How Sapphire, The Nearly Scratch-Proof Material Now Being Used For Smartphones, Is Made

SapphireScreenshot/GT AdvancedA sapphire wafer, from which a nearly scratch-proof sapphire display is made.

There’s been a lot of buzz around sapphire, an extremely hard material that smartphone makers are using to produce scratch-proof screen displays. Huawei, the world’s third largest smartphone maker, unveiled the Ascend P7 with a sapphire display on Friday. The announcement follows rumours that Apple’s upcoming iPhone 6 will incorporate the nearly indestructible material, although there are some major doubts.

Many are familiar with the blue sapphire gemstone, which is found in nature. But the sapphire crystal used in smartphone screens is made in a lab. It’s transparent because it doesn’t have the impurities that give mined gemstones their colour.

So how exactly is this “miracle material” made?

For a better understanding, we turn to GT Advanced Technologies, a company that sells the equipment that allows smartphone makers to produce sapphire display screens and which Apple partnered with last year.

A video byPocketnow from inside the GT Advanced Technology factory in Massachusetts provides a great demonstration of how sapphire crystal is made. The full video is embedded below, and we’ve also broken down the steps using screenshots.

Stage One: Manufacturing Sapphire Crystal 

The process starts inside these furnaces, where extreme heat and pressure turn aluminium oxide into the sapphire crystal. 

According to the Pocketnow video, a “sapphire seed,” which is about the size of a hockey puck, is placed at the bottom of a metal barrel, called a crucible.

According to the video, the seed is mixed with form of aluminium oxide and uncrystalized sapphire material, called crackle, which is shown below.

Next, the crucible is placed inside the furnace. The temperature is churned up to nearly 4,000 degrees Fahrenheit, enabling the materials to melt together. The melted material is then put through a series of cooling cycles over a period of roughly two weeks, during which time the sapphire crystallizes.

What you’re left with is a cylindrical piece of sapphire, called a sapphire boule.

The sapphire boules can then be drilled and cut to be used for a variety of purposes, including LEDs and aeroplane windows.

To make a smartphone display, however, a smaller cube is cut from the boules. This is called a sapphire wafer, from which paper-thin sheets of sapphire are made for smartphone displays.

In the next stage, described in the second part of this post, the sapphire wafer must be separated into paper-thin sheets that can be used for smartphone screens.

You can watch the full Pocketnow video below for a more in-depth look at the process.

Stage 2: Making The Sapphire Display

GT Advanced has produced their own video describing how the super-thin sheets are made using their technology.

First, the sapphire wafer is bombarded with high-energy protons (hydrogen ions) in a process called proton induced exfoliation (PIE).

To carry out this process, the GT Advanced uses its ion implantation machine, named Hyperion 4. Hydrogen ion beams hit the sapphire wafer with such a high velocity they they penetrate beneath the surface. 

The hydrogen ions form a line of hydrogen gas microbubbles underneath the wafer’s surface. Next, the wafer gets cooked.

The high heat separates super-thin sapphire sheets from the sapphire wafer. The process is repeated many times until the wafer is used up and there are a bunch of very thin sheets. 

Eventually we end up with something like this:

Sapphire screenScreenshot/PocketnowSapphire mobile phone screen

Watch a video of how this advanced technology works below.

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