1) Ion beam etching (IBE) has the capability to remove any material by a purely physical process. This process is sometimes called sputtering. Considered a universal etchant process method, IBE can etch metals, alloys, insulators, semiconductors, carbon-based materials and any multilayers or composites thereof. IBE can accurately control the rates of removal of these materials by its ability to precisely control the ion beam properties. These ion beam properties such ion energy, ion current density, incidence angle fundamentally determine the physical sputtering phenomena.
2) By selecting the correct feed gases when designing the ion beam etch process, the etch rates of materials can be optimized to preferentially remove one material over another. This optimization is called material etch selectivity. In ion beam etching, the ability to include variable process gases promotes and supports similar removal rates of the different materials found in an IC layer. The uniform removal of different materials produces quality common planar surfaces sought in delayering.
3) Ion beam etching will remove tens of micrometers of material which is well suited to etch the IC’s thick upper passivation layer. But, it’s the capability to precisely and repeatability remove atomic levels of material which is a key advantage in the delayering field. The IBE process range of operation enables gentle removal rates which allows delayering resolution at the nanometer scale. The predictability of this precision control to stop on the desired layer overcomes the undershoot or overshoot risks in the prevailing methods.
4) The surface of the IC chip does not always present a flat starting layer. Some of the top layers may have structures which protruded from the layer. A good delayering method will possess the ability to planarize or smooth the surface, removing these protruded features. Ion beam etching is uniquely suited to etch these structures with its capability control the incidence angle of the beam as it strikes the surface. In doing so, it can enhance the removal selectivity of these elevated structures over the base layer, eventually smoothing out the layer. Without the use of polishing slurries as done with mechanical force polishing, ion beam etching polishes the surfaces by removing material on the atomic/molecular scale.
5) The size of the broad ion beam is large when compared to IC chips. Therefore, ion beam etching is naturally suited to uniformly remove material from IC layers. The even distribution of processing power across a 25mm x 25mm IC chip can etch material with less than 1% non-uniformity. Consequently, the objective to form a common layer and propagate common layers deeper into the IC structure is readily achievable with our ion beam etching method.
6) When compared to the prevailing methods, ion beam etching does not present the invasive side-effects that can distort the layer and interfere with the integrity of the subsequent measurements and analysis. Ion beam etch avoids the residual contamination and damage as might occur with mechanical polishing methods. Ion beam etching avoids layer corrosion or percolation of fluid chemicals to lower layers in the IC as might happen in the wet chemical etch. In ion beam etching, the IC chip is not immersed in a high-density plasma as in the dry plasma etch method. When the IC chip is immersed in the plasma it is exposed to heat and radiation which can possibly alter surface material from its native state. Ion beam etching minimizes exposure to the bulk plasma, therefore reducing temperature and radiation concerns.