Info
Info
News Article

Laytec Gen3 Tools Solve UV LED Challenges

Application examples demonstrate new generation of EpiTT and EpiCurve TT families 

LayTec has published a series of application examples for its 3rd generation of EpiTT and EpiCurve TT families Gen3 showing how they solve problems of epitaxial growth for UV LEDs. 

These challenges can be significant including long runs, superlattices, high Al content versus high doping level, very high growth temperature and large wafer bow and more.

One application example shows how the latest generation of tools help to overcome the wafer-showerhead gap variation in UV LED epitaxy. 

For UV LED processes, EpiTT Gen3 can measure temperatures up to 1500degC. However, for accurate temperature sensing a new Gen3 feature is also of importance: two types of metrology heads can now be chosen depending on the specific reactor conditions: the well known fibre-optical heads (FOHs) and the new parallel-beam heads (PBHs).

According to Laytec, EpiTT with PBHs is the tool of choice e.g. for Close Coupled Showerhead (CCS) reactors, where the wafer-showerhead gap is adjusted to avoid pre-reactions and achieve high growth rates in UV LED processes.

Fig. 1: Reflectance (950 nm) and temperature data during variation of gap size: a) Fibre optic head shows a reflectance drop of ~30 percent with respective temperature drop of several Kelvins depending on sample structure b)  New parallel beam head delivers a stable reflectance and temperature signal. At the standard gap distance (11 mm), both heads measure the same reflectance. (Data measured with an AbsoluT thermal reference.)

Figure 1a  (above) shows that FOHs suffer from the off-focus situation resulting from such adjustment, while PBHs in figure 1b give a very stable reflection and temperature signal under gap variation and, therefore, do not need a rather complex and time-consuming multi-gap calibration.

Accurate temperature for pss and double-side polished sapphire in UV LED epitaxy

For UV LEDs, the emitted light usually exits the device structure through the sapphire substrate. Therefore, double-side polished (dsp) sapphire is frequently used. In addition, the front surface of the sapphire substrate can be modified by nano-patterned sapphire substrates (pss) for enhanced light extraction. Both substrate specifics often cause unrecognized artifacts in temperature sensing. 

As an example, the two figures below how a temperature step run with three different types of sapphire substrates: dsp, pss and ssp (single side polished).

Conventional IR pyrometry (figure a) measures three different pocket temperatures for these wafer types. While the dsp sapphire substrate at 900degC gives the correct value, ssp is ~10K and pss is ~25K less than dsp. The level of the apparent (but not real) temperature reduction depends on temperature and on the details of back-side roughening, pss patterning and the reactor configuration. 

According to Laytec, EpiTT Gen3, however, comes with new software algorithms that take these specific effects into account and deliver the same accurate pocket temperature for ssp, dsp and pss sapphire substrates (figure b).

Further examples can be found on Laytec's website.



AngelTech Live III: Join us on 12 April 2021!

AngelTech Live III will be broadcast on 12 April 2021, 10am BST, rebroadcast on 14 April (10am CTT) and 16 April (10am PST) and will feature online versions of the market-leading physical events: CS International and PIC International PLUS a brand new Silicon Semiconductor International Track!

Thanks to the great diversity of the semiconductor industry, we are always chasing new markets and developing a range of exciting technologies.

2021 is no different. Over the last few months interest in deep-UV LEDs has rocketed, due to its capability to disinfect and sanitise areas and combat Covid-19. We shall consider a roadmap for this device, along with technologies for boosting its output.

We shall also look at microLEDs, a display with many wonderful attributes, identifying processes for handling the mass transfer of tiny emitters that hold the key to commercialisation of this technology.

We shall also discuss electrification of transportation, underpinned by wide bandgap power electronics and supported by blue lasers that are ideal for processing copper.

Additional areas we will cover include the development of GaN ICs, to improve the reach of power electronics; the great strides that have been made with gallium oxide; and a look at new materials, such as cubic GaN and AlScN.

Having attracted 1500 delegates over the last 2 online summits, the 3rd event promises to be even bigger and better – with 3 interactive sessions over 1 day and will once again prove to be a key event across the semiconductor and photonic integrated circuits calendar.

So make sure you sign up today and discover the latest cutting edge developments across the compound semiconductor and integrated photonics value chain.

REGISTER FOR FREE

VIEW SESSIONS

Info
×
Search the news archive

To close this popup you can press escape or click the close icon.
×
Logo
×
Register - Step 1

You may choose to subscribe to the Compound Semiconductor Magazine, the Compound Semiconductor Newsletter, or both. You may also request additional information if required, before submitting your application.


Please subscribe me to:

 

You chose the industry type of "Other"

Please enter the industry that you work in:
Please enter the industry that you work in:
 
X
Info
X
Info
{taasPodcastNotification}
Live Event