The semiconductor industry is enjoying the “Semiconductor super cycle” catalyzed by the pandemic. In addition, the variety of semiconductor chips are increasing driven by electronification of everything resulting the demand for laser based mask writers are increasing due to lower exposure cost per mask. However, many laser mask writers in operation today are getting old.
As a response to the growing demand Mycronic introduced SLX series, a new generation cost-efficient laser mask writer and the superiority of the system is demonstrated by sharing recent evaluation data with two different laser sources.
A New Generation Cost-efficient Laser Mask Writer for
Mature Semiconductor Nodes
Mycronic introduces SLX series – a new generation cost-efficient laser mask writer – to meet the ever increasing demand for laser based photomask writer driven by new semiconductor trends such as “More than Moore” and “Electronification of everything”. Photomasks of mature design nodes are required due to large variety of designs combined with price-sensitive low volume manufacturing.
In this paper, Mycronic shares key technologies used in SLX series and how to achieve the cost effective mask manufacturing and demonstrates the superiority of the system by trecent evaluation data.
Large-field projection lithography for FPDs has developed gradually since the 90s. The LCD screen technology has remained largely unchanged and incremental development has given us better image quality, larger screen sizes, and above all lower cost per area. Recently new types of mobile devices with very high pixel density and/or OLED displays have given rise to dramatically higher requirem ents on photomask technology. Devices with 600 ppi or m ore need lithography with higher optical resolution and better linewidth control. OLED di splays pose new challenges with high sensitivity to transistor parameters and to capacitive cross-talk. New mask requirements leads to new maskwriter requirements and Mycronic has developed a new generation of large -area mask writers with significantly improved properties. This paper discusses and shows data for the improved writers. Mask production to high er quality stan dards also need metrology to verify the quality and Mycronic has introduced a 2D metrology tool with accuracy adequate for current and future masks. New printing or additive methods of producing disp lays on plastic or metal foil will make low-cost disp lays available. This inexpensive type of disp lays will exist side by side with the photographic quality displays of TVs and mobile devices, which will continue to be a challenge in terms of mask and production quality.
Ge islands fabricated on Si(100) by molecular beam epitaxy at different growth temperatures, were studied using crosssectional
scanning transmission electron microscopy and energy-dispersive X-ray spectrometry combined with electron energy loss spectrometry experiments. The island size, shape, strain, and material composition define the dot-related optical transition energies, but they are all strongly dependent on the growth temperature. We have performed quantitative investigations of the material composition of Ge/Si(001) quantum dots. The samples were grown at temperatures ranging from 430 to 730 oC, with one buried and one uncapped layer of Ge islands separated by 140 nm intrinsic Si. The measurements showed a Ge concentration very close to 100 % in the islands of samples grown at 430 oC. With a growth temperature of 530 oC, a ~20 % reduction of the Ge fraction was observed, which is due to intermixing of Si and Ge. This is consistent with our previous photoluminescence results, which revealed a significant blue shift of the Ge dot-related emission peak in this growth temperature range. The Ge concentration decreases more slowly when the growth temperature is increased above 600 oC, which can be explained by geometrical arguments. The longer distance between the interface and the core of these larger sized dome-shaped islands implies that less Si atoms reach the dot center. In general, the uncapped Ge dots have similar widths as the embedded islands, but the height is almost exclusively larger. Furthermore, the Ge concentration is slightly lower for the overgrown dots.
For Si1-xGex/Si hole and Ga1-xAlxAs/GaAs electron double barrier resonant tunneling devices (RTDs), we have studied the negative differential resistance (NDR). The current peak-to-valley ratio (PVR) was investigated as function of the temperature T for different device parameters and the dependence of the maximum working temperature Tm on material parameters and device parameters was determined. The results show that by narrowing well and barrier width, decreasing barrier height, and decreasing the doping concentration in the spacer layer, the RTDs have improved temperature characteristics, and have higher peak current Jp and larger PVR at high temperature. The RTDs with larger well width, and wide and high barriers nave quite large PVR, and are favorable to use at low temperature. Ga1-xAlxAs/GaAs electron RTDs are estimated to work at room temperature for a wide range of device parameters, while the device parameter design of Si1-xGex/Si hole RTDs is much more critical to work at same temperature. These results are consistent with the tendency of recently published experiments. On the basis of calculated PVR curves we can optimize RTD parameters to increase the working temperature and current peak-to-valley ratio.
Studies of current-voltage (I-V) characteristics and their temperature dependence show that the current transport in MBE-grown Si1-xGex/Si diodes is closely related to the epitaxial film quality. It is mainly controlled by two different mechanisms at low and high temperature. The ideality factor n of the diodes increases as the temperature is reduced, and n increases faster for the diodes which have larger n at room temperature. From comparisons with calculated results, it is proposed that the transport mechanism is diffusion controlled at high temperature and defect-assisted tunneling controlled at low temperature. The
results from ? irradiation studies also support this suggestion. Due to the existence of band-offsets, the shift of the I-V curve with temperature of p+-Si1-xGex/n-Si diodes is much smaller than that in n+-Si1-xGex/p-Si diodes, when the current is diffusion controlled. The band-offsets are estimated from these shifts, and the results are in agreement with values measured by another method.
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