White Papers

Semiconductor manufacturing is continuously ramping up the yield of technology processes with transistor dimensions well below the exposure wave length. Light diraction eects limit the resolution of pattern with ever smaller dimension in ArF lithography using a fixed exposure wave length of 193nm and prevent printing wafer patterns identical to the shapes drawn on the exposure mask. Resolution enhancement techniques such as Optical Proximity Correction (OPC) enable new technologies to be realized in wafer manufacturing. Sub-resolution assist features (SRAF), or scatter bars (SB), provide critical process window enhancements in the lithography process. Traditionally, SRAF generation is based on geometric rules, which are extracted from a large amount of simulation and empirical wafer data from printing test masks.

With the continuous development of today’s technology, IC design becomes a more complex process. The designer now not only takes care of the normal design and layout parameters as usual, but also needs to consider the process variation impact on the design to preserve the same chip functionality with no failure during fabrication. In the current process, schematic designers go through extensive simulations to cover all the possible variations of their design parameters and hence of the design functionality. At the same time, layout designers perform time-consuming process-aware simulations (such as lithography simulations) on the full chip layout, which impacts the design turn-around time. In this paper, we present a fast physical layout and electrical-aware Design-For-Manufacturability (DFM) solution that detects hotspot areas in the full chip design without requiring extensive electrical and process simulations. Novel algorithms are proposed to implement the engines that are used to develop this solution. Our proposed flow is examined on a 45 nm industrial Finite Impulse Response (FIR) full chip. The proposed methodology is able to define a list of electrical hotspot devices located on the FIR critical path that experience up to 17% variation in their DC current values due to the effect of process and design context. The total runtime needed to identify and detect these electrical hotspots on the FIR full chip takes nearly 3 minutes, compared to hours when using conventional electrical and process simulations.

In this work, we introduce the use of pattern matching as a potential solution for many verification flows problems. Pattern matching offers a great TAT advantage since it is a DRC based process, thus it is much faster than time consuming LITHO operations. Also, its capability to match geometries directly and operability on many layers simultaneously eliminates complex SVRF coding from our flows. Firstly, we will use the pattern matching in order not to run OPC verification on basic designs identified by the OPC engineer to be error free, which is a very useful technique especially in Memory designs and improves the run time. Then, it will be used to detect waivers, which is hard to code, while running verification flows and eliminate it from the output, and consequently the reviewer will not be distracted by it and concentrate on real errors. And finally, it will be used to detect hot spots in a separate very quick run before standard LITHO verification run which gives the designer/OPC engineer the opportunity to fix design/OPC issues without waiting for lengthy verification flows, and that in turns further improves TAT.

As IC technologies shrink and via defects remain the same size, the probability of via defects increases. Redundant via
insertion is an effective method to reduce yield loss related to via failures, but a large number of extremely complex
design rules make efficient automatic via insertion difficult. This paper introduces an automatic redundant via insertion
flow which is capable of adopting new technologies and complex design rules extremely quickly. Runtime and
efficiency are optimized through a smart insertion scheduling technique. Our experiments show that it efficiently
improves redundant via percentage, making designs more robust against via defects.

In this paper, we present a fully automated CAD solution that captures the designer’s intent from the schematic netlist, and links these annotations to the proper devices or nets on the physical layout level.

Memory designers need to increase bit density to meet exacting specifications for fast data transfer and low power consumption. Higher density increases the interactions between interconnect and devices, yet they have to design with real design margins. Accurate characterization is required at every step of memory design. Memory designers need a tool that can help them analyze parasitic issues accurately and quickly at every stage of the physical design cycle, as well as design cutting-edge memories from basic building blocks to the full chip. Using Calibre xACT 3D at all stages of memory design, from bit cell design to full chip sign-off, ensures a robust design that will work to specification when it is manufactured.