Corrective selective hard mask growth for High NA patterning

Challenges introduced with High NA EUV lithography will be defectivity management with ultra-thin resists while using low EUV dose¹. Reducing the density of bridges and breaks is thus a major point of focus for its introduction². Ultra-thin resists, at low EUV dose, may come with high bridge/ break density (positive/ negative-tone resist, respectively). In the case of bridges, a descum step is traditionally introduced, which creates breaks instead (in ultra-thin resists) and further reduces the resist budget for underlayer patterning. Therefore, recovering breaks is a strategic capability for defect reduction.

The goal of the instership work is to study the inner workings of existing processes to enable similar processes in other applications. The method consists of patterning an underlayer of suitable thickness for ultra-thin resists, and run a PECVD deposition process onto this underlayer, selectively to the material below in order to prevent and recover breaks. This way, the hard-mask budget is increased to prevent the formation of breaks during transfer into the stack, even and especially while patterning from an ultra-thin underlayer. Additionally, this method offers a reduced environmental footprint compared to conventional one as no or much thinner UL can be used requiring no or less high global warning potential gases to be used.

More specifically, you will:

• Study the thermo-mechanical properties of the deposited material.
• Develop post deposition processes to adapt the film properties and composition to the targeted application,
• Investigate mechanisms of different defect mitigation approaches (atomic clean, super cycle, etc.),
• Identify the nucleation mechanisms on ultrathin layer.