What Is an Integrated Circuit?

Jack Kilby and Robert Noyce separately came up with the idea of placing transistors on a single piece of silicon. This unified circuitry, known as an integrated circuit or IC, made modern computers and other devices feasible.

An IC starts off as a large silicon crystal that is “salami sliced” into discs the size of compact disks, called wafers. The wafers are then etched to make the contact terminals.

IC Layout

Integrated circuits are used in all kinds of electronic devices, from watches to traffic lights and computers. They are very small and work by connecting many different components together. To make an IC, engineers use specialized software and hardware description languages to create a blueprint of how the chip will function. The resulting design is then created in a lab. Depending on the complexity of the circuit, it can take several years to complete.

The layout of an IC is determined by the physical constraints of the circuit chip chip. To ensure that the IC is manufactured correctly, it is important to understand these limitations. This includes knowing the size of individual components, how much space is available for signal paths and power distribution, and what protections are necessary to keep the IC from damage when being handled and installed.

Once the layout is finalized, it must be verified to be correct. This can be done using a tool called a layout versus schematic (LVS) check. This step compares the layout with the original circuit diagram to verify that they match. A new version of this tool has been developed for photonic ICs, which is known as photonic LVS.

The process of making a chip is very complex, and the layout design must be very carefully planned to avoid errors. These errors may be in the physics of the IC, or they may occur due to manufacturing defects.

IC Design

The design of an IC is one of the most complex engineering tasks mankind has ever accomplished. It involves generating and interconnecting billions of transistors in something smaller than a human finger to produce the desired functionality of a specific electronic chip.

The first step is the architectural or block design phase, which defines what a chip will do and how it will perform. Here, the IC designer uses human-understandable design languages to develop an overall design and to capture it in a schematic diagram. Depending on the complexity of the system, some designers may use pre-existing modules such as memories, storage, processing units or sensors to save time.

Once a schematic is finalized, the IC designer starts the logic design process. Here, the high-level description of the IC is converted into register transfer level (RTL) code using hardware description languages like VHDL and Verilog, or with the help of advanced modeling tools. RTL code describes the connections between logic gates and flip-flops, enabling the IC to perform its required functions.

The physical layout is then defined, which determines where each component will be placed on a wafer and how they will connect with each other. This is a critical step, since the placement and dimensions of each device must be precise in order to achieve the desired performance. Other important concerns include power dissipation, contact resistance and electromigration of metallic interconnects.

IC Testing

The intricately engineered ICs that power our electronics are sensitive to the slightest deviation from their intended functionality. Defective components can lead to unreliable products and costly production delays, so rigorous IC testing is vital throughout the manufacturing process.

IC testing can take place at two levels: wafer test, also known as probe test, that tests the chip directly before packaging, and package test, which tests the circuit chip manufacturer packaged IC after assembly. The tests are performed with automatic test equipment (ATE), which gives electrical signals to the semiconductor device and compares their responses to expected values.

One way to perform a basic IC testing procedure is by placing a multimeter over the IC pins and setting it to the continuity setting. This will cause the multimeter to produce a beeping sound if there is an electrical short between the pins that are touching.

The IC testing process can reveal a lot of information about how long a chip will last and what types of stress it may face. For example, accelerated life testing (ALT) examines the lifespan of an IC by increasing its temperature and voltage to simulate aging conditions. Other common IC testing methods include Highly Accelerated Temperature and Humidity Stress Test (HAST), which evaluates the reliability of an IC’s seal by increasing the temperature and humidity.

IC Packaging

ICs are delicate pieces of semiconductor material. They need protection from mechanical damage, temperature fluctuations, and moisture. They also require a connection to the rest of a circuit board in order to transfer signals, power, and control information. This connection is established through a process known as IC packaging.

The package protects the IC and ensures that its internal components are connected properly to other devices in a circuit board. It also shields the IC from environmental threats and provides mechanical support. The package houses pins or leads that facilitate electrical connections between the IC and the rest of a circuit board. This is a critical part of the IC’s function, because traces out of an IC’s package have much different electrical properties than those confined to the die.

There are many different types of IC packages, each with their own dimensions, mounting-types, and pin-counts. One of the most familiar is the dual-inline package, or DIP, a rectangular shape with two rows of pins for through-hole mounting. Other popular options include the surface-mount package, which features pins arranged in multiple rows around the package and soldered to the surface of the PCB. The smaller size and high pin density of surface-mount packages make them ideal for modern electronics.

When choosing an IC package, it’s important to consider the performance requirements of the application. Other factors that influence the selection include cost, manufacturability, and thermal management.