Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
2001-07-24
2003-05-20
Picard, Leo (Department: 2125)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C700S114000, C700S121000, C700S109000, C700S103000
Reexamination Certificate
active
06567716
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device production management system, and a semiconductor device production method. More particularly, the invention relates to a production management system for managing operating conditions of wafer carrier cassettes, as well as to a semiconductor device production method involving the use of that production management system.
2. Description of the Background Art
During production of semiconductor devices, wafer carrier cassettes are managed so that the quality and yield of the semiconductor products are improved. A typical method of such management is illustratively disclosed in Japanese Patent Laid-Open No. Hei 6-183524. The disclosed method involves managing the number of times each wafer carrier cassette is used so as to forestall deteriorating conditions associated with the cassette being overused, such as deformation, friction-induced destruction of the cassette in transit, or dust emanating from the cassette itself.
A major factor responsible for deterioration in the quality and yield of semiconductor devices is the spread of contaminants over a semiconductor wafer in addition to the cassette breakdown and dust emanations mentioned above. How contaminants can spread over the semiconductor wafer is outlined below with reference to
FIGS. 20 through 23
.
FIG. 20
is a perspective view of a wafer carrier cassette
10
which contains wafers
12
and which is used during semiconductor device production. Inside the cassette
10
are a plurality of slits
14
that keep the wafers
12
in place therein.
FIG. 21
is a perspective view of a case
16
accommodating a cassette
10
. The case
16
is made up of a body
18
and a base
20
detachable from each other. A handle
22
for manually carrying the case
16
is secured to the body
18
.
FIG. 22
is an enlarged view of a tip of the wafer
12
held inside the slit
14
. As illustrated, the slit
14
and wafer
12
can bear a substance
24
emanating from semiconductor device production processes. When a wafer
12
bearing the substance
24
following a certain process is inserted into a slit
14
, the direct contact between the wafer
12
and the slit
14
leaves the substance
24
stuck inside the slit
14
. The wafer
12
is then taken out of the cassette
10
and subjected to a lower end process. Thereafter, the wafer
12
is again inserted into the slit
14
. This causes the substance
24
left in the slit
14
to cling back to the wafer
12
. The substance
24
, required in a certain process, can thus turn into a contaminant in a different process.
FIG. 23
is a schematic view explaining how contaminants can spread over the wafer
12
during semiconductor device production. In the setup of
FIG. 23
, a product
1
is supposed to be processed by first production equipment
26
alone in the normal course of production. In this example, the product
1
is shown processed by second production equipment
30
by human error after being processed by the first production equipment
26
. In such a case, a second substance
32
used inside the second production equipment
30
can be contaminated by a first substance
28
stuck to the wafer
12
in the first production equipment
26
.
In
FIG. 23
, a product
2
is supposed to be processed by the second production equipment
30
. If the second substance
32
has come to be contaminated by the first substance
28
as described above, the product
2
is polluted by the first substance
28
while being processed by the second production equipment
30
. In this manner, an error in the production flow of a single product can give rise to in-process contamination.
In the example of
FIG. 23
, a product
3
is supposed to be processed by the first production equipment
26
alone in the normal course of production. In this example, the product
3
is shown processed by the first production equipment
26
before being transferred by human error into a cassette that should be dedicated in use only to a process involving the second substance
32
. In such a case, the transferred wafer
12
is contaminated by the second substance
32
that came off the dedicated cassette. In this manner, an error in the movement of a cassette of a single product can trigger in-process contamination.
As outlined above, human error in conventional semiconductor device production processes can often result in contamination of products. What follows is a brief supplementary explanation of how such contamination can affect the characteristics of semiconductor devices.
FIG. 24
is an enlarged view of a gate portion and its surroundings in an MOS transistor. The MOS transistor
FIG. 24
has a gate insulating film
36
and a gate electrode
38
formed on a wafer
12
. The gate insulating film
36
includes an insulation-deteriorated portion
40
, i.e., a portion where a contaminant has deteriorated the quality of the film. Typical contaminants producing the insulation-deteriorated portion
40
are metals. Among the metals, particularly aluminum (Al) and copper (Cu) are liable to trigger high degrees of contamination due to large diffusion coefficients thereof. In
FIG. 24
, a voltage applied between the gate electrode
38
and the wafer
12
causes a large leak current
44
to flow through the insulation-deteriorated portion
40
. Once the insulation-deteriorated portion
40
is formed, the MOS transistor can no longer function with correct electrical characteristics.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to overcome the above and other deficiencies of the prior art and to provide a semiconductor device production management system that effectively prevents the diffusion of contaminants caused by human error.
It is another object of the present invention to provide a semiconductor device production method for producing high-quality semiconductor devices at high yield rates using the inventive production management method.
The above objects of the present invention are achieved by a production management system for managing production of semiconductor devices. The system includes usage rule storing means for storing usage rules on containers for accommodating wafers with regard to individual processes included in a reviewable process flow. The system also includes reviewable process flow checking means for checking whether the reviewable process flow complies with the usage rules.
The above objects of the present invention are achieved by a production management system for managing production of semiconductor devices. The system includes production line process flow storing means for storing a plurality of processes included in a production line process flow for use on a semiconductor device production line. The system also includes container condition storing means for storing usage rules on containers for accommodating wafers with regard to each of the processes included in the production line process flow. The system further includes usage rule supplying means for supplying the usage rules regarding the containers to either pieces of production equipment for executing the processes included in the production line process flow, or to devices installed close to the pieces of production equipment.
The above objects of the present invention are achieved by a semiconductor device production method for producing semiconductor devices by use of a production management method described above.
Other objects and further features of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings.
REFERENCES:
patent: 4974166 (1990-11-01), Maney et al.
patent: 5443346 (1995-08-01), Murata et al.
patent: 5694325 (1997-12-01), Fukuda et al.
patent: 6078845 (2000-06-01), Friedman
patent: 6-183524 (1994-07-01), None
Masinick Michael D.
McDermott & Will & Emery
Picard Leo
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