Featured Research

from universities, journals, and other organizations

Slicing Silicon Blocks Into Paper-Thin Wafers For Solar Cells

Date:
August 7, 2009
Source:
Fraunhofer-Gesellschaft
Summary:
You need the right tool to slice silicon blocks into paper-thin wafers: a several-kilometer-long wire wetted with a type of grinding paste. And all the parameters must be optimally adjusted -- only then can significant material losses be avoided during the cutting process.

Using a light microscope to study sawed silicon wafer surfaces. In the foreground: a silicon block with sawed wafers, coils of wire and a finished solar cell.
Credit: Copyright Fraunhofer IWM

The ability to cut onions into thin slices isn't just a matter of practice – choosing the right implement also helps make good onion rings. The same principle applies when cutting silicon blocks to make wafers for solar cells. You need a special slicing tool to produce paper-thin wafers from silicon blocks ("ingots"): reminiscent of an egg slicer, a filigree wire is used to cut through the ingot at a speed of up to 60 km/h.

This wire is several hundred kilometers long and arranged in such a way that the ingot is sliced into hundreds of wafers simultaneously. The process takes around six hours and the resultant slices are approximately 180 m thick.

Dr. Rainer Kbler, business unit manager at the Fraunhofer Institute for Mechanics of Materials IWM, explains: "When slicing the wafers, the challenge is to reduce the saw gap width." The space between two wafers is governed by the thickness of the wire. The steel wire is wetted with a type of paste ("slurry"), a mixture of silicon carbide and polyethylene glycol. This is harder than silicon and cuts through the ingot. The gap arises where the silicon is reduced to powder during cutting. "Gap widths are currently around 180 m," says Kbler, "which means that given a wafer thickness of 180 m, we generate the same amount of waste for each silicon slice. That's inefficient."

The researchers "want to achieve smaller saw gap widths of around 100 m, which are also suitable for industrial applications." In a project funded by the federal ministry for the environment (BMU), they are currently studying the abrasion process and contact regimes using a single-wire saw and are principally interested in the interactions between the wire, the slurry and the silicon. They are also using computer modeling to simulate different configurations. What forces are at work when sawing with thin wires? How can one ensure the wire is well wetted? What is the best grain size for the slurry and how must the particles be distributed?

"We want to answer all these questions and ultimately arrive at optimal wire and slurry systems that are suitable for industrial applications," says Kbler. The researchers are currently striving to achieve gap widths of 90 m, which would represent a huge increase in efficiency as waste would be halved.


Story Source:

The above story is based on materials provided by Fraunhofer-Gesellschaft. Note: Materials may be edited for content and length.


Cite This Page:

Fraunhofer-Gesellschaft. "Slicing Silicon Blocks Into Paper-Thin Wafers For Solar Cells." ScienceDaily. ScienceDaily, 7 August 2009. <www.sciencedaily.com/releases/2009/08/090807103917.htm>.
Fraunhofer-Gesellschaft. (2009, August 7). Slicing Silicon Blocks Into Paper-Thin Wafers For Solar Cells. ScienceDaily. Retrieved September 21, 2014 from www.sciencedaily.com/releases/2009/08/090807103917.htm
Fraunhofer-Gesellschaft. "Slicing Silicon Blocks Into Paper-Thin Wafers For Solar Cells." ScienceDaily. www.sciencedaily.com/releases/2009/08/090807103917.htm (accessed September 21, 2014).

Share This



More Matter & Energy News

Sunday, September 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Thousands March in NYC Over Climate Change

Thousands March in NYC Over Climate Change

AP (Sep. 21, 2014) Accompanied by drumbeats, wearing costumes and carrying signs, thousands of demonstrators filled the streets of Manhattan and other cities around the world on Sunday to urge policy makers to take action on climate change. (Sept. 21) Video provided by AP
Powered by NewsLook.com
What This MIT Sensor Could Mean For The Future Of Robotics

What This MIT Sensor Could Mean For The Future Of Robotics

Newsy (Sep. 20, 2014) MIT researchers developed a light-based sensor that gives robots 100 times the sensitivity of a human finger, allowing for "unprecedented dexterity." Video provided by Newsy
Powered by NewsLook.com
MIT BioSuit A New Take On Traditional Spacesuits

MIT BioSuit A New Take On Traditional Spacesuits

Newsy (Sep. 19, 2014) The MIT BioSuit could be an alternative to big, bulky traditional spacesuits, but the concept needs some work. Video provided by Newsy
Powered by NewsLook.com
New Music With Recycled Instruments at Colombia Fest

New Music With Recycled Instruments at Colombia Fest

AFP (Sep. 19, 2014) Jars, bottles, caps and even a pizza box, recovered from the trash, were the elements used by four musical groups at the "RSFEST2014 Sonorities Recycling Festival", in Colombian city of Cali. Duration: 00:49 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins