Switching‐Modulated Phase Change Memory Realized by Si‐Containing Block Copolymers

Abstract

writing current is required due to the high melting point (≈888 K @ Ge 2 Sb 2 Te 5 , GST) of the phase-switching active material. [9] In general, the writing current is highly dependent on the pattern size, contact area between active layer and heater, and material composition of active thin film, bottom electrode contact, and top electrode (TE). [10] In particular, the switching or writing current of a PCM cell scales with the phasechanging volume from the crystalline to the amorphous state in a phase-change material. [2,11] However, the scaling down of PCM arrays to reduce the power consumption for PCM cell operation is becoming more difficult due to the physical diffraction limitation of photolithography. [12] Hence, to achieve low power operation of a PCM device, many memory-research groups have studied the development of new phase-change materials and have attempted to design innovative device structures. [13][14][15] Nanopatterning refers to a process to fabricate periodic nanoscale structures with sub-100 nm feature sizes applicable to various electronic devices with complex nanoscale circuit designs. [16][17][18][19][20][21] Over the last several decades, as an advanced nanopatterning method, the self-assembly of block copolymers (BCPs) has attracted much attention due to its ultrafine pattern resolution, excellent scalability, morphological tunability, and reliable compatibility with conventional semiconducting processes. [22][23][24][25][26][27][28][29][30] BCPs can self-assemble into the various nanoscale morphologies though the microphase separation process and/or minimization of Gibbs free energy. [31][32][33] In particular, di-BCP with a high Flory-Huggins interaction parameter (χ) consisting of two immiscible polymer blocks can produce well-ordered pattern geometries with a range of 10-50 nm through the nanoscale phase-separation phenomenon. [34][35][36] Many BCP research groups have reported various advanced BCP nanopatterning methods that can be used to manipulate the pattern geometry, morphological tunability, pattern scalability, and functionality of BCPs with a high χ value. [31,[37][38][39][40] We have also demonstrated how effectively to obtain a variety of functional BCP nanostructures over a large area, such as dot, line, hole, and dot-in-hole patterns. [32,41,42] Other, BCP groups have demonstrated several electronic device applications of self-assembled functional BCPs, such as resistive memory, magnetic storage device, and PCM. [43][44][45][46][47] Although innovative BCP-based PCM studies focusing on low power consumption exist, more practical and effective strategies are still needed to realize the smart The phase change memory (PCM) is one of the key enabling memory technologies for next-generation non-volatile memory device applications due to its high writing speed, excellent endurance, long retention time, and good scalability. However, the high power consumption of PCM devices caused by the high switching current from a high resistive state to a low resistive state is a critical ...

Emerging low-cost, large-scale photonic platforms with soft lithography and self-assembly

“…Si-containing BCPs are self-assembled by a solvothermal vapor annealing process that uses annealing to enhance the rate of self-assembly [Fig. 12(c), i] [268] . Depending on the shape of the BCP structure, different resistance–current curves are observed [Fig.…”

Recent developments of block copolymers in nonvolatile memory and artificial synapses

“…Polydimethylsiloxane (PDMS) and poly(ferrocenyl dimethylsilane) (PFS) based BCPs are widely developed to construct nanopatterns for PCM applications. 26,27 The chemical structures of the insulating, core-shell type, and all-conjugated BCPs are summarized in Figure 2; while the chemical structures of the conjugated/insulating BCPs are presented in Figure 3. multiple advantages, such as excellent reliability, highspeed operation, and great scalability.…”

“…[32][33][34] In the past few decades, various BCP nanopatterning approaches have been reported, and different BCP nanostructures have been demonstrated in PCM to improve device performance. 26,27,35,36 Accordingly, low power consumption is realized by introducing BCP self-assemblies to PCM devices, which effectively reduces the contact area between the phase change material and the heating layer.…”

“…Reproduced with permission. 27 Copyright 2021, Wiley-VCH. region where the SiO x nanostructures did not exist.…”

“…Park et al developed PCM devices using two self-assembly SiO x and/or SiFe x O y nanostructures, which are depicted in Figure 5D. 27 The intensities of the writing current and reset current of a PCM are highly dependent on the contact area between GST and TiN. Since low current is preferred for low-power operation, reducing the contact area is an effective way to develop high performance PCM; and this can be realized by incorporating insulating selfassembled nanostructures, which decreases the contact area and hence decreases the current path.…”