BACKSIDE COOLING METHOD FOR POWER DEVICES
Original Publication Date: 1996-Nov-01
Included in the Prior Art Database: 2002-May-08
Analysis has shown that future technology to be employed in power device designs wihhkely result in higher than desirable temperatures behrg gener- ated during device operation. Since the conduction lengths (Z W, where a is the thermal diffusivity) characteristic of silicon are much smaller than typi- cal substrate thicknesses, the heat generated during high power operation cannot be removed effectively Under such conditions, the temperature rise due to this heat generation scales as: EIA ATmax cc ,Cpkr)1t2 where E/A is the energy per unit device area gener- ated, p is the material density, C, is the material heat capacity, k is the material thermal conductivity, and I is the time associated with thermal transients (e.g., the time over which heat must be dissipated). Two options are available to reduce this maximum temperature: (i) mechanically thin the substrate to below the conduction length of silicon, or (ii) replace low (p C k)'12 material (e.g., silicon) with high (p C, k$ material (see Figure 1).