Integrated Circuits and Microprocessors Quiz

The ability of electrons to pass through an extremely thin barrier, even without enough energy to overcome it.

A thin layer of material that electrically isolates the gate electrode from the channel in a MOSFET. It prevents unwanted current flow and allows for control over the channel.

A measure of the ability of a material to store an electric field, affecting the thickness of the insulator needed to prevent electron tunneling.

A type of transistor used in integrated circuits, operating by controlling the flow of electrons through a channel with an electric field applied to a gate electrode.

A material used as a gate electrode in MOSFETs. It's heavily doped to reduce resistance, providing control over the threshold voltage.

The minimum voltage required to turn on the channel in a MOSFET. It is controlled by the doping type and concentration of the gate electrode.

A layer of SiO2 used as a buffer between the Si substrate and the alternative gate insulator in a MOSFET. This minimizes the detrimental effects of the alternative material on the performance.

The use of metal electrodes in MOSFETs instead of Polysilicon. It simplifies fabrication by eliminating the need for separate metals for nMOSFETs and pMOSFETs.

The ability to define features on a chip, depending on factors like wavelength of light, mask resolution, resist material, processing steps, and manufacturing tolerance.

Electromagnetic radiation with a wavelength similar to or greater than the minimum feature size is crucial for avoiding diffraction. This ensures the image is sharp and not blurry.

A material that is sensitive to light and can be used to transfer a pattern from a mask to a semiconductor wafer.

The process of using light to create patterns on a semiconductor wafer.

A device that uses light to create patterns on a semiconductor wafer.

A measure of the ability of a lens to focus light, determining how small a feature can be resolved. It's calculated as NA = nsinθ, where n is the refractive index of the medium and θ is the half-angle of light.

The minimum feature size that can be defined by a stepper, calculated as CD = kλ / NA.

A parameter that reflects the process conditions and influences the minimum feature size.

The transistor effect was discovered in 1947, but it took nearly 24 years to create a true digital revolution with the introduction of the first microprocessor in 1971.

The first commercial microprocessor, the Intel 4004, was introduced in 1971. This landmark chip contained 2300 transistors, employed a 10µm technology using NMOS, and ran at a clock speed of 740 KHz.

The number of transistors on a chip doubles roughly every two years, leading to a significant increase in processing power over time.

Clock speed, a key indicator of processor performance, roughly doubles every three years.

Scaling refers to the shrinking of feature sizes on a chip. Smaller features allow more transistors to be placed on the same area, leading to increased density.

The scaling rate is the ratio of the size of a feature in one generation to the size of the same feature in the previous generation. A scaling factor of 1.2/year means that the sizes of features shrink by 20% each year.

The scaling factor (s) impacts the scaling of both transistor density and clock speed. A scaling factor of 1.2 leads to a doubling of transistors every two years and a doubling of clock speed every three years. This trend is evident in the history of Intel microprocessor development from 1971 to 2002.

While the scaling factor of 1.2/year was targeted by companies like Intel, it's important to note that these were marketing claims. Technological limitations and other factors influence the actual practical achievements.

The ability of a manufacturer to produce a specific integrated circuit (IC) is influenced by multiple factors, including technological advancements, design considerations, cost, profitability, marketing strategy, competition, and risk.

The progression of microprocessors is driven by improvements in performance, while the advancement of memory is focused on increasing storage density.

Memory technology, specifically Dynamic Random Access Memory (DRAM), has consistently evolved over decades, with density increasing at the expense of speed to accommodate growing storage demands.

To maintain balance in computing systems, efforts have been made to address the increasing gap between processor speed and memory speed. Techniques include caching, synchronous memories, and wider data buses.

Computer performance is dependent on both the processing power of the microprocessor and the speed of data transfer between the microprocessor and memory.

A type of transistor commonly used in integrated circuits. It controls the flow of electrons through a channel using an electric field applied to a gate electrode.

The shrinking rate of transistors in integrated circuits has slowed down, with current technology nearing the limit of 22nm. This is due to challenges in scaling down transistor sizes, leading to increased leakage currents and difficulty in controlling heat generation.

High-end processors are predicted to have around 1.5 billion transistors, with examples like the Intel Core i7 processor from 2012 reaching 1.4 billion transistors. This demonstrates the significant progress in transistor density within integrated circuits.

The prediction for clock frequencies to reach 20GHz has proven incorrect. Scaling processor frequencies beyond 4GHz is challenging due to power consumption and heat dissipation issues. The industry has focused on other methods like increasing core counts and parallelism to enhance performance.

DRAM (Dynamic Random Access Memory) is expected to reach a density of 12 gigabits per square centimeter, but currently, leading-edge devices achieve around 4.5 gigabits per square centimeter. This indicates a gap between envisioned and actual performance within the memory technology.

The transition from aluminum (Al) to copper (Cu) within integrated circuit interconnects improves conductivity, reducing resistance and enhancing signal speed. However, challenges include Cu migration into silicon at the boundary, requiring careful design and fabrication techniques.

The use of dielectrics with lower relative permittivity (εr) helps reduce capacitance in interconnects, improving signal speed. Conversely, materials with higher εr are used to maintain gate thicknesses within manageable limits, addressing challenges associated with scaling down transistors.

Silicon-on-Insulator (SOI) technology is becoming increasingly popular due to its superior characteristics like reduced parasitics, improved performance, and lower power consumption. However, the cost difference compared to traditional silicon-based technologies remains a barrier to widespread adoption.

FinFETs (Fin Field-Effect Transistors) have been introduced by Intel at 22nm to address challenges associated with transistor scaling. These transistors exhibit improved performance and lower leakage currents compared to traditional planar transistors, paving the way for future advancements in shrinking technologies.