JPS61202436A - Exposing apparatus - Google Patents

Abstract

PURPOSE:To accurately align by using an excimer laser as a light source, and commonly using the projecting units of optical systems for transferring and exposing a mask pattern on the surface of a wafer and for aligning an alignment mark, thereby transferring in a high resolution. CONSTITUTION:A luminous flux from an excimer laser 1 is divided into two fluxes by luminous flux dividing means 2. One flux is emitted by an illumination optical system 3 to a mask pattern 4 and projected by a projecting system 5 on the surface of a wafer 6. The other flux is emitted through a reflecting mirror 8, a translucent mirror 9 and a reflecting mirror 10 by an alignment optical system 11 to the alignment mark on the pattern 4, and projected by the system 5 near the alignment mark on the wafer 6. Then, both marks are focused by the system 11 and a focusing system 13 on an image sensing tube 14 to detect the relative positional relationship of the marks by detecting means 15. Drive means 15 drives an X-Y stage on the basis of the result to match the pattern 4 to the wafer 6.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention is applicable to the process of repeatedly transferring and exposing a mask pattern in which a fine pattern such as an electronic circuit is formed onto a wafer surface to fabricate a semiconductor t-n. The present invention relates to an exposure apparatus that can align a mask pattern and a wafer with high precision.

(Conventional Technology) Recent semiconductor technology has continued to increase the degree of integration and miniaturization of electronic circuits, and optical exposure methods are also expanding their range further due to the development of high-resolution lenses, etc.6. When using such exposure equipment in semiconductor manufacturing to transfer and print the circuit pattern of a mask or reticle onto the wafer surface,
The resolution line width of the circuit pattern printed on the wafer surface is proportional to the wavelength of the light source.
A short wavelength light source in the LrV ) region is used.

However, these light sources have low output in the deep ultraviolet region, and the photosensitivity of the photosensitive material coated on the wafer surface is also low, so they have drawbacks such as long exposure times and low throughput. there were.

On the other hand, in recent years, excimer (txelmar) lasers, which are high-output light sources whose oscillation wavelength is in the deep ultraviolet region, have been studied in various fields. This excimer laser is very effective in exposure equipment for semiconductor manufacturing because it has high brightness, excellent monochromaticity, and little coherence.

Generally, in the manufacturing process of semiconductor devices, a process is adopted in which mask patterns having different text structures are transferred onto the wafer surface in several layers by repeating the actual training process. When an excimer laser is used as a light source and the oscillation wavelength of the excimer laser is shortened to miniaturize printed lines 1), it is necessary to align the mask pattern and the wafer with high precision each time. It's coming. However, since conventional methods have used visible light, it takes time to align the mask pattern and the wafer with high precision each time it is printed, resulting in a decrease in throughput.

(Objective of the present invention) The present invention uses an excimer laser as a light source to transfer a mask pattern onto a wafer surface with high resolution.
We aim to achieve high throughput costs by aligning the mask pattern and wafer topology with high precision and at high speed, and provide nine exposure devices.

(Main features of the present invention) When a mask pattern on which a pattern of an electronic circuit or the like is formed is illuminated with a light beam from an excimer laser through an illumination optical system, and the mask pattern is transferred and exposed onto a wafer surface, A part of the light beam from the excimer laser is split by a light beam splitting means, and the light beam is guided to the alignment mark trap provided on the mask pattern surface, and alignment between the mask pattern and the wafer is performed using the alignment mark or alignment mark. This was done by scanning the image of the mark.

Other features of the invention are described in the Examples.

(Example) FIG. 1 is a schematic diagram of an optical system according to an embodiment of the present invention.

In the same figure, 1 is an excimer laser, and one 5t of the light beam from the excimer laser 1 is divided into 5t by the light beam splitting means 2.
Divide the luminous flux into nine parts. Among these, the light beam reflected by the light beam splitting means 2 illuminates the mask pattern 4 by the illumination optical system 3.

The mask pattern 4 is projected onto the surface of the sea urchin 66 by the projection system 5. On the other hand, the nine beams passing through the beam splitting means 2 are reflected by a reflecting mirror 8, and are sent to the alignment optical system 1) via a semi-transmissive mirror 9 and a reflecting mirror 10. The mask alignment mark provided on the fourth surface of the mask pattern is irradiated. The mask alignment mark is projected by the projection system 5 near the wafer alignment mark provided on the surface of the wafer 6 . The alignment marks for both the mask alignment mark and the wafer alignment mark projected onto the surface of the sea urchin are projected onto the projection system 5 and the alignment optical system 1.
) and the imaging system 13K] For example, an image is formed on the imaging surface of the imaging tube 14, and the relative positional relationship between both alignment marks is electrically scanned and detected by the detection means 15. Based on the output signal from the detection means 15, the XY stage 7 on which the lever 6 is placed is driven by the drive means 16.
The mask pattern 4 and the wafer 6 are aligned by t-IK movement.

To align the mask alignment mark and the wafer alignment mark in this embodiment, in principle, it is possible to use the method already proposed by Oboromoto Motode in Japanese Patent Application Laid-Open No. S3-135654.

FIG. 2, @, and 0 are explanatory diagrams of the aligned state of alignment marks proposed in Japanese Patent Application Laid-Open No. 53-135654, respectively.

Alignment for the mask as shown in Figure 2! -ri2
5 is a part of the mask pattern 4 consisting of two black lines 45 inclined horizontally and parallel to each other.
b and mark 25m1.25b1 is a mark 25az -25b formed by two black lines parallel to each other in a direction orthogonal to each other.
The marks 25a1 and 25a2 constitute one alignment mark, and the marks 25b1 and 25b
2 constitutes the other alignment mark.

In addition, each mark of mask pattern 4 is 25 m long on wafer 6.
'v-/26a1+26a2 of the alignment mark 26 for sea urchin/1, which is composed of a single black line parallel to and corresponding to 25m, 25b, and 25b2.
+26b1 *26b2 are provided. And marks 26m, 26m on the 16th surface of Unino,
26b and 26b2 are marks 25m1 and 25m2 on the fourth side of the mask pattern, respectively.25b and 25b2
The mask pattern 4 and the wafer 6t are relatively displaced so that they are located parallel to each other approximately in the middle of the wafer 6t, thereby aligning them.

In auto-alignment using a television camera as in this embodiment, the alignment mark images of both the mask/(turn number and wafer 6) are scanned by scanning lines s and s' of the image pickup tube as shown in Figure 2 Ω. Time to electrically scan and scan between each black line tU tU2・t3・t4・t1′・1.(
・ti・tjt-detected, and if these are not all equal, adjust the positions of both according to the deviation, and finally scan time t.

t2 * t39t4 + tt tt t3', t
, : are all made equal.

In this embodiment, the alignment between the mask pattern and Uni-No is performed by detecting the scattered light and diffracted light from the edges of the alignment marks, as proposed in Japanese Patent Application Laid-open No. 135654/1982, without using an image pickup tube. Also good. In this case, the alignment mark position a on the mask pattern surface is
It is necessary to arrange a scanning means for t-i scanning, for example between the light source and the alignment optical system.

In this embodiment, the illumination optical system 3 includes a means for spatially achieving uniformity of light amount such as a light integrator, an exposure amount control means such as a shutter, and speckles that occur when using a light source with good coherence. It has a means for converting it into incoherent F to remove it.

In this embodiment, when scanning the alignment mark optically, EXI! It is preferable to irradiate the alignment mark with the beam from the laser in the form of an elongated sheet-like beam cross section because this increases the amount of scattered light and improves the S/N ratio.

In this embodiment, it is also possible to use the so-called professional exposure method in which the mask pattern and the wafer are transferred and exposed with a slight interval t without using a projection system. By using a common projection system for both the optical system for transfer exposure onto one surface of Unino and the optical system for matching the alignment marks on both sides, and by using a short wavelength from the excimer laser, It is possible to transfer the pattern onto the surface of the sea urchin with high resolution, and furthermore, errors in the imaging performance of the projection system due to environmental changes immediately appear as errors in the imaging performance of the alignment marks.
Therefore, highly accurate matching is always possible.

Also, since the mask pattern and the wafer are aligned using a short wavelength light beam from an excimer laser, when alignment is performed using scattered light or diffracted light from the edge of the alignment mark, the angle of the diffracted scattered light from the edge This reduces the amount of diffracted and scattered light that enters the signal detection system in the alignment device, improving the S/N ratio and enabling high-accuracy and high-speed alignment.

One more exi! Since the light beam from the laser is divided into two parts and used for transfer exposure and alignment, the exposure apparatus can be made smaller.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an optical system according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram of an alignment mark according to the present invention. Dividing means, 3 is an illumination optical system, 4 is a mask pattern, 5 is a projection system, 6 is a wafer, 7 is an XY stage, 1) is an alignment optical system, 1
3 is an imaging system, 14 is an image pickup tube, 15 is a detection means, and 16 is a drive means.

Claims (2)

[Claims] (1) When a mask pattern on which a pattern such as an electronic circuit is formed is illuminated with a light beam from an excimer laser via an illumination optical system, and the mask pattern is transferred and exposed onto a wafer surface, the light beam from the excimer laser A part of the light beam is divided by a beam splitting means and guided to an alignment mark provided on the mask pattern surface, and the alignment mark or the image of the alignment mark is optically or electrically aligned between the mask pattern and the wafer. 1. An exposure apparatus characterized in that the exposure is performed by scanning. (2) The mask pattern is projected and exposed onto a wafer surface via a projection system, and the mask pattern and the wafer are aligned via the projection system. The exposure apparatus described.