The effect of various wafer thicknesses on hot spot temperature

Hot spots on thin wafers of IC packages are becoming an important issue in thermal and electrical engineering. To investigate these hot spots, we developed a diode temperature sensor array (DTSA) that consists of an array of 32 times 32 diodes (1,024 diodes) in an 8 mm x 8 mm surface area. We used chemical-mechanical planarization to make DTSA chips with various thicknesses (21.5 mum, 31 mum, 42 mum, 100 mum, 200 mum, and 400 mum). In addition, we conducted the experiment with various heater power conditions (0.2 W, 0.3 W, 0.4 W, and 0.5 W). Finally, on the basis of the experimental results, we propose a correlation for the hot spot temperature as a function of the generated power and the chip thicknesses. This correlation can give an easy estimate of the hot spot temperature for flip-chip packaging when the wafer thickness and the generated power are given.