JPS62114222A - Exposing apparatus - Google Patents

Abstract

PURPOSE:To obtain an inexpensive exposing apparatus which has high accuracy and small size by detecting marks for positioning a pattern, focusing, correcting an oblique amount and positioning a reticle position all by a set of mark detectors. CONSTITUTION:An illumination optical system having a light source 13 and a lens 12 for exposing an original picture pattern 14, a reticle 6 and its finely moving mechanism 9, a projecting lens 4, an XY stage 11 for securing a wafer 1 coated with photosensitizer 2 by a stationary base 31, and mark detectors 24, 25 mounted on the back side of the wafer 1 are provided. A plurality of fine through holes 21 are formed at the wafer 1, the holes 21 are disposed at the positions for providing a target mark 3 to be used for positioning, and 2, 3 holes are provided at the peripheries of respective exposing regions. The detectors 24, 25 are secured to the back side of the wafer 1 in the entire apparatus. The wafer 1 can move in X-, Y- and Z-axes directions, and the reticle 6 can axially finely move in x-, y-, theta-, z-axes by the mechanism 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an exposure apparatus for forming and transferring fine patterns of semiconductor elements and the like.

[Background of the invention]

In the manufacturing process of semiconductor devices, etc., it is necessary to transfer fine patterns with high precision, and it is also necessary to precisely align the pattern on the substrate (wafer) formed in the previous process with the newly transferred pattern. There is. As a device for transferring fine patterns, a mask (on which the original pattern of the circuit is drawn) is used.
or reticle) with a projection lens to the same magnification or reduction,
There are projection exposure apparatuses that perform exposure transfer using ultraviolet light, and X-ray exposure apparatuses that use X-rays or the like for transfer.

The configuration of a conventional projection exposure apparatus, as shown in FIG. A fine mover Na10 for focusing, an XY stage 11 for two-dimensionally moving and positioning the wafer 1, an illumination optical system 12, 13 for exposing the circuit pattern 14 on the reticle 6, and pattern positioning. It consists of a mark position detector 8 for performing the following steps. The positioning performed when transferring a circuit pattern using the conventional device described above is performed using target marks 3 formed on the surface of the wafer 1.
is projected onto the reference mark 15 on the surface of the reticle 6 using the projection lens 4, and the mark position detector 8 is used to align the reticle 6 and the target mark 3 so that their mutual positions match. This was done by moving the wafer 1 relatively. However, the manufacturing process for semiconductor devices generally consists of ten or more steps, and the shape and material of the wafer surface change with each step. Therefore, the target mark used for alignment changes similarly. Furthermore, the photoresist 2 is coated on the surface of the wafer in each step, and the thickness of the coated film may vary. These factors reduce the contrast of the target mark 3 detected by the mark position detector 8, resulting in a reduction in detection accuracy. As a result, pattern positioning accuracy has deteriorated.

As mentioned above, the conventional apparatus has the disadvantage that there is a limit to highly accurate pattern alignment because it is affected by the manufacturing process. In addition, in order to improve the accuracy of alignment,
Although alignment is required for each chip, it is necessary to prevent the detection optical system of the mark position detector from interfering with the light flux that exposes the circuit pattern. For this reason, the detection optical system has a complicated structure, and as a result,
The drawback is that there is a limit to the accuracy of detection.

Incidentally, related devices of this type include, for example, Japanese Patent Application Laid-Open No. 144270/1982, US Pat. No. 4,355,892, and the like.

[Purpose of the invention]

An object of the present invention is to obtain an exposure apparatus that can perform highly accurate positioning and transfer without being affected by the manufacturing process.

[Summary of the invention]

An exposure apparatus according to the present invention is an exposure apparatus that exposes and transfers an original image pattern onto a substrate coated with a photosensitive agent, in which a plurality of minute through holes are provided in a specific area of the substrate, and a plurality of minute through holes are provided in the periphery of the back surface of the through holes. a mark detector that simultaneously detects a plurality of alignment marks and a reference mark on the original image pattern or a projected image of the reference mark through the through hole;
By installing it on the back side of the board, it is possible to align the original pattern with the board, focus during exposure, and correct the amount of tilt.

This is to align the mask.

[Embodiments of the invention]

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

FIG. 1 is a configuration diagram showing an embodiment of an exposure apparatus according to the present invention, FIG. 2 is a partial outside w1 view of a wafer used in the above embodiment,
Fig. 3 is an explanatory diagram of the wafer and mark detection unit, Fig. 4 is an illustration of alignment marks, Fig. 5 is an explanatory diagram of detection signals obtained by the mark detector, and Fig. 6 is an illustration of reticle positioning. The explanatory diagram, FIG. 7, is a diagram showing the relationship of marks in reticle positioning. The embodiment shown in FIG. 1 is an example in which the present invention is applied to a reduction projection exposure apparatus, and includes an illumination optical system consisting of a light source 3 and a lens 12 for exposing an original image pattern 14, a reticle 6 and its fine movement mechanism 9. , a projection lens 4, an XY stage 11 on which a wafer 1 coated with a photosensitive agent 2 is fixed on a fixing table 31, and mark detectors 24 and 25 installed on the back side of the wafer 1. 2
7 and 29 are illumination devices for reference marks 15 and 15', respectively. A plurality of minute through-holes 21 are provided in the wafer 1, and the through-holes 21 are located at positions where target marks 3 used for alignment are provided, and 2.3 minute holes are formed at the periphery of each exposure area. They are set up individually. On the back side of the wafer 1, mark detectors 24, 25 are fixed to the entire apparatus. Further, the wafer 1 is movable in the X, Y, and Z directions, and the reticle 6 can be finely moved in the four-axis directions of x, y, and θ-2 by a fine movement mechanism 9.

In the present exposure apparatus configured as described above, a method of pattern positioning will be described first.

FIG. 2 is an external view showing a portion of the wafer 1 on which pattern alignment is performed. Circuit pattern 3 of each exposure area on wafer 1
Although the through holes 21-1, 21-2, etc. are provided in the peripheral portion 32 of No. 3, the peripheral portion 32 may be a scribe area. The through-holes 21-1, 21-2, etc. are formed after the first exposure and development processes are completed. FIG. 3 shows a sectional view of the through holes 21-1, 21-2, etc. formed in the wafer 1.

Around the through hole 21, the thickness t of the wafer 1 is left on the back side,
For example, the dimension D is approximately twice the dimension d of the through hole 21 (O=2d
) form a hole. A target mark 3.3' for positioning is formed in the peripheral portion 34 of the through hole. By forming the target mark 3.3' at the above position,
The target mark 3.3' is subject to the manufacturing process.

The alignment is performed by first determining the mutual positions of the reference pattern 15 on the reticle 6 and the target mark 3.3' on the wafer 1. The projected image 26 of the reference mark 15 is the through hole 2
The image is formed on the same surface as the surface of wafer 1. The reference mark 15 and the target mark 3 on the wafer 1 are shown in FIG. 4, but these two marks are merely examples, and various other mark shapes are possible.

The projected image 26 of the reference mark 15 and the target mark 3 are detected by a mark detection optical system 22.23 and a mark detector 24.2.
5.

The mark detectors 24 and 25 perform two-dimensional signal processing to calculate the mutual positions of the reference mark 15 and the target mark 3. If the XY coordinates are calculated in each of the through holes 21-1 and 21-2 in the above process, the mutual positional relationship ΔX, ΔY between the circuit pattern 33 on the wafer 1 and the circuit pattern to be exposed and transferred next.

ΔZ can be found. Alignment is performed by slightly moving the reticle 6 and the wafer 1 relative to each other so that ΔX, ΔY, and ΔZ become zero. Also, due to atmospheric pressure fluctuations, the projection lens 4
If the magnification of 26.2 changes, the above two reference marks 26.2
Since the distances between the reticle 6' and the target mark 3.3' are not equal, the magnification is corrected by slightly moving the reticle 6 in the optical axis direction (Z direction) so that the distances are the same.

Note that the portion of the wafer 1 where the target mark 3 is formed
It is desirable that the thickness t be within the depth of focus of the mark detection optical system. However, if it is necessary to increase t, this can be solved by making the mark detection optical system a bifocal system.

Next, a method of focusing during exposure and transfer and correcting the tilt amount of the exposure area will be explained. Through holes 1 around the exposure area 33, e.g. 21-1, 21-2, 21-4
The mark detector 24 detects the target mark in the area. As shown in FIG. 5, the point where the edge of the signal obtained by detection rises steeply as shown by a solid line 35 is the in-focus position. Focusing and tilt amount correction are performed by slightly moving the stage 10.11 that fixes the wafer 1 in the optical axis direction and in the tilt direction so that the edge of the mark signal becomes steep as shown in FIG.

Next, a method for positioning the reticle 6 at a predetermined position in the exposure apparatus will be explained. This operation is exposure.

This must be done prior to transcription. As shown in Figure 6
Positioning marks 36.37 are provided on the YZ stage 10.11 at the same height as the surface of the wafer 1.

To perform positioning, first move the xYZ stage 10.11 so that the reference mark 15.15' on the reticle 6 is imaged at the position of the positioning mark 36.37.
The mark detector 24 or 25 detects the relative position of the projected image of the reference mark ts, 15' and the positioning mark 36, 37. As shown in Figure 7, the basic monk mark 15
．． 15' projected image 26.26' and positioning mark 36.
There are two locations with 37 located a distance apart from each other. Position coordinates ΔXL, ΔXR, ΔyL, Δθ of the reticle 6 obtained from the relative positions determined at each of the two positions
Positioning is performed by finely moving the fine movement mechanism 9 to which the reticle 6 is fixed in the four axis directions of x, y, θ, and 2 so that R becomes zero.

As mentioned above, in the past, the positioning of the reticle 6 was performed using a separately provided position detector (FIG. 8, 7) and the fine movement mechanism 9, but in the present invention, the positioning of the wafer 1 and the focus during exposure are performed. In addition to alignment and tilt amount correction, mask alignment can be performed using the same mark detector.

Although the above embodiments have been described with respect to a projection exposure apparatus that uses light, effects similar to those described above can be obtained in other exposure apparatuses that use X-rays, ion beams, or the like.

〔Effect of the invention〕

As described above, the exposure apparatus according to the present invention is an exposure apparatus that exposes and transfers an original image pattern onto a substrate coated with a photosensitive agent, and includes a plurality of minute through holes provided in a specific area of the substrate.
A mark detector that simultaneously detects a plurality of alignment marks provided around the back surface of the through hole and a reference mark on the original pattern or a projected image of the reference mark through the through hole is installed on the back side of the substrate. By providing the target mark in the first layer, the target mark used for the first alignment will not be deformed during the manufacturing process, and the target mark formed in the first layer can be used until the final process without the resist covering the surface. Since there is no influence of generated interference fringes, etc., the accuracy of one positioning is improved. Furthermore, high accuracy can be achieved in focusing without being affected by the wafer surface condition.

Furthermore, as mentioned above, pattern alignment, focus adjustment, tilt amount correction, and mark detection for reticle positioning can all be performed with one set of mark detectors, which simplifies the device configuration and results in , it is possible to obtain a high-precision, compact, and low-cost exposure apparatus.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment of an exposure apparatus according to the present invention, FIG. 2 is a partial external view of a wafer used in the above embodiment, FIG. 3 is an explanatory diagram of the wafer and mark detection section, and FIG. 4 5 is a diagram showing alignment marks, FIG. 5 is an explanatory diagram of a detection signal obtained by a mark detector, FIG. 6 is an explanatory diagram of reticle positioning, and FIG. 7 is a diagram showing the relationship of marks in reticle positioning. , FIG. 8 is a block diagram showing a conventional exposure apparatus. 1... Substrate (wafer) 2... Photosensitive agent 3.3'
...Positioning mark 14...Original image pattern 15, 15'...Reference mark 21.21-1.21-2...Through hole 24.2
5...Mark detector

Claims (2)

[Claims] (1) In an exposure device that exposes and transfers an original image pattern onto a substrate coated with a photosensitive agent, a plurality of minute through-holes are provided in a specific area of the substrate, and a plurality of minute through-holes are provided around the back surface of the through-hole. An exposure apparatus characterized in that a mark detector is provided on the back side of the substrate for simultaneously detecting an alignment mark and a fiducial mark on the original image pattern or a projected image of the fiducial mark through the through hole. (2) The above alignment mark should be at the same height as the board in XY
2. The exposure apparatus according to claim 1, wherein the exposure apparatus is a positioning mark provided at a position on a stage.