Patent ID: 8188563
Filing Date: 2012-05-29
Classification: G01S,H01L,Y02E

Abstract:
1. A single photon avalanche diode (SPAD) device, comprising: a substrate doped to exhibit a first type conductivity and having a top substrate surface and a bottom substrate surface, the first type conductivity being either one of a n-type conductivity and an opposite p-type conductivity; a well region located in the substrate from the top substrate surface and doped to exhibit a second, opposite type conductivity to leave a substrate region of the first type conductivity in the substrate between the well region and the bottom substrate surface, wherein the bottom of the well region and the top of the substrate region interfaces to form a deep p-n junction; a trench ring formed in the well region to create a trench from the top substrate surface that surrounds a first portion of the well region and leave a second portion of the well region outside the trench ring, the trench ring filled with an insulator material to form a guard ring to spatially confine the first portion of the well region; a shallow region in the first portion of the well region inside the guard ring that is doped to exhibit the first type conductivity to have a depth from the top substrate surface less than a depth of the guard ring, a bottom part of the shallow region interfacing with a remaining of the first portion of the well region in the second type conductivity to form a shallow p-n junction; and a quenching resistive element electrically coupled to the shallow p-n junction to produce a large resistance that makes a voltage across the shallow p-n junction to be less than a breakdown voltage of the shallow p-n junction when the shallow p-n junction is electrically reversely biased to cause an avalanche breakdown process upon absorption of a photon in the shallow p-n junction; wherein the quenching resistive element comprises an active recharge circuit electrically coupled in series to the shallow p-n junction to control quenching and recharging the shallow p-n junction in the avalanche ionization process, the active recharge circuit comprising: a quenching transistor whose source or drain is electrically connected to the shallow p-n junction, the quenching transistor being electrically controlled to exhibit the large resistance; a recharge transistor whose source or drain is electrically connected to the shallow p-n junction, the recharge transistor being electrically controlled to exhibit a small resistance less than the large resistance; and a control circuit comprising a control transistor electrically coupled to the quenching transistor and the recharge transistor and operable in response to a sensing voltage at the shallow p-n junction to