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Method for a solid-state active chip-cooling device

IP.com Disclosure Number: IPCOM000131867D
Publication Date: 2005-Nov-21
Document File: 5 page(s) / 106K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a solid-state active chip-cooling device. Benefits include improved functionality, improved performance, improved thermal performance, and improved ease of manufacturing.

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Method for a solid-state active chip-cooling device

Disclosed is a method for a solid-state active chip-cooling device. Benefits include improved functionality, improved performance, improved thermal performance, and improved ease of manufacturing.

Background

              An industry trend is for devices to be scaled down in size while performance increases. One result is increased local heat dissipation. The situation is more severe for mobile products due to their compact design and increased battery life requirements.

              Conventionally, chip heat dissipation is addressed through a combination of thermal interface materials, a heat spreader, a heatsink, and an electrical fan. However, these solutions provide low heat dissipation efficiency and large device packaging size.

              An alternative solution uses a vacuum or air gap as the insulating barrier medium, and dissipates heat through an electron tunneling effect. Tunneling occurs when two metals with different work functions are separated by a thin insulating barrier and biased with the low work function metal as the cathode. Electrons with high kinetic energy tunnel through the barrier. When across the barrier, the hot electrons become trapped at the anode side. If the barrier can block the heat radiation back to the cathode side, all of the heat carried by the hot electrons can be dissipated through conventional solutions. As a result, the cathode temperature is cooler than the ambient temperature (see Figure 1).

              One solid-state solution is a device which utilizes an air gap. It is created by depositing and removing a sacrificial layer. The gap is maintained by an array of piezo-electric positioners. This solution requires a complicated manufacturing method at device packaging operation and has limited applications due to the high cost.  

General description

              The disclosed method is a thin-film device for active chip-cooling applications. The device is comprised of a highly conductive and low work function cathode, a cathode cap, a thin dielectric barrier and a highly conductive anode. The device is biased to generate hot electron tunneling from the cathode side (backside) of a wafer and dissipate heat from an active chip. The device is fabricated in a typical wafer fab with no special equipment or processing requirements. The device has a broad range of applications in the microelectronics industry.

              The key elements of the disclosed method include:

•             Cathode comprised of a highly-conductive metal layer and a low work function surface coating

•             Cathode cap is a dense inorganic layer providing a hermetical seal of the cathode and preserve its work function characteristics

•             Anode is a highly-conductive metal layer

•             Insulating barrier is a polyimide isolated air gap to separate the cathode and the anode

•             Manufacturing process of the device

Advantages

 

              The disclosed method pro...