Method of manufacturing magnetic memory devices
View Patent ↗A method of manufacturing a plurality of magnetoresistive memory element having a dielectric thermal buffer layer between a thin top electrode of the magnetic tunnel junction (MTJ) element and a bit line, and a bit-line VIA electrically connecting the top electrode and the bit line having a vertical distance away from the location of the MTJ stack. In a laser thermal annealing, a short wavelength of a laser has a shallow thermal penetration depth and a high thermal resistance from the bit line to the MTJ stack only causes a temperature rise of the MTJ stack being much smaller than that of the bit line. As the temperature of the MTJ element during the laser thermal annealing of bit line copper layer is controlled under 300-degree C., possible damages on MTJ and magnetic property can be avoided.
1. A method of manufacturing a magnetoresistive memory element comprising:
deposit and pattern a bottom electrode on a surface of an dielectric substrate connecting to a VIA of a select transistor;
deposit and pattern a magnetic tunnel junction (MTJ) stack;
refill a dielectric layer surrounding the MTJ stack and conduct a chemical mechanical polishing (CMP) process to flatten the top surface;
deposit and pattern a top electrode on the surface of the MTJ stack and surrounding dielectric layer;
deposit a dielectric thermal barrier layer on the top surface of the top electrode;
open a bit-line VIA in the dielectric thermal barrier layer on the surface of the top electrode and having a vertical distance away from the MTJ stack;
deposit a seed layer and electroplate a bit line in the bit-line VIA and on the top surface of the dielectric thermal barrier layer;
conduct a CMP process to flatten the top surface of the bit line and followed by a deposition of a dielectric protective layer;
conduct a pulsed short wavelength laser thermal annealing on the bit line;
wherein said laser thermal annealing generates a temperature rise of said bit line above 400-degree C.; and
wherein during said laser thermal annealing, the maximum temperature rise of said MTJ stack is below 300-degree C.