Paper PS-WeM11
Tone Reversal Technology Development Targeting Below 5nm Technology Node Applications

Wednesday, November 1, 2017, 11:20 am, Room 23

For many decades, the semiconductor industry could follow Moore’s law by introducing innovative device architectures, smart design, new integration and patterning concepts, better tools and new materials. While industry is almost ready for high volume manufacturing of the 7nm technology node, new approaches are constantly being tested by research centers to enable further scaling down to the 5nm technology node (N5) and below. In order to enable a number of these new integration approaches, there is a growing need for a well-understood and well-controlled tone reversal technology that consists of inverting the tonality of all structures present on the wafers, such as inverting ~20nm holes to blocks and sub-20nm lines to trenches, as well as large (micrometer-sized) structures such as alignment marks and overlay targets. The multiple Litho-Etch (LE) block patterning, the Self-Aligned Block (SAB) concept or the Direct Metal Etch (DME) approach are few examples of applications that advantageously integrate such tone reversal technology. A typical tone reversal flow consists of filling the patterns to be inverted with a material that could be either spin-coated or deposited. By means of dry etching or chemical mechanical polishing (CMP), the filling material is then thinned down to the top of the filled patterns which are finally selectively pulled out leaving the reversed patterns behind. A PECVD/ALD-type of filling would generally lead to the formation of voids between the patterns and to a low planarization performance requiring the use of an expensive CMP step that has a limited process window. Spin-coated materials are providing a good alternative to PECVD/ALD layers as they offer the possibility to achieve void-free filling and good planarization performance through material and process optimization. In this work, we focus on a fundamental understanding of the planarization properties of spin-coated materials. More specifically, the filling properties and planarization of different spin-coated materials (spin-on-glass, spin-on-carbon or spin-on-metal oxides) are screened in a selection of relevant matrix materials. By means of High Resolution Profiling, top-down and X-section Secondary Electron Microscopy the planarization properties are characterized as a function of pattern size, density and aspect ratio. Finally, the performances of the most promising tone reversal technologies are evaluated on concrete N5 and N3 applications like SAB and DME.