A vertical thyristor memory array including: a vertical thyristor memory cell, the vertical thyristor memory cell including: a p+ anode; an n-base located below the p+ anode; a p-base located below the n-base; a n+ cathode located below the p-base; an isolation trench located around the vertical thyristor memory cell; an assist gate located in the isolation trench adjacent the n-base wherein an entire vertical height of the assist gate is positioned within an entire vertical height of the n-base.

Disclosed is an electrostatic discharge protection device which includes a substrate including a first well having a first conductivity type and a second well surrounding the first well, first to fifth diffusion regions formed on the first well, and sixth and seventh diffusion regions formed on the second well. The second diffusion region surrounds the first diffusion region, the fourth diffusion region surrounds the fifth diffusion region, and the fifth diffusion region surrounds the second diffusion region and the fourth diffusion region. The sixth diffusion region surrounds the fifth diffusion region, and the seventh diffusion region surrounds the sixth diffusion region. The sixth and seventh diffusion regions are connected to an anode electrode, and the first to fifth diffusion regions are connected a cathode electrode.

A bidirectional power semiconductor device with full turn-off control in both current directions and improved electrical and thermal properties is provided, the device comprises a plurality of first gate commutated thyristor (GCT) cells and a plurality of second GCT cells alternating with each other, a first base layer of each first GCT cell is separated from a neighbouring second anode layer of a neighbouring second GCT cell by a first separation region, and a second base layer of each second GCT cell is separated from a neighbouring first anode layer of a neighbouring first GCT cell by a second separation region.

A vertical thyristor memory array including: a vertical thyristor memory cell, the vertical thyristor memory cell including: a p+ anode; an n-base located below the p+ anode; a p-base located below the n-base; a n+ cathode located below the p-base; an isolation trench located around the vertical thyristor memory cell; an assist gate located in the isolation trench adjacent the n-base wherein an entire vertical height of the assist gate is positioned within an entire vertical height of the n-base.

Memory arrays of vertical thyristor memory cells with SiGe base layers are described. The composition of the SiGe can be constant or varied depending upon the desired characteristics of the memory cells. The memory cells allow a compact structure with desirable low voltage operations.

Isolation between vertical thyristor memory cells in an array is improved with isolation regions between the vertical thyristor memory cells. The isolation regions are formed by electrically isolating cores surrounded by insulating material, such as silicon dioxide, in trenches between the memory cells. The electrically isolating cores may be tubes of air or conducting rods. Methods of constructing the isolation regions in a processes for manufacturing vertical thyristor memory cell arrays are also disclosed.

Methods and systems for reducing electrical disturb effects between thyristor memory cells in a memory array are provided. Electrical disturb effects between cells are reduced by using a material having a reduced minority carrier lifetime as a cathode line that is embedded within the array. Disturb effects are also reduced by forming a potential well within a cathode line, or a one-sided potential barrier in a cathode line.