Development of Crystallographic Texture in RF Sputter Deposited CoCrTa/Cr Thin Films
- PDF / 387,337 Bytes
- 6 Pages / 420.48 x 639 pts Page_size
- 74 Downloads / 185 Views
DEVELOPMENT OF CRYSTALLOGRAPHIC TEXTURE IN RF SPUTTER DEPOSITED CoCrTa/Cr THIN FILMS Y. C. FENG, D. E. LAUGHLIN and D. N. LAMBETH*, Department of Materials Science and Engineering, *Department of Electrical and Computer Engineering, Data Storage System Center, Carnegie Mellon University, Pittsburgh, PA 15213 ABSTRACT It is well known that Cr sputtered on glass or NiP/Al substrates has either the (002) or (110) crystallographic texture (depending on the substrate temperature) and that the Co-alloy layers which are deposited on the Cr underlayers have either the (1120) or (10-1) textures respectively. However, the dependence of the crystallographic textures on other sputtering parameters is not clear. We report here on the study of the dependence of crystallographic textures of CoCrTa/Cr films on substrate bias. It is found that both Cr (110) and Cr (002) textures can form at elevated temperature, depending on the substrate bias. The development of the crystallographic texture is discussed with a model. It is also found that the epitaxy of CoCrTa layer depends on the sputtering conditions of both the Cr and the CoCrTa layers. The extrinsic magnetic properties (such as Hc, S and S*) of thin films with various textures are also presented. By controlling the sputtering procedure, the effects of crystallographic textures on magnetic properties were separated from the effects of film morphology. I. INTRODUCTION Sputtered CoCrTa thin films on Cr underlayers are one of the most promising candidates for longitudinal recording media, 1,2 due to their high in-plane coercivity and low recording noise. 3 It is believed that the Cr underlayer enhances the magnetic properties by facilitating the growth of Co-alloy grains with a crystallographic plane of either hcp (1120) or (1011) parallel to the film surface, 4 This causes the c-axis to lie nearly in the film surface. Therefore, understanding the dependence of crystallographic texture of CoCrTa/ Cr thin films on sputtering condition is of great importance. Previous work regarding the crystallographic texture of Co-alloy/Cr has been summarized by T. Ohno et al.5 It is well known that sputtered Cr thin films have either (110) or (002) texture, 5 -7 depending on the substrate temperature. When deposited without substrate preheating, the Cr layers have the (110) texture, while when deposited at elevated temperatures they tend to have the (002) texture. However, the dependence of crystallographic texture on other sputter parameters is not clear. In this work, we have studied the dependence of the crystallographic texture of RF sputter deposited Cr underlayer on substrate bias. We find that when it is deposited at room temperature, the Cr layer always has the (110) texture and when deposited at elevated temperature, the Cr layer has either the Cr (002) or the Cr (110) texture depending on the substrate bias. The dependence of crystallographic texture of Cr on substrate bias is discussed with a model. 8 It is also well known that when Co alloys are deposited on Cr with the (110) texture
Data Loading...
