JP3101332B2 - X-ray 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 an X-ray exposure apparatus for performing exposure using X-rays, and more particularly, to an X-ray exposure apparatus in which an X-ray attenuating atmosphere is provided between a chamber and a mask holder holding an X-ray mask. The present invention relates to an X-ray exposure apparatus that achieves sealing properties and facilitates gas replacement in a chamber.

[0002]

2. Description of the Related Art Conventionally, in an LSI manufacturing process, a light exposure apparatus represented by a reduction projection exposure apparatus is generally used. However, as the LSI pattern becomes higher in density and higher in integration, the circuit pattern becomes finer, and the formation of such a finer circuit pattern by a light exposure apparatus is approaching its limit. Therefore, recently, an X-ray exposure apparatus capable of forming a finer circuit pattern than a light exposure apparatus has been developed. This X-ray exposure apparatus uses a helium gas or the like having a pressure substantially equal to the atmospheric pressure between the X-ray extraction window through which the X-ray passes and the X-ray mask in order to minimize attenuation of the X-ray in the atmosphere. An airtight chamber structure in which a gas atmosphere (X-ray low attenuation atmosphere) is provided is generally employed.

FIG. 4 is a schematic diagram showing a conventional general X-ray exposure apparatus using a synchrotron as an X-ray source.

That is, an X-ray 1 radiated from a synchrotron (X-ray source) not shown is reflected by an X-ray reflecting mirror (not shown) and passes through a bellows 2 from a high vacuum port (not shown). The X-ray is passed through the X-ray extraction window 3 into the chamber 4 in a helium gas atmosphere, and is irradiated on the X-ray mask 5. The X-ray mask 5 is detachably held in the chamber 4 via a mask holder 6, and is irradiated with X-rays through the X-ray mask 5 to the surface of a semiconductor wafer 7 as a sample, thereby forming a wafer table 8. The drawing pattern 5a of the X-ray mask 5 is transferred onto the semiconductor wafer 7 which is detachably held in the semiconductor wafer 7.

Here, the X-ray emitted from the X-ray extraction window 3 is
The attenuation in the atmosphere is large, and to prevent this attenuation,
The optical path from the X-ray extraction window 3 to the X-ray mask 5 needs to be an X-ray low attenuation atmosphere such as a helium atmosphere.

An alignment optical system 9 for positioning the X-ray mask 5 and the semiconductor wafer 7 is disposed on the back side of the mask holder 6 in the chamber 4.

[0007]

However, in the above-mentioned conventional example, the mask holder 6 for mounting the X-ray mask 5 is used.
Cannot be moved because the X-ray mask 5 is directly attached to the chamber 4. Therefore, the alignment between the alignment optical system 9 and the X-ray mask 5 is performed by the X-ray mask 5.
Is performed by using an alignment mark (not shown) drawn in (1) to obtain an optical displacement amount, and moving the alignment optical system 9 in accordance with the displacement amount.

The reproducibility of the position of the X-ray mask 5 is only due to the reproducibility of a mask transport system (not shown).
Each time the mask is replaced, the displacement of the X-ray mask 5 with respect to the X-ray 1 does not match the displacement of the X-ray mask 5 with respect to the semiconductor wafer 7. Moreover, since the angle on the X-ray mask 5 side cannot be matched with the traveling direction of the wafer table 8, unless the angle on the semiconductor wafer 7 side is matched with the angle on the X-ray mask 5 every time one chip is transferred, the X-ray Since the gap between the mask 5 and the semiconductor wafer 7 is extremely small, there is a risk of contact.

For this reason, not only does the alignment accuracy between the X-ray mask 5 and the semiconductor wafer 7 and the X-rays 1 drop, but it takes a considerable time for alignment and transfer, leading to a reduction in LSI productivity. There was a problem.

When the interior of the chamber 4 is replaced with a gas atmosphere such as helium gas (X-ray low attenuation atmosphere) in the above conventional example, the X-ray mask 5 is moved from the mask holder 6 as shown in FIG. In the detached state, the replacement gas 11 is injected from the gas injection port 10 and blown out of the chamber 4 to expel the atmosphere from the chamber 4. In this state, the X-ray mask 5 is held by the mask holder 6. I was However, in this case, there is a problem that the purity of the replacement gas 11 becomes low and the attenuation of the X-rays 1 becomes large.

Therefore, as shown in FIG. 6, in order to seal the mask holder 6, the entire mask holder 6 is
2, the X-ray mask 5 is held in a mask holder 6 while blowing the replacement gas 11 in the same manner as described above. In this case, the number of operations for moving the chamber 4 to take up a space for mounting the lid 12 and returning the chamber 4 to a fixed position increases, and the position of the chamber 4 with respect to the X-rays 1 varies, and the chamber 4 If the pressure inside is reduced, the vacuum chuck cannot be used.
There is a problem that it is necessary to remove the X-ray mask 5 from the device.

In view of the above, the present invention has been made to improve the alignment accuracy between an X-ray mask and a semiconductor wafer and an X-ray, to improve the productivity of an LSI, and to facilitate gas replacement in a chamber. The purpose is to provide.

[0013]

To achieve the above object, an X-ray exposure apparatus according to the present invention provides an X-ray exposure apparatus for generating X-rays.
An X-ray extraction window for extracting X-rays emitted from a radiation source, and a chamber for setting an X-ray low attenuation atmosphere until the X-ray mask surface is irradiated with the X-rays emitted from the X-ray extraction window. Then, the drawing pattern of the X-ray mask is irradiated on the sample surface to expose the drawing pattern of the X-ray mask to the sample surface.
In the X-ray exposure apparatus, a mask holder for detachably holding the X-ray mask is mounted on a mask table formed separately from the chamber, and these are hermetically sealed between the mask holder and the chamber. A lid that interposes an elastic body configured to allow movement of the mask table with respect to the chamber, and further keeps the chamber airtight by bringing a leg into contact with a front surface on the sample surface side of the chamber. And a lid configured to cover the mask holder and the elastic body with the X-ray mask removed.

[0014]

A replacement means for replacing the inside of the chamber with the X-ray low-attenuation gas with the lid attached;
When the lid is opened and the X-ray mask is mounted on the mask holder, the apparatus further includes gas pressure control means for increasing the pressure of the X-ray low-attenuation gas to prevent mixing with the atmosphere. You can also.

[0016]

According to the first aspect of the present invention, the X-ray mask is aligned with the alignment optical system by arbitrarily moving the mask holder via the mask table. The angle of the X-ray mask can be aligned with the traveling direction of the wafer table, thereby improving alignment accuracy and LSI production efficiency.

In particular, according to the first aspect of the present invention, since the chamber is kept airtight while covering the mask holder and the elastic body via the lid, the X-ray mask is removed from the mask holder. Even when performing gas replacement by reducing the pressure in the chamber in this state, the pressure on the front and back of the elastic body is almost the same, and it is possible to prevent the elastic body from being damaged or deformed due to the pressure difference between the front and back of the elastic body. it can.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. The same members as those in the above-described conventional example are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 1 shows a first embodiment, in which a mask table 13 movable in X, Y, .theta., Z and tilt directions is arranged inside a chamber 4 separately.
X is connected to one end of the mask table 13 through the bellows 2.
A mask holder 6 for detachably holding the X-ray mask 5 is connected to the other end of the line extraction window 3.

Between the mask table 6 and the chamber 4, a ring-shaped bent portion 14 having a U-shaped cross section at the periphery is provided.
a, an elastic body 14 that can expand and contract along a plane is disposed. The elastic body 14 hermetically seals the space between the mask table 6 and the chamber 4, and the presence of the elastic body 14 The relative movement of the mask table 6 with respect to the chamber 4 is not hindered.

Thus, for example, the alignment optical system 9
The alignment between the mask and the X-ray mask 5 is performed by obtaining an optical displacement amount using an alignment mark (not shown) drawn on the X-ray mask 5, and via the mask table 13 according to the displacement amount. By moving the X-ray mask 5 in the traveling direction of the wafer table 8, the angle can be adjusted with respect to the semiconductor wafer 7 in the same manner. As a result, it is possible to improve the alignment accuracy and the production efficiency of the LSI.

The elastic member 14 may have any shape as long as the elastic member 14 does not hinder the relative movement of the mask table 6 with respect to the chamber 4.

FIG. 2 shows a second embodiment. When the inside of the chamber 4 is decompressed in order to replace the inside of the chamber 4 with a gas atmosphere, the whole elastic body (seal) 14 is airtightly covered.
A lid 12 is provided to prevent this from being damaged or deformed. The lid 12 is provided on the ceiling of the chamber 4 via a connecting rod 15 for attachment and detachment. It is connected to the moving mechanism 16.

The lid moving mechanism 16 includes a rotating mechanism for inserting and retracting the lid 12 between the X-ray mask 5 and the semiconductor wafer 7, and a linear moving mechanism for setting the lid 12 at the sealing position. Thus, the lid 12 can be moved back and forth and rotated via the lid moving mechanism 16.

When the lid 12 is inserted and retracted between the X-ray mask 5 and the semiconductor wafer 7, the chamber 4 is moved to prevent the obstacles from interfering with each other. A chamber moving mechanism 17 that changes the distance between the semiconductor wafer 5 and the semiconductor wafer 7 is provided. That is, the chamber moving mechanism 17 includes a surface plate 18 and a movable body 19 that can travel on the surface plate 18, and the chamber 4 is mounted on the upper surface of the movable body 19. Note that the displacement caused by the movement of the chamber 4 at this time is absorbed by the bellows 2, and this kind of moving mechanism can be provided on the wafer table 8 side so that it can be moved.

The gas replacement in the chamber 4 is performed as follows.

That is, first, the space between the X-ray mask 5 and the semiconductor wafer 7 is secured by retracting the chamber 4 via the chamber moving mechanism 17. Then, while removing the X-ray mask 5 from the mask holder 6, the lid 1
2 is rotated and inserted between the X-ray mask 5 and the semiconductor wafer 7, and further retracted to set the leg portion 12 a at a sealing position where the leg portion 12 a contacts the surface of the chamber 4. In this state, the inside of the chamber 4 is decompressed and then replaced with a gas atmosphere, and the lid 12 is advanced and then rotated to retract from the space between the X-ray mask 5 and the semiconductor wafer 7. And
When the X-ray mask 5 is mounted on the mask holder 6, the gas pressure inside the chamber 4 is set slightly higher than the atmospheric pressure so as not to damage the X-ray mask 5, and as shown in FIG. This is performed in a state in which the chamber 4 is in a closed state, whereby it is possible to prevent the air from entering the chamber 4.

Thus, the lid 12 provided in the chamber 4
The whole of the X-ray mask 5 is hermetically covered via a gas barrier, and the gas is replaced in this state to keep the gas purity in the chamber 4 constant and minimize the attenuation of the X-rays 1. The movement of the chamber 4 when the entire X-ray mask 5 is covered by 12 can be easily and always positioned at a fixed position, and the position reproducibility can be improved.

FIG. 3 shows a modification of the second embodiment, in which the gas in the chamber 4 can be replaced without removing the X-ray mask 5 from the mask holder 6. . That is, in the second embodiment, since the pressure is reduced during the gas replacement, the mask holder 6 using the vacuum chuck cannot be used. Therefore, it is necessary to remove the X-ray mask 5 from the mask holder 6.

Therefore, this modification uses a mask holder 6 that can be used even in a vacuum, such as an electrostatic chuck or a mechanical chuck, and balances the pressure on the front and back of the X-ray mask 5. A bypass passage 20 for communicating the inside of the lid 12 with the inside of the chamber 4 is provided to prevent the X-ray mask 5 from being damaged or damaged by the pressure difference between the front and back surfaces. The bypass passage 20 is provided with a valve 21 for switching between penetration and sealing inside the bypass passage 20.

As a result, it is not necessary to remove the X-ray mask 5 at the time of maintenance, so that the risk of damaging the X-ray mask 5 can be reduced.

[0032]

Since the present invention has the above configuration,
According to the first aspect of the present invention, the X-ray mask can be moved via the mask table, whereby the alignment accuracy can be improved and the LSI production efficiency can be improved. In addition, the sealing property between the mask holder 6 and the chamber 4 can be ensured via the elastic body, and the movement of the mask table can be prevented from being hindered by the presence of the elastic body.

In particular, according to the first aspect of the present invention, since the chamber is kept airtight while covering the mask holder and the elastic body via the lid, the X-ray mask is removed from the mask holder. Even when performing gas replacement by reducing the pressure in the chamber in this state, the pressure on the front and back of the elastic body is almost the same, and it is possible to prevent the elastic body from being damaged or deformed due to the pressure difference between the front and back of the elastic body. it can.

[0034]

[Brief description of the drawings]

FIG. 1 is a schematic plan sectional view showing a first embodiment of the present invention.

FIG. 2 is a schematic side sectional view showing a second embodiment of the present invention.

FIG. 3 is a schematic side sectional view showing a modification of the second embodiment of the present invention.

FIG. 4 is a schematic plan sectional view showing a conventional example.

FIG. 5 is a schematic plan sectional view showing a state of gas replacement in a conventional example.

FIG. 6 is a schematic plan sectional view showing another state of gas replacement in a conventional example.

[Explanation of symbols]

 Reference Signs List 3 X-ray extraction window 4 Chamber 5 X-ray mask 6 Mask holder 7 Semiconductor wafer (sample) 8 Wafer table 9 Alignment optical system 12 Lid 13 Mask table 14 Elastic body (Seal) 16 Lid moving mechanism 17 Chamber moving mechanism 20 Bypass aisle

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Takahiro Murata 1 Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture Toshiba Research Institute Co., Ltd. (56) References JP-A-58-73116 (JP, A) JP-A-62-94928 (JP, A) JP-A-63-307731 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/027 G03F 7/20 503 G03F 7/20 521

Claims (2)

(57) [Claims] 1. X-rays emitted from an X-ray source for generating X-rays
An X-ray extraction window for extracting X-rays, and a chamber in which the X-ray mask surface is irradiated with X-rays emitted from the X-ray extraction window until the X-ray mask surface is irradiated with a low-attenuation atmosphere; An X-ray exposure apparatus that exposes a drawing pattern of an X-ray mask on the sample surface by irradiating the sample surface with the pattern,
A mask holder for detachably holding the X-ray mask is attached to a mask table formed separately from the chamber, and the mask holder and the chamber are hermetically sealed and the mask table for the chamber is provided. A lid configured to interpose an elastic body configured to allow the movement of the X-ray, and further holding the chamber airtight by bringing a leg into contact with the front surface of the chamber on the sample surface side; An X-ray exposure apparatus, comprising: a lid configured to cover the mask holder and the elastic body with the mask removed. 2. A replacement means for replacing the inside of the chamber with an X-ray low-attenuation gas with the lid mounted, and when the lid is opened and the X-ray mask is mounted on the mask holder. 2. The X-ray exposure apparatus according to claim 1, further comprising gas pressure control means for increasing the pressure of said X-ray low-attenuation gas to prevent air from entering.