Papers by Author: Jeffery W. Butterbaugh

Abstract: Silicon nitride is commonly etched by hot orthophosphoric acid. Hot diluted hydrofluoric acid is hereby used as an alternative. Nonetheless, in presence of silicon surfaces, some corrosion has been evidenced, degrading significantly active areas during the STI (Shallow Trench isolation) integration. Oxygen in hot deionized water or hot HF generates this corrosion and selecting a relevant chemical oxide before dispensing hot diluted HF is key in solving the concern.

Abstract: Selective nitride etching in semiconductor manufacturing is currently performed in wet benches using hot orthophosphoric acid at 160-180C. This process requires silica seasoning to achieve the desired selectivity to silicon oxide. Silica seasoning in wet benches is achieved by etching blanket silicon nitride wafers prior to running productions runs. While, this method of selective silicon nitride etching has been successful in the past, particle requirements at advanced nodes [1] are driving the need for a new solution. Single wafer wet processing is proposed as a way to meet these challenging new particle specifications.

Abstract: Selective etching of silicon nitride films has been an important process step in integrated circuit manufacturing for many years [1-. In the past, this process has been mainly used to remove the silicon nitride mask which protects the transistor active area during the formation of oxide isolation. Recently, this process has also been used to remove silicon nitride spacers after source and drain formation for better management of the strained channel [. Advanced device integration continues to add more steps in which the selective removal of silicon nitride is needed.

Abstract: Photoresist stripping in IC manufacturing has become more challenging as the number of photoresist levels has increased while at the same time allowable material loss and surface damage has decreased. Heavily implanted photoresist is especially challenging due to the dehydrogenated, amorphous carbon layer that forms on the surface [1]. To facilitate implanted photoresist removal, this layer can be attacked by physical processes such as ion bombardment as part of the common dry ashing approach. However, these physical approaches can lead to surface damage and increased material loss. Another approach is to increase the reactivity of the sulfuric acid – hydrogen peroxide mixture (SPM), so that it can penetrate and dissolve the amorphous carbon layer and achieve complete photoresist removal.