Epson, JSR Develop World's First High-Quality Silicon Film and TFTs Using Micro-Liquid Processes

Apr 06, 2006
SEM photo of sample - Epson
Sample SEM (scanning electron microscope) photo.

Seiko Epson Corp. and JSR have succeeded in creating the world's first high-quality silicon film with liquid coating and inkjet patterning processes. The performance of low-temperature polysilicon thin-film transistors (LTPS-TFTs) produced with silicon film formed by the spin coat method is comparable to that achieved when using silicon film formed using the conventional CVD method. The new technology is featured in the UK scientific journal Nature (April 6, 2006 issue).

With the growing demand for large displays such as liquid crystal televisions, there is an ever-increasing need for high-performance, low-cost TFTs. The existing process for manufacturing TFTs for use in displays requires enormous vacuum devices to form the film and expensive photolithography equipment to transfer the pattern, making it both costly and potentially harmful to the environment.

Sample cross section
Sample cross section

To address these problems, in recent years a great deal of research has been conducted on creating TFTs using organic semiconductors that can be formed from liquids. In theory, using liquid materials should not only eliminate the need for vacuum devices, but also enable the use of printing technologies such as inkjet printers to create the pattern, thereby significantly reducing energy consumption and processing time. However, the performance and reliability of existing organic TFTs are not yet sufficient for widespread use in displays. The current process makes it possible to form high-performance silicon film from liquid materials, which is the potential key to solving all of these issues at once.

The new material jointly announced by Epson and JSR Corporation is a high order silane compound of hydrogen and silicon dissolved in an organic solvent. It forms a silicon film when spin coated on the substrate and baked in an inert atmosphere. When fabricating a TFT prototype using a silicon film formed by spin coating (other than the formation of the silicon coat, the production process is the same as for conventional LTPS TFTs), the electrons achieved mobility of 108 cm2/Vs. The new material shows high potential, as this is approximately the same mobility achieved using the CVD method.

Epson used its proprietary "micro liquid processes" to demonstrate the possibilities of printed TFTs, forming a silicon film pattern onto a substrate by firing the materials onto a substrate using the inkjet method. As a result, part of the pattern formation associated with traditional photolithography is unnecessary. Forming a TFT prototype using a silicon film pattern using the inkjet method (other than the formation of the silicon coat pattern, the production process is the same as for conventional LTPS TFTs) the electrons achieved mobility of 6.5 cm2/Vs, a figure that is lower than that achieved with spin coating. Although improvements need to be made to the inkjet process, Epson believes that printed TFTs show sufficient potential.

This research was commissioned by Japan's New Energy and Industrial Technology Development Organization (NEDO), an incorporated administrative agency, as a project entitled, "Development of Manufacturing Technology for Silicon Transistors Using Liquid Materials", with the aim of advancing research on fundamental technology.

Source: Seiko Epson

Explore further: The state of shale

add to favorites email to friend print save as pdf

Related Stories

Internet trend puts users center stage

Dec 11, 2014

Sensors that track steps, pulse, diet and more marked a wearable computing fashion trend this year as they evolve from measuring what we've done to telling us what to do.

Nanoshaping method points to future manufacturing technology

Dec 11, 2014

A new method that creates large-area patterns of three-dimensional nanoshapes from metal sheets represents a potential manufacturing system to inexpensively mass produce innovations such as "plasmonic metamaterials" for advanced ...

Thin-film hybrid oxide-organic microprocessor

Dec 10, 2014

Holst Centre, imec and their partner Evonik have realized a general-purpose 8-bit microprocessor, manufactured using complementary thin-film transistors (TFTs) processed at temperatures compatible with plastic ...

Nanoscale resistors for quantum devices

Dec 09, 2014

Researchers from the London Centre for Nanotechnology have made new compact, high-value resistors for nanoscale quantum circuits. The resistors could speed the development of quantum devices for computing ...

Light propagation in solar cells made visible

Dec 05, 2014

How can light which has been captured in a solar cell be examined in experiments? J├╝lich scientists have succeeded in looking directly at light propagation within a solar cell by using a trick. The photovoltaics ...

Experts see Korean parallels in Sony hack

Dec 04, 2014

Some cybersecurity experts say they've found striking similarities between the code used in the hack of Sony Pictures Entertainment and attacks blamed on North Korea which targeted South Korean companies ...

Recommended for you

Impoverished North Korea falls back on cyber weapons

1 hour ago

As one of the world's most impoverished powers, North Korea would struggle to match America's military or economic might, but appears to have settled on a relatively cheap method to torment its foe.

Five ways to make your email safer in case of a hack attack

1 hour ago

The Sony hack, the latest in a wave of company security breaches, exposed months of employee emails. Other hacks have given attackers access to sensitive information about a company and its customers, such as credit-card ...

2012 movie massacre hung over 'Interview' decision

2 hours ago

When a group claiming credit for the hacking of Sony Pictures Entertainment threated violence against theaters showing "The Interview" earlier this week, the fate of the movie's big-screen life was all but ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.