Exam Questions

Max Gage

Committee: Nix, Clemens, Dauskardt

Project: Mechanical Properties of Carbon-Doped Oxide Low-k Thin Films

Research related questions:

CLEMENS:

Define potential energy of a cracked body.

Strain energy minus any work done by external loading system.

Describe equivalence of stress intensity factor and strain energy release rate.

The parameters are simply related by material properties under the assumption of linear elastic fracture mechanics. He was confused because he thought that by “equivalent” I meant that they are equal.

Describe CVD deposition process. Under what conditions would you want to heat the substrate? Under what conditions would you heat the vessel walls? Define enthalpy and Gibbs free energy of a reaction. Define exothermic versus endothermic reaction. Describe what factors affect rate of reaction. In the law of mass action, which factors represent the energy to be overcome and which represent the driving force (in terms of an activated complex)?

I proposed that whether you heat the substrate or the vessel should depend on whether the reaction is exothermic or endothermic. I wasn’t sure exactly what he was driving at with reaction rate. But he seemed happy when I put up the law of mass action and related the reaction rate to an activated complex with a driving force.

Describe all sources of residual stresses that are present in the deposited CDO films. Can you have growth stresses in amorphous materials?

The main components are due to thermal mismatch upon deposition and subsequent cooling. Growth stresses are possible in amorphous films as long as there is sufficient mobility.

Core Courses:

CLEMENS:

Define electrical displacement. How does that relate to polarizability?

I put up the right equations but didn’t know what he wanted for a definition of D. In the end I arrived at the definition in the reverse order.

How does the dielectric constant relate to the index of refraction?...