Patent Application
20140170565
This application is based upon and claims benefit of priority from the Japanese Patent Application No. 2012-272678, filed on Dec. 13, 2012, the entire contents of which are incorporated herein by reference.
Embodiments described herein relate generally to a pattern forming method and a method for manufacturing a template for imprint.
As a technique for forming a fine pattern at low cost, a photo nanoimprint method is known. This is a method where a template having concavities and convexities corresponding to a pattern that is wished to be formed on a substrate is pressed onto a photo-curable organic material layer applied to the substrate surface, and irradiated with light to cure the organic material layer, and the template is then released from the organic material layer, thereby to transfer the pattern.
The template includes a master template to serve as an original and a replica template made of a copy of the master template. The replica template is used at the time of transferring a pattern onto a wafer for semiconductor device manufacturing, and it is replaced by another replica template when deterioration such as abrasion or contamination with a dust occurs.
A pattern with the same pitch as that of the pattern to be formed on the wafer is formed on the master template by electron beam drawing. A primary beam that is incident on the template substrate can be reduced to about 1 to 3 nm. However, even by use of such a fine beam, backscatter electrons radiated from the substrate in the opposite direction to the incident direction expand in the range of several tens of nm, to expose a resist to light. This leads to the same state as a state where the beam apparently blurs, where it is not possible to obtain a sufficient resolution for resolving a fine pattern, especially a pattern with a half pitch of not larger than 20 nm.
In one embodiment, a pattern forming method includes irradiating a predetermined region of a mask member, provided on a substrate, with an ion beam to inject ions, forming a self-assembled material layer having a first polymer and a second polymer on the mask member, microphase-separating the self-assembled material layer, to form first polymer section containing the first polymer and second polymer section containing the second polymer, the second polymer section being provided on the predetermined regions, removing one of the first polymer section and the second polymer section and transferring a pattern shape of the other to the mask member, and processing the substrate with the mask member used as a mask.
Embodiments will now be explained with reference to the accompanying drawings.
A pattern forming method according to the present embodiment will be described using
First, as shown in
Next, the substrate 100 is carried to the vacuum chamber 12 of the focused ion beam device shown in FIG, 1, to be subjected to positioning such as centering or rotation, and then it is irradiated with the ion beam, to inject ions into a predetermined region of the chromium film 102. The ions are injected into the surface portion of the chromium film 102, to form an ion injection region. For example, a plurality of line-shaped ion injection regions 104 each having a width of 10 nm are formed at intervals of 10 nm as shown in
Here, as an ionic species to be injected into the chromium film 102, there is used one capable of surface-reforming (surface-modifying) the chromium film 102 that shows hydrophobic properties, to make it have hydrophilic properties. For example, injecting water cluster ions into the chromium film 102 can make the ion injection region 104 hydrophilic. Further, when irradiation is performed with ions at relatively low energy (several KeV), the ions stay only in a surface portion of the chromium film 102, and that portion can be efficiently made hydrophilic.
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In the present embodiment, by ion injection using the focused ion beam device, the hard mask (chromium film 102) is separated into the hydrophilic region and the hydrophobic region in a fine and accurate manner, and using these as the chemical guide, the block copolymer is microphase-separated, to form the self-assembled pattern. Then, the hard mask is processed using the self-assembled pattern as a mask, and the substrate 100 is processed using this hard mask. Hence, it is possible to form an extremely fine pattern on the substrate 100.
The chromium film 102, which in the above embodiment is used as a hard mask, may be substituted by a chrome oxide film. In this case, as the ions to be injected by the focused ion beam device, hydrogen ions are preferably used. Injecting the hydrogen ions leads to generation of an OH group on the surface of the chrome oxide film, and the ion injection region can thus be made hydrophilic.
Further, a neutralized film may be applied onto the hard mask and ions may be injected into this neutralized film, to form the hydrophilic region or the hydrophobic region. As the ionic species, water or hydrogen can be used in the case of forming the hydrophilic region, and fluorine or silicon can be used in the case of forming the hydrophobic region.
In the above embodiment, a length of a molecule of at least one of a first polymer block and a second polymer block that are contained in the block copolymer is preferably designed to be equivalent to a width of the ion injection region 104 or the ion non-injection region.
With the pattern forming method according to the above embodiment, it is possible to facilitate formation of a fine pattern which has a half pitch of not larger than 20 nm and whose sufficient resolution cannot be obtained by electron beam drawing.
Although a plurality of line-shaped ion injection regions 104 have been formed in the above embodiment, the shape of the ion injection region 104 is not restricted to the line shape, but can be one corresponding to the shape of the pattern to be processed on the substrate 100.
Although the self-assembled material layer 106 is formed using PS-PMMA (polystyrene-polymethyl methacrylate) in the above embodiment, another material may be used such as PS-PDMS (polystyrene-dimethylpolysiloxane), PS-PEO (polystyrene-polyethylene oxide) or PS-PHOST (polystyrene-polyhydroxystyrene).
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2012-272678 | Dec 2012 | JP | national |
