Scanning Electron Beam Facilitated Identification/Repair of Open Conductors in Trench Capacitor Technology
Original Publication Date: 1987-Oct-01
Included in the Prior Art Database: 2005-Feb-02
A method is reported for in-line testing of trench strap integrity using scanning electron microscope (SEM) image enhancement of unstrapped trenches in conjunction with molecular beam deposition of conductor material or laser spot annealing to repair partially good semiconductor chips. In certain CMOS (complementary metal-oxide semiconductor) memory arrays, enhanced storage capacitor storage is provided by trenches etched in silicon. The trench walls are coated with a dielectric, and the trench is filled with polysilicon, as shown in the figure. Contact to the "upper plate" of the capacitor storage node is made through a conductive strap leading from the storage node source/drain to the trench. If the strap does not form, storage capacitance is insufficient to store readable information.