JPH05283319A - X-ray lithography equipment - Google Patents

Abstract

PURPOSE:To provide a title equipment improved in exposure precision by controlling the swing speed of a Be window and that of toroidal X-ray mirror at the same time to correct exposure ununiformity. CONSTITUTION:An SOR ring 1 as a high-intensity SOR (synchrotron radiation X rays) light generating source is provided as well as an ultrahigh vacuum beam line 2 which extracts SOR light from this SOR ring, and toroidal X-ray mirror 3 is installed which condenses and reflects SOR light in this beam line and swings to enlarge exposure light area. A Be (beryllium) window 4 which swings in synchronization with the swing of the toroidal X-ray mirror, extracts X rays, and exposes a masked wafer to light is arranged at the terminal of a beam line, and a control circuit 7 is provided which the swing speed of this Be window and that of this toroidal X-ray mirror are multiplied by the reciprocal of an estimated rate of changes in SOR light intensity and at the same time corrects exposure ununiformity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray lithographic apparatus for pattern transfer using SOR (synchrotron radiation X-ray) light.

[0002]

2. Description of the Related Art SOR (synchrotron radiation X-ray) light is an electron (generally charged particles) having a speed close to high speed.
Is an electromagnetic wave emitted when performing a motion such as a circular orbit subject to acceleration.

Such SOR light was first observed in a synchrotron for nuclear experiments. After that, an electron storage ring capable of orbiting electrons stably for several hours was created and used as a light source in the extreme ultraviolet and soft X-ray regions for physical property experiments. And, recently, it has come to be noticed as a radiation source of an X-ray lithographic apparatus.

In this type of exposure apparatus, the SOR light extracted from the SOR ring as a high intensity SOR light source must be condensed by a mirror and reflected to expose the masked wafer.

The above-mentioned mirror is a plane mirror and X is a plane mirror.
It may be a toroidal X-ray mirror that curves in the -Y direction. In the above flat mirror, the reflected SOR light is expanded, so that the reflection shape is not distorted, but the intensity is limited. In the toroidal X-ray mirror, S
While there is an effect of increasing the intensity by collecting the OR light, SOR
It is known that the light shape is curved.

Furthermore, when the distance from the SOR ring to the mask wafer is 10 m, the extracted SOR light becomes remarkably gentle. In this case, SOR
Since the light only has a slit shape of about 5 mm in the vertical direction, in order to expose a large area, the mirror or the mask and the wafer are rocked together, or the beam is moved by using the rocking of the electron orbit. I have to shake it.

[0007] Normally, the mirror side is generally driven to swing because it is mechanically simple. However,
The use of the plane mirror does not have the effect of increasing the intensity by condensing the SOR light unlike the toroidal X-ray mirror, so that the throughput becomes low and it is not suitable for a high-density exposure apparatus.

For these reasons, it is common sense to use a toroidal X-ray mirror to collect and reflect SOR light to obtain the effect of increasing the intensity and the effect of improving the throughput. However, as described above, in the case of this toroidal X-ray mirror, it is avoided that the SOR light shape is curved and that when the mirror is swung, the curved shape is sequentially changed due to the change of the incident angle. I can't.

[0009]

When the SOR light extracted from the SOR ring to the beam line is condensed and reflected by the toroidal X-ray mirror, the SOR light shape becomes a curved slit shape. Further, when the exposure is performed by swinging the mirror at a uniform speed in order to increase the exposure area, there is a difference in the degree of focusing of the SOR light due to the sequential changes in the curved slit shape, which causes an in-plane exposure. However, there is a problem that the SOR light intensity becomes uneven and the exposure unevenness phenomenon occurs.

The present invention has been made under such circumstances, and an object of the present invention is to collect and reflect SOR light extracted from a SOR ring to a beam line by a toroidal X-ray mirror and to expose an exposed area. An object of the present invention is to provide an X-ray lithographic apparatus that improves exposure accuracy by correcting exposure unevenness caused by a change in the shape of curved SOR light when it is swung for enlargement.

[0011]

To achieve the above object, the first invention is a high intensity SOR (synchrotron radiation X).
Line) is equipped with an SOR ring as a light source.
An ultra-high vacuum beam line for extracting the SOR light from the ring is provided, and a toroidal X-ray mirror that collects and reflects the SOR light and swings to expand the exposure area is installed in the beam line. And a Be (beryllium) window for oscillating in synchronization with the oscillation of the toroidal X-ray mirror to extract the X-rays and expose the masked wafer.
An X-ray lithography comprising a control means for multiplying the swing speed of the Be window and the toroidal X-ray mirror by the reciprocal of the estimated SOR light intensity change rate to simultaneously control the speed to correct the exposure unevenness. It is a device.

A second invention comprises an SOR ring as a high intensity SOR (synchrotron radiation X-ray) light source, and an ultrahigh vacuum beamline for extracting SOR light from the SOR ring. A Be (beryllium) window in which a toroidal X-ray mirror that collects and reflects SOR light and swings to expand the exposure area is installed, and an X-ray is extracted at the end of the beam line to expose a masked wafer. And a control means for correcting the exposure unevenness by controlling the swing speed of the toroidal X-ray mirror by multiplying it by the reciprocal of the estimated SOR light intensity change rate. is there.

[0013]

In the first aspect of the present invention, when the toroidal X-ray mirror and the Be window are simultaneously swung to collect and reflect the toroidal X-ray mirror and to expand the exposure area, the Be window and the toroidal X-ray mirror are swung. The velocity is simultaneously controlled by multiplying the dynamic velocity by the reciprocal of the estimated SOR light intensity change rate.

In the second invention, when the toroidal X-ray mirror is swung to collect and reflect the toroidal X-ray mirror and to increase the exposure area, this swing speed is estimated.
The speed is controlled by multiplying the inverse of the OR light intensity change rate. In any of the inventions, it is possible to correct the exposure unevenness due to the change of the SOR light shape.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 1, an X-ray lithographic apparatus is constructed.

That is, reference numeral 1 in the drawing is an SOR ring,
It is a light source of high intensity SOR (synchrotron radiation X-ray) light. This is because electrons entering from an accelerator (not shown) are circulated in a vacuum pipe while bending a trajectory by a deflection electromagnet, and are accelerated and maintained at a predetermined energy by an accelerator provided therein in synchronization with one cycle of electrons.

Further, through a quadrupole electromagnet for converging the electron beam, SOR light is extracted along the beam line 2 in a tangential direction from a portion where the electron trajectory is bent by the deflection electromagnet.

The SOR light extracted to the beam line 2 has a spread of about 1 mrad in the direction perpendicular to the orbital plane, and in the orbital plane, it is curved at a corner just like a car headlight sweeping a curve sweeps. Spread in a fan-shaped area with equal apex angles. The spread of the actually used light in the orbital plane is determined by the inner diameter of the beam duct for extracting the emitted light or the slit width in the beam duct.

The beam line 2 is formed in an ultrahigh vacuum for extracting SOR light from the SOR ring 1, and a toroidal X-ray mirror 3 is arranged in the middle thereof. The mirror 3 collects and reflects the SOR light guided through the beam line 2. Further, it is mechanically connected to a swing drive source (not shown) and swings to increase the exposure area.

A Be (beryllium) window 4 is arranged on the SOR light reflecting side of the toroidal X-ray mirror 3 and at the end of the beam line 2. This is for transmitting the X-rays of the SOR light guided to the beam line 2 formed in the ultrahigh vacuum. Here, the toroidal X-ray mirror 3 is mechanically connected to a drive source (not shown) so as to swing in synchronization with the swing of the toroidal X-ray mirror 3. On the X-ray extraction side of the Be window 4,
A mask 5 having a predetermined pattern and a wafer 6 coated with a resist are arranged.

The oscillating drive source of the toroidal X-ray mirror 3 and the oscillating drive source of the Be window 4 are electrically connected to a control circuit 7 as a control means. This control circuit 7
The speed of each swing drive source is controlled at the same time.

That is, simply, the Be window 4 for extracting X-rays is used.
Rocks in synchronization with the toroidal X-ray mirror 3 to cause SOR
When the light is extracted, unevenness in exposure occurs in the vertical direction due to the loss of the portion extracted from the Be window 4 and the difference in the degree of focusing.

S protruding from the Be window 4 that causes this
Since the loss of the OR light and the change in the degree of converging can be obtained by ray tracing calculation, the rate of change in the SOR light intensity that occurs in the vertical direction when rocking at a uniform speed can be estimated. The control circuit 7 multiplies the rocking speeds of the toroidal X-ray mirror 3 and the Be window 4 by the reciprocal of the estimated rate of change of the SOR light intensity, and simultaneously controls the speeds.

Thus, high intensity SOR light is generated in the SOR ring 1, and the SOR light is extracted from the SOR ring 1 to the beam line 2 of ultrahigh vacuum. The SOR light extracted to the beam line 2 is condensed and reflected by the toroidal X-ray mirror 3 installed on the way.

Since the SOR light reflected here has only a small width in the vertical direction, it is oscillated to expand the exposure area. The SOR light oscillates, passes through the Be window 4 arranged at the end of the beam line 2, and reaches the mask 5 and the wafer 6.

The Be window 4 is a toroidal X-ray mirror 3
The wafer 6 is exposed to light through the pattern formed on the mask 5 by the transmitted X-rays.

Here, as shown in FIG. 2, the Be window 4 has a rectangular shape and corresponds to the shape of the slit-shaped SOR light 8 which is condensed and reflected by the toroidal X-ray mirror 3 and curved. That is, it is a rectangular area that does not hinder the transmission of the SOR light 8.

B is synchronized with the toroidal X-ray mirror 3 described above.
e The window 4 swings. For example, as shown in the figure, the transmitted SOR light 8 and the Be window 4 move in synchronization from the upper end to the lower end of the wafer 6 to scan the pattern.

The Be window 4 does not change its shape because it simply moves downward. However, the shape of the SOR light 8 that passes through here is Be at the position corresponding to the upper end of the wafer.
Although the size of the window 4 is large, the area shape gradually decreases as the scanning moves, and the area shape decreases at the lower end facing position to the extent shown in the drawing, which does not hinder wafer exposure.

Considering the horizontal focusing degree of the SOR light 8, the area shape of the SOR light 8 is large at the position corresponding to the upper end, so that the focusing degree is small and the exposure amount for the wafer 6 is small. At the position corresponding to the lower end portion, the area shape of the SOR light 8 becomes small, the degree of converging in the horizontal direction becomes large accordingly, and the exposure amount for the wafer 6 becomes large.

As shown in FIG. 1 again, the control circuit 8 simultaneously outputs control signals to the rocking drive sources of the toroidal X-ray mirror 3 and the Be window 4 to control the speed at the same time. That is, these rocking speeds are controlled by multiplying the reciprocal of the estimated SOR light intensity change rate. Thereby, the S transmitted through the Be window 4 coming from the shape structure of the toroidal X-ray mirror 3.
The in-plane intensity of the OR light 8 on the wafer 6 is made uniform and the exposure unevenness can be corrected. The characteristics of this device are conceptually as shown in FIGS. 5 (A), (B), and (C).

That is, as shown in FIG.
As the vertical position of the window 4 changes from a low position to a high position, the horizontal focusing degree of X-rays passing therethrough tends to increase.

As shown in FIG. 3B, the rocking speeds of the toroidal X-ray mirror 3 and the Be window 4 with respect to the vertical position of the Be window 4 are constant (a) as in the conventional case, and the above-described implementation. There is a case (b) in which correction is performed as in the example. Here, the rocking speed is reduced as the vertical position is raised.

As shown in FIG. 6C, when the swing speed is kept constant (a) as in the conventional case, the exposure amount changes from a vertical low position to a high vertical position, As a result, exposure unevenness is caused. On the other hand, by controlling the swing speed as in the above embodiment, the exposure amount can be kept constant regardless of the change in the vertical position.

The shape change of the SOR light 8 due to the use of the toroidal X-ray mirror 3 and the accompanying removal of the exposure unevenness are not only calculated but also calculated.
Actually, even if an exposure experiment such as uniform velocity fluctuation is performed and the control condition is obtained from the result, the same or higher correction can be performed.

In the above embodiment, the rectangular B
The e-window 4 is used to correspond to the curved shape of the SOR light 8 that passes therethrough, but the present invention is not limited to this, and as shown in FIG. It may be the Be window 4A. It is to be noted that the oscillating drive in synchronism with the toroidal X-ray mirror 3 and the speed control at the same time are the same as in the above embodiment.

Furthermore, as shown in FIG. 4, a Be window 4B having a sufficient shape area over the scanning range of the SOR light 8 may be used. At this time, naturally, it is not necessary to drive the Be window 4B to swing. However, for the toroidal X-ray mirror 3, there is no change in the need for the swing drive in which a control signal is issued from the control circuit 7 and speed control is performed under a predetermined condition. In addition, various modifications can be made within the scope of the present invention.

[0038]

As described above, according to the first invention, the SOR light is extracted from the SOR ring to the beam line, and the toroidal X-ray mirror that swings to expand the exposure area is installed in the beam line. A Be (beryllium) window that oscillates in synchronization with the oscillation of the toroidal X-ray mirror is arranged at the end of the beam line, and the SOR light is estimated for the oscillation speed of the Be window and the toroidal X-ray mirror. The control means was provided for controlling the speed at the same time by multiplying the reciprocal of the intensity change rate.

According to the second aspect of the invention, the SOR light is extracted from the SOR ring to the beam line, and a toroidal X-ray mirror that oscillates to expand the exposure area is installed in the beam line. Be (beryllium)
A window is arranged and a control means for controlling the swing speed of the toroidal X-ray mirror by multiplying it by the reciprocal of the estimated SOR light intensity change rate is provided.

In any of the inventions, when the SOR light extracted from the SOR ring to the beam line is condensed and reflected by the toroidal X-ray mirror and is swung to expand the exposure area, the exposure due to the change of the SOR light shape is performed. This has the effect of correcting unevenness and improving exposure accuracy.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an X-ray lithography apparatus showing an embodiment of the present invention.

FIG. 2 is an explanatory view of a change in the visual field range of the toroidal X-ray mirror and the Be window which swing in the same embodiment.

FIG. 3 is a view for explaining a change in the visual field range of a toroidal X-ray mirror and a Be window that oscillate with each other, showing another embodiment.

FIG. 4 is a view for explaining a change in the visual field range in which only the toroidal X-ray mirror is swung, showing still another embodiment.

5A, 5B, and 5C are exposure characteristic diagrams of an X-ray lithography apparatus.

[Explanation of symbols]

1 ... SOR ring, 2 ... Beam line, 3 ... Toroidal X-ray mirror, 5 ... Mask, 6 ... Wafer, 4 ... Be (beryllium) window, 7 ... Control means (control circuit).

Claims (2)

[Claims] 1. A high intensity SOR (synchrotron radiation X)
Line) An SOR ring as a light source, an ultra-high vacuum beam line that extracts the SOR light from this SOR ring, and a SOR light that is installed in this beam line to collect and reflect the SOR light and oscillate to expand the exposure area. A toroidal X-ray mirror, a Be (beryllium) window that is arranged at the end of the beam line and oscillates in synchronization with the oscillation of the toroidal X-ray mirror to extract X-rays and expose a masked wafer. X-ray lithography comprising a Be window and control means for multiplying the swing speed of the toroidal X-ray mirror by the reciprocal of the estimated rate of change in SOR light intensity to simultaneously control the speed to correct exposure unevenness. apparatus. 2. A high intensity SOR (synchrotron radiation X)
Line) An SOR ring as a light source, an ultra-high vacuum beam line that extracts the SOR light from this SOR ring, and a SOR light that is installed in this beam line to collect and reflect the SOR light and oscillate to expand the exposure area A toroidal X-ray mirror, a Be (beryllium) window arranged at the end of the beam line for exposing the masked wafer by extracting X-rays, and an SOR light for estimating the swing speed of the toroidal X-ray mirror. An X-ray lithographic apparatus comprising: a control unit that multiplies the reciprocal of the intensity change rate to control the exposure unevenness.