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Department of Electrical and Computer Engineering ECE 637 Frequently Asked Questions |
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Q. |
What is the spacing of the probes on the four-point-probe in the cleanroom? |
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A. |
The probe spacing is 1/16" = 62.5 mils. |
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Q. |
What is the contribution of end pads and corners to the resistance of integrated resistors? |
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A. |
The contribution of the end pads to the resistance depends on their geometry. The values for three geometries of end pads and for square corners are shown in a linked figure. |
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Q. |
What are the manufacturer's specifications for the wafers we are using in lab? |
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2"
diameter, (100), p-type, boron doped Si |
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Q. |
What are the calibration factors for the microscope used do measure the device dimensions in lab? |
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A. |
There are two microscopes in the lithography room that you may do measurements on. The larger one is interfaced to a digital camera and computer which can be used to capture images. For information on calibration of the images click here. There are two ways to use the smaller microscope to measure dimensions. If you used the binocular eyepieces, one of the eyepieces has an eyepiece reticle in it. If you used the upper monocular eyepiece in which you turned a dial to move a marker, and read numbers off the dial, you used the filar micrometer.
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Q. |
Is there a color version of the ECE637 Mask set, with each mask level in a different color? |
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A. |
A drawing of the ECE637 Chrome Mask set first used in Autumn 2005 is available. Each mask level is shown in a different color and a key is included in the figure. Note that the conversion of the drawing to GIF format for posting here introduced some distortion of the drawing. |
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Q. |
Why is my measured oxide capacitance so much lower than I predicted? |
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A. |
One likely reason is series resistance. This is particularly true if the substrate contacts on your wafer are not good ohmic contacts (they had non-linear I vs. V). |
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