Pattern Modification Method Research Articles

Chip-scale pattern modification method for equalizing residual layer thickness in nanoimprint lithography

A software program for modifying a mold design to obtain a uniform residual layer thickness (RLT) distribution has been developed and its validity was verified by UV-nanoimprint lithography (UV-NIL) simulation. First, the effects of granularity (G) on both residual layer uniformity and filling characteristics were characterized. For a constant complementary pattern depth and a granularity that was sufficiently larger than the minimum pattern width, filling time decreased with the decrease in granularity. For a pattern design with a wide density range and an irregular distribution, the choice of a small granularity was not always a good strategy since the etching depth required for a complementary pattern occasionally exceptionally increased with the decrease in granularity. On basis of the results obtained, the automated method was applied to a chip-scale pattern modification. Simulation results showed a marked improvement in residual layer thickness uniformity for a capacity-equalized (CE) mold. For the given conditions, the standard deviation of RLT decreased in the range from 1/3 to 1/5 in accordance with pattern designs.

NIM-X: A Noise Index Model-Based X-Filling Technique to Overcome the Power Supply Switching Noise Effects on Path Delay Test

Power supply noise (PSN) has become a critical issue during high-quality at-speed testing. Discrepancies between the circuit's switching activity during functional and test mode can cause overtesting and lead to yield loss. Alternatively, reduced PSN effects around critical paths can result in undertesting the chip, causing test escapes. To achieve a high-quality at-speed test, it is necessary to solve these problems simultaneously. Our previous work introduced a noise index model (NIM), which can be used to predict the mismatch between expected and real path delays. This paper quantitatively investigates and compares NIM values for critical paths during functional and test mode. We then propose a test pattern modification method that harnesses the NIM. The method fills a subset of the don't care bits in partially specified test vectors such that the worst observed functional NIM for the targeted critical path is replicated during test mode.

Biped Landing Pattern Modification Method and Walking Experiments in Outdoor Environment

Many researchers have studied walking stability control for biped robots, most of which involve highly precise acceleration controls based on robot model mechanics. Modeling error, however, makes the control algorithms used difficult to apply to biped walking robots intended to transport human users. The “landing pattern modification method” we propose is based on nonlinear admittance control. Theoretical compliance displacement calculated from walking patterns is compared to actual compliance displacement, when a robot's foot contacts slightly uneven terrain. Terrain height is detected and the preset walking pattern is modified accordingly. The new biped foot we also propose forms larger support polygons on uneven terrain than conventional biped foot systems do. Combining our new modification method and foot, a human-carrying biped robot can traverse uneven terrain, as confirmed in walking experiments.

着地軌道修正制御と推定姿勢補償制御による人間搭乗型２足歩行ロボットの屋外歩行の実現

Many researchers have been studying on walking control methods for biped robots. However, the effectiveness of these control methods was not verified in outdoor environments such as pedestrian roads and gravel roads. In this paper, a landing pattern modification method adaptable to uneven terrain in a real environment is proposed which is based on a predictive attitude compensation control and a nonlinear compliance control. This method does not require any other sensors except force sensors. Also, a new biped foot system is described, which can form larger support polygons on uneven terrain than conventional biped foot systems. Using the pattern modification method and the foot system, WL-16R11 (Waseda Leg - No. 16 Refined II) achieved a stable walk on bumpy terrain with 20 mm height and 10 degrees inclination. Furthermore, a stable dynamic walk was realized in outdoor environment, when a human rode it. Through various walking experiments, the effectiveness of the method is confirmed.