Method of magnetic tunneling layer processes for spin-transfer torque MRAM
US8133745B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 17, 2007 |
| Grant date | Mar 13, 2012 |
| Priority date | — |
| Expiry date | Jan 24, 2028 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10B61/22
- WIPO fieldMicro-structural and nano-technology
- WIPO sectorChemistry
Abstract
A method for forming a MTJ in a STT-MRAM is disclosed in which the easy-axis CD is determined independently of the hard-axis CD. One approach involves two photolithography steps and two etch steps to form a post in a hard mask which is transferred through a MTJ stack of layers by a third etch process. Optionally, the third etch may stop on the tunnel barrier or in the free layer. A second embodiment involves forming a first parallel line pattern on a hard mask layer and transferring the line pattern through the MTJ stack with a first etch step. A planar insulation layer is formed adjacent to the sidewalls in the line pattern and then a second parallel line pattern is formed which is transferred by a second etch through the MTJ stack to form a post pattern. Etch end point may be controlled independently for hard-axis and easy-axis dimensions.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.