Steps to Successfully Create a Chip from Scratch

This article is authorized for reprint from the public account “Semiconductor Industry Observation”, ID: icbank, Author: Gong Jiajia

How many steps does it take to put an elephant in a refrigerator? Three steps: open the refrigerator door, put in the elephant, and finally close the door. So how many steps does it take to create a chip? Also three steps: design the chip, manufacture the chip, and finally package and test the chip. However, is making a chip really that simple? Obviously not. Recently, an article titled “How Long Can 100 Million Yuan Last in a Chip Startup” went viral among many people’s social circles, which included a line stating, “By the time 100 million is burned through, many companies have not even seen a glimpse of the chip, and might not even have a decent demo.”

Indeed, 100 million yuan might buy a luxury apartment, but it may not be enough to support a chip from design to mass production. This is only true for chips using mature processes; for advanced process chips, the costs are even more staggering—with the design cost for a 5nm chip reaching as high as 476 million dollars.

Today, I will explain how many steps are actually required to create a chip from scratch and why it is so “money-consuming”.

Steps to Successfully Create a Chip from Scratch

Chip Design

Many people compare the process of manufacturing a chip to constructing a building. So what is the first and most important step? Of course, it is the design blueprint of the building, which in this case is the chip. In other words, chip design is the foundation for creating a chip. Even if downstream manufacturing and testing capabilities are top-notch, without a design blueprint, it is all in vain.

As one of the most intricate and grand engineering projects in the world, chip design is definitely not as simple as drawing on a computer. Generally speaking, the chip design phase can be divided into four major processes: specification definition, system-level design, front-end design, and back-end design.

Specification Definition

Specification definition is when engineers conduct a needs analysis for the chip at the beginning of the design process, determining the cost control level, purpose, and performance of the chip, and completing the product specification definition to set the overall direction of the design. Then they check the agreements that need to be met; otherwise, the chip will not be compatible with market products and cannot connect with other devices. Finally, the implementation method of the chip is established, with different functions assigned to different units, and the connection methods between different units are defined, thus completing the specification formulation. The purpose of chip specification definition is to ensure that the designed chip has no errors.

System-Level Design

Since chip design must comprehensively consider factors such as system interaction, functionality, cost, power consumption, performance, safety, and testability, engineers need to develop design solutions and specific implementation architecture designs based on the preliminary specification definition, dividing module functions, and clarifying the chip architecture, business modules, power supply, and other system-level designs, such as CPU, GPU, NPU, RAM, connections, interfaces, etc.

Front-End Design

Front-end design of the chip, also known as logic design, can be said to be the soul of the entire chip design phase, truly realizing the process of creating a chip from nothing. Therefore, front-end design engineers are among the most sought-after talents in the industry, and their salaries naturally rise as well. Of course, this is beside the point. So what does front-end design work mainly involve?

Front-end design is when engineers carry out specific circuit designs for each module based on the system design solutions, using Verilog or VHDL code (hardware description language) to describe the specific circuit implementation at the RTL (Register Transfer Level). In simple terms, it is describing the module functions with code, which means translating the actual hardware circuit functions into HDL language to form RTL code. The code corresponds to the circuit, so front-end design engineers need to know what the circuit will look like behind the code they write.

After the code is generated, it needs to undergo simulation verification, strictly following the established specification standards, using simulation verification to repeatedly check the correctness of the code design. Verification is the most time-consuming and labor-intensive step in chip design; according to ARM’s technical white paper, 40% of a project’s resources are spent on the verification phase.

Once verification is completed, logical synthesis is required, using EDA tools to convert the register transfer level design RTL description into a netlist, ensuring that the circuit meets standards in terms of area, timing, and other target parameters. Then static timing analysis is performed, applying specific timing models to analyze whether specific circuits violate the timing constraints set by the designer.

The front-end design process is not completed in one go; engineers must repeatedly synthesize, verify, and conduct various design rule checks to ensure both the correctness of the design and the feasibility and optimization of layout and routing.

Back-End Design

Back-end design is the implementation of front-end design. Specifically, it involves converting the logic synthesis into a physical netlist and then converting it into graphic files that can be used by manufacturing plants to create photomasks.

The first step is DFT (Design For Test), which is testability design. Chips often come with built-in test circuits, which need to be pre-planned and various logic circuits for chip testing inserted.

Next is layout planning, where the placement of macro unit modules for the chip is determined, establishing the placement of various functional circuits, such as IP modules, RAM, I/O pins, etc. The chip area, timing convergence, stability, and routing difficulty will all be affected by layout planning.

Apple A11 Layout Planning

Then clock tree synthesis is performed, which is the wiring of the clock, connecting various components together. Since the clock signal plays a global commanding role in digital chips, it is symmetrically connected to each register unit, so that when the clock reaches each register from the same clock source, the clock delay difference is minimized. Therefore, it often requires separate wiring.

After clock wiring, regular signal wiring is performed, including routing between various standard cells (basic logic gate circuits); parasitic parameters are extracted, and signal integrity issues are analyzed and verified again; finally, various verifications are conducted, generating GDS layouts for chip production.

Back-end design is the last step before chip production and often faces many challenges and tight deadlines. As we enter the nanometer era, with the increasing complexity of layout and routing, its importance is becoming more pronounced. However, for some small and medium-sized design firms, having an excellent back-end design team and minimizing capital expenditure is like trying to have the best of both worlds; cultivating a complete back-end team is too expensive and can exacerbate the financial constraints, but if there is no back-end design and only front-end engineers are relied upon, the lack of project experience may lead to a lot of redundant work and even affect the final performance and power consumption of the chip. In this context, finding the best balance between the two to achieve the highest return on capital expenditure becomes crucial, and achieving this requires the support of a professional team.

In fact, many chip companies choose to outsource back-end design to chip design service companies. Yes, this introduces another layer of division of labor in the industry; chip design service companies do not belong to chip design enterprises or wafer manufacturing enterprises, but are an inevitable product of the development of the chip industry, bridging the gap between chip design companies and wafer foundries. Well-known companies like Creative Electronics, ChipSource, Moore Elite, ZhiYuan Technology, and Canxin Semiconductor all belong to this category.

Chip design service plays a role as a chip design foundry center in the chip industry chain, providing great value for chip design companies, especially for startup design firms, and their comprehensive back-end design services are one of the important values. Generally speaking, chip design service companies have rich experience in back-end design; for example, Creative Electronics, as a full-process customized IC design service company, is very professional in digital back-end (DFT, STA, APR) and can provide comprehensive DFT services. Moore Elite is a leading one-stop chip design and supply chain service platform in China, committed to “making it easy to create chips in China”; in the field of chip design services, Moore Elite provides ASIC design and turnkey solutions. Their stable back-end design team has extensive experience in SoC design and project management, providing digital back-end design aimed at advanced process nodes. Although Canxin Semiconductor’s business mainly includes IP and chip customization services, their chip customization services also cover both front-end and back-end, and their strength should not be underestimated.

As Moore’s Law continues to develop, coupled with the trends of miniaturization and integration, back-end design is becoming increasingly complex and important. Unlike those wealthy system vendors and internet companies, startup chip companies need to understand how to “carry light gear” to push chips to market with the lowest risk and cost possible.

Chip Manufacturing

Chip manufacturing is a crucial step in turning the chip from blueprint to physical product, but before mass production, there is an important step known as wafer fabrication, commonly referred to as trial production.

For chip developers, wafer fabrication is akin to an exam for students; just as students turn pale at the thought of an exam, chip developers do the same at the thought of wafer fabrication. The reason is that the cost of a failed wafer fabrication can be extremely severe; one failed wafer fabrication can often mean losses of several million or even tens of millions, as well as the loss of at least half a year’s market opportunities. Many startup chip companies have disappeared into the vastness of the chip industry due to failed wafer fabrications. The reasons for failed wafer fabrications are also varied; it could be as simple as reversing VDD and GND or using the wrong liquid for wet cleaning. In short, any small oversight could lead to a failed wafer fabrication.

Back to the point, how many steps are there in chip manufacturing, and why does it make companies “turn pale”? It is understood that a chip production line involves about 2000-5000 processes. I may not be able to cover all of them, so I will only introduce some key steps.

Broadly speaking, wafer production includes two major steps: ingot manufacturing and wafer manufacturing, along with the wafer probing process, collectively referred to as the front-end processes of wafer manufacturing. The subsequent packaging and testing will be referred to as the back-end processes of wafer manufacturing.

1. Purification: Sand/quartz is deoxygenated and purified to obtain silicon dioxide with a silicon content of 25%. It is then refined in an electric arc furnace, chlorinated with hydrochloric acid, and distilled to obtain crystalline silicon with a purity of over 99%.

2. Ingot Manufacturing: Crystalline silicon is melted at high temperatures and stretched by rotation, undergoing neck growth, crown growth, crystal growth, and tail growth to obtain a complete ingot.

3. Slicing: The ingot is cut horizontally using a thin saw blade embedded with diamond particles on the inner diameter edge to produce wafers of consistent thickness.

4. Polishing: The appearance of the wafer is polished to remove saw marks and damage caused during cutting, achieving the required smoothness of the wafer surface.

5. Oxidation: The surface undergoes oxidation and chemical vapor deposition, which serves as an auxiliary layer for later processes and helps isolate electrical devices to prevent short circuits.

6. Photolithography and Etching: A layer of photoresist is spin-coated onto the oxidized wafer surface, exposed, and then developed to reveal the circuit pattern. Chemical reactions or plasma bombardment are then used to transfer the circuit pattern onto the wafer surface.

7. Ion Implantation and Annealing: Impurity ions are bombarded into the semiconductor lattice, and the ion-implanted semiconductor is heated at a certain temperature to activate the different electrical properties of the semiconductor material.

8. Vapor Deposition and Plating: Vapor deposition is used to form various metal and insulating layers, while plating is specifically used for growing copper wiring layers.

9. Chemical Mechanical Polishing: A combination of chemical etching and mechanical polishing is used for polishing.

10. Finally, multiple layers of circuits and components are processed and manufactured on the wafer.

11. Wafer Probing Process: Each die is tested for its electrical characteristics using a probe tester, discarding any non-compliant dies.

Chip Packaging and Testing

Packaging and testing refers to the back-end processes of wafer manufacturing mentioned above, where packaging involves processing the tested wafers into chips, and testing involves checking for defective chips, including wafer testing before packaging and finished product testing.

As the last mile before chip production, packaging and testing is also a crucial step for finished chips. Packaging can protect, support, connect, dissipate heat, and ensure reliability for the chip, while testing ensures chip quality and can even enhance shipment quality, preventing defective chips from being shipped. Specifically, the packaging and testing steps can be divided into:

1. Back Thinning: The wafer is thinned on the back to reach the thickness required for packaging.

2. Wafer Cutting: The wafer is cut into individual dice, which are then cleaned.

3. Optical Inspection: Check for defects.

4. Chip Bonding: Chips are bonded, silver paste is cured (to prevent oxidation), and wire bonding is performed.

5. Molding: To prevent external impacts, the product is encapsulated with EMC (epoxy molding compound) while being heated to cure.

6. Laser Marking: The production date, batch number, and other information are engraved on the product.

7. High-Temperature Curing: Protects the internal structure of the IC and eliminates internal stress.

8. Excess Material Removal: Trimming the edges.

9. Plating: Improves conductivity and enhances solderability.

10. Inspection of sliced and molded products for defects.

11. Chip Testing: Divided into general testing and special testing; general testing checks the electrical characteristics of the chip, classifying them into different grades based on electrical characteristics. Special testing is targeted testing to see if it meets specific customer requirements.

12. Qualified products are labeled with specifications, model numbers, and production dates, packaged, and then shipped.

Final Thoughts

Chip manufacturing is indeed a money-burning industry. To truly achieve mass production of a chip, each of the steps mentioned above is crucial. For startups lacking people, money, and resources, not to mention the IDM model, even cultivating a professional team for the four major processes of chip design is challenging. As mentioned in the article “How Long Can 100 Million Yuan Last in a Chip Startup”, many founders spend their days in meetings, managing, and raising funds, and then return to the company at night to work on technology.

No startup’s success is smooth sailing; the pressures they face are unimaginable to ordinary people and are ever-changing. While twists and turns are inevitable, how to minimize detours on the road to success is controllable. The key is to find the solution that best suits one’s circumstances, which is the direction that many startup chip companies are striving for.

Editor: Six Dollar Fish

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