Monitoring particulate contaminants in a metal etch system

Summary form only given, as follows. Four alternative methods of monitoring particulate contaminants on the LRC 4600 metal etch cluster tool are described The etch process involves the formation of polymeric byproducts that protect metal sidewalls from being undercut. These byproducts also adhere to the tool's chamber walls. Deposition of polymeric flakes on the wafer during the etch process blocks the etch and results in metal shorts. Therefore, regular monitoring and control of particles is a necessity. The monitoring schemes include the use of bare silicon wafers under a plasma-off environment and the use of photoresist coated wafers under plasma-on conditions. Regularly scheduled line monitors (LMs) that simulate the product flow are also processed through each metal etch tool to detect and prevent failures in the backend of the wafer fabrication process. In addition, an in-situ particle monitor (ISPM) is used to monitor particles exiting in the main etch chamber's exhaust line. In order to minimize test wafer usage and cycle-time an attempt was made to correlate the various monitoring schemes, the results of which are described.