JP3526162B2 - Substrate holding device and exposure device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate holding device and an exposure device of an exposure device for exposing a substrate such as a wafer for manufacturing a semiconductor.

[0002]

2. Description of the Related Art In recent years, circuit patterns have been miniaturized in order to improve the degree of integration and operating speed of solid-state elements such as LSI. In the circuit pattern formation in the process of manufacturing these LSIs, a reduction projection exposure apparatus in which the exposure light source is vacuum ultraviolet is widely used. In this case, the resolution is the exposure wavelength λ
Since it depends on the numerical aperture NA of the projection optical system, the resolution limit has been improved by increasing the numerical aperture NA. However, due to the reduction of the depth of focus (DOF) and the difficulty of the refraction optical system design / manufacturing technology, the resolution limit is approaching. Therefore, the exposure wavelength λ is shortened to improve the resolution. For example, i-line (λ = 365 nm) using a mercury lamp, and KrF excimer laser (λ
= 248 nm), but it is difficult to obtain a resolution of 0.1 μm or less with the extension of the conventional light exposure technology due to the theoretical limit of wavelength.

As a future exposure technique, attention has been paid to the formation of a fine pattern using high brightness X-rays from an SR light source (charged particle storage ring) or the like. Such an X-ray exposure method is roughly classified into a proximity equal-magnification X-ray exposure method using a soft X-ray of 0.5 nm to 2 nm and a soft X-ray of 4 nm to 20 nm.
There is a reduction projection exposure method using a line and a reflective mask. In the former case, the applicant has proposed an exposure apparatus disclosed in Japanese Patent Application Laid-Open No. 2-100131. Since this method has a short exposure wavelength, it is possible in principle to obtain a high resolution of 0.1 μm or less. In the close proximity X-ray exposure method,
A transmissive mask called an equal-magnification X-ray mask is used.
The X-ray permeable portion of the equal-magnification X-ray mask is formed of a light element material such as SiN / SiC called a membrane, and is usually about 2 μm in thickness and made of a thin film of 35 mm square. As a portion that absorbs X-rays in the equal-magnification X-ray mask, a circuit pattern made of a heavy metal such as W, Au, Ta or the like and having a thickness of about 0.5 to 1.0 μm is formed on the membrane as an absorber. ing. Also,
An optical system of the near-magnification X-ray exposure method, for example, magnifies X-rays from a light source into a predetermined field size by an X-ray mirror and
A pattern is transferred through the line mask to the wafer facing the X-ray mask.

On the other hand, the latter X-ray reduction projection exposure method using a reflection type mask with vacuum ultraviolet rays or soft X-rays as an exposure light source uses a reflection type mask different from the above-mentioned equal-magnification X-ray mask.
High resolution image performance can be obtained. Japanese Patent Laid-Open No. 4-2
In the exposure optical system of the X-ray reduction projection exposure method represented by Japanese Laid-Open Patent Publication No. 25215, vacuum ultraviolet rays or soft X-rays are emitted from an undulator light source (SR), and after passing through a reflection mirror optical system, a reflection type mask is used. It is illuminated, and then reaches the wafer through the X-ray reduction projection optical system to form a predetermined pattern. The reflective mask is provided with a multilayer film capable of substantially regular reflection of vacuum ultraviolet rays or soft X-rays. A predetermined pattern is formed on the multilayer film by the X-ray absorber. Since the wavelength of vacuum ultraviolet rays or soft X-rays used for exposure illumination is about 5 nm to 20 nm, the theoretical resolving power derived from the size of the wavelength of exposure light is improved.

However, the above-mentioned proximity equal-magnification X-ray exposure method and X-ray reduction projection exposure method have two problems different from the conventional optical exposure apparatus (such as ultraviolet rays). One is the control of the exposure temperature environment, and the other is the exposure transfer magnification correction mechanism.

In the optical exposure apparatus, since the atmospheric exposure is performed, the former temperature control of the exposure atmosphere has been performed by forced convection of clean air. However, the exposure environment of the X-ray exposure apparatus is a vacuum or a reduced pressure atmosphere such as helium gas, and the same forced convection method cannot be used. Therefore, for example, Japanese Patent Laid-Open No. 2-1
The exposure apparatus shown in 00311 discloses a method of preventing the temperature of a wafer or an X-ray mask from rising by flowing temperature-controlled water controlled to a constant temperature through a wafer chuck.

The latter problem is that in the X-ray exposure apparatus,
It is difficult to make the exposure transfer magnification transferred on the wafer variable by using an X-ray optical system. This is a unique problem that occurs because it is difficult to correct magnification in an optical exposure apparatus that exposes with ultraviolet light using an optical system that uses a lens group in an optical system that uses mirror reflection or an equal-magnification exposure system. Therefore, as a magnification correction method in the X-ray exposure apparatus, a method of applying a minute temperature change to the wafer and utilizing thermal expansion and contraction of the wafer has been considered. This is to change the temperature of the wafer by controlling the temperature of the wafer chuck as shown in Japanese Patent Laid-Open No. 56-112732. As a method of controlling the temperature of the wafer chuck, there is also a method of using water as a heat medium as disclosed in JP-A-57-136325.

FIG. 6 shows a conventional wafer chuck E.
₀ indicates that the temperature of the wafer chuck E ₀ is controlled by flowing a temperature control fluid such as water as a heat medium through the internal pipe 102 of the main body 101 having the adsorption surface 101a. The wafer chuck E ₀ is mounted on an XY stage or the like (not shown) and controls the temperature of the temperature control fluid.
3, since the wafer chuck E ₀ and XY stage choice be mounted when the drive load and the like of the driver is increased, the outer is separated from the wafer stage including the wafer chuck E ₀ and XY stage or the like, for example, the exposure chamber It is generally arranged in the.

The attraction surface 10 of the wafer chuck 101
A suction groove 101b is formed in 1a and the through hole 1
Suction groove 101 by a vacuum pump or the like connected to 01c.
By exhausting b, the wafer W ₀ is moved to the wafer chuck 10
A vacuum suction force that is sucked onto one suction surface 101a is generated.

The wafer W ₀ adsorbed on the adsorption surface 101a of the wafer chuck 101 in this manner is controlled to a predetermined temperature by the temperature control fluid flowing through the internal pipe 102 of the main body 101. That is, since the temperature of the wafer W ₀ gradually rises during the exposure with the high energy X-rays, the temperature of the temperature control fluid is lowered to cool the wafer W ₀ . Further, when it is desired to correct the transfer magnification of the mask pattern transferred to the wafer W ₀ , the temperature of the temperature control fluid is finely adjusted according to the target transfer magnification, and the temperature of the wafer W ₀ during exposure is reduced by a very small amount. Then, the transfer magnification is corrected by utilizing the change and the minute expansion and contraction of the wafer W ₀ .

[0011]

However, according to the above-mentioned conventional technique, as described above, the temperature control unit for controlling the temperature of the temperature control fluid is arranged at a position distant from the wafer stage. The length of the pipe from the adjustment unit to the internal pipe of the wafer chuck is long, and the response of the temperature control is low. Especially, when the transfer magnification is corrected by adjusting the temperature of the wafer, preparation before the start of exposure However, there is an unsolved problem that it takes too much time and the throughput decreases significantly.

Further, in an exposure apparatus using X-rays as exposure light, since the wafer is exposed in a reduced pressure atmosphere such as helium gas or in a high vacuum atmosphere, the effect of cooling the wafer due to forced convection of the atmosphere can be obtained. Unexpectedly, the wafer temperature control uses only heat transfer from the wafer chuck. As a result, a large-capacity and expensive temperature control unit is required, which tends to increase the cost of the exposure apparatus. In addition, since the temperature control unit is installed outside the exposure chamber controlled by a reduced pressure atmosphere such as helium gas, the piping to reach the internal piping of the wafer chuck becomes even longer, and the response of the wafer temperature control is improved. The sex is extremely low.

The present invention has been made in view of the above-mentioned unsolved problems of the prior art. When controlling the temperature of a substrate such as a wafer during exposure, the temperature control response is good, and It is an object of the present invention to provide a substrate holding device and an exposure apparatus that can contribute to miniaturization of a temperature control unit that controls the temperature of a temperature control fluid.

[0014]

In order to achieve the above object, a substrate holding device according to the first invention is a substrate holding plate having a substrate holding surface and a temperature control fluid flow path, and a moving stage for moving the same. And outside the exposure chamber for controlling the temperature control fluid supplied to the temperature control fluid flow path of the substrate holding plate to a predetermined temperature.
A second temperature control means for changing the temperature of the temperature control fluid by a predetermined amount from the predetermined temperature , the first temperature control means being disposed , and the second temperature control means having a substrate holding plate and a moving stage.
Characterized that you have been arranged in the exposure chamber that.

The substrate holding device of the second invention is a substrate holding surface.
And a substrate holder with a temperature control fluid flow path, and
Moving stage and the temperature control fluid flow of the substrate holding plate
First for controlling the temperature control fluid supplied to the moving path to a predetermined temperature
Temperature control means and the temperature of the temperature control fluid to the predetermined temperature.
A second temperature control means for changing the temperature from the temperature by a predetermined amount;
First temperature sensor arranged on the substrate holding surface of the plate holding plate
And a temperature control fluid flow path of the substrate holding board and a second temperature control means
A second temperature sensor disposed between the first temperature sensor and the second temperature sensor;
Control the temperature of the temperature control fluid based on the output of the temperature sensor
It is characterized by having a control means.

[0016]

When the substrate is exposed to high energy such as X-rays, the temperature of the substrate being exposed rises and a transfer deviation occurs due to thermal strain. Therefore, the temperature control fluid flowing in the temperature control fluid flow path of the substrate holding board is controlled to a constant temperature by the first and second temperature control means to prevent the transfer deviation.

When the transfer magnification is corrected by thermal expansion and contraction of the substrate, the temperature of the temperature control fluid is changed by a minute amount by the second temperature control means. By directly mounting or incorporating the second temperature control means on the substrate holding board or the moving stage, the length of the pipe from the second temperature control means to the temperature control fluid flow path of the substrate holding board can be shortened. The responsiveness of substrate temperature control can be greatly improved. As a result, the throughput of the exposure apparatus can be improved.

Further, by controlling the temperature of the temperature control fluid stepwise by using the first and second temperature control means, compared to the case where the temperature control of the substrate is performed only by the first temperature control means. The temperature control unit or the like used for the temperature control means can be significantly downsized. This can greatly contribute to downsizing and cost reduction of the exposure apparatus.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an exposure apparatus according to an embodiment, which comprises a light source 1 as an exposure means for generating X-rays L ₁ such as charged particle storage ring radiation (synchrotron radiation) and X-rays. A magnifying mirror 2 that magnifies the line L ₁ in a predetermined direction (Y-axis direction), an exposure chamber 3 that is controlled by a reduced pressure atmosphere of helium gas, and a wafer stage 4 that is a stage unit disposed therein. It has a mask stage 5, an alignment optical system 6, and a movable shutter 7.

The X-ray L ₁ is expanded in the Y-axis direction by the magnifying mirror 2 as described above, passes through the beam duct 2a controlled to an ultrahigh vacuum, passes through the beryllium window 3a, and is introduced into the exposure chamber 3. The wafer W ₁ which is the substrate on the wafer stage 4 is exposed through the mask held on the mask stage 5. The mask and the wafer W ₁ are in close proximity to each other via a so-called proximity gap, and the pattern of the mask is transferred to the wafer W ₁ by the X-rays transmitted through the mask.
Is transcribed to.

The X-ray magnified by the magnifying mirror 2 is
Since the intensity distribution resembles a Gaussian distribution in the Y-axis direction, uneven exposure such as insufficient exposure occurs at the end of each exposure field angle. Therefore, the exposure time is adjusted by controlling the moving speed of the movable shutter 7 during exposure to prevent the uneven exposure.

Before the exposure is started, the alignment optical system 6 is used to strictly align the wafer W ₁ with the mask to ensure the transfer accuracy of the 1 × exposure.

In such an equal-magnification exposure system (proximity exposure system), magnification correction using a lens group cannot be performed, unlike a reduction projection exposure system. Therefore, as will be described later, the temperature of the wafer W ₁ is finely adjusted, and the thermal expansion or contraction accompanying it is used to change the size of the wafer W ₁ to correct the magnification.

The wafer stage 4 has a wafer chuck 10 which is a substrate holding plate for adsorbing the wafer W ₁ and a moving stage 20 which moves the wafer chuck 10. The moving stage 20 comprises:
A coarse movement stage for stepwise moving each exposure field angle of the wafer W _{1 to} the irradiation region of the X-ray L ₁ , and a stepwise moved exposure field angle by a minute amount based on the output of the alignment optical system 6, A fine movement stage is provided for performing final alignment with respect to a mask or the like.

The wafer chuck 10 has a main body 11 having a suction surface 11a, which is a substrate holding surface, as shown in an enlarged scale in FIG. 2, and the main body 11 has a temperature control for controlling the temperature of the wafer W _1. An internal pipe 12 that is a temperature control fluid flow path for flowing a fluid is formed. Water is generally used as the temperature control fluid flowing through the internal pipe 12. This water is supplied from the water supply pipe 13a to the internal pipe 12 and returned to the temperature control unit 14 which is the first temperature control means through the drain pipe 13b. The first temperature control unit 14 sends the temperature control fluid at a constant temperature as so-called constant temperature water to the water supply pipe 13a.

A temperature adjusting unit 15, which is a second temperature control means, is arranged in the middle of the water supply pipe 13a, and the temperature controller 16 finely adjusts the temperature of the constant temperature water. This is connected to the temperature sensor 17 that detects the temperature of the suction surface 11a of the main body 11 of the wafer chuck 10 and the CPU of the exposure apparatus, and is based on the output of the temperature sensor 17 and the command value transmitted from the CPU or the like. The second temperature control unit 15 is controlled to finely adjust the temperature of the constant temperature water supplied to the wafer chuck 10.

The second temperature control unit 15 is a Peltier element or the like which is capable of highly precise temperature control and has a good responsiveness, and may be built in the main body 11 of the wafer chuck 10 or of the main body 11. It may be fixed to the back side. Alternatively, it may be integrated with the moving stage 20. By arranging a Peltier element or the like having a quick response on the wafer chuck 10 or the moving stage 20 in this way, the temperature of the wafer W ₁ sucked on the suction surface 10a of the wafer chuck 10 can be finely adjusted with high accuracy and speed. be able to.

The attraction surface 11a of the wafer chuck 10 has a
The suction groove 11b is formed, and a vacuum suction force for sucking the wafer W ₁ to the suction surface 11a of the wafer chuck 10 is generated by exhausting the suction groove 11b by a vacuum pump or the like connected to the through hole 11c. .

Incidentally, instead of sucking the wafer by such a vacuum suction force, a known electrostatic suction method may be adopted.

[0031] During the exposure of the X-ray L ₁ is the mask and the wafer W ₁ that absorbs the energy of the X-ray L ₁ is warm. Therefore,
The mask and the wafer W ₁ are cooled by flowing a temperature control fluid (constant temperature water) through the internal pipe 12 of the wafer chuck 10 to prevent transfer deviation due to thermal distortion of these. First temperature control unit 1
The reference numeral 4 serves to absorb the heat of the mask and the wafer W ₁ and recover the temperature-adjusted fluid whose temperature has been raised to cool it to the original temperature and send it to the water supply pipe 13a as constant temperature water. Therefore, since it has a relatively large capacity, it is separated from the wafer stage 10 and disposed outside the exposure chamber 3.

The second temperature adjusting unit 15 is used to finely adjust the temperature of the wafer W ₁ before starting the exposure cycle when it is necessary to correct the transfer magnification. That is, the transfer magnification correction amount is measured in advance before the wafer W ₁ is loaded into the exposure apparatus, the optimum temperature of the wafer W ₁ during exposure is calculated based on the data, and the temperature controller uses this as a command value. Enter in 16. The temperature controller 16 monitors the temperature of the wafer chuck 10 by the temperature sensor 17 and compares it with the optimum temperature, controls the second temperature control unit 15, and controls the temperature immediately before flowing into the internal pipe 12 of the wafer chuck 10. Change the temperature of the conditioning fluid. In this way, the transfer magnification is corrected by thermally expanding or contracting the wafer W ₁ .

The second temperature control unit 15 only slightly heats or cools the temperature control fluid whose temperature has been controlled to be constant temperature water by the first temperature control unit 14 in advance. Tone device is all right. Therefore, a Peltier element or the like having high performance and good responsiveness is built in or directly attached to the wafer chuck. By significantly shortening the time spent correcting the transfer magnification, it can greatly contribute to the improvement of throughput.

A Peltier element or the like may be attached to the moving stage to heat-insulate the pipe connected to the internal pipe of the wafer chuck. In this case, the response is somewhat deteriorated, but there is an advantage that the load on the drive unit that drives the wafer chuck can be reduced.

Even when the transfer magnification correction is not necessary, the temperature of the constant temperature water whose temperature is controlled by the first temperature control unit is gradually changed to the optimum temperature by the second temperature control unit close to the wafer. If adjusted and supplied to the internal pipe of the wafer chuck, the wafer and mask can be cooled efficiently. That is, it is possible to quickly respond to the temperature rise of the wafer and the like due to X-rays, and it is possible to appropriately cool the wafer and the like even if the amount of the temperature control fluid flowing through the internal pipe is small. Therefore, a small and inexpensive unit having a relatively small capacity can be used as the first temperature control unit. This can greatly reduce the size and cost of the exposure apparatus.

Instead of measuring the correction amount of the transfer magnification in advance before loading the wafer on the exposure apparatus,
A method of obtaining the optimum temperature of the wafer by calculating the transfer magnification using the measurement data of the alignment optical system after loading the wafer on the exposure apparatus may be adopted.

Further, the hand for transferring the wafer to the wafer chuck is also provided with the same internal piping, and the temperature control of the temperature control fluid supplied thereto is stepwise controlled by the first and second temperature control units similar to the above. Then, the transfer magnification may be corrected immediately before transferring the wafer to the wafer chuck.

FIG. 3 shows a wafer chuck 30 according to a modification.
This is the one in which a second temperature sensor 37 for detecting the temperature of the temperature control fluid in the water supply pipe 13a is added on the downstream side of the second temperature control unit 15. The second temperature sensor 37 measures the temperature of the temperature control fluid immediately before flowing into the internal pipe 12.
Detected by and introduced into the temperature controller 16,
The output of the temperature sensor 17 is compared. A time constant such as when the temperature of the wafer chuck 30 is raised is measured in advance, and the difference between the target temperature and the current temperature is transiently determined based on a comparison value between this and the output of the first and second temperature sensors 17 and 37. The responsiveness can be improved by controlling the temperature so that the value becomes larger.

By further shortening the time spent for the correction of the transfer magnification, it becomes possible to complete the correction of the transfer magnification during the wafer replacement work. This can further contribute to the improvement of throughput.

Next, an example of a method of manufacturing a semiconductor device using the above-described exposure apparatus will be described. FIG. 4 shows a manufacturing flow of a semiconductor device (semiconductor chip such as IC or LSI, liquid crystal panel, CCD or the like). In step 1 (circuit design), the circuit of the semiconductor device is designed. In step 2 (mask manufacturing), a mask having the designed circuit pattern is manufactured. In step 3 (wafer manufacturing), a wafer is manufactured using a material such as silicon. Step 4 (wafer process) is called a pre-process,
An actual circuit is formed on the wafer by the lithography technique using the mask and the wafer prepared above. Step 5 (assembly) is called a post-process, and is a process of forming a semiconductor chip using the wafer manufactured in Step 4, and an assembly process (dicing, bonding),
It includes steps such as packaging (chip encapsulation). In step 6 (inspection), the semiconductor device manufactured in step 5 undergoes inspections such as an operation confirmation test and a durability test. Through these steps, the semiconductor device is completed,
This is shipped (step 7).

FIG. 5 shows a detailed flow of the wafer process. In step 11 (oxidation), the surface of the wafer is oxidized. In step 12 (CVD), an insulating film is formed on the wafer surface. In step 13 (electrode formation), electrodes are formed on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted in the wafer. Step 15
In (resist processing), a photosensitive agent is applied to the wafer. In step 16 (exposure), the circuit pattern of the mask is printed and exposed on the wafer by the exposure apparatus described above. In step 17 (development), the exposed wafer is developed. In step 18 (etching), parts other than the developed resist image are removed. In step 19 (resist stripping), the resist that is no longer needed after etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer. By using the manufacturing method of this embodiment, it is possible to manufacture a highly integrated semiconductor device, which has been difficult to manufacture in the past.

[0042]

Since the present invention is constructed as described above, it has the following effects.

When the temperature of the substrate such as the wafer during exposure is controlled by the temperature control fluid flowing through the internal pipe of the wafer chuck, the responsiveness of temperature control can be greatly improved. Further, by gradually adjusting the temperature of the temperature control fluid, it is possible to promote the downsizing of the temperature control unit and the like, which can greatly contribute to the downsizing and cost reduction of the entire exposure apparatus.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an exposure apparatus according to an embodiment.

FIG. 2 is an enlarged schematic cross-sectional view showing the wafer stage of FIG. 1 in an enlarged manner.

FIG. 3 is an enlarged schematic sectional view showing a wafer stage according to a modification.

FIG. 4 is a flowchart showing a semiconductor manufacturing process.

FIG. 5 is a flowchart showing a wafer process.

FIG. 6 is a schematic sectional view showing a wafer stage according to a conventional example.

[Explanation of symbols]

1 light source 2 magnifying mirror 3 exposure room 4 Wafer stage 10,30 Wafer chuck 12 Internal piping 14,15 Temperature control unit 16 Temperature controller 17,37 Temperature sensor 20 moving stages

Continuation of front page (51) Int.Cl. ⁷ identification code FI H01L 21/30 502H (56) Reference JP-A-5-335200 (JP, A) JP-A-5-21308 (JP, A) JP-A-5-21308 (JP, A) 4-318851 (JP, A) JP 3-62920 (JP, A) JP 2-94514 (JP, A) JP 1-117323 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/027 G03F 7/20 H01L 21/68

Claims (4)

(57) [Claims] 1. A substrate holding plate having a substrate holding surface and a temperature control fluid flow path, a moving stage for moving the substrate holding plate, and a predetermined temperature control fluid supplied to the temperature control fluid flow path of the substrate holding plate. The first is placed outside the exposure chamber to control the temperature
Has a temperature control means, the second temperature control means moves the stay and the substrate holding plate to vary by a predetermined amount the temperature of the temperature control fluid from the predetermined temperature
Is disposed in an exposure chamber having
That substrate holding apparatus. 2. The second temperature control means is configured to correct the transfer magnification of the substrate by changing the temperature of the substrate held on the substrate holding surface. The substrate holding device described. 3. A substrate having a substrate holding surface and a temperature control fluid flow path.
A plate holding plate, a moving stage for moving the plate holding plate, and temperature control supplied to the temperature control fluid flow path of the substrate holding plate.
First temperature control means for controlling the fluid to a predetermined temperature, and changing the temperature of the temperature control fluid from the predetermined temperature by a predetermined amount.
Second temperature control means for activating the first temperature sensor and a first temperature sensor arranged on the substrate holding surface of the substrate holding plate.
And between the temperature control fluid flow path of the substrate holding board and the second temperature control means.
A second temperature sensor disposed in the first temperature sensor and a temperature control fluid based on the outputs of the first and second temperature sensors.
Group having control means for controlling the temperature of
Plate holding device. 4. exposure having a substrate holding apparatus of claims 1 to 3 any one of claims, the exposure means for exposing a substrate held thereto device.