Laser-seeding for electro-conductive plating
A workpiece ( 100 ) having substrate, such as a glass substrate, can be etched by a laser or by other means to create recessed features ( 200, 202 ). A laser-induced forward transfer (LIFT) process or metal oxide printing process can be employed to impart a seed material ( 402 ), such as a metal, onto the glass substrate, especially into the recessed features ( 200, 202 ). The seeded recessed features can be plated, if desired, by conventional techniques, such as electroless plating, to provide conductive features ( 500 ) with predictable and better electrical properties. The workpieces ( 100 ) can be connected in a stacked such that subsequently stacked workpieces ( 100 ) can be modified in place.
1. A method, comprising:
in a first laser process, directing a beam of laser energy to a workpiece to form a recess within the workpiece, wherein the workpiece comprises a main surface and wherein the recess includes a sidewall surface extending from the main surface;
in a second laser process, forming a seed layer within the recess, wherein forming the seed layer includes directing a beam of laser energy onto a seed material, wherein forming the seed layer comprises:
providing a donor structure comprising a carrier substrate that is transparent to the beam of laser energy and a donor film, wherein the donor film faces toward the workpiece; and
directing the beam of laser energy through the carrier substrate to impinge a portion of the donor film such that at least a portion of the donor film impinged by the laser energy is transferred off from the carrier substrate as a plurality of liquid droplets and onto the workpiece,
wherein, in the second laser process, the seed layer is formed on the sidewall surface of the recess; and
performing a plating process using the seed layer as a seed to form a conductive feature within the recess.
2. The method of claim 1 , wherein the workpiece comprises a glass substrate.
3. The method of claim 1 , wherein the seed layer comprises copper.
4. The method of claim 1 , wherein performing the plating comprises performing an electroless plating process.
5. The method of claim 1 , wherein the conductive feature comprises copper.
6. The method of claim 1 , wherein the conductive feature has a width smaller than 12 μm.
7. The method of claim 1 , wherein the conductive feature comprises copper and wherein the conductive feature has a resistivity less than or equal to 1.5 times that of bulk copper.
8. The method of claim 1 , further comprising forming a through hole within the workpiece, wherein forming the seed layer comprises forming the seed layer within the through hole.
9. The method of claim 1 , wherein, in the second laser process, the beam of laser energy has a wavelength shorter than 550 nm.
10. The method of claim 1 , wherein, in the second laser process, the beam of laser energy is characterized by a pulse repetition rate less than 200 kHz and an average power less than 20 W.
11. The method of claim 1 , wherein the donor structure is spaced apart from the workpiece during formation of the seed layer.
12. The method of claim 1 , wherein the beam of laser energy directed in the second laser process is a pulsed beam of laser energy.
13. The method of claim 1 , wherein a quasi-continuous wave (QCW) laser is employed to provide the beam of laser energy directed in the second laser process.
14. The method of claim 1 , wherein the conductive feature is a wire mesh.
15. The method of claim 1 , wherein the workpiece and the conductive features exhibit an optical transmission greater than or equal to 90%.
16. The method of claim 1 , wherein the workpiece is flexible.
17. The method of claim 1 , wherein the recess further includes a bottom surface extending from the sidewall surface,
wherein, in the second laser process, the seed layer is formed on the bottom surface of the recess.
18. The method of claim 1 , wherein the second laser process further includes forming the seed layer outside the recess, the method further comprising:
removing the seed layer outside the recess before performing the plating process.
19. The method of claim 1 , wherein the workpiece comprises a main surface and wherein the recess extends into the workpiece from the main surface,
wherein a surface defining the recess is rougher than the main surface.
20. A method, comprising:
in a first laser process, directing a beam of laser energy to a workpiece to form a through hole within the workpiece;
in a second laser process, forming a seed layer within the through hole, wherein forming the seed layer includes directing a beam of laser energy onto a seed material, wherein forming the seed layer comprises:
providing a donor structure comprising a carrier substrate that is transparent to the beam of laser energy and a donor film, wherein the donor film faces toward the workpiece; and
directing the beam of laser energy through the carrier substrate to impinge a portion of the donor film such that at least a portion of the donor film impinged by the laser energy is transferred off from the carrier substrate as a plurality of liquid droplets and onto the workpiece; and
performing a plating process using the seed layer as a seed to form a conductive feature within the through hole.