CMP Users Meeting. Impact of CMP buffing chemistry on defects level for interconnections on CMOS processing. April 12 th 2013 D.

Size: px

Start display at page:

Download "CMP Users Meeting. Impact of CMP buffing chemistry on defects level for interconnections on CMOS processing. April 12 th 2013 D."

Logan Robbins
6 years ago
Views:

1 Impact of CMP buffing chemistry on defects level for interconnections on CMOS processing CMP Users Meeting April 12 th 2013 D.JEANJEAN Damien JEANJEAN Olivier ROBIN Sebastien GAILLARD David GALPIN Grégoire DUCOTEY Frédérique TRENTESEAUX Olivier HINSINGER STMicroelectronics, Crolles France

2 Outline 2 Motivation of the study introduction Chemistry introduction results Defectivity, D0 electrical data Discussion on defects removing mechanism Conclusions

reductions induce new technological challenges Introduction of new interconnect

3 Context : IC manufacturing 120 nm 90 nm 65 nm 45 nm 32/28 nm IC evolution is driven by Cost reduction Complexity Performances Miniaturization Dimension reductions induce new technological challenges Introduction of new interconnect materials have driven the development of new CMP and post- CMP cleaning applications. 3

4 Context : CMP related defects Among CMP defectivity catalogue Slurry balls are potentially serious killer defects Why? Silica balls used as abrasive in commercially available slurries Ø from 25nm to 120 nm with different solid content % Size to be compared to the lines width of latest technologies nodes ITRS Roadmap 45 nm node M1/MX pitch 130/140nm 32nm node M1/Mx pitch 90/100nm 22 nm node M1/Mx pitch 60/70nm Silica balls can be left post CMP process: how it impacts the lots processing? 4

Slurry balls defect density Motivation of the buffing

Defectivity review done post CMP Cu line 1 & post hard

generate topography on subsequent dielectrics inducing

X-section Trend Slurry balls at HML2 With excursions

solution and benchmark with other chemistry in brushes

5 Slurry balls defect density Motivation of the buffing step introduction 5 In line defects characterization Defectivity review done post CMP Cu line 1 & post hard mask etch line 2 Silica slurry residues let by CMP generate topography on subsequent dielectrics inducing mispatterning CMP Cu Line1 Hard mask etch line 2 TEM X-section Trend Slurry balls at HML2 With excursions Defects could generate shorts and metals opens cleaning solution and benchmark with other chemistry in brushes not enough efficient Need to adress this defectivty Platen 3 buffing Step introduction

Experiments description AMAT Reflexion LK Diel Cu Platen 3: Barrier CMP Cleaner Low pressure Platen 3 buffing DIW is compared to alcalin chemistry

6 Experiments description AMAT Reflexion LK Diel Cu Platen 3: Barrier CMP Cleaner Low pressure Platen 3 buffing DIW is compared to alcalin chemistry dispense + acidic chemistry in cleaner is kept The experiment sequence is Over rinse in brush box1 beginning Chemistries Slurry Cleaner ph Alkaline Alkaline Acidic

defectivity results on lots 7 Post CMP def inspection

reduction of corrosion defect type No change on other defects

B Balls are form previous level embedded Buffing step A) Split

7 Slurry balls defects count A.U Slurry balls defect count AU Corrosion defect count AU Major defectivity results on lots 7 Post CMP def inspection Defectivity trend after buffing step introduction Huge reduction of corrosion defect type No change on other defects types Buffing step Post etch hard mask line2 def inspection A B Balls are form previous level embedded Buffing step A) Split lot analysis Slurry balls defects density / 10 vs B) Defectivity trend after buff introduction Gain confirmed

D0 Opens M2 D0 Short M2 Majors Yield D0 electric

) x -38% M2 Opens vs M1 split Metal 2 Opens: Split

8 D0 Opens M2 D0 Short M2 Majors Yield D0 electric results 8 M2 Shorts vs M1 split Metal 2 Shorts: Split lot analysis allows to reduce Metal shorts vs M2 shorts vs M1 split D0 (a.u.) x -38% M2 Opens vs M1 split Metal 2 Opens: Split lot analysis allows to reduce Metal Opens vs M2 opens vs M1 split D0 (a.u.) x -23%

9 Discussion - Slurry particles removal in 2 steps 9 Silica particles deposit Post CMP process, 2 cases: Embedded in Cu-BTA positively charged Free balls on both surfaces Dielectric Cu Ta Stage 1: silica particles removing : P3 buffing with alkaline chemistry Allowing strong surface repulsion from dieletrics Due to strong negative Zeta potential P3 Alcalin Chemistry Dielectrics Silica balls Zeta Potential values ~ -80mV ~ -55mV Weaker effect on Cu-BTA removing Dielectric Cu Ta Stage 2: silica particles removing : brush cleaning with acidic chemistry Allowing to remove faster Cu-BTA residues And the Embedded silica particles Avoid redeposition Weaker effect on free slurry balls Dielectric Cu Ta

10 New CMP buffing chemistry has been introduced on platen 3 Summary 10 The chemistry sequence is then alcalin chemistry on p3 following by acidic chemistry in cleaner Allowing the removing of free slurry balls let on wafers and clusters balls embedded in Cu-BTA residues A longer life brush can be expected A reduction of defects type as corrosion and slurry balls has been mesured on lots monitoring the line Opens and Shorts D0 level reduction has been measured. Buffing P3 impact and results is slurry dependant: Next: Solid abrasive size and BTA content to be carefull in the choice of next technology nodes slurries

11 Thanks for your attention 11 Presentation Title

SLURRY FORMULATION OPTIONS

SLURRY FORMULATION OPTIONS CHALLENGES FOR DEFECT REDUCTION IN CU,Ta/TaN AND Ru PLANARIZATION S. V. Babu Center for Advanced Materials Processing, 1 Clarkson University (www.clarkson.edu/camp) Acknowledgments