Adhesion durability of tantalum BPDA-PDA polyimide interfaces

Abstract

Adhesion durability of dc magnetron sputtered tantalum to in situ radio frequency (rf) plasma treated biphenyl tetracarboxylic acid dianhydride-para phenylene diamine (BPDA-PDA) polyimide films was determined as a function of repeated 400°C thermal exposure cycles and 85 °C/80% temperature!humidity (T/H) exposures. rf plasma treatments in Ar, oxygen and a sequential combination of oxygen followed by Ar were evaluated. Using 90° peel testing, it was found that all the plasma treatments resulted in high peel strengths (greater than 60 g/mm) initially and after high temperature thermal exposures, but structures fabricated with rf oxygen plasma treatment rapidly degraded in peel strength during T / H exposure. It is proposed that this hydrothermal degradation is a result of the instability of the nonstoichiometric tantalum oxide present at the metal/polyimide interface which transforms to stoichiometric Ta205 during the T / H exposure. Supporting evidence for this model is presented based on failure analysis of peeled strips by Auger electron spectroscopy as well as in situ x-ray photoelectron spectroscopy observations of the Ta bonding chemistry to the rf plasma treated polyimide.

Effects of Temperature and Humidity Treatment Conditions on the Interfacial Adhesion Energy between the Electroless-Plated Ni and Polyimide

“…In general, interfacial adhesion between metal thin film and polymer substrate decreases after temperature/ humidity treatment. [9][10][11][12]18,22) In this result, electroless-plated Ni/polyimide system shows steep decrease in peel strength after 168 h temperature/humidity treatment. This means weaker interfacial adhesion strength, and therefore, it can be related to the specific interfacial boundary layer relevant to polyimide surface wet pretreatment, which causes degradation of the polyimide itself by the interfacial reaction with humidity.…”

“…Generally, interfacial delamination during peel test occurs near weak adhesion layers for metal-polymer systems. [9][10][11][12]18,22) The vertical peel cracks from peeling direction with narrow spaces are observed at peeled metal surface when there is strong interface adhesion strength, while wide spaces of peel crack are observed for weak interfacial adhesion strength. In our result, peel crack at the peeled metal surface was not observed because the cohesive failure occurs inside the polyimide near Ni/polyimide interface.…”

“…The other source of the interfacial adhesion decrease is the possibility of polyimide degradation with temperature/ humidity. [9][10][11][12] Next, it is important to maintain good adhesion even after an accelerated reliability test at high temperature and high humidity treatment conditions. The interfacial reliability under harsh humidity conditions is an important requirement in microelectronics applications.…”

Effect of Temperature/Humidity Treatment Conditions on Interfacial Adhesion Energy between Inkjet-Printed Ag and Polyimide

“…The major source of oxidation was proposed to be saturation of moisture through the metal/polyimide interface or through the polyimide. 4,5) Previous reports focused on interface oxidation as a main reason for the interfacial adhesion decrease and subsequent degradation of the polyimide with temperature/humidity. [4][5][6][7] However, they did not try to understand the interfacial adhesion of Ag/polyimide systems at the temperature/humidity treatment conditions used.…”

Comparing the surface activities of compounds using an elemental adsorbate

“…Examples of the behaviour of the surface or interface varying significantly with the processing route abound in the literature [1][2][3][4][5]. However, systematic studies linking the processing defects of the surface of a ceramic or polymer to its physical and chemical behaviour [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] have mostly been restricted to a few specific compositions. There are very few data on cross investigation of different surfaces in the same experimental arrangement.…”