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This paper presents a scan architecture-California scan-that achieves high quality and low power testing by modifying test patterns in the test application process. The architecture is feasible because most of the bits in the test patterns generated by ATPG tools are don't-care bits. Scan shift-in patterns have their don't-care bits assigned using the repeat-fill technique, reducing switching activity during the scan shift-in operation; the scan shift-in patterns are altered to toggle-fill patterns when they are applied to the combinational logic, improving defect coverage.

When a test set size is larger than desired, some patterns must be dropped. This paper presents a systematic method to reduce test set size; the method reorders a test set using the gate exhaustive test metric and truncates the test set to the desired size.To determine the effectiveness of the method, test sets with 1,556 test patterns were applied to 140 defective Stanford ELF18 test cores. The original test set required 758 test patterns to detect all defective cores, while the test set reordered using the presented method required 286 test patterns. The method also reduces the test application time for defective cores.

Photoresist dry etching processes by a down-stream type ECR plasma etcher were characterized. The etched photoresist profile and etch rates were obtained by scanning electron microscope (SEM) photographs and an optical thickness monitoring instrument, respectively. The mask used for PR etch tests has 1 urn pitched line & space patterns. It was found that C12 addition to 02 plasma can passivate PR side walls. The etch profiles of PR vary critically with the main coil current changes. The etch rate has maximum of 4800 A/mm and the etch uniformity has a minimum value of 5.4 %.The dc bias voltage (Vdc) variations are closely related to the etch profiles. Vdc decreases when PR etching is completed and substrates are exposed to the plasma. The wafers with different thin film materials induce different Vdc for a same process condition. The plasma properties were measured by a Langmuir probe. The N2 addition to 02 plasma were also tested. However, the critical effect of the main coil current was not found for the N2 processes. A model was formulated to explain the difference between Cl2 processes and N2 processes with an equivalent circuit method.