title>INTRODUCTION
Optical constants (complex refractive index n, complex dielectric function ϵ, and reflection and absorption coefficients R and α) of materials are of great importance for optical metrology in the semiconductor industry.1,2 A high-performance complementary-metal-oxide-semiconductor process flow with 11 layers of metal requires about 75 photolayers and may contain up to 100 thickness measurements, most of them performed using spectroscopic ellipsometry.3 This technique has been described in various books with increasing levels of sophistication.4–7
Since most microelectronic devices are built on a Si wafer, the optical constants of Si and SiO2 are the most important ones and have been determined with greater accuracy than …show more content…
These techniques (and data resulting from them) are still the most useful today and have not been replaced by more modern methods, such as spectroscopic ellipsometry, which is not suitable for measuring small absorption coefficients below about 103 cm−1 (see Refs. 20 and 21). Above the band gap, the transmission measurements on thin films can be successful.22 Since about 1960, the complex dielectric function above the band gap has been determined by reflectance followed by Kramers–Kronig transformation,23 but such results are often plagued by systematic errors due to surface overlayers (including surface roughness) and the limited spectral range of the …show more content…
These pieces were then subjected to an ozone clean in a Novascan PSD Pro series digital UV ozone system utilizing a Hg vapor lamp. This cleaning was performed in an oxygen-enriched environment, achieved by allowing ultrapure (99.98%) oxygen to flow through the system for several minutes before sealing the chamber with the Hg lamp on and the sample on a heating stage held at 150 °C for 60 min, followed by a 30-min period of incubation with the lamp off and the sample cooling to room temperature. After the ozone clean, samples were cleaned ultrasonically for 20 min in deionized water, followed by 20 min in
Optical constants (complex refractive index n, complex dielectric function ϵ, and reflection and absorption coefficients R and α) of materials are of great importance for optical metrology in the semiconductor industry.1,2 A high-performance complementary-metal-oxide-semiconductor process flow with 11 layers of metal requires about 75 photolayers and may contain up to 100 thickness measurements, most of them performed using spectroscopic ellipsometry.3 This technique has been described in various books with increasing levels of sophistication.4–7
Since most microelectronic devices are built on a Si wafer, the optical constants of Si and SiO2 are the most important ones and have been determined with greater accuracy than …show more content…
These techniques (and data resulting from them) are still the most useful today and have not been replaced by more modern methods, such as spectroscopic ellipsometry, which is not suitable for measuring small absorption coefficients below about 103 cm−1 (see Refs. 20 and 21). Above the band gap, the transmission measurements on thin films can be successful.22 Since about 1960, the complex dielectric function above the band gap has been determined by reflectance followed by Kramers–Kronig transformation,23 but such results are often plagued by systematic errors due to surface overlayers (including surface roughness) and the limited spectral range of the …show more content…
These pieces were then subjected to an ozone clean in a Novascan PSD Pro series digital UV ozone system utilizing a Hg vapor lamp. This cleaning was performed in an oxygen-enriched environment, achieved by allowing ultrapure (99.98%) oxygen to flow through the system for several minutes before sealing the chamber with the Hg lamp on and the sample on a heating stage held at 150 °C for 60 min, followed by a 30-min period of incubation with the lamp off and the sample cooling to room temperature. After the ozone clean, samples were cleaned ultrasonically for 20 min in deionized water, followed by 20 min in