More on Micro-LEDs…
Mini-LEDs and their smaller cousins, Micro-LEDs have been and continue to be touted as the ‘display technology of the future’ and while research into the development and commercialization of these types of displays is still in early stages, every once and a while something comes along that we believe is noteworthy enough to lift itself out of the morass of hype and gobbledygook that surrounds pretty much everything in the highly competitive CE space. Some of this is technical, but an understanding of the technology is essential to understanding why it has the potential to be a game changer for the Micro-LED industry in particular, although we also want to note that the technology described below is just beginning to be scaled up to commercial levels, and while we believe samples are being evaluated by a number of display manufacturers, there has been no acceptance of the technology on a commercial scale.
That said, the company, Porotech (pvt) seems to have solved two particularly difficult problems that face the use of Micro-LEDs in the commercial display market. The first is that Micro-LEDs, by their very nature, are small, anywhere from 2um to 100um, or from the approximate width of a DNA molecule to the thickness of a human hair, making them difficult to produce and even more difficult to move without damage. Given that there are 8.29m pixels in a 4K full color display, with each pixel being comprised of thre (Red, green, and blue) sub-pixels, a single 4K Micro-LED display would entail the production and transfer of 24.88m Micro-LEDs. The industry has been working toward moving away from typical semiconductor pick-and-place techniques for moving Micro-LEDs from the wafers they are produced on to display substrates, but even the most sophisticated processes take time to move that many Micro-LEDs, which equates to high cost.
One factor that helps the transfer process is that both blue and green LEDs can be produced on the same wafer, speeding up the transfer process, but red Micro-LEDs are produced using a different material base, which means that whatever process is used to pull blue or green die from a wafer, has to stop and load another wafer with red Micro-LEDs in order to complete the full transfer process. Additionally, the performance of red Micro-LEDs declines more quickly than blue or green as the size of the LEDs decreases, and the necessity to produce displays with ever smaller pixels is a key part of why the display industry is looking for materials that can exceed the limits of current LCD or OLED technology, allowing the high resolution displays needed for realistic AR/VR and other displays.
P{orotech has come up with a way to allow all three Micro-LEDs to be produced on the same wafer by etching ‘pores’ in the wafer material using a relatively simple electro-chemical process that creates ‘nano-pores’ under the surface of the material on which the Micro-LEDs are produced. This allows he material to absorb the extra Indium atoms that the red Micro-LEDs normally produce which reduce its performance, giving all three colors roughly the same characteristics without a separate wafer process. As the production and transfer cost savings of being able to produce all three Micro-LEDs on one wafer is substantial and the cost of the wafer pre-processing (pore creation) is low, the concept solves both the red performance problems and lessens the cost of the Micro-LED production and transfer cycle.
By itself- the ability to form all three Micro-LED colors on the same wafer while still maintaining similar characteristics is an accomplishment, but Porotech has taken their technology further and made the process even more simple. The company has developed what it calls Dynamic Pixel Tuning, a process by which it is able to change the color of a sub-pixel by changing the driver characteristics. Therefore, in theory, three ‘generic’ sub-pixels could become red, green, or blue sub-pixels by changing the driving characteristics of each, essentially allowing the entire Micro-LED production wafer to be the same LED, making production far simpler and making the necessity of placing individual red, green, and blue sub-pixels in the correct position unnecessary.
But, while each ‘generic’ sub-pixel can now become a red, green or blue emitter, there is still the necessity to balance the color brightness given how the human eye perceives colors, just as OLED pixel patterns have more green area than red or blue, and the idea of a ‘generic’, simple to produce Micro-LED sub-pixels is key to cost reduction. It seems that Porotech has discovered that by varying another driver characteristic the brightness of each LED can be controlled, giving the system the ability to generate full color Micro-LED displays using a more easily produced single Micro-LED structure that is able to perform the same functions as three separately produced and transferred Micro-LEDs.
There is a catch, and that is the driver circuitry typically used for Micro-LEDs would have to change and would likely be more complex, but given the single Micro-LED structure being used, and the ability to create Micro-LED displays directly on TFT silicon, would allow for ultra-high resolution AR/VR displays that would be far more expensive to produce using current Micro-LED fabrication methods. Even in larger applications such as TV, the concept of a single Micro-LED structure that can create any of the three primary colors will go a long way toward lowering the cost of the technology.
While what the technology shown here promises is certainly significant, it actually serves an additional function, and one that typically has a very high cost. When Micro-LEDs are transferred from production wafers to a final substrate, they must be placed precisely to match up with the driver electronics, with the entire transfer process having to be gentle enough not to damage these very small Micro-LEDs. When looking at the number of Micro-LEDs that need to be transferred for just one 4K display (24.88m), even a five 9’s system would generate 249 non-working Micro-LED sub-pixels, a number that would render an OLED display unusable. After the transfer process is completed in a typical Micro-LED system, each sub-pixel is tested and the non-operating sub-pixels must be removed and replaced, a process that is infinitely more expensive than the transfer itself.
There are some who propose placing a 2nd blank sub-pixel next to each active one that can be used if the original pixel is found to be damaged, but that would double the number of red, green, and blue Micro-LEDs that need to be created and transferred into position for each display, also doubling the cost and TACT time. Given the ‘generic’ characteristics of the Porotech Micro-LED, the cost of such a ‘double’ system would be considerably lower both at the production level and at the transfer level, making it a more viable alternative to the ‘remove and replace’ techniques that are used today.
So, the technology that this little company has developed seems to have solved a number of issues that are plaguing the rapid commercialization of Micro-LEDs, and while the technology is just getting to the pre-scale stage, it seems to have considerable promise as to moving the world of Micro-LEDs along a bit faster than one might have thought. As with all new technology and processes, there is no guarantee that the Porotech technology can scale or actually be practical enough for move to mass production at a cost that is lower than existing Micro-LED technologies, but at least on the surface, it seems to have considerable promise and is therefore worth a continued look.
Please note we have no connection to Porotech or any of the company’s officers or staff and have not discussed this note with the company or anyone associated with Porotech in any way. We have not received compensation in regards to this note from the company or any other sponsoring party and have no financial stake in the company or any invested entities.
That said, the company, Porotech (pvt) seems to have solved two particularly difficult problems that face the use of Micro-LEDs in the commercial display market. The first is that Micro-LEDs, by their very nature, are small, anywhere from 2um to 100um, or from the approximate width of a DNA molecule to the thickness of a human hair, making them difficult to produce and even more difficult to move without damage. Given that there are 8.29m pixels in a 4K full color display, with each pixel being comprised of thre (Red, green, and blue) sub-pixels, a single 4K Micro-LED display would entail the production and transfer of 24.88m Micro-LEDs. The industry has been working toward moving away from typical semiconductor pick-and-place techniques for moving Micro-LEDs from the wafers they are produced on to display substrates, but even the most sophisticated processes take time to move that many Micro-LEDs, which equates to high cost.
One factor that helps the transfer process is that both blue and green LEDs can be produced on the same wafer, speeding up the transfer process, but red Micro-LEDs are produced using a different material base, which means that whatever process is used to pull blue or green die from a wafer, has to stop and load another wafer with red Micro-LEDs in order to complete the full transfer process. Additionally, the performance of red Micro-LEDs declines more quickly than blue or green as the size of the LEDs decreases, and the necessity to produce displays with ever smaller pixels is a key part of why the display industry is looking for materials that can exceed the limits of current LCD or OLED technology, allowing the high resolution displays needed for realistic AR/VR and other displays.
P{orotech has come up with a way to allow all three Micro-LEDs to be produced on the same wafer by etching ‘pores’ in the wafer material using a relatively simple electro-chemical process that creates ‘nano-pores’ under the surface of the material on which the Micro-LEDs are produced. This allows he material to absorb the extra Indium atoms that the red Micro-LEDs normally produce which reduce its performance, giving all three colors roughly the same characteristics without a separate wafer process. As the production and transfer cost savings of being able to produce all three Micro-LEDs on one wafer is substantial and the cost of the wafer pre-processing (pore creation) is low, the concept solves both the red performance problems and lessens the cost of the Micro-LED production and transfer cycle.
By itself- the ability to form all three Micro-LED colors on the same wafer while still maintaining similar characteristics is an accomplishment, but Porotech has taken their technology further and made the process even more simple. The company has developed what it calls Dynamic Pixel Tuning, a process by which it is able to change the color of a sub-pixel by changing the driver characteristics. Therefore, in theory, three ‘generic’ sub-pixels could become red, green, or blue sub-pixels by changing the driving characteristics of each, essentially allowing the entire Micro-LED production wafer to be the same LED, making production far simpler and making the necessity of placing individual red, green, and blue sub-pixels in the correct position unnecessary.
But, while each ‘generic’ sub-pixel can now become a red, green or blue emitter, there is still the necessity to balance the color brightness given how the human eye perceives colors, just as OLED pixel patterns have more green area than red or blue, and the idea of a ‘generic’, simple to produce Micro-LED sub-pixels is key to cost reduction. It seems that Porotech has discovered that by varying another driver characteristic the brightness of each LED can be controlled, giving the system the ability to generate full color Micro-LED displays using a more easily produced single Micro-LED structure that is able to perform the same functions as three separately produced and transferred Micro-LEDs.
There is a catch, and that is the driver circuitry typically used for Micro-LEDs would have to change and would likely be more complex, but given the single Micro-LED structure being used, and the ability to create Micro-LED displays directly on TFT silicon, would allow for ultra-high resolution AR/VR displays that would be far more expensive to produce using current Micro-LED fabrication methods. Even in larger applications such as TV, the concept of a single Micro-LED structure that can create any of the three primary colors will go a long way toward lowering the cost of the technology.
While what the technology shown here promises is certainly significant, it actually serves an additional function, and one that typically has a very high cost. When Micro-LEDs are transferred from production wafers to a final substrate, they must be placed precisely to match up with the driver electronics, with the entire transfer process having to be gentle enough not to damage these very small Micro-LEDs. When looking at the number of Micro-LEDs that need to be transferred for just one 4K display (24.88m), even a five 9’s system would generate 249 non-working Micro-LED sub-pixels, a number that would render an OLED display unusable. After the transfer process is completed in a typical Micro-LED system, each sub-pixel is tested and the non-operating sub-pixels must be removed and replaced, a process that is infinitely more expensive than the transfer itself.
There are some who propose placing a 2nd blank sub-pixel next to each active one that can be used if the original pixel is found to be damaged, but that would double the number of red, green, and blue Micro-LEDs that need to be created and transferred into position for each display, also doubling the cost and TACT time. Given the ‘generic’ characteristics of the Porotech Micro-LED, the cost of such a ‘double’ system would be considerably lower both at the production level and at the transfer level, making it a more viable alternative to the ‘remove and replace’ techniques that are used today.
So, the technology that this little company has developed seems to have solved a number of issues that are plaguing the rapid commercialization of Micro-LEDs, and while the technology is just getting to the pre-scale stage, it seems to have considerable promise as to moving the world of Micro-LEDs along a bit faster than one might have thought. As with all new technology and processes, there is no guarantee that the Porotech technology can scale or actually be practical enough for move to mass production at a cost that is lower than existing Micro-LED technologies, but at least on the surface, it seems to have considerable promise and is therefore worth a continued look.
Please note we have no connection to Porotech or any of the company’s officers or staff and have not discussed this note with the company or anyone associated with Porotech in any way. We have not received compensation in regards to this note from the company or any other sponsoring party and have no financial stake in the company or any invested entities.
Electron Microscope Image of Nanopores in LED material - Source: USPO
Various OLED sub-pixel patterns - Source: GlobalSMT.net
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