Radiation imagery chemistry: process – composition – or product th – Including control feature responsive to a test or measurement
Reexamination Certificate
1997-10-02
2001-07-24
Angebranndt, Martin J. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Including control feature responsive to a test or measurement
C430S022000, C430S005000, C430S394000, C356S401000
Reexamination Certificate
active
06265119
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for producing semiconductor devices by a photolithography step.
DESCRIPTION OF THE RELATED ART
In order to produce semiconductor devices, photolithography techniques have been hitherto used, in which a mask (reticle) with a circuit pattern formed thereon is illuminated with light to perform transfer (exposure) onto a semiconductor substrate (wafer) with a photosensitive material applied thereon. In such a photolithography step, positional adjustment for exposure has been performed by introducing process control marks indispensable for production such as alignment marks, registration marks, focus marks, and line width control marks into, for example, spaces between chips formed on a wafer, namely onto scribe lines.
As the integration of semiconductors increases, and the line width of patterns used is finely miniaturized, it is required to use more accurate positional adjustment techniques (alignment techniques) for reticles and wafers, automatically focusing techniques (autofocus techniques), and high performance optical techniques. In response to the requirement, the variety and the number of process control marks to be used have increased.
However, in the conventional art as described above, these marks were imprinted on the spaces between chips or on the scribe lines, and hence the superficial content and the width for imprinting the marks were restricted. Accordingly, it becomes difficult to imprint a desired number of marks with desired sizes.
On the other hand, it is desirable to make the line width of the scribe lines as narrow as possible, because a cutting speed of a dicing saw for cutting a wafer along the scribe lines can become faster and the number of acquirable chips can increase with narrower line width of the scribe lines. Accordingly, it seems that the demand to narrow the line width of the scribe lines will become stronger in future.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method for producing semiconductor devices in which all control marks to be used can be easily imprinted on a wafer, and thus the line width of scribe lines can be made narrow.
According to the present invention, there is provided a method for producing semiconductor devices including a photolithography step, comprising:
forming process control marks in the photolithography step on areas on a semiconductor substrate which are intended to be finally used as continuity areas for deriving external wiring or on areas in the vicinity thereof, the process control marks being used in the photolithography step; and
forming the continuity areas after forming the process control marks.
According to the present invention, the process control marks are formed on the areas on the wafer intended to be finally used as the continuity areas for deriving the external wiring, for example, on bonding pad areas, or on the areas in the vicinity thereof. Thus the process control marks are formed on the areas having a much broader superficial content as compared with the scribe line areas. Therefore, even if the number of process control marks to be used is increased, or if the marks themselves are large, all of them can be easily imprinted on the wafer. In addition, no mark remains at all on a formed chip pattern because insulating layers and bonding pads are formed in the following steps on the process control marks which were formed on the bonding pad areas. The process control marks may be formed between the areas on which the bonding pads are intended to be formed.
According to another aspect of the present invention, there is provided a method for producing semiconductor devices by using photolithography, comprising the steps of:
illuminating a mask containing a circuit pattern for forming semiconductor devices to transfer the circuit pattern onto a semiconductor substrate;
illuminating a mask containing a process control mark pattern to transfer the process control mark pattern onto areas on the semiconductor substrate which are intended to be finally used as continuity areas for deriving external wiring or onto areas in the vicinity thereof;
performing positional adjustment necessary to transfer the circuit pattern or another circuit pattern onto the semiconductor substrate by using the process control marks transferred onto the semiconductor substrate; and
forming the continuity areas after performing the positional adjustment.
In the present invention, the process control marks include, for example, alignment marks, registration marks, focus marks, and line width control marks. When two types of marks are used, namely marks which should be accommodated in the scribe line areas due to their properties, and marks which are not so, enough area for the former can be easily obtained on the scribe line by forming the latter on the bonding pad area. The photolithography is performed in accordance with an exposure system, such as, the step-and-repeat system, the slit scan system, the mirror projection system, the proximity system, and the contact system.
According to still another aspect of the present invention, there is provided a method for producing semiconductor devices, comprising the steps of:
illuminating a mask containing a circuit pattern for semiconductor devices to successively perform projection and exposure with the pattern through a projection optical system on a photosensitive semiconductor substrate in accordance with an exposure system in which stepping of the substrate and exposure are repeated by turns;
developing the circuit pattern subjected to the exposure; and
forming continuity areas for deriving external wiring;
wherein, prior to forming the continuity areas, a mask containing a process control mark pattern is illuminated to transfer the process control mark pattern onto areas on the semiconductor substrate which are intended to be finally used as the continuity areas for deriving the external wiring or onto areas in the vicinity thereof and positional adjustment necessary for an exposure operation in the system is performed by using the process control marks transferred onto the semiconductor substrate.
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Thompson et al., “Introduction to Microlithography” ACS symposium pp. 4-7, 1983.*
Elliott, David J., “Integrated Circuit Fabrication Technology” McGraw-Hill, pp. 1-3 and 43-61, 1982.*
Thompson et al. “introduction to Microlithography”, pp. 16-23, 1983.*
Thompson et al. “Introduction to Microlithography” (© 1983) pp. 16-23.
Angebranndt Martin J.
Nikon Corporation
Oliff & Berridg,e PLC
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