Enhancing Ordering Dynamics in Solvent-Annealed Block Copolymer Films by Lithographic Hard Mask Supports

Abstract

We studied solvent-driven ordering dynamics of block copolymer films supported by a densely cross-linked polymer network designed as organic hard mask (HM) for lithographic fabrications.The ordering of microphase separated domains at low degrees of swelling corresponding to intermediate/strong segregation regimes was found to proceed significantly faster in films on a HM layer as compared to similar block copolymer films on silicon wafers. The ten-fold enhancement of the chain mobility was evident in the dynamics of morphological phase transitions and of related process of terrace-formation on a macroscale, as well as in the degree of long-range lateral order of nanostructures. The effect is independent of the chemical structure and on the volume composition (cylinder-/ lamella-forming) of the block copolymers. In-situ ellipsometric measurements of the swelling behavior revealed a cumulative increase in 1-3 vol.2 % in solvent up-take by HM-block copolymer bilayer films, so that we suggest other than dilution effect reasons for the observed significant enhancement of the chain mobility in concentrated block copolymer solutions. Another beneficial effect of the HM-support is the suppression of the film dewetting which holds true even for low molecular weight homopolymer polystyrene films at high degrees of swelling. Apart from immediate technological impact in block copolymer-assisted nanolithography, our findings convey novel insight into effects of molecular architecture on polymer-solvent interactions.

Directed self-assembly of block copolymer films on atomically-thin graphene chemical patterns

“…3e,f . In order to achieve such abrupt features using other types of chemical patterns, homopolymer/block copolymer blends are typically required to fill the gaps near the areas where the block copolymer domains bend 10 38 .…”

Simulation methods for solvent vapor annealing of block copolymer thin films

“…Solvent vapor annealing (SVA) has become a leading processing method in producing long range ordered structures in thin film block copolymer (BCP) systems. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] SVA is particularly important for BCPs with high Flory-Huggins interaction parameter w, [1][2][3][6][7][8][9][10][19][20][21][22][23][24][25][26][27][28] which are of interest for making microdomain patterns with small period but which have high order-disorder transition (ODT) temperatures requiring high annealing temperatures. SVA also enables access to non-bulk morphologies such as spheres or lamellae formed from a bulk-cylindrical BCP.…”

Reversible Switching of Block Copolymer Nanopatterns by Orthogonal Electric Fields

“…The polymer under investigation comprises a polystyrene block and a poly(2‐vinyl pyridine) block with volume fractions of 56% and 44%, respectively, a total molecular weight of M n = 99 kg mol −1 and a polydispersity of 1.05, further denoted PS‐ b ‐P2VP. Its morphology and thickness dependent swelling behavior in selective and nonselective solvents, as well as behavior under an applied electric field has been studied in detail earlier. Approximately 40 nm thick films have been spin coated from solutions in toluene (a selective solvent for the PS block), resulting in a micellar morphology.…”

“…Approximately 40 nm thick films have been spin coated from solutions in toluene (a selective solvent for the PS block), resulting in a micellar morphology. This value of the starting dry film thickness ensures that upon swelling in toluene the swollen film thickness does not exceed a critical thickness h cr of ≈75 nm (1.5 times the lamella domain spacing L 0 ) which is a condition for the in‐plane PS‐ b ‐P2VP lamella orientation under asymmetric wetting conditions . Annealed films with a thickness below h cr form a striped pattern of vertically oriented lamellae.…”