A classic is Tuckerman's and Pease's work:

D. B. Tuckermann, R. F. W. Pease, "High-Performance Heat Sinking for VLSI", IEEE
Electron Device Letters, Vol. 2, 1981, pp. 126-129.

We have done some research more recently:

T. M. Harms, A. Hölke, J. Pilchowski, M. Kazmierczak, F. Gerner, H. T.
Henderson, K. Baker, "Experimental Investigation of Heat Transfer and Pressure
Drop Through Deep Microchannels in a (110) Silicon Substrate", Proceedings of
the 1997 International Mechanical Engineering Congress and Exposition, Dallas,
TX, November 16-21, 1997

--
Alexander Hölke
graduate assistant
University of Cincinnati
Center for Microelectronic Sensors and MEMS
Phone:  (513)556-1997
FAX:    (513)556-7326