Graded-Density Filter Technology
The Planargard filter relies on a graded-density depth filter design that enables it to retain defectcausing agglomerates in each of its four layers. This design provides excellent retention of agglomerates while allowing desired slurry particles to reach the surface of the wafer. Because particles are retained throughout the filter matrix rather than on a single surface, the potential for premature filter “plugging” is greatly reduced.
Performance
Planargard filters remove only those particles that are disruptive to the CMP process, not all particles. The particle size distribution of the desired slurry particles does not change after filtration. As a result, consistent slurry is delivered to your process.
Filter Selection
Mykrolis offers Planargard filter options to match your application filtration objectives. For example to minimize wafer defects when polishing a polysilicon layer, a tight structure (i.e., CMP5) is recommended. If filter life is a priority, a more open structure (i.e.,CM13) may be used. Mykrolis’s worldwide technical support team stands ready to support you with product recommendations and evaluation assistance.
The Effect of Filtration on Working Particles
Results of tests conducted by Mykrolis demonstrate that Planargard cartridges do not affect the particle size distribution of working particles. Our testing also shows that filters tighter than CMP1 can remove desirable working particles, causing premature plugging and reduced removal rates.