CMOS Processing and Well Isolation

A type of well structure in CMOS fabrication that uses a lower surface doping and a higher doping just below the surface. It is typically formed by implanting heavy ions like Indium for p-wells and Antimony or Arsenic for n-wells.

The process of forming a gate electrode in CMOS transistors, typically using polysilicon. This involves steps like gate oxide growth, polysilicon deposition, lithography, etching, and annealing.

A technique used in CMOS fabrication where a low doped region is formed at the source and drain junctions to reduce the electric field and prevent hot carrier generation.

A type of gate oxide used in modern CMOS transistors, typically with a high dielectric constant (high-k) material like Al2O3 or HfO2, deposited using atomic layer deposition (ALD).

The process of fabricating a shallow, highly doped region near the source and drain junctions in a CMOS transistor. It involves ion implantation and annealing steps.

A process step in S/D junction fabrication that involves forming a spacer by depositing and etching thin nitride and oxide layers.

A type of ion implantation used to create a highly doped region at the source and drain junctions. This step forms the active channel between the terminals.

The undesirable phenomenon in CMOS transistors where a parasitic path exists between the power supply and the ground, potentially leading to uncontrolled current flow.

A process used to reduce the resistance of the source/drain (S/D) and poly gate in CMOS transistors.

A type of silicidation process where the metal layer is self-aligned to the S/D and poly gate using spacers.

A type of metal deposition for silicidation that creates a silicide layer during annealing.

A high-temperature process that converts silicon and the deposited metal into silicide.

The layer deposited on top of the pre-metal dielectric to planarize the surface before metal deposition.

A process used to remove the top layer of a material, making the surface smooth and flat.

Holes etched in the pre-metal dielectric to connect contacts to the underlying layers.

The process of ensuring flatness and uniformity in the metal layers of a CMOS chip, crucial for preventing short circuits and improving performance.

Shallow Trench Isolation (STI) is a technique used to isolate different regions within a CMOS chip by creating deep trenches filled with dielectric material (oxide). These trenches act as barriers to prevent electrical current from flowing between the regions.

STI is used in newer CMOS technologies (below 250nm nodes) due to its superior performance compared to LOCOS (Local Oxidation of Silicon). STI offers better isolation with shallower trenches, resulting in improved device performance.

Well formation in CMOS involves creating doped regions (p-well and n-well) within the silicon wafer. This step is essential for defining different types of transistors (PMOS and NMOS) within the circuit.

Well engineering refers to the specific doping profile and characteristics of the p-well and n-well regions. This involves controlling the depth, doping concentration, and shape of the wells for improved device performance and reliability.

A uniformly doped well is a simpler approach to well formation, where the well is uniformly doped throughout its depth. This is a common technique in older CMOS technologies.

In modern CMOS processing, well doping often involves a series of implantations to achieve a specific and complex doping profile. This allows for better control and optimization of the transistor characteristics.

In some CMOS processes, well formation might occur before the well insulation (LOCOS or STI) is implemented. This can depend on specific process requirements and design considerations.

Reactive Ion Etching (RIE) is a plasma-based etching technique used in microelectronics fabrication to etch patterns and features on silicon wafers. It uses a chemically reactive plasma to selectively remove material, creating precise shapes.

A process that deposits a thin layer of material onto a substrate, using a physical vapor deposition technique, to create a barrier resistant to diffusion and promotes adhesion.

A technique used to deposit tungsten onto a substrate, optimizing for void-free filling of holes. Tungsten is preferred due to its low resistivity which enhances signal transmission.

A technique used to remove material from a substrate, stopping at a specific layer, leaving a defined feature.

An advanced microelectronic technology used to create metal interconnects in CMOS devices, offering high density and conductivity.

The first step in the Damascene process, involving the deposition of a dielectric material, followed by a hardmask layer.

An essential step in the Damascene process that prevents copper diffusion into the surrounding materials.

A dual Damascene process involves creating two different features simultaneously: vias (vertical connections) and metal lines. This allows for complex multi-layer structures.

In the dual Damascene process, a dielectric layer is deposited to provide insulation and define the space for the via and metal features.

A fabrication method used for creating multiple layers of metal and via structures in integrated circuits. It involves etching and filling features through a hardmask layer, resulting in both metal lines and vias.

A layer of conductive material deposited to prevent diffusion of copper into the underlying layers during subsequent processing steps.

A thin layer of copper deposited onto a substrate before electroless plating, serving as a foundation for the subsequent copper deposition.

The final stage of the chip fabrication process, where the chip is passivated and equipped with bondpads to facilitate external connections.