1. Technical Field
The present invention relates to cooling systems in general, and in particular to a thermoelectric cooling system. Still more particularly, the present invention relates to a thermoelectric cooling system for cooling integrated circuit devices.
2. Description of the Prior Art
The fact that integrated circuit (IC) devices can operate faster as temperature decreases is well-known in the art. For example, the performance of an IC device improves by 50% when operated at -50.degree. C. instead of ambient room temperature, and a 200% speed improvement can be achieved by cooling the IC device with liquid nitrogen to -196.degree. C. Similar performance improvements have also been observed on interconnects within the IC device. For example, interconnect resistance decreases by a factor of two when the IC device is operated at -50.degree. C. rather than at ambient room temperature. Thus, IC device performance can be significantly benefited by sub-ambient temperature, which begs the question of how to cool IC devices to a sub-ambient temperature in an efficient and cost effective manner.
Conventionally, sub-ambient cooling is accomplished through gas/liquid vapor compression-based cooling systems, using Freon-type refrigerants to provide heat transfer. Although vapor compression-based cooling can be quite efficient, a significant amount of hardware, which includes at a minimum, a compressor, a condenser, an evaporator, and related coolant transfer plumbing, is required. As a result, vapor compression-based cooling has not found general acceptance for cooling small objects such as IC devices.
A more promising method for cooling IC devices is thermoelectric cooling. In addition to being compact, thermoelectric devices such as Peltier devices are also very reliable because they are typically have no associated moving parts. However, a key negative aspect of thermoelectric devices is their inefficiency. A Peltier device cooling system typically has an efficiency of approximately 20% for a relatively nominal temperature differential between a cold sink and the ambient room temperature. For example, if a Peltier device cooling system is utilized to cool at a rate of one watt to attain a sub-ambient temperature of 0.degree. C., five watts will be required to power the Peltier device cooling system. Also, as the amount of heat required to be transferred increases, the total power needed to be dissipated into the ambient environment mandates large convection devices and large power supply circuits. Thus, Peltier device cooling systems have not been considered a broadly applicable technology for cooling IC devices either. Consequently, it would be desirable to provide an improved thermoelectric system for producing thermoelectric cooling on IC devices.