Method for manufacturing a barrier layer structure and barrier layer structure

Abstract

To provide a method for manufacturing a silicon nitride-based barrier layer structure having high barrier property by irradiating a polysilazane compound with ultraviolet light having a wavelength of 230 nm or less, and to provide a barrier layer structure.SOLUTION: A method for manufacturing a barrier layer structure includes: a step 1 of applying or printing a solution including a polysilazane compound comprising Si-N as a principal skeleton on an object; and a step 2 of irradiating the polysilazane compound on the object with ultraviolet light having a wavelength of 230 nm or less under a nitrogen atmosphere to form a silicon nitride-based layer.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a method for producing a silicon nitride-based barrier layer structure by irradiating a polysilazane compound with vacuum ultraviolet light, and to the barrier layer structure itself. [Background technology]

[0002] Gas barrier films are used in a wide range of fields, including packaging and electronics. Electronic products, in particular, require high barrier performance against water vapor. The indicator of water vapor barrier performance is the water vapor transmission rate (WVTR), and for semiconductor devices such as organic EL elements and solar cells, a water vapor transmission rate of 10 is required. -3 ~10 -6 g / m 2 A barrier performance of / day is required.

[0003] Inorganic barrier films fabricated using vacuum processes such as atomic layer deposition (ALD) and chemical vapor deposition (CVD) achieve very low water vapor permeability. Furthermore, barrier structures with an alternating inorganic / organic layer structure, where a polymer is introduced as a stress-relaxing layer to alleviate stress in the inorganic barrier film, have also been proposed. However, vacuum processes have low material utilization efficiency and problems such as the adhesion of foreign matter due to repeated processes with atmospheric pressure / vacuum pressure differences. Also, the film deposition rate is slower compared to wet processes. In alternating layer structures, polymers are generally fabricated by coating, requiring alternating vacuum and coating processes, which increases manufacturing costs.

[0004] On the other hand, gas barrier layers fabricated using a wet process to create a stress relaxation layer and an inorganic barrier film have also been reported. The all-solution process can achieve high resource efficiency and high processing capacity (throughput), while keeping manufacturing costs low. However, the water vapor permeability of films produced using the all-solution process, such as the common sol-gel method, is 3-350 g / m². 2 / day, and its tightness and barrier properties are lower than those of the vacuum process.

[0005] In the formation of a barrier film by a vacuum process, a problem is that the throughput such as the film formation rate is low. Therefore, a film formation method combining a vacuum process and a wet process using perhydropolysilazane (PHPS) has been studied. Perhydropolysilazane (PHPS) is a reactive polymer having a Si-N bond as a main skeleton, and film formation by a wet process such as coating is possible. When heated in the air, it is converted into a SiO2 film by an oxidation reaction with oxygen, but it can also be converted into a SiO2 film by irradiating with vacuum ultraviolet light (VUV) in the air without heating. The barrier property of the SiO2 film obtained from perhydropolysilazane is 10 -1 ~10 -2 g / m 2 / day, and depending on the production conditions, the water vapor permeability can be reduced to about 10 -3 g / m 2 / day.

[0006] However, the barrier property of the SiO2 film is low, and it is difficult to apply it to electronics sensitive to water vapor. Perhydropolysilazane can be converted into a silicon nitride (Si3N4)-based film by irradiating with vacuum ultraviolet light in a nitrogen atmosphere. Therefore, the present inventors reported that a silicon nitride-based film having a high water vapor barrier property can be obtained by irradiating and curing a perhydropolysilazane (PHPS) film coated by a wet process with vacuum ultraviolet light (VUV) in a nitrogen atmosphere (Non-Patent Document 1).

[0007] In Non-Patent Document 1, a gas barrier layer produced by an all-solution process using polydimethylsiloxane (PDMS) having a Si-O bond as a main skeleton for a stress relaxation layer and perhydropolysilazane (PHPS) for a barrier layer is reported, and the water vapor permeability has reached 10 -3 g / m 2 / day.

Prior Art Documents

Non-Patent Documents

[0008]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] This low water vapor permeability is achieved by densification by irradiation with vacuum ultraviolet light (VUV). However, due to the short penetration length of vacuum ultraviolet light into the perhydropolysilazane film, there is a distribution in the densification of the perhydropolysilazane film after vacuum ultraviolet light treatment. Compared with the density inside the perhydropolysilazane film, the vicinity of the surface about 90 nm from the substrate is very dense. When the perhydropolysilazane film is irradiated with vacuum ultraviolet light, not only Si-H bonds and N-H bonds are broken, but also the porosity decreases and densification progresses due to atomic rearrangement by repeated cleavage-recombination of the Si-N bonds in the main chain.

[0010] Therefore, an object of the present invention is to provide a method for uniformly densifying a film and forming a barrier layer structure by adjusting the wavelength and irradiation amount of vacuum ultraviolet light. Excellent water vapor transmission rate (water vapor permeability)

Means for Solving the Problems

Means for Solving the Problems

[0011] The present invention consists of the following. [1] Step 1 of applying or printing a solution containing a polysilazane compound having Si-N as a main skeleton to an object, under a nitrogen atmosphere, Vacuum ultraviolet light with wavelengths of 100-190 nm irradiating the polysilazane compound on the object to form a silicon nitride-based layer in Step 2 、 It has, The integrated amount of the vacuum ultraviolet light irradiated is 6000 to 24000 mJ / cm². 2 And, The thickness of the barrier layer structure is 112 to 250 nm.A method for manufacturing a barrier layer structure characterized by the above. [2] The method for producing a barrier layer structure according to claim 1, characterized in that the polysilazane compound is a perhydropolysilazane (PHPS). [3] Vacuum ultraviolet light with wavelengths of 100-190 nm After irradiation, Further irradiation with ultraviolet light at a wavelength of 200-230 nm. do features 1 A method for manufacturing the barrier layer structure described above. [4] The method for manufacturing a barrier layer structure according to claim 1, further comprising step 3, in addition to steps 1 and 2, step 3, of applying or printing a solution containing at least one selected from ultraviolet-curable polysiloxane, acrylic resin, and epoxy resin onto a silicon nitride-based film on an object, and curing it with light or heat to form a resin layer.

[0012] [5] The process is characterized by performing steps 1 to 3 in this order multiple times, thereby alternately laminating the silicon nitride-based layer and the resin layer. [4] A method for manufacturing the barrier layer structure described above. [6] In step 2, ultraviolet light with a wavelength of 230 nm or less is irradiated at a temperature of 15 to 40°C. [1] A method for manufacturing the barrier layer structure described above. [7] Prior to step 1, the object is characterized by surface modification by vacuum ultraviolet light or UV ozone cleaning. [1] A method for manufacturing the barrier layer structure described above. A barrier structure of a silicon nitride-based layer formed on an object by a method for manufacturing a barrier layer structure described in [8] [1], wherein the thickness of the silicon nitride-based layer structure is 112 to 250 nm and the water vapor transmission rate is 2.6 × 10 -3 g / m 2 It must be less than or equal to / day A distinctive barrier layer structure. [9] The barrier layer structure according to [8], characterized in that the silicon nitride layer is free of cracks when observed with a scanning electron microscope. [Effects of the Invention]

[0013] According to the present invention, a solution containing a polysilazane compound is applied or printed onto an object, and under a nitrogen atmosphere, vacuum ultraviolet light with a wavelength of 100-190 nm is irradiated, and 6000-24000 m J / cm 2 By irradiating the polysilazane compound coating with the integrated light intensity, Excellent water vapor transmission rate (water vapor permeability) A silicon nitride-based barrier layer structure with barrier properties can be obtained. Vacuum ultraviolet light with wavelengths of 100 to 190 nm is mostly absorbed at the layer surface, resulting in a higher density on the surface compared to the interior of the layer. However, further irradiation with ultraviolet light with wavelengths of 200 to 230 nm increases the density of the interior of the layer, resulting in a barrier layer structure with uniform density throughout the entire layer structure. According to the present invention, a high-purity silicon coating material of the coating type using a polysilazane compound can be provided. [Brief explanation of the drawing]

[0014] [Figure 1] Figure 1 is a bar graph showing the relationship between PHPS film thickness, VUV integrated light intensity, and barrier performance. [Figure 2] Figure 2(a) shows the refractive index distribution (in the direction of film thickness) when a PHPS film with a thickness of approximately 350 nm is irradiated with VUV light, Figure 2(b) shows the relationship between the VUV integrated light intensity and WVTR at a PHPS film thickness of 200 nm, and Figure 2(c) shows the relationship between the PHPS film thickness and WVTR at a VUV integrated light intensity of 12,000 mJ / cm2. [Figure 3] Figure 3 shows SEM images of cracks and delaminations, along with water vapor transmission rates, under typical conditions.

[0015] [Figure 4] Figure 4 shows the refractive index distribution obtained by spectroscopic ellipsometry when irradiated with an excimer lamp with a wavelength of 222 nm. [Figure 5] Figure 5 shows the refractive index distribution obtained by spectroscopic ellipsometry when irradiated with an excimer lamp with a wavelength of 172 nm. [Figure 6] Figure 6 shows the refractive index distribution after irradiation with light of wavelength 222 nm (6,000 mJ / cm2) following irradiation with light of wavelength 172 nm. [Figure 7] Figure 7 shows the water wettability of PDMS surfaces obtained under processes in air and nitrogen, expressed as the contact angle. [Figure 8] Figure 8 shows the refractive index distribution of the PHPS layer when wet coating was performed under nitrogen and atmospheric conditions. [Figure 9] Figure 9 shows the emission curve of an organic EL element stored at 60°C / 90%RH (magnification 50x, field of view 2mm x 1.5mm). [Figure 10] Figure 10 shows the layer structure of the organic EL element fabricated in Example 4. [Modes for carrying out the invention]

[0016] The present invention provides a method for manufacturing a barrier layer structure comprising: step 1, applying or printing a solution containing a polysilazane compound with a Si-N main skeleton onto an object; and irradiating the polysilazane compound on the object with ultraviolet light of a wavelength of 230 nm or less under a nitrogen atmosphere, thereby reducing silicon nitride (Si x N y The process includes step 2 of forming a system layer.

[0017] In step 1, a solution containing a polysilazane compound with a Si-N main skeleton is applied or printed onto the object. Polysilazane compounds include organopolysilazanes such as hexamethyldisilazane (HMDS), as well as perhydropolysilazanes (PHPS) or their modified forms. Of these, perhydropolysilazanes (PHPS) or their modified forms, which have repeating units represented by -SiH2-NH-, are preferred. The number-average molecular weight of polysilazane compounds is usually between 100 and 50,000. Perhydropolysilazanes can be linear, cyclic, or have all of these structures simultaneously within the molecule, and can be used alone or in mixtures of two or more. Perhydropolysilazanes (PHPS) are used as surface treatment agents in the manufacturing process of semiconductor silicon wafers, modifying the silicon wafer surface to be hydrophobic, thereby removing moisture and improving the adhesion of photoresists.

[0018] In the present invention, a solution containing the polysilazane compound described above is coated onto a suitable object, and the formed film is then irradiated with ultraviolet light with a wavelength of 230 nm or less. Solvents for dissolving polysilazane compounds include, for example, aromatic compounds such as benzene, toluene, xylene, ethylbenzene, diethylbenzene, trimethylbenzene, and triethylbenzene; linear hydrocarbon compounds such as pentane, 2-methylbutane, hexane, 2-methylpentane, heptane, 2-methylhexane, octane, 2,2,4-trimethylpentane, nonane, decane, and 2-methylnonane; cyclic hydrocarbon compounds such as ethylcyclohexane, methylcyclohexane, cyclohexane, p-menthane, decahydronaphthalene, and dipentene; ethers such as dipropyl ether, dibutyl ether (DBE), and methyl-t-butyl ether (MTBE); and ketones such as methyl isobutyl ketone (MIBK). These may be used individually or in mixtures of two or more to adjust the evaporation rate of the solvent.

[0019] The concentration of the polysilazane compound solution is typically 5–95% by weight, preferably 5–20% by weight. The solution of the polysilazane compound may contain additives such as fillers, leveling agents, antistatic agents, and ultraviolet absorbers, to the extent that they do not impair the effects of the present invention. The amount of filler added is usually 0.05 to 10 parts by weight, preferably 0.2 to 3 parts by weight, per 1 part by weight of the polysilazane compound.

[0020] While there are no particular limitations on the materials used, those with moisture permeability are often selected from a barrier perspective. Examples include polyimide (PI), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethylene (PE), and polycarbonate (PC). Alternatively, depending on the application, a thin-film glass with a thickness of approximately 10 to 150 μm may be used. The thin-film glass may be used alone, or it may be a thin-film glass with a metal foil such as aluminum foil or a resin film laminated or attached to it. Metal foils such as stainless steel foil, aluminum foil, or copper foil may also be used.

[0021] The method for coating an object with a polysilazane compound solution may be either coating or printing. Examples of coating or printing methods include spin coating, roll coating, flow coating, inkjet, spray coating, dip coating, casting, bar coating, die coating, gravure printing, and screen printing. Degreasing or cleaning the surface of the object before coating or printing will improve the adhesion of the polysilazane compound. Coating or printing may be carried out at room temperature under an inert atmosphere such as nitrogen, or under open air. The ability to perform the process at room temperature and under open air, without the need for a sealed inert gas atmosphere, leads to labor savings and lower costs.

[0022] Prior to step 1, the substrate may be surface-modified by vacuum ultraviolet light or ultraviolet light ozone cleaning. Reactive oxygen species separated from the ozone generated by vacuum ultraviolet light or ultraviolet light collide with the substrate surface, decomposing and removing organic contaminants on the surface. Substrates surface-modified by ozone cleaning have improved wettability, making it easier to apply or print the polysilazane solution. Furthermore, even with vacuum ultraviolet light or ultraviolet irradiation in the absence of oxygen, the decomposition of organic matter adhering to the substrate surface improves the wettability of the substrate, making it easier to print and coat.

[0023] In step 2, ultraviolet (UV) light with a wavelength of 230 nm or less is irradiated onto the polysilazane compound on the object under a nitrogen atmosphere to form silicon nitride. When ultraviolet light is irradiated under atmospheric conditions, silicon(IV) oxide is formed instead of silicon nitride.

[0024] The cumulative amount of ultraviolet light irradiated is 6000 to 24000. mJ / cm 2Preferably, 10,000 to 15,000 mJ / cm 2 This is more preferable. Integrated light intensity (mJ / cm 2 ) is ultraviolet intensity (mW / cm²). 2 It can be calculated by multiplying the curing time (sec) by the time of curing. Furthermore, step 2 can be carried out at room temperature (generally 15-40°C). For example, it can be carried out under heating at 100-120°C, but the same effect can be obtained at room temperature.

[0025] Ultraviolet (UV) light with a wavelength of 230 nm or less specifically refers to vacuum ultraviolet (VUV) light with a wavelength of 100-190 nm. Irradiation with vacuum ultraviolet (VUV) light with a wavelength of 100-190 nm is usually performed using a commercially available excimer lamp (wavelength 172 nm).

[0026] In this invention, it is preferable to apply a polysilazane compound solution to the object, irradiate it with vacuum ultraviolet (VUV) light with a wavelength of 100 to 190 nm, and then irradiate it with ultraviolet light with a wavelength of 200 to 230 nm. Irradiation with vacuum ultraviolet (VUV) light with a wavelength of 100 to 190 nm promotes SiNization in the portion of the coated film near the surface, resulting in densification. At this time, the refractive index of the portion of the barrier layer near the surface becomes 1.6 to 1.9, preferably 1.65 to 1.76, and the refractive index of the portion of the barrier layer near the object becomes 1.50 to 1.6, preferably 1.50 to 1.54. In other words, the density differs between the interior of the SiN barrier layer near the object and the portion near the surface. The refractive index can be determined by spectroscopic ellipsometry. The refractive index distribution is the value in a four-layer analysis model including a thin SiO2 layer formed on the surface.

[0027] On the other hand, if vacuum ultraviolet (VUV) light with a wavelength of 100-190 nm is irradiated followed by ultraviolet light with a wavelength of 200-230 nm, the light penetrates to the interior. This is because ultraviolet light in the 200-230 nm range has a low absorption coefficient for polysilazane, allowing it to penetrate to the interior and trigger a SiN conversion reaction. As a result, SiN conversion progresses inside the coated film, densifying it, and the entire coated film becomes uniformly SiN-converted, resulting in an overall refractive index of 1.6-1.9. In this invention, by using vacuum ultraviolet (VUV) light with a wavelength of 100-190 nm and ultraviolet light with a wavelength of 200-230 nm in combination, and irradiating with each one to several times, it is possible to form a high-density barrier layer structure from the film surface to the interior. Irradiation with ultraviolet light with a wavelength of 200-230 nm is usually performed using a commercially available excimer lamp (wavelength 222 nm).

[0028] In the method for manufacturing the barrier layer structure of the present invention, it is preferable to further include, in addition to steps 1 and 2, step 3, a step in which a solution containing at least one resin selected from curable polysiloxane, acrylic resin, and epoxy resin is applied or printed onto a silicon nitride-based coating on an object, and cured by light or heat.

[0029] The curable polysiloxane is a silicone resin, and polydimethylsiloxane (PDMS) is particularly preferred, although modified PDMS may also be used. UV-curable PDMS is also preferred. UV-curable PDMS generally has high viscosity and may be diluted with a low-molecular-weight siloxane. Examples of low-molecular-weight siloxanes are cyclic or linear siloxanes having 4 to 20 silicon atoms. The UV-curable polysiloxane is not particularly limited as long as it cures with UV irradiation, and may, for example, be a compound having acrylic groups at both ends of the siloxane chain. Commercially available products include, for example, cyclic octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), dodecamethylcyclohexasiloxane (D6), tetradecamethylcycloheptasiloxane (D7), and linear siloxanes (L4 to L14) (all manufactured by Shin-Etsu Chemical Co., Ltd.). Low-molecular-weight siloxanes with high boiling points form a silicone gel when coexisting with PDMS. This allows for adjustment of strength and softness.

[0030] The formation of this resin layer can be carried out under either a nitrogen or atmospheric environment, but it is preferable to do so under atmospheric conditions. This is because the resin layer formed under atmospheric conditions has significantly lower water wettability as measured by a contact angle meter (Figure 7) compared to the resin layer formed under nitrogen conditions, making it easier to wet-coat with polysilazane compound solutions. Furthermore, performing the process under atmospheric conditions is also more cost-effective.

[0031] In a preferred embodiment of the present invention, the barrier structure is formed by applying or printing a solution of UV-curable polysiloxane, acrylic resin, or epoxy resin dissolved in an organic solvent before or after forming the SiN layer, and then curing it with light or heat to form a resin layer above or below the SiN layer. By forming a resin layer above or below the SiN layer, the stress on the barrier layer is relieved, preventing the generation of strain and suppressing the rupture of the barrier layer.

[0032] Steps 1 to 3 described above may be performed in this order one or more times, and the silicon nitride-based film and the resin film may be alternately laminated. If a layer consisting of a SiN layer and a resin layer is considered as one unit, even one unit is sufficient to exert a stress relaxation effect, but about five units are also acceptable, and about one to three units are more preferable. The film thickness of the barrier layer structure is preferably 150 to 250 nm, and more preferably 200 to 250 nm.

[0033] When using an excimer lamp with a wavelength of 172 nm, preferably a combination of excimer lamps with wavelengths of 172 nm and 222 nm, the irradiation time depends on the intensity of the excimer lamps used, but for example, when the target object is exposed to 85 mW / cm². 2 When using an excimer lamp capable of irradiation, the irradiation time is 1 to 3 minutes per barrier layer. With 3 units, it is 3 to 9 minutes. Non-patent document 1 states that an irradiation time of 5 minutes per PHPS barrier layer is required, and 10 -3 g / m 2 The three units that achieved the / day target required a total processing time of 15 minutes.

[0034] The barrier layer structure of the present invention is formed on an object, and the refractive index of the portion of the barrier layer close to the outer surface is 1.6 to 1.9, preferably 1.65 to 1.76, and the refractive index of the portion of the barrier layer close to the object is 1.50 to 1.6, preferably 1.50 to 1.54. The water vapor transmission rate (WVTR) of the barrier layer structure of the present invention is 2.6×10 -3 g / m 2 / day or less And conventionally, 3 × 10 -3 g / m 2 The barrier performance, which was about / day Further improvement Water vapor transmission rate (WVTR) is calculated based on the unit time (1 day) and unit area (m²). 2 This is the amount of water vapor (g) per unit.

[0035] It is presumed that the important parameters determining the barrier performance of the barrier layer structure of the present invention are the film thickness and the VUV irradiation dose. As shown in Figure 1, the barrier layer structure has a film thickness of 200-250 nm and an integrated light dose of 6000-12000 mJ / cm 2 The water vapor transmission rate (WVTR) is lowest at this cumulative light intensity. [Examples]

[0036] The present invention will be described in more detail below based on examples, but the present invention is not limited to the following examples.

[0037] [Example 1] <Measuring refractive index> A 20 wt% dibutyl ether (DBE) solution of perhydropolysilazane (PHPS) (manufactured by Shin-Etsu Chemical Co., Ltd.) was deposited on a cleaned silicon wafer by spin coating. As shown in Table 1, the film thickness was controlled by adjusting the solution concentration and spin coating rotation speed (Experimental Examples 1-24). Solution preparation and spin coating were performed in a glove box filled with nitrogen (water and oxygen concentrations <10 ppm). Furthermore, a 172 nm vacuum ultraviolet (VUV) light under nitrogen was irradiated using an excimer lamp installed in the glove box to form a photodensified PHPS layer on the silicon wafer. The excimer lamp used was a FLAT EXCIMER (irradiation intensity 20 mW / cm²) manufactured by Hamamatsu Photonics K.K. 2 ) or MEIRHA-MS-1-152-H manufactured by M.D. Com Co., Ltd. (irradiation intensity 85mW / cm²) 2 The VUV irradiation dose was calculated using an ultraviolet integrated light meter (Hamamatsu Photonics K.K. C9536-sensor head H9535-172). The refractive index distribution in the film thickness direction of the photodensified PHPS layer on a silicon wafer was measured using spectroscopic ellipsometry (VASE32, manufactured by J.A. Woo-Lam Japan Co., Ltd.). In the ellipsometry measurements, the angle of incident light was varied in 5° increments from 45° to 75°. The polarization state of the light, represented by experimental ellipsometric parameters (Ψ and Δ), was analyzed using a four-layer optical model including SiO2 and three single-layer models including a Gaussian oscillator. For refractive index measurements, in order to precisely measure the refractive index of the photodensified polysilazane layer that serves as the barrier layer (SiN layer), only one polysilazane layer was coated onto the silicon wafer before measurement.

[0038] <Fabrication of barrier films and measurement of barrier performance> On a polyimide film (PI film: Xenomax, Ra: ~0.5nm, thickness: 38μm, sample size: 50mm x 50mm, manufactured by Xenomax Japan Co., Ltd.), a stress relaxation layer was prepared by mixing an oligomer of UV-curable polydimethylsiloxane (PDMS), a crosslinking agent (X-34-4184 A and B, manufactured by Shin-Etsu Chemical Co., Ltd.), and low molecular weight cyclic decamethylcyclopentasiloxane (D5) (manufactured by Shin-Etsu Chemical Co., Ltd.) in a ratio of oligomer:crosslinking agent:D5 = 1:1:16 (by weight) using a rotary-orbit mixer (2000 rpm, 4 minutes) to prepare a PDMS-D5 solution. The PDMS-D5 solution was spin-coated onto the polyimide film under a nitrogen atmosphere in a glove box at 6000 rpm for 30 seconds, and the UV-curable PDMS layer was cured by irradiating it with UV light for 1 minute using a high-pressure mercury lamp. Subsequently, the PDMS surface was irradiated with VUV light under nitrogen for 3 minutes to convert it to SiO2, forming a PDMS cured layer with a thickness of approximately 150 nm. A 20 wt% PHPS DBE solution was spin-coated onto a PDMS cured layer under nitrogen, and then irradiated with VUV light to obtain a PHPS cured layer that would serve as a barrier layer. The method for forming the PHPS cured layer was the same as that used for the PHPS coating in the <Measurement of Refractive Index> section. The performance of the barrier layer formed on the polyimide film and PDMS cured layer was evaluated using a gas permeability measuring device (Super-Detect, manufactured by MORESCO Corporation). The measurement conditions were 40°C / 90%RH. For performance evaluation of the barrier layer, the water vapor permeability (WVTR) of the barrier layer structure was defined as the value at which the water vapor permeability reached a steady state after setting the sample.

[0039] <Observation of the barrier film surface> The surface of the barrier layer structure was observed using a scanning electron microscope (SEM) (JEOL Ltd. JSM-IT100). To prevent static electricity buildup, a thin layer (<2 nm) of Pt was coated onto the surface of the barrier layer using an ion coater. The results are shown in Table 1.

[0040] [Table 1] In Table 1, the PHPS film thickness (nm) is the total thickness determined by spectroscopic ellipsometry. VUV integrated light intensity (mJ / cm²) 2 The value was calculated by multiplying the VUV light intensity by the time. Barrier performance (WVTR) is the water vapor transmission rate at 40°C / 90%RH. Barrier performance is ~10 -4 g / m 2 Let / day be ○, ~10 -3 g / m 2 Let / day be represented as △, and >10 -2 g / m 2 / day was marked with an X. The refractive index (MAX) represents the highest refractive index obtained in the 4-layer model obtained by spectroscopic ellipsometry. Since refractive index correlates with density for the same composition, a higher refractive index indicates higher density. The presence or absence of cracks is shown based on observations using a scanning electron microscope (SEM). The absence of cracks indicates that the material is less permeable to water vapor.

[0041] Figure 1 shows a three-dimensional bar graph summarizing the results of Experimental Examples 1-24. The X and Y axes represent the film thickness of the PHPS (nm) and the integrated VUV light intensity (mJ). / cm 2 ) and the Z axis represents the water vapor transmission rate WVTR (g / m³). 2 It is / day).

[0042] Water vapor transmission rate (WVTR) (g / m³) 2 The smaller the value of / day, the higher the barrier performance. As shown in Figure 1, the highest barrier performance is observed when the PHPS film thickness is 200-250 nm and the VUV integrated light intensity is 12,000 mJ / cm². 2 It can be seen that this is the time. At this time, the barrier performance is 2 × 10 -4 g / m 2 It is / day.

[0043] This reason was revealed through various analyses. Figure 2(a) shows the refractive index distribution (in the direction of film thickness) when a PHPS film with a thickness of approximately 350 nm is irradiated with VUV light. While PHPS densification normally occurs continuously due to VUV light absorption, to obtain high-precision refractive index and film thickness measurements, the barrier layer was divided into four layers, and fitting was performed across these four layers. Figure 2(a) shows the average refractive index and film thickness of each layer. Furthermore, SIMS analysis revealed that an SiO2 layer is formed at the outermost layer; therefore, the outermost layer was fitted as an SiO2 layer.

[0044] Irradiation with VUV light improved the refractive index, particularly at the surface (Top). The refractive index increased from 1.54 without irradiation to 72,000 mJ / cm². 2 The refractive index improved to 1.76 with VUV light irradiation. This improvement in refractive index indicates an increase in density. Furthermore, although not as significant as in the top layer, the refractive index also improved in the mid-layer, which is located in the middle of the barrier layer. (72,000 mJ / cm²) 2 The refractive index improved to 1.65 upon irradiation. On the other hand, almost no improvement in refractive index was observed in the Bot layer on the surface of the silicon substrate. This indicates that VUV light (λ=172nm) is absorbed in the surface layer, and therefore does not reach the Bot layer.

[0045] Here, we focus on the film thickness of the Top and Mid layers, which improve the refractive index. The total film thickness of the Top and Mid layers is 160-170 nm. Figure 2(c) shows the VUV integrated light intensity of 12,000 mJ / cm². 2 This graph shows the relationship between PHPS film thickness and WVTR. As is clear from this graph, high barrier performance cannot be obtained when the film thickness is 150 nm or less. This is thought to be because the PHPS film thickness for high density is 160-170 nm, and therefore the film thickness is insufficient. From the graph in Figure 2(c), it can be seen that the film thickness at which the best performance is obtained is around 200 nm.

[0046] On the other hand, since the refractive index (density) increases as the VUV integrated light intensity increases, the barrier performance is expected to increase monotonically. Figure 2(b) shows the relationship between VUV integrated light intensity and WVTR at a PHPS film thickness of 200 nm. The VUV integrated light intensity is 12,000 mJ / cm². 2 It was found that further irradiation beyond a certain point reduces the barrier's performance.

[0047] To clarify the reason, surface observation was performed using a scanning electron microscope (SEM). Representative results are shown in Figure 3. Regions (iii~v) in Figure 3 correspond to i~v in Figure 1. As can be seen from the SEM images, cracks or delamination occurred on the surface. Although it varies depending on the conditions, it can be seen that the crack width and delamination size correlate with the water vapor transmission rate (WVTR). In other words, when the crack width or delamination size is large, water vapor penetrates through it, resulting in low barrier performance. Table 1 only lists the presence or absence of cracks. When the crack width is small, the decrease in barrier performance is small, so in order to obtain high barrier performance, it is necessary to create a barrier layer structure without cracks.

[0048] The reason these cracks and delaminations occur is due to the photocatalytic reaction of PHPS. The VUV photocatalytic reaction of PHPS is shown below. VUV light causes photocleavage of Si-H and NH in PHPS, and hydrogen is removed. In other words, the VUV photocatalytic reaction of PHPS is a volume contraction system. Irradiation with VUV light promotes the densification of PHPS, but at the same time, internal stress is generated and increases. Therefore, it is thought that cracks occur under strong irradiation conditions. Cracks also depend on the film thickness and adhesion to the underlying layer. In particular, under the condition of a thick film with a film thickness of 500 nm, the VUV light does not reach the interface with the underlying layer, resulting in low adhesion. In addition, the varying magnitudes of stress within the PHPS layer likely created conditions that made cracks more likely to occur.

[0049] [ka] Based on these findings, the PHPS layer thickness is 200-250 nm, and the VUV integrated light intensity is 12,000 mJ / cm². 2 It was determined that the surrounding area has optimal barrier properties.

[0050] [Example 2] As a VUV irradiation source, a 222nm excimer lamp was used in conjunction with a 172nm excimer lamp to perform refractive index measurements and surface observation. The apparatus used was a MEIRHA-MS-1-152-H manufactured by M.D. Com Co., Ltd., which is equipped with both 172nm and 222nm lamps. Otherwise, the procedure was the same as in Example 1. The refractive index distribution results obtained by spectroscopic ellipsometry are shown in Figure 4 for 222nm irradiation and in Figure 5 for 172nm irradiation.

[0051] Figures 4 and 5 show that, compared to 172nm irradiation, 222nm irradiation improves the refractive index of the central (mid) layer of the PHPS. This indicates a significant impact on the absorbance at each wavelength. Specifically, because the absorbance at 222nm is lower than that at 172nm, light is not absorbed at the surface, allowing it to penetrate deeper and increase density. By combining 172nm and 222nm light sources, it becomes possible to increase density even within the film.

[0052] Therefore, after irradiation with 172nm light, the sample was irradiated with 222nm light. The results are shown in Figure 6. From Figure 6, it can be seen that a structure with equally high refractive indices in the top and mid layers can be fabricated. Furthermore, no cracks were found in SEM observation of this sample, suggesting that high barrier performance is achieved.

[0053] [Example 3] In Examples 1 and 2, a PDMS layer (stress relaxation layer) and a PHPS layer (barrier layer) were spin-coated in a glove box under nitrogen, followed by VUV light irradiation. In Example 3, the PDMS layer was formed entirely under atmospheric conditions (in the presence of oxygen and water vapor), while the PHPS layer was formed using a wet-coat process under atmospheric conditions and a VUV light irradiation process under nitrogen. A PDMS-D5 solution was prepared by mixing an oligomer of UV-curable polydimethylsiloxane (PDMS), a stress-relaxing layer, a crosslinking agent (X-34-4184 A and B, manufactured by Shin-Etsu Chemical Co., Ltd.), and low molecular weight cyclic decamethylcyclopentasiloxane (D5) (manufactured by Shin-Etsu Chemical Co., Ltd.) in a ratio of oligomer:crosslinking agent:D5 = 1:1:16 (by weight) using a rotary-orbit mixer (2000 rpm, 4 minutes). The PDMS-D5 solution was spin-coated onto a substrate at 6000 rpm for 30 seconds in air or nitrogen, and the resulting film was irradiated with UV light from a high-pressure mercury lamp for 1 minute to cure the UV-curable PDMS layer. Subsequently, it was irradiated with VUV light in air or under nitrogen for 3 minutes.

[0054] Table 2 shows the refractive index and film thickness under each process condition, as measured by spectroscopic ellipsometry. No refractive index distribution similar to that observed in PHPS was observed in the PDMS layer. From Table 2, no significant difference in refractive index or film thickness was observed between wet process conditions (wet coat / UV curing) and VUV conditions, even when performed in an atmosphere containing oxygen and water vapor. The atmospheric conditions were measured in a cleanroom at 25°C and 50% humidity. [Table 2]

[0055] Furthermore, the water wettability of the PDMS surface obtained under processes in air and nitrogen was measured using a contact angle meter (Figure 7). It can be seen that the water contact angle was significantly smaller and the surface free energy was larger under the air process. This indicates that wet coating of the upper PHPS layer is easier. Easier wet coating of the upper PHPS layer leads to the suppression of pinholes that could not be coated by the PHPS layer, thus enabling the achievement of high barrier performance.

[0056] Here, since PHPS is a polymer with Si-N bonds in its main chain, it reacts with oxygen and water vapor in the atmosphere to form SiO2. It is also known that SiO2 formation occurs quite rapidly when VUV light irradiation is performed under atmospheric conditions. Therefore, we investigated whether it is possible to perform only the wet coating of PHPS under atmospheric conditions and the VUV light irradiation under nitrogen conditions. The results are shown in Figure 8. The refractive index of PHPS remained unchanged when coated under atmospheric and nitrogen conditions. The ellipsometry measurements were performed within 15 minutes. In other words, although PHPS is a reactive polymer that reacts with oxygen and water vapor in the atmosphere, oxidation does not occur in the short term, and it is stable. Furthermore, both PHPS thin films coated under atmospheric and nitrogen conditions were subjected to VUV irradiation under nitrogen. As a result, there was almost no difference in the refractive index distribution in the four-layer model. From this, as mentioned above, it was shown that PHPS is stable for short periods of time, and even if water vapor or oxygen is adsorbed on the surface, it has almost no effect on the film quality.

[0057] In summary, it can be seen that in this invention, all processes may be carried out under nitrogen, or all processes except the VUV light irradiation process may be carried out under low-cost atmospheric conditions.

[0058] [Example 4] In Examples 1-3, the wet-coating conditions for the PDMS layer involved using a solution of UV-curable polydimethylsiloxane (PDMS) oligomer, a crosslinking agent (X-34-4184 A and B, manufactured by Shin-Etsu Chemical Co., Ltd.), and low molecular weight cyclic decamethylcyclopentasiloxane (D5) (manufactured by Shin-Etsu Chemical Co., Ltd.). However, in Example 4, the low molecular weight cyclic siloxane was investigated. Decamethylcyclopentasiloxane (D5) functions as a solvent that evaporates at room temperature, but its boiling point is high at 210°C, so a small amount may remain in the PDMS and form a silicone gel. Therefore, we investigated various low-molecular-weight silicones using the following cyclic silicones (D4-6) and linear silicones (L4-6).

[0059] [ka]

[0060] In air, an oligomer of UV-curable PDMS, a crosslinking agent, and six types of low-molecular-weight silicones were mixed in the proportions listed in Table 3 using a rotation-orbit mixer (2000 rpm, 4 minutes). The mixture was then spin-coated onto a silicon-silicon wafer in a glove box at 6000 rpm for 30 seconds, and the film was cured by UV irradiation for 1 minute. Subsequently, it was irradiated with VUV for 3 minutes. The film thickness of the obtained films was measured by spectroscopic ellipsometry (Table 3). Although the film thicknesses differed due to the different boiling points and viscosities of each low-molecular-weight silicone, the refractive indices were almost the same, ranging from 1.42 to 1.45. Table 3 shows the film thickness of the PDMS layer when various low-molecular-weight silicones are used.

[0061] [Table 3]

[0062] To confirm the barrier performance of these alternating stacked structures of PDMS and PHPS layers, a barrier layer structure was fabricated on top of an organic EL element, and the barrier performance was confirmed from the emission image of the organic EL element. Organic EL elements are particularly susceptible to oxidation from water vapor at the organic layer / electrode interface. When interfacial oxidation occurs, charge injection and transport do not occur, leading to an increase in the non-emitting area. By observing this increase in the non-emitting area (shrinkage), it is possible to confirm the barrier performance.

[0063] As an organic EL element, the organic EL element shown in Figure 10 was fabricated on a transparent electrode ITO patterned on a 3cm x 3cm glass substrate. The organic EL element was fabricated by depositing the following organic materials using vacuum deposition. The light-emitting area of ​​the organic EL element is 2mm x 2mm. The barrier structure made of alternating PDMS / PHPS layers is called TFE (Thin Film Encapsulation). The alternating PDMS / PHPS TFE structure was fabricated on the fabricated organic EL by spin coating. Fabrication was performed under nitrogen. The thickness of the PHPS layer was 150nm (VUV irradiation 6,000mJ / cm²). 2 The PDMS layer thickness is as shown in Table 3. Each PDMS / PHPS layer unit is considered one unit, and a total of 3 units (6 layers in total) were formed.

[0064] [ka]

[0065] The obtained organic EL elements were stored in a constant temperature and humidity chamber (60°C / 90%RH), and the emission image of the organic EL was observed using an optical microscope. Figure 9 shows the results. Here, bare OLEDs are those without a TFE structure. Immediately after fabrication (0 hours), all elements showed uniform emission, but the bare OLED elements without a TFE structure did not emit light even after 67 hours. This is thought to be the result of interfacial oxidation by water vapor occurring across the entire element. Storage performance differed depending on the silicone, but high performance was obtained not only with D5, but also with L5, L6, and D6. With D5, emission ceased after 504 hours. Among these, D6 and L5 showed particularly high storage performance. In other words, even if the PHPS barrier layer is the same, it was shown that the barrier performance differs depending on the PDMS layer which functions as a stress relaxation layer. We consider this to be related to the coating characteristics. If we only consider the thickness of the PDMS layer, D6 and L6 are superior as shown in Table 3, but ultimately this alone cannot explain the results. Although there are irregularities and foreign matter on the organic EL element, we believe that the PDMS layer using D6 and L5 effectively covers these irregularities and foreign matter.

[0066] In this invention, it was demonstrated that a barrier layer structure created by a wet process is effective for organic EL elements, which are known to be susceptible to water vapor. Furthermore, it was shown that the type of low-molecular-weight silicone used as the dilution solution for the PDMS layer, which acts as a stress relaxation layer, also has an influence on the coating properties. In particular, high storage stability (over 1,300 hours at 60°C / 90%RH) was achieved with D6 and L5.

Claims

1. Step 1 involves applying or printing a solution containing a polysilazane compound with a Si-N main skeleton onto an object, Step 2 involves irradiating a polysilazane compound on an object with vacuum ultraviolet light having a wavelength of 100-190 nm under a nitrogen atmosphere to form a silicon nitride-based layer. It has, The integrated amount of the vacuum ultraviolet light irradiated is 6,000 to 24,000 mJ / cm². A method for manufacturing a barrier layer structure, characterized in that the thickness of the barrier layer structure is 112 to 250 nm.

2. The method for producing a barrier layer structure according to claim 1, characterized in that the polysilazane compound is perhydropolysilazane (PHPS).

3. A method for manufacturing a barrier layer structure according to claim 1, characterized in that the barrier layer is irradiated with vacuum ultraviolet light having a wavelength of 100 to 190 nm, and then further irradiated with ultraviolet light having a wavelength of 200 to 230 nm.

4. The method for manufacturing a barrier layer structure according to claim 1, further comprising step 3, in addition to steps 1 and 2, step 3, of applying or printing a solution containing at least one selected from ultraviolet-curable polysiloxane, acrylic resin, and epoxy resin onto a silicon nitride-based film on an object, and curing it with light or heat to form a resin layer.

5. The method for manufacturing a barrier layer structure according to claim 4, characterized in that steps 1 to 3 are performed multiple times in this order to alternately laminate the silicon nitride-based layer and the resin layer.

6. The method for manufacturing a barrier layer structure according to claim 1, characterized in that in step 2, ultraviolet light with a wavelength of 100 to 190 nm is irradiated at a temperature of 15 to 40°C.

7. The method for manufacturing a barrier layer structure according to claim 1, characterized in that, prior to step 1, the object is surface-modified by vacuum ultraviolet light or UV ozone cleaning.

8. A barrier structure of a silicon nitride-based layer formed on an object by the method for manufacturing a barrier layer structure described in Claim 1, A barrier layer structure characterized by having a silicon nitride-based layer structure with a thickness of 112 to 250 nm and a water vapor transmission rate of 2.6 × 10⁻³ g / m² / day or less.

9. The barrier layer structure according to claim 8, characterized in that there are no cracks when the silicon nitride-based layer is observed with a scanning electron microscope.

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