JPH0833497B2 - X-ray curved crystal - Google Patents

Description

TECHNICAL FIELD The present invention relates to an X-ray curved crystal used for X-ray spectroscopy or as a focusing element in the field of X-ray spectroscopy or X-ray lithography.

(B) Prior Art The curved crystal, which has been used for many years as an X-ray spectroscopic element, has recently attracted attention as an X-ray focusing element in the field of X-ray lithography.

Conventionally, this X-ray dispersive crystal includes Si, Ge, etc., and a metal such as Al has been used for the substrate to which the crystal is attached.

By the way, when the crystal is bent and attached to the substrate,
Thin crystals are advantageous in terms of bendability. However,
The thinner the crystal, the greater the risk of the crystal breaking due to thermal changes due to the difference in expansion coefficient from the substrate. Since the coefficient of expansion of crystals such as Si and Ge and the coefficient of expansion of metals such as Al are on the order of one digit, conventional dispersive crystals had the drawback of being weak against temperature changes. Further, when a metal is used for the substrate, an ultraviolet curing adhesive cannot be used as an adhesive for sticking crystals, and it is limited to epoxy resin or the like. In this case, since the curing time was limited, the work of bending the crystal and attaching it to the substrate had to be performed within a short time of several tens of minutes to several hours. If the crystals are bent a little over a long period of time due to creep, the crystals tend to bend, but if bent with the conventional bonding time, the risk of cracking increases.

Furthermore, since the adhesive layer cannot be seen directly on the metal substrate, it is impossible in principle to monitor the adhesive layer for uniformity.

When the crystal is bonded to the substrate, the adhesive around the crystal is relatively easy to escape to the outside, but as the crystal becomes larger, the adhesive near the center of the crystal is less likely to escape to the outside. Therefore, the larger the crystal, the more uneven the adhesive layer,
This was the cause of irregularities on the crystal surface. Due to this unevenness, there may be a portion where the X-ray is not locally diffracted.

(C) Purpose The present invention has a structure in which a bonding time can be freely selected, a bonding layer can be monitored when a crystal is curved and bonded to a substrate, and the bonding layer does not have unevenness. It is to provide an X-ray curved crystal that is resistant to subsequent temperature changes.

(D) Structure Use a material such as glass that has a coefficient of expansion less than twice that of the crystal and that transmits ultraviolet and visible light for the support substrate to which the crystal is attached, and allow extra adhesive to escape to the crystal attachment surface of the substrate. Make one or more grooves or make an appropriate number of holes. In this case, the diameter of the hole should be as small as possible, the width of the groove should be as narrow as possible, and the total area of the hole or groove should be less than one-third of that of the bonding surface in order to smoothly align the crystal with the substrate bonding surface. desirable.

(E) Example An X-ray curved crystal of the present invention is shown in FIG. The supporting substrate 1 has a coefficient of expansion not more than twice the coefficient of expansion of the crystal 3, and is made of a material such as glass which is transparent to visible light and ultraviolet rays having a wavelength of around 365 nm. As a result, the ultraviolet curable adhesive 2 can be used as the adhesive, and the adhesive can be cured by irradiating the back surface of the substrate 1 with ultraviolet rays to cure the adhesive. Also, the adhesive layer can be monitored from the back surface of the substrate 1. Further, as shown in FIG. 2, a large number of grooves (FIG. 2 (a)) or a large number of holes (FIG. 2 (b)) are formed on the bonding surface of the crystal 3. By this,
In the pasting work, the escape of the adhesive can be secured and the adhesive layer can be made uniform.

The manufacturing method of such a crystal will be described below. First
In the figure, first, the ultraviolet curable adhesive 2 is uniformly applied to the bonding surface of the substrate 1 described in FIG. 2 (b).

Next, the crystal 3 to be pasted is placed on the pasting surface, and the pressing plate 4 is used from above to gradually bend it in a thermostatic chamber so as to align it with the pasting surface. When the bending time is long, the creep becomes large and the crystal is easy to bend without cracking (c).

It is confirmed from the back surface of the substrate 1 that the crystal 3 is completely bent along the attachment surface, and the substrate 1 and the holding plate 4 are adjusted while observing the interference fringes of the crystal so that the adhesive layer has a uniform thickness. After the adjustment, the back surface of the substrate 1 is uniformly irradiated with ultraviolet rays 5 to cure the adhesive 2 (d).

Finally, the holding plate 4 is removed, and the surface of the crystal 3 is washed with dilute acid to complete the production of the X-ray curved crystal (a).

 Next, specific examples of crystals will be shown.

An example is the case where Ge (111) with a size of 70 × 80 (mm) and a thickness of 0.3 mm is used as a crystal.

Since the expansion coefficient of Ge is 6.0 × 10 ^-6 ° C ^-1 at room temperature, La that has the same expansion coefficient at room temperature as the material of the substrate 1 to be attached.
SF ₀₆ and LaSF ₀₁₉ (optical glass manufactured by Ohara Optical Co., Ltd.) are used (By the way, the expansion coefficient of the Al substrate is 23 × 10 at room temperature.
^-6 ° C ^-1 ). In particular, LaSF ₀₆ has a relatively high transmittance for ultraviolet rays of 38% for light of 360 nm wavelength and 62% for light of 370 nm wavelength per 10 mm thickness. Optical glass was selected as the substrate material because it is preferable to general glass because the thickness of the adhesive layer is monitored with visible light and uniformity of glass quality is required during ultraviolet irradiation. In addition, there is a wide range of expansion coefficients for optical glass.

0.5mm on the bonding surface of the crystal 3 (substrate 1), 0.5mm depth
Cut multiple grooves at intervals of 2 mm to allow the adhesive 2 to escape.

An ultraviolet curing adhesive is evenly applied to the substrate 1, the crystal is fixed thereon, and the crystal is gradually bent by the holding plate 5. When it is confirmed that the crystals are on the attachment surface, adjust the adhesive layer so that it is uniform, and irradiate the mercury lamp uniformly from the back surface to cure the adhesive. Finally, the holding plate 5 is removed, and the surface of the crystal 3 is washed with a dilute solution of hydrofluoric acid and nitric acid.

(F) Effect The following points have been improved over the conventional X-ray curved crystal using a metal substrate.

First, since the expansion coefficient of the substrate is close to that of the attached crystal, the manufactured X-ray curved crystal is less likely to be cracked by the temperature change than the conventional X-ray dispersive crystal. The crystal used for that purpose can be made thinner than before, and as a result, when bending the crystal, it becomes easier to bend and the risk of cracking is reduced.

Next, since it became possible to attach with an ultraviolet curing adhesive, the time required to bend the crystal could be set arbitrarily, and if the crystal was gradually bent over a long period of time, creep could be expected, and that amount of crystal could be expected. It is hard to break and easy to bend.

A substrate that transmits visible light is useful for monitoring the curved state of the crystal and the adhesive layer, and a large number of holes and grooves on the attachment surface of the substrate help escape excess adhesive and help to make the adhesive layer uniform. As a result, the problem of unevenness of the crystal surface due to local nonuniformity of the adhesive layer was eliminated, and uniform X-ray focusing became possible.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an X-ray curved crystal of the present invention and a process for manufacturing the same, and FIG. 2 is a schematic diagram of a crystal substrate, in which a large number of grooves are cut in a gluing surface as an escape of an adhesive (a). ，
The case where a large number of holes are formed is shown in FIG. 1 ... Support substrate, 2 ... UV curable adhesive, 3 ... Crystal, 4 ...
… Presser plate, 5… UV

Claims (1)

[Claims] 1. An X-ray crystal obtained by sticking a crystal along a curved surface of a supporting substrate, wherein the supporting substrate has a coefficient of expansion not more than twice the coefficient of expansion of the crystal and is transparent to visible light and ultraviolet rays. An X-ray curved crystal, which is formed by the method described above and is provided with one or more grooves or an appropriate number of holes for allowing the adhesive to escape on the crystal sticking surface of the supporting substrate.