(Color online) Schematic drawing of effects of open area ratio at the wafer level (global: R G), chip level (semi-local: R S), and local level (ΩL).
(Color online) Layout of experimental wafers with different R G values (0.60, 0.72, 0.79, 0.86, and 0.91). Chips of open, hatched, and closed squares are covered with all poly-Si area(1), medium poly-Si area (0.72), and non poly-Si area (0).
(Color online) Layout of experimental wafers with semi-local open area and various local patterns notated from A to H. Each pattern of A, B, C, and D has 6 different spaces as expressed by arrows. Patterns of F, G, and H are surrounded by other patterns 2 μm away. The closed circle shown in each pattern was a measured point of ΔCD.
(Color online) (a) ΔCD as a function of global open area ratio R G. The solid line represents a fitting result of the least-squares method. (b) Measured taper angle of etched profiles for R G of 0.6 and 0.91. Two SEM images of etched profiles are also displayed.
(Color online) ΔCD as a function of distance from chip edge in the cases of R S of 0.71, 0.76, and 0.87. Closed circles, triangles, and squares with solid lines represent the ΔCD values for many Si shots (R S of 0.87), few Si shots (R S of 0.76), and no Si shots (R S of 0.71), respectively. P1, P2, P3, and P4 are locations of target patterns in the chip. Location of the chip edge is set to zero as a distance. Measured wafers and pattern density maps are also displayed.
(Color online) (a) ΔCD as a function of space of four different kinds of patterns in the case of R G of 0.72. (b) ΔCD dependent on solid angle viewing from a pattern in the case of R G of 0.72. The solid line represents a fitting result of the least-squares method.
(Color online) ΔCD values of patterns E, F, G, and H as notated in Fig. 3 . These values are normalized by that of pattern E.
(Color online) Integrated intensity derived from OES data (closed circle marks), which is the origin of the B2Σ+-X2π transition state of the SiBr radical. Closed square marks represent the integrated intensity in the case of a 20% increase in total flow rate.
(Color online) Schematic drawing of our flux model of etched by-product (SiBrx), considering effects of global (R G), semi-local (R S), and local (ΩL). ΓG and ΓS represent fluxes origin of R G and R S, respectively.
Flowchart of our gate etching simulation procedure.
(Color online) Schematic drawing of surface reaction and etch front evolution. S(t) and S(t + dt) represent etch front of time t and t + dt. Circle marks on the etch front are lattice points, and arrows from the points are normal vectors.
(Color online) Schematic picture of Si recess depth in the pattern. d SiBrO, d SiO2, and d R represent depths of deposition on the etched surface, gate oxide, and Si recess, respectively.
(Color online) (a) Simulation results of etched profiles (photoresist, BARC, and poly-Si) in the cases of R G of 0.40 and 0.86. (b) Simulation results of etched profiles and ΔCD in the cases of ΩL of 0.8 and 1.2. Observed etched profiles and ΔCD values are also displayed.
(Color online) Solid lines represent (a) calculated deposition depth d SiBrO and (b) Si recess depth d R as a function of (R G + R S)ΩL. Closed circles and squares represent measured values in the cases of patterns in the narrow and wide regions, respectively.
(Color online) (a) SEM images of patterns in the narrow and wide regions. (b) and (c) TEM images of interface layer (poly-Si/gate-oxide) of patterns in the narrow and wide regions. The images in (b) and (c) are in the cases of as-etched and post wet treatment, respectively. Dashed lines represent the interface layer between gate oxide and Si substrate. Measured values of deposition depth (d SiBrO) and Si recess depth (d R) are also displayed.
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