Editor's Note: There are a lot of folks who are interested in accelerating their algorithms/programs written in C or C++. Many of these guys and gals are aware that FPGA-based accelerators are available, but they don't know how you actually make these little rascals perform their magic.

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Tkool Electronics

Editor's Note: There are a lot of folks who are interested in accelerating their algorithms/programs written in C or C++. Many of these guys and gals are aware that FPGA-based accelerators are available, but they don't know how you actually make these little rascals perform their magic.

MTSW-114-27-T-S-1140_Datasheet PDF

Editor's Note: There are a lot of folks who are interested in accelerating their algorithms/programs written in C or C++. Many of these guys and gals are aware that FPGA-based accelerators are available, but they don't know how you actually make these little rascals perform their magic.

Basics of chip/package codesign in a large flipchip application

As technology migrates from 90 nm to 65 nm and, eventually, to the 45-nm node, fast yield ramp-up is increasingly difficult to achieve due to the sub-wavelength effects of lithography. While minimum feature size in IC design has decreased with each process node, the wavelength of steppers used in lithography has remained constant at 193 nm. This so-called lithography gap” makes it difficult to produce an accurate image of the reticle on the wafer, resulting in qualitative defects in the layout that lead to catastrophic or parametric yield loss. In some cases, these lithography issues contribute up to 40 percent of the overall yield loss.

MTSW-114-27-T-S-1140_Datasheet PDF

Most of these problems manifest themselves as layout-related issues that can be collectively called layout hot spots. Traditionally, designers have avoided these problems by creating comprehensive and consistent design rules. But with each new process node, this layout-related yield issue has become increasingly challenging, especially when one wants to keep the design rules simple, yet achieve maximum IC density.

At 45 nm, for instance, IC manufacturers use higher numerical aperture during exposure and far more aggressive resolution enhancement techniques (RET). These practices increase the range in which features impact printing on the wafer due to the generation of more complex interference patterns of the light during exposure. Typically, design rules are used to prevent layout patterns that cause printing problems. Because of this increased range, however, the design rules have to account for significantly larger, and therefore, more complicated patterns.

Printing-related problems, or layout-related yield issues, are most severe in irregular patterns with high density, so they require aggressive RET. Design rules, RET and process are initially developed and optimized for regular patterns like lines and spaces, then extended for more irregular patterns. However, designers cannot anticipate or test for all potential patterns. So, some situations inevitably arise that cause failures. Layout problems of this nature are most often found in the process front-end, such as layers diffusion, poly, contact and metal1, where density is crucial.

MTSW-114-27-T-S-1140_Datasheet PDF

Lithography is not the only cause of printing problems. As RET and optical proximity correction (OPC) become increasingly complicated, the setup of OPC tools may cause problems as well. Aggressive OPC in itself is model-based. But parts of the setup, such as segmentation or placement of assist features, are rule-based. As with the regular layout design rules, designers cannot anticipate all possible variations of layout patterns and leave problems in the layout. Accordingly, they end up with the wrong mask layout, resulting in systematic yield loss.

MTSW-114-27-T-S-1140_Datasheet PDF

Sources of hot spots Lithography-induced hot spots manifest themselves in the layout as defects that are best detected by analyzing for any of a variety of problems related to common yield-loss mechanisms. These problems include:

* Printability, i.e. severe variation in line width or spacing

The following main factors have an influence on accuracy of the system:

The absolute angle precision for ferrite pole wheels is typically 0.15°. Due to unsymmetrical magnetization, the pole length can vary by 1%, and assembly variations are three dimensional (axial, radial, and tangential).

However, factors which induce a change to the magnetic flow density are inconsequential because the gain control will compensate for them. But assembly tolerances, which make the sine and cosine curves unsymmetrical (e.g. an unbalance or a gradient to the parallel axis), are critical.

During soldering, the IC package could twist or be displaced. This applies also to the alloy process for the chip inside the package and is tested to be maximum ±0.2 mm to the center with a twist of ±3%. At the layout, it has to be considered that the four iC-ML Hall sensors are 0.7 mm from the chip center in longitudinal axis.

To support the different applications in a most flexible way, the iC-ML has 28 different modes of operation. They are selected through three input pins with TriState” input logic.

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