Large-scale integration

Definition

A stage of technology and scale of design that integrates hundreds to thousands of transistors and their interconnections into a single integrated circuit.

What it is

Large-scale integration is a stage in manufacturing and design rather than a single device: the number of transistors integrated on a chip is sufficient to support complex memory arrays, arithmetic logic, and control functions. It depends on smaller features, higher yields, and more complex interconnections.

Why it emerged and what problems it solved

Small-scale and medium-scale integration still required many chips and circuit boards to form a complete system, making board-level interconnection a bottleneck for speed, size, and reliability. LSI placed more functions on the same piece of silicon, reducing external connections.

Why it matters and what it enabled

LSI gradually brought the CPU's key components from multiple boards and chips onto a single chip. It drove growth in both memory density and processor complexity, providing the fabrication capabilities needed for the microprocessor's emergence in 1971.

Principles and impact

Problems solved

Overcomes limitations of small-scale and medium-scale integration in function count and board-level interconnection.
Compresses complete memory arrays, arithmetic units, and processor subsystems into a small number of chips.

Principles

Smaller linewidths, higher yields, and multilayer interconnects allow more devices to be replicated on the same wafer.
Designers use standard cells, arrays, and layouts to map system functions into chip geometries.

Improvements

Shorter interconnections and fewer packages improve system speed and reliability.
Lowers the cost per logic function, advancing the commercialization of memory and processor chips.

Significance

Provides the fabrication and design capabilities needed to integrate the CPU's main functions onto one chip.
Made increasing device density a continuing industry objective.

History and applications

People

Gordon Moore、Federico Faggin、Robert Noyce

Organizations

Fairchild Semiconductor、Intel

Events

Moore discussed the growth of integrated-circuit complexity in 1965、LSI memory and processor chips emerged in the 1970s

Applications

High-capacity semiconductor memory、Arithmetic logic units and controllers、Early microprocessors

Limitations

Layout complexity, defect rates, test coverage requirements, and heat dissipation demands continue to grow.
Manufacturing equipment and mask costs increase with process complexity.

Upstream and downstream relations

Upstream

←Semiconductor photolithographydepends onLarge-scale integration relies on repeated photolithography, doping, oxidation, and interconnection steps to reliably shrink and reproduce device structures.

Sources: The Silicon Engine: A Timeline of Semiconductors in Computers 1959: Invention of the Planar Manufacturing Process

←Silicon-gate processdepends onThe silicon-gate MOS process increased device density and manufacturing feasibility, enabling processor logic to be consolidated into a small number of chips.

Sources: 1971: Microprocessor Integrates CPU Function onto a Single Chip 1970: MOS Dynamic RAM Competes with Magnetic Core Memory on Price

←Integrated circuitsevolved fromLarge-scale integration developed by increasing the number of devices on a single chip, incorporating more and more logic functions into one chip.

Sources: The Silicon Engine: A Timeline of Semiconductors in Computers The Silicon Engine Timeline

Downstream

→Central processing unitenablesOnce a single chip could accommodate more logic gates and registers, the main functions of a central processing unit could be condensed from circuitry spread across multiple boards onto fewer chips.

Sources: 1971: Microprocessor Integrates CPU Function onto a Single Chip

→Microprocessorrequired byA single-chip CPU requires thousands of MOS transistors to be fabricated and interconnected within a limited chip area, relying on large-scale integration capabilities.