Colloidal Silica based High Selectivity Shallow Trench Isolation (STI) Chemical Mechanical Polishing (CMP) Slurry

2005 ◽  
Vol 867 ◽  
Author(s):  
Kyoung-Ho Bu ◽  
Brij M. Moudgil
Keyword(s):  
Silicon Nitride ◽  
Chemical Mechanical Polishing ◽  
Colloidal Silica ◽  
Sodium Dodecyl ◽  
Mechanical Polishing ◽  
Wafer Surface ◽  
Shallow Trench Isolation ◽  
Pattern Size ◽  
Trench Isolation ◽  
Silica Slurry

AbstractAmong various properties of chemical mechanical polishing (CMP) slurry, selectivity plays a key role in global planarization of high density and small pattern size shallow trench isolation (STI) process. Lack of adequate selectivity can lead to defects such as dishing and erosion. To improve the selectivity of STI CMP process, CMP characteristics of silica and silicon nitride wafer were investigated using colloidal silica slurry as a function of slurry pH. Sodium dodecyl sulfate (SDS), an anionic surfactant, was added to increase the selectivity of the slurry. As a result, selectivity increased from 3 to 25. It was concluded that selective passivation layer formed on silicon nitride wafer surface at acidic slurry pH range was responsible for the observed selectivity increase. Adsorption characteristics of SDS on silica and silicon nitride were measured as a function of slurry pH and concentration of SDS. As indicated by zeta potential behavior under acidic pH conditions, SDS adsorption on silicon nitride was significantly higher han silica due to the electrostatic forces. Significantly higher SDS coating on silicone nitride seems to have resulted in lubrication layer leading to increased polishing selectivity.

Effect of Process Parameters on Material Removal Rate in Chemical Mechanical Polishing of 6H-SiC(0001)

2008 ◽  
Vol 600-603 ◽  
pp. 831-834 ◽  
Author(s):  
Joon Ho An ◽  
Gi Sub Lee ◽  
Won Jae Lee ◽  
Byoung Chul Shin ◽  
Jung Doo Seo ◽  
...  
Keyword(s):  
Material Removal Rate ◽  
Chemical Mechanical Polishing ◽  
Material Removal ◽  
Colloidal Silica ◽  
Removal Rate ◽  
Mechanical Polishing ◽  
Diamond Particles ◽  
Average Grain Size ◽  
Silica Slurry ◽  
Sic Wafer

2inch 6H-SiC (0001) wafers were sliced from the ingot grown by a conventional physical vapor transport (PVT) method using an abrasive multi-wire saw. While sliced SiC wafers lapped by a slurry with 1~9㎛ diamond particles had a mean height (Ra) value of 40nm, wafers after the final mechanical polishing using the slurry of 0.1㎛ diamond particles exhibited Ra of 4Å. In this study, we focused on investigation into the effect of the slurry type of chemical mechanical polishing (CMP) on the material removal rate of SiC materials and the change in surface roughness by adding abrasives and oxidizer to conventional KOH-based colloidal silica slurry. The nano-sized diamond slurry (average grain size of 25nm) added in KOH-based colloidal silica slurry resulted in a material removal rate (MRR) of 0.07mg/hr and the Ra of 1.811Å. The addition of oxidizer (NaOCl) in the nano-size diamond and KOH based colloidal silica slurry was proven to improve the CMP characteristics for SiC wafer, having a MRR of 0.3mg/hr and Ra of 1.087Å.

Cerium Oxide Abrasives – Observations and Analysis

2004 ◽  
Vol 816 ◽  
Author(s):  
David R. Evans
Keyword(s):  
Cerium Oxide ◽  
Chemical Mechanical Polishing ◽  
Colloidal Silica ◽  
Silicon Oxide ◽  
Shallow Trench Isolation ◽  
Slow Start ◽  
Process Characteristics ◽  
Detailed Surface ◽  
Trench Isolation ◽  
Conventional Behavior

AbstractThe use of cerium oxide (ceria) as an abrasive for dielectric chemical mechanical polishing has a “checkered” history to say the least. Nevertheless, its use remains attractive for this purpose because of favorable polishing characteristics that are generally not obtainable using conventional fumed or colloidal silica abrasives. To be specific, large differences are commonly observed between removal rates of thin film silicon oxide, silicon nitride, and/or polysilicon. Moreover, such rate selectivity invariably favors removal of oxide films, which of course, is precisely what is desirable for fabrication of modern shallow trench isolation schemes. Even so, CMP using ceria abrasive often exhibits unusual characteristics that cannot be explained adequately by conventional polishing models based on pad/asperity elasticity or pressure distribution over features. Most notably, non-conventional, observed behaviors can be collected under the rubric of “slow start phenomena”. In this work, it is asserted that specific polishing characteristics of ceria slurry are largely due to the detailed surface chemistry of ceria particles and their interaction with silica. In any case, it is further shown that modification of slurry lubrication can alleviate slow-start and shift CMP process characteristics back toward more conventional behavior.

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