Radiation imagery chemistry: process – composition – or product th – Registration or layout process other than color proofing
Reexamination Certificate
1999-07-07
2001-06-26
Huff, Mark F. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Registration or layout process other than color proofing
C430S030000
Reexamination Certificate
active
06251550
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to semiconductor manufacturing equipment, and more particularly, to a photolithography system for use in the manufacture of semiconductor integrated circuit devices.
In conventional photolithography systems, the photolithography equipment requires a patterned mask to print a mask pattern on a photo resist coated surface or subject. The subject may include, for example, a semiconductor substrate. The conventional patterned mask or photomask may include, for example, a quartz glass mask. In addition, with the conventional photolighographic system, a photo resist coated subject must be aligned to the mask very accurately using some form of mechanical control and sophisticated alignment mechanism. The cost of the conventional patterned mask is very expensive also, in addition to a typically very long mask purchase lead time. The long mask purchase lead time is not very helpful when a short product development cycle is desired. Still further, if a particular mask design is found to require a design change in the pattern, no matter how small of a change, then mask modification cost and a respective lead time to implement the required change can cause serious problems in the manufacturing of the desired product.
In typical integrated circuit design activity, a particular mask may be modified or undergo modification on the order of seven to eight times, maybe even more, before completion of the design activities associated with a particular integrated circuit. Naturally, total cost of making the mask is very expensive and can become cost prohibitive. In addition, a corresponding total lead time becomes very long as a result.
Still further, in conventional photolithography systems for integrated circuit fabrication and other applications, such as printed circuit board manufacturing, the use of a printed mask is required for disposing a desired mask pattern onto a resist coated subject. The printed mask is typically made at a mask printing manufacturer or mask shop, for example, with the use of a very sophisticated electron beam direct writing system or photography system to print a desired design pattern onto a transparent substrate material, such as a quartz glass plate. In addition, highly sophisticated computer systems may also be necessary.
With respect to the manufacture of semiconductor integrated circuit devices, for example, one disadvantage with the use of a conventional patterned mask is that conventional patterned masks increase the manufacturing cost of the semiconductor integrated circuit devices. The use of conventional patterned masks furthermore undesirably lengthens a manufacturing cycle time in terms of a given mask purchase cycle time. Mask purchase cycle time includes the time involved in the purchasing of a desired mask from a mask vendor for use in the patterning of a photo resist coated surface. Still further, with a conventional patterned mask, when light is directed through the pattern thereof, for example where the pattern includes sub-micron slits and feature sizes, the light is subject to being diffracted in an undesirable manner. As a result, a complicated lens system is required to compensate for the effects of the undesired diffracted light.
Referring briefly now to
FIG. 1
, a conventional photolithography system
10
is illustrated. The photolithography system
10
includes a light source
12
, a first lenses system
14
, a printed mask
16
, a mask alignment system
18
, a second lenses system
20
, a subject
22
, and a subject alignment system
24
. Subject
22
includes a photo resist coating
26
disposed thereon. During photolithography, light
28
emanates from the light source
12
, through the first lenses system
14
, the printed mask
16
, the second lenses system
20
, and onto the subject
22
. In this manner, the pattern of the mask
16
is projected onto the resist coating
26
of the subject
22
.
It would thus be desired to provide a photolithography system and method which overcomes the above mentioned problems in the art.
SUMMARY OF THE INVENTION
The present embodiment includes a novel photolithography system and method for photolithography which requires no use of conventional pattern masks for the printing of a pattern on a photo resist coated surface.
One feature of the present embodiments is that an electrical alignment is used, wherein the electrical alignment provides an improved alignment accuracy over that of a conventional mechanical alignment.
Another feature of the present embodiments includes an improved photolithography system wherein light diffraction problems associated with conventional photolithographic masks are eliminated.
Still further, another feature of the present embodiments is that the problems in the art as discussed herein above are overcome with the use of a computer generated mask pattern displayed with the use of an LCD display or through the use of micro mirror arrays.
According to one embodiment of the present disclosure, a maskless photolithography system includes a unique computer controlled pattern generator. Two types of pattern generation are used. In a first type of pattern generation, the pattern is produced with the use of a liquid crystal display or LCD panel. The first type of pattern generation is referred to herein as the LCD display method. In a second type of pattern generation, the pattern is produced with the use of micro mirror arrays or a digital mirror device (DMD). For the purpose of this invention, a digital mirror device is also referred to as a deformable mirror device. The second type of pattern generation is referred to herein as the DMD display method.
With the use of either of the two pattern generation methods as discussed herein for creating a pattern under computer control, the lithography system achieves a significant performance improvement over conventional lithography systems. In addition, with the present embodiments, conventional photolithography masks are not required. Still further, the requirement for an elaborate alignment system for use with the subject is eliminated, and thus no longer required. Lastly, the photolithography system cost is very much reduced, resulting from the elimination of the requirement for a precision mask stage and alignment system.
Furthermore, with respect to semiconductor manufacturing, conventional semiconductor integrated circuit mask making costs and the mask purchase cycle time for the photolithographic process are eliminated. In accordance with the present embodiments, no printed mask is required to be produced which advantageously eliminates any mask purchase cycle time. As a result, a semiconductor integrated circuit manufacturing process is further improved over known techniques with respect to the photolithography process steps. The manufacturing cycle time is improved (i.e., reduced).
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Singh-Gasson, Sangeet, et al.,Maskless Fabrication of Light-Directed Oligonucleotide Microarrays Using a Digital Micromirror Array, vol. 17, No. 10, Oct. 1999, pp. 974-978.
Devitt, Terry,Advance May Put Gene Chip Technology on Scientists' Desktops, http://www.biotech.wise.edu/Education/biotechnews/GeneC
Ball Semiconductor Inc.
Haynes and Boone LLP
Huff Mark F.
Mohamedulla Saleha R.
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