ELECTROLESS PLATING OF GLASS AND SILICON SUBSTRATES THROUGH SURFACE PRETREATMENTS INVOLVING PLASMA-POLYMERIZATION AND GRAFTING PROCESSES

Abstract

Electroless plating of nickel (or copper) was carried out on glass (or silicon) substrates that were previously surface modified by using plasma-polymerization and grafting processes, and then activated by immersion in a simple acidic PdCl₂ solution. Three pretreatments based on the deposition of plasma-polymerized thin films (PACVD process) on O₂ plasma-cleaned substrates were investigated. They include film deposition of (1) amorphous hydrogenated carbon (a-C:H) grown from CH₄, whose surface is subsequently plasma-functionalized in NH₃ or N₂; (2) amorphous hydrogenated carbon nitride (a-CN_x:H) grown from CH₄/NH₃ or CH₄/N₂ mixtures; and (3) amorphous hydrogenated carbon nitride grown from volatile organic precursors (allylamine, acetonitrile).

In the three cases, X-ray photoelectron spectroscopy (XPS) results show that chemisorption of the catalyst occurs on the nitrogen-containing functionalities created by plasma polymerization and grafting and thus that the electroless deposition is possible. Differences were observed depending on the nature and thickness of the plasma-polymerized thin films, as well as on the nature and concentration of the nitrogen-containing functionalities present or grafted at the surface. Practical adhesion of Ni films was investigated using a Scotch® tape test. Ni films up to 3 or 4 μm in thickness were shown to pass this test successfully, i.e., without causing any metal detachment.

Keywords:

• Glass
• Silicon
• Ceramics
• Substrate pretreatment
• Plasma polymerization
• PACVD process
• Plasma grafting
• Palladium chemisorption
• Electroless plating
• Peel test
• Adhesion
• XPS analysis

Notes

Presented in part at the 26th Annual Meeting of The Adhesion Society, Inc., Myrtle Beach, South Carolina, USA, 23–26 February 2003.

The adhesion data are relative to the Ni film maximum thickness, which is obtained without any metal squares removed (cross-hatched tape test: Test Value (TV) = 5). Routes (a), (b), and (c) are relative to schemes given in Figure 4.

The adhesion data are relative to the Ni film maximum thickness, which is obtained without any metal squares removed (cross-hatched tape test: Test Value (TV) = 5).