November 12, 2008
Kurita Develops Ultrapure Water Production System Using Nanosaver™
- Reduces Hydrogen Peroxide to Trace Amount -
Kurita Water Industries Ltd. ("Kurita," headquartered in Shinjuku, Tokyo, CEO: Hiroshi Fujino) has developed an ultra pure water production system using its hydrogen peroxide removal technology, Nanosaver™, in response to the need for ultra high purity water for use in semiconductor manufacturing processes.
Nanosaver™ reduces the concentration of hydrogen peroxide to less than 1 ppb by the use of special filler, thereby meeting the standard required for next-generation ultra pure water. As the miniaturization of processed semiconductors proceeds, the oxidation of wafers due to the presence of hydrogen peroxide, which was not deemed an issue in the past, is now considered to be potentially problematic. The application of Nanosaver™ to ultrapure water production systems will help avoid such problems.
Kurita plans to target its new ultrapure water production system incorporating the Nanosaver™ technology at next-generation semiconductor plants to be constructed in the future.
1. Background to the development
- (1)Measures to improve the purity of ultrapure water used in semiconductor manufacturing processes
In recent years, due to the rapid miniaturization of semiconductors and simultaneous increase in capacity, it has become necessary to further boost the purity of the ultrapure water used in the cutting-edge semiconductor and wafer manufacturing processes.
- (i)Ultrapure water
Ultrapure water is the water used for cleaning in the semiconductor and liquid crystal manufacturing fields. Ultrapure water is produced by removing all impurities from regular water, including microorganisms, fine particles, ions, organic matter, and dissolved oxygen as far as possible, resulting in a solution of pure H2O, or 100% water.
Small semiconductor integrated circuits used in cell phones and computers are subjected to a range of processes during their manufacture. Each process involves the use of a variety of chemical substances, which often become attached to the circuits and must be removed before the next process. Ultrapure water is used for the washing process.
The purity of ultrapure water has been improved as the miniaturization and capacity of semiconductors increases. Today’s semiconductor integrated circuits are as small as 100 nanometers (nm) or less in width, and the water used to clean these very small circuits is of the highest purity possible.
- (ii)Ultrapure water quality required for current and next-generation semiconductor manufacturing processes (estimated by Kurita)
|Impurity, etc.||65 nm or more (current ultrapure water)||45 nm or less (Next-generation ultrapure water)|
|Resistivity||> 18.2 MΩ, cm||> 18.2 MΩ, cm|
|Number of fine particles (0.03 μm)||< 5/mL||< 5/mL|
|Number of microorganisms||< 0.1/L||< 0.1/L|
|Organic matter (TOC)||< 1 ppb||< 1 ppb|
|Dissolved oxygen||< 1 ppb||< 1 ppb|
|Silica||< 0.1 ppb||< 0.1 ppb|
|Heavy metal ions||< 1 ppt||< 1 ppt|
|Hydrogen peroxide||– (Uncontrolled*)||< 1 ppb|
- *Usually 5–20 ppb
Note: ppb = parts per billion; ppt = parts per trillion
- (2)Hydrogen peroxide in ultrapure water
At present, the purity of ultrapure water used in semiconductor manufacturing is strictly controlled for several items, including resistivity, number of fine particles, concentration of organic matter and others. The concentration of dissolved matter is also controlled to less than 1 ppb (less than 1 ppt for heavy metal ions) but unlike these strictly controlled factors related to water quality, the concentration of hydrogen peroxide is rather high (5 to 20 ppb) in ultrapure water.
Semiconductor manufacturers have been concerned that hydrogen peroxide, the concentration of which was not traditionally controlled, may cause wafer oxidation during the manufacturing process of next-generation semiconductors, which could in turn result in defective products.
Kurita has responded to these concerns by developing the Nanosaver™, which can reduce the concentration of hydrogen peroxide to less than 1 ppb, improving the quality of ultrapure water to the standard that is required for the manufacture of next-generation semiconductors.
2. Nanosaver™ reduces hydrogen peroxide to a trace amount
- (1)Product outline
Nanosaver™ has special filler that reduces the concentration of hydrogen peroxide in ultrapure water to less than 1 ppb, thereby supplying ultrapure water that meets the standard required for next-generation processes.
- (2)Application to ultrapure water production systems
Incorporating Nanosaver™ into an ultrapure water production system assures a stable supply of ultrahigh purity water. Kurita received its first order for a Nanosaver™ ultrapure water production system from a customer in the electronics industry and delivered the system to the customer in July 2008.
- (3)Future development
As technological innovations in the semiconductor field progress rapidly, hydrogen peroxide-free ultrapure water will become the standard cleaning water for next-generation semiconductor manufacturing processes, with demand for such water expected to increase accordingly. Kurita therefore expects that its proactive efforts to promote sales of its Nanosaver™ ultrapure water production system to customers in the semiconducting manufacturing field will be met with success.