Devices and methods for measurement of magnetic characteristics of MRAM wafers using magnetoresistive test strips
US9252187B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 3, 2014 |
| Grant date | Feb 2, 2016 |
| Priority date | — |
| Expiry date | Aug 8, 2034 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C2029/5002
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Methods for testing magnetoresistance of test devices with layer stacks, such as MTJs, fabricated on a wafer are described. The test devices can be fabricated along with arrays of similarly structured memory cells on a production wafer to allow in-process testing. The test devices with contact pads at opposite ends of the bottom electrode allow resistance across the bottom electrode to be measured as a surrogate for measuring resistance between the top and bottom electrodes. An MTJ test device according to the invention has a measurable magnetoresistance (MR) between the two contact pads that is a function of the magnetic orientation of the free layer and varies with the length and width of the MTJ strip in each test device. The set of test MTJs can include a selected range of lengths to allow the tunnel magnetoresistance (TMR) and resistance area product (RA) to be estimated or predicted.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.