Adhesion Enhancement of a Plated Copper Layer on an AlN Substrate Using a Chemical Grafting Process at Room Temperature

Nickel dependence of hydrogen generation, hydrogen co-deposition and film stress in an electroless copper process

The scope of electroless copper plating technology is evolving to applications with smaller structures and smoother substrates, where adhesion of the copper film can be hard to achieve. The extent to which different factors, such as film stress and hydrogen evolution, contribute to delamination and blister formation on smooth organic substrates is a topic of active discussion. Stress and strain evolution is reported here for a nickel- and formaldehyde-free formulation for a range of plating bath temperatures. X-ray diffraction, with the sin2 ! method, was used to monitor the strain within the copper crystallites during and after their growth. Substrate bending measurements were used to detect the average stress of the film. This technique indicates a 60 nm wide zone of tensile stress at the interface between substrate and film. During and immediately following deposition, the average substrate stress is more compressive than implied by the strain of the Cu crystallites. After deposition, the additional compressive stress seen by substrate bending relaxes until it matches the Cu crystallite strain. Furthermore, the thermal substrate contraction effect upon termination of plating is considered, since it may influence the film adhesion.

http://jes.ecsdl.org/content/160/6/D226.full.pdf

Stress and Strain Evolution in Electroless Copper Films Evaluated with X-ray Diffraction and Substrate Curvature

There are numerous substrates that are electroplated in electronic industry to use in electronic devices. Nickel–Cobalt (Ni–Co) is one of the substrates that is used in the integrated circuits for ...

A study of defects generation on Ni–Co substrate during electroplating and its minimisation through proper cleaning

The effect of inducing uniform Cu growth on formation of electroless Cu seed layer

Electroless copper (Cu) plating is a key process to provide seed layers for the subsequent Cu electroplating in the printed wiring boards (PWBs). Due to the demand for lower power dissipation at higher temperatures and high signal frequencies, various kinds of organic materials have been newly introduced as substrates. However, they have come with defects such as delamination and/or blisters in the Cu layers on organic substrates, i.e., weak adhesion. Here we demonstrate the root cause and a prevention method of the blister formation. Various parameters affecting the blister formation have been investigated combined with the deposit thickness (internal stress), hydrogen gas evolution, and codeposited Ni content in the electroless Cu plating. It was not obvious that the compressive internal stress in deposits was directly related to the blister formation. Instead, the hydrogen gas evolution clearly turned out to be the key factor, and it was observed that Ni added plating solutions reduced the hydrogen gas evolution significantly and thus produced no blisters in the Cu deposits. The control of blisters would be more critical as the line and space become narrower in the production lines such as ball grid array (BGA) and high density interconnection (HDI).

/pdf/prevention-of-blister-formation-in-electrolessly-deposited-49jmqjpyec.pdf

Prevention of blister formation in electrolessly deposited copper film on organic substrates

Water pollution by ammonium ion and nitrate is a common and growing problem in the ecosystem. Process of biological removal consists of nitrification and denitrification by bacteria. Ammonium is oxidized generally to nitrate by nitrification and nitrate is reduced to dinitrogen gas in the subsequent denitrification process. Although natural zeolite is well known for its ability to preferentially remove ammonium, it is not sufficiently removing ammonium ion and nitrate by adsorption. In order to overcome this problem, a method of biological removal with zeolite is used for simultaneous removal of ammonium and nitrate. As a result, in case of shaking culture with 1% seed and passing through zeolite column, the process revealed that ammonium ion could be removed completely after 14 hours. The removal of nitrate using columns with naturally adsorbed bacteria onto zeolite reached approximately 100% after 4 hours.

/pdf/ceonyeon-zeolitewa-misaengmuleul-iyonghan-nh4-mic-no3-yi-lnibq3u4qh.pdf

Seon-hee Lee

Papers

Prevention of blister formation in electrolessly deposited copper film on organic substrates

천연 zeolite와 미생물을 이용한 NH4+및 NO3-의 동시 제거