Method for making a light-activated line-operable zero-crossing switch including two lateral transistors, the emitter of one lying between the emitter and collector of the other

A monolithic bi-directional thyristor switch with two power terminals, comprising:

• a first vertical transistor having an emitter, a base, and a collector region;
• a first lateral transistor of opposite type to said first vertical transistor and having an emitter, a base, and a collector region, and wherein said base region of said first vertical transistor and said collector region of said first lateral transistor are common, and said collector region of said first vertical transistor and said base region of said first lateral transistor are common, and wherein said first lateral transistor and first vertical transistor form a first thyristor wherein said emitter region of said first lateral transistor forms a first terminal of said first thyristor, said emitter region of said first vertical transistor forms a second terminal of said first thyristor, and said base region of said vertical transistor forms a gate of said first thyristor;
• a second vertical transistor of the same type as said first vertical transistor and having an emitter, a base, and a collector region;
• a second lateral transistor of opposite type to said second vertical transistor, and having an emitter, a base, and a collector region, and wherein said base region of said second vertical transistor and said collector region of said second lateral transistors are common, and said collector region of said second vertical transistor and said base region of said second lateral transistor are common, and wherein said second lateral transistor and second vertical transistor form a second thyristor wherein said emitter region of said second vertical transistor forms a first terminal of said second thyristor, said emitter region of said second lateral transistor forms a second terminal of said second thyristor, and said base region of said vertical transistor forms a gate of said second thyristor;
• wherein said collector regions of said first and second vertical transistors form a common semiconductor region;
• wherein said emitter region of said first lateral transistor is located between said emitter region and said collector region of said second lateral transistor, and said emitter region of said second lateral transistor is located between said emitter region and collector region of said first lateral transistor;
• and
• wherein said first terminal of said first thyristor is coupled to said first terminal of said second thyristor and said second terminal of said first thyristor is coupled to said second terminal of said second thyristor, said coupled terminals forming said two power terminals of said bi-directional switch.