AVS 51st International Symposium
    Electronic Materials and Processing Monday Sessions
       Session EM-MoP

Paper EM-MoP7
Inductively Coupled Plasma Etching of Nano-Sized Magnetic Tunnel Junction Stack for MRAM Fabrication

Monday, November 15, 2004, 5:00 pm, Room Exhibit Hall B

Session: Poster Session
Presenter: S.W. Hwang, Samsung Advanced Institute of Technology, South Korea
Authors: S.W. Hwang, Samsung Advanced Institute of Technology, South Korea
S.J. Jung, Samsung Advanced Institute of Technology, South Korea
T.W. Kim, Samsung Advanced Institute of Technology, South Korea
D.J. Ma, Samsung Advanced Institute of Technology, South Korea
Correspondent: Click to Email
There is a strong interest in the development of plasma etching processes for magnetic multilayer structures of the type used in sensores, magnetic random access memories(MRAM). MRAM offers high storage density, fast access time, and infinite rewrite capability. Therefore, there is trend towards nano-size to increase bit storage density. The method for patterning the magnetic tunnel junction(MTJ) stacks that comprise the MRAM is ion milling, which has problems such as sidewall redeposition, etc. In conventional reactive ion etching, the MTJ stack do not form sufficiently volatile etch products to allow efficient pattern transfer. One alternative would be to increase the substrate temperature during etch process in order to increase the vapor pressure of the etch products. This method is not a good option, because of the limited thermal stability of MTJ stacks. In this study, magnetic tunnel junction(MTJ) stacks on Si/SiO@sub2@ were etched using inductively coupled Cl@sub2@-based plasma and the effects of Cl@sub2@-based gas mixtures on the formation of reactive byproducts affecting on MTJ stack etching were investigated. When Cl@sub2@-based gas mixtures were used with Ar or O@sub2@, due to very low vapor pressure of the etch products, thick etch products remaining on the etched MTJ stack could be observed. However, these etch products were easily removed during the etching, especially when BCl@sub3@, C@sub2@F@sub6@ were added to Cl@sub2@/Ar. These results are interpreted as the formations of more reactive products when BCl@sub3@, and C@sub2@F@sub6@ were added to Cl@sub2@/Ar. Therefore, the physical and chemical properties of the etch products formed by the specific gas mixture appear to be important in nano-sized etching of MTJ cell stacks.