The detection and investigation of poly line leakage by electron-beam inspection

The study aims at the inline detection of invisible defects of poly line leakage. The defect was induced by extreme tiny residue at the bottom of the poly line of the SiGe loop process. A novel electron beam (E-beam) scan method was developed. And with voltage contrast (VC) inspection of E-beam, poly line leakage with bright VC (BVC) was detected just post SiGe deposition (DEP) nitride (SIN) hard mask (HM) remove (RM). The failure model of tiny SiGe residue was setup and established. The impacted factors of the defect were also discussed, including spacer SIN and SiGe HM SiN thickness, the step height of the AA and STI, the OX loss induced by SiGe ETCH clean/SiGe DEP pre-clean even the wet strip of low dose drain (LDD) implantation (IMP) loop. The corresponding improvement actions including controlling OX loss, increasing the thickness of SiGe SIN HM and reducing the step height of AA and STI were executed. The poly line BVC defects obviously trended low accordingly.