U of M Materials Science Seagate Design Group

1. 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

2. Outline • Project Overview • Possible Solutions • Idea Selection • Detailed Solution

3. Overview Dr. Marcus Mooney, Materials for Electronics, Seagate

4. 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

5. Possible Solutions

6. 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

7. 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 7

8. 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

9. 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 9

10. Idea Selection

11. 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

12. Idea Selection Process • Cost (10%) • Time (20%) • Final Roughness (40%) • Ease of implementation (30%) • Total

13. Detailed Solution

14. 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

15. Process Control Options http://www.icknowledge.com/misc_technology/CMP.pdf

16. 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

17. 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