University of Limerick EE6641 Semiconductor Technology , Autumn 2009 by umsymums38


									University of Limerick: EE6641 Semiconductor Technology, Autumn 2009. T. Cummins.

Seven Homework Questions (12 marks).          Answers to be returned on Mon Nov 23rd 2009.

1.    A silicon wafer has substrate doping of 1015 boron atoms per cm3 . It receives a Phosporus ion-
      implant dose of 7.5 x 1013 ions/cm2 at an implant energy of 200KeV. Calculate the peak
      concentration, and the resulting junction depth.

2.    Consider wet oxidation of a bare (100) wafer (i.e. assume no initial oxide). Estimate the oxide
      thickness for oxidation times of 10 mins, 30 mins, and 1 hour. For the 1 hour case, calculate the
      thickness using the Deal-Grove equation and coefficients.

3.    Pick a typical CMOS process, and using its physical parameters, show how you would calculate the
      Threshold Voltage of an N-channel MOS transistor with 2V of back-bias

4.    A Sept 2009 listing of almost 400 worldwide currently available semiconductor processes is given
      on .
      Collapse this listing into a single-page spreadsheet of vendor versus features. i.e. Vendors in row
      headings, and column headings for Wafer Diameter, Technology Node, No Poly layers, No. Metal
      layers, metal type, and a “Comment” column with any interesting process notes or capability.

5.    1 volt is applied across a piece of pure silicon 100um long with a cross-sectional area of 1um2.
      Calculate the resulting current flow at room temperature, and at 1250C.

6.    The link contains a “reverse engineered”
      analysis of the Analog Devices ADSP21062 DSP processor.
       (a) What semiconductor process technology is used to fabricate the chip?
       (b) What is the gate-oxide thickness?
       (c) Sketch the LOCOS ‘birds-beak’, give it’s dimensions, and explain why it is present.

7.    On the chart “Production Sweet-Spot” (below), fill in your estimates for the year 2009, i.e. where
      you think the “production sweet spots” are for various product categories listed (MPU, DRAM, mix-
      ed signal, etc). Support your answer with references, vendor names, product announcements, etc.

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