plasma discharge, The accelerated Ar ⁺ can release atoms on the metal surface when the high kinetic energy is greater than the binding energy between the metal atoms. Sputtered atoms dissipate the energy they have through mutual collisions and interference and grow to form a thin film by bonding to each other on the surface of the glass substrate.

In general, magnetron sputtering, which is used for metal film deposition, uses DC plasma, and a magnetic field generated in a diode structure in which magnetic flux is installed prevents the excitation of Ar. Secondary electrons can be isolated to facilitate plasma adjustment to increase deposition efficiency.

The mechanism of chemical vapor deposition (PECVD) is that the electrons excited by the plasma collide with the gaseous compound introduced into the neutral state to decompose the gaseous compound, recombine with the help of the reaction between the formed gas ions and the thermal energy provided by the substrate. This is the principle of growth.

Embodiments of forming a thin film including the above method are as follows. First, the formation of a semiconductor thin film will be described. After preparing a silicon (Si) substrate as the first substrate 1, a source gas such as SiH ₄ , SiH ₂ Cl ₂ , SiHCl ₃ , SiCl ₄ containing silicon (Si), and H ₂ , Cl ₂ The silicon thin film is formed on the first substrate 1 by chemical vapor deposition (CVD) under an atmosphere of a mixture of reactive gases such as HCl, a temperature of 500 ° C. to 1200 ° C., and a pressure of 1 atm or less. Preferably, the silicon thin film is formed under a temperature of 600 ° C to 900 ° C and a pressure of 100 torr or less. In particular, when the PECVD method is applied, a method of vapor deposition at 300 to 450 ° C is included. In addition, using silicon (Si) as a target material, sputtering using a plasma discharge while maintaining argon or a vacuum containing argon and nitrogen, a pressure of 10 torr or less, and a substrate temperature of 600 ° C or less You may form a silicon thin film by sputtering.

Second, forming a metal thin film on the first substrate will be described. The difference from the process of forming the semiconductor thin film is that a metal thin film such as Al (aluminium) or Cu (copper) is formed on the first substrate 1 by sputtering or vapor deposition. The formation of the metal silicide film using TiSi ₂ , CoSi _2, etc. is also similar to the formation process of this metal thin film, and the other processes are the same as the formation process of the semiconductor thin film.

Next, the method of forming the dielectric thin film on the first substrate 1 is different from the process of forming the semiconductor thin film, in which Ta ₂ is formed on the first substrate 1 by sputtering or chemical vapor deposition (CVD). It forms a dielectric thin film 3 having a high dielectric constant such as tantalum pentaoxide (O ₅ ), barium strontium titanate (BST) or lead zirconate titanate (PZT). Others are the same as the process for forming the semiconductor thin film. The composition of the dielectric thin film is controlled so that the ratio of Ba and Sr is the same in the case of BST, and the ratio of Zr and Ti is 30-40: 70-60 in the case of PZT.

In addition, Ba (THD) ₂ , Sr (THD) ₂ , Ti (THD) ₂ (i-OC ₃ H ₇ ) _2, and the like are used to form a BST single crystal thin film by applying chemical vapor deposition (CVD) to THF (tetrahydrofuran). The thin film is formed by evaporation at 700 ° C. or lower using a liquid source diluted in the above). Here, THD represents C ₁₁ H ₁₉ O ₂ , THF represents C ₄ H ₈ O, and THD (tetramethyl heptane dionate) may be replaced with dipivaloylmethane (DPM). In addition, when the PZT single crystal thin film 3 is formed by applying the chemical vapor deposition method, a liquid source such as Pb (C ₂ H ₅ ) ₄ , Zr [OC (CH ₃ ) ₃ ] ₄ , Ti (OC ₃ H ₇ ) _4, or the like is used. Using to evaporate at 700 ℃ or less to form a thin film.

After separating the material film 2 from the first substrate 1 on which the material film 2 is formed as shown in FIG. 1C, the material film 2 is transferred onto the second substrate 3 as shown in FIG. After placing the material film 2 on the second substrate 3, the material film 2 and the second substrate are heat-bonded and bonded as shown in FIG. 1E.

2A to 2E illustrate another embodiment of the present invention. FIG. 2A shows the growth of the first substrate 1 and the growth of the material film 2 having different chemical properties on the first substrate 1. As shown in FIG. 2C, the material film 2 is transferred onto the second substrate 3 so as to face the second substrate 3 and bonded as shown in FIG. 2D.

Thereafter, the material film 3 is left as shown in FIG. 2E, and only the first substrate 1 is selectively removed. In this case, when the first substrate 1 is Al ₂ O _3, an etching gas containing NaOH solution or F (fluor) element is used, and if CaF ₂ , an etching gas containing acid solution or H element is used, NaCl is used. In the case of KCl or KH ₂ PO ₄ , the first substrate 1 is selectively selected by using a high solubility solution such as H ₂ O or an etching gas containing OH element, and using CoSi ₂ , using HCl solution or Cl or F element. To remove it.

In a p-Si TFT, a polycrystalline thin film such as silicon must be formed thereon using a material such as quartz as a substrate. However, when the present invention is applied, a polycrystalline TFT-LCD can be manufactured at low cost by bonding a polycrystalline thin film grown and separated on the first substrate thereon using a second substrate as glass.

In this embodiment, the first substrate is used as a single crystal material, but in the same manner as in the above embodiment, the first substrate may be replaced with an amorphous or polycrystalline substrate instead of a single crystal to form a polycrystalline or amorphous thin film. This thin film can be used separately from the first substrate.

As described above, when the polycrystalline or amorphous thin film is used in the thin film transistor, the polycrystalline or amorphous thin film transistor can be grown on another substrate, selectively separated, and used on the glass substrate, thereby manufacturing the polycrystalline or amorphous thin film transistor on the glass substrate. . In addition, to form a polycrystalline thin film transistor, an expensive material such as quartz is required as the substrate material. However, since the glass substrate can be used, the manufacturing cost of the polycrystalline thin film transistor can be reduced. In addition, in the case of the amorphous thin film, since the selection of the substrate is more diverse than the case of using the same substrate, it is advantageous because an amorphous thin film having excellent crystallinity can be utilized. In the above, the case of applying to a thin film transistor is taken as an example, but the polycrystalline or amorphous thin film grown / separated from a predetermined substrate is bonded to another substrate to have an effect that can be widely used as a device for manufacturing an electronic component.

Claims (11)

And growing a material film having a different chemical property from the first substrate on the first substrate to separate the material film from the first substrate. The method of claim 1; Separating the material film grown on the first substrate; Transferring the separated material film onto the second substrate; And a step of bonding the transferred material film to the second substrate. The method of claim 1; Transferring the first substrate on which the material film is grown onto a second substrate; Bonding the first substrate on which the transferred material film is grown to a second substrate, And separating the first substrate except the material layer on the second substrate. The method of any one of claims 1 to 3; And the material film is Si, Ge or GaAs as a semiconductor. The method of any one of claims 1 to 3; The material film is a material film manufacturing method, characterized in that the metal silicide film TiSi ₂ or CoSi ₂ . The method of any one of claims 1 to 3; And the material film is Al or Cu as a metal thin film. The method of any one of claims 1 to 3; The material film is a material film manufacturing method, characterized in that the Ta ₂ O ₅ , BST or PZT. The method of claim 1; And wherein the first substrate is a single crystalline, polycrystalline or amorphous material. The method of claim 1; And the material film is a polycrystalline or amorphous thin film. The method of claim 2; A method of manufacturing a material film, characterized in that a glass substrate is used as the second substrate. The method of claim 3; A method of manufacturing a material film, characterized in that a glass substrate is used as the second substrate.