When copper is annealed some of its molecules want to diffuse into the dielectric; unfortunately, this diffusion reduces the insulation and degrades mechanical and thermal properties. To prevent Cu diffusion, “cap” layers of another metal are placed as a barrier between the copper and polyimide. These metal barriers also enhance the copper-polyimide adhesion.

The YES process uses a 20 angstrom layer of AminoPropylTriEthoxySilane (APTES) as a barrier layer. While a 1,000 angstrom wide copper trench using 200 angstroms for a barrier metal layer wastes 40% of the available copper volume, using 20 angstroms of APTES as a barrier layer only utilizes 4% of the available copper volume. Tests of APTES show increased copper to low-k adhesion without deterioration (up to 450°C).

Because an oxide quickly forms on copper exposure to air, post-CMP cleaning and stripping of the oxide is necessary before the next process step. It’s also essential to remove all copper residues from the surrounding dielectric field to keep residues from acting as troublesome nucleation sites.

Thorough copper oxide removal can be achieved through plasma cleaning, utilizing a product such as the YES-CV200RF or the YES-G1000.

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News & Updates

  • Solutions for Nano and Micro-Structured Optical Films (pdf)
  • Medical Device Industry White Paper (pdf)
  • Genomics White Paper (pdf)
  • October 22-23, 2019 - Visit YES at Booth #39 at the International Wafer Level Packaging Conference at the San Jose Doubletree Hotel
  • October 7-9, 2019 - Visit YES at Booth #8 at Lab On a Chip at the Coronado Island Marriott Resort & Spa (San Diego, CA)
  • July 9-11, 2019 - Visit YES at booth #932 at Semicon West in San Francisco
  • June 25-27, 2019 - Visit YES at booth #244 at Sensors Expo and Conference in San Jose
  • May 28-31, 2019 - Visit YES at booth #219 at ECTC in Las Vegas
  • April 29-May 2, 2019 - Visit YES at booth #306 at CS Mantech in Minneapolis
  • March 4-7, 2019 - Visit YES at Booth #64 at the IMAPS Device Packaging Conference in Arizona

Other Updates


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Located in Livermore, California, Yield Engineering Systems (YES) is a privately held company that manufactures engineering process control equipment to meet the needs of innovative engineers and lab managers.

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