Film forming method and film forming apparatus

There is provided a method of forming a sealing film to seal a device formed on a substrate, including: supplying a mixture gas including a silicon-containing gas and a halogen element-containing gas or a mixture gas including a silicon-containing gas and a gas containing a functional group having an electronegative property stronger than that of nitrogen, as a first mixture gas, into a processing container; generating plasma of the first mixture gas within the processing container; and forming a first sealing film to cover the device using the first mixture gas activated by the plasma.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Japanese Patent Applications Nos. 2014-129522 and 2015-096738, filed on Jun. 24, 2014 and May 11, 2015, respectively, in the Japan Patent Office, the disclosures of which are incorporated herein in their entirety by reference.

TECHNICAL FIELD

Various aspects and embodiments of the present disclosure relate to a film forming method and a film forming apparatus.

BACKGROUND

An organic electroluminescence (EL) device that emits light using an organic compound generally includes a structure in which an organic layer formed on a glass substrate is sandwiched between a positive electrode layer (anode) and a negative electrode layer (cathode). The organic layer is vulnerable to moisture. As such, when the moisture is mixed into the organic layer, characteristics of the organic layer are changed to cause a non-emitting point (dark spot). This shortens a lifespan of the organic EL device. Thus, it is very important to increase a sealing property of a film such that ambient moisture or oxygen does not penetrate through the organic EL device.

As a method of protecting the organic layer from ambient moisture or the like, for example, there is a method in which a sealing can is formed of aluminum or the like. According to this method, the sealing can is attached to the organic EL device with a sealant. In addition, a drying agent is applied to the interior of the sealing can. By doing this, the organic EL device is sealed and dried. This prevents moisture from being mixed into the organic EL device.

In such a method, however, the organic EL device needs to have a certain degree of thickness as a whole to ensure high resistance against moisture. This fails to obtain the original advantages of the organic EL device, such as thin, light, and bendable characteristics.

SUMMARY

Some embodiments of the present disclosure provide a film forming method and a film forming apparatus, which are capable of providing a sealing film to seal a device such as an organic EL device, the sealing film having a high moisture-proof property and a thin thickness.

According to one embodiment of the present disclosure, there is provided a method of forming a sealing film to seal a device formed on a substrate, including: supplying a mixture gas including a silicon-containing gas and a halogen element-containing gas or a mixture gas including a silicon-containing gas and a gas containing a functional group having an electronegative property stronger than that of nitrogen, as a first mixture gas, into a processing container; generating plasma of the first mixture gas within the processing container; and forming a first sealing film to cover the device using the first mixture gas activated by the plasma.

According to another embodiment of the present disclosure, there is provided a film forming apparatus, including: a processing container; a gas supply unit configured to supply a first mixture gas into the processing container; a plasma generating unit configured to generate plasma of the first mixture gas within the processing container; and a controller configured to execute the aforementioned film forming method.

DETAILED DESCRIPTION

A film forming method according to one embodiment is a method of forming a sealing film to seal a device formed on a substrate. The film forming method includes: a first supply step of supplying a mixture gas including a silicon-containing gas and a halogen element-containing gas or a mixture gas including a silicon-containing gas and a gas containing a functional group having an electronegative property stronger than that of nitrogen, as a first mixture gas, into a processing container; a first generation step of generating plasma of the first mixture gas within the processing container; and a first film-forming step of forming a first sealing film to cover the device using the first mixture gas activated by the plasma.

An example of the silicon-containing gas may include a silane-based gas. The silane-based gas refers to a gas represented by SinH2n+1(where n is a natural number) such as monosilane (in step SiH4), disilane (in step Si2H6), or trisilane (in step Si3H8).

Further, in the film forming method according to one embodiment, the first mixture gas may include a nitrogen-containing gas, a silicon-containing gas, and a fluorine-containing gas.

Further, in the film forming method according to one embodiment, in the first mixture gas, a ratio of a flow rate of the nitrogen-containing gas to the silicon-containing gas may fall within a range from 0.8 to 1.1, and a ratio of a flow rate of the fluorine-containing gas to the silicon-containing gas may fall within a range from 0.1 to 0.4.

Further, in the film forming method according to one embodiment, the nitrogen-containing gas may be an N2gas or an NH3gas, the silicon-containing gas may be an SiH4gas, and the fluorine-containing gas may be a fluorine-containing silicon compound, for example, any one of an SiF4gas, an SiH3F gas, an SiH2F2gas, and an SiHxF4-xgas.

Further, in the film forming method according to one embodiment, the halogen element-containing gas may be any one of an SiCl4gas, an SiHxCl4-xgas, an SiH3F gas, and an SiHxFyClzgas.

Further, in the film forming method according to one embodiment, when the fluorine-containing gas is included as the halogen element-containing gas in the first mixture gas, a concentration of fluorine in the first sealing film may be 10 atom % or less.

Further, in the film forming method according to one embodiment, when the chlorine-containing gas is included as the halogen element-containing gas in the first mixture gas, a concentration of chlorine in the first sealing film may be 10 atom % or less.

Furthermore, the film forming method according to one embodiment may further include: a second supply step of supplying a second mixture gas including the silicon-containing gas, which does not include both the halogen element-containing gas and the gas containing a functional group having an electronegative property stronger than that of nitrogen, into the processing container; a second generation step of generating plasma of the second mixture gas within the processing container; and a second film-forming step of forming a second sealing film to cover the first sealing film formed in the first film-forming step using the second mixture gas activated by the plasma.

Further, in the film forming method according to one embodiment, a thickness of the second sealing film is 2 to 4 times as large as the first sealing film.

Further, in the film forming method according to one embodiment, the first mixture gas may include a silicon-containing gas, a halogen element-containing gas and a nitrogen-containing gas, or a silicon/halogen element-containing gas and a nitrogen-containing gas, and the second mixture gas may include a silicon-containing gas and a nitrogen-containing gas.

Further, in the film forming method according to one embodiment, the first mixture gas may include an SiH4gas, an SiF4gas and an N2gas, or an SiHxF4-xgas and an NH3gas, and the second mixture gas may include an SiH4gas and an N2gas.

Furthermore, the film forming method according to one embodiment may further include: a third supply step of supplying the second mixture gas into the processing container; a third generation step of generating plasma of the second mixture gas within the processing container; and a third film-forming step of forming a third sealing film to cover the device using the second mixture gas activated by the plasma, before the first film-forming step is performed. In some embodiments, the first film-forming step may form the third sealing film to cover the third sealing film formed in the third film-forming step using the first mixture gas activated by the plasma.

Further, in the film forming method according to one embodiment, a thickness of the third sealing film may be 0.5 to 1.5 times as large as that of the first sealing film.

Further, in the film forming method according to one embodiment, assuming that a set of the first supply step, the first generation step and the first film-forming step refers to a first process, a set of the second supply step, the second generation step and the second film-forming step refers to a second process, and a set of the third supply step, the third generation step and the third film-forming step refers to a third process, the first process and the third process may be alternately repeated a plurality of times before the second process is performed.

Further, in the first supply step of the film forming method according to one embodiment, the halogen element-containing gas or the gas containing a functional group having an electronegative property stronger than that of nitrogen in the first mixture gas may be incremented from zero to a predetermined level, and subsequently, may be decremented from the predetermined level to zero.

Further, in the first supply step of the film forming method according to one embodiment, the fluorine-containing gas may be used as the halogen element-containing gas. The predetermined level may be adjusted such that a maximum concentration value of fluorine in the first sealing film falls within a range from 4 to 6 atom %.

Further, in the film forming method according to one embodiment, the functional group having an electronegative property stronger than that of nitrogen may be a carbonyl group or a carboxylate group.

Further, in the film forming method according to one embodiment, the carbonyl group may be a functional group represented by —C(═O)—; and the carboxylate group may be a functional group represented by (R)—COOH.

Further, in the film forming method according to one embodiment, a temperature of the substrate in the first film-forming step may range from 10 to 70 degrees C.

A film forming apparatus according to another embodiment includes: a processing container; a gas supply unit configured to supply a first mixture gas into the processing container; a plasma generating unit configured to generate plasma of the first mixture gas within the processing container; and a controller configured to execute the aforementioned film forming method.

Hereinafter, some embodiments of the film forming method and the film forming apparatus will be described in detail with reference to the accompanying drawings. Further, the disclosed disclosure is not limited to the embodiments. Also, the embodiments may be appropriately combined unless a conflict arises.

[Configuration of Film Forming Apparatus10]

FIG. 1is a longitudinal sectional view showing an example of a film forming apparatus10. The film forming apparatus10is configured as a plasma processing apparatus using an inductively-coupled plasma (ICP). The film forming apparatus10includes an airtight processing container1having a square tube shape, which is formed of, e.g., aluminum whose inner wall surface is anodized. The processing container1has a configuration which can be assembled and is grounded by a ground line1a. The processing container1is vertically divided into an antenna chamber3and a processing chamber4by a dielectric wall2. The dielectric wall2constitutes a ceiling wall of the processing chamber4. The dielectric wall2is formed of a ceramic such as Al2O3, quartz, or the like.

A shower housing11through which a process gas is supplied is fixed into a lower portion of the dielectric wall2. The shower housing11is formed in, e.g., a cross shape, and supports the dielectric wall2from below. Further, the shower housing11that supports the dielectric wall2is suspended from the ceiling of the processing container1by a plurality of suspenders (not shown).

The shower housing11is formed of a conductive material, in some embodiments, a metal such as aluminum whose inner surface is anodized to prevent the generation of contamination. A gas flow channel12, which horizontally extends, is formed in the shower housing11. A plurality of gas discharge holes12ais formed to extend downwardly while communicating with the gas flow channel12. Meanwhile, a gas supply pipe20ais installed in the center of an upper surface of the dielectric wall2to communicate with the gas flow channel12. The gas supply pipe20ais installed to penetrate through the ceiling of the processing container1outwardly, and is coupled to a gas supply system20.

The gas supply system20includes gas supply sources200,203and206, flow rate controllers201,204and207, valves202,205and208.

The gas supply source200which supplies a first gas containing, e.g., nitrogen or the like, is coupled to the gas supply pipe20athrough the flow rate controller201such as a mass flow controller, and the valve202. The gas supply source203which supplies a second gas containing, e.g., silicon or the like, is coupled to the gas supply pipe20athrough the flow rate controller204such as a mass flow controller, and the valve205. The gas supply source206which supplies a third gas containing, e.g., fluorine or the like, is coupled to the gas supply pipe20athrough the flow rate controller207such as a mass flow controller, and the valve208.

A process gas supplied from the gas supply system20is introduced into the shower housing11through the gas supply pipe20a, and subsequently, is discharged inward of the processing chamber4through the gas discharge holes12aformed in the lower surface of the shower housing11.

A support shelf5is installed between a sidewall3aof the antenna chamber3and a sidewall4aof the processing chamber4in the processing container1to protrude inward of the processing container1. The dielectric wall2is mounted on the support shelf5.

A radio frequency (RF) antenna13is disposed above the dielectric wall2within the antenna chamber3such that the RF antenna13faces the dielectric wall2. The RF antenna13is spaced apart from the dielectric wall2by a predetermined distance (e.g., 50 mm or lower) with spacers13aformed of an insulating member interposed therebetween. Four power feed members16, which extend vertically, are installed in the vicinity of a central portion of the antenna chamber3. The power feed members16are coupled to an RF power source15through a matcher14. The power feed members16are installed around the gas supply pipe20a.

The RF power source15supplies an RF power of a predetermined frequency (e.g., 13.56 MHz) to the RF antenna13. The supply of RF power to the RF antenna13forms an induced electric field within the processing chamber4. The induced electric field generates plasma of the process gas discharged from the shower housing11. An output of the RF power source15is properly set to have a sufficient value to generate the plasma. A set of the RF antenna13and the shower housing11is an example of a plasma generating unit.

A susceptor22on which a glass substrate G is loaded, is installed in a lower portion of the processing chamber4such that the susceptor22faces the RF antenna13with the dielectric wall2interposed therebetween. The susceptor22is formed of a conductive material, e.g., aluminum whose surface is anodized. The glass substrate G loaded on the susceptor22is adsorptively held on the susceptor22by an electrostatic chuck (not shown).

The susceptor22is supported by a hollow post25while being received in a conductive frame24. The post25penetrates through the lower portion of the processing container1while keeping the processing container1in an airtight state. Further, the post25is supported by a lifting mechanism (not shown) disposed outside of the processing container1such that the susceptor22is moved upward and downward by the lifting mechanism when loading or unloading the glass substrate G into or from the processing container1.

In addition, a bellows26configured to air-tightly surround the prop25is disposed between the conductive frame24that receives the susceptor22and the lower portion of the processing container1. This allows the susceptor22to be moved up and down while maintaining airtightness in the processing chamber4. In addition, an opening27athrough which the glass substrate G is loaded and unloaded, and a gate valve27for opening and closing the opening27aare installed in the sidewall4aof the processing chamber4.

The susceptor22is coupled to an RF power source29through a power feed bar25ainstalled within the hollow post25and a matcher28. The RF power source29applies a bias RF power of a predetermined frequency (e.g., 6 MHz) to the susceptor22. Then, ions of plasma generated within the processing chamber4are effectively introduced to the glass substrate G.

Further, the susceptor22is provided with a temperature control mechanism (not shown) and a temperature sensor (not shown). The temperature control mechanism includes a heating unit such as a ceramic heater, a coolant flow channel or the like to control a temperature of the glass substrate G. Pipes and lines connected to components such as the temperature control mechanism and the temperature sensor are led out from the processing container1through the hollow post25. The lower portion of the processing chamber4is coupled to an exhaust device30equipped with a vacuum pump or the like through an exhaust pipe31. The exhaust device30exhausts gas within the processing chamber4such that the interior of the processing chamber4is maintained in a predetermined vacuum atmosphere.

The film forming apparatus10is connected to a controller50including a microprocessor (computer). Respective components, e.g., a power supply system including the RF power source15and the RF power source29, a gas supply system, a driving system and the like, of the film forming apparatus10are controlled by the controller50. The controller50is connected to a user interface51, which includes a keyboard that enables an operator to input a command for managing the film forming apparatus10, a display that visually displays the operating state of the film forming apparatus10, and the like.

Further, the controller50is connected to a storage part52which stores a control program for executing various processes in the controller50, process recipes for causing the respective components of the film forming apparatus10to execute processes pursuant to processing conditions. The control programs, the process recipes or the like are stored in a storage medium of the storage part52. The storage medium may include a hard disk or a semiconductor memory, or may include a portable storage medium such as a CDROM, a DVD, or a flash memory. Also, the control programs, the process recipes or the like may be transmitted from other apparatus via a communication line, and may be properly stored in the storage part52.

The controller50may read out and execute a certain control program, a process recipe or the like from the storage part52in response to an instruction inputted by a user through the user interface51, thus realizing a desired process in the film forming apparatus10.

FIG. 2is a plan view showing an example of a configuration of the RF antenna13. As shown inFIG. 2, the RF antenna13is, e.g., an octuple antenna whose outer shape is a substantially square shape. The RF antenna13includes eight antenna lines130to137which extend in a vortex shape swirling from the center of the RF antenna13to the circumference thereof. The eight antenna lines130to137are divided into four sets of paired antenna lines, each set being connected to the respective one of four power feed units41to44. Each of the four power feed units41to44is connected to the respective one of the four power feed members16.

The eight antenna lines130to137are grounded through condensers18, respectively. The eight antenna lines130to137have the substantially same length. Capacitances of the condensers18connected to end portions of the antenna lines130to137are also substantially the same. Thus, currents flowing through each of the eight antenna lines130to137have the substantially same value.

Hereinafter, a schematic operation of forming a predetermined film on a substrate using the film forming apparatus10configured as above will be described.

First, the gaste valve27is opened, and then the substrate is loaded into the processing chamber4by a transfer mechanism (not shown) through the opening27aand mounted on a mounting surface of the susceptor22. The controller50controls the electrostatic chuck (not shown) to adsorptively hold the substrate on the susceptor22.

Thereafter, the controller50controls the gas supply system20to supply the process gas into the processing chamber4through the gas discharge hole12of the shower housing11. Further, the controller50controls the exhaust device30to vacuum-exhaust the interior of the processing chamber4through the exhaust pipe31. By doing so, the interior of the processing chamber4is maintained in a predetermined pressure atmosphere.

Subsequently, the controller50controls the RF power source29to apply the RF power of, e.g., 6 MHz, to the susceptor22. Further, the controller50controls the RF power source16to apply the RF power of, e.g., 13.56 MHz, to the RF antenna13. Thus, a uniform induced electric field is formed within the processing chamber4.

The induced electric field generates an inductively-coupled plasma of a high density. The generated plasma leads to the dissociation of the process gas supplied into the processing chamber4. Also, generated film-forming specifies are deposited on the substrate so that a film of a predetermined material is formed on the substrate.

[Procedure of Manufacturing Light Emitting Module100]

FIG. 3is a flowchart showing an example of a process of manufacturing a light emitting module100according to one embodiment.FIG. 4is a cross-sectional view showing an example of a structure of the light emitting module100.

First, an anti-reflective film101is formed on the glass substrate G using a silicon nitride (in step SiN) or the like (in step S10). Thereafter, a transparent electrode102is formed on the anti-reflective film101using an indium tin oxide (ITO), a zinc oxide (ZnO) or the like (in step S11). Subsequently, an organic light emitting layer103including a light emitting material such as a low molecular fluorescent pigment, a fluorescent polymer, a metal complex or the like is formed on the transparent electrode102(in step S12).

Subsequently, a metal electrode104is formed on the organic light emitting layer103using, e.g., aluminum (in step S13). Through a series of steps S10to S13, an organic EL device106including the anti-reflective film101, the transparent electrode102, the organic light emitting layer103and the metal electrode104is formed on the glass substrate G. Thereafter, a sealing film105is formed to cover the organic EL device106(in step S14). In this way, for example, the light emitting module100having the structure as shown inFIG. 4is obtained.

[Details of Sealing Film Forming Step]

FIG. 5is a flowchart showing an example of step of forming the sealing film105according to the first embodiment. This step is performed using, e.g., the film forming apparatus10shown inFIG. 1.

First, the gate valve27of the film forming apparatus10is opened, and the glass substrate G on which the organic EL device106is formed using other apparatus is loaded into the processing chamber4through the opening27a(in step S100). Thereafter, the controller50controls the electrostatic chuck to adsorb the glass substrate G on the susceptor22.

Subsequently, the controller50controls the flow rate controller201and the valve202of the gas supply system20to discharge the first gas into the processing chamber4through the gas discharge holes12aof the shower housing11, thus supplying the first gas into the processing chamber4(in step S101). In this embodiment, an example of the first gas is an N2gas. The controller50controls the flow rate controller201to adjust a flow rate of the first gas to, e.g., 27 sccm.

Subsequently, the controller50controls the exhaust device30to exhaust the gas introduced into the processing chamber4through the exhaust pipe31, thus adjusting the interior of the processing chamber4to a predetermined pressure atmosphere (in step S102). Specifically, the controller50controls the exhaust device30to vacuum-exhaust the interior of the processing chamber4such that the internal pressure of the processing chamber4is adjusted to, e.g., 0.5 Pa.

Subsequently, the controller50controls the RF power source29to apply the RF power of, e.g., 6 MHz, to the susceptor22. Also, the controller50controls the RF power source15to apply the RF power of, e.g., 13.56 MHz, to the RF antenna13. This forms an induced electric field within the processing chamber4by the RF antenna13. The RF power applied to the RF antenna13is, e.g., 2000 W. The induced electric field formed within the processing chamber4generates plasma of the first gas within the processing chamber4(in step S103).

Thereafter, the controller50controls each of the flow rate controller204, the valve205, the flow rate controller207and the valve208of the gas supply system20such that the second and third gases are introduced into the processing chamber4through the gas discharge holes12aof the shower housing11. Thus, the second and third gases are supplied into the processing chamber4(in step S104). In this embodiment, the second gas is, e.g., a SiH4gas, and the third gas is, e.g., a SiF4gas.

The controller50controls the flow rate controller204such that a ratio of a flow rate of the first gas (in this embodiment, the N2gas) to the second gas (in this embodiment, the SiH4gas) falls within, e.g., a range from 0.8 to 1.1. In this embodiment, since the flow rate of the first gas is, e.g., 27 sccm, the controller50controls the flow rate controller201and the flow rate controller204such that the flow rate of the second gas falls within, e.g., a range from 26 to 31 sccm.

Further, the controller50controls the flow rate controller204and the flow rate controller207such that a ratio of a flow rate of the second gas (in this embodiment, the SiH4gas) to the third gas (in this embodiment, the SiF4gas) falls within, e.g., a range from 0.1 to 0.4. Specifically, the controller50controls the flow rate controller204such that the flow rate of the second gas falls within, e.g., a range from 26 to 31 sccm, and controls the flow rate controller207such that the flow rate of the third gas falls within, e.g., a range from 5 to 10 sccm.

Thus, plasma of a mixture gas of the first gas, the second gas and the third gas is generated within the processing chamber4. The generated plasma leads to the disassociation of the first gas, the second gas and the third gas, and film-forming species generated by the disassociation start to be deposited on the organic EL device106formed on the glass substrate G to cover the organic EL device106.

Thereafter, the controller50waits for a predetermined period of time until the sealing film105has a predetermined thickness by the deposition of the film-forming species (in step S105). After the predetermined period of time elapses, the controller50controls the RF power source15and the RF power source29to stop the application of the RF powers, and controls the valve202, the valve205and the valve208to block the flow of the first gas, the second gas and the third gas (in step S106). Subsequently, the controller50controls the exhaust device30to vacuum-exhaust the interior of the processing chamber4through the exhaust pipe31. Thereafter, the gate valve27is opened and the light emitting module100is unloaded from the processing chamber4through the opening27a.

In the sealing film forming step shown inFIG. 5, process conditions according to this embodiment are summarized as follows:

Internal pressure of processing chamber4: 0.5 Pa

Temperature of glass substrate G: 70 degrees C.

Concentration of fluorine of sealing film105: 10 atom % or less

Wherein, Gap indicates a distance between the dielectric wall2and the glass substrate G. In this embodiment, the Gap is 150 mm, but may range from 80 to 200 mm. Also, in this embodiment, the internal pressure of the processing chamber4is 0.5 Pa, but may range from 0.5 to 2 Pa. Also, in this embodiment, the temperature of the glass substrate G is 70 degrees C., but may range from 10 to 70 degrees C.

In general, although an SiN film is amorphous, the SiN film is not completely uniform and is grown in a particle shape during a film forming process so that the SiN film has a structure in which particles are collected. The interior of the particles are very dense, but fine gaps are formed between respective particles. As such, in some cases, the gaps serve as paths along which H2O (moisture) infiltrates or penetrates. Therefore, by strengthening a connection between the SiN particles, it is possible to more strongly prevent the moisture from infiltrating into or penetrating through the gaps. Here, when the SiN film is formed using a silicon-containing material gas, hydrogen is mixed into the SiN film. This hydrogen forms a hydrogen bond between SiN particles in the SiN film. Thus, the connection of the SiN particles are strengthened, compared with an SiN film including only SiN bonds, forming an SiN film having a density higher than that of the SiN film including only SiN particles.

Further, in the SiN film, a hydrogen atom assumes a strong positive electric charge due to the hydrogen bond. A water molecule is a polar molecule, and an oxygen atom of the water molecule assumes a negative electric charge. Thus, the oxygen atom of the water molecule that enters the SiN film is attracted to the hydrogen bond within the SiN film. Accordingly, the SiN film mixed with hydrogen prevents the water molecule from passing therethrough.

Also, in the hydrogen-mixed SiN film, a hydrogen bond exists between NH . . . NH. In the sealing film forming step, a fluorine-containing SiF4gas is added so that the fluorine is mixed into the SiN film, thus generating a hydrogen bond between NH4+. . . F−in the SiN film.

FIG. 6is a view showing an example of a strong-weak relationship of a hydrogen bond, which is disclosed the following document.

FIG. 6is a view showing an arrangement of various types of hydrogen bonds according to strengths of bonds. In the left side ofFIG. 6, a strong hydrogen bond is manifested. Further, a portion positioned to a more upper side in a horizontal axis ofFIG. 6manifests a stronger hydrogen bond. As shown inFIG. 6, a hydrogen bond between NH4+. . . F−is stronger than a hydrogen bond between NH . . . NH (see an arrow indicated by a dotted line inFIG. 6). Thus, when the fluorine-containing SiF4gas is added to the SiN film, the hydrogen bond between NH4+. . . F−is formed in the SiN film so that a hydrogen bond between the SiN particles is strengthened. Accordingly, a connection between the SiN particles in the SiN film is strengthened, thus further increasing a film density of the SiN film. This reduces a gap through which the water molecule passes. Accordingly, in the SiN film formed by adding the SiF4gas, the water molecule is further prevented from passing through the gap, thus enhancing a moisture-proof property of the sealing film.

In this case, if the concentration of fluorine in the sealing film105is too high, fluorine may react with moisture in the atmosphere, thus undergoing a color change. Because of this, in this embodiment, a ratio of a flow rate of the SiF4to the SiH4gas is controlled to be fallen within, e.g., a range from 0.1 to 0.4, such that the concentration of fluorine in the sealing film105is 10 atom % or less. In some embodiments, for example, when a chlorine-containing gas is used as the third gas, a ratio of a flow rate of the chlorine-containing gas to the SiH4gas may be controlled such that the concentration of chlorine in the sealing film105is 10 atom % or less.

So far, the first embodiment has been described. According to the film forming apparatus10of this embodiment, it is possible to provide the sealing film of a high moisture-proof property. Thus, it is possible to manufacture the light emitting module100having a thin thickness and the high moisture-proof property.

Hereinafter, a second embodiment will be described. A sealing film105A of the second embodiment is different from the sealing film105of the first embodiment in that the sealing film105A of the second embodiment has a multi-layered structure. Further, a configuration of a film forming apparatus used in the second embodiment is the same as that of the film forming apparatus10of the first embodiment described with reference toFIGS. 1 and 2, and thus, a detailed description thereof will be omitted. Also, an outline of a procedure of manufacturing a light emitting module100A according to the second embodiment is also the same as that of the procedure of manufacturing the light emitting module100according to the first embodiment described with reference toFIG. 3, and thus, a detailed description thereof, except for the matters described hereinafter, will be omitted.

[Structure of Light Emitting Module100A]

FIG. 7is a cross-sectional view showing an example of a structure of the light emitting module100A according to the second embodiment. As shown inFIG. 7, for example, the light emitting module100A includes an organic EL device106stacked on the glass substrate G, and a sealing film105A stacked on the organic EL device106to cover the organic EL device106. The sealing film105A of this embodiment includes a first film107, a second film108, and a third film109.

The first film107having a thickness d1is stacked on the organic EL device106to cover the organic EL device106. Subsequently, the second film108having a thickness d2is stacked on the first film107to cover the first film107. Thereafter, the third film109having a thickness d3is stacked on the second film108to cover the second film10. In this embodiment, the thickness dl of the first film107is 0.5 to 1.5 times the thickness d2of the second film108. Further, in this embodiment, the thickness d3of the third film109is two times or greater than (e.g., within a range from 2 to 4 times) the thickness d2of the second film108.

The second film108is an SiN film added with fluorine. In this embodiment, fluorine of a concentration ranging from 4 to 6 atom % (e.g., 5 atom %) is added to the second film108. Further, an element added to the second film108may be a halogen element such as chlorine, in addition to fluorine. In some embodiments, a molecule having a functional group with an electronegative property stronger than that of nitrogen may be added to the second film108. Further, the first film107and the third film109are SiN films in which a halogen element such as fluorine or a molecule having a functional group with an electronegative property stronger than that of nitrogen is not added.

FIG. 8is a view showing an example of a relationship between a concentration of fluorine and a film density of the SiN film. The film density of the SiN film changes depending on the concentration of fluorine included in the SiN film. For example, as seen from the experimental result shown inFIG. 8, when the concentration of fluorine included in the SiN film ranges from 4 to 6 atom %, the film density of the SiN film has a maximum value. As the film density of the second film108as the SiN film increases, a gap through which water molecule passes is reduced. This enhances a moisture-proof property of the sealing film105A that includes the second film108.

Meanwhile, if the second film108containing fluorine is stacked on the organic EL device106without forming the first film107between the organic EL device106and the second film108, the organic EL device106may be damaged by fluorine contained in the second film108. For this reason, the organic EL device106is covered with the fluorine-free first film107, and subsequently, the second film108containing fluorine is stacked on the first film107. This prevents the organic EL device106from being damaged by fluorine contained in the second film108.

Further, if the second film108is exposed to the atmosphere, fluorine contained in the second film108reacts with, e.g., oxygen of a high concentration, in the atmosphere, thus degrading the second film108. This degrades a film density of the second film108, which results in a reduced moisture-proof property. To address this, in this embodiment, the third film109is stacked on the second film108. Thus, the second film108is protected by the third film109from the atmosphere. Therefore, the oxidation of the second film108can be restrained by the third film109, thus suppressing the moisture-proof property of the second film108from being reduced.

[Details of Sealing Film Forming Step]

FIG. 9is a flowchart showing an example of a sealing film forming step according to a second embodiment.FIG. 10is a view showing an example of a change in a flow rate of each process gas included in a mixture gas in the second embodiment. The sealing film forming step according to this embodiment is performed using, e.g., the film forming apparatus10shown inFIG. 1.

First, the gate valve27of the film forming apparatus10is opened, and the glass substrate G on which the organic EL device106is formed by other device is loaded into the processing chamber4through the opening27a(in step S200). Thereafter, the controller50controls the electrostatic chuck to adsorb the glass substrate G through the susceptor22.

Subsequently, for example, at a time t1shown inFIG. 10, the controller50controls the flow rate controller201and the valve202to discharge the first gas into the processing chamber4through the gas discharge holes12aof the shower housing11, thus starting to supply the first gas into the processing chamber4(in step S201). In this embodiment, the first gas is, e.g., an N2gas. The controller50controls the flow rate controller201to adjust a flow rate of the first gas to, e.g., 27 sccm.

Thereafter, the controller50controls the exhaust device30to exhaust the gas introduced into the processing chamber4through the exhaust pipe31, thus adjusting the interior of the processing chamber4to a predetermined pressure atmosphere (in step S202). In some embodiments, the controller50controls the exhaust device30such that an internal pressure of the processing chamber4is, e.g., 0.5 Pa.

Subsequently, the controller50controls the RF power source29to apply an RF power of, e.g., 6 MHz, to the susceptor22. Further, the controller50controls the RF power source15to apply an RF power of, e.g., 13.56 MHz, to the RF antenna13. The application of the RF power to the RF antenna13forms an induced electric field within the processing chamber4. The RF power applied to the RF antenna13is, e.g., 2000 W. The induced electric field formed within the processing chamber4generates plasma of a mixture gas containing the first gas within the processing chamber4(in step S203).

Thereafter, for example, at a time t2shown inFIG. 10, the controller50controls the flow rate controller204and the valve205to discharge the second gas into the processing chamber4through the gas discharge holes12aof the shower housing11, thus starting to supply the second gas into the processing chamber4(in step S204). In this embodiment, the second gas is, e.g., an SiH4gas. The controller50controls each of flow rates of the first and second gases such that the sum of the flow rates of the first and second gases is substantially equal to the sum of the flow rates of the first to third gases in the first embodiment, for example. In this embodiment, since in step S201, the flow rate of the first gas has been adjusted to, e.g., 27 sccm, the controller50controls the flow rate controller204such that the flow rate of the second gas is, e.g., 36 sccm. Thus, the plasma generated within the processing chamber4leads to the disassociation of the first gas and the second gas, and film-forming species generated by the disassociation starts to be deposited on the organic EL device106formed on the glass substrate G to cover the organic EL device106. The controller50waits for a first predetermined period of time until the first film107having a thickness d1is stacked on the organic EL device106by the deposition of the film-forming species (in step S205).

Subsequently, after the lapse of the first predetermined period of time, i.e., at a time t3(seeFIG. 10), the controller50controls the flow rate controller207and the valve208to discharge the third gas into the processing chamber4through the gas discharge holes12aof the shower housing11, thus starting to supply the third gas into the processing chamber4(in step S206). In this embodiment, the third gas is, e.g., an SiF4gas. The controller50controls the flow rate controller207such that a flow rate of the third gas is, e.g., 5 sccm. Further, for example, the controller50reduces the flow rate of the second gas by the flow rate of the third gas such that the sum of the flow rates of the first to third gases is uniform. That is to say, the flow rate of the second gas is reduced from 36 sccm to 31 sccm, as shown inFIG. 10, for example.

Thus, the plasma generated within the processing chamber4leads to the disassociation of the first to third gases, and film-forming species generated by the disassociation start to be deposited on the first film107formed in step S205to cover the first film107. The controller50waits for a second predetermined period of time until the second film108having the thickness d2is stacked on the first film107by the deposition of the film-forming species (in step S207).

Subsequently, after the lapse of the second predetermined period of time, i.e., at a time t4(seeFIG. 10), the controller50controls the valve208to stop the supply of the third gas into the processing chamber4(in step S208). Along with the stop of the supply of the third gas, the controller50returns the flow rate of the second gas to the initial flow rate before the start of the supply of the third gas. That is to say, the flow rate of the second gas is increased from 31 sccm to 36 sccm, as shown inFIG. 10, for example.

Thereafter, the plasma generated within the processing chamber4leads to the disassociation of the first and second gases, and film-forming species generated by the disassociation start to be deposited on the second film108. The controller50waits for a third predetermined period of time until the third film109having the thickness d3is stacked on the second film108by the deposition of the film-forming species (in step S209).

Subsequently, after the lapse of the third predetermined period of time, i.e., at a time t5(seeFIG. 10), the controller50controls the RF power source15and the RF power source29to stop the application of the RF powers, and controls the valve202and the valve205to stop the supply of the first and second gases (in step S210). Also, the controller50controls the exhaust device30to vacuum-exhaust the interior of the processing chamber4through the exhaust pipe31. Thereafter, the gate valve27is opened, and the light emitting module100A is unloaded from the processing chamber4through the opening27a.

So far, the second embodiment has been described. According to the film forming apparatus10of this embodiment, in a case where the fluorine-containing SiN film is used as the sealing film105A, the fluorine-free SiN film is interposed between the organic EL device106and the fluorine-containing SiN film. This configuration prevents the organic EL device106from being damaged by the fluorine. Further, according to the film forming apparatus10of this embodiment, the fluorine-containing SiN film is covered with the fluorine-free SiN film. This prevents the fluorine-containing SiN film from being oxidized by oxygen in the atmosphere, thus suppressing degradation in a moisture-proof property.

Hereinafter, a third embodiment will be described. A sealing film105B of the third embodiment is different from the sealing film105A of the second embodiment in that the sealing film105B of the third embodiment includes a concentration gradient of fluorine applied in a thickness direction in the fluorine-free second film108. Further, a film forming apparatus used in the third embodiment is similar in configuration with the film forming apparatus10of the first embodiment described with reference toFIGS. 1 and 2, and thus, a detailed description thereof will be omitted. Also, an outline of a procedure of manufacturing a light emitting module of the third embodiment is similar in a manufacturing procedure with the light emitting module100of the first embodiment described with reference toFIG. 3, and thus, a detailed description thereof, except for the matters described hereinafter, will be omitted.

[Structure of Light Emitting Module100]

FIG. 11is a cross-sectional view showing an example of a structure of the sealing film105B according to the third embodiment. As shown inFIG. 11, for example, the sealing film105B of this embodiment includes a first film107, a second film108A, and a third film109. As shown inFIG. 11, for example, the second film108A of this embodiment includes a first layer108a, a second layer108b, and a third layer108c.

The first layer108ais formed to have a thickness d4. The first layer108aincludes a concentration gradient in which a concentration of fluorine increases in a thickness direction from the first film107toward the third film109. For example, the concentration of fluorine in the first layer108amonotonously increases from zero to a predetermined concentration. In this embodiment, the predetermined concentration represents that the concentration of fluorine ranges from 4 to 6 atom % (e.g., 5 atom %). The second layer108bis formed to have a thickness d5and contains fluorine of a predetermined concentration. The third layer108cis formed to have a thickness d6and has a concentration gradient in which a concentration of fluorine decreases in the thickness direction from the first film107toward the third film109. For example, the concentration of fluorine in the third layer108cmonotonously decreases from a predetermined concentration to zero.

[Details of Step of Forming Second Film108A]

FIG. 12is a flowchart showing an example of a step of forming the second film108A according to the third embodiment, which corresponds to a series of steps (i.e., S206to S208) of forming the second film105A inFIG. 9.FIG. 13is a view showing an example of a change in flow rate of each process gas included in a mixture gas in the third embodiment.

For example, by the plasma of the first and second gases supplied into the processing chamber4, the film-forming species of the first and second gases are deposited on the organic EL device106, and the first film107having a predetermined thickness is stacked on the organic EL device106at a time t3(seeFIG. 13). Further, for example, at the time t3shown inFIG. 13, along with the start of the supply of the third gas, the controller50controls the flow rate controller204and the flow rate controller207to increase a flow rate of the third gas from zero, while maintaining the sum of flow rates of the second and third gases (in step S220). As shown inFIG. 13, for example, the flow rate of the second gas decreases as the flow rate of the third gas increases. Thus, the first layer108ain which the concentration of fluorine increases with an increase in thickness of the first layer108ais stacked on the first film107.

The controller50waits for a first predetermined period of time until the first layer108aof the thickness d4is stacked on the first film107(in step S221). After the lapse of the first predetermined period of time, the flow rate of the third gas is increased to a predetermined level. The predetermined level represents a flow rate at which the concentration of fluorine in the first layer108aranges from 4 to 6 atom % (e.g., 5 atom %). InFIG. 13, the flow rates of the second and third gases have been shown to be linearly changed, but may be changed in a curved shape or a stepped shape.

Subsequently, after the lapse of the first predetermined period of time, i.e., at a time t31(seeFIG. 13), the controller50controls the flow rate controller204and the flow rate controller207to maintain the flow rate of the third gas at the predetermined level (in step S222). Thus, the second layer108bin which the concentration of fluorine is maintained to a predetermined concentration in the thickness direction is stacked on the first layer108a.

The controller50waits for a second predetermined period of time until the second layer108bof the thickness d5is stacked on the first layer108a(in step S223). After the lapse of the second predetermined period of time, i.e., at a time t32(seeFIG. 13), the controller50controls the flow rate controller204and the flow rate controller207to reduce the flow rate of the third gas from the predetermined level, while maintaining the sum of the flow rates of the second and third gases (in step S224). As shown inFIG. 13, for example, the flow rate of the second gas increases with the decrease in the flow rate of the third gas. Thus, the third layer108cin which the concentration of fluorine decreases with an increase in thickness of the third layer108cis stacked on the second layer108b.

The controller50waits for a third predetermined period of time until the third layer108cof the thickness d6is stacked on the first layer107(in step S225). After the lapse of the third predetermined period of time (i.e., a time t4), the flow rate of the third gas becomes 0 sccm. Subsequently, the controller50controls the valve208to stop the supply of the third gas into the processing chamber4, followed by executing step S209and steps subsequent thereto, which are shown inFIG. 9. In this way, the second film108A shown inFIG. 11is formed.

So far, the third embodiment has been described. According to the film forming apparatus10of this embodiment, the second film108A in which the concentration of fluorine increases toward the center of the second film108A in the thickness direction is formed. Here, since both the first film107and the third film109that are in contact with the second film108A do not contain fluorine, the first film107and the third film109have a film density lower than that of the second film108A. If the second film108A has the concentration gradient of fluorine as described above, stress may be applied to a boundary between the first film107and the second film108A, which have different film densities, and a boundary between the second film108A and the third film109, which have different film densities.

In contrast, in the second film108A of this embodiment, fluorine concentrations in both surfaces which face the first film107and the third film109are close to zero. This reduces the stress to be applied to the boundary between the first film107and the second film108A, and the boundary between the second film108A and the third film109, thus increasing adhesion between the first film107and the second film108A and adhesion between the second film108A and the third film109.

Further, in the second film108A of this embodiment, the concentration of fluorine increases toward the center of the second film108A in the thickness direction of the second film108A. This forms a region having a high film density within the second film108A, thus obtaining a high moisture-proof effect.

Hereinafter, a fourth embodiment will be described. A sealing film of the fourth embodiment is different from the sealing film105A of the second embodiment, in that fluorine-containing second films and fluorine-free first films are alternately stacked. Further, a film forming apparatus used in the fourth embodiment is similar in configuration to the film forming apparatus10of the first embodiment described above with reference toFIGS. 1 and 2, and thus, a detailed description thereof will be omitted. Further, a light emitting module used in the fourth embodiment is similar in a manufacturing procedure to the light emitting module100of the first embodiment described with reference toFIG. 3. Thus, a description of the configuration of the film forming apparatus10and an outline of the manufacturing procedure of the light emitting module100, except for the matters described hereinafter, will be omitted.

FIG. 14is a cross-sectional view showing an example of a structure of the sealing film105C according to the fourth embodiment. As shown inFIG. 14, for example, the sealing film105C of this embodiment has a structure in which a plurality of first films107-1to107-n0and a plurality of second films108-1to108-n0are alternately stacked, and a third film109is stacked on the uppermost layer (i.e., the second film108-n0). In the sealing film105C shown inFIG. 14, the first films107-1to107-n0and the second films108-1to108-n0are alternately stacked n0times.

The first films107-1to107-n0are formed to have a substantially same thickness d7. The second films108-1to108-n0are formed to have a substantially same thickness d8. Also, the thickness d7of each of the first films107-1to107-n0ranges from 0.5 to 1.5 times the thickness d8of each of the second films108-1to108-n0. The third film109is formed to have a thickness d9double or more (e.g., within a range from 2 to 4 times) as large as the thickness d8of each of the second films108-1to108-n0.

In some embodiments, the thickness d7of each of the first films107-1to107-n0may be smaller than the thickness d1of the first film107of the second embodiment. In some embodiments, the thickness d8of each of the second films108-1to108-n0may be smaller than the thickness d2of the second film108of the second embodiment. In some embodiments, the thickness d9of the third film109may be smaller than the thickness d3of the third film109of the second embodiment.

[Details of Sealing Film Forming Process]

FIG. 15is a flowchart showing an example of a process of forming the sealing film105C according to the fourth embodiment. The sealing film forming process according to this embodiment is performed using, e.g., the film forming apparatus10shown inFIG. 1.

First, the controller50receives a constant n0indicating a stack number of alternately stacking the plurality of first films107-1to107-n0and the plurality of second films108-1to108-n0. The controller50also initializes a variable n for counting the stack number to zero (in step S300). Thereafter, the controller50executes a sequence of subsequent steps S301to S305. The sequence of steps S301to S305is similar to a sequence of steps S200to S204described with reference toFIG. 9, and thus, a description thereof will be omitted.

In step S305, plasma generated within the processing chamber4leads to the disassociation of the first and second gases, and film-forming species generated by the disassociation start to be deposited on the organic EL device106formed on the glass substrate G to cover the organic EL device106. The controller50waits for a first predetermined period of time until the first film107-1of the thickness d7is stacked by the deposition of the film-forming species (in step S306).

After the lapse of the first predetermined period of time, the controller50controls the flow rate controller207and the valve208to discharge the third gas into the processing chamber4through the gas discharge holes12aof the shower housing11, thus starting to supply the third gas into the processing chamber4(in step S307). In this embodiment, under the control of the controller50, for example, the flow rate of the third gas (SiF4gas) is adjusted to 5 sccm, and the flow rate of the second gas (SiH4gas) is adjusted to 31 sccm.

Thus, the plasma generated within the processing chamber4leads to the disassociation of the first to third gases, and film-forming species generated by the disassociation start to be deposited on the first film107-1formed in step S305to cover the first film107-1. The controller50waits for a second predetermined period of time until the second film108-1of the thickness d8is stacked on the first film107-1by the deposition of the film-forming species (in step S308).

Subsequently, after the lapse of the second predetermined period of time, the controller50controls the valve208to stop the supply of the third gas into the processing chamber4(in step S309). Along with the stop of the supply of the third gas, the controller50returns the flow rate of the second gas to a level, e.g., 36 sccm, before the start of the supply of the third gas.

Thereafter, the controller50determines whether the variable n has reached the constant n0received in step S300(in step S310). When the variable n has not reached the constant n0(“NO” in S310), the controller50increments the variable n by one (in step S313) and again executes step S306.

Meanwhile, when the variable n has reached the constant n0(“YES” in S310), the controller50waits for a third predetermined period of time until the third film109of the thickness d9is stacked on the uppermost second film108-n0by the plasma of the first and second gases generated within the processing chamber4(in step S311).

Subsequently, after the lapse of the third predetermined period of time, the controller50controls the RF power source15and the RF power source29to stop the application of the RF powers, and controls the valve202and the valve205to stop the supply of the first gas and the second gas (in step S312). Thereafter, the controller50controls the exhaust device30to vacuum-exhaust the interior of the processing chamber4through the exhaust pipe31. And then, the gate valve27is opened, and the light emitting module100is unloaded from the processing chamber4through the opening27a.

So far, the fourth embodiment has been described. According to the film forming apparatus10of this embodiment, in a case where the fluorine-containing SiN film is used as the sealing film105C, the fluorine-containing SiN films and the fluorine-free SiN films are alternately repeatedly stacked. This enhances a trap effect of water molecule, while constraining an additive amount of fluorine.

The present disclosure is not limited to the above embodiments and may be variously modified within the scope of the gist of the present disclosure.

While in the above embodiments, the first gas containing nitrogen or the like has been described to be, e.g., the N2gas, the present disclosure is not limited thereto. In some embodiments, an NH3gas may be used as the first gas.

Further, while in the above embodiments, the third gas containing fluorine or the like has been described to be, e.g., the SiF4gas, the present disclosure is not limited thereto. In some embodiments, an SiHxF4-x(where x is an integer from 1 to 3) such as an SiH3F gas or an SiH2F2gas may be used as the third gas.

Further, while in the above embodiments, the third gas has been described to contain fluorine or the like, the present disclosure is not limited thereto. In some embodiments, the third gas may be a gas containing a halogen element other than fluorine, instead of fluorine, as long as the gas contains the halogen element. Examples of the third gas containing a halogen element may include an SiCl4gas, an SiHxCl4-x(where x is an integer from 1 to 3) gas, an SiHxFyClz(where x, y, and z are natural numbers that satisfy x+y+z=4) gas or the like. Further, by adding a chlorine-containing gas, it is possible to form a hydrogen bond of NH4+. . . Cl−which has a bonding force stronger than that of a hydrogen bond between NH . . . NH.

Further, in the above embodiments, the SiF4gas has been described to be used as the third gas, but in some embodiments, a gas containing a functional group having an electronegative property stronger than that of nitrogen may be used as the third gas. Electrons are easy to adhere to the functional group having a strong electronegative property. Also, like F or Cl element having a strong electronegativity, the functional group having a strong electronegative property is maintained to be electrically negative even in the functional group is decomposed and separated from a gas in plasma within a film, thus easily forming a hydrogen bond. Examples of the functional group having an electronegative property stronger than that of nitrogen may include a carbonyl group, a carboxylate group or the like. When a gas having a function group such as carbonyl group: —C(═O)— or carboxylate group: (R)—COOH is added, the function group is mixed into the SiN film so that a hydrogen bond of NH . . . O═C or a hydrogen bond of NH4+RCOO−stronger than a hydrogen bond between NH . . . NH is formed. This strengthens the hydrogen bond between the SiN particles, which makes it possible to strengthen a connection between the SiN particles in the SiN film, thus further increasing a film density of the SiN film.

Further, while in the second to fourth embodiments, the fluorine-free first film107is installed between the fluorine-containing second film108and the organic EL device106, the present disclosure is not limited thereto. In some embodiments, when a concentration of fluorine in the second film108is low, the first film107may not be formed between the second film108and the organic EL device106. In particular, in a case where a concentration gradient of fluorine is applied such that the concentration of fluorine increases toward the center of the second film108in the thickness direction of the second film108, a concentration of fluorine in each of upper and lower surfaces of the second film108is close to zero. Thus, if the second film108in which the concentration gradient of fluorine is applied is used, even though the second film108is stacked on the organic EL device106, it is possible to lower damage of fluorine contained in the second film108to the organic EL device106.

Further, while in the third embodiment, the second film108A has been described to include the second layer108bhaving a substantially uniform fluorine concentration, which is formed near the center of the second film108in the thickness direction, the present disclosure is not limited thereto. In some embodiments, the second layer108bmay not be formed in the second film108A. In this case, the second film108A includes the first layer108aand the third layer108cin which a concentration of fluorine increases toward the center of the second film108A in the thickness direction. The concentration of fluorine in the first layer108ais increased from zero to a predetermined level toward the center of the second film108A in the thickness direction. Also, the concentration of fluorine in the first layer108cis decreased from the predetermined level to zero as it is away from the center of the second film108A in the thickness direction. Here, the predetermined level refers to a concentration of fluorine ranging from, e.g., 4 to 6 atom % (in some embodiments, 5 atom %).

Further, while in the fourth embodiment, the fluorine-containing second films108-1to108-n0and the fluorine-free first films107-1to107-n0has been described to be alternately stacked and a concentration gradient of fluorine has been described to be not applied in the fluorine-containing second films108-1to108-n0, the present disclosure is not limited thereto. In some embodiments, each of the fluorine-containing second films108-1to108-n0may have a concentration gradient of fluorine such that the concentration of fluorine is increased toward the center of the sealing film105C in the thickness direction. Accordingly, according to the fourth embodiment, it is possible to reduce stress to be applied to respective boundaries between the first films107-1to107-n0and the second films108-1to108-n0, and a boundary between the uppermost second film108-n0and the third film109may be reduced.

In some embodiments, as shown inFIG. 16, a sealing film105D in which fluorine-containing second films108and fluorine-free first films107are alternately stacked n0times may be provided. In the sealing film105D, a concentration of fluorine in each of the second films108may be increased or decreased in a stepwise manner such that the concentration of fluorine in the substantially middle second film108which is stacked at about half of the n0times is maximized. Specifically, when the constant n0indicating the stack number of the first films107and the second films108is an even number, a concentration of fluorine in, e.g., the (n0/2+1)th second film108may be maximized. Also, when the constant n0is an odd number, a concentration of fluorine in, e.g., the ((n0+1)/2)th second film108may be maximized.

Assuming that a second film having the maximum fluorine concentration is the (nx)th second film108, the1st second film108to the (nx−1)th second film108are sequentially stacked from below. Assuming that the maximum fluorine concentration is X, fluorine concentrations of the 1st to (nx−1)th second films108are calculated by sequentially incrementing a value obtained by dividing the concentration X by (nx−1)+1, i.e., by dividing the concentration X into equal parts. And, the 1st to (nx−1)th second films108having the sequentially-incremented fluorine concentrations are stacked in the stepwise manner, respectively.

Meanwhile, the (nx+1)th to (n0)th second films108are sequentially stacked on the (nx)th second film108. As described above, assuming that the maximum fluorine concentration of second film108is X, fluorine concentrations of the (nx+1)th to (n0)th second films108are calculated by sequentially decrementing a value obtained by dividing the concentration X by (n0−nx)+1, i.e., by dividing the concentration X into equal parts. And, the (nx+1)th to (n0)th second film108having the sequentially-decremented fluorine concentrations are stacked in the stepwise manner, respectively.

In the sealing film105D shown inFIG. 16, n0is 7, nxis 4, and X is 5 atom %. In the sealing film105D shown inFIG. 16, the fluorine concentration is set to be incremented by 5/((4−1)+1)=1.25 atom % for n=1 to nx. Further, in the sealing film105D shown inFIG. 16, the fluorine concentration is decremented by 5/((7−4)+1)=1.25 atom % for n=nxto n0.

As described above, in the sealing film105D in which the fluorine-containing second films108and the fluorine-free first films107are alternately stacked, the second films108are formed to have a higher fluorine concentration in a stepwise manner as the second films108are positioned closer to the center of the sealing film105D in the thickness direction of the sealing film105D. This reduces the overall stress of the sealing film105D.

In some embodiments, the sealing film105D shown inFIG. 16may include the second films108having the same thickness or different thicknesses depending on values of fluorine concentrations. Similarly, the first films107may have the same thickness or different thicknesses depending on a value of a fluorine concentration of the respective second film108adjacent thereto.

Further, in some embodiments, each of the second films108included in the sealing film105D shown inFIG. 16may have a fluorine concentration gradient in the thickness direction of the second film108. In this case, for example, as shown inFIG. 17, the fluorine concentration gradient applied to each of the second films108may be set such that a concentration of fluorine is increased toward the center of the second film108in the thickness direction of the second film108. In the example shown inFIG. 17, the fluorine concentrations of the second films108are increased from zero to a predetermined level D from a boundary between the first film107and the second film108toward the vicinity of the center of the second film108in the thickness direction of the second film108. The concentration of fluorine in the vicinity of the center of the second film108is maintained at the predetermined level D. Here, the predetermined level D represents a concentration determined depending on values of n0, nx, and X with respect to the second film108as a target.

In some embodiments, for example, as shown inFIG. 18, the concentration of fluorine in the second film108may be increased from zero to a predetermined level D from a boundary between the first film107and the second film108toward the vicinity of the center of the second film108in the thickness direction of the second film108. Subsequently, he concentration of fluorine may be decreased from the predetermined level D to zero, without maintaining the predetermined level D.

As described above, in the sealing film105D in which the fluorine-containing second films108and the fluorine-free first films107are alternately stacked, the fluorine concentration gradients are applied to each of the second films108such that the concentration of fluorine is increased toward the center of the second film108in the thickness direction of the second film108and such that the concentration of fluorine in each of the second films108positioned in the vicinity of boundaries between the respective first films107and the respective second films108is zero. With this configuration, it is possible to form a layer having a predetermined concentration of fluorine in each of the second films108and reduce stresses between the respective first films107and the respective second films108.

Further, while in the above embodiments, the film forming apparatus10configured to form a film by a CVD method using the inductively-coupled plasma as a plasma source, has been described as an example, the present disclosure is not limited thereto. As an example, as long as the film forming apparatus10forms a film by the CVD method using plasma, a certain plasma source such as a capacitively-coupled plasma, a microwave plasma, or a magnetron plasma may be used.

Further, in the above embodiments, the film forming method which forms the sealing film105(105A,105B,105C or105D) to seal the organic EL device106has been described, but a device sealed by the sealing film105(105A,105B,105C or105D) is not limited to the organic EL device106. The present disclosure may also be applied to a film forming method which forms a film to seal a device such as a semiconductor device, a solar cell device or the like, in addition to the organic EL device106.

According to the present disclosure in some embodiments, it is possible to provide a film forming method and a film forming apparatus, which are capable of forming a sealing film to seal a device such as an organic EL device, the sealing film having a high moisture-proof property and a thin thickness.