JPH09199411A - Aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the decline in an alignment accuracy caused by the reflection of alignment light. SOLUTION: X ray L1 is cast on a mask M1 and a wafer W1 through an opening O1 of an aperture 1 and alignment light F1 to be used for alignment of the mask M1 and the wafer W1 is cast on the mask M1 and the wafer W1 through an aperture blade 11 of the aperture 1. By applying an antireflection coating 1a on the surface of the aperture blade 1, the reflection of the alignment light F1 is avoided and the decline in alignment accuracy caused by a ghost is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus that uses exposure light having a short wavelength such as X-rays.

[0002]

2. Description of the Related Art In recent years, as semiconductor devices have been highly integrated, semiconductor elements have been further miniaturized, and a semiconductor element of 256 MDRAM is required to have a line width of 0.25 μm and a semiconductor element of 1G DRAM is required to have a line width of 0.18 μm. For the overlay accuracy of the baking patterns, for example, in the case of a semiconductor element of 256M DRAM, 80 nm,
In the case of the semiconductor element of 1G DRAM, it is 60 nm.

In order to print such a miniaturized pattern on a substrate such as a wafer with high overlay accuracy, X-rays of shorter wavelength are used instead of i-rays or KrF laser light which are widely used as exposure light at present. (Synchrotron radiation)
It has been proposed to avoid deterioration of resolution due to diffraction by using, for example. FIG. 4 shows a conventional example of a step-and-repeat type proximity exposure apparatus in which X-rays are used as exposure light. The wafer W held on the positioning stage S ₀ is shown in FIG.
The ₀ of the surface is photosensitive resist is applied, exposed by X-rays L ₀ emitted through the mask M _0, thereby, the circuit pattern P ₀ of the mask M ₀ is transferred, is baked. The optical path of the X-ray L _0, aperture 101 to block the unwanted peripheral portion of the X-ray L ₀ is arranged, around the predetermined exposure region of the wafer W ₀ is serves prevented from being exposed. The aperture 101 is composed of four aperture blades made of a plate material having a sufficient light blocking property to block X-rays, for example, a glass plate having a thickness of about 200 μm.

The mask M ₀ is composed of an X-ray transmission film that transmits X-rays and an X-ray light shielding film such as Au (gold) deposited on the mask, and has a predetermined circuit pattern in the circuit pattern transfer area of the wafer W _0. has a circuit pattern P ₀ for transferring the, also on the outside of the circuit pattern P _0, the mask M ₀ and the wafer W alignment marks a ₀ for alignment used in the alignment (alignment) of ₀ A transfer alignment mark (not shown) for transferring an alignment mark for the next lithography together with the circuit pattern to a scribe line on the periphery of the circuit pattern transfer region of the wafer W ₀ is provided.

Before and during the exposure with the X-ray L ₀ , the alignment mark A for aligning the mask M ₀ is used.
Alignment between the mask M ₀ and the wafer W ₀ is performed using the alignment mark of the wafer W ₀ which is baked by ₀ and the previous lithography. This alignment is irradiated with alignment light F ₀ emitted from the alignment optical system (not shown) disposed on the side near the optical path of the X-ray L ₀ to the wafer W ₀ through mask M _0, the position of the mask M ₀ those alignment marks a ₀ for mating drives the positioning stage S ₀ of the wafer W ₀ to overlap the alignment mark of the wafer W _0, the side near thus alignment light F ₀ is the optical path of the X-ray L ₀ for the alignment optical system is irradiated is transmitted through the respective aperture blades of the aperture 101, as the material of each aperture blade which transmits the alignment light F ₀ to shield the exposure light L _0, Nachi Suwa glass and X-ray It is common to choose durable plastics.

[0006]

However, according to the above-mentioned conventional technique, when the alignment light for aligning the wafer and the mask is transmitted through the aperture blade, the alignment light of the alignment light on the incident side and the alignment light on the exit side are respectively generated. There is an unsolved problem that a part is reflected and becomes a ghost, which causes a significant error in the output of the alignment optical system, which makes it difficult to perform highly accurate alignment. That is, when light passes through the boundary surface between two substances having different refractive indices, a part thereof becomes reflected light, so that reflected light occurs when the alignment light enters the aperture blade and when it exits from the aperture blade. The reflected light enters the alignment optical system as a ghost and causes an error in the detected value.

Further, the alignment light is transmitted through the alignment mark of the mask and applied to the alignment mark of the wafer, and the light reflected by the alignment light is moved backward to the alignment optical system to detect the positional deviation between the wafer and the mask. is there. Therefore, the alignment light passes through the aperture blade twice, and each time the above-mentioned ghost is generated by the reflected light, which causes a large error in the detection value of the alignment optical system. In addition, the energy loss (attenuation) of the alignment light due to reflection is also large, which tends to significantly deteriorate the reliability of the detection value of the alignment optical system.

The present invention has been made in view of the above-mentioned unsolved problems of the prior art, and prevents the alignment light from being reflected when the light is transmitted around the opening of the opening means such as the aperture. An object of the present invention is to provide an exposure apparatus capable of improving the reliability of the output of an optical system and accurately aligning an original plate such as a mask with a substrate such as a wafer.

[0009]

In order to achieve the above object, the exposure apparatus of the present invention comprises an exposure optical system for transferring a transfer pattern of an original onto a substrate by the exposure light irradiated through the opening of the opening means. The alignment means has an alignment means for aligning the original plate and the substrate with alignment light transmitted through a predetermined portion around the opening of the opening means, and the alignment light is provided on at least one surface of the predetermined portion of the opening means. It is characterized in that it is provided with an antireflection film for preventing the above reflection.

An antireflection film may be provided on both surfaces of a predetermined portion of the opening means.

[0011]

The function of preventing the alignment light from passing through the opening means is prevented by the antireflection film. As a result, it is possible to avoid the occurrence of ghost and the attenuation of the alignment light due to the reflection of the alignment light, improve the reliability of the output of the alignment means, and improve the alignment accuracy of the original plate and the substrate. When a finer transfer pattern is transferred and printed using exposure light of a short wavelength such as X-ray, the alignment of the substrate and the original plate requires extremely high precision. Therefore, the alignment light transmitted through the opening means is reflected. It is especially important to prevent

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an exposure apparatus according to one embodiment. As shown in FIG. 1A, a wafer W ₁ which is a substrate is held and a known step movement and alignment are performed. a positioning stage S _1, aperture 1 a opening means for shielding the remaining unwanted peripheral portion except for the necessary portion of the X-ray L ₁ is a exposure light generated from the light source Q ₁
And an exposure optical system including a mask stage 2 and the like for positioning a mask M ₁ as an original plate in the vicinity of the wafer W ₁ , and the aperture 1 has four aperture blades as shown in FIG. 11 is provided, and an opening O ₁ through which a necessary portion of the X-ray L ₁ is passed is formed in the center thereof. The mask stage 2 holds a mask holding substrate 2b which is integral with the mask M ₁ via a mask reinforcing frame 2a, and the mask M ₁ is made of an X-ray transparent film which transmits X-rays and an Au which is adhered thereto. A circuit pattern P ₁ which is a transfer pattern for transferring a predetermined circuit pattern to the circuit pattern transfer region of the wafer W _{1 is formed} of an X-ray shielding film such as (gold), and a mask is provided outside the transfer pattern. An alignment mark A ₁ for alignment used for aligning M ₁ and the wafer W ₁ , and a transfer alignment for transferring the alignment mark for the next lithography together with the circuit pattern to the scribe line of the wafer W _1. A mark is provided.

[0014] exposure of the wafer W ₁ by X-ray L ₁ is, as described above, the unnecessary peripheral portion of the X-ray L ₁ is blocked by the aperture blade 11 of the aperture 1, the mask M ₁ is passed through only the necessary portion To the circuit pattern P
₁ and the alignment mark for the next lithography are transferred to the wafer W ₁ .

In this way, before the start of the exposure cycle for performing the exposure with the X-ray L ₁ and during the exposure, the mask M described above is used.
Wafer W ₁ by using the alignment marks A ₁ for alignment _1, the alignment marks that are printed on the scribe line of the wafer W ₁ by a previous lithography
And mask M ₁ are aligned. This alignment is performed by irradiating the wafer W ₁ with the alignment light F ₁ generated from the alignment optical system 3 which is the alignment means arranged near the side of the optical path of the X-ray L ₁ through the mask M ₁ .
In which the alignment marks A ₁ for alignment of the mask M ₁ drives the positioning stage S ₁ of the wafer W ₁ so as to overlap the alignment mark of the wafer W _1. Since the wafer W ₁ and positioning of the mask M ₁ is performed by the alignment light F ₁ emitted from the side close to the optical path of the X-ray L _1, and each aperture blade 11 of the aperture 1 blocks the X-ray L ₁ Alignment A material that transmits the light F ₁ , such as a glass plate or Pyrex, is used.

The alignment optical system 3 is generally 2
Are trapezoidal or 4 Taihai set, and each aperture blade 11 of the aperture 1, the aperture stage 1 is freely parallel to reciprocate the positioning stage S ₁ of the wafer W ₁
1a and a drive unit (not shown) composed of a DC servo motor or a stepping motor controlled by an encoder or the like, by which each aperture blade 11 is advanced and retracted, the size of the opening O ₁ of the aperture 1 is controlled with high accuracy. To do.

Each aperture blade 11 has an antireflection film 1 on at least an edge portion facing the opening O ₁ of the aperture 1.
a so that the alignment light F ₁ is configured to prevent reflection on the incident side when the alignment light F ₁ passes through each aperture blade 11 of the aperture 1.

The antireflection film 1a is an aperture blade 1
Material having a smaller refractive index than the material of No. 1, such as cryolite (aluminium fluoride), thiolite (Na _x A
l _y F _z), fluorinated magnesium (MgF ₂₎ such as an antireflection film of a single layer consisting of the formed lambda / 4 film with, or has the above lambda / 4 film are laminated two or three layers It is a multilayer antireflection film.

In the alignment of the wafer W ₁ and the mask M ₁ described above, when the alignment light F ₁ passes through each aperture blade 11 of the aperture _1, a part of the alignment light F ₁ is reflected on the incident side and the emission side thereof, Although there is a possibility that a ghost that deteriorates the alignment accuracy may be generated and the alignment light F ₁ may be attenuated, in the present embodiment, the antireflection film 1a is provided on the incident side of each aperture blade 11.
By providing the above, the alignment light F ₁ is prevented from being reflected and the alignment accuracy is improved. In this embodiment, the antireflection film was provided only on one surface of each aperture blade of the aperture, but if necessary, the antireflection film is provided on both the entrance side and the exit side of the alignment light, that is, both surfaces of each aperture blade. May be.

According to this embodiment, by preventing the reflection of the alignment light when passing through the aperture, the occurrence of ghost and the attenuation of the alignment light can be prevented, and the reliability of the detection value of the alignment optical system can be greatly improved. You can As a result, the accuracy of alignment between the wafer and the mask can be improved, and an exposure apparatus suitable for production of semiconductor devices with advanced miniaturization can be realized.

Next, an embodiment of a method of manufacturing a semiconductor device using the above-mentioned exposure apparatus will be described. FIG. 2 shows semiconductor devices (semiconductor chips such as IC and LSI, liquid crystal panels,
2 shows a flow of manufacturing a CCD, a thin-film magnetic head, a micromachine, and the like. In step S11 (circuit design), the circuit of the semiconductor device is designed. In step S12 (mask production), a mask on which the designed circuit pattern is formed is produced. On the other hand, in step S13 (wafer manufacturing), a wafer as a substrate is manufactured using a material such as silicon. Step S14 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the prepared mask and wafer. The next step S15 (assembly) is called a post-process, and is a process of forming a semiconductor chip using the wafer manufactured in step S14, and includes processes such as an assembly process (dicing and bonding) and a packaging process (chip encapsulation). including. In step S16 (inspection), the semiconductor device manufactured in step S15 undergoes inspections such as an operation confirmation test and a durability test. Through these steps, a semiconductor device is completed and shipped (step S17).

FIG. 3 shows a detailed flow of the wafer process. In step S21 (oxidation), the surface of the wafer is oxidized. In step S22 (CVD), an insulating film is formed on the wafer surface. In step S23 (electrode formation), electrodes are formed on the wafer by vapor deposition. Step S24
In (ion implantation), ions are implanted into the wafer. In step S25 (resist processing), a photosensitive agent is applied to the wafer. In step S26 (exposure), the circuit pattern of the mask is printed and exposed on the wafer by the exposure apparatus described above. In step S27 (developing), the exposed wafer is developed. In step S28 (etching), portions other than the developed resist image are removed. In step S29 (resist stripping), unnecessary resist after etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer.
By using the manufacturing method of this embodiment, it is possible to manufacture a highly integrated semiconductor device, which has been conventionally difficult to manufacture.

[0023]

Since the present invention is configured as described above, it has the following effects.

It is possible to prevent the alignment light from being reflected when the light is transmitted around the opening of the opening means such as the aperture, and the accuracy of the alignment between the wafer and the mask can be greatly improved. As a result, it is possible to transfer and print the circuit pattern of the mask with extremely high overlay accuracy.

[Brief description of drawings]

FIG. 1 shows an exposure apparatus according to an embodiment, (a)
Is a partial schematic elevational view showing the main part thereof, and FIG. 6B is a partial plan view seen from the line AA of FIG.

FIG. 2 is a flowchart showing manufacturing steps of a semiconductor device.

FIG. 3 is a flowchart showing a wafer process.

FIG. 4 is a partial schematic elevational view showing a main part of an exposure apparatus according to a conventional example.

[Explanation of symbols]

 1 Aperture 1a Antireflection Film 2 Mask Stage 3 Alignment Optical System 11 Aperture Blade

Claims (3)

[Claims] 1. An exposure optical system for transferring a transfer pattern of an original onto a substrate by exposure light irradiated through an opening of the opening means, and alignment light for transmitting a predetermined portion around the opening of the opening means. An alignment means for aligning the original plate and the substrate is provided, and an antireflection film for preventing reflection of the alignment light is provided on at least one surface of the predetermined portion of the opening means. Exposure equipment. 2. The exposure apparatus according to claim 1, wherein an antireflection film is provided on both surfaces of a predetermined portion of the opening means. 3. The exposure apparatus according to claim 1, wherein the exposure light is an X-ray.