Processability and electrical characteristics of glass substrates for RF wafer-...

• Author(s): Polyakov, A. ; Mendes, P. M. ; Sinaga, S. M. ; Bartek, M. ; Rejaei, B. ; Correia, J. H. ; Burghartz, J. N.
• Date: 2003
• Persistent ID: http://hdl.handle.net/1822/1950
• Origin: RepositóriUM - Universidade do Minho
• Subject(s): Wafer level packaging; Wafer bonding; Glass wafer processing
• Document Type: Conference Object
• Language: English

Description

Various types of glass substrates have been compared with respect to their suitability as a low-loss substrate in wafer-level chip-scale packaging for RF applications. Processability has been evaluated by fabrication of shallow and deep recesses using wet etching in HF (/H3PO4) solutions. Electrical characteristics (dielectric constant and attenuation) have been extracted from measurements on coplanar wave guides (CPWs) up to 10 GHz. Results show that Coming Pyrex #7740 glass provides optical quality of wet-etched deep recesses, but exhibit about 2 times higher electrical attenuation than Hoya SD-2. Pyrex #7740 and SD-2 are thermally matched to silicon and due to some alkali content, they are suitable for anodic bonding. The relatively high content of AL2O3 (~20%) in SD-2 is favorable for its electrical properties, but makes wet etching of deep recesses more difficult. The non-alkaline AF45, with CTE almost 2 times of Si (CTEAF45=4.5x10-6 k-1), is suitable for adhesive bonding and is difficult to pattern using wet etching. Its electrical attenuation is close to that of SD-2. The measured dielectric constants (at 6 GHz) for SD-2, Pyrex #7740 and AF45 are 4.7,5.9 and 6.1, respectively.