A unifying model based on enhanced elctron-hole recombination rate generated by surface plasmon (SP) waves of Au
nanoparticles (NPs), electrons transferred from the CdSe quantum dots (QDs) to the Au NPs, as well as the
photoexcitation wavelength is proposed to explain the observed optical enhancement and quenching from Au and CdSe
nanocomposites. In our system, the photoluminescence-enhancement ratio can be manipulated to ~130, the largest value
ever reported. Our experimental results clarify the ambiguity in controlling the light emission enhancement of
semiconductor nanocrystals which are coupled with the SP waves of metal NPs.
As a continuation of comparison experiments between EUV inspection and visible inspection of defects on EUVL mask blanks, we report on the result of an experiment where the EUV defect inspection tool is used to perform at-wavelength defect counting over 1 cm<SUP>2</SUP> of EUVL mask blank. Initial EUV inspection found five defects over the scanned area and the subsequent optical scattering inspection was able to detect all of the five defects. Therefore, if there are any defects that are only detectable by EUV inspection, the density is lower than the order of unity per cm<SUP>2</SUP>. An upgrade path to substantially increase the overall throughput of the EUV inspection system is also identified in the manuscript.
In this paper, the printability of Extreme ultraviolet (EUV) mask contact layer defects at 90 nm contact size and above is studied via ultra-thin DUV resist and 10X EUV Microstepper. The EUV mask contact defect size requirement is determined by taking into account the wafer process critical dimension (CD) variability. In the experiment, two types of contact mask defect were studied. They are opaque defect placed at both edge and center of a contact and clear defect at edge of a contact. The programmed EUV absorber defect mask was fabricated by subtractive metal patterning on a Mo/Si multilayered-coated silicon wafer substrate. The 10X experimental EUV lithography system with 13.4 nm exposure wavelength and 0.088 NA imaging lens was used to expose the programmed defect mask. The response of the printed resist contact area to the metal absorber mask defect area is measured under different process conditions, i.e., different exposure doses. It is found that the EUV resist contact area responds to the mask defect area linearly for small mask defects. From such a set of contact area change vs. defect area response lines, the allowable absorber mask defect requirement for the contact layer is assessed via statistical explanation of the printable mask defect size, which is tied to the wafer process specifications and the actual wafer process CD controllability. Our results showed that a clear and an opaque intrusion corner absorber mask defect as small as 70 - 80 nm (4X) is printable for 90 nm contacts when 10% contact area change (or 5% contact DC change) due to defect alone is allowed. The effect of an opaque defect at center of a contact is found similar to that of corner opaque defect for smaller defect. It becomes much worse than that of at edges when defect is large. Based on the statistical defect printability analysis method that we have developed, the printable mask defect size can always be re-defined without additional data collection when the process controllability or the process specification changes.
We present recent experimental results from an actinic (operates at the EUV wavelength) defect inspection system for extreme ultraviolet lithography mask blanks. A method to cross-register and cross-correlate between the actinic inspection system and a commercial visible-light scattering defect inspection system is demonstrated. Thus, random, real defects detected using the visible-light scattering inspection tool can be found and studied by our actinic inspection tool. Several defects with sub-100 nm size (as classified by the visible scattering tool) are found with the actinic inspection tool with a good signal to noise ratio. This result demonstrates the capability of the actinic inspection tool for independent defect counting experiments at a sub-100 nm defect sensitivity level.