Understanding CFETs, A Next Generation Transistor Architecture


Computing power has experienced exponential growth over the last 70 years. This has largely been achieved through transistor scaling. Due to a continuous reduction in the size of transistors, engineers have been able to pack more and more of them onto a single chip [1]. This has led to faster, more powerful, and more energy-efficient devices. Improvements in fabrication processes and materials,... » read more

Exploring Process Scenarios To Improve DRAM Device Performance


In the world of advanced semiconductor fabrication, creating precise device profiles (edge shapes) is an important step in achieving targeted on-chip electrical performance. For example, saddle fin profiles in a DRAM memory device must be precisely fabricated during process development in order to avoid memory performance issues. Saddle fins were introduced in DRAM devices to increase channel l... » read more

Techniques To Identify And Correct Asymmetric Wafer Map Defects Caused By Design And Process Errors


Asymmetries in wafer map defects are usually treated as random production hardware defects. For example, asymmetric wafer defects can be caused by particles inadvertently deposited on a wafer during any number of process steps. In this article, I want to share a different mechanism that can cause wafer defects. Namely, that these defects can be structural defects that are caused by a biased dep... » read more

Analysis Of BEOL Metal Schemes By Process Modeling


The semiconductor industry has been diligently searching for alternative metal line materials to replace the conventional copper dual damascene scheme, because as interconnect dimensions shrink, the barrier accounts for an increasing fraction of the total line volume. The barrier layer's dimensions cannot be scaled down as quickly as the metal line width (figure 1). Popular barrier materials su... » read more

Improving DRAM Device Performance Through Saddle Fin Process Optimization


As DRAM technology nodes have scaled down, access transistor issues have been highlighted due to weak gate controllability. Saddle Fins with Buried Channel Array Transistors (BCAT) have subsequently been introduced to increase channel length, prevent short channel effects, and increase data retention times [1]. However, at technology nodes beyond 20nm, securing sufficient device performance (su... » read more

Impacts Of Process Flow, Scaling, And Variability On Interconnect Performance


Virtual fabrication is used to evaluate the performance of interconnects (line and via resistance, capacitance, etc.) across pitches compatible with either EUV single exposure or SADP for three different process flows: single damascene, dual damascene, and semi-damascene (subtractive metal etch). The effects of process variation for the three flows are also investigated to determine the relativ... » read more

A Comparative Evaluation Of DRAM Bit-Line Spacer Integration Schemes


With decreasing dynamic random-access memory (DRAM) cell sizes, DRAM process development has become increasingly difficult. Bit-line (BL) sensing margins and refresh times have become problematic as cell sizes have decreased, due to an increase in BL parasitic capacitance (Cb). The main factor impacting Cb is the parasitic capacitance between the BL and the node contact (CBL-NC) [1]. To reduce ... » read more

Pathfinding By Process Window Modeling: Advanced DRAM Capacitor Patterning Process Window Evaluation Using Virtual Fabrication


In advanced DRAM, capacitors with closely packed patterning are designed to increase cell density. Thus, advanced patterning schemes, such as multiple litho-etch, SADP and SAQP processes may be needed. In this paper, we systematically evaluate a DRAM capacitor hole formation process that includes SADP and SAQP patterning, using virtual fabrication and statistical analysis in SEMulator3D. The pu... » read more

Creating Airgaps To Reduce Parasitic Capacitance In FEOL


Reducing the parasitic capacitance between the gate metal and the source/drain contact of a transistor can decrease device switching delays. One way to reduce parasitic capacitance is to reduce the effective dielectric constant of the material layers between the gate and source/drain. This can be done by creating airgaps in the dielectric material at that location. This type of work has been do... » read more

Insights Into Advanced DRAM Capacitor Patterning: Process Window Evaluation Using Virtual Fabrication


With continuous device scaling, process windows have become narrower and narrower due to smaller feature sizes and greater process step variability [1]. A key task during the R&D stage of semiconductor development is to choose a good integration scheme with a relatively large process window. When wafer test data is limited, evaluating the process window for different integration schemes can... » read more

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