JP3291811B2 - Projection exposure equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reduction projection exposure apparatus for a semiconductor manufacturing apparatus, and more particularly to a projection exposure apparatus capable of improving positioning accuracy.

[0002]

2. Description of the Related Art A conventional exposure apparatus is disclosed in JP-A-62-939.
As described in Japanese Patent Publication No. 36, in order to make the refractive index of air in the space between the wafer stage portion and the projection optical portion uniform, a temperature-controlled airflow is sent to the wafer stage portion. There is a type provided with a single temperature control system.
In such a single-system temperature control system, the magnitude of the temperature rise of the airflow varies depending on the path of the flowing airflow, so that many airflows of different temperatures enter the wafer stage portion, and various movements of the stage occur. Therefore, the ambient temperature of the stage cannot be kept constant. For this reason, temperature fluctuation occurs on the stage and the wafer, and the positioning accuracy cannot be stabilized.

Therefore, as described in Japanese Patent Application Laid-Open Nos. Hei 4-22118 and Hei 2-199814,
Each section of the exposure apparatus is divided into a plurality of sections, and a section for supplying a temperature-controlled airflow to each section, and an individual chamber locally provided on a stage section and the like, and a section for supplying a temperature-controlled airflow to the chamber A multi-system temperature control system is known.

[0004]

However, in the above prior art, no consideration is given to the delivery of the wafer to the stage from outside the exposure apparatus. Therefore, in order to control the temperature in the stage unit by transferring the wafer to the stage unit, there is a problem that a great amount of time is required for the temperature adjustment.

In an exposure apparatus having a multi-system temperature control system, there is a method of adjusting the temperature by trial and error at the time of adjusting the stepper. Had been taken. Therefore, it takes time to adjust, and by adjusting the temperature of one place,
An imbalance in temperature elsewhere resulted in an inefficient adjustment.

SUMMARY OF THE INVENTION An object of the present invention has been made based on the above-mentioned problems, and an object of the present invention is to provide a projection exposure apparatus capable of stabilizing the temperature of a stage and shortening the time for adjusting the temperature. To provide.

[0007]

The purpose of the present invention, in order to solve the problems] includes a stage of the wafer can Me-position-decided to be exposed, the projection exposure and a chamber that can be supplied to a plurality of air flow the temperature can be controlled within in the apparatus, the surface of the stage where the stage is mounted, only setting the vestibule of the wafer to the stage, the temperature controlled air flow, provided the air flow supply unit for supplying to the stage with a temperature difference, the wafer by providing the exhaust unit to the stage portion other than the vestibule, it is achieved.

[0008] Also, the object of the present invention, a stage that the wafer can Me-position-decided to be exposed, and a configuration with a chamber so that it can supply a plurality of air flow the temperature can be controlled within
A projection exposure apparatus comprising: a first airflow supply unit for supplying a temperature-controlled airflow to a space in the chamber to cool the entire apparatus into the chamber; and a second airflow supply unit for supplying a temperature-controlled airflow to a stage. And airflow supply means of
Temperature detecting means for detecting respective temperature of the airflow from said first air flow supply means and the second air flow supply means is provided, based on the detection signal of the temperature detecting hand stage, the first air flow supply means by providing control means for controlling the first air flow supply means and the second air flow supply means to provide a temperature difference to the airflow and the second air flow supply hand stage or these airflow from it is achieved .

[0009]

[Function] By applying a temperature difference to the airflow flowing into the stage
Supply. As a result, the temperature within the movable range of the stage
Become uniform. That is, the airflow supply means to the stage section
Airflow is provided. In the chamber, cool the entire equipment.
To be sent. Cooling the entire unit
Air flow and the air flow for the stage section flow into the stage section
I do. The temperature of these multiple airflows also has a temperature difference.
Supplied. This stabilizes the temperature of the stage
Adjustment can be performed efficiently.
Wear.

[0010]

FIG. 1 is a plan view showing an embodiment of a projection exposure apparatus according to the present invention. The lower part of FIG. 1 is the front face of the apparatus.
FIG. 2 is a side view of the stage section of the projection exposure apparatus shown in FIG. 1, and the right side of FIG.

In FIG. 1, a main body 1 of a projection exposure apparatus comprises:
It is stored in the thermal clean chamber 2. The chamber 2 is a storage room 3 for storing the main body 1 of the projection exposure apparatus.
And a machine room 4 containing a machine for controlling the temperature by supplying air thereto.

The stage unit 5 is on a surface plate on which the stage 6 moves.
It is at the load point A, and at the time of exposure, is around the point B below the reduction lens 7 as shown in FIG. The stage section 5 is partitioned at the rear by a partition plate 8 and at right and left by partition plates 9 and 10, and its front portion is opened for taking in and out of a wafer. Thus, there is no airflow from the left, right, and rear to the stage 5, but airflow enters from the front.

A duct 12 connected to a return duct port 11 for returning air in the storage room of the chamber 2 to the machine room.
And a duct 13 for returning air from the stage section 5 are connected to the machine room 4. The air passing through the ducts 12 and 13 is sucked by the blower 14. The air leaving the blower 14 enters the cooler 15 together with the outside air. Cooler 1
After the airflow temperature has been lowered in 5, the air leaving the air enters air temperature controllers 16 and 17. Air temperature controller 16,1
At 7, the temperature of the air passing therethrough is adjusted. The air temperature adjusters 16 and 17 are respectively provided with blowers 18 and 19
Connected to. The air discharged from the blower 18 enters the side flow filter 20 at the boundary between the machine room 4 of the chamber 2 and the stepper storage room 3, and enters the storage room 3 through the filter 20. The air exiting the blower 19 passes through the duct 21 and passes through the air curtain filter 2 in the stage 5.
2 and 23, and enter the filter 24 located in front of the stage 5 as shown in FIG.

Immediately after the air flow outlets of the filters 20 and 23, temperature sensors 25 and 26 are provided, respectively.
The signals ts1 and ts2 of the temperature sensors 25 and 26 are input to temperature controllers 27 and 28, respectively. The temperature control devices 27 and 28 output a signal pp for controlling the temperature from this signal.
1 and pp2, and these signals pp1 and pp2 are input to the air temperature regulators 16 and 17, respectively.

The above-mentioned temperature controllers 27 and 28 operate the air temperature regulators so that the airflow temperatures at the positions of the temperature sensors 25 and 26 become the temperature set values preset in the temperature controllers 27 and 28, respectively. 16 and 17 are controlled. The airflow whose temperature is controlled by the air temperature controller 16 passes through the side flow filter 20 and flows into the stepper storage chamber 3 toward the entire apparatus. On the other hand, the airflow that has passed through the air temperature controller 17 enters the air curtain filters 22 and 23 and the filter 24 above and in front of the stage 5, and is blown toward the stage 5.

FIG. 3 shows the air temperature controllers 16, 1 shown in FIG.
7 shows the configuration of the air temperature regulators 16, 1
A cooler 29 is provided upstream of 7. The cooler 29 includes a compressor 30, a condenser 31, an expansion valve 32, and an evaporator 33.

In this figure, a refrigerant is compressed by a compressor 30,
After condensing in the condenser 31, the evaporator 3 passes through the expansion valve 32.
Enter 3. This evaporator 33 lowers the temperature of the airflow. The refrigerant that has taken heat here enters the compressor 29 and forms a refrigeration cycle. In the condenser 31, the refrigerant is condensed by the cooling water cw. The airflow passes through the evaporator 33 to lower the temperature, and the air temperature controllers 16 and 17
to go into.

FIG. 4 shows another example of the cooler 29 used in the present invention. In this case, the cooling water cw directly exchanges heat with the airflow. As described above, the cooler 29 is used for temporarily lowering the temperature of the airflow and controlling the airflow temperature with the air temperature regulators 16 and 17 connected to the next stage. Any means for lowering may be used.

FIG. 5 shows a temperature control device 2 constituting the present invention.
7 shows a configuration diagram of the temperature control devices 27 and 2;
Reference numeral 8 may be the same control configuration, and controls each system by changing the set temperature and the value of the parameter of the control system. These temperature control devices 27 and 28 perform various calculations.
A U unit 34, a memory unit 35 for storing setting values and the like,
It comprises a display unit 36, an input unit 37, an interface unit 38 for the temperature sensors 25 and 26, an interface unit 39 for instructing an operation amount, and a triac 40. The air temperature regulators 16 and 17 are composed of heating elements, and the amount of heat generated is controlled by powers pp1 and pp2 from a power supply 41 controlled by a triac 40.

The above-mentioned temperature controllers 27 and 28 evaluate the results of the SWA (statistical process wafer alignment) process used in alignment performed by the controller (not shown) of the projection exposure apparatus, that is, the center of the wafer. A function of calculating a temperature set value based on the error amount is also provided.

FIG. 6 is a block diagram of a temperature control system according to the present invention.
The signal of 26 is sent to the CPU unit 3 via the interface unit 38.
4 and is converted into temperature information. In the ERR section 42 shown in FIG. 6, the difference between this information and the temperature set values s1 and s2 is obtained and becomes an error signal. In the PID unit 43, a control signal is calculated from the error signal by a PID control system, and PW
In the M section 44, the control amount is converted into a pulse width modulated signal, and through the interface section 39 and the triac 40, the amount of heat generated by the heating elements of the air temperature regulators 16 and 17 is controlled, and the temperature of the airflow is set to a temperature set value. Control so that The amount of control by such a temperature control system is not limited to execution by pulse width modulation, but may be any means capable of changing the amount of heat generated in accordance with a command value from the PID control system.

Next, the principle of air temperature control in the apparatus of the present invention will be described with reference to FIG. FIG. 7 is a simplified representation of the apparatus of the present invention shown in FIG. In this figure, it is assumed that the flow is constant and the temperature is balanced by the mixing of the gas flows. At this time, the air flow coming flows into the stage unit 5, the temperature t _a of the air curtain filter 2
And 2 and 23, and those air supply from the filter 24 of the temperature t _b, it is to that air supply from the side flow filter 20 of the temperature t _s. Since there is no inflow from the left and right, it is stated that there is an inflow of the side flow airflow only from the front.
Therefore, it is assumed that the following airflow flows into the stage unit per unit time.

From the front of the stage 5, the temperature t ₂ = t _s + Δt
_2, the air flow blown out from the side flow filter 20 of the air chamber temperature _{t b = t a + Δt b} , the volume V _b of the airflow the air curtain of the volume V ₂ temperature t _a, the airflow filter 24 having a volume V _a is the exposure apparatus Usually, the temperature rises due to the temperature rise of the atmosphere due to the heat generation of. Δt ₂ is the temperature rise while such airflow is moving. Further, the air flow temperature t _a is the air supply from the air curtain filter 22 and 23 are under the control of the temperature in the filter 24 outlet. Since this air flow is very close to the stage 5, this temperature rise can be ignored.

However, the airflow from the filter 24 flows through the same airflow that is supplied to the air curtain, so that there is a temperature change Δt _b before it reaches the stage 5. However, the temperature rise of these airflows is only a few degrees,
It is assumed that the density change of the airflow can be ignored.

At this time, the average temperature t _{c in the} vicinity B immediately below the lens, which is balanced by the mixing of the air flows in the stage 5, can be considered as follows.

[0026]

(Equation 1)

[0027] Here, being equal ambient temperature in the vicinity of A and the lens lower B load points transfer the wafer, since the movement range of the wafer stage is considered constant temperature, the temperature t ₂ and t _c near the load point Assume equal.

[0028] _{t c = t 2 = t s} + Δt 2 ............................................................... formula, from the equation, the relationship between t _a and t _s is the next As shown.

[0029]

(Equation 3)

At this time, the filter 2 in the upper part in front of the stage
The inflow from No. 4 does not drift in the space like the airflow from the side flow filter 20, and is considered to be an inflow of a constant volume at a relatively stable temperature. Therefore, the contribution of Δt _b is considered to be constant.

Therefore, the only variation factor is Δt _2, and the stability of the equilibrium point depends on Δt ₂ .

In other words, since the condition under which the temperature of the stage section 5 becomes uniform is the equation, the temperature t _s of the side flow airflow is expressed by the following equation.
By setting in advance the temperature difference between the air curtain stream temperature t _a in the stage 5, can be made uniform temperature of the stage 5. Actually, since the diffusion of the airflow is more complicated, it cannot be said that it is a simple difference shown by the equation. However, by making the temperature difference while checking the temperature of the stage section 5, the optimum airflow can be obtained. Temperature difference can be set.

Next, a method for determining that the ambient temperature of the stage section 5 in the projection exposure apparatus has become constant will be described. For this, a temperature sensor may be used, but here, the SWA (Statis) used for the above-described alignment is used.
The case where tic Wafer Alignment (statistical processing wafer alignment) processing is used will be described. This SWA processing is
The statistical processing of the alignment results of a large number of chips specified at arbitrary positions in the wafer is used to calculate the error amount (offset) at the center of the wafer. In this embodiment, the SWA processing is performed by the projection exposure apparatus. Instructed by a control device (not shown). At the time of temperature adjustment, attention is paid to the offset, which is the amount of error at the center of the wafer. One SW
In process A, many chips on the wafer are aligned,
As a whole, one set of XY offset values is obtained.

In this process, one stage is completed by the stage 6 receiving the wafer at the load point A, going under the lens, aligning a plurality of chips, and stopping at a certain standby position. Further, the second and subsequent SWA processes are started from this standby position.

At this time, the wafer and the stage 6 move to the load point A position, the position of each chip under the lens B, and the standby position. Further, in the next SWA process, the movement of each chip from the standby position to the position under the lens and then to the standby position is repeated. For this reason, it is exposed to the ambient temperature at the load point A, the ambient temperature at the position of each chip under the lens B, and the ambient temperature at the standby position.
Therefore, if there is a temperature difference between these ambient temperatures, the wafer or the stage 6 is thermally deformed.

By the SWA process, this thermal deformation is reduced by SW
It appears as a change in the offset at the center of the wafer in the A process. Therefore, when the SWA process is repeated n times,
Until the amount of variation of the offset value falls within a specified value, a temperature difference may be provided between the side flow and the airflow of the air curtain so as to eliminate the temperature difference between the positions.

FIG. 8 is a flowchart showing a method of adjusting the airflow temperature difference in the projection exposure apparatus of the present invention.
First, the temperature of the side flow from the side flow filter 20 and the temperature of the air curtain from the air curtain filters 22 and 23 are set to the same value (step 8).
0).

Next, SWA processing is performed in accordance with an instruction from the control unit of the projection exposure apparatus in the state described above (step 8).
1). The results of the SWA processing are stored in the temperature control devices 27 and 28.
Judge whether the: SWA value becomes smaller or: SWA
Whether the value increases: It is determined whether the change is within a specified value (step 82). And in the case of (step 83)
, The temperature set value of the side flow airflow is lowered by Δt (step 84). In the case of (step 85)
, The temperature set value of the side flow airflow is increased by Δt (step 86).

The value for changing the temperature set value varies depending on the degree of the change, but may be a value of about 0.1 to 0.4 degrees.

Thereafter, the SWA process is performed again to make a determination (step 82). As a result, if not, the change value is changed to a smaller value than before. In this way, when the temperature is set, a time is left for stabilizing the apparatus while keeping the temperature set (steps 87 and 88).

Thereafter, the SWA process is further performed, and if so, the variation amount indicating the change is within the specified value, and the adjustment ends. The specified value may be a value that is a fraction of the required alignment accuracy. For example, 0.5 μm
If the case is for a process, the alignment accuracy is 0.
It is about 1 μm, and a fraction of 0.02 μm can be set as the specified value.

Although the above-described change of the temperature set value has been described with reference to an example in which the temperature of the side flow airflow is changed, the temperature of the air curtain airflow may be changed while the temperature of the sideflow airflow is kept constant. In this case, the air curtain airflow temperature may be increased by Δt in the case of, and the air curtain airflow temperature may be decreased by Δt in the case of.

In this way, by adjusting the set values of the air curtain airflow temperature and the side flow airflow temperature, the adjustment time can be reduced.

This adjustment method is applicable not only to the present embodiment but also to other devices having a plurality of temperature control systems.
For example, as shown in FIG. 9, in a device having a stage unit in a closed state, a method may be considered in which a door 92 is provided on a wall 91 of a closed room for delivery of a wafer, and the door 92 is opened and closed. . In this case, the setting of the ambient temperature T1 in the stage unit 5 and the ambient temperature T2 outside the stage unit 5 needs to be adjusted because expansion and contraction due to the temperature due to the wafer W going in and out is eliminated. The present invention can be directly applied to this adjustment.

Alternatively, as shown in FIG. 10, a system in which a dedicated room 100 is provided and delivered is also conceivable.
In this case, the present invention can be applied to the setting of the ambient temperature T1 in the stage section 5 and the ambient temperature T2 in the dedicated room 100. Or, the same applies to the adjustment of the outside atmosphere temperatures T3 and T2.

In this adjustment, the function of the detection device used can be easily confirmed. Further, the same confirmation is performed not only at the adjustment stage of the device but also at the time of use of the device, whereby the stability is improved. There is an effect that the nature can be maintained.

FIG. 11 shows another embodiment of the apparatus of the present invention. In this figure, the same reference numerals as those in FIG. 1 denote the same parts. In this embodiment, a projection exposure apparatus controller 110 for controlling the projection exposure apparatus body 1 and temperature controllers 27 and 28 are provided.
And a higher-level control device 111 for supervising them. First, the higher-level control device 111 inputs the initial temperature set value to the temperature control devices 27 and 28, and sends an adjustment start signal st to the projection exposure device control device 110. As a result, the projection exposure apparatus controller 110 controls the projection exposure apparatus to execute the SWA process. Thereafter, the host control device 111 sends the SWA
The processing result sv is received, the value is determined based on the adjustment method described above, and new temperature set values s1 and s2 are instructed to the temperature control devices 27 and 28. In addition, the current temperature information p1, p
2 is received and it is determined whether there is any abnormality. Such a function is provided by the projection exposure apparatus controller 110 or the temperature controller 2
7 or 28.

[0048] In the above embodiment, is provided on the front of the device portion for delivering the wafer to the stage unit 5, it is also possible to transfer in the side of the device. In this case, the side is opened and the front is closed.

The temperature sensors 25 and 26 are installed at locations where they flow out in a laminar flow state, such as the filters 20 and 23, and have better temperature controllability. The sensor 26 provided at the outlet of the filter 23
It is also possible to provide at the air flow outlet.

The filter 2 above the stage 5
4 can also be supplied from the system of the blower 18 . In this case, the sensor 2 provided at the outlet of the filter 20
5 can be provided in the filter 24.

Note that the filter 2 above the stage section
The same effect can be obtained even if 4 is installed before the stage section 5 or on the left and right.

In the above-described embodiment, the wafer transfer section on the stage is provided on the side surface of the stage section, but transfer from the upper surface thereof is also possible.

[0053]

According to the present invention, the wafer can be transferred while the stage is open, so that the structure is simple and the reliability of the entire apparatus can be improved. Further, the temperature of the stage can be stably maintained, and the adjustment time for setting the temperature can be shortened.

[Brief description of the drawings]

FIG. 1 is a plan view showing a configuration of an embodiment of a projection exposure apparatus of the present invention.

FIG. 2 is a side view of a stage section constituting one embodiment of the projection exposure apparatus of the present invention shown in FIG.

FIG. 3 is a diagram showing a configuration of a cooler, an air temperature adjuster and a blower which constitute one embodiment of the projection exposure apparatus of the present invention shown in FIG.

FIG. 4 is a view showing another example of a cooler constituting one embodiment of the projection exposure apparatus of the present invention shown in FIG.

FIG. 5 is a diagram showing a configuration of a temperature control device constituting one embodiment of the projection exposure apparatus of the present invention shown in FIG. 1;

6 is a control block diagram of the temperature control device shown in FIG.

FIG. 7 is a configuration diagram of a stage section for explaining temperature adjustment in the embodiment of the projection exposure apparatus of the present invention shown in FIG.

FIG. 8 is a flowchart showing a temperature control operation of the projection exposure apparatus according to one embodiment of the present invention.

FIG. 9 is a side view showing another example of the stage section constituting the projection exposure apparatus of the present invention.

FIG. 10 is a side view showing still another example of the stage section constituting the projection exposure apparatus of the present invention.

FIG. 11 is a plan view showing the configuration of another embodiment of the projection exposure apparatus of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Projection exposure apparatus main body, 2 ... Chamber, 3 ... Storage room, 4
... machine room, 5 ... stage section, 6 ... stage, 7 ... reduction lens, 11 ... return duct, 12, 13 ... duct, 1
4 ... Blower, 15 ... Cooler, 16, 17 ... Air temperature controller, 18, 19 ... Blower, 20 ... Side flow filter, 22,23 ... Air curtain filter, 24 ... Filter, 25,26 ... Temperature sensor, 27 , 28 ... temperature control device.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Ryuichi Funatsu 882 Ma, Katsuta-shi, Ibaraki Hitachi, Ltd. Measuring Instruments Division (56) References JP-A-2-199814 (JP, A) JP-A-3 -97216 (JP, A) JP-A-3-129720 (JP, A) JP-A-4-22118 (JP, A) JP-A-5-129175 (JP, A) (58) Fields investigated (Int. . ⁷ , DB name) H01L 21/027 G03F 7/20

Claims (3)

(57) [Claims] A stay capable of positioning a wafer to be exposed.
And multiple air flows that can be temperature controlled can be supplied inside.
Exposure apparatus having a chamber configured as described above.
Chamber to cool the entire system.
A first airflow supply for supplying a temperature-controlled airflow to a space inside the chamber.
Supply means and a second means for supplying a temperature-controlled airflow to the stage.
2 airflow supply means, wherein the first airflow supply means and
Detects the temperature of the airflow from the second airflow supply means
Temperature detecting means for detecting the temperature from the temperature detecting means.
Signal and position information for wafer or chip alignment
Based on the airflow from the first airflow supply means and the
Before giving a temperature difference to the airflow from the airflow supply means 2
Controlling the first airflow supply means and the second airflow supply means;
A projection exposure apparatus comprising control means. 2. The projection exposure apparatus according to claim 1, wherein
A projection exposure apparatus, wherein a filter for blowing fresh airflow to a stage is provided above, in front of, or right and left of the stage. 3. The projection exposure apparatus according to claim 2 , wherein
A projection exposure apparatus, wherein the temperature detecting means is provided at the filter outlet.