Characterization of chromium thin films by sputter deposition

In this study, a systematic investigation on the deposition of Cr–CrOx bi-layer film was performed by magnetron DC sputtering. The X-ray photoelectron spectrometer (XPS) examining the bare Cr film showed that the peaks of Cr 2P3/2 and Cr 2P1/2 appeared in the Cr thin film associated with the presence of a 12 nm oxide layer. The transmission was reduced to zero as the Cr film exceeded 100 nm in thickness. The reflection saturated at a value of ≈55% when the thickness of the Cr film reached 30 nm. The optical density exceeded 3.50 with a Cr film thickness over 150 nm. In order to reduce the reflection of the film to a level of ≤4%, a Cr–CrOx bi-layer thin film was prepared. Overall, a Cr–CrOx bi-layer film with the Cr layer 130 nm and the CrOx layer 40 nm in thickness reported a transmission of zero, a reflection of 3.82% and an optical density of 4.04, all meeting the requirements of anti-reflection black matrix (BM) for display applications.

► XPS results confirmed the presence of a 12 nm oxide layer in the bare Cr-film due to absorption.
► A film with Cr film 130 nm and CrOx film 40 nm in thickness qualified for use in anti-reflection BM.
► They reported a transmission of zero, a reflection of 3.82% and an optical density of 4.04.