Advanced Image-Spectrum Technique: The Investigation of Dielectric Property and Thermal Stability of Low-k Material in Cu Metallization

• Main Authors: Shen-Chuan Lo, 羅聖全
• Other Authors: Ji-Jung Kai
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/47224646887139034119

博士 === 國立清華大學 === 工程與系統科學系 === 91 === In this thesis, we developed an advanced microscopy technique：image-spectrum technique to study the dielectric property and thermal stability of Black DiamondTM dielectric materials for copper metallization. In my dissertation, I used newly developed signal processing methods to improve the capability of quantitative analysis of image spectrum. FFT interpolation and maximum entropy deconvolution were successfully used to solve the two problems：under-sampling and loss of energy resolution in image-spectrum technique, respectively. Based on novel signal-processing technique, the image-spectrum technique can extract two-dimensional property image from nanometer area of materials such as dielectric constant map and bang gap map. The novel Black DiamondTM a low-k material designed for copper metallization was used as a demo example. Since the analysis of the dielectric function is sensitive to the local thickness of the specimen using Kramers-Kronig analysis, we also developed a new method to quantitatively determine thickness of a wedge sample for low-k materials. We have determined the thickness of the Black DiamondTM low-k material using extrapolated thickness method from the materials of known dielectric constant. The experimentally determined dielectric constant of Black DiamondTM is 2.7±0.3 and very close to the reference value (2.5~2.8). The image-spectrum technique can extract basic materials properties from low-loss and high-loss electron energy region respectively such as band gap、dielectric function and bonding structure. This technique has been successfully extracted materials properties from low-loss electron energy region. However the application of this technique in high-loss region application has several difficulties such as：(1).energy drift (2).spatial( specimen ) drift (3).defocus of energy filtered image sand (4).recorded intensity stability must be overcome. Finally, the dielectric multiplayer was annealed at 250℃、350℃、450℃ respectively, in furnace vacuum with 8×10-6 torr for 1 hour to study the thermal effect on dielectric property of Black DiamondTM. The dielectric constant of Black DiamondTM increased as the annealing temperature increased. After annealed at 450℃, the dielectric constant of Black DiamondTM low-k material was increased from 2.7 to 3.5. We concluded that the bonding structure of the Black DiamondTM low-k material has been changed after thermal process and the dielectric property of Black DiamondTM shifted that of SiO2. The reason of dielectric constant of Black DiamondTM increased is the decreased of Si-CH3 bonding or C-H bonding broke during high temperature annealed. The development of new signal processing method：FFT interpolation and MEM deconvolution can rapidly and accurately extract two-dimensional property image such as dielectric constant map and band gap map. The new wedge dielectric constant measurement can measure the dielectric constant of dielectric materials in pattern sample. Advanced image-spectrum technique can combine with conventional EELS analysis, therefore the dielectric property and thermal stability of Black DiamondTM dielectric materials for copper metallization can be realized.