JP5430014B2 - Method for forming SiNxCyOz film - Google Patents

Description

  The present invention relates to a SiNxOyCz film and a thin film forming method, and more particularly to a SiNxOyCz film with improved transparency and a thin film forming method with improved film forming speed.

  BACKGROUND OF THE INVENTION Organic EL (electroluminescence) elements are expected from superior points such as low power consumption, self-emission, and a wide viewing angle as compared with liquid crystals that have been used in the past as information is developed more and more in the future. As a protective film of the organic EL element, for example, a polymer polymer is formed by a vacuum vapor deposition method, and a silicon oxynitride (SiON) film is formed on the polymer polymer by a plasma CVD (chemical vapor deposition) method. The laminated structure is used (see, for example, Patent Document 1).

JP 2003-282250 A (second paragraph, fourth paragraph)

However, the conventional silicon oxynitride film described above has a problem that sufficient transparency as a protective film for the organic EL element cannot be ensured.
In addition, a normal plasma CVD method in which plasma is generated by applying an RF output has a problem that a sufficient film formation rate cannot be ensured. Furthermore, in the plasma CVD method in which plasma is generated by applying RF output to a film formation substrate, the temperature of the film formation substrate rises. There is a problem that the substrate cannot be used.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a SiNxOyCz film with improved transparency.
Another object of the present invention is to provide a thin film forming method capable of improving the film forming speed while suppressing the temperature rise of the film forming substrate.

In order to solve the above problems, the SiNxOyCz film according to the present invention is characterized in that each of x, y and z is in the range of the following formulas (1) to (3).
0.2 <x <1.5 (1)
0.3 <y <0.8 (2)
0.03 <z <0.4 (3)

  According to the SiNxOyCz film according to the present invention, the transparency can be improved by setting the composition range.

In the SiNxOyCz film according to the present invention, the SiNxOyCz film is preferably a protective film for the organic EL element.
In the SiNxOyCz film according to the present invention, the SiNxOyCz film can have a transmittance of 95% or more with light having a wavelength of 400 nm to 800 nm.

  In the SiNxOyCz film according to the present invention, the SiNxOyCz film is formed by a CVD method that decomposes a source gas by inductively coupled plasma generated by applying an ICP output to a one-turn coil. It is preferable.

  The thin film deposition method according to the present invention uses an CVD method in which an ICP output is applied to a one-turn coil to generate inductively coupled plasma, and a source gas containing an organic metal is decomposed by the inductively coupled plasma. A thin film is formed on a substrate to be deposited.

  According to the method for forming a thin film according to the present invention, since the source gas containing the organic metal is decomposed by inductively coupled plasma, the decomposition action can be increased. For this reason, the film-forming speed | rate of a thin film can be improved.

In the thin film deposition method according to the present invention, when a thin film is deposited on the deposition target substrate, an RF output is applied to the deposition target substrate to apply an RF bias to the deposition target substrate. Is preferably generated. Thereby, a dense thin film with better film quality can be formed.
In the thin film forming method according to the present invention, the thin film may be composed of a compound synthesized by carbonization, nitridation, and oxidation.

In the thin film forming method according to the present invention, the thin film is a SiNxOyCz film, and each of x, y, and z in the SiNxCyOz film is preferably in the range of the following formulas (1) to (3). Thereby, the transparency of the SiNxOyCz film can be sufficiently ensured.
0.2 <x <1.5 (1)
0.3 <y <0.8 (2)
0.03 <z <0.4 (3)

  In the thin film deposition method according to the present invention, the source gas may be HMDS, nitrogen gas, and oxygen gas.

  In the thin film deposition method according to the present invention, before the SiNxOyCz film is deposited on the deposition target substrate, an ICP output is applied to a one-turn coil to generate inductively coupled plasma, and the induction It is also possible to clean the surface of the substrate to be deposited by generating plasma of argon gas by coupled plasma. As a result, the adhesion strength between the SiNxOyCz film and the deposition target substrate can be improved.

  As described above, according to the present invention, a SiNxOyCz film with improved transparency can be provided. In addition, according to another aspect of the present invention, it is possible to provide a thin film forming method with an improved film forming speed.

It is a block diagram which shows roughly the film-forming apparatus used when forming the SiNxOyCz film | membrane by embodiment of this invention. It is a figure which shows the relationship between the oxygen gas flow rate and the transmittance | permeability with respect to the wavelength light of 300 nm-800 nm of a SiNxOyCz film | membrane. It is a figure which shows the relationship between an oxygen gas flow rate and the composition ratio in a SiNxOyCz film | membrane. This is the relationship between the oxygen gas flow rate and the element distribution in the SiNxOyCz film, where (a) is oxygen-free, (b) is an oxygen gas flow rate of 5 ccm, and (c) is an oxygen gas flow rate of 10 ccm. It is a figure which shows the relationship between the oxygen gas flow rate by the presence or absence of ICP output, and the film thickness of a SiNxOyCz film | membrane. (A) is a figure which shows element distribution from the surface in the SiNxOyCz film | membrane formed without ICP output (ICP output: 0W), (b) is SiNxOyCz formed with ICP output (ICP output: 300W). It is a figure which shows element distribution from the surface in a film | membrane.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a configuration diagram schematically showing a film forming apparatus used when forming a SiNxOyCz film according to an embodiment of the present invention.

  This film forming apparatus has a film forming chamber 1, and a base material holder 3 for holding a base material 2 is disposed in the film forming chamber 1. A high frequency power source (RF power source) 4 of 13.56 MHz is connected to the substrate holder 3, and the substrate holder 3 also functions as an RF electrode. This high frequency power source 4 applies a high frequency of 13.56 MHz to the base material 2 through the base material holder 3. A heater 5 is disposed around the substrate holder 3, and the substrate 2 is heated by the heater 5. The substrate 2 can be made of various materials and various shapes as long as the SiNxOyCz film is formed. In addition, the base material 2 may be a substrate in which one or more thin films are formed on a substrate.

  The film forming chamber 1 is provided with a gas inlet 10 for introducing a reaction gas. A gas pipe (not shown) for supplying a reaction gas is connected to the gas inlet 10. The gas pipe is provided with a flow meter (not shown) for measuring the gas flow rate and a gas flow controller (not shown) for controlling the gas flow rate. An appropriate amount of raw material gas containing nitrogen gas, oxygen gas and silicon-containing compound is supplied from a gas inlet by a flow meter. In addition, a vacuum pump 13 for evacuating the inside of the film forming chamber 1 is connected.

  Above the base material holder 3, an ICP (inductively-coupled plasma) electrode 6 comprising a high-frequency coil that generates an inductively coupled plasma and promotes a reaction is installed. The ICP electrode 6 is composed of a one-turn coil formed of a flexible member such as a metal flexible tube or a braided wire. In order to prevent the ICP electrode 6 from being excessively heated during use, the inside of the ICP electrode 6 is hollow. The ICP electrode 6 is formed by winding a coil of one turn substantially concentrically with respect to a line extending vertically from the surface of the base material 2 held by the substrate holder 3 vertically to the surface. . In addition, by forming the ICP electrode 6 with a coil of one turn, the size of the film forming chamber 1 can be reduced as compared with the case where a coil wound a plurality of times is used. It can be downsized.

  The ICP electrode 6 is connected to a high frequency power source 8 for ICP through a matching unit 7. The ICP high-frequency power supply 8 supplies a high-frequency current of 13.56 MHz, for example, to the ICP electrode 6 through the matching unit 7 to generate inductively coupled plasma of the processing gas above the substrate 2. ing. Further, an emission spectrometer 12 is attached to the film forming chamber 1, and this emission spectrometer 12 measures the plasma state between the substrate 2 on the substrate holder 3 and the ICP electrode 6. is there.

Next, a method for forming a SiNxOyCz film on a substrate using the film forming apparatus of FIG. 1 will be described. First, the base material 2 as a material to be coated is mounted on the base material holder 3. Next, in order to remove water from the substrate 2, the substrate 2 is heated to a temperature of 120 ° C. by the heater 5, and the film formation chamber 1 is evacuated to 1 × 10 ⁻⁴ Pa or less by the vacuum pump 13. Thereafter, argon gas is introduced into the film forming chamber 1 from the gas inlet 10 and argon plasma is formed on the substrate using the RF power source 4 and the ICP high frequency power source 8 to clean the surface of the substrate 2. To do. By this treatment, the adhesion strength between the SiNxOyCz film and the base material can be improved.

  Thereafter, hexamethyldisilazane (HMDS), nitrogen gas and oxygen gas are introduced into the film forming chamber 1 as silicon compound gases. Next, the RF output of the RF power source 4 is set to 50 W, for example, and the ICP output of the 13.56 MHz ICP high frequency power source 8 is set to 300 W, for example, to generate inductively coupled plasma on the substrate 2. Thereby, a SiNxOyCz film is formed on the substrate 2 by plasma CVD.

  In this case, with only the RF electrode (substrate holder 3), the HMDS decomposition reaction is slow, resulting in a slow deposition rate, resulting in poor productivity and a high carbon content in the deposited SiNxOyCz film. Therefore, the film quality deteriorates. However, the combination of the RF electrode and the ICP electrode can stably generate high-density plasma, facilitates the decomposition of HMDS, increases the deposition rate, and the carbon in the SiNxOyCz film to be deposited. The content of can be kept low. By keeping the carbon content low, the transparency of the SiNxOyCz film can be increased. In this way, a SiNxOyCz film can be formed on the substrate 2.

  In this embodiment, it is possible to form a SiNxOyCz film having better film quality by increasing the ICP output and decreasing the RF output. The reason why the ICP output is increased is that the main action of the ICP electrode is to activate the plasma. By increasing the ICP output, inductively coupled plasma that is high-density plasma can be generated, and the source gas is decomposed. This is because the action is increased, the reactivity is increased, and a dense film with good film quality can be formed. The reason why the RF output is reduced is that the RF electrode mainly applies an RF bias to the substrate, and the temperature increase of the substrate can be suppressed by reducing the RF output. For example, when forming a protective film for an organic EL element, it is particularly preferable to reduce the RF output because the organic EL element is vulnerable to high temperatures. A dense film with good film quality can be formed by generating an RF bias on the substrate.

  According to the above-described embodiment, the source gas is supplied into the film forming chamber 1 having a reduced pressure, an ICP output is applied to the ICP electrode 6 and a high-frequency current is applied to induce induction of high-density plasma above the substrate 2. While generating a coupled plasma stably, a high frequency current is passed through the substrate 2 through the substrate holder 3 to apply an RF bias to the substrate 2, thereby forming a film by CVD using the inductively coupled plasma. . This makes it possible to form a SiNxOyCz film with improved transparency and barrier properties against moisture and the like.

  Further, by increasing the ICP output, it is possible to increase the action of generating inductively coupled plasma, which is high-density plasma, and decomposing the source gas such as HMDS. For this reason, the film formation rate can be dramatically improved as compared with the case where the SiNxOyCz film is formed only by the RF output.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, HMDS is used as the source gas. However, the present invention is not limited to this, and source gas containing other organic metals (MO) such as TEOS (tetraethylorthosilicate) is used. It is also possible.

  Hereinafter, the present invention will be described in more detail with specific examples, but the present invention is not limited to these examples.

Example 1
In this embodiment, in order to confirm that the transparency of the SiNxOyCz film is improved, the film forming apparatus shown in FIG. 1 is used, and a certain amount of HMDS and nitrogen gas are used as reaction gases in the film forming chamber 1 during film forming. A plurality of samples in which a SiNxOyCz film is formed on a substrate are produced by supplying and changing the flow rate of oxygen gas. Specific film forming conditions are as follows.

<Film formation conditions>
Base material: Stainless steel Substrate temperature: 120 ° C
RF output; 50W
ICP output: 300W
HMDS flow rate: 2 ccm (cubic centimeter per minute)
Nitrogen gas flow rate: 50 ccm
Oxygen gas flow rate: 5 ccm, 6 ccm, 7 ccm, 7.5 ccm, 10 ccm
Deposition time: 50 minutes SiNxOyCz film thickness: about 1.9 μm

  Five samples of the SiNxOyCz film formed under the above film forming conditions are prepared for each oxygen gas flow rate, and the transmittance of the five samples of the SiNxOyCz film with respect to light having a wavelength of 300 nm to 800 nm is measured. It shows. In FIG. 2, reference numeral 14 is a measurement result regarding the SiNxOyCz film formed under the film forming condition with an oxygen gas flow rate of 5 ccm, and reference numeral 15 is a measurement regarding the SiNxOyCz film formed under the film forming condition with an oxygen gas flow rate of 6 ccm. The reference numeral 16 is a measurement result regarding the SiNxOyCz film formed under the film forming condition with the oxygen gas flow rate of 7 ccm, and the reference numeral 17 is the SiNxOyCz film formed under the film forming condition with the oxygen gas flow rate of 7.5 ccm. Reference numeral 18 is a measurement result relating to a SiNxOyCz film formed under a film forming condition with an oxygen gas flow rate of 10 ccm.

As shown in FIG. 2, when the flow rate of oxygen gas was 5 ccm, the transmittance was reduced on the shorter wavelength side than 500 nm, and it was confirmed that the transmittance increased on the shorter wavelength side as the oxygen gas flow rate was increased. Therefore, it can be said that the transparency of the SiNxOyCz film can be improved by increasing the oxygen gas flow rate. In other words, when the oxygen gas flow rate is increased, carbon and oxygen react to become CO ₂ , whereby the concentration of C in the SiNxOyCz film can be lowered, and as a result, the transparency of the SiNxOyCz film can be improved. It is considered possible.

  For example, when a SiNxOyCz film is used as a protective film for an organic EL element, it is considered that a transmittance of 95% or more is required for light having a wavelength of 400 nm to 800 nm. According to FIG. 2, by forming a SiNxOyCz film with an oxygen gas flow rate of 5 ccm or more, a transmittance of 95% or more can be obtained for light having a wavelength of 400 nm to 800 nm.

(Example 2)
In this embodiment, in order to confirm the contents of Si, N, O, C, and H in the SiNxOyCz film, the film forming apparatus shown in FIG. A plurality of samples in which a SiNxOyCz film is formed on a substrate are produced by supplying a certain amount of HMDS and nitrogen gas and changing the flow rate of oxygen gas. Specific film forming conditions are as follows.

<Film formation conditions>
Base material: Stainless steel Substrate temperature: 120 ° C
RF output; 50W
ICP output: 300W
HMDS flow rate; 2ccm
Nitrogen gas flow rate: 50 ccm
Oxygen gas flow rate: 0 ccm, 2.5 ccm, 5 ccm, 6 ccm, 7 ccm, 7.5 ccm, 10 ccm
Deposition time: 50 minutes SiNxOyCz film thickness: about 1.9 μm

  Seven samples of the SiNxOyCz film formed under the above film formation conditions were prepared for each oxygen gas flow rate, and the contents of N, O, and C in the SiNxOyCz film of these seven samples were measured. This measurement was performed with a glow discharge emission spectrometer (GDS). The measurement results are shown in FIG. FIG. 3 is a graph showing the relationship between the oxygen gas flow rate and the composition ratio in the SiNxOyCz film.

  As shown in FIG. 3, as the flow rate of oxygen gas increases, Si and O in the SiNxOyCz film increase while N and C decrease. C becomes approximately 0 at% when the oxygen gas flow rate is 7 ccm.

For example, when a SiNxOyCz film is used as a protective film for an organic EL element, the composition ratio shown by the arrow 19 in FIG. Is preferred. Specifically, the range of the composition ratio of the SiNxOyCz film is preferably the following formulas (1) to (3).
0.2 <x <1.5 (1)
0.3 <y <0.8 (2)
0.03 <z <0.4 (3)

  The reason why the composition ratio of N is represented by the above formula (1) is that if the SiNxOyCz film does not contain N to some extent, it cannot function as a protective film for the organic EL element. The reason why the composition ratio of C is expressed by the above formula (2) is that if the amount of C in the SiNxOyCz film is too large, the transparency is lowered.

  FIG. 4 is a diagram showing the relationship between the oxygen gas flow rate and the contents of Si, N, O, C, and H in the SiNxOyCz film. FIG. 4A shows the oxygen gas flow rate of 0 ccm (oxygen among the film formation conditions). (B) is a case where the oxygen gas flow rate is 5 ccm among the film formation conditions, and (c) is a case where the oxygen gas flow rate is 10 ccm among the film formation conditions.

(Example 3)
FIG. 5 shows a case where the film thickness of the SiNxOyCz film formed under the first film-forming conditions in which the ICP output is increased and the RF output is decreased and the ICP output is 0 using the film forming apparatus shown in FIG. It is the figure which compared with the film thickness of the SiNxOyCz film | membrane formed into a film with the 2nd film-forming conditions which enlarged the output.
Specific first and second film forming conditions are as follows.

<First film forming condition>
Base material: Stainless steel Substrate temperature: 120 ° C
RF output; 50W
ICP output: 300W
HMDS flow rate; 2ccm
Nitrogen gas flow rate: 50 ccm
Oxygen gas flow rate: 0 ccm, 2.5 ccm, 5 ccm, 6 ccm, 7 ccm, 7.5 ccm, 10 ccm
Deposition time: 50 minutes

<Second film forming condition>
Base material: Stainless steel Substrate temperature: 120 ° C
RF output; 300W
ICP output: 0W
HMDS flow rate; 2ccm
Nitrogen gas flow rate: 50 ccm
Oxygen gas flow rate: 7 ccm
Deposition time: 50 minutes

FIG. 6A is a diagram showing the relationship between the distance from the surface and the concentration of contained elements in the SiNxOyCz film formed under the second film formation condition using the film formation apparatus shown in FIG.
FIG. 6B shows the distance from the surface and the concentration of contained elements in the SiNxOyCz film formed under the first film formation conditions when the oxygen gas flow rate is 7 ccm using the film formation apparatus shown in FIG. It is a figure which shows the relationship.

  As shown in FIG. 5 and FIG. 6, the film thickness of the SiNxOyCz film formed under the first film-forming conditions in which the ICP output is increased and the RF output is decreased is set to 0 when the ICP output is 0 and the RF output is increased. It was confirmed that the thickness was larger than the thickness of the SiNxOyCz film formed under the film forming conditions of 2. In other words, by increasing the ICP output, it is possible to increase the effect of decomposing the source gas such as HMDS by generating inductively coupled plasma. Therefore, compared with the case where the SiNxOyCz film is formed only by the RF output. The film speed can be dramatically improved. Therefore, productivity can be improved.

  Also, as shown in FIGS. 6A and 6B, the C concentration in the SiNxOyCz film can be kept lower when the film is formed with the ICP output than when the film is formed without the ICP output. Therefore, transparency can be improved by forming a film with ICP output.

DESCRIPTION OF SYMBOLS 1 ... Deposition chamber 2 ... Base material 3 ... Base material holder 4 ... High frequency power supply (RF power supply)
DESCRIPTION OF SYMBOLS 5 ... Heater 6 ... ICP electrode 7 ... Matching device 8 ... High frequency power supply 10 for ICP ... Gas introduction port 12 ... Emission spectrometer 13 ... Vacuum pump 14 ... Measurement regarding SiNxOyCz film formed on the film-forming conditions that the oxygen gas flow rate is 5 ccm Result 15: Measurement result about SiNxOyCz film formed under film formation condition with oxygen gas flow rate of 6 ccm 16: Measurement result about SiNxOyCz film formed under film formation condition with oxygen gas flow rate of 7 ccm 17 ... Oxygen gas flow rate of 7.5 ccm Measurement result 18 relating to SiNxOyCz film formed under the film forming conditions of the above .... Measurement result 19 relating to SiNxOyCz film formed under the film forming condition where the oxygen gas flow rate is 10 ccm ... Range of composition ratio that can ensure transparency and the like

Claims (6)

By applying an ICP output to a one-turn coil to generate inductively coupled plasma, and using a CVD method that decomposes a source gas containing an organic metal by the inductively coupled plasma, carbonization, nitridation, and A method of forming a SiNxOyCz film made of a compound synthesized by oxidation ,
Method of forming SiNxCyOz film, wherein x in the SiNxCyOz film, each y and z is in the range of formula (1) to (3).
0.2 <x <1.5 (1)
0.3 <y <0.8 (2)
0.03 <z <0.4 (3) 2. The method of forming a SiNxCyOz film according to claim 1 , wherein the SiNxOyCz film has a transmittance of 95% or more with light having a wavelength of 400 nm to 800 nm. According to claim 1 or 2, the film forming method of SiNxCyOz film, wherein the SiNxOyCz film is a protective film of an organic EL device. In any one of claims 1 to 3, RF bias said time of forming the SiNxCyOz film on the deposition target substrate, the said deposition target substrate by applying an RF output to the deposition target substrate A method of forming a SiNxCyOz film , wherein In any one of claims 1 to 4, the film formation method of SiNxCyOz film wherein the raw material gas is HMDS, nitrogen gas and oxygen gas. In any one of claims 1 to 5, wherein before forming the SiNxCyOz film on the deposition target substrate, to generate inductively coupled plasma by applying the ICP output per turn of the coil, the inductive coupling A method of forming a SiNxCyOz film , wherein the surface of the substrate to be deposited is cleaned by generating plasma of argon gas by plasma.

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