SESIBON: Sensor encapsulation by silicon bonding

• Unité de recherche: PCRD EU
• Numéro de projet: 99.0294
• Titre du projet anglais: SESIBON: Sensor encapsulation by silicon bonding

Mots-clé (Anglais)

Anodic bonding; packaging; silicon

Autre Numéro de projet (Anglais)

EU project number: G1RD-CT-99-00002

Programme de recherche (Anglais)

EU-programme: 5. Frame Research Programme - 1.3.1 Innovative products, processes and organization

Description succincte (Anglais)

See abstract

Partenaires et organisations internationales (Anglais)

Sensonor asa (NO), Okmetic Ltd. (FIN), SAAB Microtech (S), Danfoss A/S (DK), Mikroelektronik Centret (DK), Chalmers University of Technology (S)

Résumé des résultats (Abstract) (Anglais)

The project Sensor Encapsulation by Silicon Bonding (SESiBon) aims at low-cost reliable products and processes using advanced wafer bonding. The application area is for microsystems, a rapidly evolving market.
IMT project title: Metal to glass anodic bonding for robust fluidic interconnects
Technology: Metal to glass anodic Bonding
Methods for combining fluid connectors with anodic bonding have been explored for the realization of a flow sensor demonstrator. Work has been in progress to assess anodic bonding of metal to glass for this purpose. The experiments have shown that stable bondings can be achieved between Pyrex and alloys with a similar thermal expansion coefficient like Kovar and Alloy-42. Water jet machining was a suitable tool for dicing and drilling purposes. Metal polishing using an aluminum oxide slurry provided a surface roughness suitable to perform the anodic bonding of the polished metal surface to Pyrex glass substrates. The bondings performed at temperatures of and higher than 300°C exhibited a high strength and tightness to liquid at a pressure of 1 bar. Bondings performed at a temperature between 300 and 375°C presented a minimised residual stress. Annealing of the bonded samples decreased the residual stress to a stabilised value. Wafers made of Kovar and Alloy 42 were bonded succesfully to wafers of Pyrex to address wafer level packaging.
Demonstrator: Liquid flow sensor encapsulation
Metal to glass anodic bonding was used to integrate robust fluidic connectors to a liquid flow sensor. Experiments have shown that stable bondings can be achieved between Pyrex and alloys with a similar thermal expansion coefficient like Kovar and Alloy-42. The bondings exhibited a small residual stress, a high strength, and a tightness to liquid at a pressure of at least 1 bar. Metal to glass anodic bonding was used to package a piezoresistive Silicon/Pyrex sensor, eliminating the use of glue. Sensors were anodically bonded on polished Kovar and Alloy 42 3 mm-thick plates, in which holes were made. Short tubes in stainless steel were screwed or laser soldered in the holes and used as fluidic connectors. Electrical interconnections were integrated on the metallic plate by anodically bonding a pyrex plate with aluminium lines or by gluing a ceramic plate with printed metallic lines. Temperature coefficient of the offset (TCO), of the resistance (TCR) and of the sensitivity (TCS) of the flow sensor were characterized. It has been shown that the flow sensor in this packaging configuration fulfils the specifications.

Références bases de données (Anglais)

Swiss Database: Euro-DB of the
State Secretariat for Education and Research
Hallwylstrasse 4
CH-3003 Berne, Switzerland
Tel. [phone]
Swiss Project-Number: 99.0294