October 13, 2006 Kyushu Institute of Technology Kyushu Institute of Technology Prof. Keiichi Kimura Keiichi Kimura, Katsuya Nagayama, Yosuke Inatsu, Panart Khajornrungruan Department of Mechanical Information Science and Technlogy, Kyushu Institute of Technology 2006 ICPT A lodestar on pad groove pattern design with slurry flow analysis and visualization experiments in CMP process A lodestar on pad groove pattern design with slurry flow analysis and visualization experiments in CMP process

October 13, 2006 Kyushu Institute of Technology Kyushu Institute of Technology Prof. Keiichi Kimura Outline 1.Introduction 2.Computational analysis method 3.Visualization experiment method 4.Basic slurry flow 5.Slurry flow simulation and visualization experiments 6.Lodestar of groove pattern design 7.Conclusion

October 13, 2006 Kyushu Institute of Technology Kyushu Institute of Technology Prof. Keiichi Kimura Configuration of CMP machine & process Material removal Interaction among 3 factors wafer surface slurry polishing pad Slurry Polishing Pad Silicon Wafer = next

October 13, 2006 Kyushu Institute of Technology Kyushu Institute of Technology Prof. Keiichi Kimura Material removal between wafer and pad surface wafer surface slurry polishing pad Silicon wafer Polishing pad V supply & drainage slurry flow wafer and pad contact physical & chemical contact material, surface asperity chemical & particles material & asperity next polishing conditions polishing speed polishing pressure

October 13, 2006 Kyushu Institute of Technology Kyushu Institute of Technology Prof. Keiichi Kimura   455  200 11 22  polishing pad wafer (a) Concentric groove pattern (b) Radial groove pattern Configuration of CMP model & polishing pad pitch of grooves: 2 mm width of groove : 1 mm width of land: 1 mm depth of groove: 1 mm angle bet. grooves: deg. (32 divisions) width of groove : 1 mm depth of groove: 1 mm next

October 13, 2006 Kyushu Institute of Technology Kyushu Institute of Technology Prof. Keiichi Kimura Pad Edge Wafer Pad center Grooves - Concentric groove Lattices : 1,000,000 - Radial groove Lattices : 600,000 Computational model between wafer and groove pad Heat fluid analysis code : FLUENT Continuity equation - Navier-Stokes equation - Diffusion equation for slurry transportation Groove Gap Height wafer 1 mm Groove cross-section (not in scale) 10  m gap pad groove wafer 1 mm Groove cross-section (not in scale) 10  m gap pad groove next

October 13, 2006 Kyushu Institute of Technology Kyushu Institute of Technology Prof. Keiichi Kimura DI water + fluorescent agent polishing pad quartz glass UV light source video camera fluorescent light - Quartz glass :  200 (Supersil-P30 / ShinEtsu Quartz) - Fluid (Slurry) : DI water - Fluorescent agent : FWP-1 / Karl Deutsch - Ultraviolet light source : High pressure Mercury lamp (SHG-200/Mejiro Precision) - Polishing machine : NANOTECH 450-FODCAb/Nanotech Machines) Experimental set-up for slurry flow visualization next

October 13, 2006 Kyushu Institute of Technology Kyushu Institute of Technology Prof. Keiichi Kimura Equal direction area : smooth flow Opposite direction area : jammed flow Basic slurry flow between wafer and pad 1. Slurry flows in thin space between wafer and polishing pad 2. Slurry flow is affected by the motion of wafer and polishing pad next

October 13, 2006 Kyushu Institute of Technology Kyushu Institute of Technology Prof. Keiichi Kimura Slurry movement on polishing pad slurry supply polishing slurry drainage : (a) Groove pattern on pad surface (b) Groove cross section geometry : (c) Pad surface asperity : (a) Groove pattern on pad surface (b) Groove cross section geometry next Grooves on polishing pad 1. Slurry transportation canal 2. Slurry reservoir

October 13, 2006 Kyushu Institute of Technology Kyushu Institute of Technology Prof. Keiichi Kimura Slurry flow simulation : No-groove pad 1 slurry flows in from right side 2 slurry spreads in area of [A] 3 slurry flows down in left area 4 slurry delays flowing in area [B] - No-groove pad -  1 : 60 min -1,  2 : 60 min -1 - slurry flow at 5  m below wafer 22 11 [A] [B] next

October 13, 2006 Kyushu Institute of Technology Kyushu Institute of Technology Prof. Keiichi Kimura Slurry flow simulation : Concentric groove pad Polishing pad rotation Wafer rotation :  1=60 min -1 :  2=60 min -1 1.Slurry flow in from right side of wafer 2.Slurry spreads around from upper side of wafer followed by rotation of wafer 3.Slurry flow delays at bottom side of wafer due to opposite rotation of wafer and pad 4.Shape of delayed slurry flow area is slightly different from no-groove pad 5.Concentric groove pattern can take in and reserve slurry beneath wafer Slurry flow at 5 mm below wafer simulation next

October 13, 2006 Kyushu Institute of Technology Kyushu Institute of Technology Prof. Keiichi Kimura Slurry flow simulation : Concentric groove pad Polishing pad rotation Wafer rotation :  1=90 min -1 :  2=30 min -1 Slurry flow at 5 mm below wafer 1.Slurry flows is slightly different from the case of  1=  Slurry flowing time over whole wafer is short. 3. Delayed slurry flow area is small. 4. Pad rotation influences slurry flow strongly. simulation next  1 >  2

October 13, 2006 Kyushu Institute of Technology Kyushu Institute of Technology Prof. Keiichi Kimura Slurry flow simulation : Concentric groove pad Polishing pad rotation Wafer rotation :  1=30 min -1 :  2=90 min -1 Slurry flow at 5 mm below wafer simulation next  1 <  2 1.Slurry flows same as the case of  1=  Slurry flowing time over whole wafer is not short. 3. Delayed slurry flow area is large. 4. Influences of wafer rotation for slurry flow is not much.

October 13, 2006 Kyushu Institute of Technology Kyushu Institute of Technology Prof. Keiichi Kimura Slurry flow simulation : Concentric groove pad Polishing pad rotation Wafer rotation :  1=60 min -1 :  2=60 min -1 1.Slurry flow in from right side of wafer 2.Slurry spreads around from upper side of wafer followed by rotation of wafer 3.Slurry flow delays at bottom side of wafer due to opposite rotation of wafer and pad 4.Shape of delayed slurry flow area is slightly different from no-groove pad 5.Concentric groove pattern can take in and reserve slurry beneath wafer Slurry flow at 5 mm below wafer simulation next

October 13, 2006 Kyushu Institute of Technology Kyushu Institute of Technology Prof. Keiichi Kimura Slurry flow experiment : Concentric groove pad Polishing pad rotation Wafer rotation :  1=30 min -1 :  2=30 min -1 visualization experiment 1. Concentric groove pattern can take in and reserve slurry beneath wafer 2. Delayed slurry flow area is existed at the bottom side of wafer next

October 13, 2006 Kyushu Institute of Technology Kyushu Institute of Technology Prof. Keiichi Kimura Slurry flow analysis : Radial groove pad simulation Polishing pad rotation Wafer rotation :  1=60 min -1 :  2=60 min -1 Slurry flow at 5 mm below wafer 1. Radial groove pattern can take in slurry, and spread as sweeping fan shape 2. Slurry drainage is carried out quickly next 3. Radial groove gives great influences for slurry flow.

October 13, 2006 Kyushu Institute of Technology Kyushu Institute of Technology Prof. Keiichi Kimura Slurry flow experiment : Radial groove pad2 visualization experiment Polishing pad rotation Wafer rotation :  1=30 min -1 :  2=30 min -1 next 1. Radial groove pattern can take in slurry, and spread as sweeping fan shape 2. Slurry drainage is carried out quickly 3. Radial groove gives great influences for slurry flow.

October 13, 2006 Kyushu Institute of Technology Kyushu Institute of Technology Prof. Keiichi Kimura += Concentric grooveRadial groove Combined groove Concentric groove pad : good to take in and reserve slurry + Radial groove pad : good to drain slurry quickly next Geometry of combined groove

October 13, 2006 Kyushu Institute of Technology Kyushu Institute of Technology Prof. Keiichi Kimura Slurry flow simulation : Combined groove pad Polishing pad rotation Wafer rotation :  1=60 min -1 :  2=60 min -1 1.Slurry flow on combined groove pad is similar to that of concentric groove pad Slurry flow at 5 mm below wafer simulation next 2. Delayed slurry flow area is disappeared 3. Slurry replacement over whole wafer is completed quickly

October 13, 2006 Kyushu Institute of Technology Kyushu Institute of Technology Prof. Keiichi Kimura next Lodestar of groove pattern design 1.Basic functions of grooves on polishing pad are … (a) to transport slurry beneath wafer (b) to reserve slurry (c) to drain slurry to outside of polishing pad 2. Concentric grooves have functions of (a) and (b). - grooves are closed shape in rotating direction and no open - grooves are closed shape in rotating direction and no open orifice orifice 3. Radial grooves have function (c). - all grooves have open orifice - all grooves have open orifice 4. Combined grooves have functions (a), (b) and (c). - it is important to combine concentric grooves and radial - it is important to combine concentric grooves and radial grooves grooves

October 13, 2006 Kyushu Institute of Technology Kyushu Institute of Technology Prof. Keiichi Kimura 1.Computational analysis and visualization experiments were attempted on slurry flow in CMP polishing pad. next Conclusion 3. Basic function of groove pattern such as concentric groove and radial groove is analyzed with analysis and and radial groove is analyzed with analysis and experiments. experiments. 4. Advantages on combined grove is analyzed. 5. Lodestar for groove pattern design is established. 2. Computational analysis and visualization experiments provided similar phenomena each other. provided similar phenomena each other.

October 13, 2006 Kyushu Institute of Technology Kyushu Institute of Technology Prof. Keiichi Kimura next Acknowledgment We are indebted to Dr. K. Hieda, Dr. K. Kuriyama and JSR corporation for their great support and discussion with us on the research. We express plenty of appreciation to them.