| AVS 57th International Symposium & Exhibition | |
| Plasma Science and Technology | Tuesday Sessions |
| Session PS1-TuM |
| Session: | Advanced FEOL Etching II |
| Presenter: | J. Pereira, LTM - UMR 5129 CNRS, France |
| Authors: | J. Pereira, LTM - UMR 5129 CNRS, France X. Mellhaoui, LTM - UMR 5129 CNRS, France J. Shin, Crocus Technology, France E. Pargon, LTM - UMR 5129 CNRS, France J. Reid, Crocus Technology, France O. Joubert, LTM - UMR 5129 CNRS, France |
| Correspondent: | Click to Email |
Magnetoresistive Random Access Memories (MRAM) is of great interest since they combine the best characteristics of FLASH, SRAM and DRAM memories: non-volatility, low voltage operation, unlimited read and write endurance, fast read and write operation. One of the key parameters for M-RAM technology development is the etching of the Magnetic Tunnelling Junction (MTJ). Today, one of the main methods used for MRAM patterning is based on a pure sputtering dual Ion Beam Etching (IBE). However, IBE technique shows some technological limitations that increases the difficulty of MRAM device manufacturing. Indeed, it has low throughput and cannot be used to pattern very dense structures because of shadowing effects., The process can lead to magnetic materials redeposition on the pattern sidewalls that can short-circuit the dielectric tunnel junction. In this paper, we propose to develop plasma etching technologies to pattern complex stacks of MRAM devices as an alternative to IBE process, improving the manufacturability of MRAM devices.
The aim of this work is to investigate a full RIE process for the patterning of Thermally Assisted MRAM (TA-MRAM) dots in ICP reactors (Decoupled Plasma Source from AMAT).
We propose to investigate innovative plasma chemistries (without O2, Cl2 to avoid corrosion) to etch the magnetic materials composing the MTJ junction. CO/NH3 plasmas assisted by temperature could be very promising plasma chemistries to form volatile metal-carbonyl etch by products and avoid redeposition on the pattern sidewalls.
Optical Emission spectroscopy and reflectometry is used to monitor the plasma process. The etching profile, critical dimensions (CD) and possible redeposition on sidewalls are analysed using Scanning Electron Microscopy (SEM), and Focused Ion Beam devices (FIB-SEM, FIB-TEM). The nature of non-volatile by-products re-deposition is studied using X-Ray Photoelectron Spectroscopy.