The prospects for hierarchical data processing with growing complexity of the post-tapeout flow

Abstract

The drive of the semiconductor industry towards smaller and smaller features sizes requires more sophisticated correction methods to guarantee the final tolerances for the etched features in both wafer manufacturing and mask making. The wavelength gap in lithography and process effects as well as dependencies on the design content have led to the tremendous variety of resolution enhancement techniques and process correction approaches that are currently applied to a design on its path to manufacturing. As the 65nm nodes become production ready and the 45nm node shifts into the focus of the development effects like flare in wafer exposure, fogging effects in ebeam mask exposure and others that previously could be ignored are becoming significant so that their correction prior to manufacturing is required. That means additional correction steps are necessary to complete the data preparation. These put a larger burden on the data processing path and raise concerns over data volume and processing time limitations. Hierarchical processing methods have proven very effective in the past to keep data volumes and processing time in control. The paper explores the design trends and the potential of hierarchical processing under the new circumstances. Extended data flows with a variety of correction steps are investigated. Experimental results that demonstrate the benefit of hierarchical methods in conjunction with parallel processing methods like multithreading and distributed processing are provided. The benefit of introducing more effective data formats like OASIS in these flows will be illustrated.Historically the completion of a design was marked by the full chip verification and the delivery of a DRC an LVS clean layout. The transition of the data in form of GDSII into the mask writer format was usually a simple two step process -application of a general process bias (combination of mask and wafer lithography) and fracturing/formatting. The implementation of this simple flow was frequently shifted from the mask supplier side to the data supplier side since it was not very demanding [1]. A common flow as it is encountered today looks quite different. Figure 1 gives an example of a typical sequence as encountered in 90nm or 65nm data flows. The complexity is largely driven by the variety of processing effects that require data correction -CMP and etch processes drive the need for leveling pattern density via fill or slotting. These structures are printable elements and are inserted into the layout as part of the preprocessing prior to corrections for the imaging. A next step is rules based data corrections. This includes the insertion of non-printable assist-features for process window improvement for isolated features as well as other rules based corrections like a table driven OPC or target correction. Alternately, a phase shifting mask set can be derived to print the design pattern. After the contents of the layout are fully defined the model based OPC is applied. This functional block is followed by verification ste...

Pattern based mask process correction: impact on data quality and mask writing time

“…The impact of long range corrections on the hierarchy of a layout was described previously and will not be discussed in detail here. [6] Table 2 illustrates the effect based on the ratio of hierarchical and flat shape counts. If the area boundary would be applied via a simple "AND" operation between the area marker shape and the original layout, many shapes would be arbitrarily cut even if they were small as in the case of contactsfor example along the shaded area as illustrated in figure 5.…”

“…Flat/hierarchical shape count ratios for example data sets (post OPC) prior and post the application of a long range correction step (LRC) (tile size 100um, Sigma value 250um)[6] Illustration of the soft boundary concepts for boundary treatment.Shot Count Dependency on Soft Boundary Width (DRAM design)…”

Experimental prototype of a system to measure size and distribution of droplets in organic compound fogging on glass substrates

“…Both aspects of fogging usually need a detailed characterization of drop size, shape, and density of deposition in addition to its chemical composition. Besides the great practical interest in the electron-beam fogging effect in microelectronic manufacturing 1 and advanced microlithography technologies, [2][3][4] there are other important industrial and medical applications that need a characterization of fogging.…”