JP2723600B2 - X-ray exposure apparatus and X-ray exposure method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a semiconductor manufacturing apparatus, and more particularly to an X-ray exposure apparatus and an X-ray exposure method for performing X-ray exposure.

(Prior Art) In recent years, with the increase in density and speed of semiconductor integrated circuits,
The pattern line width of integrated circuits tends to be reduced to 70% in about three years.

With the further integration of large-capacity memory elements (for example, 4MDRAM), devices with a 16-Mbit capacity and the like have been designed with a 0.5 μm rule. For this reason, even higher performance is required for printing equipment, and the minimum transferable line width is 0.5μ.
The high performance of less than m is beginning to be required. Therefore, a stepper using light in the X-ray region (7 to 14 °) as an exposure light source wavelength is being developed.

The mask structure used in these X-ray exposure apparatuses includes, for example, as shown in FIG. 3, an X-ray transmitting film 31 made of an X-ray transmitting material and a holding frame 32 for holding the film in tension.
On the X-ray transmission film 31, there are formed alignment marks and X-ray absorbers 33 arranged with a desired geometric arrangement.

The method of forming the X-ray transmission film 31 is roughly classified according to whether the material used is an organic thin film or an inorganic thin film. For the former, a material that has a high X-ray transmittance and is transparent to visible light is selected, and films such as polyimide, polyamide, and mylar are preferred because of their Young's modulus, thermal expansion coefficient, surface roughness, and the like. Used. These X-ray permeable films 31 are held in tension by a holding frame 32 with an adhesive, and these X-ray permeable films 31 are fixed in a form having sufficient flatness.

On the other hand, when an inorganic material is used as the X-ray transmitting film, as shown in FIG. 4, a film of a silicon compound of about 2 μm, particularly silicon nitride or silicon carbide, is formed on the silicon wafer 42 ′ by a chemical vapor deposition method or the like. 41 is formed to have a slight tensile stress. Next, the silicon wafer 42 'on which the film 41 has been deposited is removed from the back surface by etching only a necessary region (a region for transmitting X-rays), and the inorganic thin film 41 is held in tension on the silicon wafer 42'. A mask blank is obtained. However, in this state, since the silicon wafer 42 'is thin, the strength is small and it is inconvenient for handling and practical use. Therefore, the reinforcing member 42 is usually bonded and used with an adhesive.

In any of the above cases, it is desirable that the holding frame 32 (FIG. 3) or the reinforcing body 42 (FIG. 4) be sufficiently strong, thermally stable and light. Conventionally, quartz glass, borosilicate glass (Pyrex),
Stainless steel and the like have been used, but recently, ceramic sintered bodies have come to be used to satisfy the above conditions well.

An X-ray exposure apparatus using a mask structure as described above is used to place an X-ray source, a chamber 1 for partitioning an X-ray exposure area, and an exposure target material 2 such as a silicon wafer at a predetermined position, as schematically shown in FIG. A mask chuck means (mask chuck) 5 for superposing a wafer chuck 3 fixed on the substrate and a mask structure 4 at a predetermined position on a material to be exposed is mainly formed.

(Problems to be Solved by the Invention) However, the ceramic materials and the like forming the holding frame and the reinforcing body as described above are materials having excellent strength and thermal stability, but generally have high insulation properties. The inside of the X-ray exposure apparatus is in a vacuum or helium atmosphere so that the intensity of X-rays does not decrease. As a result, when X-ray exposure is performed in this atmosphere, static electricity and secondary electrons emitted from the X-ray absorber are charged on the mask surface of the mask structure, and the mask surface comes into contact with the material to be exposed and discharge occurs. However, there is a problem that the mask surface is damaged or damaged, and furthermore, the resist on the material to be exposed is overexposed due to the effects of emitted photoelectrons and secondary electrons, and the dimensional accuracy and the like are inconsistent when forming a fine pattern. The problem that arises has arisen.

Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art, and provide an X-ray exposure apparatus and an X-ray exposure apparatus having excellent antistatic properties and dimensional accuracy
It is to provide a line exposure method.

(Means for Solving the Problems) The above object is achieved by the present invention described below.

That is, the present invention provides an X-ray exposure apparatus comprising: an X-ray generation unit; a unit for fixing an X-ray exposure target material at a predetermined position; and a mask holding unit for fixing an X-ray mask at a predetermined position. An X-ray exposure apparatus and an X-ray exposure method, wherein a conductive portion is formed on each of a mask and the mask holding means, and these conductive portions are electrically contacted as necessary.

(Operation) By forming conductive portions on both the X-ray mask and the means for gripping the X-ray mask, and electrically connecting these conductive portions as necessary, charging during exposure is prevented, and Since photoelectrons and Auger electrons generated at the time of exposure are effectively removed, X-ray exposure with proper and excellent dimensional accuracy is realized.

(Example) Hereinafter, an example of the present invention is described using a drawing.

Embodiment 1 FIG. 1 is a diagram schematically illustrating a cross section of an X-ray exposure apparatus of the present invention.

This exposure apparatus has an electrical contact between one side surface of the X-ray mask 4 and a V block 6 constituting a part of the mask chuck 5, and the V block unit 6 and the chamber 1 are electrically connected. 1 is the ground potential. The inside of the chamber is a helium atmosphere, and the pressure is about 100 torr.

FIG. 2 is a view showing a state where the V block 26 and the X-ray mask M are mounted on the mask stage 30 (FIG. 3). Here, the mask holding frame 22 abuts on the V block 26, and when the mask holding frame 22 and the V block 26 are substantially in close contact, a desired position excluding the rotational component of the mask is obtained. Reference numeral 29 denotes a pin fitted or inserted into the notch of the mask, and one end of the notch and a part of the pin 29 abut to position the mask in the rotational direction. Further, by mounting an earth spring 25 from a part of the V block 26 and making contact with the end face of the mask, photoelectrons and Auger electrons generated from the X-ray absorber made of heavy metal during X-ray exposure are formed on the X-ray transmission film. Absorbed by the mask electrode layer 24. The earth spring 25 used here is made of phosphor bronze, and the contact end is curved so that the part in contact with the X-ray mask does not damage the X-ray mask surface, but the material and shape are conductive. ,
This is not the case unless the X-ray mask is damaged.

FIG. 3 is a sectional view taken along line AA 'of the X-ray mask structure shown in FIG. Reference numeral 33 denotes an X-ray absorber, which is made of gold in the present embodiment, but may be made of any material such as tantalum or tungsten which has a large absorption for exposure X-rays. 31 is the absorber 33
Although polyimide is used for the X-ray transmission film that supports, the inorganic films such as silicon nitride (SiN), silicon carbide (SiC),
It may be boron nitride (BN) or a composite film of an organic film and an inorganic film. Reference numeral 32 denotes a holding frame that holds the X-ray transmission film 31. Gold was deposited on the entire surface of the X-ray mask to a thickness of 100 ° to form an electrode layer 34. By performing X-ray exposure using the X-ray mask in the X-ray exposure apparatus of the present invention, the charge generated at the time of exposure is prevented, so that the X-ray mask does not come into contact with the wafer and the X-ray absorber No damage to the layer.

Embodiment 2 FIG. 4 is a cross-sectional view of an X-ray mask according to another embodiment, and a cross-sectional view of a V block and a ground spring taken in.

After depositing an inorganic thin film 41 of silicon nitride, silicon carbide, boron nitride, etc. to a thickness of about 4 μm on a silicon substrate 42 ′ having a thickness of 2 mm, an absorber pattern made of gold is formed on the inorganic thin film 41.
43 is formed on the entire surface of the silicon substrate 42 'on the absorber side.
An electrode layer 44 of palladium having a thickness of Å was deposited. An X-ray mask structure of the present invention is obtained by etching a part of the silicon substrate 42 'from the back surface and bonding the silicon substrate 42' to the reinforcing member 42.

When this X-ray mask structure abuts on the V block 46, the ground spring 45 contacts the side surface of the silicon holding frame 42 ', and photoelectrons and Auger electrons generated from the absorber 43 during X-ray exposure pass through the palladium electrode layer 44. By bringing the earth potential from the earth spring 45 to the earth, the contact between the wafer and the mask could be prevented.

Although the thickness of the thin film 44 in the above example is determined in consideration of the transmittance of X-rays and the strength of the film itself, it is substantially 0.5 μm to 5 μm.
Preferably, the thickness is μm.

Third Embodiment FIG. 5 is a plan view when an X-ray mask abuts on a V block portion in a third embodiment.

 FIG. 6 is a sectional view taken along the line AA 'of FIG.

First, when an insulator such as ceramics was used for the reinforcing member 62, an electrode 67 made of a metal such as brass, iron, or aluminum was embedded in a part of the reinforcing member 62.

In the same manner as in the second embodiment, an inorganic thin film 61 is deposited on a silicon substrate 62 'having a specific resistance of 100 Ω · cm or less, and a part of the inorganic thin film 61 is etched until the silicon substrate surface is exposed.
Nickel 68 was embedded in the portion etched by the off method. The metal to be embedded by the lift-off method may be any material as long as it has conductivity.

Thereafter, an absorber 63 and an electrode layer 64 were formed on the inorganic thin film 61 in the same manner as in Example 2, and a part of the silicon substrate 62 'was etched from the back surface to form a silicon holding frame 42', which was processed as described above. By bonding to the reinforcing member 62, the X-ray mask structure of the present invention is obtained.

In the case of this X-ray mask structure, photoelectrons and Auger electrons generated from the absorber 63 and the like are transferred from the electrode layer 64 via the lift-off metal 68 to the silicon holding frame 42 ′ and the metal of the reinforcing body.
It flows through 67 and is at ground potential at V block 66.

Also, the silicon holding frame 62 'on which the absorber pattern is formed
When bonding the reinforcing member 62 with the notch, the notch portion into which the pin 59 (FIG. 5) is fitted and the metal portion 67 of the reinforcing member 62 correspond to the portion that abuts on the V block 66 during X-ray exposure. By performing such bonding, the X-ray mask and the V block 66 can functionally obtain an electrical contact even in the automatic alignment of the automatic conveyance system.

In these embodiments, the ground contact is taken from the V block 66. However, it is also possible to pull out the ground spring from a part of the mask stage other than the V block 66, for example.

Although the present invention has been described with reference to the preferred embodiments,
The present invention is not limited to these embodiments, and other configurations are the same as those of the prior art as long as the X-ray mask structure and the gripping means are electrically connected. It is clear that the present invention includes the modified embodiment of

(Effects) As described above, according to the present invention, a conductive portion is formed on each of the X-ray mask and the means for gripping the X-ray mask, and these conductive portions are electrically connected as necessary. Since electrification at the time of exposure is prevented and photoelectrons and Auger electrons generated at the time of exposure are effectively removed, X-ray exposure with proper and excellent dimensional accuracy is realized.

[Brief description of the drawings]

FIG. 1 is a diagram schematically illustrating a cross section of an X-ray exposure apparatus according to the present invention. FIG. 2 is a diagram schematically illustrating a mask structure of the present invention. FIG. 3 is a diagram schematically illustrating a cross section taken along line AA ′ of FIG. FIG. 4 is a diagram schematically illustrating a mask structure according to another example of the present invention. FIG. 5 is a diagram schematically illustrating a mask structure according to another example of the present invention. FIG. 6 is a diagram schematically illustrating a cross section taken along line AA ′ of FIG. 1: Chamber 2: Wafer 3: Wafer chuck 4, M: X-ray mask 5: Mask check 31, 41, 61: X-ray permeable film 22, 32, 42, 52, 62: Holding frame or reinforcement 42 ', 62 ': Silicon substrate 33, 43, 63: X-ray absorber 24, 34, 44, 54, 64: Electrode layer 25, 35, 45: Earth spring 6, 26, 36, 46, 56, 66: V block 57, 67 : Metal 58, 68: Metal 29, 59: Pin

Claims (2)

(57) [Claims] 1. An X-ray exposure apparatus comprising: an X-ray generating means; a means for fixing an X-ray exposure target material at a predetermined position; and a mask holding means for fixing an X-ray mask at a predetermined position. And forming a conductive portion on each of the mask holding means,
An X-ray exposure apparatus wherein these conductive portions are electrically contacted as necessary. 2. An X-ray exposure method in which an X-ray mask is held by mask holding means and an X-ray exposure material is exposed to X-rays through the X-ray mask. An X-ray exposure method comprising forming conductive portions and electrically contacting these conductive portions as necessary.