Substrate holding apparatus and a system using the same

A substrate holding apparatus includes a pump, serving as a suction source, a conveying chuck for holding a wafer substrate by suction, a connection arrangement, including parallel lines intermediate the connection arrangement, for conneting the pump to the chuck, and a valve arrangement including at least one valve provided in at least one of the parallel lines. By selecting one of the parallel lines by controlling opening/closing of these valves, the conductance of the connection line is adjusted, whereby the optimum suction pressure for the chuck is set.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a technique relating to holding, transfer and the 
like of a substrate by suction, which is used, for example, for 
manufacturing semiconductor devices. 
2. Description of the Related Art 
FIG. 6 illustrates a conventional apparatus for holding a semiconductor 
wafer by a vacuum suction method, which is used, for example, for a 
semiconductor-device manufacturing apparatus. In this substrate holding 
apparatus, conveying chuck 131 for holding wafer 141 by suction is mounted 
on a conveying mechanism having an X-stage 133 moving in the x-direction 
(the lateral direction in FIG. 6) and a Z-stage 134 moving in the 
z-direction (a direction perpendicular to the plane of FIG. 6). Wafer 141 
is transferred between conveying chuck 131, and wafer chuck 132 for 
holding wafer 141 by suction during an exposure operation. These 
components are housed within chamber 142 maintained under a reduced 
pressure. 
Conveying chuck 131 is connected to distributor 139 by connection line 135 
having first valve 137 at a midpoint thereof. Wafer chuck 132 is connected 
to distributor 139 by connection line 136 having second valve 138 at a 
midpoint thereof. Distributor 139 is connected to pump 140. 
Each of conveying chuck 131 and wafer chuck 132 holds and releases wafer 
141 by a suction operation of pump 140. Each of valves 137 and 138 is a 
three-way valve, which can switch between a first state in which each of 
conveying chuck 131 and wafer chuck 132 communicates with pump 140, 
respectively, and a second state in which each of conveying chuck 131 and 
wafer chuck 132 communicates with the atmosphere within chamber 142, 
respectively. 
An explanation will now be provided of a case in which wafer 141 is 
transferred from conveying chuck 131 to wafer chuck 132. First, in order 
to hold wafer 141 by conveying chuck 131 by suction, first valve 137 is 
maintained in the first state in which conveying chuck 131 communicates 
with pump 140, and pump 140 is operated to hold wafer 141 by suction by 
conveying chuck 131. At that time, second valve 138 is maintained in the 
second state in which wafer chuck 132 communicates with the atmosphere of 
chamber 142, so that the pressure within second vacuum line 136 equals the 
pressure of the atmosphere within chamber 142. 
Thereafter, by driving X-stage 133, wafer 141 held by conveying chuck 131 
by suction is moved onto the surface of wafer chuck 132. Then, by driving 
Z-stage 134, conveying chuck 131 is moved until wafer 141 contacts the 
surface of wafer chuck 132. When wafer 141 has contacted the suction 
surface of wafer chuck 132, second valve 138 is switched to the first 
state, whereby wafer 141 is held by suction by wafer chuck 132. That is, 
wafer 141 is held by suction by both conveying chuck 131 and wafer chuck 
132. Thereafter, first valve 137 is switched to the second state in which 
conveying chuck 131 communicates with the atmosphere of chamber 142. Thus, 
the holding force of conveying chuck 131 by suction disappears, and wafer 
141 is held by suction only by wafer chuck 132. Thereafter, by 
sequentially driving Z-stage 134 and X-stage 133, conveying chuck 131 is 
returned to the original position. Thus, the tranfer of wafer 141 to wafer 
chuck 132 is completed. 
While wafer 141 is held by wafer chuck 132, a circuit pattern is exposed 
and transferred onto wafer 141 by an exposure apparatus (not shown). 
Thereafter, by driving X-stage 133 and Z-stage 134, conveying chuck 131 is 
moved to the position of wafer chuck 132 in order to transfer wafer 141. 
This tranfer operation is inverse to the above-described transfer 
operation of wafer 141 from conveying chuck 131 to wafer chuck 132. 
The above-described conventional approach, however, has the following 
problems to be solved. 
(1) The minimum differential pressure necessary for holding the substrate 
by suction, i.e., the critical differential pressure dPL depends on the 
following items: 
1) The surface roughness of the holding surface of the substrate holding 
apparatus. 
2) The flatness of the holding surface of the substrate holding apparatus. 
3) The suction area of the holding surface of the substrate holding 
apparatus. 
When the substrate is held, transferred and conveyed by setting the suction 
pressure to the critical differential pressure dPL, the subtrate cannot be 
held and leaves the surface of the chuck if, for example, a part of the 
coated resist moves to the back of the substrate, or dust adheres to the 
suction surface. On the other hand, if the suction pressure is set to the 
maximum differential pressure, time is needed until the suction pressure 
reaches the set pressure, causing a decrease in the throughput of the 
operation. 
(2) If the substrate is conveyed at a high speed, the conveying speed and 
the acceleration until the speed reaches the conveying speed increase. 
Hence, it is necessary to prevent the substrate from dropping by 
increasing the differential pressure between the suction pressure of the 
conveying chuck and the pressure of the atmosphere of the chamber. On the 
other hand, when performing exposure using X-rays, it is necessary to 
transfer heat generated at a mask to a temperature-controlled wafer chuck. 
For that purpose, He (helium) gas is usually supplied between the mask and 
the wafer, and the wafer and the wafer chuck to increase the efficiency of 
heat conduction. If the differential pressure for the conveying chuck is 
increased as described above, the differential pressure for the wafer 
chuck is also increased. As a result, the degree of vacuum between the 
wafer and the wafer chuck increases, causing a reduction in the amount of 
He gas. The thermal contact resistance between the wafer and the wafer 
chuck thereby increases, causing a decrease in the efficiency of heat 
conduction. 
(3) When a plurality of chucks, such as the above-described conveying 
chuck, wafer chuck and the like, are provided, since the suction area, the 
surface roughness and the like of the substrate holding surface differ for 
each chuck, the suction force differs even if the same suction pressure is 
provided. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to overcome the above-described 
problems of the prior art. 
It is another object of the present invention to maintain both the 
reliability and throughput of an operation of holding and transferring a 
substrate at a high level. 
According to one aspect, the present invention which achieves these 
objectives relates to a substrate holding apparatus and an exposure 
apparatus including the same, comprising a suction source for providing 
suction, a holding mechanism for holding a substrate by suction provided 
from said suction source, a connection arrangement, including a plurality 
of parallel lines at a midpoint thereof, for connecting the suction source 
to the holding mechanism, a valve arrangement including at least one valve 
provided in at least one of the parallel lines, and a controller for 
adjusting the conductance of the connection arrangement by controlling 
opening/closing of the valve arrangement. 
According to another aspect, the present invention which achieves these 
objectives relates to a substrate holding apparatus and an exposure 
apparatus including the same, comprising a suction source for providing 
suction, a holding mechanism for holding a substrate by suction provided 
from the suction source, a connection line for connecting the suction 
source to the holding mechanism, the connection line comprising an 
adjustment mechanism for adjusting the conductance of the connection line 
and being provided intermediate the connection line, and an accumulator 
provided intermediate the connection line for assisting the adjusting 
mechanism in adjusting the conductance of the connection line. 
According to another aspect, the present invention provides a method of 
holding and exposing a substrate. The method includes the steps of 
providing a connection arrangement, including parallel lines intermediate 
the connection arrangement, for connecting a suction source to a holding 
mechanism, adjusting the conductance of the connection arrangement by 
controlling opening/closing of at least one valve provided in the parallel 
lines, holding the substrate by suction provided to the holding mechanism 
and exposing the held substrate. 
In yet another aspect, the present invention provides a method of holding 
and exposing a substrate. The method includes the steps of providing 
suction to a holding mechanism that holds a substrate by suction, 
providing a connection line for connecting the suction source to the 
holding mechanism, the connection line having an accumulator intermediate 
the connection line, adjusting the conductance of the connection line by 
using the accumulator and exposing the held substrate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 is a diagram illustrating the configuration of a semiconductor 
manufacturing system according to a first embodiment of the present 
invention. Main components are housed within low-pressure chamber 16 
maintained in an atmosphere of a predetermined reduced pressure. For 
example, He gas is supplied to low-pressure chamber 16. Both conveying 
chuck 1 and wafer chuck 2 can hold a wafer, serving as a semiconductor 
substrate, by suction. X-stage 3 moves conveying chuck 1 in the 
x-direction (the lateral direction in FIG. 1), and Z-stage 4 moves 
conveying chuck 1 in the z-direction (a direction perpendicular to the 
plane of FIG. 1). A substrate conveying mechanism including these stages 
transfers wafer 20 between a wafer cassette (not shown) for accommodating 
wafer 20 and wafer chuck 2. Wafer chuck 2 can be moved by conveying 
mechanism 13 between a wafer receiving position and an exposure position 
where an exposure apparatus 14 is installed, while holding wafer 20 by 
suction. A method of exposing and transferring a mask pattern onto a wafer 
by projecting the pattern onto the wafer using radiation energy, such as 
ultra-violet light, X-rays or the like, an exposure method in which a 
circuit pattern is directly drawn on a wafer using an electron beam, or 
the like is used as the exposure method of exposure apparatus 14. 
Conveying chuck 1 and wafer chuck 2 are connected to pump 10, serving as a 
vacuum suction source, via two vacuum lines 5 and 6 obtained by 
distributing the suction line of pump 10 by distributor 9, respectively. 
Pump 10 and distributor 9 are provided outside low-pressure chamber 16. 
First valve 7, which is a three-way valve, third valve 71 and fourth valve 
72 connected to two lines branched in parallel, and first vacuum sensor 11 
for detecting the pressure at the suction surface of conveying chuck 1 are 
successively provided in first vacuum line 5. Valves 71 and 72 are on-off 
valves having a simple mechanism. Second valve 8, which is a three-way 
valve, fifth valve 81, sixth valve 82 and seventh valve 83 connected to 
three lines branched in parallel, and second vacuum sensor 12 for 
detecting the pressure of the suction surface of wafer chuck 2 are 
successively provided in second vacuum line 6. Valves 81, 82 and 83 are 
on-off valves. 
The two parallel lines in which third valve 71 and fourth valve 72 are 
provided have different conductance values. The three parallel lines in 
which fifth valve 81, sixth valve 82 and seventh valve 83 are provided 
have different conductance values. By selecting one of these lines by 
controlling opening/closing of these valves, the conductance of the entire 
vacuum line can be changed. 
Main controller 17 controls the entire system, valve controller 18 controls 
opening/closing of the respective valves, and vacuum sensor 19 detects the 
pressure within low-pressure chamber 16, and maintains the atmosphere at a 
predetermined reduced pressure. 
Next, a description will be provided of the function of the system having 
the above-described configuration. A state in which conveying chuck 1 or 
wafer chuck 2 communicates with pump 10 by controlling first valve 7 or 
second valve 8, which is a three-way valve, respectively, is defined as a 
first state. A state in which conveying chuck 1 or wafer chuck 2 is 
released to the atmosphere within low-pressure chamber 16 is defined as a 
second state. 
By causing first valve 7 to assume the first state during a suction 
operation of pump 10 while opening at least one of third valve 71 and 
fourth valve 72, provided in parallel, a differential pressure with 
respect to the pressure of the atmosphere within low-pressure chamber 16 
is provided for conveying chuck 1, so that conveying chuck 1 can hold 
wafer 20 by suction. If first valve 7 is caused to assume the second 
state, the suction surface of conveying chuck 1 has the same pressure 
value as that within chamber 16, so that conveying chuck 1 cannot hold 
wafer 20 by suction. Similarly, by causing second valve 8 to assume the 
first state during a suction operation of pump 10 while opening at least 
one of fifth valve 81, sixth valve 82 and seventh valve 83, provided in 
parallel, a differential pressure with respect to the pressure of the 
atmosphere within low-pressure chamber 16 is provided for wafer chuck 2, 
so that wafer chuck 2 can hold wafer 20 by suction. If second valve 8 is 
caused to assume the second state, the suction surface of wafer chuck 2 
has the same pressure value as that of the atmosphere within chamber 16, 
so that wafer chuck 2 cannot hold wafer 20 by suction. 
In the present embodiment, the suction pressure for conveying chuck 1 is 
controlled for transferring and conveying operations of wafer 20 with 
respect to the wafer cassette, and transferring and conveying operations 
of wafer 20 with respect to wafer chuck 2 in the atmosphere of 
low-pressure chamber 16. The suction pressure for wafer chuck 2 is 
controlled for a transfer operation of wafer 20 in the atmosphere of a 
reduced pressure, a conveying operation of wafer 20 to an exposure 
position, and an exposure operation of wafer 20 at the exposure position. 
Optimum values of the suction pressure for the above-described respective 
operations are determined as set values. The following table illustrates 
an example of the optimum values of the suction pressure in the respective 
operations. 
TABLE 1 
__________________________________________________________________________ 
Optimum values of the suction pressure for the conveying chuck 
and the wafer chuck for respective operations. 
Optimum suction pressure 
Suction Conveying 
Wafer 
No. 
Operation 
force Effect chuck chuck 
__________________________________________________________________________ 
1 Conveyance 
Maximum 
Reliability 
P.sub.1 
P.sub.1W 
Transfer 
Critical 
Throughput 
(Differential 
(Differential 
pressure: 
pressure: 
80 Torr) 
50 Torr) 
2 Transfer 
Maximum 
Reliability 
P.sub.2 
P.sub.2W 
Transfer 
Critical 
Throughput 
(Differential 
(Differential 
pressure: 
pressure: 
100 Torr) 
70 Torr) 
3 Exposure 
Maximum 
Corrective 
-- P.sub.3W 
force (Absolute 
Exposure 
Critical 
Reduction of pressure: 
thermal contact 
70-80 Torr) 
resistance 
__________________________________________________________________________ 
In Table 1, the optimum values P.sub.1 and P.sub.2 of the suction pressure 
in conveying and transferring operations of conveying chuck 1 are 
determined in terms of the values of the differential pressure with 
respect to the pressure of the atmosphere. The optimum values P.sub.1W and 
P.sub.2W of the suction pressure in conveying and transferring operations 
of wafer chuck 2 are determined in terms of the values of the differential 
pressure with respect to the pressure of the atmosphere. The optimum value 
P.sub.3W of the suction pressure in an exposure operation is determined in 
terms of the absolute pressure. 
The values P.sub.1 and P.sub.1W of the suction pressure shown in No. 1 and 
the values P.sub.2 and P.sub.2W of the suction pressure shown in No. 2 are 
determined in terms of the differential pressure with respect to the 
pressure P.sub.a of the atmosphere. These values are present between the 
maximum differential pressure corresponding to the maximum suction force 
and the critical differential pressure corresponding to the critical 
suction force for holding the wafer by suction. When the suction pressure 
is set to the pressure corresponding to the maximum suction force, 
reliability in the holding of the substrate by suction increases, but a 
long time is needed until the suction pressure of the suction surface for 
the wafer reaches the pressure corresponding to the maximum suction force, 
causing a decrease in the throughput of a transfer operation of the 
substrate. On the other hand, when the suction pressure is set to the 
critical differential pressure for holding the substrate, the throughput 
increases, but reliability in the holding of the substrate by suction 
decreases. Accordingly, these optimum values P.sub.1, P.sub.1W, P.sub.2 
and P.sub.2W of the suction pressure are determined to have different 
values for conveying chuck 1 and wafer chuck 2 so that both the 
reliability and throughput are sufficiently satisfied, in consideration of 
the area, surface roughness and the like of the suction surface for the 
wafer. 
The optimum value P.sub.3W of the suction pressure for wafer chuck 2 in an 
exposure operation shown in FIG. 3 is determined in terms of the absolute 
pressure. As for the suction force for the wafer during an exposure 
operation, a large differential pressure with respect to the pressure of 
the atmosphere is preferable from the viewpoint of the corrective force 
for the plane of wafer 20 on the suction surface for the wafer, but a 
small differential pressure is preferable in order to reduce the thermal 
contact resistance of the suction surface. In the present embodiment, the 
optimum value P.sub.3W of the suction pressure is determined to be 70-80 
Torr in terms of the absolute pressure for the pressure P.sub.a of the 
atmosphere in consideration of a balance between the above-described 
corrective force and thermal contact resistance. 
The setting of the optimum suction pressure necessary for each operation of 
conveying chuck 1 is realized by monitoring the pressure signal of first 
vacuum sensor 11 by main controller 17, instructing opening/closing of 
valves 71 and 72 to valve controller 18, and selecting one of the two 
lines having different conductance values. Similarly, the setting of the 
optimum suction pressure necessary for each operation of wafer chuck 2 is 
realized by monitoring the pressure signal of second vacuum sensor 12 by 
main controller 17, instructing opening/closing of valves 81, 82 and 83 to 
valve controller 18, and selecting one of the three lines having different 
conductance values. 
Next, a description will be provided of the details of the operation of the 
system of the present embodiment. FIG. 2 illustrates changes in the 
suction pressure in the respective operations. In FIG. 2, if the value of 
the critical differential pressure necessary for holding wafer 20 by 
suction in a reduced pressure P.sub.a of the atmosphere (for example, 
several hundreds of Torr) is represented by dPL, wafer 20 can be held by 
suction when the suction pressure is equal to or less than the pressure 
P.sub.dPL corresponding to the critical differential pressure. 
It is assumed that in the initial state, both valves 7 and 8 assume the 
second state, that is, they are opened to the pressure of the atmosphere, 
fourth valve 72, fifth valve 81 and seventh valve 83 are closed, and third 
valve 71 and sixth valve 82 are opened. In this state, the suction 
surfaces of conveying chuck 1 and wafer chuck 2 are exposed to the same 
pressure as the pressure P.sub.a of the atmosphere. 
First, by driving X-stage 3, conveying chuck 1 is moved in the direction of 
the wafer cassette provided within low-pressure chamber 16, and an 
operation of transferring wafer 20 from the wafer cassette is performed. 
Pump 10 is caused to assume the suction state, first valve 7 is switched 
to the first state, fourth valve 72 is opened, and third valve 71 is 
closed. Thus, conveying chuck 1 communicates with pump 10, and holds wafer 
20 by suction. The conductance value of the line is designed so that the 
optimum suction pressure P.sub.2 (differential pressure of 100 Torr) shown 
in the above-described Table 1 is obtained when third valve 71 is closed 
and fourth valve 72 is opened. While wafer 20 is held by suction by 
conveying chuck 1 with the optimum suction pressure P.sub.2, conveying 
chuck 1 is moved by driving X-stage 3 in order to transfer the held wafer 
20 to wafer chuck 2. During this transfer operation, the conductance value 
of the line is changed by opening third valve 71 and closing fourth valve 
72 so that the suction pressure of conveying chuck 1 equals the optimum 
suction pressure P.sub.1 (differential pressure of 80 Torr, as shown in 
Table 1). 
When wafer 20 has been conveyed onto the suction surface of wafer chuck 2 
by driving X-stage 3, wafer 20 held by conveying chuck 1 by suction is 
moved in the z-direction by driving Z-stage 4 until wafer 20 contacts the 
suction surface of wafer chuck 2. 
When wafer 20 has contacted the suction surface of wafer chuck 2, second 
valve 8 is switched to the first state, seventh valve 83 is opened, fifth 
valve 81 and sixth valve 82 are closed, and wafer 20 is held by suction by 
wafer chuck 2. The conductance value of the line is designed so that the 
suction pressure of wafer chuck 2 at that time equals the optimum suction 
pressure T.sub.2W (differential pressure of 70 Torr) shown in the 
above-described Table 1. In this state, wafer 20 is held by suction by 
both conveying chuck 1 and wafer chuck 2. When the detection value of 
second vacuum sensor 12 has reached the pressure P.sub.2W, first valve 7 
is switched to the second state to release the holding of wafer 20 by 
suction by conveying chuck 1, so that wafer 20 is held by suction only by 
wafer chuck 2. Thereafter, by driving Z-stage 4 and X-stage 3, conveying 
chuck 1 is returned to the initial position. 
Subsequently, wafer chuck 2 is moved to a predetermined exposure position 
by driving mechanism 13. During this movement, the optimum suction 
pressure of wafer chuck 2 is set to the value P.sub.1W (differential 
pressure of 50 Torr, as shown in Table 1) for an exposure operation by 
selecting the conductance value of the line by opening sixth value 82 and 
closing seventh valve 83 and fifth valve 81. 
When wafer 20 has reached the exposure position, the conductance value of 
the line is set so that the suction pressure of wafer chuck 2 equals the 
optimum suction pressure T.sub.3W (absolute pressure of 70-80 Torr, as 
shown in Table 1) by opening fifth valve 81 and closing sixth valve 82 and 
seventh valve 88. In this state, a circuit pattern is exposed on wafer 20 
by exposure apparatus 14. 
After the completion of the exposure for wafer 20, wafer 20 is transferred 
to conveying chuck 1, and is accommodated within the wafer cassette by 
conveying chuck 1 by performing an operation which is reverse to the 
above-described operation sequence. 
Although the system of the above-described embodiment is always maintained 
in an atmosphere of a reduced pressure, the system may be maintained at 
atmospheric pressure. 
In the above-described embodiment, each of a plurality of parallel lines 
having different conductance values has a valve, and the conductance value 
of the entire vacuum line is set by selecting one of the lines. However, 
the following modifications may be considered. 
(1) The conductance value of the entire vacuum line is set by switching 
between state (a), in which only one of a plurality of valves is opened, 
and state (b), in which the plurality of valves are simultaneously opened. 
The conductance value of each line is designed so that the respective 
optimum values of the suction pressure set in Table 1 are obtained for 
states (a) and (b). 
(2) A valve is not provided in one of a plurality of parallel lines so that 
the line is always opened. The conductance value of the entire vacuum line 
is set by opening and closing remaining valves. The conductance value of 
each line is designed so that the respective optimum values of the suction 
pressure set in Table 1 are obtained in a plurality of states obtained by 
opening and closing the valves. 
Second Embodiment 
FIG. 3 is a diagram illustrating the configuration of a semiconductor 
manufacturing system according to a second embodiment of the present 
invention. Basically, the configuration of the present embodiment is 
obtained by adding some components to the configuration of the embodiment 
shown in FIG. 1. Hence, the same reference numerals as those shown in FIG. 
1 represent the same or equivalent components. The optimum values of the 
suction pressure in respective operations in the present embodiment are 
the same as those shown in the above-described Table 1 and in FIG. 2. 
Four vacuum lines branched from distributor 9 include valves 41 through 44 
and accumulators 21 through 24, respectively. These components are 
provided outside low-pressure chamber 16. Accumulators 21 through 24 
include vacuum sensors 31 through 34 for detecting corresponding pressure 
values, respectively. The outputs of vacuum sensors 31 through 34 are fed 
back, and the corresponding valves 84 through 87 are always controlled to 
be opened/closed so that accumulators 21 through 24 always have the 
predetermined pressure values shown in the above-described Table 1, 
respectively. The pressure values of accumulators 21 through 24 are 
maintained at values P.sub.2, P.sub.1, P.sub.1W and P.sub.2W, 
respectively. 
The conductance value of the vacuum line is designed so that the pressure 
of wafer chuck 2 equals the optimum pressure P.sub.3W for an exposure 
operation when accumulator 23 has the pressure value P.sub.1W, fifth valve 
81 is opened, and sixth valve 82 and seventh valve 83 are closed. 
The opening/closing control of the respective valves in each operation 
sequence of the system of the present embodiment is the same as that in 
the above-described embodiment shown in FIG. 2. In the present embodiment, 
however, since an accumulator is provided in each line, the suction 
surface of conveying chuck 1 or wafer chuck 2 can instantaneously have the 
pressure value of the accumulator, i.e., the optimum suction pressure when 
the corresponding valve is opened. Hence, the throughput of the system can 
be improved compared with that of the above-described embodiment. 
Third Embodiment 
Next, a description will be provided of an embodiment relating to a 
semiconductor-device manufacturing method which utilizes the 
above-described semiconductor manufacturing system. FIG. 4 illustrates a 
flowchart for manufacturing semiconductor devices (semiconductor chips of 
IC's (integrated circuits), LSI's (large-scale integrated circuits) or the 
like, liquid-crystal panels, CCD's (charge-coupled devices), or the like). 
In step 1 (circuit design), circuit design of semiconductor devices is 
performed. In step 2 (mask manufacture), masks on which designed circuit 
patterns are formed are manufactured. In step 3 (wafer manufacture), 
wafers are manufactured using a material, such as silicon or the like. 
Step 4 (wafer process) is called a pre-process, in which actual circuits 
are formed on the wafers by means of photolithography using the 
above-described masks and wafers. The next step 5 (assembling) is called a 
post-process, which manufactures semiconductor chips using the wafers 
manufactured in step 4, and includes an assembling process (dicing and 
bonding), a packaging process (chip encapsulation), and the like. In step 
6 (inspection), inspection operations, such as operation-confirming tests, 
durability tests and the like of the semiconductor devices manufactured in 
step 5, are performed. The manufacture of semiconductor devices is 
completed after passing through the above-described processes, and the 
manufactured devices are shipped (step 7). 
FIG. 5 illustrates a detailed flowchart of the above-described wafer 
process. In step 11 (oxidation), the surface of the wafer is oxidized. In 
step 12 (CVD), an insulating film is formed on the surface of the wafer. 
In step 13 (electrode formation), electrodes are formed on the surface of 
the wafer by vacuum deposition. In step 14 (ion implantation), ions are 
implanted into the wafer. In step 15 (resist process), a photosensitive 
material is coated on the wafer. In step 16 (exposure), the circuit 
pattern on the mask is exposed and printed on the wafer by the 
above-described semiconductor manufacturing system. In step 17 
(development), the exposed wafer is developed. In step 18 (etching), 
portions other than the developed resist image are etched off. In step 19 
(resist separation), the resist which becomes unnecessary after the 
completion of the etching is removed. By repeating these steps, a final 
circuit pattern made of multiple patterns is formed on the wafer. By using 
the manufacturing method of the present embodiment, it is possible to 
manufacture semiconductor devices with high productivity. 
Except as otherwise disclosed herein, the various components shown in 
outline or in block form in the figures are individually well known and 
their internal construction and operation are not critical either to the 
making or using of this invention or to a description of the best mode of 
the invention. 
While the present invention has been described with respect to what is 
presently considered to be the preferred embodiments, it is to be 
understood that the invention is not limited to the disclosed embodiments. 
To the contrary, the present invention is intended to cover various 
modifications and equivalent arrangements included within the spirit and 
scope of the appended claims. The scope of the following claims is to be 
accorded the broadest interpretation so as to encompass all such 
modifications and equivalent structures and functions.