We are often asked to recommend books on semiconductor fabrication or semiconductor yield management. Here are some which we found useful:
A good undergraduate introduction to semiconductor fabrication techniques is Introduction to Microelectronic Fabrication by Richard Jaeger. You should also consider the more recent Microchip Fabrication: A Practical Guide to Semiconductor Processing by Peter Van Zant. This is a math-free book. (But note that this edition is unfortunately marred by a fair number of typographical errors.)
A more comprehensive treatment of current technology aimed at a professional audience (and priced accordingly) can be found in the Handbook of Semiconductor Manufacturing Technology edited by Yoshio Nishi and Robert Doering.
A short introductory text on yield prediction is Introduction to Semiconductor Device Yield Modelling by Albert V. Ferris-Prabhu.
A comprehensive treatment of the kind of contingency tables that Q-YIELD produces and theories behind them can be found in Construction and Assessment of Classification Rules by David J. Hand. A statistician's book.
The basic statistics necessary for understanding test results and the significance of yield measurements can be found in a number of books, including Basic Business Statistics by Mark Berenson and David Levine. You may also enjoy the less complete (but more readable) treatment in The Cartoon Guide To Statistics by Larry Gonick and Woollcott Smith.