Semiconductor cluster tools are used to process semiconductor wafers for the fabrication of microelectronic components. A typical semiconductor cluster tool is comprised of several different wafer processing modules that are managed by a centralized control system. Semiconductor cluster tools combine the wafer processing chambers with a wafer handling robot to minimize contact with the wafers. The semiconductor cluster tool control system then manages the wafer’s travel between each chamber. The type of chambers used can include process, transport, buffer and cassette modules. Cassette modules are used to store both processed and unprocessed wafers. Process modules perform manufacturing techniques such as deposition, etching, and planarization. Transfer modules move the wafers between the process and cassette modules.
Semiconductor cluster tools allow wafers to be processed in a closed environment with little operator interaction. A semiconductor cluster tool may be one of two basic types: a cluster tool with a single wafer handling chamber between the loadlock and the process chambers, or a cluster tool with two or more chambers. Typical semiconductor cluster tools should not exceed 10 m2. There are several common causes for the failure of semiconductor cluster tools. These causes include resist on the wafers, isopropyl alcohol contamination, incoming gas irregularities, incorrect gas mixtures, high levels of fluorine or chlorine in the buffer chambers, or internal leaks.
Demands for smaller diameter wafers, improved device performance, and greater reliability and yield are drivers for the development of cluster tools for semiconductor processing operations. The semiconductor manufacturing industry is moving towards a cluster approach for semiconductor equipment in order to create a higher throughput for wafer processing. The purpose of semiconductor cluster tools is to reduce cycle times, reduce wafer handling by operators, and reduce particulate and molecular contamination. Although the Semiconductor Equipment and Materials Institute (SEMI) sets standards for semiconductor cluster tools, these standards are not yet accepted by some of the largest suppliers.