How Are Microchips and CPUs Made?

Photo by Francesco Vantini on Unsplash

Have you ever wondered how the tiny brains inside our smartphones and computers are made? Let’s dive into the fascinating world of microchip and CPU manufacturing.

What You’ll Get from Reading This Article

As someone who’s spent years studying and working in the semiconductor industry, I’m excited to share the fascinating process of how microchips and CPUs are made. This article will take you on a journey through the intricate world of semiconductor fabrication, breaking down complex concepts into easy-to-understand explanations. After reading this article, you’ll have a solid grasp of:

• The scale and complexity of microchip manufacturing
• The key steps involved in creating a CPU
• The advanced tools and techniques used in semiconductor fabrication plants
• How billions of tiny transistors come together to form powerful computing devices

Let’s dive into the world of microchip manufacturing!

The Incredible Scale of Microchips

Modern technology relies heavily on microchips, and the numbers are staggering. Did you know that a typical smartphone contains about 62 microchips with a total of 90 billion transistors?

That’s more transistors than there are people on Earth!

Inside a Semiconductor Fabrication Plant

Microchips are made in massive facilities called semiconductor fabrication plants, or “fabs” for short. Here’s what you need to know about these high-tech factories:

• Size: A typical fab’s clean room is about the size of 8 football fields
• Equipment: Hundreds of machines, ranging from van-sized to bus-sized, fill the clean room
• Cost: Each machine can cost between a few million to 170 million dollars
• Production capacity: A modern fab can produce about 50,000 wafers or 11.5 million CPUs per month

Photo by Louis Reed on Unsplash

The Long Journey of Chip Manufacturing

Making a microchip is a time-consuming process:

• It takes about 3 months to complete a single-chip
• The manufacturing process involves around 1,000 steps
• Each silicon wafer travels from machine to machine, undergoing various processes.

Layers Upon Layers: The Anatomy of a CPU

Modern CPUs are incredibly complex:

• A typical CPU chip has about 80 different layers
• These layers include transistors at the bottom and multiple layers of metal wires (interconnects) above.
• The largest CPUs can contain up to 26 billion transistors

Creating a Single Layer: A Simplified Process

Here’s a basic overview of how a single layer of an integrated circuit is created:

1. Deposit insulating material (silicon dioxide) on the wafer.
2. Apply a light-sensitive coating (photoresist).
3. Use UV light and a stencil to create a pattern on the photoresist.
4. Remove exposed areas of photoresist with solvents.
5. Etch away the exposed silicon dioxide.
6. Remove the remaining photoresist.
7. Add a layer of metal (like copper).
8. Grind down and level the surface

This process is repeated many times to build all the layers of the chip.

Moving Wafers Around the Fab

Silicon wafers are transported within the fab using:

• Front Opening Universal Pods (FOUPs): sealed plastic containers that hold 25 wafers
• An overhead transport system that moves FOUPs between machines
• Robotic arms inside each machine that handle individual wafers

The Six Categories of Fab Tools

Microchip manufacturing relies on six main types of tools:

1. Mask-making tools: Create patterns on the wafer.
2. Deposition tools: Add materials to the wafer.
3. Removal tools: Etch away unwanted material.
4. Modification tools: Change material properties.
5. Cleaning tools: Remove contaminants from the wafer.
6. Inspection tools: Check for defects and ensure quality

The Magic of Photolithography

Photolithography is a crucial step in chip manufacturing:

• It uses UV light to create precise patterns on the wafer.
• A photomask (stencil) contains the design for each layer.
• The pattern is shrunk down 4 times before being printed on the wafer.
• Each CPU requires 80 different photomasks, each costing $300,000

Etching and Ion Implantation: Shaping the Chip

To remove material and modify the wafer’s properties:

• Etching tools use chemicals or plasma to remove unwanted material.
• Ion implanters shoot ions into the wafer to change its electrical properties

Keeping It Clean: Wafer Cleaning Process

Cleanliness is crucial in chip manufacturing:

• Wafers are cleaned frequently throughout the process.
• Special cleaning tools use various methods like mega sonic cleaning and chemical baths

Quality Control: Metrology Tools

To ensure everything is built correctly:

• Metrology tools inspect the wafer at various stages.
• They use techniques like electron microscopy and X-ray analysis

From Sand to Silicon: Wafer Manufacturing

Before chip production begins:

1. High-purity silicon is melted and formed into a large crystal ingot.
2. The ingot is sliced into thin wafers.
3. Wafers are polished to a mirror-like finish

After Manufacturing: Testing and Packaging

Once chips are made on the wafer:

1. Each chip is tested for functionality.
2. Working chips are cut out from the wafer.
3. Chips are categorized or “binned” based on their performance.
4. They’re packaged in protective casings with pins for connecting to circuit boards

Wrapping Up: From Fab to Your Device

The journey of a CPU from the fab to your computer involves:

1. Extensive testing and categorization.
2. Packaging in a protective casing.
3. Installation on a motherboard or circuit board.
4. Finally, it’s ready to power your favorite devices!

Making microchips and CPUs is an incredibly complex process that combines cutting-edge technology, precision engineering, and a bit of magic. The next time you use your smartphone or computer, take a moment to appreciate the billions of tiny transistors working together to make it all possible!

FAQs

How Many Microchips and Transistors Are in a Typical Smartphone?

Inside a typical smartphone, there are about 62 microchips containing a total of 90 billion transistors. These microchips are the powerhouse behind the device’s functionality

The Size and Layout of a Typical Semiconductor Fabrication Plant

A semiconductor fabrication plant, or fab, is a massive facility. The clean room alone can span the area of 8 football fields. It houses hundreds of machines, ranging in size from vans to city buses, each costing between a few million to 170 million dollars.

How Long Does It Take to Manufacture a Microchip?

Manufacturing a microchip is a lengthy process, taking around 3 months. During this time, silicon wafers travel from machine to machine, undergoing approximately 1,000 processes.

How Many Layers Are in a Typical CPU Chip?

A typical CPU chip consists of over a dozen layers of wires, with a total of 17 metal layers of wires in the CPU. These layers include local, intermediate, and global interconnects that move data around the chip

The Basic Process for Creating a Single Layer of an Integrated Circuit

1. Deposition: A layer of insulating silicon dioxide is deposited on the wafer.
2. Photoresist Application: A light-sensitive photoresist layer is spread across the wafer.
3. Exposure: UV light and a stencil (photomask) are used to create a pattern on the photoresist.
4. Development: Solvents remove the exposed areas of the photoresist, creating a mask layer.
5. Etching: The revealed silicon dioxide is etched away.
6. Metal Deposition: A layer of copper is added to fill the etched areas.
7. Planarization: The surface is ground down to level it off

How Are Silicon Wafers Transported Within a Semiconductor Fabrication Plant?

Silicon wafers are transported in stacks of 25 using a container called a Front Opening Universal Pod (FOUP). These pods are moved around the cleanroom floor via an overhead transport system, which lowers them onto the tool’s landing pad for processing

Production Capacity of the Semiconductor Fabrication Plant

A typical semiconductor fab has a production capacity of 50,000 wafers or 11.5 million CPUs per month. The cleanroom floor houses 435 semiconductor tools organized in rows to perform the same processes

Six Main Categories of Tools Used in Microchip Manufacturing

1. Mask Layer Tools: Photoresist spin coater, photolithography tool, developer, photoresist stripper.
2. Deposition Tools: Add materials like metals, insulators, and crystalline silicon.
3. Etching Tools: Remove materials using chemicals or plasmas.
4. Modification Tools: Ion implanters to modify material properties.
5. Cleaning Tools: Wash away dust and contaminants.
6. Inspection Tools: Ensure everything is built correctly

Purpose and Function of Photolithography in Microchip Manufacturing

Photolithography is crucial for creating the nanoscopic patterns on the wafer. It involves shining UV light through a photomask to transfer the design onto the photoresist layer on the wafer. This process is repeated for each layer of the chip

Cost of a Single Photomask

Each photomask used in the photolithography process costs around $300,000. A single CPU chip may require up to 80 different photomasks

Main Methods for Removing Material from a Wafer

1. bb: Uses corrosive chemicals or high-energy plasmas to remove materials.
2. Chemical Mechanical Planarization (CMP): Combines chemical and mechanical processes to smooth and level the wafer surface

Purpose of Ion Implanters in Microchip Manufacturing

Ion implanters are used to modify the electrical properties of the wafer by implanting ions into the silicon. This step is crucial for creating the transistor structures

How Are Wafers Cleaned During the Manufacturing Process?

Wafers are frequently cleaned using specialized cleaning tools to wash away dust particles and contaminants. This ensures the integrity of the microchip during the manufacturing process

Purpose of Metrology Tools in Microchip Manufacturing

Metrology tools are used to inspect and measure the wafer at various stages of the manufacturing process. They ensure that each layer is built accurately and help identify any defects

in Manufacturing a Single Metal Interconnect Layer

1. Deposition of Insulating Layer: Silicon dioxide is deposited.
2. Photoresist Application: A photoresist layer is applied.
3. Exposure and Development: UV light and photomask create a pattern.
4. Etching: Exposed areas are etched away.
5. Metal Deposition: Copper is added.
6. Planarization: The surface is leveled off

How Are Silicon Wafers Manufactured Before Chip Production Begins?

Silicon wafers are made from pure silicon extracted from sand. The silicon is melted and formed into a cylindrical ingot, which is then sliced into thin wafers. These wafers are polished to create a smooth surface for chip production

What Happens to Chips After They Are Manufactured on the Wafer?

Once the chips are manufactured on the wafer, they are cut out, tested, and packaged. This process ensures that only functional chips are used in devices

How Are CPUs Categorized or “Binned” Based on Their Functionality?

CPUs are tested and categorized based on their performance and functionality. This process, known as “binning,” ensures that CPUs meet specific performance criteria before being sold

Final Steps in Preparing a CPU for Installation in a Computer

After binning, CPUs are packaged and tested again to ensure quality. They are then prepared for installation in computers, ready to power the next generation of technology