63● Development of a liquid organosilane precursor,
TG − 4E, for high gas barrier film
Advanced Materials Research Laboratory

Hirokazu CHIBA
Kenji TOKUHISA

We have developed a novel precursor, TG-4E, forlayer as shown in Fig. 1. TG-4E was also used to deposit

high gas barrier film deposition by plasma enhanced

multilayer as shown in Fig. 2, and the three layers

chemical vapor deposition (PECVD). Colorless,were deposited by PECVD using the same precursor

transparent, and flexible gas barrier films were obtained,

under different deposition conditions. The first andand furthermore, the water vapor transmission rate

third gas barrier layers were deposited under the same(WVTR) of the three-layer coated film achieved 4.1 ×condition as the gas barrier film illustrated in Fig. 1−5

2

10 g/m /day under 40℃, 90%RH condition.

was deposited. The second layer was deposited underrelatively lower plasma power condition compared to1． Introduction
Recently flexible organic light emitting diodethe first and third ones for adjusting the internal stressof the multilayer. The total thickness of the three layers
was 2000nm.

(OLED) devices have attracted much attention. Since
OLED devices are easily degraded by moisture andGas barrier layer

oxygen, transparent and flexible films with high gas

Hard coat layer

barrier property are strongly needed to encapsulate

PEN

the devices. Although plastic films are transparent andflexible, these films are not suitable for this application

Fig.１

because of their poor water vapor barrier property. To

A cross−sectional view of the gas barrier
layer deposited on PEN substrate

improve the barrier property, various gas barrier layers
deposited on plastic films have been studied [1,2,3,4,5].

3rd gas barrier layer

Inorganic gas barrier layers such as silicon dioxide

2nd gas barrier layer

and aluminum oxide deposited by sputtering,

1st gas barrier layer

chemical vapor deposition (CVD), and atomic layer

Hard coat layer

deposition (ALD) have been widely investigated for thisPEN

application. However, these layers have some problems
such as their barrier property, color, deposition rate,

Fig.２

A cross−sectional view of the gas barrier
layers stacked on PEN substrate

crack, use of explosive gas, and process complexity.
In this paper, we report high gas barrier layers［2］Evaluation of thin film properties

deposited by PECVD using a novel precursor, TG-Film thickness was calculated approximately by cross-

4E. These gas barrier layers have enough gas barrier

sectional scanning electron microscopy (SEM) image.

property and are colorless, transparent, and flexible.

The WVTR was evaluated by a gas chromatographymethod and Ca test. Film composition and average

2. Experiment［1］Gas barrier film deposition

surface roughness, Ra, were measured by X-ray
photoelectron spectroscopy (XPS) and by atomic force
microscopy (AFM) using Nano Scope IIIa (Bruker AXS

TG-4E was examined to deposit an 800 nm thickCo., ltd.) respectively. Visible light transmittance andgas barrier layer by PECVD using oxygen gas on ahaze value were analyzed by spectrophotometer U-4100

polyethylene naphthalate (PEN) film with a hard coat

(Hitachi High-Technologies Corporation) and hazeTOSOH Research & Technology Review Vol.59（2015）

64

meter, respectively.

3. Results and discussions
Film deposition experiment under various conditions
was examined, and the results of deposition rate andWVTR of the films varied up to 450nm/min and range
from 10 − 1 g/m2/day to 10 − 5 g/m2/day, respectively.
More details of high gas barrier films whose deposition

Fig.３

AFM images of the gas barrier film surface deposited on
PEN substrate (a) and the surface of PEN substrate (b)rate and WVTR were range from 70nm/min to 100nm/
min and from 10 − 4 g/m 2 /day to 10 − 5 g/m 2 /day,on PEN substrate and PEN substrate were 88.2% andrespectively, were discussed.

88.3%, respectively.

Film properties of an 800 nm thick gas barrier layer

The haze value was also measured and compareddeposited from TG-4E on PEN substrate were evaluatedto that of PEN substrate. The results of gas barrier

and the results are summarized in Table 1.

layer on PEN and PEN substrate were 0.86% and 1.03%,

Gas barrier film composition measured by XPS wasrespectively. These results imply that the gas barrier

SiO2. Carbon and nitrogen contents were under theirlayer deposition did not change the optical transparency.
Bending test with 10 mm φ glass stick was examined

detection limit.
The surface roughness of the gas barrier film andfor the gas barrier film from TG-4E. After bending

PEN film were measured by AFM, and the surface

20 times, WVTR value did not change. This result

images were illustrated in Fig. 3(a) and (b). Ra value

indicated that the gas barrier film has enough flexibilityof the gas barrier film surface was 0.68 nm, and thatfor flexible devices.

of PEN substrate was 0.71nm. It shows that the film

To improve the gas barrier property, three layers
were deposited instead of the single 800 nm gas barrier

deposited from TG-4E is flat enough.
Optical transparency was evaluated by the average

layer using the same precursor under different plasma

value of transmittance range from 380 nm to 780 nm.

conditions as shown in Fig. 2. Total thickness of theThe average value is in Table 1, and experimental data

three layers was 2000 nm and its appearance wasof PEN substrate and PEN substrate with gas barrier

colorless and transparent. As a result of Ca test, WVTRlayer from TG-4E was shown in Fig. 4. The averageof the film with three gas barrier layers achieved 4.1 ×visible light transmittance value of the gas barrier layer

10 − 5 g/m2/day under 40℃, 90%RH condition.

Table１

Gas barrier film properties
Gas barrier layer
on PEN film

PEN film

Precursor−

TG−4E−Thickness（gas barrier layer）

nm

800

−WVTR（GC method）

g ／ m2 ／ day＜2.0×10−4100−101

Film composition（XPS）−

SiO2−Ranm

0.68

0.71

Average light transmittance（380−780nm）％88.288.3Haze％

0.86

1.03−

colorless andtransparent

colorless andtransparent

times

＞20−

Appearance
Bending durability（10mmφ）

東ソー研究・技術報告第 59 巻（2015）

65100
Light transmittance［％］

9080
7060
5040
Gas barrier layer deposited on PEN substrate

3020

PEN substrate

100350

450

550

650

Wavelength［nm］

Fig.４

Visible light transmittance of gas barrier layer
deposited on PEN substrate and PEN substrate

4. Conclusions
We have developed a novel precursor, TG-4E, forhigh gas barrier film deposition by PECVD, and the gas
barrier films deposited from TG-4E showed excellent
gas barrier properties. Colorless, transparent, andflexible films with a single gas barrier layer depositedfrom TG-4E were obtained. Furthermore, WVTR ofthe three-layer coated film achieved 4.1 × 10 − 5 g/m2/
day under 40℃, 90%RH condition. We believe that thethree-layer gas barrier film has enough property to beapplied to OLED devices.

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