Improving minienvironment process control requires monitors providing immediate and accurate data sets. This data sets should clearly illustrate the minienvironment's cleanliness and ability to perform processes without adding particles to wafers. This process control is especially important as minienvironments age and the doors, seals, and robotics tend to wear. Without minienvironment monitors, the process control can quickly degrade and adversely impact product yields.

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Process Challenges

• Minienvironments are small, sometimes densely populated, spaces. Any monitor should fit within small confines and not hinder the minienvironment's processes.
• Monitors should evaluate both differential air pressure and particle activity. Since the minienvironment sustains positive pressure with respect to the fab, decreases in differential pressure could signify enclosure deterioration and allow particle ingress.
• Wafers quickly pass through most minienvironments, so any monitor should provide immediate and accurate data.
• Monitors correlating both differential air pressure and particles will provide a clear, concise report of the minienvironment's process and efficiency.

Process Solution

• The MiniNet® monitor simultaneously monitors both differential air pressure and particle activity.
• The MiniNet Monitor includes seven sample lines attached to an ensemble manifold. This provides particle data from seven distinct locations within the minienvironment.
• Better coverage means better analysis.
• The MiniNet monitor communicates all data through an on-board 10Base-T (Ethernet), which provides remote data analysis and trending reports.
• Monitoring both differential air pressure and particles provides more valuable information than monitoring only differential air pressure.

300 mm Ion Implantation Tool

Graph 1 (Download this paper for all tables and figures) (501.6 KB)

• MiniNet monitor particle data from an Applied Materials ion implant tool
• The ion implant tool is located in a large 300 mm fab in the United States
• The fan filter units (FFUs) critically failed on this tool
• In the first indication of impending failure on the left of the chart; particle activity increased as differential pressure decreased. This was a temporary stalling of the FFUs
• Just over two days later, the FFUs stopped operating
• Engineers noticed the particle activity and attached a zero-count filter to the MiniNet monitor at 11:30. The MiniNet monitor particle activity dropped to zero.
• Confident the MiniNet monitor was properly operating, engineers turned their attention to the ion implanter tool
• At 11:00 the next morning, engineers noticed the tool's FFUs were not operating
• After successful replacement of the FFUs, particle activity and differential pressure returned to normal levels
• The final particle spike and pressure drop are attributable to tool maintenance and re-inspection of the FFUs

300 mm Photolithography Data

Graph 2 (Download this paper for all tables and figures) (501.6 KB)

• MiniNet monitor particle data from a TEL photolithography tool
• The photolithography tool is located in a large 300mm fab in Southeast Asia
• The yellow line (at 120 particle counts) represents an alarm condition
• The alarm level was exceeded 24 times
• Those wafer lots processed during particle alarms were subjected to intense scrutiny

300mm Wafer Probe Data

Graph 3 (Download this paper for all tables and figures) (501.6 KB)

• MiniNet monitor particle data from a TEL wafer prober tool
• The wafer prober tool is located in a large 300mm fab in the United States
• The yellow line (at 6000 particle counts) represents an alarm condition
• The alarm level was exceeded 6 times
• Frequently, particle alarm levels were accompanied by increases in differential pressure
• We suspect positive pressure within the wafer prober caused particles to pass across wafer as they exhaust
• The process area was thoroughly inspected and cleaned

300mm Surface Scan Data

Graph 4 (download pdf for all images)

• MiniNet monitor particle data from a KLA-Tencor surface scanning tool
• The surface scan tool is located in a large 300mm fab in the United States
• The yellow line (at 5 particle counts) represents an alarm condition
• The alarm level was exceeded once
• This particle alarm was accompanied by an increase in differential pressure
• We suspect positive pressure within the surface scanner alighted particles and re-deposited them onto the wafer
• The process area beneath the scanning pad was thoroughly inspected and cleaned

300mm Lot Sorter Data (tool 1)

Graph 5 (download pdf for all images)

• MiniNet monitor particle data from a Recif lot sorter tool
• The surface scan tool is located in a large 300mm fab in the United States
• The yellow line (at 2 particle counts) represents an alarm condition
• The alarm level was exceeded twice
• This particle alarm was accompanied by a decrease in differential pressure
• We suspect negative pressure allowed particle ingress and deposition onto the wafer
• The front-opening-unified pod (FOUP) doors were examined for leakage and alignment

300mm Lot Sorter Data (tool 2)

Graph 6

• MiniNet monitor particle data from a Recif lot sorter tool
• The surface scan tool is located in a large 300mm fab in the United States
• The yellow line (at 2 particle counts) represents an alarm condition
• The alarm level was exceeded twice
• Again, particle alarms were accompanied by a decrease in differential pressure
• We suspect negative pressure allowed particle ingress and deposition onto the wafer
• The front-opening-unified pod (FOUP) doors were examined for leakage and alignment

MiniNet® is a registered trademark of Particle Measuring Systems, Inc.