NO. SC - 801
SC TECHNOLOGY APPLICATION NOTE
Feed-Back Or Feed-Forward, Your Choice
The INS 800 series instruments are capable of real time, in-line measurements of thickness and reflectivity properties of semi-transparent substrate layers, photoresists, and other semi-transparent films. In addition, the INS 800 systems may be equipped to facilitate real-time, in-line control of many develop processing tracks.
Insure Process Results With No Throughput Costs
The INS 800 products utilize patented hardware and data analysis processes (SC Technology, US Patents 4,977,330 and 4,938,555) that facilitate a broad spectrum of application capabilities. "Snapshots" of reflectivity of more than 500 wavelengths are collected, processed, and an absolute thickness is calculated within ½ second. Thickness calculation algorithms employ a simultaneous correlation of 512 discrete wavelengths, which provide thickness measurements of unequaled accuracy, reproducibility and reliability. Unlike commercial in-line "end-point-detection" systems, the INS 800 products can instantaneously provide real thickness information in real-time. The INS 800 technology lends itself equally well to both coat and develop process applications.
Multiple Applications Enhance Cost Effectiveness
Coating Process In-Line Inspection
When configured for use in coating applications, the INS 800 products perform in-line, real-time thickness and reflectivity measurements of semi-transparent substrate layers and photoresist films. Every product wafer may be automatically measured in real-time thereby eliminating the need for off-line QA inspections which typically impact process through-put and require manual handling of product wafers.
The INS 800 system is capable of alerting the operator and providing identification of the wafers which are beyond the desired tolerance limits specified for the process whenever the system detects unwanted changes in sublayer thickness, photoresist thickness and/or reflectivity. Suspect wafers may then be inspected in finer detail with off-line inspection equipment to isolate and identify specific processing problems before subsequent processes are performed.
The INS 800 is also capable of saving any or all measurement data for every wafer or select wafers. This feature facilitates automation of in-line SPC data logging.
Develop Process In-Line Inspection & Control
The INS 800 series products are also designed for use in develop applications. The INS 800 products perform in-line, real-time thickness and develop rate measurements of photoresist films during the develop process. In addition to performing measurements, the INS 800 is capable of dynamically controlling the develop process in order to minimize the effects of pre-develop processing errors which will adversely impact feature CD’s.
Changes in photoresist coating thickness, substrate layer reflectivity, soft-bake temperature and exposure energy, to name a few, translate to changes in the photoresist development rate and the resulting feature CD’s. When using the INS 800 in the develop mode, a change in development rate is detected in real-time and the INS 800 can instruct the develop equipment to either shorten or lengthen the development process in order to yield the correct feature CD’s.
The INS 800 is capable of saving any or all develop data for every wafer or selected wafers.
In-Line Automated SPC Data Acquisition
INS 800 systems provide capabilities to automatically log all data for all wafers or selected data and/or selected wafers. Windows platform software is available for the INS products which provide off-line analysis utilities:
- SPC analysis
- Database management
- Process capability analysis
Process & Materials R&D
Windows platform software is available for the INS 800 systems which provide a variety of data processing utilities to streamline process and material characterization applications:
- Data processing and conversion utilities for data export to CD modeling programs
- Exposure matrix analysis for matrices of up to 50 wafers
- 2, 3, 4, & 5 parameter numerical models for a variety of curve fitting applications:
- Thickness vs. Time
- Normalized Thickness vs. Log Exposure
- Average Develop Rate vs. Log Exposure
- Absolute Develop Rate vs. Log Exposure
- Time-to-Clear vs. Log Exposure
- Develop Rate vs. Film Depth
- Database generation, maintenance, and spreadsheet export utilities
- Process variable effects analysis:
- Inhibition Layer Develop Rate vs. Process Parameter
- Bulk Layer Develop Rate vs. Process Parameter
- Clear-Time vs. Process Parameter
- Coating Thickness vs. Process Parameter
- Reflectivity vs. Photoresist Layer Thickness
- Reflectivity vs. Substrate Layer Thickness
- Reflectivity vs. Resist/Sub-Layer Thickness Ratio
- CD vs. Measured Parameter
Process Cell Matching
Many of the utilities used for process and material R&D applications serve equally well for process cell matching and equipment-to-equipment performance characterization. The process variable effects analysis module is particularly useful for these applications. Process data may be collected from each process cell and compared via numerical analysis and/or graphical overlays. These utilities enable the user to quickly identify even subtle differences in processing equipment functional performance and provides the user with the appropriate qualitative and quantitative information necessary to functionally match processing cells and equipment performance.
Compatibility Issues Solved
INS 800 systems are compatible for use with most patterned and unpatterned substrates, substrate sizes, photoresists, and semi-transparent films (100 Angstrom to 10 micron application range). For development process applications, an exposed area/die of approximately 10% or greater is recommended (20% for applications employing high reflectivity substrates such as aluminum). INS 800 systems are compatible for use in spray, spray-puddle, stream, and double-spray-puddle development applications. Sampling areas are adjustable from approximately 1mm to 12mm (larger spot sizes, up to 20mm are possible with an accompanying loss in signal intensity). Probe working distances can range from a few inches up to approximately 20 inches (<10 inches is recommended). Probes occupy such a small space that mounting and alignment are relatively simple without the need for modifications to the track or station hardware. The incident source is external to the probe. This eliminates the possibility of an undesired thermal source within a processing chamber. Additionally, the light source incorporates a transmission cut-off filter to ensure that no actinic UV energy is imparted upon a photoresist film. Ins 800 digital I/O’s and serial communications are compatible for use with the vast majority of commercial coat and develop track systems.