Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
2002-09-30
2004-10-05
Rodriguez, Paul (Department: 2125)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C700S096000, C700S121000, C705S026640, C716S030000
Reexamination Certificate
active
06801823
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a system of ordering and supplying masks to be used in the process of manufacturing semiconductor devices. In particular, the present invention relates to a system of supplying photomasks to be used as plates for photolithography in the process of manufacturing semiconductor devices.
2. Description of the Background Art
A photomask constituted of a synthetic quartz substrate covered with shielding patterns formed of a thin metal film has been produced for use as a plate for a photolithography step which is one of the steps for manufacturing such a semiconductor integrated circuit device as IC (integrated circuit) chip.
The photomask is produced by a certain mask manufacturer. Information about the specification of the photomask is sent by being recorded on a magnetic tape for example or transmitted online from an IC chip manufacturer (order-sender) to the mask manufacturer (order-receiver). Then, the mask manufacturer prepares production data for producing the photomask according to the supplied information about the specification. With regard to information about details of the order such as the number of ordered photomasks and the delivery date, the IC chip manufacturer (order-sender) notifies the mask manufacturer (order-receiver) by telephone or online. In accordance with the information about order details, the mask manufacturer prepares control data including information necessary for quality control as well as information necessary for production control such as the product number, the number of products to be manufactured, the destination of delivery and the delivery date for example. The prepared control data is passed to a photomask production line. Following the production data prepared according to the specification and the control data prepared according to the information about order details, photomasks are produced on the photomask production line. The photomasks are produced by means of an electron beam exposure machine controlled by the production data for example.
FIG. 30
shows a reticle
8000
for an optical stepper as one example of photomasks as described above. Reticle
8000
constituted of a synthetic quartz substrate has one side on which circuit patterns
8010
and
8020
formed of a thin metal film are provided as a set of shielding patterns.
Actually, circuit patterns
8010
and
8020
each have a set of many patterns with the line-width of the order ranging from a few microns or submicrons to 0.1 micron, for example, which is not shown in FIG.
30
.
In manufacturing photomasks, the mask manufacturer should measure and evaluate the production error, i.e., the error (difference) between the design dimension and the finished dimension of an actually produced shielding pattern.
FIGS. 31A and 31B
show an element pattern
8100
included in circuit pattern
8010
on the photomask as well as how the dimension of this element pattern
8100
is measured.
In
FIG. 31A
, this element pattern is rectangular in shape. A measurement window
8200
shown in
FIG. 31B
is used for measuring the dimension of element pattern
8100
.
If the dimension of element pattern
8100
is measured by an SEM (scanning electron microscope), “measurement window” refers to a measuring region which is scanned with an electron beam and a resultant electron beam reflection image is observed to measure the dimension of element pattern
8100
.
If element pattern
8100
is measured by a laser microscope, “measurement window” refers to a measuring region to which a laser beam is directed and a resultant optical image is observed to measure the dimension of element pattern
8100
.
Thus, a larger “measurement window” provides a greater amount of measurement data which improves the accuracy of the measured dimension.
Regardless of the measurement by means of the electron beam reflection image and the optical image, the observed image in measurement window
8200
is provided as electronic data to a computer and the data of the observed image is image-processed to detect edge parts
8220
and
8210
of element pattern
8100
and measure the dimension thereof. For example, the second derivative of the intensity of the electron beam reflection image may be determined to detect the point of inflection of the reflection intensity and detect the edges from point of inflection.
In this way, the dimension is measured to evaluate any production error of photomasks.
However, if the mask manufacturer is required to evaluate the production error measured as described above and then deliver products to the IC chip manufacturer with the error guaranteed by the mask manufacturer and accordingly required to measure all dimensions of circuit patterns
8010
and
8020
, a resultant problem is that the delivery date (turnaround time: TAT) is extended and the production cost increases.
The mask pattern is produced based on design data prepared as digital data. Accordingly, the outline of each pattern is represented, for example, by a set of coordinates on a so-called “design grid” consisting of units formed by parallel bars and crossbars, one unit corresponding to the minimum design unit. Such a “design grid” is also called “address unit” for specifying positions where patterns are to be formed in producing a mask.
Each pattern on the photomask being produced is not necessarily formed of outer lines that are parallel with the bars or crossbars of the grid of “address unit” described above. For example, the pattern could have an outer line diagonal to the bars or crossbars or curved outline depending on cases.
For example, an interconnection diagonal to any bar of the design grid at an angle of 45° may be formed or a pattern of an element for which a high withstand voltage is required may be designed to have a circular outline.
In this case, the design data used for producing the mask is actually represented as a set of coordinates on a grid having values rounded by “address unit.”
In such a case, the production error between the designed pattern and any shielding pattern on the photomask is affected by round-off error. Therefore, it could be difficult to accurately evaluate manufacturing tolerance as an error between the dimension of the designed pattern and the finished dimension of the shielding pattern.
Moreover, even if outer lines of each pattern on the photomask are all in parallel with the bars or crossbars of the grid of “address unit,” the pattern on the photomask could be complex in shape.
For example, with the decreasing feature size of circuit patterns, it becomes difficult to faithfully form the pattern shape of the mask on a wafer. Then, graphics could be added to the mask pattern or optical proximity correction (OPC) could be applied for correcting the size depending on density of features. In this case, each pattern on the photomask could be complex in shape as described above. A problem here is that accurate evaluation of the pattern dimension is difficult since outer lines of a pattern are not straight lines of a predetermined length in parallel with each other.
SUMMARY OF THE INVENTION
One object of the present invention is to provide a mask supply system to shorten the period for manufacturing photomasks.
Another objet of the present invention is to provide a mask supply system to reduce the manufacturing cost of photomasks.
In summary, the present invention is a photomask supply system supplying a photomask to an order-sender. The photomask supply system includes a communication unit, a storage unit, a measuring unit, and a control unit.
The communication unit communicates with the order-sender. The storage unit stores data. The measuring unit measures, according to a measurement recipe, the dimension of a pattern on the photomask which has been produced. The control unit is connected to the communication unit and the storage unit for controlling the communication unit and the storage unit.
The control unit includes a unit for receiving specification data via the communication unit and storing the specifi
Renesas Technology Corp.
Rodriguez Paul
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