Reading Assignment:  Campbell Chapters 10, 12, and 13.

Gas kinetics

1. Giancoli 3^rd edition - question 18.10

To the right is a plot of the number of molecules with a given speed, as calculated by the Maxwell-Boltzmann Distribution.  Explain why the peak of the curve for 310K is not as high as for 273K.  (Assume the total number of molecules is the same for both.)

2. The average distance from a sputtering target to the wafer is about 5cm. Calculate the maximum pressure in the chamber for a 200°C gold atom to have a mean free path long enough to make it to the wafer.

3. Campbell Chapter 10 - number 6

For a certain process to be successful, it must be run at a chamber pressure of 1 torr, with a gas flow of 1 standard liter per minute.  Find the pumping speed necessary (in liters per minute) to do this if

a) The pump is directly attached to the chamber

b) The pump is attached with a pipe that is 2cm in diameter and 100cm long.

Vacuum Pumps

4. What are the three functions of the fluid in a rotary vane or piston pump?

5. A fifteen stage turbo molecular pump, with a blade tip velocity of 500 m/sec, has a compression ratio for N₂ at 25^oC of 7.7 x 10⁸.  What is the compression ratio for this pump when it is pumping hydrogen (H₂)?

6. When is the best time to use a titanium sublimation pump?  (At what pressure? For what purpose?)

Deposition

7. Campbell Chapter 12 number 2

The evaporator described in Example 12.2 is used to deposit nickel, which has a density of 8.9 gm/cm3 (8900kg/m3).  If the crucible temperature is 1600°C, what is the deposition rate in Å/min?

8. Campbell Chapter 12 number 4

See the book because there's an image involved.

Etching/Lithography

1. Draw a step by step schematic of the fabrication process used to make the features shown below. All green parts are aluminum; some is darker to show depth.  Assume we use a positive photoresist, chemical etching of Si and sputter thin film deposition of Al to make the features. (Hint: We need two mask layers.)

Assignment Readings -

https://www.dropbox.com/s/6z9vhonc2j6biqr/Assignment%20Files.rar?dl=0