Mask data volume: historical perspective and future requirements

In this paper, we develop a novel fracturing algorithm with shot overlap that is tailored towards rectilinear masks, such as those generated via edge based OPC software. Our proposed fracturing algorithm generates both the location and dosage of shots given the mask layout and mask making parameters. In the first step we heuristically cover the mask polygon with overlapping shots. Next, we incorporate the forward scattering and resist model in a least squares problem to compute the best dosage for all shots. Finally, we update the locations of the shot edges by computing the edge placement error between our simulated contour and the desired contour. One unique feature of our algorithm is that it can readily trade off between edge placement error and shot count by adjusting two input parameters. Compared to a commercially available non-overlapping shot software package, for a 400µm × 400µm micron SRAM unit with about 1 million polygons, our algorithm results in a 23% reduction in shot count, while increasing the weighted average EPE from 0.7 to 1 nanometers.

Section: Mask Manufacturing Qualitymentioning

confidence: 99%

Section: Model Based Fracturingmentioning

confidence: 99%

Shot overlap model-based fracturing for edge-based OPC layouts

Jiang

Zakhor

2014

“…They need to manipulate huge file sizes which are having a significant impact on the fracturing time, tool throughput, and total productivity. In addition they need to handle the inspect-ability issues resulting from the close proximity of features and the presence of an excessive number of nubs and notches in the data [14]. All these have a big impact on the overall cost the masks and throughput.…”

Section: Introductionmentioning

confidence: 97%

Mask-friendly OPC for a reduced mask cost and writing time

Yehia

2007

In this work, the reduction of the shot count of the mask data is studied. This shot count reduction is achieved by reducing of the number of jogs resulting from the Model-Based Optical Proximity Correction (MBOPC) stage. To reduce the number of OPC-jogs, we study the impact of aligning very small jogs on the shot count as well as their effect on the residual Edge Placement Error (EPE). The OPC-jog alignment phase is made during OPC and not after it, so that the post alignment OPC iterations are responsible for the correction of any residual average EPE resulting from the jogs alignment. The results of this approach show a reduction of the total shot count in the mask fabrication stage by 18%, while the EPE distribution is still almost the same compared to the standard OPC approach, promising for a nice enhancement in the OPC flow to be more fracture friendly expected to decrease the data size of the fracturing, the mask writing time as well as the mask costs.

“…C. Spence et al have demonstrated that the number of shots is directly correlated with the write-time [4]. Furthermore, due to the small critical feature size, it is reasonable to assume that the shot count is equal to the number of post-fracture figures, namely the resulting trapezoids.…”

Section: Introductionmentioning

confidence: 99%

“…To have good critical dimension uniformity the cumulative length of external slivers should be minimized. 4. In order to minimize the shot count and hence writing time, the resulting number of trapezoids should be minimized.…”

Section: Introductionmentioning

confidence: 99%

A recursive cost-based approach to fracturing

Jiang

Zakhor

2011

In microlithography, mask patterns are first fractured into trapezoids and then fabricated with a variable shaped beam writing machine. The efficiency and quality of the writing process is determined by the trapezoid count and external slivers. Slivers are trapezoids with width less than , a parameter determined by the mask-writing tool. External slivers are slivers whose length is along the boundary of the polygon. External slivers have a large impact on critical dimension (CD) variability and should be avoided. The shrinking CD, increasing polygon density, and increasing use of resolution enhancement techniques have raised new challenges to control the trapezoid number and external sliver length. In this paper, we propose a recursive cost-based algorithm for fracturing which takes into account external sliver length as well as trapezoid count. We start by defining the notion of Cartesian convexity for rectilinear polygons.We then generate a grid-based sampling as a representation for fracturing. From these two ideas we develop two recursive algorithms; the first one utilizes a natural recurrence while the second one utilizes a more complex recurrence. Under Cartesian convexity conditions, the second algorithm is shown to provide optimal solutions; however, it has a drastically increased runtime as compared with the natural recurrence. Our simulations demonstrate the natural recurrence algorithm to produce significantly less sliver length than a commercially available fracturing tool by up to 60% in terms of external sliver length without increasing the polygon count.