TY - GEN
T1 - High sensitivity capacitive humidity sensor with a novel polyimide design fabricated by mems technology
AU - Kim, Ji Hong
AU - Hong, Sung Min
AU - Lee, Jang Sub
AU - Moon, Byung Moo
AU - Kim, Kunnyun
PY - 2009
Y1 - 2009
N2 - High sensitivity capacitive humidity sensor based on novel designed PI with cavity structure fabricated by MEMS technology is presented in this paper. The humidity sensor consists of a substrate with a cavity, a bottom electrode, a sensing layer, and a comb-shaped top electrode with branches. The cavity structure of the substrate was formed to protect the sensing material and improve reliability. PI was employed for the sensing layer due to its low hysteresis, good linearity, high sensitivity and high resistance to most chemicals. The comb-shaped top electrode was designed to have 50% fill factor with branches and the coated PI was etched by using O2 plasma asher in accordance with the top electrode passivation. This structure could improve the sensitivity and the response time of the humidity sensor due to larger area of contact between the PI and vapor, and shorter pathway of vapor absorption. The humidity sensor was fabricated on a 4 inch silicon wafer by MEMS technology. The humidity sensor with the etched PI showed a high sensitivity of 350 fF/%RH and the response time of 40sec from room humidity condition to 900/oRH. These are more improved results compared with values before PI etching, which are sensitivity of 303 fF/%RH and response time of 122 sec. Further characterizations were carried out to measure the hysteresis and the stability. The humidity sensor showed the hysteresis of 1.3% and maintained stable capacitance values with maximum 0.17% error rate, that are enough values to be used as a reliable humidity sensor in various applications.
AB - High sensitivity capacitive humidity sensor based on novel designed PI with cavity structure fabricated by MEMS technology is presented in this paper. The humidity sensor consists of a substrate with a cavity, a bottom electrode, a sensing layer, and a comb-shaped top electrode with branches. The cavity structure of the substrate was formed to protect the sensing material and improve reliability. PI was employed for the sensing layer due to its low hysteresis, good linearity, high sensitivity and high resistance to most chemicals. The comb-shaped top electrode was designed to have 50% fill factor with branches and the coated PI was etched by using O2 plasma asher in accordance with the top electrode passivation. This structure could improve the sensitivity and the response time of the humidity sensor due to larger area of contact between the PI and vapor, and shorter pathway of vapor absorption. The humidity sensor was fabricated on a 4 inch silicon wafer by MEMS technology. The humidity sensor with the etched PI showed a high sensitivity of 350 fF/%RH and the response time of 40sec from room humidity condition to 900/oRH. These are more improved results compared with values before PI etching, which are sensitivity of 303 fF/%RH and response time of 122 sec. Further characterizations were carried out to measure the hysteresis and the stability. The humidity sensor showed the hysteresis of 1.3% and maintained stable capacitance values with maximum 0.17% error rate, that are enough values to be used as a reliable humidity sensor in various applications.
KW - Capacitive humidity sensor
KW - Humidity sensor
KW - MEMS
KW - Polyimide
UR - http://www.scopus.com/inward/record.url?scp=70349706249&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=70349706249&partnerID=8YFLogxK
U2 - 10.1109/NEMS.2009.5068676
DO - 10.1109/NEMS.2009.5068676
M3 - Conference contribution
AN - SCOPUS:70349706249
SN - 9781424446308
T3 - 4th IEEE International Conference on Nano/Micro Engineered and Molecular Systems, NEMS 2009
SP - 703
EP - 706
BT - 4th IEEE International Conference on Nano/Micro Engineered and Molecular Systems, NEMS 2009
T2 - 4th IEEE International Conference on Nano/Micro Engineered and Molecular Systems, NEMS 2009
Y2 - 5 January 2009 through 8 January 2009
ER -