Modification of organic underlayers by plasma during dry etching and its effect on the film properties

The manufacturing process of advanced logic devices has become ever more challenging than before due to continued shrinkage in dimensions from scaling down and increased complexity from the integration of new transistor structures such as gate-all-around (GAA). Underlayers are utilized as a mask to protect targeted device structures while selected areas of deposited metal is removed by wet etchant during replacement metal gate (RMG) process to construct the transistor. Reported studies describing the developmental strategies for such underlayers have been mostly focused on how to strengthen the adhesion towards the substrate with the designed film properties. In this paper, we identify the effect of plasma during dry etching of the RMG process as the factor to be considered in designing of the wet etch resistant underlayer. Physical and chemical properties of organic films after dry etching with plasmas of different gases have been investigated using various analysis techniques, and the subsequent effect of plasma-modification on the film properties such as resistance towards wet chemicals for various films was evaluated.