A process for direct integration of a thin-film silicon p-n junction diode with
a magnetic tunnel junction for use in advanced magnetic random access memory (MRAM)
cells for high performance, non-volatile memory arrays. The process is based on
pulsed laser processing for the fabrication of vertical polycrystalline silicon
electronic device structures, in particular p-n junction diodes, on films of metals
deposited onto low temperature-substrates such as ceramics, dielectrics, glass,
or polymers. The process preserves underlayers and structures onto which the devices
are typically deposited, such as silicon integrated circuits. The process involves
the low temperature deposition of at least one layer of silicon, either in an amorphous
or a polycrystalline phase on a metal layer. Dopants may be introduced in the silicon
film during or after deposition. The film is then irradiated with short pulse laser
energy that is efficiently absorbed in the silicon, which results in the crystallization
of the film and simultaneously in the activation of the dopants via ultrafast melting
and solidification. The silicon film can be patterned either before or after crystallization.