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SEMICON Japan 2022 (December 14-16)


SSEMICON Japan 2022 New oxide target material has been mass-produced for LCD and OLED

December 14-16, SEMICON Japan 2022 was held in Tokyo Big Site. Main topics of display in this exhibition are picked up.


New oxide target material as a replacement for IGZO target appeared rapidly

As concerns material, Kobelco Research Institute exhibited an original oxide target material "KOS-BO3C" for oxide-TFT. It's composed of 3 - 4 elements, competitive with IGZO (InGaZnO) target. Its carrier mobility of pilot produced device (the back channel type) is 29.1 cm2/Vs, which is 3 times and over than that of IGZO-TFT. And also, Vth and SS factor are relatively superior such as 0.5 V and 0.17 V/dec respectively. Furthermore, Vth shift at visible light irradiation can be suppressed lower than that of IGZO-TFT.


Pic.1 Oxide target with 450 ㎜ diameter
Of course, its film can be deposited by the DC sputtering method, and patterned by the wet-etching method using acid. And also, it's possible to correspond single substrate processing and inline processing at sputtering deposition. For this reasons, TFT maker can use this target in the existing mass production line of a-Si TFT and IGZO-TFT at produced line changing-free. Furthermore, typical deposition temperature is 300 ℃ and under, however, it can be deposited at low temperature same as 100 ℃. In short, it can be correspond to flexible-TFT using plastic substrate.

It has been used in mass-production line of TFT-LCD and AM-OLED recently because of the above features. By the way, picture 1 (circle type) is useful for semiconductor category. For display use, divided target (tilting of 450 ㎜ width) is de-fact standard at the present moment.

Dependence of IPCE on incident light strength is minimized because of original p-type polymer

As regards material for solar cell, Toyobo disclosed a polymer type organic film solar cell. It's a bulk-hetero junction device using solution processed light absorption layer, is composed of n-type polymer (PCBM) and an original p-type polymer. Its incident photon-to-current efficiency (IPCE) of pilot-produced device was 10 %.


Pic.2 Pilot-produced organic film solar cell


Fig.1 Comparison of IPCE
※blue:Whole irradiation, orange:irradiation at 50 % area

Most feature is minimum dependence of IPCE on incident light strength. Figure 1 shows comparison of IPCE. In this time, blue is IPCE at whole irradiation (100 %), orange is IPCE at irradiation at 50 % area. IPCE of this polymer device was not almost reduced at irradiation at 50 % area, on the other hand, that of a-Si solar cell was greatly reduced, and not almost generated at this state. But, this feature is common with all organic film solar cells. As concerns this question, the company explained this independence was lower because of function of p-type polymer. In fact, relatively high IPCE in low illumination environment same as 200 lx is also most same as IPCE in high illumination environment.

By the way, the company will release this p-type polymer, and can supply pilot-produced device for estimation of material.

Koshibu exhibited a master mold for micro lens film with fine 3D shape structure


Pic.3 Master mold for micro lens array film
With respect to optical film, Koshibu exhibited a master mold for micro lens array film.
It's a glass mold with 3D shape pattern of thick photoresist. If it's used for optical film such as micro lens array film, Ni film is electroformed on this mold by the electroplating method, and then, it is patterned by the nanoimprinting method.

The company fabricates thick photoresist pattern. In the booth, large sample same as 400 × 400 ㎜ was exhibited. The company demonstrated to supply large substrate.

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