U of M Materials Science Seagate Design Group
Post on 03-Jan-2016
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U of M Materials Science Seagate Design Group
Alan Bagwell
Tony Lindert
Loc Nguyen
Greg Rayner
Industrial Mentor:Dr. Vince Engelkes
Faculty Advisor:Prof. C. Daniel Frisbie
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Outline
• Project Overview
• Possible Solutions
• Idea Selection
• Detailed Solution
Overview
Dr. Marcus Mooney, Materials for Electronics, Seagate
Project Goals
Main Goal:• Reduce transducer RMS roughness from 10 Å to 2 Å
Other Considerations:• Materials should not undergo phase changes up to
250 ºC or react with neighboring materials• Must have a product life of at least 5 years• Ease of production and fabrication• Cost
Possible Solutions
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Solution #1: Chemical Mechanical Planarization/Polishing (CMP)
A process that uses an abrasive, corrosive slurry to physically grind flat and chemically remove the microscopic topographic features on a wafer so that subsequent processes can begin from a flat surface*.
Advantages:• Ease of implementation• Low cost
Disadvantages:• Roughness control
*www.appliedmaterials.com/products/cmp_4.html**http://www.scsolutions.com
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Solution #2: Spin-on Glass (SOG)
A process that uses an liquid form of glass to fill small gaps between metal layers*.
Advantages:• Ease of implementation• Low cost
Disadvantages:• Possible materials contamination• Magnetic and electrical property
*Optimization of Spin-On-Glass Process for Multilevel Metal Interconnects. Aric C. Madayag and Zhiping Zhou. Georgia Institute of Technology
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Solution #3 Focused Ion Beam (FIB)
FIB can be used to mill and polish sample using a focused beam of gallium ions*.
Advantages:• Superior polishing
Disadvantages:• Cost • Time• Redeposit/Contamination
* http://www.fei.com/uploadedFiles/Documents/Content/2006_06_FIBCapabilities_td.pdf
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Solution #4 Materials Change
Changing current materials for reader/writer elements with similar materials with comparable magnetic and modulus properties.
Advantages:• Better polished potential
Disadvantages:• Magnetic and electrical property
Idea Selection
Idea Selection Criteria
• Final Roughness- How well the process will achieve the 2 Å target goal.
• Ease of Implementation- Time and cost to put the process into practice
• Cost- Increase to the current production cost
• Time- Increase to the current production time
40%
30%
10%
20%
3 1 2 4
3 1 4 2
3 4 3 2
4 2 1 3
•Cost (10%)
•Time (20%)
•Final Roughness (40%)
•Ease of implementation (30%)
•Total
Idea Selection Process
CMP FIB Material Change
SOG
3.3 2.5 2.5 2.5
Detailed Solution
Chemical Mechanical Planarization Overview
• Culmination of several smoothing processes
• Key components:– CMP Pad– Slurry– Process control:
speed, pressure, etc.http://www.icknowledge.com/misc_technology/CMP.pdf
Process Control Options
http://www.icknowledge.com/misc_technology/CMP.pdf
Slurry
• Critical to achieving low roughness values• Different slurry options:
– Slurry material choice (chemical interactions)– Solution concentration– Particle size:
http://www.iop.org/EJ/abstract/0953-8984/20/22/225011
Summary
• CMP is the final process currently used in smoothing transducer elements
• CMP is the best solution for our target 2 Å roughness
• Many options for improving CMP – slurry is especially important
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