Method for Forming a Contact Layer having Strong Adhesion and Exceptional Uniformity on Semiconductor or Thermoelectric Substrate

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Metal deposition using seed layers
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Inventors
Professor Gang Chen
Department of Mechanical Engineering, MIT
External Link (web.mit.edu)
Hsien-Ping Feng
Department of Mechanical Engineering, MIT
Bo Yu
Department of Physics, Boston College
Zhifeng Ren
Department of Physics, Boston College
Shuo Chen
Department of Mechanical Engineering, MIT
Bed Poudel
GMZ Energy, Inc.
Managed By
Christopher Noble
MIT Technology Licensing Officer - Clean and Renewable Energy
Patent Protection

Metal Deposition Using Seed layers

US Patent 8,580,100
Publications
Reliable contact fabrication on nanostructured Bi2Te3-based thermoelectric materials
Physical Chemistry Chemical Physics, 2013,15, 6757-6762

Applications

Fabrication of thermoelectric devices require metallization on semiconductor substrates. This new method of electroplating is applicable in the manufacturing of various substrates and various micro/nano-structures in solar cell, circuit, and optoelectronic technologies. 

Problem Addressed

Electroplating is used in a wide variety of applications due to its inherently low cost for micro and nano fabrication processes. In general, a good electrical and thermal contact is highly correlated to uniform metallizaion on substrates with strong adhesion and an intact interface. However, a smooth or hydrophobic semiconductor surface has low surface energy and poor wettability, leading to a relatively high excess energy for electroplating, which can ultimately cause the film to spontaneously peel off. This invention proposes a method to overcome the difficulties of electroplating on low surface energy substrates by using a seed layer that strongly adheres to the substrate, ultimately improving the electrical and thermal conductivity at low cost and higher throughput. 

Technology

This invention is a thin nanoparticle layer or self-assembled monolayer deposited onto a semiconductor or thermoelectric substrate for electroplating an electrically conducting material with strong adhesion and exceptional uniformity by immobilizing nanoparticles or self-assembled silane monolayers. The invention uses a seed layer that strongly adheres to the substrate to serve as nucleation sites. Metals can only be selectively deposited onto the predetermined seeded regions, thus opening new routes for selective area deposition. Electroplating is then used to grow the metal layer on the substrate, and does not require chemical or mechanical polishing afterward. 

Advantages

  • Improved electrical and thermal conductivity
  • Low cost
  • High throughput
  • Versatile