The release and scattering of photoelectrons and secondary electrons in EUV resists has often been glossed over in most studies in EUV lithography, despite being a fundamental factor in the image formation. Fortunately, Intel has provided us with a laboriously simulated electron release and scattering model, using the GEANT4… Read More
This past week we … Read More
China’s recent achievement of a 7nm-class foundry node using only DUV lithography [1] raises the question of how far DUV lithography can be extended by multipatterning. A recent publication at CSTIC 2023 indicates that Chinese groups are currently looking at extension of DUV-based multipatterning to 5nm, going so far… Read More
Extreme ultraviolet (EUV) lithography is often represented as benefiting from the 13.5 nm wavelength (actually it is a range of wavelengths, mostly ~13.2-13.8 nm), when actually it works through the action of secondary electrons, electrons released by photoelectrons which are themselves released from ionization by absorbed… Read More
With metal interconnect pitches shrinking in advanced technology nodes, the center-to-center (C2C) separations between vias are also expected to shrink. For a 5/4nm node minimum metal pitch of 28 nm, we should expect vias separated by 40 nm (Figure 1a). Projecting to 3nm, a metal pitch of 24 nm should lead us to expect vias separated… Read More
In the assessment of wafer lithography processes, normalized image log-slope (NILS) gives the % change in width for a given % change in dose [1,2]. A nominal NILS value of 2 indicates 10% change in linewidth for 10% change in dose; the % change in linewidth is inversely proportional to the NILS. In a previous article [2], it was shown… Read More
At the 2023 SPIE Advanced Lithography and Patterning conference, ASML presented an update on its EUV lithography systems in the field [1]. The EUV wafer exposure output was presented and is shown below in table form:
From this information, we can attempt to extract and assess the EUV wafer output per quarter. First, since there … Read More
Current 1a-DRAM and 5/4nm foundry nodes have minimum pitches in the 28 nm pitch range. The actual 28 nm pitch patterns are one-dimensional active area fins (for both DRAM and foundry) as well as one-dimensional lower metal lines (in the case of foundry). One can imagine that, for a two-dimensional routing pattern, both horizontal… Read More
Masks have always been an essential part of the lithography process in the semiconductor industry. With the smallest printed features already being subwavelength for both DUV and EUV cases at the bleeding edge, mask patterns play a more crucial role than ever. Moreover, in the case of EUV lithography, throughput is a concern, … Read More
The many idiosyncrasies of EUV lithography affect the resolution that can actually be realized. One which still does not get as much attention as it should is the cross-slit pupil rotation [1-3]. This is a fundamental consequence of using rotational symmetry in ring-field optical systems to control aberrations in reflective… Read More
