Patent Publication Number: US-2019198807-A1

Title: Barrier film and barrier structure including the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of U.S. provisional application Ser. No. 62/610,266, filed on Dec. 25, 2017. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification. 
    
    
     TECHNICAL FIELD 
     The disclosure relates to a barrier film and a barrier structure including the same. 
     BACKGROUND 
     Organic light-emitting devices (OLEDs) have been used in various mobile devices because of their advantages over conventional light sources such as large illumination area, low power consumption, lightweight, slimness and flexibility, etc. Nevertheless, OLEDs are liable to be deteriorated due to invasion of moisture and oxygen, which may reduce their operational performance and lifetime. Various barrier films with low WVTR/OTR and improved optical characteristics are proposed to overcome those issues. 
     SUMMARY 
     An embodiment of the disclosure provides a barrier film including an organo-silicon polymeric composition having Si 4 —N 4  bonds and Si—OH bonds. A peak height of Si 4 —N 4  bonds in an infrared absorption spectrum is represented by A, and the peak height of Si—OH bonds in the infrared absorption spectrum is represented by B; and a ratio of A to B is greater than 2. 
     An embodiment of the disclosure provides a barrier structure including a substrate; and a first barrier film disposed over the substrate, the first barrier film comprising a first organo-silicon polymeric composition having Si 3 —N 4  bonds and Si—OH bonds, wherein a peak height of Si 4 —N 4  bonds in an infrared absorption spectrum is represented by A1, a peak height of Si—OH bonds in the infrared absorption spectrum is represented by B1, and a ratio of A1 to B1 is greater than 2. 
     An embodiment of the disclosure provides a method for forming a barrier film. The method comprises forming an organo-silicon polymeric composition having Si 4 —N 4  bonds and Si—OH bonds over a substrate, wherein a peak height of Si 4 —N 4  bonds in an infrared absorption spectrum is represented by A, and a peak height of Si—OH bonds in the infrared absorption spectrum is represented by B; and a ratio of A to B is greater than 2. 
     In order to make the aforementioned and other features and advantages of the disclosure comprehensible, several exemplary embodiments accompanied with figures are described in detail below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure. 
         FIG. 1  to  FIG. 7  are schematic diagrams illustrating a method for manufacturing an OLED according to an embodiment of the disclosure. 
         FIG. 8A  to  FIG. 8B  are cross-sectional views of barrier structures according to some embodiments of the disclosure. 
         FIG. 9A  to  FIG. 9C  are schematic diagrams illustrating a method for manufacturing the barrier structure according to an embodiment of the disclosure. 
         FIG. 10A  to  FIG. 10E  are cross-sectional views of different interior arrangements of barrier films in the barrier structure according to some embodiments of the disclosure. 
         FIG. 11  is a schematic diagram of the reaction mechanisms for the film deposition according to some embodiments of the disclosure. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Reference will now be made in detail to the present preferred embodiments of the disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts. 
       FIG. 1  to  FIG. 7  are cross-sectional views illustrating a method for manufacturing an OLED according to an embodiment of the disclosure. The method for manufacturing an OLED will be described in more detail hereinafter. 
     Referring to  FIG. 1 , a sealing adhesive  110  is provided. The sealing adhesive  110  may be any commercially available sealing tapes which provide acceptable sealing capability and adhesion capability. The sealing adhesive  110  may be provided with a release film  115  covering thereon. In some embodiments, the release film  115  is disposed on one surface of the sealing adhesive  110 . For example, the thickness of the sealing adhesive  110  ranges from about 30 μm to about 70 μm. As shown in  FIG. 1 , an optical reflective film  120  is provided. In some embodiments, the optical reflective film  120  includes a metal foil, such as aluminium foil, copper foil or the like. For example, the thickness of the optical reflective film  120  ranges from about 20 μm to about 40 μm. 
     Referring to  FIG. 2 , a lamination process is performed to adhere the optical reflective film  120  with the other surface of the sealing adhesive  110  such that the optical reflective film  120  and release film  115  are adhered with opposite surfaces of the sealing adhesive  110  respectively. Here, the optical reflective film  120  may be any optical film capable reflecting and protecting an OLED illustrated in  FIG. 7 . Thus, a sealing member  100  including the sealing adhesive  110 , the release film  115  and the optical reflective film  120  is accomplished. 
     Next, referring to  FIG. 3  and  FIG. 4 , a barrier member  250  including a barrier film  130  and a carrier  135  is provided. The barrier member  250  plays a role as a supporting base for the subsequent OLED fabrication. The description regarding the fabrication of the barrier member  250  will be discussed later and is omitted here. Then, an OLED including an anode layer  140 , an organic light-emitting layer  150  and a cathode layer  160  is formed over a surface of the barrier member  250 . For example, the OLED is an active matrix OLED or a passive matrix OLED. The active matrix or passive matrix OLED may serve as a display with display pixels or a light source without pixel design. In some embodiments, the anode layer  140 , the organic light-emitting layer  150  and the cathode layer  160  may be formed by vacuum evaporation processes in the stated order over the barrier member  250 , namely over the barrier film  130 . For example, the anode layer  140  is a transparent conductive oxide layer (e.g., indium tin oxide layer, indium zinc oxide layer or the like) and the cathode layer  160  is a metal layer. The organic light-emitting layer  150  may include at least one organic layer capable of emitting light with predetermined wavelength. Furthermore, the OLED may further include at least one of the functional layers to enhance the performance thereof. For example, the OLED may further include an electron injection layer (EIL) and/or an electron transport layer (ETL) disposed between the organic light-emitting layer  150  and the anode layer  140 . Furthermore, the OLED may further include a hole injection layer (HIL) and/or a hole transport layer (HTL) disposed between the organic light-emitting layer  150  and the cathode layer  160 . 
     Referring to  FIG. 2  and  FIG. 5 , the release film  115  is removed from the sealing adhesive  110  prior to an encapsulation process for the OLED. The encapsulation process for the OLED is then performed by laminating the sealing adhesive  110  having the optical reflective film  120  formed thereon onto the barrier member  250  to entirely encapsulate the OLED including the anode layer  140 , the organic light-emitting layer  150 , and the cathode layer  160 . Here, the sealing member  100  including the sealing adhesive  110  and the optical reflective film  120  is pressed onto the OLED and the barrier member  250  such that the sealing adhesive  110  deforms to some extents so as to better fit the topography the OLED including the anode layer  140 , the organic light-emitting layer  150 , and the cathode layer  160 . After lamination of the barrier member  250 , other processes such as curing and edge encapsulation processes to further enhance the resistance against outer environmental issues may be conducted. 
     Referring to  FIG. 6 , the carrier  135  is detached from the barrier film  130 . An out-coupling film (OC film)  170  may be attached onto the bottom surface which was originally covered by carrier  135  to improve optical properties of the finished OLED. Hence, an OLED package with low WVTR/OTR is provided. 
     OLEDs are liable to be deteriorated due to invasion of moisture and oxygen, which may substantially reduce their operational performance and lifetime. Various barrier films with low WVTR/OTR and improved optical characteristics are proposed in this disclosure. Further, there are also demands for barrier films which may reduce surface roughness caused by processing defects (e.g., pinholes and particles). 
     In an embodiment of the disclosure, a barrier structure  300  with low WVTR/OTR and improved optical characteristics such as high light-transmittance, high refractive index etc. is shown in  FIG. 8A . Referring to  FIG. 8A , the barrier structure  300  includes a substrate  310  and a barrier film  330  disposed over the substrate  310 . The barrier film  330  includes an organo-silicon polymeric composition having Si 3 —N 4  bonds and Si—OH bonds. The method for manufacturing the barrier structure  300  as shown in  FIG. 9A  to  FIG. 9C  will be described in more detail hereinafter. 
     Referring to  FIG. 9A , the substrate  310  is provided. The material of the substrate  310  may be any materials having Tg less than 150° C., for example, plastics such as polyethylene naphthalate, polyethylene terephthalate, cylco-olefin polymer or the like. In some embodiments, the substrate  130  is a flexible substrate. In some alternative embodiments, the substrate  130  is a rigid substrate. Next, a cleaning process may be then performed on the substrate  310 . 
     Referring to  FIG. 9B , a wet coating process is performed on the substrate  310  to form a planarization layer  320  over the substrate  310 . The wet coating process may be selected from spray coating, spin coating, ink-jet printing or the like. The materials for forming the planarization layer  320  may include metal oxide, silicon oxide-based material containing metal oxide particles, poly(methyl methacrylate) (PMMA) containing metal oxide particles or the like. In an embodiment of the disclosure, the metal oxide particles in the planarization layer  320  may be ZrO 2 , TiO 2  or the like. In an embodiment of the disclosure, the particle scale of the metal oxide ranges from 0.3 μm to 1 μm. Through the wet coating process, the planarization layer  320  may cover or fill the surface defects (e.g., pinholes and particles) on the surface of the substrate  310  such that the roughness of the surface of the substrate  310  is reduced. In an embodiment of the disclosure, the thickness of the planarization layer may range between 1 μm and 2 μm. In another embodiment of the disclosure, the planarization layer  320  may exhibit a WVTR (water vapor transmission rate) about 0.1 g/m 2  day ˜10 g/m 2  day. In still another embodiment of the disclosure, the roughness of the planarization layer  320  is measured to be Ra&lt;1 nm and Rz&lt;15 nm. 
     Next, referring to  FIG. 9C , a barrier film  330  is formed on the planarization layer  320  by a CVD process, for example. In an embodiment of the disclosure, the barrier film  330  is formed by a ICP-PECVD process which may be conducted under low process temperature. In an embodiment of the disclosure, the barrier film  330  may include an organo-silicon polymeric composition having Si 3 —N 4  bonds and Si—OH bonds. In the embodiment of the disclosure, a peak height of Si 4 —N 4  bonds in an infrared absorption spectrum is represented by A, a peak height of Si—OH bonds in the infrared absorption spectrum is represented by B, and a ratio of A to B is greater than 2. In some embodiments, the ratio of B to A ranges between 0.4 and 0.5. It is believed that Si—OH bonds tend to cause swelling and plumping of the films, therefore the smoothness and flatness of the films could be deteriorated. Moreover, pinholes may arise in such films during the following elevated-temperature processes due to compression stress. Within the range (i.e. the ratio of A to B is greater than 2), less pinholes will occur during subsequent elevated-temperature processes of the barrier film according to the present disclosure. 
     In an embodiment of the disclosure, a first barrier film  330   a  may be disposed over one side of the substrate  310 ′, and a second barrier film  330   b  may be disposed over the other side of the substrate  310 ′ as shown in the barrier structure  300 ′ of  FIG. 8B . The first barrier film  330   a  may include a first organo-silicon polymeric composition having Si 4 —N 4  bonds and Si—OH bonds, wherein a peak height of Si 4 —N 4  bonds in an infrared absorption spectrum is represented by A1, a peak height of Si—OH bonds in the infrared absorption spectrum is represented by B1, and a ratio of A1 to B1 is greater than 2. Further, the second barrier film  330   b  may include a second organo-silicon polymeric composition having Si 4 —N 4  bonds and Si—OH bonds, wherein a peak height of Si 4 —N 4  bonds in the infrared absorption spectrum is represented by A2, a peak height of Si—OH bonds in the infrared absorption spectrum is represented by B2, and a ratio of A2 to B2 is greater than 2. Within these ranges (i.e. the ratio of A1/B1 or A2/B2 is greater than 2), less pinholes will occur during subsequent elevated-temperature processes of the barrier films according to the present disclosure. In another embodiment of the disclosure, the first organo-silicon polymeric composition is the same as the second organo-silicon polymeric composition. In still another embodiment of the disclosure, the first organo-silicon polymeric composition is different from the second organo-silicon polymeric composition. 
     Referring to  FIG. 9C  again, the barrier structure  300  is thus provided. In an embodiment of the disclosure, the barrier structure  300  may have a planarization layer  320  sandwiched between a substrate  310  and a barrier film  330 . In another embodiment of the disclosure, a planarization layer  320  may be optionally omitted. 
     The barrier film according to the disclosure and the fabrication thereof will be elucidated in more detail hereinafter by way of Examples. 
     The barrier film according to the present disclosure is thus provided. In an embodiment of the disclosure, there is provided a barrier film which includes an organo-silicon polymeric composition having Si 3 —N 4  bonds and Si—OH bonds. The peak height of Si 4 —N 4  bonds in an infrared absorption spectrum is represented by A, the peak height of Si—OH bonds in the infrared absorption spectrum is represented by B, and a ratio of A to B is greater than 2. In another embodiment of the disclosure, the ratio of B1 to A1 ranges between 0.4 and 0.5. Within the range, less pinholes will occur during subsequent elevated-temperature processes of the barrier film according to the present disclosure. In still another embodiment of the disclosure, the barrier film exhibits a WVTR (water vapor transmission rate) smaller than 5×10 −5  g/m 2  day. In a further embodiment of the disclosure, a thickness of the barrier film ranges between about 50 μm and about 110 μm. Thus, barrier films according to the present disclosure with low WVTR/OTR and improved operational properties are obtained. 
     Besides having low WVTR/OTR to prevent deterioration of the devices, the barrier films used in OLEDs are expected to optimize the optical characteristics of the devices such as light-transmittance, refractive index and the like. Hence, barrier films according to the disclosure meeting at least these requirements are proposed. 
     Referring to  FIG. 10A  to  FIG. 10E , barrier structures  10 ,  20 ,  30 ,  40 , and  50  with barrier films  16 ,  26 ,  36 ,  46 , and  56  having multiple stacked barrier regions  11 ,  12 ,  22 ,  23 ,  31 ,  33 ,  41 ,  42 ,  43 ,  51 ,  52 , and  53  are shown. The substrates  15 ,  25 ,  35 ,  45 , and  55  of the barrier structures  10 ,  20 ,  30 ,  40 , and  50  are similar to the substrate  310  of the barrier structure  300  of  FIG. 8A  and the description thereof will be omitted here. In some embodiments of the disclosure, the ratio of the main elements such as carbon, silicon, and oxygen in the organo-silicon polymeric composition may be adjusted depending on the in-situ recipes for chemical vapour deposition (CVD). A plurality of stacked barrier regions with different element ratios are thus formed on the substrate. It should be noted that the amounts of elements are denoted by weight percentage in the specification. For example, in an embodiment of the present disclosure, the element ratio of the organo-silicon polymeric composition in first barrier regions  11 ,  31 ,  41 , and  51  may be C&gt;Si&gt;O. The element ratio of the organo-silicon polymeric composition in second barrier regions  12 ,  22 ,  42 , and  52  may be C&gt;Si&gt;O. The element ratio of the organo-silicon polymeric composition in third barrier regions  23 ,  33 ,  43 , and  53  may be Si&gt;O&gt;C. It should be noted that the refractive index of each of the plurality of stacked barrier regions varies depending on its composition. In some embodiments of the disclosure, the refractive index of each of the barrier region may be the same or may be different. Further, in the barrier films  16 ,  26 ,  36 ,  46 , and  56 , the plurality of stacked barrier regions are arranged in certain order. Specifically, referring to  FIG. 10A  to  FIG. 10C , the plurality of stacked barrier regions are disposed in the sinusoidal arrangement, and referring to  FIG. 10D  and  FIG. 10E , the plurality of stacked barrier regions are disposed in the monotonic arrangement. That is to say, referring to  FIG. 10A  to  FIG. 10C , in some embodiments of the disclosure, the distribution of the refractive indices of the barrier films  16 ,  26 ,  36  composed of the plurality of stacked barrier regions  11 ,  12 ,  22 ,  23 ,  31 , and  33  may vary periodically. In other embodiments of the disclosure, referring to  FIG. 10D  and  FIG. 10E , the distribution of the refractive indices of the barrier films  46  and  56  composed of the plurality of stacked barrier regions  11 ,  12 ,  22 ,  23 ,  31 , and  33  may not vary periodically. In further embodiments of the disclosure, the thickness of each of the barrier region may be the same or may be different. It should be noted that although the stacked barrier regions illustrated in the figures are distinctly distinguished from each other, the actual boundaries may be indefinite due to the inherent nature of the (CVD) process. 
     Hereinafter, the present disclosure is illustrated through Example 1 and Example 2 regarding fabrication of the barrier films. However, the disclosure is not restricted thereto. 
     Reaction Mechanisms of the Film Deposition 
       FIG. 11  is a schematic diagram of the reaction mechanisms for the film deposition according to some embodiments of the disclosure. The barrier films according to the disclosure are formed by CVD process as describe above. Here are some chemical equations which are believed to take place during the CVD process while using hexamethyldisiloxane (HMDSO) as the main precursor: 
       C 16 H 18 SiO 2 +3N 2 O→2SiO 2 (CH 3 ) 3 +3N 2    [Equation 1]
 
       C 16 H 18 SiO 2 +24N 2 O→2SiO 2 +6CO 2 +9H 2 O+24N 2    [Equation 2]
 
     The dominance of Equation 1 or Equation 2 depends on the respective conditions and recipes while depositing these films. Specifically, if the amounts of O 2  is much more than the amounts of HMDSO in the recipes, it is observed that the reaction of Equation 2 will dominant. Or else the reaction of Equation 1 will take place dominantly during the deposition. Further, referring to  FIG. 11 , the elemental ratios of silicon, oxygen, and carbon of resulting deposited films are about 2:3:5 for Equation 1 and about 1:2:0 for Equation 2. 
     EXAMPLE 1 
     A barrier film in sinusoidal arrangement, such as the arrangement shown in  FIG. 10A , is fabricated using the conditions and recipes shown in Table 1. The barrier film of this example is composed of two stacked barrier regions with different elemental ratios. These stacked barrier regions are deposited sequentially by the inductively coupled plasma—plasma-enhanced CVD (ICP-PECVD) with altering the conditions and recipes in-situ. The barrier film according to the disclosure is thus obtained and the properties thereof are shown in Table 2. Moreover, the elemental ratios are C&gt;Si&gt;O in the barrier region I, and C≥Si&gt;O in the barrier region II, respectively. 
     
       
         
           
               
               
               
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                   
                 HMDSO 
                 N 2 O 
                 Pressure 
                 Power 
                 Time 
               
               
                   
                 Temperature 
                 (sccm) 
                 (sccm) 
                 (mtorr) 
                 (W) 
                 (sec) 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 barrier 
                 &lt;80° C. 
                 100~500 
                 10~100 
                 50~100 
                  500~1000 
                 100~300 
               
               
                 region I 
               
               
                 barrier 
                 &lt;80° C. 
                  20~100 
                 100~1000 
                 20~50  
                 1000~3000 
                 300~500 
               
               
                 region II 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                   
                 Thickness 
                   
               
               
                   
                 Elemental ratio 
                 (nm) 
                 WVTR (g/m2 day) 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                 barrier region I 
                 60%:20%:10% 
                 300~500 
                 0.1~10 
               
               
                 barrier region II 
                 40%:40%:20% 
                 100~300 
                   1~10 −1   
               
               
                   
               
            
           
         
       
     
     EXAMPLE 2 
     A barrier film in monotonic arrangement, such as the arrangement shown in  FIG. 10D  or  FIG. 10E , is fabricated using the conditions and recipes shown in Table 3. The barrier film of this example is composed of three stacked barrier regions with different elemental ratios. These stacked barrier regions are deposited sequentially by the ICP-PECVD with altering the conditions and recipes in-situ. The barrier film according to the disclosure is thus obtained and the properties thereof are shown in Table 4. Moreover, the elemental ratios are C&gt;Si&gt;O in the barrier region I, C≥Si&gt;O in the barrier region II, and Si≥O&gt;C in the barrier region III respectively. 
     
       
         
           
               
               
               
               
               
               
               
             
               
                   
                 TABLE 3 
               
               
                   
                   
               
               
                   
                   
                 HMDSO 
                 N 2 O 
                 Pressure 
                 Power 
                 Time 
               
               
                   
                 Temperature 
                 (sccm) 
                 (sccm) 
                 (mtorr) 
                 (W) 
                 (sec) 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 barrier 
                 &lt;80° C. 
                 100~500 
                 0~50 
                 20~50 
                 500~1000 
                  60~300 
               
               
                 region I′ 
               
               
                 barrier 
                 &lt;80° C. 
                 100~500 
                 10~100 
                  50~100 
                 500~1000 
                 120~300 
               
               
                 region II′ 
               
               
                 barrier 
                 &lt;80° C. 
                  20~100 
                 100~1000 
                 20~50 
                 1000~3000  
                 300~500 
               
               
                 region III′ 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 4 
               
               
                   
                   
               
               
                   
                   
                 Thickness 
                   
               
               
                   
                 Elemental ratio 
                 (nm) 
                 WVTR (g/m 2  day) 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                 barrier region I′ 
                 60%:20%:10% 
                 300~500 
                 0.1~10  
               
               
                 barrier region II′ 
                 40%:40%:20% 
                 100~300 
                     1~10 −1   
               
               
                 barrier region III′ 
                 50%:40%:10% 
                  50~200 
                 10 −1 ~10 −3   
               
               
                   
               
            
           
         
       
     
     The barrier film and the barrier structure comprising the same according to the present disclosure are explained correspondingly hereinbefore. In summary, the barrier film according to the present disclosure has the advantages over conventional barrier films such as low WVTR/OTR and improved optical characteristics such as high light-transmittance, high refractive index and etc. Further, less pinholes will occur during subsequent elevated-temperature processes of the barrier film according to the present disclosure. In addition, by providing a planarization layer in the barrier structure according to the present disclosure, surface defects (e.g., pinholes and particles) may be reduced and the surface roughness may be thus improved. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the disclosure without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the disclosure cover modifications and variations of this disclosure provided they fall within the scope of the following claims and their equivalents.