sputtering technology |
| The Process |
| "Sputtering" is a vacuum process used to deposit very thin films on substrates for a wide variety of commercial and scientific purposes. |
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| It is performed by applying a high voltage across a low-pressure gas (usually argon at about 5 millitorr) to create a "plasma," which consists of electrons and gas ions in a high-energy state. (This is sometimes called a "glow discharge" process because the plasma emits a colorful halo of light.) |
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| During sputtering, energized plasma ions strike a "target", composed of the desired coating material, and cause atoms from that target to be ejected with enough energy to travel to, and bond with, the substrate. (see Figure 1.) |
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Figure 1 (click photo for larger image) |
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| Controlling Atoms |
| The process of "sputtering" has come a long way since it was first used to silver the backs of mirrors in the late 19th century. |
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| Of course, even then, scientists recognized it as a superior method of applying thin films. But the problem has always been control. Without a way to direct the flow of atoms in the process, sputtering just wasn't practical for mass production. |
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| Exploring Alternatives |
| As a result, early use of metal sputtering gave way for a time to vacuum evaporation, which employs resistive or e-beam heating, because its deposition rates were higher. |
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| But vacuum evaporation proved inappropriate for depositing materials such as insulators, and for use with substrates that have a low melting point, such as plastics - because the heat radiated from the source and carried by the atoms of the deposited material was simply too high. |
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| Introducing The Magnetron |
| Fortunately, continuing research on the sputtering process finally solved the problem, with the introduction of the planar magnetron in the 1960s. |
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| This technology uses powerful magnets to confine the "glow discharge" plasma to the region closest to the target plate. That vastly improves the deposition rate by maintaining a higher density of ions, which makes the electron/gas molecule collision process much more efficient. A schematic diagram of a magnetron is shown in Figure 2. |
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Figure 2 (click on photo for larger image) |
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| Applying Sophisticated Controls |
| Now, thanks to the increasingly sophisticated magnetic controls that have been developed over the past 30 years, sputtering has become one of the fastest-growing techniques in modern manufacturing. |
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| Adding New Value |
| In fact, today's technologists are using it to coat more surfaces in more industries than ever before. From semiconductors to credit cards; from compact discs to auto parts; from tools, packaging, and optics to medical and dental applications; magnetron sputtering is adding new value to a growing list of products every day. Because this process provides a unique combination of advantages that others just can't equal. |
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| Building A Strong And Versatile Bond |
| First and foremost, magnetron sputtering creates one of the thinnest, most uniform, most cost-effective films possible. (And it builds a virtually unbreakable bond between that film and its substrate, because it locks them together at the molecular level.) |
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| Second, it offers much greater versatility than other approaches because, as a cold momentum-transfer process, it can be used to apply either conductive or insulating materials to any type of substrate - including metals, ceramics, and heat-sensitive plastics. |
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| And third, recent advances in magnetron sputtering (see The Angstrom Advantage) now provide even more control over the application process - greater control than any other method of thin-film deposition. |
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| So, now that they have the right tools, today's researchers and engineers are using this technique to create a whole new generation of smaller, lighter, more durable products - products that are not only revolutionizing our industries, but our lives as well. |
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Angstrom Sciences |
Profiled Magnets |
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Other Magnetrons |
Ordinary Magnets |
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[click drawings to enlarge] |
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