TY - JOUR

T1 - Fusion bonding of silicon nitride surfaces

A1 - Reck,Kasper

A1 - Østergaard,Christian

A1 - Thomsen,Erik Vilain

A1 - Hansen,Ole

AU - Reck,Kasper

AU - Østergaard,Christian

AU - Thomsen,Erik Vilain

AU - Hansen,Ole

PB - Institute of Physics Publishing

PY - 2011

Y1 - 2011

N2 - While silicon nitride surfaces are widely used in many micro electrical mechanical system devices, e.g. for chemical passivation, electrical isolation or environmental protection, studies on fusion bonding of two silicon nitride surfaces (Si3N4–Si3N4 bonding) are very few and highly application specific. Often fusion bonding of silicon nitride surfaces to silicon or silicon dioxide to silicon surfaces is preferred, though Si3N4–Si3N4 bonding is indeed possible and practical for many devices as will be shown in this paper. We present an overview of existing knowledge on Si3N4–Si3N4 bonding and new results on bonding of thin and thick Si3N4 layers. The new results include high temperature bonding without any pretreatment, along with improved bonding ability achieved by thermal oxidation and chemical pretreatment. The bonded wafers include both unprocessed and processed wafers with a total silicon nitride thickness of up to 440 nm. Measurements of bonding strength, void characterization, oxidation rate and surface roughness are also presented. Bonding strengths for stoichiometric low pressure chemical vapor deposition Si3N4–Si3N4 direct fusion bonding in excess of 2 J cm−2 are found. The stoichiometry is verified indirectly through refractive index and intrinsic stress measurements. The importance of surface oxide in Si3N4–Si3N4 fusion bonding is investigated by x-ray photoelectron spectroscopy measurements.

AB - While silicon nitride surfaces are widely used in many micro electrical mechanical system devices, e.g. for chemical passivation, electrical isolation or environmental protection, studies on fusion bonding of two silicon nitride surfaces (Si3N4–Si3N4 bonding) are very few and highly application specific. Often fusion bonding of silicon nitride surfaces to silicon or silicon dioxide to silicon surfaces is preferred, though Si3N4–Si3N4 bonding is indeed possible and practical for many devices as will be shown in this paper. We present an overview of existing knowledge on Si3N4–Si3N4 bonding and new results on bonding of thin and thick Si3N4 layers. The new results include high temperature bonding without any pretreatment, along with improved bonding ability achieved by thermal oxidation and chemical pretreatment. The bonded wafers include both unprocessed and processed wafers with a total silicon nitride thickness of up to 440 nm. Measurements of bonding strength, void characterization, oxidation rate and surface roughness are also presented. Bonding strengths for stoichiometric low pressure chemical vapor deposition Si3N4–Si3N4 direct fusion bonding in excess of 2 J cm−2 are found. The stoichiometry is verified indirectly through refractive index and intrinsic stress measurements. The importance of surface oxide in Si3N4–Si3N4 fusion bonding is investigated by x-ray photoelectron spectroscopy measurements.

U2 - 10.1088/0960-1317/21/12/125015

DO - 10.1088/0960-1317/21/12/125015

JO - Journal of Micromechanics and Microengineering

JF - Journal of Micromechanics and Microengineering

SN - 0960-1317

IS - 12

VL - 21

SP - 125015

ER -