1. Field of the Invention
Embodiments disclosed herein generally relate to the deposition of thin films using chemical vapor deposition (CVD) processing. More particularly, embodiments generally relate to methods for depositing barrier layers onto large area substrates.
2. Description of the Related Art
Organic light emitting diodes (OLED) are used in the manufacture of television screens, computer monitors, mobile phones, other hand-held devices, or other devices for displaying information. A typical OLED may include layers of organic material situated between two electrodes that are all deposited on a substrate in a manner to form a matrix display panel having individually energizable pixels. The OLED is generally placed between two glass panels, and the edges of the glass panels are sealed to encapsulate the OLED therein.
The encapsulation is achieved by sealing the active materials in inert atmosphere using a glass lid secured by a bead of UV-cured epoxy resin. The rigid encapsulation is not applicable to flexible displays, where a durable and flexible encapsulation is necessary to protect the active OLED materials from water moisture and oxygen. One approach is to use a multilayer encapsulating structure as a barrier to water moisture and oxygen permeation. Inorganic layers can be incorporated into the multilayer encapsulating structure as the main barrier layer. Organic layers can also be incorporated for the purposes of stress relaxation and water/oxygen diffusion channels decoupling layer.
Silicon nitride (SiN) is known as a good barrier material, thus it shows potential as an inorganic barrier layer in the multilayer encapsulation structure. However, SiN films deposited at low temperatures such as below 100 degrees Celsius have high stress, which can induce film peeling, also known as delamination, or mismatch issues in multi-film stack configurations. Due to the sensitivity of some of the layers of the OLED device, subsequently deposited layers over OLED materials will need to be deposited at lower temperatures, such as at temperatures less than 100° C.
Thus, there is a need for methods of depositing encapsulation/barrier films onto large area substrates with improved water-barrier performance to protect the devices underneath.