Electricity: measuring and testing – Impedance – admittance or other quantities representative of... – Lumped type parameters
Reexamination Certificate
1997-11-25
2001-04-17
Brown, Glenn W. (Department: 2858)
Electricity: measuring and testing
Impedance, admittance or other quantities representative of...
Lumped type parameters
C324S699000, C324S629000
Reexamination Certificate
active
06218847
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a test pattern for measuring the thickness of an insulating layer and a method for measuring a thickness of the insulating layer using the test pattern.
2. Description of the Related Art
It is often required to measure the thickness of an insulating layer form ed on wiring patterns of a semiconductor device.
It is known, in general, that the thickness of an insulating layer formed on wiring patterns varies between a region where wiring patterns are formed with high density and a region where only one wiring pattern is formed in an isolated manner after the planarization (Reference:
Logic LSI Innovation
, Science Forum Co. ltd., 1995, pp. 265-269). More specifically, it is known that the thickness of the insulating layer formed on wiring patterns arranged with high density is thicker than the insulating layer formed on an isolated wiring pattern, that is, a wiring pattern with low density. This is due to the difference in coating conditions of a coating layer (SOG layer) coated during flattening process.
Therefore, it is necessary to measure the thickness of an insulating layer which has been formed on wiring patterns and flattened by using planarization(flattering) technique, for example, when designing semiconductor device manufacturing process so as to know the uneven step coverage of a base.
As a method for measuring the thickness of an insulating layer formed on wiring patterns, there has been proposed a method using an optical measuring apparatus or using a capacitance measuring apparatus.
In the layer thickness measuring method by the optical measuring apparatus, light is applied to a target or an insulating layer to measure the layer thickness from the reflectance factor. In the method by the capacitance measuring apparatus, the capacitance of an insulating layer formed between an upper wiring pattern and a lower wiring pattern is measured after the flattening processing has been completed, to calculate the layer thickness based on the measurement value.
However, when the thickness of an insulating layer formed on wiring patterns is measured by using the above methods, there are the following problems.
In the method using these conventional measuring apparatus (such as an optical film thickness measuring apparatus and a capacitance measuring apparatus), if the surface area of a wiring member (conductive layer) forming wiring patterns is relatively large, the thickness of an insulating film on the wiring patterns can be measured at relatively high precision. On the other hand, if the thickness of an insulating film on fine wiring patterns where the surface area of a wiring member (a conductive layer) forming wiring patterns are small or the width of the wiring member (conductive layer) is narrow, then a measurement error becomes large and the film thickness cannot be measured at high precision.
Therefore, it is difficult to precisely measure the thickness of an insulating layer on wiring patterns in a region a fine wiring pattern arranged in an isolated manner, that is, arranged with low density. Accordingly, it is impossible to measure the thickness difference between a region where fine wiring patterns are arranged with high density and a region where a fine wiring pattern is arranged in an isolated manner.
It has been desired to measure the thickness of an insulating layer formed on wiring patterns even in a region where a fine wiring pattern is isolated, that is, arranged with low density.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a test pattern used for measuring the thickness of an insulating layer formed on wiring patterns.
It is another object of the present invention to provide test pattern used in measurement in which the thickness of an insulating layer formed on wiring patterns can be easily and precisely measured.
It is yet another object of the present invention to provide a test pattern for use in a measurement for easily and precisely measuring the thickness of an insulating layer formed on wiring patterns even in a region where a fine wiring pattern is isolated, that is, arranged with low density.
It is yet another object of the present invention to provide a test pattern for use in a measurement for precisely measuring the difference in the thickness of an insulating layer derived from the different density degree of wiring patterns.
Moreover, it is an object of the present invention to provide a method for measuring the thickness of an insulating layer formed on wiring patterns.
In addition, it is an object of the present invention to provide a method used for easily and precisely measuring the thickness of an insulating layer formed on wiring patterns.
Furthermore, it is an object of the present invention to provide a method used for precisely measuring the thickness of an insulating layer varying according to the density degree of the wiring patterns.
The present invention provides a test pattern for use in measuring the thickness of the insulating layer comprising: a wiring pattern provided in an insulating layer and having a resistance value depending on a thickness of the insulating layer; and a dummy pattern provided in the insulating layer adjacent to the wiring pattern and allowing the thickness of the insulating layer to be directly measured.
According to the test pattern of the present invention, it is possible to measure the resistance value of a certain wiring pattern provided in the insulating layer having a certain thickness. Therefore, by providing test patterns for a plurality of insulating layers having different thicknesses, respectively, and measuring the resistance value of each wiring pattern and the thickness of the insulating layer using the dummy pattern, it is possible to prepare a characteristic chart showing how the resistance value of a certain wiring pattern corresponds to the thickness of the insulating layer where the wiring pattern provided. It is possible to measure the thickness of an insulating layer indirectly by providing a wiring pattern in the insulating layer having a unknown thickness, measuring the resistance value thereof and applying the measured value to the characteristic chart above.
According to the present invention, it is preferable that the wiring pattern includes a through hole contact extending through the insulating layer and has a resistance value depending on the thickness of the insulating layer.
It is also preferable that the wiring pattern includes a lower wiring pattern arranged under the insulating layer and an upper wiring pattern arranged on the insulating layer; and the through hole contact connects the upper wiring pattern and the lower wiring pattern.
It is further preferable that the lower wiring pattern comprises a plurality of lower wiring parts linearly arranged at intervals; and a plurality of the through hole contacts are provided; and the plurality of through hole contacts connect the lower wiring parts and the upper wiring parts.
It is also preferable that the upper wiring parts are arranged to be partially overlapped with adjacent two the lower wiring parts in a vertical direction, respectively; and the through hole contacts connect the upper wiring parts and adjacent two the lower wiring parts positioned below the upper wiring parts, respectively.
It is preferable that the dummy pattern is arranged along the linearly arranged upper wiring pattern and lower wiring pattern.
In addition, it is preferable that the dummy pattern is arranged on both sides of the wiring pattern.
It is preferable that the dummy pattern comprises a lower dummy pattern part arranged under the insulating layer.
It is preferable that the dummy pattern allows the thickness of the insulating layer thereon to be optically measured.
It is preferable that the dummy pattern includes an upper dummy pattern part arranged on the insulating layer.
It is preferable that the dummy pattern allows the thickness of the insulating layer thereon to be capacitancially measured.
In another asp
Brown Glenn W.
Jones Volentine, L.L.P
OKI Electric Industry Co., Ltd.
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