Safety in ‘III/V processing’

Dear all,

In the following text I will give a little explanation about my masterthesis

The title of my masterthesis is ‘Safety issues of III/V processing in microchip manufacturing’. I do this in cooperation with Imec which is situated in Heverlee, Belgium.
My primary supervisor is the head of security of Imec , and actually I work for him. I also stay in close contact with the engineers and a group of scientists that work on this project.

The project didn’t started a long time ago so the work I am going to do can be very crucial for the development of those safety issues which makes it much more interesting for me and it is a bigger challenge because it’s a starting branch of a big and successful company.

In a first stage I have to understand how a microchip is fabricated and how it works. All the steps have to be clear. I also have to understand the techniques that are used to fabricate a microchip.
After this step I had to give a presentation at Imec in front of the head of security and it went great.
Now I am walking in to the second phase which is the understanding of all the chemical reactions of III/V processing and the safety hazards that come with them.
After this brief introduction I am going to discuss the biggest difference between the normal way of fabricating a microchip and III/V processing.

In normal IC development the different layers of the microchip are put on each other. For example we start with a p-doped Silicium (IV) substrate and we start to put other materials on top of this to for example form a pn- and np-junction or to protect the layer beneath (this is done by SiN, TiSi2)… After almost every step that a new layer is composed there has to be an ‘etching-‘or ‘masking’-step. In these steps a part of the layer is removed to form a connection hole or to be filled up with another material. These etching steps are crucial and critical steps because they are often performed by a chemical reaction. Due to this chemical reaction gasses can be formed that can give safety hazards.

In III/V processing the microchip is formed out of components of the third and fifth column of the table of Mendeljev. The base of the microchip is already formed. We don’t work from top to bottom by putting layers on top of each other. A question that may rise is: How do you form the connection holes? And how can the microchip are provided of the necessary material? This is done by penetrating the microchip from the top to the desired layer. This is again done by different etching steps. These etching steps are different from those used in the normal IC manufacturing.

My key purpose is to discover the chemical reaction that occur in these etch-steps and try to find alternatives of solutions to ensure the safety of the employees at Imec. The final goal is to elaborate a risk-analysis. This is not only done by me but in cooperation with the head of security and the engineers.

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2 thoughts on “Safety in ‘III/V processing’

  1. deckersbram says:

    Hi, I’ve made a personal category for your posts, hope you are ok with that? If it has the wrong title or if you want to change anything you can edit it in the dashboard or let me know and I will try to change it for you.

    To comment on your blog, I was wondering what kind of safety hazards rise in the process you are analyzing. Are there toxic fumes produced in the process, is there more a risk for skin irritation when contact is made or is it more a possible explosive reaction if things go out of control or …?

    And secondly, is it your goal to find alternative chemical reactions to achieve the same goal but without using the dangerous substances? Or are you going to devise a list of safety measurements that the employees should follow when they are working on the process, like protective clothing, …?

    • gabuglio says:

      Thank you Bram, I am still not very confidentional with the whole system.

      There are different kinds of safety hazards in the process.
      There are those who you can’t see. These are toxic gases that are a reaction product of the chemical reactions that occur. These gases can be toxic. Some examples are arsine (AsH3), phosphine (PH3) and diborane (B2H6). Gases can also be flammable, these can ignite is they are exposed to sparks of flames. Some examples are H2, PH3. The more hazardous type of flammable gases are the pyrophoric gases, these are gases that ignite spontaneously in air at 54°C or below. Some examples are polysilicon, which is often used in IC manufacturing, Si3N4.
      During chemical reaction there are also liquids as reaction product. There are corrosive chemicals, these can give serious irritation to the skin and eyes. Good protection of the skin and eyes is necessary when working with these chemicals. Solvents are an other type of hazardous liquids. These are often flammable.
      An other risk is radiation, the most dangerous radiation that you can encounter are the X-rays. As a safety measurement the operators wear x-ray monitorbadges and are also often tested for blood-hemoglobine efficiency. This an early indicator for radiation exposure.

      The purpose of my work is to analyze all the reactions and the reaction products and to make the company aware of what types of risk the operators are exposed to. With this information the workconditions will be adjusted to the risks.
      An example is protective clothing. But als the aeration of the building, the way the operators have to handel the machines, …

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