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Most people don’t give too much thought to the tiny components which form such an integral part of almost all modern communication devices, from PCs to mobile phones.
Indeed, mobile chips get almost no public recognition in a world which seems to care more about screen size, shiny aluminum casings and apps – yet without powerful application processors, our handsets and devices would be nothing more than bricks.
Making chips, however, is no easy task, nor is it a cheap one, resulting in many firms choosing to outsource their manufacturing to dedicated “fabs” to feed the almost insatiable modern appetite for smaller, faster processors.
In Singapore recently, RCR was privileged to be able to get a glimpse behind the chipmaking curtain at GlobalFoundries’ fab 7, where wafer upon wafer of chips are churned out daily from within the impressive maze of cleanrooms.
GlobalFoundries’ expertise is in producing very small, very power efficient chips based on the ARM architecture and Fab 7 manufactures mobile products for many of the world’s largest wireless chip companies including Qualcomm, Broadcom, Atheros and many others.
Getting a grand tour of the facility, VP of Fab 7 Peter Benyon explained the magic behind the process as well as the inherent paradoxes of balancing the need for increased performance with lower power and heat, larger die sizes at lower costs and how increased complexity can have a negative impact on wafer yields.
The process of making a wafer can take two to three months and involves a number of steps including film deposition (Oxidation, DCVD & PVD), chemical mechanical polishing (CMP), photolithography, etching, cleaning technology, implantation and diffusion. Each of these is a process in and of itself, and can be repeated several times in fixed order.
After the initial polishing phase, photolithography is where the actual chipmaking really begins, as the pattern is projected onto the wafer like an optical mask. That creates a pattern in the etching resist which is then exposed to light, to dissolve parts of the substrate in a process similar to the one that occurs in photography.
The next stage is Plasma Etching, in which a high-speed stream of glow discharge (plasma) gas is shot at the wafer in bursts. After a while, the atoms embed themselves at or just below the surface of the target and modify its physical properties.
After etching comes yet more cleaning before the wafer arrives at the implant phase where a controlled amount of impurities is added to the silicon structure in order to improve electrical conduction, in a process similar to shooting bullets into walls. Diffusion then drives the impurities further into the silicon structure so that the good electrical conducting area becomes bigger.
Typically, each wafer goes through 33-50 mask levels and 500- 800 processing steps and by the end, with its multiple layers and levels, wafer fabrication can be likened to building multi-level highways.
So next time you pick up your phone, you might want to marvel at the sheer amount of work and complexity that went into making its smallest, but most important, component – the processor chip.
Check out RCR’s slideshow from inside Fab 7 below:
