iPad Pro with OLED may be more expensive because of dry etching

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Apple is rumored to bring OLED displays to the iPad Pro by 2024, manufactured using a technique called dry etching to ensure the screens remain as thin as possible. Unfortunately, this will also likely make these iPads more expensive. Here's why.

Silicon wafer. Photo by Laura Ockel on Unsplash
Silicon wafer. Photo by Laura Ockel on Unsplash


If the report about OLED iPad Pro models is taken at face value it could mean that Samsung will be a manufacturer responsible for producing the displays. The company did supply OLED panels for the iPhone 12 and iPhone 13. However, the report provided no sources other than saying "Apple confirms."

Dry etching is not new. The U.S. Patent Office granted a patent to Samsung in 2004 for a dry etching apparatus.

The patent describes a vacuum chamber where the etching takes place, a "chuck" that holds the substrate, and another part called a "baffle plate" that encloses the chuck and discharges the products used for etching. Whether Samsung still uses this particular apparatus is unknown, but vacuum chambers are necessary during the dry etching process due to the plasma.

Types of etching

Samsung describes wet etching as cheap, fast, and simple. Dry etching wafers is more precise and less prone to contamination but is expensive and complex. Thus, if Samsung uses this method for producing OLED screens, it may increase the iPad's price.

Etching is a process that removes unwanted material from a wafer, which is also known as a "slice" or "substrate." Wafers are made of semiconducting material such as crystalline silicon and are used in the fabrication of integrated circuits and solar cells.

Dry etching uses gaseous chemicals or plasmas to remove materials from a wafer, while wet etching uses liquid chemicals, such as solvents and acids. Both methods have benefits and downsides.

Wet etching

A wafer is submerged in certain chemicals during wet etching, depending on its material. For example, buffered hydrofluoric acid is commonly used with silicon wafers.

Like any manufacturing process, there are waste streams. Hydroflouric acid and the materials dissolved in the run-off from manufacturing must be appropriately disposed of to prevent water contamination. In addition, the solvent may remove more material from the wafer than is ideal.

Comparing wet etching and dry etching
Comparing wet etching and dry etching


In Samsung's chart, "Etching beneath PR" found under wet etching refers to the photoresist, a material sensitive to light that changes its properties during photo lithography. The result is intricate circuits on the thin film transistor (TFT) that the display itself is applied to.

Samsung and other manufacturers use wet etching for Apple's existing OLED supply for the iPhone.

Dry etching

A manufacturing alternative is dry etching, which is more precise and can remove substrate materials in different shapes than wet etching.

Dry etching is commonly used in very large scale integration (VLSI) processes that produce integrated circuits. There are a few methods in dry etching, such as isotropic radial etching, reactive ion etching, sputter etching, and ion milling. The intricacies of each are beyond the scope of this article, and differ based on how the process removes semiconductor materials from the wafer.

All variants of dry etching processes use plasma, which is why dry etching is often referred to as plasma etching. Ion milling and sputter etching use a beam of ions to eject or vaporize material physically.

Samsung's article describes plasma etching, where gas is injected into the vacuum chamber containing the wafers and energized to become plasma. Then, ions that gain high kinetic energy are beamed onto the wafer to remove semiconductor material.

A wafer and its circuitry before, during, and after etching
A wafer and its circuitry before, during, and after etching


In both types of etching, the photoresist acts as a protective film for the circuit pattern during the etching process. After etching, only layers coated with PR to be used as the circuit are left on the glass substrate. All other materials are removed.

Manufacturing

While dry etching isn't strictly new, it's not used in much at present.

In 2021, Gerald Yin, chairman of Chinese semiconductor equipment company AMEC, said the company's plasma etching equipment was being used in a customer's 5nm chip production.

AMEC didn't reveal the customer, but at the time the only ones capable of 5nm mass production were TSMC and Samsung, two companies that have served as manufacturers for Apple. In June 2022, TSMC posted a job listing for a "Dry Etching Process Engineering Manager" at its 5nm fab in Arizona.

Samsung's patent says that a dry etching apparatus using plasma is suitable for fabricating circuits with a width of 0.15 micrometers or less. The company concludes that dry etching is the preferred method for high-resolution displays.

The Apple supply chain will likely keep using the wet etching process for iPhone and Apple Watch. It's a cheaper solution that produces a display still lighter than an LED screen with a higher quality, at a relatively low price.

Dry etching is better products with large OLED displays. The process costs more but its precision is beneficial for these large displays where weight is a factor.

Read on AppleInsider

Comments

  • Reply 1 of 10
    thttht Posts: 5,709member
    Oh... sounds like the timing may work out here. I plan on getting an M2 iPP12.9 when it comes out, hopefully this Fall, and by the time I'm ready to replace it in 2027, an iPad with an OLED built on a mature fab will be available. Woo!
    watto_cobra
  • Reply 2 of 10
    That bad Samsung that only copies and does not innovate... right. Now will be providing (again) display panels to Apple based on it's innovative and patented OLED technology. But it is evil again as it makes devices more expensive.
  • Reply 3 of 10
    Dave CummingsDave Cummings Posts: 45unconfirmed, member
    If by dry etching, it means that it gives the glass a type of texture like on the Wacom Cintiq Pro displays with the etched glass, I'm all for it.  I'd love to have texture to the screen without a screen protector
  • Reply 4 of 10
    Mike WuertheleMike Wuerthele Posts: 6,930administrator
    If by dry etching, it means that it gives the glass a type of texture like on the Wacom Cintiq Pro displays with the etched glass, I'm all for it.  I'd love to have texture to the screen without a screen protector
    That's not what it means. What dry etching is is addressed in the piece.
    watto_cobraiOSDevSWEgatorguy
  • Reply 5 of 10
    Dave CummingsDave Cummings Posts: 45unconfirmed, member
    If by dry etching, it means that it gives the glass a type of texture like on the Wacom Cintiq Pro displays with the etched glass, I'm all for it.  I'd love to have texture to the screen without a screen protector
    That's not what it means. What dry etching is is addressed in the piece.
    Oh I know, I was just saying. I love a textured screen for drawing...but I also don't like how screens like Paperlike dull things slightly.
  • Reply 6 of 10
    bloggerblogbloggerblog Posts: 2,525member
    That bad Samsung that only copies and does not innovate... right. Now will be providing (again) display panels to Apple based on it's innovative and patented OLED technology. But it is evil again as it makes devices more expensive.
    Samsung is known to have a war chest of patents, they apply to more patents than any other manufacturer, at least in the few articles that I read. They are also known for being a high-quality component manufacturer, it is the main reason Apple has been a customer for theirs since the Apple II. However, at one point when Apple finally hit a homer with the iPhone and iPad, Samsung decided to do evil and shamelessly ape them regardless of any patents or consequences. Yet Samsung expects others to abide by patent laws and will throw their weight around to protect them.
    watto_cobraFileMakerFeller
  • Reply 7 of 10
    entropysentropys Posts: 4,313member
    More expensive? The great softening for bad news continued.
  • Reply 8 of 10
    JP234 said:
    This stuff is way, way, way beyond my limited ability to comprehend. And it's obvious that no one posting on this forum can understand the tech either.

    Well I do :) I’ve been a DRIE (Deep Reactive Ion Etching) process engineer for more than 10 years before changing completely my career and become an iOS developer. So I can tell you how amazed I was about reading about my field in this article where most of it is actually correct. An error is the sentence “While dry etching isn't strictly new, it's not used in much at present.” You would not have accelerometers or gyroscopes or sensitive pressure sensors without MEMS produced with DRIE (a sort of dry etching). Hence no Nintendo Switch, no funny games on the iPhone or IPad and so on. So what a mistake to say that dry etching is not used so much these days. The patent at the origin of it is called the Bosch process and it is from the 90’s! Airbags in cars have existed for decades thanks to dry etching!
    And if you play again one of the keynotes where Apple was presenting Deep Trench Isolation (DTI) in order to avoid having pixels bleed into another it is using dry etching. So all of you are using components made with dry etching in the gadget you are currently holding 😃.

    If you have questions about dry etching or working in a clean room making MEMS, just ask me, I’d be happy to explain.
    More articles like this! Thanks 🙏 

    PS: I’ve worked for Applied Materials Inc and have several patents on the design of DRIE chambers for MEMS. 
    lordjohnwhorfinJapheymattinoz
  • Reply 9 of 10
    bloggerblogbloggerblog Posts: 2,525member
    JP234 said:
    This stuff is way, way, way beyond my limited ability to comprehend. And it's obvious that no one posting on this forum can understand the tech either. Best to just focus on the results when the iPad Pro with this display debuts. Go to the store, pick it up, play with it, see its responsiveness, brightness, contrast, fidelity and such, and then look at the price tag to make your decision. The technology behind it is meaningless to consumers.

    Does make on wonder about the potential durability of the display. Best to buy AppleCare, no matter the cost (My wife dropped her 256GB 2019 iPad, shattered the screen, and the brand new replacement cost $49 (plus tax), instead of the $749 we paid for it!
    Btw you don't have to buy an entire new iPad if you shatter the screen. A repair kit from iFixit is like $60 depending on the iPad. But if you're not into to fixing stuff then AppleCare is a convenient option
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