JPH02301126A - X-ray exposure device - Google Patents

Abstract

PURPOSE:To accurately superpose a mask with a wafer by connecting an alignment optical system to an X-ray source via a high rigidity vibration shielding member instead of securing the system to an anti-vibration base, and connecting the mask to a wafer aligning unit via a low rigidity vibration shielding member. CONSTITUTION:An X-ray generated from a focus 17 of an X-ray source 3 is externally output via a beryllium window 18, and a pattern on a mask 10 is transferred to a wafer 13. In this case, the positional deviation of the mask 10 from the wafer 13 is always detected by an alignment optical system 9, and a mask holder 12 or a wafer holder 14 is so controlled as not to generate the deviation. A surface plate 15 secured with a wafer stage 14 for the holder 12 is supported by an air spring 16, the deviation of the spring 16 is absorbed by a vibration shielding member 11 for coupling the system 9 to the holder 12, and even if the plate 15 is inclined, the system 9 is not inclined, and the positional relationship of the focus 17 of the source 3 is not varied. Vibration generated from a rotary target 19 of the source 3 is so shielded by a vibration shielding member 8 as not to transmit to the system 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an X-ray exposure apparatus that is applicable to manufacturing semiconductor integrated circuits having turns.

[Conventional technology]

As a conventional technique, for example, Japanese Patent Publication No. 53-34466
As shown in the above publication, there is an X-ray exposure apparatus using an electron beam excitation type X-ray source.

A conventional X-ray exposure apparatus includes an X-ray source, a mask-wafer alignment device, and a vibration isolator equipped with the mask-wafer alignment device.

Next, a conventional X-ray exposure apparatus will be described in detail with reference to the drawings.

FIG. 2 is a side view showing an example of a conventional X-ray exposure apparatus.

The X-ray exposure apparatus shown in FIG.
The X-ray source 3 fixed to the pedestal 2, the mask holder 12 that holds the mask 1O, the wafer stage 14 that holds the wafer 13 and positions the wafer 13, and the positional shift between the mask 10 and the wafer 13 are It includes an alignment optical system 9 for detection, a surface plate 15 to which the mask holder 12, the wafer stage 14, and the alignment optical system 9 are fixed, and an air spring 16 that supports the surface plate 15. .

Here, the X-ray source 13 is an X-ray focal point 1 on a rotating target 19.
The mask 10 is irradiated with X-rays from t to transfer the mask pattern onto the wafer 13.

Mask holder 12. The wafer stage 14 and the alignment optical system 9 are supported by a surface plate 15 and an air spring 16, and are designed to prevent vibrations from the floor 1 from being transmitted and to suppress vibrations generated by movement of the wafer stage 14, etc. ing.

Further, the X-ray source 3 and the alignment optical system 9 are connected by a flexible member 21 so that vibrations generated from the rotating target 19 of the X-ray source 3 are not transmitted to the alignment optical system 9.

The air spring 16 is equipped with a valve 22, detects the height of the surface plate 15, and is controlled so that the height of the surface plate 15 is kept constant.

However, due to the dead zone of the sensor that detects the height of the surface plate 15, a positioning error of about 1rffrfI occurs in the height direction.

When the surface plate 15 tilts due to a positioning error of the air spring 16,
Mask holder 12 on surface plate 15. wafer stage 14,
The alignment optical system 9 is also tilted, and the focus 17 of the X-ray source 3 is shifted from the alignment optical axis, resulting in a problem that the mask pattern is transferred onto the wafer 13 with a shift.

For example, A1 is the distance between the focal point 17 of the X-ray source 3 and the mask 10, B is the gap between the mask 10 and the wafer 13, and C5 is the height of the air spring 16 and the distance between the focal point of the X-ray source.
It is assumed that the positioning error in the height direction is D, the support interval of the air springs 16 is E, and the dimensions of each part are as follows.

A = 500 mm B = 0.04 mm C = 1000 mm D '' 1 mm E = 1000 mm At this time, the transfer deviation F of the mask pattern is A
becomes le.

In fine pattern transfer with a minimum line width of about 0.5 μm,
Transfer deviation F must be suppressed to 0.01 μm or less, and 0.
．． A transfer deviation of 0.8 μm is not within an acceptable range.

Furthermore, in recent years, X-ray exposure apparatuses that use synchrotron radiation (SR light) with higher brightness and higher directionality as a light source have attracted attention, but similar problems arise in this case as well.

In the case of an X-ray exposure device that uses SR light as a light source, the distance A between the X-ray source and the mask, the height of the air spring, and the distance C between the X-ray source are large and can be considered as A-C, so the other conditions are set as above assumptions. If this is true, the transfer deviation F will be as follows.

The minimum line width for X-ray exposure equipment using SR light as the light source is 0.25.
Since the purpose is to transfer a pattern with a higher resolution of .mu.m or less, a transfer deviation of 0.04 .mu.m becomes a big problem.

[Problem to be solved by the invention]

In the conventional X-ray exposure apparatus described above, the alignment optical system is fixed on a surface plate supported by an air spring, so if a positioning error occurs in the air spring, the focus of the X-ray source shifts from the alignment optical axis. Therefore, there is a drawback that transfer displacement of the mask pattern occurs.

[Means to solve the problem]

The X-ray exposure apparatus of the present invention includes an X-ray source that generates X-rays, an alignment optical system that detects a positional shift between a mask and a wafer, which are connected to the X-ray source through a highly rigid vibration isolation member, and a rigid vibration isolation member. The apparatus includes a mask and wafer alignment device connected to the alignment optical system by a low vibration isolation member, and a vibration isolation table on which the mask and wafer alignment device is mounted.

〔Example〕

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a side view showing an embodiment of the present invention.

The X-ray exposure apparatus shown in FIG.
, an X-ray source 3 fixed to a pedestal 2, an alignment optical system 9 connected to the X-ray source 3 by a vibration isolation member 8 made of highly rigid hard rubber, etc., which holds the mask 10 and is made of a rigid material. A mask holder 12 connected to the 7-line optical system 9 by a vibration isolation member 11 made of a low and flexible material, a wafer stage 14 for positioning the wafer 13 by placing it facing the yask 10, and the mask holder 12 and the wafer. It is configured to include a surface plate 15 on which a stage 14 is mounted, and an air spring 16 that supports the surface plate 15.

The X-rays generated from the focal point 17 of the X-ray source 3 pass through the beryllium window 1.
The pattern on the mask 10 is transferred to the wafer 13. At this time, the alignment optical system 9 constantly detects the misalignment between the mask IO and the wafer 13, and controls the mask holder 12 or the wafer stage 14 so that no misalignment occurs.

The surface plate 15 to which the wafer stage 14 carrying the mask holder 12 is fixed is supported by an air spring 16, which prevents vibrations from being transmitted from the floor l and also prevents the step-and-repeat operation of the wafer stage 14. It is designed to suppress the accompanying vibrations.

The positional deviation of the air spring 16 at this time is absorbed by the vibration isolation member 11 that connects the alignment optical system 9 and the mask holder 12, so that even if the surface plate 15 is tilted, the alignment optical system 9 will not be tilted. The positional relationship between the focal point 17 and the X-ray source 3 does not change.

Therefore, even if the surface plate 16 is tilted due to a positioning error of the air spring 16, the positional deviation between the mask 10 and the wafer 13 relative to the focal point 17 of the X-ray source 3 can be accurately detected, and transfer deviation will not occur.

Vibrations generated from the X-ray source 30 rotating target 19 are blocked by the vibration isolation member 8 so as not to be transmitted to the alignment optical system 9.

Since the vibration generated from the rotating target 19 has a high frequency and a small amplitude, it can be blocked by a vibration isolation member made of hard rubber or the like that is more rigid than the vibration isolation member.

Therefore, the positional relationship between the X-ray source 3 and the seven-line optical system 9 does not shift.

In this embodiment, an X-ray exposure apparatus using an electron beam excitation type X-ray source has been described, but similar effects can be expected in an X-ray exposure apparatus using SR light. In this case, the X-ray source does not have a rotating target that generates vibrations, but a highly rigid vibration isolating member blocks the vibrations generated by the vacuum pump that maintains the beam line through which the X-rays pass in an ultra-high vacuum. be able to.

In addition, in this embodiment, the alignment optical system 9 is connected to the airtight chamber 2.
0, the X-ray source 3 and the mask holder 12
Airtightness is maintained by being connected to the vibration isolation members 8 and 9 via the vibration isolation members 8 and 9. Therefore, the airtight chamber 20 can be filled with helium gas that has low X-ray attenuation, and X-ray attenuation due to the atmosphere can be prevented.

〔Effect of the invention〕

In the X-ray exposure apparatus of the present invention, instead of fixing the alignment optical system to a vibration isolation table, the X-ray source is connected to the vibration isolation member with high rigidity, and the alignment optical system of the mask and the wafer is connected to the vibration isolation member with low rigidity. By connecting them by , the position of the 7-line optical system will not shift due to the position shift of the vibration isolation table, so there is an effect that the mask and wafer can be superimposed with high accuracy.

Furthermore, since an inexpensive vibration isolating table without a servo mechanism can be used, there is an effect that the device is inexpensive.

[Brief explanation of drawings]

FIG. 1 is a side view showing an embodiment of the present invention, and FIG. 2 is a side view showing a conventional example. 1... Floor, 2... Frame, 3...
・X-ray source, 8゜11... Vibration isolation member, 9...
...Alignment optical system, lO...Mask, 12...Masked holder, 13...Wafer, 14...Wafer stage, 15...Masked Board, 16...Air spring.

Claims (1)

[Claims] An X-ray source that generates X-rays, an alignment optical system that detects a positional shift between a mask and a wafer, which are connected to the X-ray source through a vibration isolation member with high rigidity, and an alignment optical system that uses a vibration isolation member with low rigidity. An X-ray exposure apparatus comprising: a mask and wafer alignment device connected to the mask and wafer alignment device; and a vibration isolation table on which the mask and wafer alignment device is mounted.