Improving stress stability in low-pressure chemical vapor deposited silicon dioxide films by ion implantation

• Ion implantation is introduced to improve LPCVD SiO2 film stress stability.
• The film stress changes with implantation energies due to the atomic collisions.
• The stress evolution can be affected by implantation ion types and doses.
• P+ ion is more appropriate to improve stress stability than As+ and B+ ions.

The stress state of low-pressure chemical vapor deposition (LPCVD) silicon dioxide (SiO2) films fluctuates upon aging due to the ambient moisture. The related variation of the SiO2 films is a key factor of device reliability. In this study, ion implantation is introduced to improve film stress stability. The stress state modified by ion implantation is discussed in detail and an analytical model is presented. The evolution of the stress in as-deposited and P+-, As+-, and B+-implanted LPCVD SiO2 films upon aging is investigated, and the bonding nature of the films is also studied to provide insight into the physical mechanisms involved. It is demonstrated that low implantation energy slightly modifies the stress in films. In addition, P+ ion is the most appropriate impurity ion to improve film stress stability, and the stress in P+-implanted LPCVD SiO2 film can be stabilized with a low tensile stress of 67 MPa when the film is implanted at 15 keV with a dose of 1 × 1015 cm− 2.