Flexible display device having enhanced thin film semiconductive layer and method of manufacture
View Patent ↗A manufacturing method for a flat panel display device includes forming a barrier layer on a flexible plastic substrate by RF sputtering, forming an amorphous silicon layer on the plastic substrate, and subjecting the amorphous silicon layer to a rapid heat treatment so as to thereby improve electrical characteristics and/or homogeneity of the amorphous silicon layer.
1. A manufacturing method comprising:
depositing an amorphous silicon layer over a plastic substrate by way of a chemical vapor deposition (CVD) process, where the CVD process tends to leave behind substantial amounts of hydrogen and/or other undesired elements that impede homogeneous formation of stoichiometric amorphous silicon; and
subjecting at least regions of the amorphous silicon layer to a rapid heat treatment that enhances removal of substantial portions of the left-behind hydrogen and/or other undesired elements while not substantially affecting the plastic substrate adversely,
wherein the rapid heat treatment includes ramping up temperature at a rate of about 0.5° C./second to about 20° C./second and ramping down temperature at a rate of about 0.5° C./minute to about 10° C./minute.
2. The method of claim 1 , further comprising:
forming a barrier layer on the plastic substrate before depositing the amorphous silicon layer, where the barrier layer is substantially impermeable to a predefined one or more gases or vapors.
3. The method of claim 2 , wherein the barrier layer includes a silicon oxynitride (Si x O y N z ) and x, y and z are predetermined numbers.
4. The method of claim 3 , wherein the barrier layer has a concentration ratio of oxygen to other non-silicon elements of about 0.35 to about 0.85.
5. The method of claim 3 , further comprising:
forming a buffer layer between the plastic substrate and the barrier layer.
6. The method of claim 5 , wherein said buffer layer is structured to cure defects in the barrier layer.
7. The method of claim 3 , wherein the plastic substrate has a thickness of about 100 μm to about 300 μm.
8. The method of claim 3 , wherein the barrier layer has a thickness of about 10 nm to about 30 nm.
9. The method of claim 3 , wherein the barrier layer is formed by radio frequency (RF) sputtering using a target containing Si 3 N 4 .
10. The method of claim 9 , wherein the radio frequency (RF) sputtering is performed under radio frequency of about 10 MHz to about 15 MHz.
11. The method of claim 9 , wherein radio frequency (RF) sputtering is performed using oxygen (O 2 ) and argon (Ar) as reaction gases.
12. The method of claim 9 , wherein the radio frequency (RF) sputtering is performed at a temperature of about 100° C. or below.
13. The method of claim 1 , wherein the chemical vapor deposition is performed at no more than about 180° C.
14. The method of claim 1 , wherein the rapid heat treatment includes heating a maximum temperature of about 300° C. for about 1 minute to about 5 minutes using an oven.
15. The method of claim 1 , wherein the ramping up rate is about 1.5° C./second to about 3° C./second.
16. A manufacturing method comprising:
depositing an amorphous silicon layer over a plastic substrate by way of a chemical vapor deposition (CVD) process, where the CVD process tends to leave behind substantial amounts of hydrogen and/or other undesired elements that impede homogeneous formation of stoichiometric amorphous silicon; and
subjecting at least regions of the amorphous silicon layer to a rapid heat treatment that enhances removal of substantial portions of left-behind hydrogen and/or other undesired elements while not substantially affecting the plastic substrate adversely,
wherein the rapid heat treatment includes subjecting the amorphous silicon layer to heat generated by a laser beam having a wavelength of about 280 nm to about 320 nm and an energy density of about 190 mJ/cm 2 to about 240 mJ/cm 2 ; and
wherein the rapid heat treatment causes the amorphous silicon layer to undergo a ramping up of its temperature at a rate of about 0.5° C./second to about 20° C./second and ramping down of its temperature at a rate of about 0.5° C./minute to about 10° C./minute.
17. A manufacturing method comprising:
fixing a plastic substrate on a dummy glass substrate;
forming a barrier layer on the plastic substrate by RF sputtering;
depositing an amorphous silicon layer on the barrier layer by chemical vapor deposition; and
subjecting the amorphous silicon layer to a rapid heat treatment,
wherein the chemical vapor deposition is performed at about 90° C. to about 180° C., and the rapid heat treatment is performed at about 150° C. to about 800° C., and
wherein the rapid heat treatment includes ramping up temperature at a rate of about 0.5° C./second to about 20° C./second and ramping down temperature at a rate of about 0.5° C./minute to about 10° C./minute.
18. The method of claim 17 , wherein the chemical vapor deposition is performed at about 90° C. to about 130° C., and the rapid heat treatment is performed at about 200° C. to about 500° C.
19. The method of claim 18 , wherein the barrier layer includes a silicon oxynitride (SiON) and the barrier layer has a concentration ratio of elements O/(N+O) of about 0.35 to about 0.85.
20. The method of claim 17 , wherein said chemical vapor deposition process is one that tends to leave behind substantial amounts of hydrogen or other undesired elements still bound to silicon atoms of the amorphous silicon layer.
21. The method of claim 17 , wherein said rapid heat treatment is one that enhances removal of substantial portions of the left-behind hydrogen and/or other undesired elements while not substantially affecting the plastic substrate adversely.