Thermal distribution has become an important reliability concern for today's integrated circuits. In traditional design flows, the temperature of the chip is assumed to be uniform across the substrate. However, non-uniform thermal distribution can be a major source of inaccuracy in delay and clock skew computations, and can have an impact on electro-migration reliability and self-heating effects. Hence, it has become necessary to obtain design with uniform temperature distribution to ensure minimum temperature gradient and avoid hot spots across the chip area. The uniform temperature distribution can be achieved by appropriate placement of circuit blocks during the physical design. However, placement should take into account factors such as area, aspect ratio and timing closure issues. Thus the design process becomes a multi-objective optimization problem, which we are solving using a genetic algorithm.