WO2014027854A1

WO2014027854A1 - Method for forming dielectric layer using icvd

Info

Publication number: WO2014027854A1
Application number: PCT/KR2013/007375
Authority: WO
Inventors: 임성갑; 유승협; 성혜정; 문한얼; 김민철
Original assignee: 한국과학기술원
Priority date: 2012-08-17
Filing date: 2013-08-16
Publication date: 2014-02-20
Also published as: KR101401601B1; KR20140023114A

Abstract

The present invention relates to a method for forming a dielectric layer using iCVD. According to the present invention, the method for forming a dielectric layer on an organic thin film transistor using iCVD comprises the steps of: thermally decomposing an initiator by the heat injected on the organic thin film transistor to form free radicals; activating monomers by using the free radicals to form a polymer by chain polymerizing the monomers; and depositing the polymer on the organic thin film transistor to form a polymer dielectric layer. According to the present invention, it is possible to solve, through iCVD, a shortcoming of a narrow width of a dielectric layer prepared by PECVD or CVD, and carry out uniform deposition compared with a conventional process, and a very low leakage current is shown in various thickness, thereby having remarkable electrical properties through a high dielectric constant, and the manufacturing yield of a device is high. In addition, it is possible to prevent damage to a deposition medium due to a solvent since a desired polymer dielectric layer can be deposited with monomers and an initiator in a vapor phase condition without a solvent, particularly, an organic solvent.

Description

Insulating film formation method using iCDW process

The present invention relates to a method for forming an insulating film using an iCVD process, and more particularly, to an insulating film forming method using an iCVD process for forming an insulating film by using an initiated chemical vapor deposition method.

In general, a method of manufacturing an insulating film used for an organic thin film transistor is largely divided into a liquid phase process and a gas phase process. Liquid phase processes include spin coating, dip coating, and self-assembled monolayer (SAM). These methods require solvents to make insulating films. However, in the process of using the solvent, the metal electrode or organic material of the organic thin film transistor is damaged when the solvent occurs. In addition, annealing the device is required to remove the solvent, which is not only time-consuming but also results in decomposition of organic matter during annealing.

Here, a thin film transistor (TFT) is a switching element for controlling the operation of each pixel and each pixel in a flat panel display device such as a liquid crystal display (LCD) or an electroluminescence display device (ELD). It is used as a driving element of. In addition, thin film transistors are expected to be used in plastic chips for smart cards or inventory tags.

The thin film transistor has a semiconductor layer having a source region and a drain region doped with a high concentration of impurities and a channel region formed between the two regions, the gate electrode being insulated from the semiconductor layer and located in a region corresponding to the channel region. And a source electrode and a drain electrode in contact with the source region and the drain region, respectively.

Inorganic semiconductor materials such as silicon (Si) have been generally used as channel layers of thin film transistors, but organic semiconductors are used in inorganic materials requiring high price and high temperature vacuum processes due to the large size, low cost, and flexibility of displays. It's turning to matter. Therefore, research on organic thin film transistors (OTFTs) using an organic film as a semiconductor layer has been actively conducted.

Meanwhile, Korean Laid-Open Patent Publication No. 2006-0019868 discloses a technique related to a method of manufacturing an insulating film using a double organosiloxane precursor. Referring to FIG. 1, a mixture of a double organosiloxane precursor compound and a film property modifier may be prepared by depositing on a wafer using chemical vapor deposition, in particular PECVD. Furthermore, a compound having a specific structure, in particular, a double organosiloxane compound in which two silicon forms are contained in one molecule, and deposited on a wafer by PECVD method, has excellent mechanical properties such as elastic modulus and hardness. The present invention has been found to provide an insulating film including a semiconductor interlayer insulating film for dual damascene copper interconnects and a protective film for semiconductor and display devices with excellent thermal stability and crack resistance.

However, in the prior art, since the insulating film is manufactured by the PECVD method, organic materials are frequently damaged as in the liquid phase process because the process temperature of PECVD or CVD is very high, around 300-600 ° C. Moreover, the gas phase process requires high temperature and low vacuum, and thus has a problem of being evaluated as a poor process in terms of energy.

In addition, although not shown in the drawings, it is very difficult to develop a device using an insulating film having a uniform and thin thickness by an existing method by spin coating or PECVD. This is because the thickness of the polymer insulator made of spin coating is usually about 450 ~ 600nm, reducing the thickness to 100nm or less causes a problem that the yield of the device is significantly lowered during device fabrication.

An object of the present invention is to solve the shortcomings of the insulating film manufactured in the PECVD process or CVD process through the iCVD process, uniform deposition is possible than the existing process, and shows a very low leakage current even at various thicknesses An object of the present invention is to provide a method of forming an insulating film using an iCVD process, which has excellent electrical characteristics of the device and high yield of device manufacturing.

In order to achieve the above object, an insulating film forming method using an iCVD process according to the present invention includes a method of manufacturing an insulating film on an organic thin film transistor, wherein the initiator is thermally decomposed by heat injected onto the organic thin film transistor to free radicals. forming radicals; Chain polymerizing the monomer by activating the monomer using the free radicals to form a polymer polymer; And forming the polymer insulating layer by depositing the polymer polymer on the organic thin film transistor.

In addition, the polymer is any one of poly (cyclosiloxane), poly (perfluorodecylacrylate), poly (FMA), poly (IBA), poly (EGDMA), poly (V3D3), poly (PFDA) and poly (V3D3-PFDA copolymer) Can be applied.

In addition, when the polymer is poly (cyclosiloxane), the insulating film process conditions are the flow rate of the vapor (monomer: initiator) is 2.0 ~ 3.0: 0.5 ~ 1.5, the process pressure is 250 ~ 350mTorr, filament heating temperature is 200 ~ 300 It is degrees C, the glass substrate cooling temperature is 100 degrees C or less, and a process time may be 1-3 nm / min.

In addition, when the polymer is poly (perfluorodecylacrylate), the insulating film process conditions are the flow rate of the vapor (monomer: initiator) is 0.5 ~ 1.5: 0.5 ~ 1.5, the process pressure is 50 ~ 150mTorr, filament heating temperature is 150 ~ 250 ℃, the glass substrate cooling temperature is 100 ℃ or less, the process time may be 50 ~ 150nm / min.

According to the present invention, the narrow manufacturing width of the insulating film manufactured in the PECVD process or the CVD process can be eliminated through the iCVD process, and the deposition is more uniform than that of the existing process, and the insulation current is very high due to the very low leakage current even at various thicknesses. The rate is excellent in the electrical characteristics of the device, and the production yield of the device is effective.

In addition, the present invention can deposit the desired polymer insulating film with the monomer and the initiator in a gaseous condition without using a solvent, especially an organic solvent, there is an effect that can prevent damage to the deposition medium due to the solvent.

1 is a schematic diagram of an apparatus for manufacturing an insulating film using a double organosiloxane precursor compound according to the prior art.

2 is a process diagram of an insulating film forming method using an iCVD process according to an embodiment of the present invention.

FIG. 3 is a graph showing a correlation between a thickness of a polymer material poly (perfluorodecylacrylate) and a poly (cyclotrisiloxane) and a leakage current in an insulating film formed by an insulating film forming method using an iCVD process according to an embodiment of the present invention.

4 is a graph showing the correlation between the capacitance of the polymer materials poly (perfluorodecylacrylate) and poly (cyclotrisiloxane) and the frequency domain in the insulating film formed by the insulating film formation method using the iCVD process according to an embodiment of the present invention.

5 is a process diagram of manufacturing a fullerene thin film transistor using an insulating film formed by an insulating film forming method using an iCVD process according to an embodiment of the present invention.

6 is a graph showing the performance of the transistor through the transfer curve and the output curve in the fullerene (fullerene) thin film transistor manufactured by the insulating film manufactured by the insulating film forming method using an iCVD process according to an embodiment of the present invention.

The terms or words used in the present specification and claims are meant to be consistent with the technical spirit of the present invention on the basis of the principle that the inventor can appropriately define the concept of the term in order to best explain his invention. It must be interpreted as and concepts.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention; However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various forms, and only one embodiment of the present invention is to complete the disclosure of the present invention, and to those skilled in the art It is provided to fully inform the category.

First, unlike the liquid phase process, the chemical vapor deposition method using an initiator for forming an insulating film to which the insulating film forming method using the iCVD process of the present invention is applied is referred to as an iCVD process. No solvent is used at all. This feature eliminates the need for conventional annealing steps and avoids damage to the device due to solvents.

In addition, unlike the vapor phase process, the iCVD process has a relatively low process temperature (about 10 to 50 degrees of substrate temperature and about 150 to 250 degrees of filament temperature). In addition, the process pressure is about 0.1 to 0.5 Torr, which is higher than that of the conventional CVD process, and does not require the use of a high vacuum pump. In addition, since the temperature for heating the monomer is also lower than 100 ° C., it does not require much energy consumption in the whole process. Since the iCVD process itself can be processed at a very low temperature and is not affected by the substrate at all, there is no precaution in the process.

Furthermore, since iCVD is a process of depositing a polymer using a vinyl polymerization reaction, basically all monomers having vinyl groups can be polymerized. The types of polymers that can be deposited by iCVD are as follows. Here, Table 1 is an organosilicon polymer, Table 2 is a superhydrophobic polymer, Table 3 is a hydrophilic polymer, Table 4 is a hydrophobic polymer.

Table 1

TABLE 2

TABLE 3

Table 4

As can be seen in Figure 2, the insulating film forming method using an iCVD process according to an embodiment of the present invention is a monomer and initiator providing step (S200), heat injection step (S210), free radical forming step (S220), polymer forming step (S230) and the polymer insulating film forming step (S240).

Providing the monomer and the initiator (S200) is a step of providing the monomer and the initiator on the surface of the organic thin film transistors (oTFTs), the 'monomer' is used in the embodiments of the present invention It means a unit that can be used for forming a polymer thin film (insulating film), and as an constituent of the encapsulation film, any organic material having a property of blocking external moisture and oxygen permeation is not limited thereto. Moreover, the 'monomer' is a substance which is volatile in chemical vapor deposition and can be activated by an initiator, and can be vaporized under reduced pressure and elevated temperature, and has one or more vinyl groups, ethyl, ethynyl, propyl, allyl, It is characterized by having a substituent of a butyl group and a phenyl group.

'Initiator' used in the embodiments of the present invention is a substance that induces activation of the first reaction so that the monomers can form a polymer in the process of the present invention. The initiator is preferably a substance capable of pyrolyzing at a temperature lower than the temperature at which the monomer is pyrolyzed to form free radicals. In particular, the "initiator" is not particularly limited as long as it is a substance capable of activating the monomer as a substance that is decomposed by the supply of heat in the reactor to form free radicals. At this time, the initiator that can be used in the embodiments of the present invention may be applied to a thermal initiator (thermal initiator) or UV initiator, and the like, in particular, a thermal initiator of a peroxide radical (peroxide radical) group is used.

Here, the organic thin film transistor used in the present invention is a thin film transistor using an organic semiconductor layer instead of an inorganic (silicon) layer as a channel layer, and the overall structure is not significantly different from a transistor based on silicon. When a voltage is applied to the gate, no current flows due to the insulating film, and an electric field is applied to the semiconductor, thereby acting as a field effect transistor. The operation principle of the device is that the insulating film portion becomes a depletion layer without charge or an accumulation layer with charge depending on the voltage applied to the gate, thereby controlling the amount of current flowing between the source and drain electrodes. This ratio of currents is called the flashing ratio and plays an important role in displays such as computer monitors.

The heat injection step S210 is a step of providing heat to pyrolyze the initiator to form free radicals. Here, the heat provided in the heat injection step (S210) is not limited if the heat provided by a conventional method that can be provided by those of ordinary skill in the art to which the present invention belongs (hereinafter referred to as "an expert") in weather conditions. Do not. Preferably the heat providing of the present invention may be made through a filament, the range of heat provided may be 200 ℃ to 300 ℃. In an embodiment of the present invention, heat is provided by a tungsten filament heated to a set temperature in a vacuum chamber environment in which a vaporized or sublimated monomer and an initiator are present to form an organic polymer insulating film on an organic thin film transistor.

The free radical forming step (S220) is a step of pyrolyzing the initiator through the heat injection step (S210) to form free radicals.

In the polymer forming step (S230), when free radicals are formed by pyrolysis of an initiator after performing the free radical forming step (S220), forming a polymer polymer by chain polymerization of the monomers by activating the monomers using the free radicals. to be.

The polymer insulating film forming step (S240) is a step of forming a polymer insulating film by depositing a polymer polymer by providing heat to the organic thin film transistor by tungsten filament. That is, in the polymer insulating film forming step (S240), when free radicals are formed by thermal decomposition of an initiator, the free radicals activate monomers to induce polymerization of surrounding monomers, and the reaction is continued to form an organic polymer insulating film. .

All kinds of polymers that can be deposited by iCVD can be applied to the kinds described in Tables 1 to 4 above. Meanwhile, the polymer material in this embodiment is exemplified as poly (cyclosiloxane: cyclosiloxane) or poly (perfluorodecylacrylate (perfluorooctyl methacrylate)), and the like. In addition, poly (FMA), poly (IBA), poly (EGDMA), poly (V3D3), poly (PFDA) and poly (V3D3-PFDA copolymer) may be applied.

In this case, the insulating film is preferably coated with a thickness of 10nm or less, and is not limited to this, the thickness may be thicker than 1um or thinner than 10nm.

On the other hand, the insulator properties of the insulating film are determined by the thickness of the polymer, the dielectric constant of the insulator, etc. (C = kA / d, C (Capacitance) is the capacitance, A is the area of the insulator, d is the thickness of the insulator, k is the insulator). In this case, the larger the capacitance, the more efficient the capacitor C is, and when it is difficult to limit the characteristics of the insulator, it is difficult to manufacture a thin polymer in a general manner. It is to make electric capacity superior.

That is, even if the value of k is large in capacitance, if the value of d is large, the value of C becomes small. Therefore, it is difficult to be an excellent insulator. However, if the value of d is small, the value of C is maintained. have. In view of these results, if an insulating film with a thin thickness is formed by iCVD, the capacitance value C is greatly increased when the k value of the polymer is usually between 2.5 and 3.5.

On the other hand, the structure and the main characteristics of the insulating film are shown in Table 5.

Table 5

Process conditions of the insulating film formed by the insulating film forming method using the iCVD process according to the present invention is carried out differently when the polymer material is poly (cyclosiloxane) or poly (perfluorodecylacrylate).

First, when the polymer material is poly (cyclosiloxane), the insulating film process conditions include a vapor flow rate (monomer: initiator) of 2.0 to 3.0: 0.5 to 1.5, a process pressure of 250 to 350 mTorr, and a filament heating temperature of 200 to 300 degreeC, glass substrate cooling temperature is 100 degrees C or less, process time is 1-3 nm / min, Preferably the flow rate of a vapor (monomer: initiator) is 2.5: 1, the process pressure is 300 mTorr, filament Heating temperature is 250 degreeC, glass substrate cooling temperature is 50 degreeC, process time is 2 nm / min.

In addition, when the polymer material is poly (perfluorodecylacrylate), the insulating film process conditions are the flow rate of the vapor (monomer: initiator) is 0.5 ~ 1.5: 0.5 ~ 1.5, the process pressure is 50 ~ 150mTorr, filament heating temperature is 150 ~ 250 ° C., glass substrate cooling temperature is 100 ° C. or less, process time is 50-150 nm / min, preferably steam flow rate (monomer: initiator) is 1: 1, process pressure is 100 mTorr, filament Heating temperature is 200 degreeC, glass substrate cooling temperature is 40 degreeC, and process time is 100 nm / min.

Furthermore, in the graph shown in FIG. 3, when the polymer materials of the insulating film are poly (perfluorodecylacrylate) and poly (cyclotrisiloxane), even at various thicknesses, a very low leakage current of 10 ⁻⁸ A / cm ² or less is observed at 1 MV / cm. . In particular, poly (perfluorodecylacrylate) has the same leakage current value as the leakage current at 100nm even at a thin film thickness of 25nm.

In the graph shown in FIG. 4, when measuring the capacitance of poly (perfluorodecylacrylate) and poly (cyclotrisiloxane) showing low leakage current, both polymer materials showed very stable electrical characteristics even in the high frequency region of 1 MHz. (perfluorodecylacrylate) recorded a capacitance of 35 nF / cm ² at 100 kHz, and poly (cyclotrisiloxane) recorded a capacitance of 45 nF / cm ² at 100 kHz.

Using this to calculate the dielectric constant k, poly (perfluorodecylacrylate) has a dielectric constant of 3.95 and poly (cyclotrisiloxane) has a dielectric constant of 5. Considering that poly (methyl methacrylate) and polystyrene, which are widely used as polymer insulating films, have a dielectric constant of about 3 or less, it can be seen that the polymer insulating films deposited by iCVD are relatively better.

As such, when iCVD is used as in the present invention, the polymer can be deposited without damage to various substrates, thereby being not limited by the substrate material. In addition, it is much easier to fabricate a device having a top gate structure in which a polymer insulating film must be stacked on a semiconductor. Here, when dividing the transistor into a structure, it is divided into a top gate structure and a bottom gate structure according to the position of the gate electrode. In general, a bottom gate structure that is easy to manufacture is commonly used. In other words, when the polymer insulating film is formed by using iCVD, the gate current leakage problem can be solved in the initial bottom emission semiconductor, thereby increasing the utilization of the top gate structure.

Meanwhile, the polymers applicable in the present invention are described as poly (perfluorodecylacrylate) and poly (cyclotrisiloxane), but in addition to poly (FMA), poly (IBA), poly (EGDMA), poly (V3D3), poly (PFDA) and Any one of poly (V3D3-PFDA copolymer) may be substituted.

Table 6 and Table 7 show the electric field strengths for the polymers applicable in the present invention: poly (FMA), poly (IBA), poly (EGDMA), poly (V3D3), poly (PFDA) and poly (V3D3-PFDA copolymer). According to the charge transfer characteristics (JE) and the surface morphology of the iCVD polymer film. At this time, root mean square (RMS) roughness represents a square root square roughness.

Table 6

TABLE 7

5 is a process diagram of manufacturing a fullerene thin film transistor using an insulating film formed by an insulating film forming method using an iCVD process according to an embodiment of the present invention, Figure 6 is an embodiment of the present invention A graph showing the performance of a transistor through a transfer curve and an output curve is shown in a fullerene thin film transistor to which an insulating film manufactured by an insulating film forming method using the iCVD process is applied.

According to these drawings, the film transistor: 100 through the insulating film forming method using the iCVD process of the present invention is a glass substrate 110, Al (aluminum) electrode 120, insulating film 130, fullerene layer 140 and Al A source 150 and a drain electrode 152.

The Al gate electrode 120 is formed on the surface of the glass substrate 110 by thermal vapor deposition.

The insulating film 130 is formed by coating the surface on which the Al gate electrode 120 is thermally deposited using iCVD, and the forming method is a monomer and initiator providing step, a heat injection step, a free radical forming step, and a polymer formation as described above. It includes the step and the polymer insulating film forming step, and the same description as the previous method will be omitted.

The fullerene layer 140 is a layer deposited on the insulating layer 130, and the Al source 150 and the drain electrode 152 are thermally deposited on the fullerene layer 140.

Here, a method of measuring the current-voltage characteristic is to fix the gate voltage constant and change the voltage across the drain, and then measure the current between the source and drain (Output Curve), and to fix the drain voltage and There are two ways to measure the current between source and drain after changing the voltage (Transfer Curve).

For example, a case in which the polymer material in the insulating film 130 is poly (cyclosiloxane) and the thickness of the insulating film is 10 nm or less, that is, 7.1 nm will be described. For example, as shown in FIG. The typical performance of the fuller thin film transistor 100 using the insulating film is the on-off ratio, the electron mobility, and the threshold voltage of the device. The rectification ratio is 106, the charge mobility is 1.22cm2 / Vs, and the threshold voltage is 0.3V.

As shown in FIG. 6 (b), the output curve shows how well the device is driven as the voltage input to the device changes. As the voltage changes by 0.3V, the current flow in the device increases in proportion to the voltage. . That is, it can be confirmed that the insulating film 130 made by using iCVD plays a role well in the device, and thus the device manufacturing yield is high while the electrical characteristics of the device are excellent.

Furthermore, in the method of manufacturing the fuller thin film transistor, when the polymer material of the insulating film 130 is poly (cyclosiloxane) and the thickness of the insulating film is 10 nm or less, 10 nm using iCVD is performed as the polymer poly (cyclotrisiloxane) on the glass substrate 110. The insulating film 130 is coated below. A fullerene, a semiconductor, is deposited thereon, and the Al source 150 and the drain electrode 152 are placed thereon to complete the thin film transistor.

As described above, the present invention has been described by way of limited embodiments and drawings, but the present invention is not limited to the above embodiments, and those skilled in the art to which the present invention pertains various modifications and variations from such descriptions. This is possible.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the claims below but also by the equivalents of the claims.

The present invention relates to a method for forming an insulating film using an iCVD process, the method for forming an insulating film using an iCVD process according to the present invention, in the method for producing an insulating film on an organic thin film transistor, by the heat injected on the organic thin film transistor Pyrolyzing the initiator to form free radicals; Chain polymerizing the monomer by activating the monomer using the free radicals to form a polymer polymer; And depositing the polymer polymer on the organic thin film transistor to form a polymer insulating film.

According to the present invention, the narrow manufacturing width of the insulating film manufactured in the PECVD process or the CVD process can be eliminated through the iCVD process, and the deposition is more uniform than that of the existing process, and the insulation current is very high due to the very low leakage current even at various thicknesses. The rate is excellent in the electrical characteristics of the device, and the production yield of the device is effective. In addition, it is possible to deposit the desired polymer insulating film with the monomer and the initiator in a gaseous condition without using a solvent, especially an organic solvent, there is an effect that can prevent damage to the deposition medium due to the solvent.

Claims

In the method for producing an insulating film on an organic thin film transistor,

Pyrolyzing the initiator by heat injected onto the organic thin film transistor to form free radicals;

Chain polymerizing the monomer by activating the monomer using the free radicals to form a polymer polymer; And

And depositing the polymer polymer on the organic thin film transistor to form a polymer insulating film.
The method of claim 1,

The polymer is iCVD which is one of poly (cyclosiloxane), poly (perfluorodecylacrylate), poly (FMA), poly (IBA), poly (EGDMA), poly (V3D3), poly (PFDA) and poly (V3D3-PFDA copolymer) An insulating film formation method using the process.
The method of claim 2,

When the polymer is poly (cyclosiloxane), the insulating film process conditions are the flow rate of the vapor (monomer: initiator) is 2.0 to 3.0: 0.5 to 1.5, the process pressure is 250 to 350mTorr, filament heating temperature is 200 ~ 300 ℃ The glass substrate cooling temperature is 100 degrees C or less, and the process time is the insulating film formation method using the iCVD process of 1-3 nm / min.
The method of claim 2,

When the polymer is poly (perfluorodecylacrylate), the insulating film process conditions include a vapor flow rate (monomer: initiator) of 0.5 to 1.5: 0.5 to 1.5, a process pressure of 50 to 150 mTorr, and a filament heating temperature of 150 to 250 ° C. The glass substrate cooling temperature is 100 degrees C or less, and the process time is 50-150 nm / min, The insulating film formation method using the iCVD process.