Inquiries

Metal ion stabilization in cleaners Fine Chemicals Research Department of Company X, a chemical manufacturer

Prevents metal re-deposition

Additive inspired by plating industry chelating agents

Electronics
Dispersion / Aggregation

Mr. P is involved in the research and development of various cleaning agents at chemical manufacturer X. He received a call from a sales representative saying, "A client who sells semiconductor cleaning agents has asked us to work together to come up with a solution to improve yields."

* This is a hypothetical example posted as a reference for those with similar challenges

Challenges

It is difficult to prevent metal re-adhesion onto substrates during cleaning...

The Fine Chemicals Research Department of chemical manufacturer X conducts research and development of various industrial cleaning agents. The department to which Mr. P belongs is responsible for the research and development of various chemicals used in the semiconductor manufacturing process, such as semiconductor cleaning agents, rinse agents, and etching agents.

Mr. P, a mid-level employee, was involved in formulating semiconductor cleaning agents and evaluating them with cleaning equipment. Looking back on those days, Mr. P says:

"It all started when a sales representative contacted me and said, 'A client has asked us to improve the semiconductor manufacturing yield, and we'd like you to give us some specific advice.'"

"As semiconductors become increasingly miniaturized, it is necessary to effectively remove various cleaning substances from the surface of the devices. The cleaning process is a critical step that determines the yield, so it is necessary to design the cleaning agent formulation by combining various ingredients according to the type of material to be cleaned." (Mr. P)

The challenge this time was, "How can we prevent metal ions that are detached from the substrate and dissolved in the cleaning agent from depositing during cleaning, and thereby obtain highly clean substrate surfaces with good reproducibility?"

It has been found that the re-adhesion of metals onto the substrate can be prevented by stabilizing the metal ions in the cleaning agent.

Mr. P currently uses additives with chelating properties such as EDTA (ethylenediaminetetraacetic acid) and EDTPO (ethylenediaminetetrakis(methylenephosphonic acid)) in his cleaning agents, but these are not able to meet the required level, so he began looking for a new solution.

We have tried combining several additives to stabilize metals in the cleaning agent, but have not been able to get good results. The delivery date requested by our client is approaching...

Key Challenges

  • We were consulted on whether it would be possible to suppress metal re-adhesion during cleaning as a measure to improve semiconductor yields.

  • To prevent metal re-adhesion during cleaning, it was necessary to stabilize the metal ions in the cleaning agent.

  • The required level could not be achieved using chelating additives such as ETDA alone.

Solutions

Solution Summary

  • Succinic acid has been used as a "complexing agent" in plating chemicals to stabilize metal ions.

  • The succinic acid that Nippon Shokubai has been producing for many years is well-known for its quality and stable supply.

  • By adding chelating agents such as EDTA and succinic acid to the cleaning agent and evaluating it, it was found that it may be possible to suppress the deposition of metal ions.

Mr. P, who was researching complexing agents, was told by a veteran employee, "If you're looking to stabilize metal ions in the liquid, we've considered succinic acid when we were developing plating chemicals."

I immediately looked it up on the web, and found information on the Nippon Shokubai website that stated, "Succinic acid is used as a complexing agent in plating chemicals to stabilize metal ions."

Mr. P immediately called the person in charge at Nippon Shokubai to discuss the details.
"The sales representative told me that Nippon Shokubai also produces maleic anhydride, the raw material for succinic acid, and that because they have an integrated production system that starts from the raw material, they have an established reputation for stable quality and supply." (Mr. P)

After ordering a sample of industrial succinic acid and testing it with a number of chelating agents, it became clear that it might be possible to prevent metal re-adhesion. Mr. P felt a little relieved.

While preparing for scale-up, Mr. P is thinking that if the evaluation results are favorable, he would like to propose succinic acid as an alternative to other cleaning agents being considered by the same department.

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