Chartered Semiconductor Manufacturing Ltd (corporation)

Keng-Foo Lo

Jun Song

Guang Ping Hua

Described is a MOS gate-controlled SCR (UGSCR) structure with a U-shaped gate (UMOS) for an ESD protection circuit in an IC device which is compatible with shallow trench isolation (STI) and self-aligned silicide (salicide) fabrication technology. The UMOS gate is located in a p-substrate and is surrounded by an n-well on either side. Adjacent to one side of the UMOS gate, a first n&plus; diffusion is formed which straddles the first n-well. The n&plus; diffusion together with a p&plus; pickup diffused next to it form the cathode of the SCR (thyristor). Adjacent to the other side of the UMOS gate, a second n&plus; and p&plus; diffusion are formed in a second n-well. The second n&plus; and p&plus; diffusion together with the UMOS gate form the anode of the SCR and the input terminal of the circuit to be protected. The SCR is formed by the first n&plus; diffusion/n-well (cathode), the p-substrate, the second n-well and the second p&plus;/n&plus; diffusion (anode). A latchup immune circuit is achieved by creating a U-shaped gate structure which is lined with a thick gate oxide&mdash;similar to a field oxide&mdash;under the poly gate.

Umos-like gate-controlled thyristor structure for ESD protection

Described is a method of creating a MOS gate-controlled SCR (UGSCR) structure with a U-shaped gate (UMOS) for an ESD protection circuit in an IC device which is compatible with shallow trench isolation (STI) and self-aligned silicide (salicide) fabrication technology. The UMOS gate is located in a p-substrate and is surrounded by an n-well on either side. Adjacent to one side of the UMOS gate, a first n&plus; diffusion is formed which straddles the first n-well. The n&plus; diffusion together with a p&plus; pickup diffused next to it form the cathode of the SCR (thyristor). Adjacent to the other side of the UMOS gate, a second n&plus; and p&plus; diffusion are formed in a second n-well. The second n&plus; and p&plus; diffusion together with the UMOS gate form the anode of the SCR and the input terminal of the circuit to be protected. The SCR is formed by the first n&plus; diffusion/n-well (cathode), the p-substrate, the second n-well and the second p&plus;/n&plus; diffusion (anode). A latchup immune circuit is achieved by creating a U-shaped gate structure which is lined with a thick gate oxide&mdash;similar to a field oxide&mdash;under the poly gate.

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Keng-Foo Lo