Silicon surface treatment by atmospheric large remote plasma for heterogeneous material integration*

Hydrophilic bonding is commonly used in semiconductor heterogeneous material integration for large-scale photonic integrated circuits. In this process, plasma irradiation is used in a vacuum apparatus for surface hydrophilization. That requires batch processing in a vacuum chamber.

To solve these problems, we have proposed inline process that integrates a hydrophilic treatment by plasma irradiation using atmospheric plasma and a temporary bonding device. Up to now, we have proven such plasma treatment showed a good processing effect. However, it required time to process large areas because of its small irradiation port.

In this study, an atmospheric large-sized remote plasma source that can hydrophilize a 12-inch semiconductor wafer in a one-dimensional scan was developed. The plasma source has an irradiation slit of 1 x 349 mm and low temperature plasma blow out from the slit. By applying a radio frequency of 27.12 MHz to the electrodes inside the device and flowing the plasma generating gas at a rate of around 20 L/min, stable helium and argon plasma could be generated.

To investigate the cleanliness of this device and the plasma jet source, the number of particles of various diameters generated in the plasma sources were measured using a particle counter. Experiments on hydrophilization of silicon surfaces were also conducted using these plasma devices.