Midterm Examination

This midterm examination comprises of two parts:

Part I is a set of questions that must be completed within a period of 45 minutes. It is open book, open notes, but you must not discuss or collaborate on the solution with anybody in the class or outside the class.

Part II is a design problem for making  a sensor described in one of the references below. You MUST collaborate in groups of two or three students. A presentation of your project will be given in class at the allocated times.

Part I (50%)

Questions carry equal points.

Question 1: (Oxidation)

A 100 nm gate oxide is required for some technology. It has been decided that the oxidation will be carried at 1000^o C in dry oxygen. If there is no initial oxide on the surface of the silicon wafer, for how long should the oxidation be done? Is the oxidation in the linear regime, parabolic or in between the two?

Question 2: (Photolithography and Patterning)

Draw a sequence of process steps for the sensor project that you did in the lab. Briefly describe each one of them.

Part II  (50%)

One application for the microfabricated electrode structures that you have finished in your lab work, is as specific sensors of some chemical substance by coating the electrode area with materials that have some specific  response. Examples are  given in the references 6-12. These papers are more than 10 years old. More recent  work that employs similar structures in a sensor applications can be found in journals such as:  "Sensor and Actuators".

1) Do a critical review for ONE of the papers above. Contrast the work in the paper with more recent work. (read and cite at least ONE and no more than FIVE articles in the last three years that are related to the original paper).

2) Design the process flow for fabricating the sensor of your choice -preferably one that you have reviewed-. Begin with the semi-finished wafers that we processed  in the lab and add processing steps to the existing structures. Give steps, temperatures, times, solutions and provide a  list of materials  required for the design.

3) Design an experimental procedure and protocol to characterize your sensor. Give details of the instruments -home build or commercial-.

4) Do the lab work if  you have time and present the experimental results!