JPS63140527A - Transcriber with alignment mechanism - Google Patents

Abstract

PURPOSE:To realize the simplification and size reduction of the construction of a transcriber by sharing a part for two alignment optical systems. CONSTITUTION:1st alignment light 11 which has a wavelength same as an exposing wavelength is transmitted through a dichroic mirror 13 and applied to a mask mark 9 and a wafer mark 7. The light reflected by the mark 7 is applied again to the mark 9. The light obtained from the mark 9 is reflected by the dichroic mirror 13 and detected by an optoelectric transducer 27 through a shared part 10. On the other hand, 2nd alignment light 12 composed of illuminating light which has a wavelength different from the exposing wavelength enters a projection lens 3 through the transparent part 6 of a mask 2 and illuminates the wafer mask 7. The mark 7 is composed of a deflection lattice and a part of the light deflected by the mark 7 enters a turning-back mirror 8 and, after the light path length is corrected, is applied to the mark 9 and the light transmitted through the mark 9 is detected by an optoelectric transducer 37 through the shared part 10. From the outputs of the two optoelectric transducers 27 and 37, the relative discrepancy between the marks 7 and 9 is detected. With this constitution, the difference in alignment between the two marks can be calibrated with a high accuracy.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention provides an IC circuit pattern formed on a mask.
Regarding a pattern transfer device that performs projection exposure on YEVA 1-,
In particular, the present invention relates to a transfer apparatus having a wafer/mask alignment mechanism.

(Prior Art) In recent years, in the manufacture of ICs such as semiconductor devices, circuit patterns have become increasingly finer, and devices for transferring patterns having a line width of 1 μm or less have also been developed. In such an apparatus, for example, a photosensitive material (photoresist) is applied onto a wafer and a mask image is printed onto the wafer to form a pattern. In this case, the wafer and mask (reticle) on which the integrated circuit is formed
It is necessary to position the two with respect to each other extremely accurately, and many alignment methods have been proposed for this purpose.

For example, in a device that installs a reduction projection lens between a wafer and a mask and projects the pattern on the mask onto the wafer in reduction, the marks on the mask and the marks on the wafer or the mark on the table can be projected using the reduction projection lens. A so-called TTL alignment optical system, which is an optical system that measures the positional relationship of each mark by observing through the mark, has been adopted as a highly accurate positioning method.

Ideally, TTL alignment is performed using the same wavelength as the exposure wavelength, but for various reasons, for example, He-
This is often carried out using a wavelength that does not expose (sensitize) marks, such as Ne laser light.

In this case, in order to perform compensation IF due to chromatic aberration between the exposure wavelength and the alignment light wavelength, for example,
As shown in No. 8, a folding mirror is provided to adjust the optical path length. However, in such a structure, a positional deviation error occurs due to the precision in mounting the folding mirror. This is because a small angular error in the mirror shifts the reflected light, which then enters the reticle mark.

As a method for solving the above-mentioned problem, as shown in FIG. It is conceivable to provide a second alignment optical system 52 that performs alignment and calibrate the output of the second alignment optical system 52 with the output of the first alignment optical system 51. In addition, 1 in the figure is a condenser lens,
2 is a mask, 3 is a reduction projection lens, 4 is a wafer, and 5 is an X
A Y table, 7 is a mark on the wafer or table-1, 8 is a folding mirror, and 9 is a mark on a mask.

In this device, the positional relationship of the marks 7.9 can be detected with high precision by the first alignment optical system 51. Furthermore, the positional relationship of the marks 7.9 can also be measured by the second alignment optical system 52;
This measurement information may contain errors. Therefore, position information is obtained by the first and second alignment optical systems under the same conditions between the mask and the wafer, and the respective position information is compared. The amount of deviation of this positional information is measured by the second alignment optical system 52 u! Since this is a difference of It becomes possible to perform position detection.

However, this type of device has the following problems. That is, as shown in FIG.
Since the measurement position in the alignment optical system is different,
1E It becomes difficult to perform accurate position correction calibration. It is very difficult in terms of space to arrange the first and second alignment optical systems in the same direction in order to bring the measurement positions closer together. Furthermore, since two TTL alignment optical systems are required, there are problems such as an increase in the size of the alignment optical systems.

(Problem to be solved by the invention) Conventionally, when alignment is performed using light with a wavelength different from the exposure wavelength, measurement errors cannot be avoided, and two types of alignment optical systems with different wavelengths have to be prepared. No. However, providing two alignment optical systems
It is also difficult in terms of space and has the problem of being large. Furthermore, there were other problems such as poor position correction calibration accuracy for both.

The present invention was made in consideration of the above circumstances, and its purpose is to make it possible to miniaturize two alignment optical systems and to accurately calibrate the position correction of both. An object of the present invention is to provide a transfer device having a positioning mechanism that can perform mask/wafer positioning with high precision and improve pattern transfer accuracy.

[Configuration of the Invention] (Means for Solving Problems) The gist of the present invention is to simplify and downsize the configuration by sharing a part of two alignment optical systems.

That is, the present invention provides an apparatus that projects and exposes a pattern formed on a mask onto a wafer through a projection lens, and transfers the mask pattern onto the wafer. A first alignment optical system detects the relative position of the wafer, and a second alignment optical system detects the relative position of the mask and wafer using light of a wavelength different from the exposure wavelength.
The alignment optical system is provided with an alignment optical system, and some optical members of each of the first and second alignment optical systems are shared.

(Function) With the above configuration, it is possible to configure a small-sized TTL alignment optical system with a simple structure by co-integrating parts of the two types of TTL alignment optical systems. Furthermore, by integrating the two, the alignment marks will inevitably be placed very close to each other or coincidentally, so when calibrating the difference in alignment between the two, it will be possible to correct them with high precision. Become.

In addition, in the future, it will be necessary to align masks and wafers with higher viscosity, so the number of optical systems for alignment will be increased from the conventional two to three or four, corresponding to each of the four sides of the chip. The need arises. Therefore, it is extremely effective to reduce the size by including an optical system.

(Example) Hereinafter, details of the present invention will be explained with reference to illustrated embodiments.

FIG. 1 is a schematic diagram showing a pattern transfer device according to an embodiment of the present invention. In the figure, 1 is a condenser lens, 2
is a mask, 3 is a reduction projection lens, 4 is a wafer, and 5 is a table. By illuminating the mask 2 through the condenser lens 1, the pattern of the mask 2 is reflected by the projection lens 3.
The mask pattern is projected onto the wafer 4 and transferred onto the wafer 4.

The first alignment light 11 having the same wavelength as the exposure wavelength passes through a dichroic mirror 13, which will be described later, and irradiates the mask mark 9 and the wafer mark 7. Here, the Daimiroku mirror 13 acts as a half mirror for the first alignment light. The light reflected by the mark 7 is irradiated onto the mark 9 again. Then, the light obtained from the mark 9 is reflected by the dichroic mirror 13, and is detected by the photoelectric conversion element 27 via the mirror 6 section 10, which will be described later. Then, from the output of the photoelectric conversion element 27, mark 7.9
In other words, the relative positional shift between the mask and the wafer is detected.

On the other hand, illumination light with a wavelength different from the exposure wavelength (for example, He-
The second alignment light 12 using Ne laser light) is
It enters the projection lens 3 through the transparent part (window part) 6 of the mask 2 and illuminates the wafer mark 7. Mark 7 is a diffraction grating mark, and part of the light diffracted here enters return mirror 8, corrects the optical path length, and then irradiates mark 9. The light that passes through this is reflected by dichroic mirror 13. It is reflected and detected by the photoelectric conversion element 37 via the common part 10. Then, the relative positional shift between the mask and the wafer is detected from the output of the photoelectric conversion element 37.

The sharing section 10 is configured as shown in FIG. 1st
The second alignment light 14 reflected by the dichroic mirror 21 passes through a lens (first lens) 22, becomes parallel, and proceeds to the second dichroic mirror 23 side. Here, the mirror 23 transmits the first alignment light but not the second alignment light.
The alignment light is reflected. Therefore, the second alignment light 14, which has become a parallel light, is reflected by the mirror 23 and is passed through the photoelectric conversion probe 37 by the condenser lens 36.
is imaged. The output of the photoelectric conversion cable 37 is supplied to a signal processing circuit 38, which outputs a mask-wafer relative position error signal.

On the other hand, the first alignment light 13 reflected by the dichroic mirror 21 is not parallel light even though it passes through the lens 22 because the lens 22 is designed to obtain parallel light with respect to the first alignment light. For example, it becomes a diverging light. This diverging light passes through a dichroic mirror 23 and passes through a lens (second lens) 24, thereby becoming parallel light.

This parallel second alignment light is condensed by a condenser lens 26 via a beam modulator 25 and imaged onto a photoelectric conversion element 27 . The output signal of the photoelectric conversion element 27 is then supplied to a signal processing circuit 28, which outputs a mask-wafer relative positional shift signal.

Here, the dichroic mirror 21 and lenses 22, 24
are fixed to the same casing 20, and the dichroic mirror 23, condensing lenses 26, 36, etc. are fixed to a separate part from the casing. The casing 20 is movable in the direction shown by the arrow in the figure by a drive mechanism consisting of a motor 30, screws 29, and the like. Therefore, when the position of the mask mark to be detected differs depending on the size of the device element, that is, the chip size, the casing 20 can
It works by sliding the casing and bringing the dichroic mirror 21 above the approximate mark.

It should be noted that the accuracy of the caging movement is not required as much as shown in the left, and it is sufficient that a light beam having positional information of the wafer mark and the reticle mark is inputted to each sensor. Furthermore, even if the casing is moved, the light entering the light receiving elements 27 and 37 will always be imaged, so it does not matter how many ships there are. In other words, the first
Since the alignment light 13 and the second alignment light 14 are each guided to each sensor from a portion that becomes parallel light, it is possible to correspond to alignment with any chip size.

The marks 7.9 each have a first alignment mark and a second alignment mark, and are formed, for example, as shown in FIG. 3.

That is, the slit-like patterns 32a, 32b and the slit-like white pattern 3 are attached to the first alignment optical system.
2c is formed and the collapsing gyrus Frl? is formed for the second alignment optical system. Quintuplet patterns 31a and 31b are formed.

In this case, in the first alignment optical system, the beam modulator 25 alternately selects the slit patterns 32a and 32b as images incident on the photoelectric conversion probe 27. As a result, the photoelectric conversion element 27 obtains a detection signal as shown in FIG. 4, and positioning by zero point detection becomes possible.

Note that the slit-like white pattern 32c is used for ITV observation and the like. Regarding the second alignment optical system, in addition to vibrating the light irradiated to the mark 7.9 (alternatingly illuminating the diffraction grating patterns 31a and 31b), the detection signal of the photoelectric conversion element 37 is synchronously detected. , an output similar to that shown in FIG. 4 is obtained.

Note that the marks 7.9 do not necessarily require a pair of marks for the first alignment and for the second alignment, and may be a single mark. In this case, although the accuracy of position detection is lower, the beam modulator, means for vibrating the beam, etc. are not required.

Thus, according to this embodiment, the relative positions of the mask and wafer can be detected by the first and second alignment optical systems in the same manner as in the past, and by calibrating these positional corrections, the second alignment optical system can be detected. The alignment optical system can detect the relative positional deviation of the mask and wafer with high precision.

In this case, since the light-receiving sides of the first and second alignment optical systems are shared and integrated, the alignment optical system can be made smaller and simpler, and the position correction calibration can be made more accurate, resulting in higher pattern transfer accuracy. Effects such as being able to measure ``2'' are added by 7B+.

That is, conventionally, in order to measure the relative position between a wafer and a mask, as described above, a first alignment optical system using the same wavelength as the exposure light and a second alignment optical system using a different wavelength from the exposure light are required. Met. Furthermore, a mask alignment optical system was required to accurately align the mask to a certain fixed position. Such an optical system generally has to be accommodated in a limited space between a condenser lens and a mask of a projection exposure apparatus. Therefore, spatial constraints are required.

In contrast, in this embodiment, by configuring the optical system so that a part of the first and second alignment optical systems are shared, the structure becomes extremely simple and there is no spatial problem. Furthermore, since the optical system is shared, errors during alignment measurement are reduced. In a conventional projection exposure apparatus, the first and second alignment optical systems are provided separately, and the second alignment optical system, which uses a wavelength different from that of the exposure light, uses its own mark to align the mask to a certain position. used for The first alignment optical system using exposure light uses its own mark and is used to correct the relative relationship with the second alignment. This embodiment has the advantage that this alignment can be shared and that adjustment can be easily performed with a simple configuration compared to conventional alignment optical systems.

Furthermore, with this structure, each alignment mark needs to be placed close to each other or as the same mark. This improves alignment accuracy.
It has the advantage of That is, conventionally, the mask alignment mark was fixed on the mask surface, and was provided at a fixed position regardless of whether the chip size was increased or decreased. For this reason, the first and second alignment marks are provided separately,
For this reason, it is directly affected by errors during mark production.

In this method, since the marks are common or close to each other,
There is almost no difference in alignment, and highly accurate alignment is possible. Further, there is an advantage that offset correction of TTL alignment can be performed accurately.

Note that the present invention is not limited to the first embodiment described above, and can be implemented with various modifications without departing from the gist thereof. For example, the alignment marks do not necessarily need to be provided separately for the first or second alignment, and may be the same mark. Furthermore, the shape of the mark is not limited to a slit or a diffraction grating, and can be changed as appropriate depending on the specifications. Further, as the alignment method, a synchronous detection method, a differential slit method, or others may be selected as appropriate. Furthermore, it is also possible to use a prism or the like in place of the dichroic mirror.

[Effects of the Invention] As detailed above, according to the present invention, the first alignment optical system uses light of the same wavelength as the exposure wavelength, and the second alignment optical system uses light of a wavelength different from the exposure wavelength. Since a part of the optical system is integrated with the optical system, the two alignment optical systems can be miniaturized, and both can be calibrated accurately. Therefore, the mask and wafer can be aligned with high precision, and pattern transfer precision can be improved.

[Brief explanation of the drawing]

- Fig. 1 is a schematic configuration diagram showing a pattern transfer device according to an embodiment of the present invention, Fig. 2 is a diagram showing the main part configuration of the 1 U marking device, and Fig. 3 is an example of marks used in the above device. FIG. 4 is a signal waveform diagram showing the relationship between the amount of positional deviation and the detection output, and FIG. 5 is a schematic configuration diagram showing a conventional device. 1... Condenser lens, 2... Mask, 3...
Projection lens, 4... wafer, 5... table, 6...
...Light transmission window, 7...Wafer mark, 8...Folding mirror, 9...Mask mark, 10...Shared part, 1
1.13...first alignment light, 12.14...
- Second alignment light, 21... first dichroic mirror, 22 first lens, 23... second dichroic mirror, 24... second lens, 27. 37
...Photoelectric conversion element. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 3 Figure 4

Claims (7)

[Claims] (1) In an apparatus that projects and exposes a pattern formed on a mask onto a wafer through a projection lens and transfers the mask pattern onto the wafer, light of the same wavelength as the exposure wavelength is used to align the mask and wafer. a first alignment optical system that detects the position; and a second alignment optical system that detects the relative position of the mask and wafer using light of a wavelength different from the exposure wavelength; 1. A transfer device having a positioning mechanism, characterized in that a common part is provided in which a part of the optical members of each of the alignment optical systems is shared. (2) A transfer device having an alignment mechanism according to claim 1, wherein the shared portion is a shared portion of the light receiving portion side of the first and second alignment optical systems. . (3) The shared portion includes a first dichroic that reflects the first alignment light having the same wavelength as the exposure wavelength obtained through the wafer and the mask, as well as the second alignment light having a wavelength different from the exposure wavelength. a mirror, a first lens that parallelizes the second alignment light obtained via the mirror, and a first alignment light obtained via the mirror and the lens.
a second lens that parallelizes the alignment light; and a second dichroic mirror disposed between the first and second lenses that transmits the first alignment light and reflects the second alignment light. 3. A transfer device having a positioning mechanism according to claim 2. (4) The first dichroic mirror and the first and second lenses are fixed in a predetermined relationship to an integral casing, and this casing is arranged in the radial direction of the mask or in the direction of the mark depending on the size of the mask pattern or the position of the mark. 4. A transfer device having a positioning mechanism according to claim 3, wherein the transfer device is movable in the tangential direction of the mask. (5) After placing the wafer and forming a reference mark on an XY table that can be moved in a plane, and positioning the mark at a predetermined position, first alignment light having the same wavelength as the exposure wavelength or 2. A transfer device having an alignment mechanism according to claim 1, wherein the mask and wafer are aligned using second alignment light of a different wavelength. (6) A transfer device having an alignment mechanism according to claim 1, wherein the output of the second alignment optical system is calibrated based on the output of the first alignment optical system. . (7) The first and second alignment optical systems perform alignment using the same mark or adjacent marks formed on the mask and wafer. A transfer device with the alignment mechanism described.