Dismiss
InnovationQ/InnovationQ Plus content will be updated on Sunday, June 25, 10am ET, with new patent and non-patent literature collections. Click here to learn more.
Browse Prior Art Database

Method for Fabricating Magnetic Multilayers

IP.com Disclosure Number: IPCOM000007641D
Original Publication Date: 2002-Apr-10
Included in the Prior Art Database: 2002-Apr-10
Document File: 6 page(s) / 71K

Publishing Venue

Motorola

Related People

Jamie Schaeffer: AUTHOR [+3]

Related Documents

U.S. Patent No. 6,139,700: PATENT [+10]

Abstract

A method for fabricating magnetic multilayers as required for high-aspect ratio cladding structures and novel giant magnetoresistance (GMR) heterostructures for use in Magnetic Random Access Memories (MRAM) is described. Cladding structures, which are formed on three sides of a Cu line in the back-end of typical IC processing, present trench fill and step coverage issues that threaten the extendibility of MRAM technologies. In GMR multilayer devices, thickness non-uniformity of the individual layers and rough interfaces tend to degrade the coupling between ferromagnetic layers resulting in a poorly defined high-resistance state and degraded device performance. An atomic layer deposition (ALD) process that achieves conformal side wall depositions with the desired film composition for the barrier/cladding/barrier stack as well as atomically sharp interfaces in GMR multilayers with precision control of layer thickness is described. A method of obtaining the desired NiFe alloy composition using ALD is described. Furthermore, a GMR multilayer structure with all layers consisting of bimetal alloys or oxide materials is described.

This text was extracted from a Microsoft Word document.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 25% of the total text.

Method for Fabricating Magnetic Multilayers

Jamie Schaeffer, Rajesh A. Rao and Bich-Yen Nguyen

A method for fabricating magnetic multilayers as required for high-aspect ratio cladding structures and novel giant magnetoresistance (GMR) heterostructures for use in Magnetic Random Access Memories (MRAM) is described.  Cladding structures, which are formed on three sides of a Cu line in the back-end of typical IC processing, present trench fill and step coverage issues that threaten the extendibility of MRAM technologies.  In GMR multilayer devices, thickness non-uniformity of the individual layers and rough interfaces tend to degrade the coupling between ferromagnetic layers resulting in a poorly defined high-resistance state and degraded device performance.  An atomic layer deposition (ALD) process that achieves conformal side wall depositions with the desired film composition for the barrier/cladding/barrier stack as well as atomically sharp interfaces in GMR multilayers with precision control of layer thickness is described.  A method of obtaining the desired NiFe alloy composition using ALD is described.  Furthermore, a GMR multilayer structure with all layers consisting of bimetal alloys or oxide materials is described.

Magnetic Random Access Memories (MRAM) technologies involve a magnetic bit, usually a magnetic tunnel junction (MTJ) or a GMR multilayer structure and a cladding module, which focuses the applied magnetic field onto the bit and also provides shielding from extraneous magnetic fields.  The material and process requirements for both the cladding module as well as the magnetic bit are quite stringent.  For instance, the cladding module requires the sequential deposition of a Tantalum based barrier layer, a NiFe alloy cladding layer, and a second Tantalum based barrier layer in a high aspect ratio trench structure (see figure 1).  This structure is similar to the copper interconnect structures with a single tantalum barrier layer that is found in typical integrated circuit manufacturing.  Achieving conformal tantalum step coverage, and void free fill with the subsequent copper seed and fill depositions, is a difficult task even when only one barrier layer is being used. To improve the barrier layer conformality, new deposition techniques have been.  Most recently, IMP deposition has been used for the tantalum based barrier layer depositions, but other techniques such as chemical vapor deposition and atomic layer deposition will be required for future process technologies.  Satisfying the step coverage demands for the digit and bit lines on MRAM technologies is even more difficult due to the addition of a cladding layer and a second barrier layer that narrows the effective trench width.  Yield impacting voids in the interconnect structure may result from poor trench filling. 

Giant Magneto-Resistance (GMR) devices consist of stacks of alternating ferromagnetic and non-magnetic conductor layers, each ~ 10-80A thick.  These multilayer stacks exh...