Substrate for flexible display and method of manufacturing the substrate

Abstract

A substrate for a flexible display is disclosed. The substrate has a film stress range that does not affect an electronic device such as a thin film transistor, and includes a barrier layer having excellent oxygen and moisture blocking characteristics, and a method of manufacturing the substrate. The substrate includes: a plastic substrate having a glass transition temperature from about 350° C. to about 500° C.; and a barrier layer disposed on the plastic substrate, having a multi-layer structure, wherein at least one silicon oxide layer and at least one silicon nitride layer are alternately stacked on each other, and having a film stress from about −200 MPa to about 200 MPa due to the at least one silicon oxide layer and the at least one silicon nitride layer.

1 . A flexible substrate, comprising:
 a plastic substrate having a glass transition temperature from about 350° C. to about 500° C.; and   a barrier layer disposed on the plastic substrate, having a multi-layer structure, which comprises at least one silicon oxide layer and at least one silicon nitride layer that are alternately stacked on each other, the barrier layer having a film stress from about −200 MPa to about 200 MPa.   
     
     
         2 . The substrate of  claim 1 , wherein the barrier layer comprises:
 a first silicon oxide layer;   a silicon nitride layer stacked on the first silicon oxide layer; and   a second silicon oxide layer stacked on the silicon nitride layer.   
     
     
         3 . The substrate of  claim 1 , wherein the barrier layer comprises:
 a first silicon oxide layer;   a first silicon nitride layer stacked on the first silicon oxide layer;   a second silicon oxide layer stacked on the first silicon nitride layer;   a second silicon nitride layer stacked on the second silicon oxide layer; and   a third silicon oxide layer stacked on the second silicon nitride layer.   
     
     
         4 . The substrate of  claim 1 , wherein the barrier layer comprises:
 a first silicon oxide layer;   a first silicon nitride layer stacked on the first silicon oxide layer;   a second silicon oxide layer stacked on the first silicon nitride layer;   a second silicon nitride layer stacked on the second silicon oxide layer;   a third silicon oxide layer stacked on the second silicon nitride layer;   a third silicon nitride layer stacked on the third silicon oxide layer; and   a fourth silicon oxide layer stacked on the third silicon nitride layer.   
     
     
         5 . The substrate of  claim 1 , wherein the at least one silicon oxide layer has compressive film stress, and wherein the at least one silicon nitride layer has tensile film stress. 
     
     
         6 . The substrate of  claim 1 , wherein a film density of the at least one silicon nitride layer is from about 2.5 g/cm 3  to about 2.7 g/cm 3 . 
     
     
         7 . The substrate of  claim 1 , wherein a hydrogen atom content in the at least one silicon nitride layer is from about 13% to about 17%. 
     
     
         8 . The substrate of  claim 1 , wherein a thickness of each of the at least one silicon nitride layer is from about 200 Å to about 1000 Å. 
     
     
         9 . The substrate of  claim 1 , wherein a thickness of each of the at least one silicon oxide layer is from about 1000 Å to about 3000 Å. 
     
     
         10 . The substrate of  claim 1 , wherein the plastic substrate comprises polyimide. 
     
     
         11 . A method of manufacturing a flexible substrate, the method comprising:
 providing a plastic substrate having a glass transition temperature from about 350° C. to about 500° C.; and   forming a barrier layer having a film stress from about −200 MPa to about 200 MPa by alternately stacking at least one silicon oxide layer and at least one silicon nitride layer on the plastic substrate.   
     
     
         12 . The method of  claim 11 , wherein the forming of the barrier layer comprises forming the barrier layer using a high temperature deposition technique at a temperature from about 350° C. to about 400° C. 
     
     
         13 . The method of  claim 11 , wherein the barrier layer comprises:
 a first silicon oxide layer;   a silicon nitride layer stacked on the first silicon oxide layer; and   a second silicon oxide layer stacked on the silicon nitride layer.   
     
     
         14 . The method of  claim 11 , wherein the barrier layer comprises:
 a first silicon oxide layer;   a first silicon nitride layer stacked on the first silicon oxide layer;   a second silicon oxide layer stacked on the first silicon nitride layer;   a second silicon nitride layer stacked on the second silicon oxide layer; and   a third silicon oxide layer stacked on the second silicon nitride layer.   
     
     
         15 . The method of  claim 11 , wherein the barrier layer comprises:
 a first silicon oxide layer;   a first silicon nitride layer stacked on the first silicon oxide layer;   a second silicon oxide layer stacked on the first silicon nitride layer;   a second silicon nitride layer stacked on the second silicon oxide layer;   a third silicon oxide layer stacked on the second silicon nitride layer;   a third silicon nitride layer stacked on the third silicon oxide layer; and   a fourth silicon oxide layer stacked on the third silicon nitride layer.   
     
     
         16 . The method of  claim 11 , wherein the at least one silicon oxide layer has compressive film stress, and wherein the at least one silicon nitride layer has tensile film stress. 
     
     
         17 . The method of  claim 11 , wherein a film density of the at least one silicon nitride layer is from about 2.5 g/cm 3  to about 2.7 g/cm 3 . 
     
     
         18 . The method of  claim 11 , wherein a hydrogen atom content in the at least one silicon nitride layer is from about 13% to about 17%.