CMP Solutions for 10nm and Beyond: Breaking trade-offs in the Planarization / Defect Balance

Transcription

1 SMC Korea May 18, 2016 CMP Solutions for 10nm and Beyond: Breaking trade-offs in the Planarization / Defect Balance Marty W. DeGroot Global R&D Director, CMP Technologies, The Dow Chemical Company

2 Key Challenges for Advanced Node CMP Wafer-scale control in FEOL for FinFET devices Narrow window of operation: tighter lot-to-lot and within lot variation Stringent thickness control requirements: <50 Å / min across wafer Removal rate consistency throughout process lifetime Edge profile control and consistency is critical Reduced topography and defect tolerance Low dishing, high PE is increasingly important Incoming topography < typical CMP capability More CMP at or near the transistor dishing and defects! Emphasis on reduction of micro-scratch count and depth particularly for thinner layers 3D stack designs Requiring high removal rate and excellent control of topography Contact pressure regulation on wafer Break conventional trade-offs in defects and planarization High removal rate, high PE materials CMP materials design needs to accommodate much more stringent demands in feature and wafer scale uniformity SMC Korea May 18, 2016

3 Planarization efficiency: length scales and trade-offs Different phenomena contribute to planarization at different length scales High modulus materials tend to exhibit improved planarization at feature and die scale For die scale planarization, pad stack properties have a larger impact In both cases, planarization / defect trade-off follows the expected trends Key challenge is to develop highly planarizing pads with low defectivity

4 Length scales for feature level planarization Planarization of wafer features relies in part on the nature of the interaction of contacting asperities within pad texture with the device features. Material design for planarization must consider: Material properties of the pad material at the contact interface under prevailing CMP conditions Characteristics of pad texture

5 Understanding pad surface morphology

6 Micro CMP Environment

7 Feature scale planarization critical first step l F =Feature Size ~(20-100) microns 0.8um C l F For each feature, a critical step height ( c ) can be defined as the onset of low area removal c is dependent upon feature size and density, surrounding features and the characteristics of the contacting material

8 Contact pressure Material Differentiation Difference in high area vs. low area removal rate dictates planarization capability of the material at feature scale Generally trends with material hardness Softer pad Standard pad EXP pad 22 C 55 C Materials that exhibit different trends provide insight into key properties driving planarization Hard pad Hard pad Softer pad Standard pad EXP pad Material (hardness) parameter

9 Normalized scratch defects Normalized scratch defects Planarization Efficiency Development of high PE / low defect materials Multi-parametric optimization required to optimize planarization capability within a given material space Governed by materials mechanics and texture morphology Custom Texture Parameter Understanding material properties under CMP relevant conditions provides an avenue to reduce defects for highly planarizing materials High PE materials High PE materials Bulk material parameter A in situ material parameter B

10 High planarization / low defect pads Silica slurry Hard pad EXP pad Ceria slurry Hard pad Soft pad EXP pad

11 Long range planarization Novel 3D architectures accentuate challenges in long range planarization Doming Material mechanics / asperity level dominates feature scale planarization Product level mechanistic design can be used to improve long length planarization

12 Conclusions New device integration schemes introduce new challenges for CMP process tolerances Typical planarization / defectivity balance insufficient to meet process requirements for critical layers Mechanistic understanding of pad / wafer interactions during CMP is essential to intelligent material and product design Fundamental understanding of material response under prevailing CMP conditions enables new parameters that can be independently tuned to break planarization and defectivity trade-offs Pad materials with planarization equivalent to hard pad materials and defectivity comparable to soft pad materials have been developed Long range planarization requires optimization of mechanical properties at product scale vs. asperity scale.