Navigating Pre-Silicon and Post-Silicon: Understanding Semiconductor Dynamics

To sail smoothly through the pre- and post-silicon era and grasp the dynamics of semiconductors, let's first clarify what semiconductors and silicon actually are. While many may think they're one and the same, there's a slight but important difference between the two.

Semiconductors, also known as chips or ICs (Integrated Circuits), have become quite the buzz lately, popping up in newspapers, magazines, and conversations everywhere. But the story of these semiconductor marvels begins with something as basic as sand – yes, sand, or more specifically, quartz sand, abundant and rich in silicon dioxide (SiO2). Through a series of chemical reactions, silicon is extracted from this sand, purifying it to over 99.9% in purity. This purified silicon is then doped with elements from the Boron or Phosphorous groups to precisely control its electrical properties.

But that's just the beginning. Ever heard of the CZ process? This process helps create seed crystals, known as ingots, from molten silicon. These ingots are then sliced into circular shapes to obtain bare silicon, commonly referred to as Bare-Si or Bare-wafers in industrial lingo. But let's be honest, nobody likes things to be plain and simple, right? Hence, various designs or patterns are etched onto these bare wafers to give them some flair. Processes like Photolithography, Chemical Vapor Deposition, Physical Vapor Deposition, Ion Implantation, and Etching work their magic to transform these bare wafers into the final product – a reticle printed wafer with small circuits etched onto them. And remember, the larger the wafer, the more chips can be produced from it. The goal here is to fabricate tighter and smaller designs to churn out as many dies as possible. Terms like die, chip, component, and IC are often used interchangeably in the industry.

These dies can then be packaged into components or ICs using different encapsulation materials. Now, you might be wondering, what exactly is post-silicon then? Well, everything we've discussed so far revolves around physically producing chips, which can be categorised as post-silicon processes. To ensure the quality of these chips, rigorous testing is conducted at high temperatures and voltages, putting them under considerable stress to ensure only the best materials make it to the consumer.

Terms such as early life failure rate and Bath curve play crucial roles in assessing the quality and reliability of these chips. And just to be clear, we're not discussing your regular potato chips or crisps here; we're diving into the world of ICs – Integrated Circuits, commonly known as chips.

Now, you might be wondering, why is it called the Bath curve? The term originated from the shape of the curve resembling a bathtub when plotted on a graph. This curve illustrates the failure rate of a product over time, showing a high initial failure rate (early life failure rate), followed by a period of relatively low failure rates, and then an increase in failures as the product reaches the end of its life cycle.

As for early life failure rate, it refers to the rate at which failures occur in the initial stages of a product's life cycle, typically during the first few months of operation. These failures are often attributed to manufacturing defects or issues with the design process and are crucial to address to ensure the overall reliability of the product.

As we navigate through the complexities of semiconductor technology, it becomes paramount to grasp these terms in order to effectively evaluate the quality and reliability of the chips powering our diverse array of electronic devices. Alongside, it's crucial to recognise the pivotal role of companies engaged in silicon processes. These include industry leaders such as Intel, AMD, NVIDIA, Qualcomm, and Broadcom. Some of the companies involved in post-silicon works include Micron, Global Foundries, and Samsung. Each of these companies plays a significant role in advancing silicon technologies and ensuring the quality and reliability of semiconductor products.

On the other hand, pre-silicon activities encompass everything leading up to these processes we've discussed thus far. This phase primarily involves simulation, analysis, and chip design. Electronic design automation (EDA) tools, integral to this phase, aid in designing, creating, and simulating chips. Layouts and floor planning contribute to shaping the structure of IPs within the chips. A fundamental concept in this realm is the Y chart, also known as the Gajski chart, which provides comprehensive insights into chip design methodology.

Companies engaged in pre-silicon endeavours, such as Arm, Cadence Design Systems, Synopsys, and Imagination Technologies, play a crucial role in laying the groundwork for the development and optimisation of semiconductor technology. In the UK specifically, companies like Arm Holdings and Imagination Technologies have made significant contributions to pre-silicon processes, driving innovation and pushing the boundaries of chip design.