Silicon-Controlled Rectifier With Adjustable Holding Voltage and Strong Radiation Tolerance for ESD Protection

A novel silicon-controlled rectifier (SCR) device is proposed to achieve adjustable holding voltage (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V} _{\text {h}}$ </tex-math></inline-formula>) and strong radiation tolerance. The proposed SCR devices are fabricated in 0.18-<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula> m silicon-on-insulator (SOI) technology by inserting the very shallow trench isolation (VSTI) with different lengths in the n-well between the anode region and polysilicon. The adjustable <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V} _{\text {h}}$ </tex-math></inline-formula> ranging from 2.0 to 4.8 V is achieved by changing the length of VSTI from 0.3 to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3~\mu $ </tex-math></inline-formula> m. The influence of total ionizing dose (TID) on VSTI-SCR devices is investigated by experiments and simulations, and strong radiation tolerance up to 500 krad(Si) is proved for the VSTI-SCRs. It is concluded that its triggering voltage decreases by about 19%–31% with the radiation dose increase from 0 to 500 krad(Si), which is beneficial for the operation of VSTI-SCR devices. <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V} _{\text {h}}$ </tex-math></inline-formula> decreases by approximately 15%, which is overlapped by the ESD-design window of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.2\times {V}_{\text {DD}}$ </tex-math></inline-formula>–<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.8\times {V}_{\text {BD}}$ </tex-math></inline-formula>. Whereas, as the length of VSTI increases, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V} _{\text {h}}$ </tex-math></inline-formula> elevates and the effect of TID on <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V} _{\text {h}}$ </tex-math></inline-formula> of SCR devices remains almost unchanged, which means that the latch-up risk of VSTI-SCR induced by TID could be eliminated by broadening VSTI length properly.