Negative tone development (NTD) process benefits the process latitude of dark field features such as contact holes and isolated trenches. Thus the NTD process has been a viable manufacture solution for aggressive-pitch contact patterning. Because the NTD process adopts organic solvent as developer to dissolve the de-protected photo-resist, it may conflict with conventional positive tone development on maximizing the photocell utilization. In the manufacturing implementation of NTD process, the off-line development is the most commonly adopted arrangement to maximize the flexibility of photocell dispatch. Therefore the post exposure bake to development delay (PEBDD) is a concern for thorough investigation to deliver robust NTD process. In this paper, PEBDD induced CD shrinkage was investigated for contact printing to explore the possible mechanism. The resist comparison, ambient contamination verification, baking temperature split of photo-resists were conducted for comparing the PEBDD effect. The experimental results suggested the photo acid concentration and photo acid diffusion are two most critical factors for PEBDD effect. Through the understanding of critical factors for PEBDD, the suitable operation on mitigating PEBDD influence as well as adequate queue time setting were proposed for robust process control.
SAS (Self-Aligned Source) process has been widely adopted on manufacturing NOR Flash devices. To form the SAS
structure, the compromise between small space patterning and sufficiently removing photo resist residue in topographical
substrate has been a critical challenge as the device scaling down.
In this study, photo simulation, layout optimization, resist processing and tri-layer materials were evaluated to form
defect-free and highly extendible SAS structure for NOR Flash devices. Photo simulation suggested more coherent light
source allowed the incident light to reach the trench bottom that facilitates the removal of photo resist. Mask bias also
benefited the process latitude extension for residue-free SAS printing. In the photo resist processing, both lowering the
SB (Soft Bake) and raising PEB (Post-Exposure Bake) temperature of photo resist were helpful to broaden the process
window but the final pattern profile was not good enough. Thermal flow for pos-exposure pattern shrinkage achieved
small CD (Critical Dimension) patterning with residue-free, however the materials loading effect is another issue to be
addressed at memory array boundary. Tri-layer scheme demonstrated good results in terms of free from residue, better
substrate reflectivity control, enabling smaller space printing to loosen overlay specification and minimizing the poly
gate clipping defect. It was finally proposed to combine with etch effort to from the SAS structure. Besides it is also
promising to extend to even smaller technology nodes.
Adaptive group-of-picture (GOP) structure is an important encoding tool in multi-level motion-compensated temporal filtering coding scheme. Compared to conventional fixed-GOP scheme, it can dynamically adapt the GOP size to enhance the coding performance based on each sequence's characteristics. But the existing adaptive GOP structure (AGS) algorithm proposed in JSVM requires huge computation complexity. In this paper, a fast AGS prediction algorithm is proposed. At first, based on the relationship among coding performance, GOP size and corresponding intra block ratio, a sub-GOP size prediction model for different decomposition levels is developed based on the encoded intra block ratio. Then, a prediction scheme is proposed to implement AGS by the sub-GOP size prediction model. It can predict the following sub-GOP size by current sub-GOP's information instead of searching all possible sub-GOP composition. The experimental results show that the proposed algorithm with linear threshold has almost equivalent coding performance as AGS in JSVM but only one-fourth computation complexity for 4-level interframe coding scheme is required.