Berliner Glas manufactures super-flat wafer chucks
The trend of the semiconductor industry to always achieve higher integration densities as well as shrinking structural sizes places high demands on the characteristics of the chucks that hold the wafers during the lithography and inspection processes.
Berliner Glas , a supplier of high-precision, custom designed wafer chucks to the semiconductor industry, says it knows how to produce an ideally flat wafer chuck.
Besides thermal performance and thermal management, roughness of the surface, choice of materials as well as the contact area between wafer and wafer chuck are the key parameters in influencing the wafer chucks effective flatness. Usually this contact area is decreased as much as possible to lower particle sensitivity. This can be realised by a pin structure on the chuck surface.
In its Poster Presentation during the Poster Reception of the SPIE Advanced Lithography in San Jose, California, the Berliner Glas Group will address methods of designing and evaluating such a pin structure.
The Poster Session will take place on 25th February 2014 from 06:00 until 08:00 pm in Conv. Ctr. Hall 2.
The abstract of the presentation in below.
Super - flat wafer chucks: from simulation and testing to a complete 300mm wafer chuck with low wafer deformation between pins
Authors: Dr. Renate Mueller, Dr. Konstantin Afanasiev, Marcel Ziemann, Volker Schmidt
Berliner Glas is a privately owned, mid-sized manufacturer of precision opto-mechanics in Germany. One specialty of Berliner Glas is the design and production of high performance vacuum and electrostatic wafer chucks.
Driven by the need of lithography and inspection for smaller overlay values, we pursue the production of an ideally flat wafer chuck. An ideally flat wafer chuck holds a wafer with a completely flat backside and without lateral distortion within the wafer surface.
Key parameters in influencing the wafer chucks effective flatness are thermal performance and thermal management, roughness of the surface, choice of materials and the contact area between wafer and wafer chuck. In this presentation we would like to focus on the contact area. Usually this is decreased as much as possible to avoid sticking effects and the chance of trapped particles between the chuck surface and the backside of the wafer.
This can be realised with a pin structure on the chuck surface. Making the pins smaller and moving pins further apart from each other makes the contact area ever smaller but also adds new challenges to achieve a flat and undistorted wafer on the chuck. We would like to address methods of designing and evaluating such a pin structure.
This involves not only the capability to simulate the ideal pattern of pins on the chuck's surface, for which we will present 2D and 3D simulation results. As well, we would like to share first results of our functional models. Finally, measurement capability has to be ensured, which means improving and further development of Fizeau flatness test interferometers
The Berliner Glas Group will also participate in the SPIE Advanced Lithography as an exhibitor and will inform about the broad spectrum of its solutions at its booth #230. The exhibition will open on 25th and 26th February 2014.
