Thin film structures and devices with integrated light and heat blocking layers for laser patterning
View Patent ↗Selective removal of specified layers of thin film structures and devices, such as solar cells, electrochromics, and thin film batteries, by laser direct patterning is achieved by including heat and light blocking layers in the device/structure stack immediately adjacent to the specified layers which are to be removed by laser ablation. The light blocking layer is a layer of metal that absorbs or reflects a portion of the laser energy penetrating through the dielectric/semiconductor layers and the heat blocking layer is a conductive layer with thermal diffusivity low enough to reduce heat flow into underlying metal layer(s), such that the temperature of the underlying metal layer(s) does not reach the melting temperature, T m , or in some embodiments does not reach (T m )/3, of the underlying metal layer(s) during laser direct patterning.
1. An apparatus for forming electrochemical devices, comprising:
a first system for blanket depositing on a substrate a stack including a cathode current collector layer, a heat blocking layer, a light blocking layer, a cathode layer, an electrolyte layer, an anode layer, an anode current collector layer and a protective coating layer; and
a second system for direct laser patterning said stack, said second system comprising at least one laser;
wherein said light blocking layer is a layer of metal characterized by the property of absorbing or reflecting a portion of the laser energy reaching said light blocking layer and said heat blocking layer is a conductive layer with thermal diffusivity, D, low enough to reduce heat flow through said heat blocking layer during laser direct patterning such that the temperature of an adjacent device layer exceeds the melting temperature, T m , of said adjacent device layer.
2. The apparatus of claim 1 , wherein said first system is a cluster tool.
3. The apparatus of claim 1 , wherein said first system is an in-line tool.
4. The apparatus of claim 1 , wherein said first system comprises at least one stand-alone tool.
5. The apparatus of claim 1 , wherein said second system is a stand-alone tool.
6. The apparatus of claim 1 , wherein said second system is integrated into said first system.
7. The apparatus of claim 1 , wherein said electrochemical devices are thin film batteries.
8. The apparatus of claim 1 , wherein said second system comprises multiple lasers.
9. The apparatus of claim 1 , wherein said second system comprises lasers positioned above said stack and lasers positioned below said stack and wherein said stack is held on a stage, said stage having apertures below said stack for accommodation of direct laser patterning of said stack by said lasers positioned below said stack.
10. The apparatus of claim 1 , wherein said second system comprises an ultraviolet-visible laser.
11. The apparatus of claim 10 , wherein said ultraviolet-visible laser is a picosecond laser.
12. The apparatus of claim 1 , wherein said second system comprises an infrared laser.
13. The apparatus of claim 12 , wherein said infrared laser is a picosecond laser.
14. The apparatus of claim 1 , wherein said second system comprises a visible laser.
15. The apparatus of claim 14 , wherein said visible laser is a picosecond laser.
16. The apparatus of claim 1 , wherein the thickness of said heat blocking layer is greater than the thermal diffusion length, √(Dτ), wherein τ is the laser pulse duration of said at least one laser.
17. The device of claim 1 , wherein the thermal diffusivity of said heat blocking layer is less than 0.1 cm 2 /s.
18. The apparatus of claim 1 , wherein said at least one laser is a nanosecond laser.
19. The apparatus of claim 1 , wherein said second system, said stack and said substrate are configured for at least one laser beam to pass through said substrate before reaching said heat blocking layer.
20. The apparatus of claim 1 , wherein said light blocking layer and said heat blocking layer are the same layer.