Predicting process windows for pattern density multiplication using block copolymer directed self-assembly in conjunction with chemoepitaxial guiding layers

Effect of chemoepitaxial guiding underlayer design on the pattern quality and shape of aligned lamellae for fabrication of line-space patterns

“…In Figure 6B, the line widths for a preferential background region and a pinning stripe of width W pin /L 0 = 0.5 are shown (left middle simulation in Figure 5). This is likely close to the optimal process conditions for aligning a BCP film 12 and decreasing LER (Figure 3), however, it can be seen that in this case there is still some footing of the pinned line, even with a pinning stripe that is commensurate with the natural width of the line. Finally, in Figure 6C, it can be seen that an oversized pinning stripe with a preferential background region (bottom left simulation in Figure 5) causes greatly increased footing of the pinned line.…”

“…However it should also be noted that this underlayer has a small pinning stripe and a nearly neutral composition, which means this underlayer is virtually unpatterned and will therefore not have enough guiding power to align the BCP film from a mixed state. Figure 10B shows the width profile for a background composition near what should be the ideal composition, as determined elsewhere, 12 and has a pinning stripe width that is more reasonable than Figure 10A, placing this combination within the process window determined previously. 12 It can be seen that the pinned line does not appear to have much footing or other variation, however, the unpinned line does undercut due to the preferential underlayer.…”

“…Figure 10B shows the width profile for a background composition near what should be the ideal composition, as determined elsewhere, 12 and has a pinning stripe width that is more reasonable than Figure 10A, placing this combination within the process window determined previously. 12 It can be seen that the pinned line does not appear to have much footing or other variation, however, the unpinned line does undercut due to the preferential underlayer. It can be seen that the variations in the unpinned line, both the undercutting near the base of the line as well as the subsequent swelling near z = 5 nm, have an effect on the pinned line, though the effect appears to be relatively small.…”

“…These underlayers are typically composed of a repeating pattern of a thin stripe known as a "pinning" stripe, which is approximately the width of one half the domain and is highly preferential to one block of the BCP, followed by a "background" region, which is typically the width of some odd integer number of half domains and is more neutral to both blocks of the BCP, though it has been shown that the best alignment of the BCP film to the underlayer occurs when this background region is more preferential to the block of the BCP that is not pinned by the pinning stripe. 10,12,13 Once the BCP is properly aligned to the underlayer, one block of the BCP can be removed and the remaining block can be used as a mask in subsequent etching, deposition, or doping steps. It is important that the lamellae that formed be as straight as possible along the length of the line, as both LER and LWR adversely affect performance.…”