Pattern transfer printing of multi-layered features
Pattern transfer sheets and methods are provided, providing multi-layer paste stack lines that are printed on a receiving substrate in a single illumination step. The paste is filled layer-by-layer, possibly having different materials in different layers, with layer thickness controlled by parameters of the filling elements, e.g., in case of blades, the pressure, angle, velocity and flexibility (material) of the blade. Specifically, a bottom layer of the stack may be configured to interface the receiving substrate while one or more top layers may be configured to optimize the quality of the printed features. For example, bottom layers may comprise to bind to the substrate, to modify the substrate (e.g., forming selective emitter (SE) therein) and/or provide a barrier from top layer(s) which may not be compatible with the substrate (e.g., copper on silicon). Releasing material may be used to support the single step release of the stack line.
1. A pattern transfer method comprising:
filling, layer-by-layer, a plurality of stack lines that are each made of a plurality of printing paste layers into a plurality of trenches on a source substrate, wherein the stack lines are filled into corresponding trenches that are arranged in a pattern, and
releasing-the plurality of stack lines from the corresponding plurality of trenches onto a receiving substrate simultaneously, in a single illumination step by a laser beam, forming transferred stack lines on the receiving substrate,
wherein at least two of the paste layers comprise different material compositions.
2. The pattern transfer method of claim 1 , wherein the filling is carried out by a plurality of blades, one respective blade for each paste layer, and the pattern transfer method further comprising adjusting a thickness of at least one of the paste layers by adjusting at least one of: a pressure applied to the respective blade, a blade angle of the respective blade, a blade velocity of the respective blade, and/or a flexibility of the respective blade.
3. The pattern transfer method of claim 2 , wherein the pressure is selected within 2-4 bar, the blade angle is selected within 30°-120°, the blade velocity is selected within 25-100 mm/sec and/or a blade material is selected from stainless steel, plastic and rubber.
4. The pattern transfer method of claim 1 , wherein the at least two of the paste layers that comprise the different material compositions yield a configuration on the receiving substrate that is selected from one of:
a bottom paste layer comprising a material configured to bind the transferred stack lines to the receiving substrate and at least one top paste layer comprising a material configured to provide conductivity along the transferred stack lines,
a bottom paste layer comprising a material configured to form selective emitter (SE) lines on the receiving substrate, and at least one top paste layer configured to provide conductivity along the transferred stack lines and electrical contact to the receiving substrate, and
a bottom paste layer comprising a material configured to provide a barrier and/or seed layer upon the receiving substrate and at least one top layer comprising a material configured to provide conductivity along the transferred stack lines.
5. The pattern transfer method of claim 4 , wherein the bottom paste layer comprises a releasing material composition.
6. The pattern transfer method of claim 1 , further comprising:
prior to filling the plurality of stack lines, coating the trenches internally with a coating configured to disintegrate upon illumination by the laser beam, to enhance the releasing of the stack lines, and
optionally after the releasing, cleaning the receiving substrate by removing disintegration products of the coating therefrom.
7. The pattern transfer method of claim 6 , wherein the coating is carried out by at least one of:
spreading a coating solution having a solid content between 10% and 20% and drying thereof, and
at least one application technique of: gravure, micro gravure, transfer roll, slot extrusion, reverse comma, Mayer rod and/or doctor blade.
8. The pattern transfer method of claim 6 , further comprising the cleaning of the receiving substrate, carried out by at least one of: high temperature decomposition, illumination by the illumination source used to release the stack lines, selective laser vaporization, vacuum assisted vaporization, air blowing and/or solvent washing.