In-line CD metrology with combined use of scatterometry and CD-SEM

Abstract

Measurement characteristics in scatterometry and CD-SEM for lot acceptance sampling of inline critical dimension (CD) metrology were investigated by using a statistical approach with Monte Carlo simulation. By operation characteristics curve analysis, producer's risk and consumer's risk arising from sampling were clarified. Single use of scatterometry involves a higher risk, such risk being particularly acute in the case of large intra-chip CD variation because it is unable to sufficiently monitor intra-chip CD variation including local CD error. Substituting scatterometry for conventional SEM metrology is accompanied with risks, resulting in the increase of unnecessary cost. The combined use of scatterometry and SEM metrology in which the sampling plan for SEM is controlled by scatterometry is a promising metrology from the viewpoint of the suppression of risks and cost. This is due to the effect that CD errors existing in the distribution tails are efficiently caught.

Metrology in times of shrinking budgets

“…In parallel to this, references [12][13][14][15][16][17][18][19][20][21][22] are the winning papers of the Diana Nyyssonen Award, given annually to the paper which is judged the best paper of the Conference by the members of the Program Committee [24]. These papers deal more specifically with the technologies developed to make measurements: 6 deal with scatterometry, and 4 with CD SEM.…”

Verification metrology system by using inline reference metrology

“…A new measurement technology with higher accuracy for inline metrology has only been developed recently. For example, combination systems of several metrology tools have been put to practical use, such as double metrology 3 and hybrid metrology. 4 To improve the MU, advances in inline metrology and reference metrology in production are needed.…”