Surface chemical mechanisms in atomic layer deposition of hard nitrides

Purpose and goal

Hard coatings extend the life of cutting edges in metalworking. One of the best materials to use is an alloy of aluminum nitride (AlN) and titanium nitride (TiN). Recently it was discovered that AlTiN can be deposited by CVD (chemical vapor deposition), this opens new possibilities but requires that the CVD process can be controlled. At MAX IV, we can study how a surface changes when molecules bind to it. By alternately pulsing in metal and nitrogen, we can study how the material slowly grows. Through measurements at MAX IV, we hope to control the CVD of AlTiN better.

Expected effects and result

Through the measurements at MAX IV, we hope to be able to build a model for how the surface chemistry in the CVD process for AlTiN works at the atomic level. With this model, we hope to control the CVD process in a better way, with less trail-and-error, to deposit AlTiN with the same ratio of Al to Ti throughout the CVD reactor. Such a well-controlled CVD process is necessary to produce AlTiN-coated cutting edges in a CVD process.

Planned approach and implementation

We will use our results in our ongoing research as we study a time-resolved form of CVD, ALD, or atomic layer deposition, for the deposition of AlTiN. We have therefore already developed ALD processes for AlN and TiN, and by mixing them we have also done ALD of AlTiN. We will study the surface chemistry of these ALD processes at MAX IV as a way to mimic the industrial CVD processes for AlTiN. At MAX IV, we will use x-ray photoelectron spectroscopy (XPS) to study the chemical bonds on the surface.