Study of the High Rate Chemical Mechanical Polishing of Heavily Boron-doped Polysilicon for 3D Applications

• Author / Creator

  Pirayesh, Hamidreza

• The chemical mechanical polishing of polysilicon is a complex process and is not well understood. Despite this, it is used in the semiconductor industry for applications such as via filling and 3D packaging. Although the doping of polysilicon enables applying a wide range of conductivities, boron-doped polysilicon has shown a poor polish removal rates. This is mainly due to role of boron ions in limiting the chemical agent transportation to the surface. Some applications require the removal of more than 10 m of B-doped polysilicon and improvement in the polish rate would reduce the fabrication costs and significantly improve throughput. In this study, it is shown that the adverse effects of boron on polysilicon polishing rate can be minimized by increasing the mechanical interactions during CMP. This was achieved by control of the lubrication behavior during polishing. In addition, enhancement of the process methodology and slurry properties led to an increase of up to 100% in polish rate compared to standard boron-doped polysilicon polish methods. The increase in polish rate did not show any significant wafer surface defect inducing damage.

• Subjects / Keywords

  • Boron doped polysilicon
  • Chemical mechanical polishing
  • Lubrication

• Graduation date

  Fall 2014

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3ZP3W76C

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.