| AVS 58th Annual International Symposium and Exhibition | |
| Plasma Science and Technology Division | Thursday Sessions |
| Session PS+SS-ThA |
| Session: | Plasma Surface Interactions (Fundamentals & Applications) II |
| Presenter: | Freek Molkenboer, TNO, Netherlands |
| Authors: | F.T. Molkenboer, TNO, Netherlands N.B. Koster, TNO, Netherlands A.J. De Jong, TNO, Netherlands J.C.J. van der Donck, TNO, Netherlands A.M.C.P. de Jong, TNO, Netherlands O. Kievit, TNO, Netherlands |
| Correspondent: | Click to Email |
In this presentation we will report our work on the design and experimental results of a plasma unit to clean the backside of substrates. Backside contamination of substrates can limit the quality of the front side process. Outgassing of backside contaminants can influence the front side process, or particles on the backside can influence the image quality in a wafer stepper. The complete backside cleaning unit uses three modules to remove both organic and an-organic particles as well as organic contamination layers. This is all done in a high vacuum environment. To remove particles we will use a commercial available tacky roller. The second method to remove particles uses an UV lamp that will charge the particles on the substrate and a strong electric field to remove these charged particles from the substrate.
To remove organic contamination, for example resist residues after processing, we will use a RF plasma. The design of the RF plasma unit makes continuous cleaning over a large surface area possible. The gas in the plasma unit itself will have a pressure of 0.5 to 1 mbar. The vacuum chamber in which the complete backside cleaning unit is placed will have a pressure of around 10-3 mbar when the plasma unit is in use. This difference in pressure is achieved by placing the inlet of the gas in the RF plasma unit and making the outlet to the vacuum chamber very small. This design leads to a large expansion of the gas at the outlet of the RF plasma unit. The benefits of this design are that the pressure within the RF plasma unit is high enough for creating plasma and the pressure within the vacuum chamber is low enough to prevent that the whole vacuum chamber is filled with plasma.
This project focuses on backside cleaning of wafers within the "European Equipment & Materials Initiative for 450 mm" (EEMI450) under the ENIAC research program.
Within this European project, TNO is responsible for addressing contamination control issues. The concept of this backside cleaning unit can also be used to clean substrates used in roll to roll lines for solar cells or other processes that need continuous cleaning at high speed.