Songyuan Xie

Organosiloxane based bottom antireflective coating for 193nm lithography

A spin-on sacrificial 193 nm UV absorbing organosiloxane film was developed to facilitate ArF photoresist (PR) patterning. To improve lithographic compatibility with acrylate based photoresists, different performance additives were evaluated as photoresist adhesion promoter. The results suggested that the type and loading of the photoresist adhesion promoter had a large impact on the profile and focus latitude of the patterned photoresist features. An efficient photoresist adhesion promoter candidate was identified, which has minimum impact on other solution and film properties. This work has led to the development of DUO 193 organosiloxane based bottom anti-reflective coating. Application of this film as a blanket level bottom anti-reflective coating or as a fill material for via first trench last (VFTL) dual damascene patterning is possible. The SiO structure intrinsic to this film provides a high degree of plasma etch selectivity to the thin ArF photoresists in use today. Furthermore, an equivalent plasma etch rate between DUO 193 and the low dielectric constant SiOCH films used as the dielectric layer in the backend Cu interconnect structure is possible without compromising the photoresist etch selectivity. Equivalent etch rate is necessary for complete elimination of the “fencing” or “shell” defects found at the base of the etched trench feature located at the perimeter of the top of the via. Advanced ArF PR features of 100 nm in width (and smaller) have been routinely patterned on DUO 193 film. Via fill, plasma etch rate, wet etch rate, ArF PR patterning and shelf life data will be discussed in this presentation.

A high-Si content middle layer for ArF trilayer patterning

This work discusses the development and characterization of Honeywells middle layer material, UVAS, for trilayer patterning. The UVAS polymer contains high Si content constructed by polymerizing multiple monomers selected to produce a film that meets the requirements as a middle layer for trilayer patterning. Results of ArF photoresist patterning evaluations, plasma and wet etch studies, and photoresist and full stack rework tests will be presented and discussed. ArF photoresist patterning tests show that UVAS exhibits organic BARC like performance with respect to MEEF (Mask Error Enhancement Factor), DOF (Depth of Focus) and EL (Exposure Latitude). Shelf life data shows that UVAS maintains very stable properties even after 6 months storage at room temperature. We will also briefly discuss investigation of amine or nitrogen-based contaminant blocking by the UVAS middle layer.

Performance of an ArF siloxane BARC exposed to a 172-nm UV cure for double patterning applications

As IC manufactures explore different paths to meet the resolution requirements for next generation technology, patterning schemes which utilize a double photoresist patterning process are under extensive evaluation. One dual patterning process under consideration uses a 172nm UV cure to render the first photoresist pattern insoluble to the casting solvents and developer chemistries used to define the second photoresist pattern. In this work we investigate the change in the material properties such as thickness, optical, bond structure, adhesion and stability of the SiBARC film due to the UV cure. Simulations are included to assess the change in substrate reflectance due to the change in the optical properties of the SiBARC film as a result of the UV cure. Single patterned photoresist line space features versus UV cure dose of the SiBARC - under layer film stack is presented. This is followed by cross-grid and pitch-split double patterning using 172 nm UV light of varying dose to freeze the first photoresist layer patterned using a tri-layer film configuration.

Pattern Collapse-Free Drying with Sacrificial Gap Fill Polymers

This work discusses pattern collapse-free drying by application of a sacrificial polymer during the semiconductor wafer cleaning process. The sacrificial polymer is dispensed onto the wafer, displacing the rinse liquid and subsequently dried to form a solid polymer fill within the patterned structure, providing both mechanical support and a means for dry polymer removal by either plasma or thermal exposure. Polymer film thickness, gap fill capability and removal rate are explored for plasma ashable and thermally removable polymer families.

High-Si content BARC for dual-BARC systems such as trilayer patterning

This work discusses the requirements and performance of Honeywells middle layer material, UVAS, for tri-layer patterning. UVAS is a high Si content polymer synthesized directly from Si containing starting monomer components. The monomers are selected to produce a film that meets the requirements as a middle layer for tri-layer patterning (TLP) and gives us a level of flexibility to adjust the properties of the film to meet the customers specific photoresist and patterning requirements. Results of simulations of the substrate reflectance versus numerical aperture, UVAS thickness, and under layer film are presented. ArF photoresist line profiles and process latitude versus UVAS bake at temperatures as low as 150ºC are presented and discussed. Immersion lithographic patterning of ArF photoresist line space and contact hole features will be presented. A sequence of SEM images detailing the plasma etch transfer of line space photoresist features through the middle and under layer films comprising the TLP film stack will be presented. Excellent etch selectivity between the UVAS and the organic under layer film exists as no edge erosion or faceting is observed as a result of the etch process. A detailed study of the impact of a PGMEA solvent photoresist rework process on the lithographic process window of a TLP film stack was performed with the results indicating that no degradation to the UVAS film occurs.

High Si content BARC for applications in dual BARC systems such as tri-layer patterning

This work discusses the requirements and performance of Honeywells middle layer material, UVAS, for trilayer patterning. UVAS is a high Si content polymer synthesized directly from Si containing starting monomer components. The monomers are selected to produce a film that meets the requirements as a middle layer for trilayer patterning and gives us a level of flexibility to adjust the properties of the film to meet the customers specific photoresist and patterning requirements. Results of simulations of the substrate reflectance versus numerical aperture, UVAS thickness, and under layer film are presented. Immersion lithographic patterning of ArF photoresist line space and contact hole features will be presented. A sequence of SEM images detailing the plasma etch transfer of line space photoresist features through the middle and under layer films comprising the TLP film stack will presented. Excellent etch selectivity between the UVAS and the organic under layer film exists as no edge erosion or faceting is observed as a result of the etch process. The results of simulations of Rsub versus NA, and the thickness of each film comprising a two layer antireflective film stack will also be discussed.