JPH09266158A - Semiconductor aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make uniform illumination distribution of illumination light and reduce the attenuation of light intensity for high output and high efficiency, by employing a light source that produces plasma discharge with torus-shaped intensity distribution in a light emitting tube, and taking out light with the assumption of a central axis of the plasma discharge of the torus-shaped light intensity of the light source being used as an optical axis. SOLUTION: When an AC current is applied from an oscillator 14 to a coil of a light source 1, a magnetic field is formed for the light emitting tube 11 over the entire periphery in the direction of winding of the coil, and electric discharge is produced on discharge gas in the light emitting tube 11 such that the discharge wounds around the magnetic field. Thereupon, plasma discharge of torus-shaped intensity distribution is produced in the light emitting tube 11 along the direction of winding of the coil. A diameter of a light emission cross section of the plasma discharge is about 8mm. Light is derived through optical means 2 using as an optical axis the central axis of the plasma distribution of the torus-shaped intensity distribution of the light source 1. A semiconductor wafer material 22 is irradiated with the light. Hereby, illumination distribution of the illumination light is made uniform, and attenuation of the light intensity is reduced for high output power and high efficiency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor exposure apparatus used for manufacturing semiconductor devices.

[0002]

2. Description of the Related Art Conventionally, in a lithography process in manufacturing a semiconductor device, a semiconductor exposure apparatus is used, and a semiconductor surface is irradiated with light having a wavelength of about 400 nm or less to form an integrated circuit. The light source in this step is required to have functions such as a desired output value of ultraviolet rays, a sufficiently narrow spectral line width, and stable output over time.

As such a light source, for example, a high pressure mercury lamp has been used so far. This is 254n of mercury
This is because exposure is performed using a spectrum of m, 365 nm, or the like. In such a light source, its size is made as small as possible to make it a point light source for practical use, and a grating,
The surface of the semiconductor is irradiated with light through an optical system such as a mirror.

By the way, it is known that when the light from the point light source is irradiated through the optical system, the illuminance at the central portion of the irradiated light becomes high and the illuminance at the peripheral portion becomes low.
In this way, if the illuminance distribution of the irradiation light is non-uniform, defects will occur in semiconductor manufacturing.

Therefore, in the conventional semiconductor exposure apparatus, after the light from the light source is taken out as almost parallel light by the reflecting mirror, it is converted into an almost donut-shaped light intensity distribution in the middle of the optical system, and this donut shape is obtained. By condensing and irradiating the light, the illuminance difference between the central portion and the peripheral portion of the irradiation light is reduced, and the illuminance distribution of the irradiation light is made uniform.

[0006]

By the way, in the semiconductor exposure apparatus, in order to obtain temporal uniformity of exposure,
In order to shorten the exposure time, higher output is desired.

However, if the input power of the light source is simply increased, the mercury vapor becomes supersaturated, the spectral line width increases, the spatial resolution of exposure decreases, and even when the mercury vapor pressure is suppressed. Output saturation does not always lead to output increase.

Further, it was confirmed that the light intensity is attenuated in the process of converting the light once extracted as the point light source into the light having the donut-shaped intensity distribution by the optical system.

An object of the present invention is to provide a semiconductor exposure apparatus which can make the illuminance distribution of irradiation light uniform and reduce the attenuation of light intensity by an optical system to achieve high output and high efficiency.

[0010]

A semiconductor exposure apparatus according to claim 1 is provided with an arc tube, at least a discharge gas sealed in the arc tube, and an electrode means for generating a plasma discharge having a donut-shaped intensity distribution in the arc tube. A light source having: and an optical means for extracting light with the central axis of plasma discharge having a donut-shaped intensity distribution of the light source as an optical axis.

Then, a light source for generating a plasma discharge having a donut-shaped intensity distribution is used in the arc tube, and light is extracted with the central axis of the plasma discharge having the donut-shaped intensity distribution of the light source as the optical axis. By doing so, the light does not have to be converted into light having a donut-shaped intensity distribution, the illuminance distribution of the irradiation light becomes uniform, and the attenuation of the light intensity by the optical system is reduced to achieve high output and high efficiency.

Further, mercury may be enclosed in the arc tube together with the discharge gas. The optical means is composed of a reflecting mirror and a lens system.

A semiconductor exposure apparatus according to a second aspect is the semiconductor exposure apparatus according to the first aspect, wherein the electrode means is a coil disposed around the arc tube, and high frequency power is supplied to this coil. , A plasma discharge having a donut-shaped intensity distribution is generated in the arc tube.

A semiconductor exposure apparatus according to a third aspect is the semiconductor exposure apparatus according to the first or second aspect, wherein the arc tube has a spherical shape, and high efficiency can be achieved.

A semiconductor exposure apparatus according to a fourth aspect is the semiconductor exposure apparatus according to the first or second aspect, wherein the arc tube has a flat shape and can be miniaturized.

A semiconductor exposure apparatus according to a fifth aspect is the semiconductor exposure apparatus according to the first or second aspect, in which the arc tube has a donut-shaped discharge path, and the resonance line of the ultraviolet ray is self-absorbed in the central portion. Can be eliminated, resulting in higher efficiency.

A semiconductor exposure apparatus according to claim 6 is the semiconductor exposure apparatus according to any one of claims 1 to 5.
It is provided with a shutter capable of blocking the light extracted from the light source to the optical means, and can selectively irradiate and block the light.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

1 to 3 show a first embodiment. FIG. 1 is a configuration diagram of a semiconductor exposure apparatus, FIG. 2 is an explanatory diagram of a light source, and FIG. 3 is an explanatory diagram illustrating an operation of the light source.

In FIG. 1, the semiconductor exposure apparatus comprises a light source 1, optical means 2, shutter 3 and the like.

The light source 1 is, as shown in FIGS. 2 and 3,
It has a light emitting tube 11, and this light emitting tube 11 is made of transparent quartz glass and has a spherical shape, and a discharge space 12 is formed therein. The inner diameter of the arc tube 11 is about 15 mm, and no phosphor or the like is applied. The arc tube 11 is filled with about 30 mg of mercury and a discharge gas such as 100 Torr of argon gas.

A coil 13 as an electrode means is provided around the arc tube 11 with a gap of about 3 mm from the outer circumference of the arc tube 11.
Are wound around. An alternating current of about 400 W and a frequency of 13.56 MHz is applied to the coil 13 from an oscillator 14.

The optical means 2 is, as shown in FIG.
Light is taken out with the central axis of plasma discharge having a donut-shaped intensity distribution, which will be described later, of the light source 1 as the optical axis, and is located below the coil 13 disposed around the arc tube 11 of the light source 1 in a direction orthogonal to the winding direction. A reflecting mirror 15 is obliquely arranged, and an integrator 16 and a reflecting mirror 17 are arranged obliquely with respect to an optical axis reflected by the reflecting mirror 15 so that the received light is once focused and then spread. Furthermore, with respect to the optical axis reflected by the reflecting mirror 17,
A filter 18, a condenser lens 19 that focuses light, a photomask 20 that forms the light into a desired pattern, and a reduction lens 21 that reduces the light are provided. A semiconductor wafer material 22 is arranged below the reduction lens 21, and the ultraviolet light passing through the reduction lens 21 exposes the semiconductor wafer material 22.

The shutter 3 comprises a light source 1 and an optical means 2.
It is arranged so as to be able to move forward and backward between the reflection mirror 15 and the reflection mirror 15, and transmits light from the light source 1 to the optical means 2 when retracted, and blocks the light when entering.

Next, the operation of the first embodiment will be described.

In FIG. 3, when an alternating current is applied from the oscillator 14 to the coil 13 of the light source 1, a magnetic field a as shown by a broken line is formed on the arc tube 11 along the winding direction of the coil 13. Discharge occurs in the discharge gas in the arc tube 11 so as to be wrapped around this magnetic field a. Then, a plasma discharge p having a donut-shaped intensity distribution is generated in the arc tube 11 along the winding direction of the coil 13. The diameter of the emission cross section of this plasma discharge p is about 8 mm.

Then, the optical means 2 extracts light with the central axis of the plasma discharge p of the doughnut-shaped intensity distribution of the light source 1 as the optical axis, and irradiates the semiconductor wafer material 22.

As described above, the light source 1 for generating the plasma discharge p having the donut-shaped intensity distribution is used in the arc tube 11, and light is extracted with the central axis of the plasma discharge p having the donut-shaped intensity distribution of the light source 1 as the optical axis. As a result, the optical system does not have to convert the light into a donut-shaped intensity distribution as in the conventional case,
The illuminance distribution of the irradiation light can be made uniform, and the attenuation of the light intensity by the optical system can be reduced to achieve high output and high efficiency.

When the plasma discharge p having the donut-shaped intensity distribution is produced by the light source 1, the loss amount of about 23% when the light having the donut-shaped intensity distribution is produced by the optical system can be reduced.

Next, FIG. 4 shows a second embodiment. FIG. 4 is a perspective view of the light source.

In this embodiment, the light emitting tube 11 of the light source 1 is formed in a donut shape, and the doughnut-shaped discharge path 31 is formed in the light emitting tube 11. Then, if a coil is arranged around this arc tube 11 and electricity is applied, as in the first embodiment, plasma discharge p is generated inside the arc tube 11 along the donut shape of the arc tube 11. .

As described above, when the arc tube 11 has a donut shape, the self-absorption of the resonance line of the ultraviolet ray disappears in the central portion. It has been confirmed by experiments that the efficiency of the arc tube 11 having a diameter of 15 mm having a hole of about 5 mm is improved by about 12% as compared with that of a tube having no hole.

Next, FIG. 5 shows a third embodiment. FIG. 5 is a perspective view of the light source.

In this embodiment, the arc tube 11 of the light source 1 is formed in a circular shape and has a flat peripheral shape, and a flat discharge space 12 is formed in the arc tube 11. And this arc tube
When a coil is arranged around 11 to energize in the same manner as in the first embodiment, plasma discharge p is generated inside arc tube 11 along the donut shape of arc tube 11.

Thus, if the arc tube 11 has a flat shape, the efficiency can be improved and the size can be reduced.

[0036]

According to the semiconductor exposure apparatus of the first aspect, a light source for causing plasma discharge having a donut-shaped intensity distribution is used in the arc tube, and the central axis of the plasma having the donut-shaped intensity distribution of the light source is used as an optical axis. Since the light is taken out, it does not have to be converted into light having a donut-shaped intensity distribution by an optical system as in the past, and the illuminance distribution of the irradiation light can be made uniform, and
It is possible to reduce the attenuation of the light intensity due to the optical system to achieve high output and high efficiency.

According to the semiconductor exposure apparatus of the second aspect,
In addition to the effect of the semiconductor exposure apparatus according to claim 1, by supplying high-frequency power to a coil arranged around the arc tube, a plasma discharge having a donut-shaped intensity distribution can be generated in the arc tube. .

According to the semiconductor exposure apparatus of the third aspect,
In addition to the effects of the semiconductor exposure apparatus according to the first or second aspect, the arc tube has a spherical shape, and can be highly efficient.

According to the semiconductor exposure apparatus of the fourth aspect,
In addition to the effects of the semiconductor exposure apparatus according to the first or second aspect, the arc tube has a flat shape and can be miniaturized.

According to the semiconductor exposure apparatus of the fifth aspect,
In addition to the effects of the semiconductor exposure apparatus according to the first or second aspect, since the arc tube has a donut-shaped discharge path, self-absorption of the resonance line of the ultraviolet ray at the central portion is eliminated, and the efficiency can be further increased.

According to the semiconductor exposure apparatus of the sixth aspect,
In addition to the effects of the semiconductor exposure apparatus according to any one of claims 1 to 5, since the shutter that can shield the light extracted from the light source to the optical means is provided, the irradiation and the shielding of the light can be selectively performed.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a semiconductor exposure apparatus showing a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a light source according to the same embodiment.

FIG. 3 is an explanatory diagram illustrating an operation of the light source according to the above embodiment.

FIG. 4 is a perspective view of a light source showing a second embodiment of the present invention.

FIG. 5 is a perspective view of a light source showing a third embodiment of the present invention.

[Explanation of symbols]

 1 light source 2 optical means 3 shutter 11 arc tube 13 coil as electrode means 31 discharge path

Claims (6)

[Claims] 1. A light source having a light emitting tube, at least a discharge gas sealed in the light emitting tube, and an electrode means for generating a plasma discharge having a donut-shaped intensity distribution in the light emitting tube; a plasma discharge having a donut-shaped intensity distribution of the light source. An optical means for extracting light with the central axis of the optical axis as an optical axis; and a semiconductor exposure apparatus. 2. The semiconductor exposure apparatus according to claim 1, wherein the electrode means is a coil arranged around the arc tube, and high-frequency power is supplied to this coil. 3. The semiconductor exposure apparatus according to claim 1, wherein the arc tube has a spherical shape. 4. The semiconductor exposure apparatus according to claim 1, wherein the arc tube has a flat shape. 5. The semiconductor exposure apparatus according to claim 1, wherein the arc tube has a donut-shaped discharge path. 6. The semiconductor exposure apparatus according to claim 1, further comprising a shutter capable of blocking the light extracted from the light source to the optical means.