{"id":2273,"date":"2021-04-20T07:45:45","date_gmt":"2021-04-20T14:45:45","guid":{"rendered":"https:\/\/arkelectronics.com\/digital-heroes\/?p=2273"},"modified":"2025-05-13T02:38:06","modified_gmt":"2025-05-13T09:38:06","slug":"silicon-photonics-bottlenecks-of-moores-law","status":"publish","type":"post","link":"https:\/\/arkelectronics.com\/zh-hans\/silicon-photonics-bottlenecks-of-moores-law\/","title":{"rendered":"Silicon Photonics May Remedy the Interconnect Bottlenecks of Moore\u2019s Law"},"content":{"rendered":"
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Could silicon photonics shape future technologies?<\/h2>\n

A recent article presented a new option in the challenging system bottleneck. This is an issue that has been creating roadblocks to the EMS industry over the last decade.<\/p>\n

For years, industry experts are in constant debate on exactly when Moore’s law will cease to apply. Microprocessor architects report that semiconductor advancement has slowed industry-wide since around 2010, below the pace predicted by Moore’s law. However, as of 2018, leading semiconductor manufacturers have developed IC fabrication processes\u00a0in mass production which are claimed to keep pace with Moore’s law.<\/p>\n

Moore’s law<\/b>\u00a0is the observation that\u00a0the number\u00a0of\u00a0transistors<\/a>\u00a0in a dense\u00a0integrated circuit<\/a>\u00a0(IC) doubles about every two years. Moore’s law is an\u00a0observation\u00a0and\u00a0projection\u00a0of a historical trend. Rather than a\u00a0law of physics, it is an\u00a0empirical relationship\u00a0linked to\u00a0gains from experience\u00a0in production.<\/p>\n

Many research facilities and organizations try to find a way to fight the limits that today’s computers have. First memristor and now silicon photonics may lead the way to evolution, bringing a new era with multiple capabilities and options. The processing speeds could get to the next level and AI, IoT, VR, AR can use that extra boost and shape the future. This article was initially published on allaboutcircuits.<\/a><\/p>\n

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As interconnects become an increasingly challenging system bottleneck, some researchers\u2014and even larger corporations like Intel\u2014believe silicon photonics to be a light at the end of the tunnel.<\/h3>\n<\/div>\n
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Some analysts claim that Moore\u2019s Law\u00a0is coming to a screeching halt with the arrival\u00a0of 3nm<\/a>. Most of the time this conversation centers around problems with quantum effects in scaled-down devices; however, another (and arguably more significant) problem is the interconnect, which is increasingly becoming a system bottleneck.<\/div>\n<\/div>\n<\/div>\n
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A less-discussed scaling trend is that of the interconnect. Image used courtesy of Stanford University<\/figcaption><\/figure>\n

The combined need for device improvement beyond Moore\u2019s Law, along with the diminishing functionality of traditional interconnect schemes, are paving way for the field of silicon photonics. While this field isn’t necessarily new, it is gaining traction. In December 2020, Intel\u00a0discussed at its annual “Lab Days,” that the company is actively\u00a0researching\u00a0silicon photonics “to overcome the limits of electrical I\/O<\/a>\u00a0by advancing the integration of optical and silicon technologies for future data centers and networks connected by light.”<\/p>\n

In this article, we\u2019ll discuss challenges with conventional ICs, the need for silicon photonics, and highlight recent research in which scientists used silicon photonics to create an improved ultrasound sensor.<\/p>\n

The Interconnect Bottleneck<\/h3>\n

There are two overall trends happening in the IC world currently: devices are getting smaller and chip areas are getting bigger (due to increased integration). The result of these trends is that\u00a0the interconnect, not the device, is actually becoming one of the biggest bottlenecks in IC design<\/a>.<\/p>\n

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Interconnects on an IC are directly affected by their geometry and position near one another. Image used courtesy of Stanford University<\/figcaption><\/figure>\n

Interconnects, in general, are being forced into smaller geometries\u00a0with decreased width and thickness\u00a0while global interconnects, like the clock line, are also becoming longer to accommodate larger chip sizes.<\/p>\n

Additionally, increased integration is creating more metal layers that are closer to one another. All of this results in\u00a0hugely increased interconnect impedances, where parasitic resistances, capacitances, and inductances are becoming more prominent than that of the transistors themselves<\/a>.<\/p>\n

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The interconnect is becoming an IC design bottleneck. Image used courtesy of Grzela et al.<\/figcaption><\/figure>\n

As such, the interconnect is one of the largest contributors to\u00a0both system delay and\u00a0power consumption in the form of data movement energy.<\/p>\n

Silicon Photonics: A Possible Solution<\/h3>\n

The solution to these problems, as many believe, is\u00a0silicon photonics<\/a>.<\/p>\n

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Silicon photonics use light for communication. Image used courtesy of Luxtera and IEEE Spectrum<\/figcaption><\/figure>\n

Silicon photonics is a form of IC where photonic integrated circuits are built on silicon. In these circuits, data is transmitted and moved around the chip via light through waveguides as opposed to electrical signals through copper interconnects. The result is a technique that side-steps the increasing concern of the interconnect bottleneck, creating\u00a0faster ICs without having to scale down the transistor.<\/p>\n

The technology has been mostly confined to research to this point, but there is a strong push to eventually bring it to the industry for speed and power-hungry use cases like data centers.<\/p>\n

Ultrasound Sensor Based on Silicon Photonics<\/h3>\n

Proving the value of silicon photonics, a group of researchers from the Interuniversity Microelectronics Center (IMEC) in Europe has\u00a0developed a silicon photonics-based ultrasound sensor<\/a>.<\/p>\n

Conventional ultrasound sensors use arrays of piezoelectric devices that\u00a0rely on mechanical resonance at specific ultrasound frequencies. Unfortunately, these techniques are limited by many factors. For instance, the smaller the piezo, the less sensitive it is, hindering its ability to be built into large arrays.<\/p>\n

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Ultrasound sensor layout. Image used courtesy of Westerveld et al.<\/figcaption><\/figure>\n

In their article in\u00a0Nature<\/em>,\u00a0the researchers propose a new method that\u00a0uses a \u201csplit-rib\u201d silicon photonic waveguide<\/a>. The system consists of a main part placed on a movable membrane along with a fixed rib on a substrate. The two are placed in a 15nm-wide gap containing a strong electric field.<\/p>\n

When an ultrasound wave distorts the membrane, the electric field will greatly vary the waveguide\u2019s refractive index, which will change the resonance properties of the fixed rib. The researchers were able to use tunable lasers to read out this wavelength, producing an accurate signal.<\/p>\n

The Power of Light<\/h3>\n

The ultrasound sensor proposed in this research is said to have a sensitivity 100 times\u00a0greater than conventional sensors, showing the power that silicon photonics can offer.\u00a0As Moore\u2019s Law comes to an end and interconnects become increasingly difficult to work with, a switch to silicon photonics may be just the solution to keep the field advancing.<\/p>\n

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Sources:<\/p>\n