DE2051017B2 - CRYSTAL DIFFUSION DEVICE AND METHOD FOR MANUFACTURING IT - Google Patents

Description

The invention relates to a crystal diffraction device and a method for the production thereof. In particular it is intended to manufacture a curved diffraction crystal having a crystalline diffraction element with a pair of substantially planar surfaces parallel to its atomic planes will.

Nearly perfect point focusing of X-rays could be achieved if a diffraction crystal were used which had a pair of faces parallel to its atomic planes and was ground so that one of these faces had a radius of curvature the size of the diameter D _{R of} the Rowland circle and would be toroidally curved, so that this surface would have a radius of curvature the size of the radius R _{K of} the Rowland circle in the plane of the Rowland circle and a radius of curvature of the size before D _R sin ² ß in a normal plane bisecting the Rowland circle, where Θ is the Bragg angle at which the X-rays are diffracted by the diffraction crystal from a point on the Rowland circle. A near perfect point focusing crystal monochromator could be made by using this toroidal diffraction crystal to focus X-rays from a source on the Rowland circle to a target point at a conjugate point on the Rowland circle. However, it would be very difficult to manufacture such a toroidal diffraction crystal.

A simpler type of production results if the diffraction crystal according to German Pa tenlschrift 1067 239 a concave cylinder surface is ground in. It is still known to grind the back of the crystal convex around the cylindrical front against a cylindrical *

window-like cut-out mating surface of a frame of the plated surface of the quartz substrate to press. Cylindrical cut crystals are pressed, the clad oil material over its Although relatively easy to manufacture, the melting point is sufficient, but below the damage point no higher demands on the focus for the crystalline quartz disk and the substrate ability for X-rays. 5 is heated and the molten solder material underneath

In the case of diffraction on gratings, it is known that its solidification temperature is cooled and thereby a stigmatic mapping through a spherical the quartz disk on the spherical surface curved concave grating can be approximated, soldered to the quartz substrate and a spherical See Longhurst, "Geometrical and Physical Op- curved crystalline quartz disk with a tics ”, 1960, pp. 244 to 248. io concave, spherical outer surface is formed.

The invention is based on the object of the following preferred embodiments

Crystal diffraction device for a point focus game of the invention based on the drawings To create a monochromator which purifies more easily. It shows

and is less expensive to manufacture than a toroidal fig. 1 is a logarithmic representation following

Fönniger diffraction crystal and which approximate measure of the contribution of the geometrical deviation and the intensity achievable with this when focussing to the line width reaches the intensity Ω and the resolution. sung A EIE shows, with which a spherical diffraction

Starting crystal of a crystalline diffraction, which was prepared according to the invention, theo element having a pair of substantially planar to cally X-ray radiation for various Bragg a atomic planes parallel surfaces is this 20 angle θ in the order of 50 to 90 ° task according to the invention attained in that a should focus. The intensity Ω is given in solid angle crystalline substrate with a concave, spherical no, since the intensity is formed directly proportionally shaped surface, which is the same as the fixed angle that is spanned by the spherical thermal expansion coefficient like the kri- diffraction crystal, like him has a stable diffraction element, and the crystalline X-ray source is seen, which is located at a niche diffraction element against the spherical point on the Rowland circle,
Surface of the substrate pressed and connected to it F i g. 2 an expanded, half-cut

so that a curved outer surface is produced. which corresponds to the surface of the substrate. crystal, according to the preferred embodiment

According to a preferred embodiment, 30 of the invention can be made
be provided that the crystalline substrate F i g. 3 an expanded, half-cut

consists of quartz and the radius of curvature of the tene view of the spherical diffraction crystal Substrate essentially equal to the diameter of Fig. 2,

of the Rowland district and the crystalline be- F i g. 4 a top view of the spherical diffraction

supply element in the form of a quartz disk made 35 crystal according to FIG. 3,

whose thickness is at least two orders of magnitude. Fig. 5 is a schematic representation of a point smaller than is the radius of the Rowland circle. focusing crystal monochromator that uses the

According to the invention, this object is achieved with a spherical diffraction crystal according to FIG. 2 to 4 Crystal diffraction device solved by using it.

a substrate having a curved surface defined by 40 in FIG. 1 are for different Bragg angles β in the rotation of a circle around a Rowland circle in its plane of the order of magnitude from 50 to 90 ° and the crystalline Beu- values of the intensity U and the resolution ΛEIE display element, which is placed in accordance with which, according to the contribution of the geomeder curved surface of the substrate, is curved tric deviations from the line width theoretically and connected to this and a curved 45 table can be achieved by forming a spherical outer surface of the kind that diffractive crystal for the rotation of ger X-ray focusing of a circle around a radiation in the plane of this circle from a source at a point on the axis lying. Rowland Circle to a target point at a con

Furthermore, an improved misappropriation is to be used for the youthful point on the Rowland circle position of a point-focussing diffraction crystal. It can be seen that for a given will create that in X-ray monochrome Bragg angle the intensity with increasing Aufmators can be used. solution decreases. This is done because the resolution

This is achieved, according to a preferred embodiment, by reducing the amount of the invention, by X-cutting the crystalline deviations and thus by reducing the quartz substrate, the crystalline 55 fixed angle that is Y-cut by the spherical Beu quartz disk and on a Transmission crystal is stretched as it is brought from the x-ray knife, which is seen from at least one magnitude radiation source, whereas the order smaller than the diameter of the Rowland intensity decreases by the fixed angle being the circle and the adjoining surfaces of the nert, which is spanned by the spherical diffraction quartz substrate and the quartz disk with a solder ⁶ ° crystal, as it is clad from the X-ray material, the Z-axes of the quartz radiation source is seen from. It is, therefore, the viewing substrate and the quartz within a winch that, as far as practicable, it is normally aligned which is less than the angle preferred in most applications at which the solder material is to cool from the to use the largest possible spherical diffraction crystal its solidification temperature to a lower temperature, which gives the required resolution, the breaking temperature of the quartz disk at a temperature

subsequent cooling causes the plated surface preferred embodiment of the invention the quartz disk in continuous contact with, as for a Bragg angle of 78.46 °

spherical diffraction crystal can be produced soldering material 20 to a depth of approximately, of which theoretically 18 is deposited according to the contribution of the geo 2000 angstroms on the exposed surfaces 14 and metric deviations from the line width. According to FIGS. 3 and 4, the table can be expected to press X-ray quartz disk 10 against the quartz substrate 16 according to the intensity and resolving power fo- 5, the z-axes of the quartz disk and kissed by the dashed lines in F i g. 1 of the quartz substrate are displayed so that they are aligned. Like F i g. 2, this and with the coated lower surface 14 of the spherical diffraction crystal is produced by producing a quartz disk in continuous abutment on the over-thin, Y-cut (01-0) crystalline quartz-drawn spherical surface 18 of the quartz substrate disk 10, which flat surfaces 12 and io tes is located. This can be done by having the Z axes 14, which are aligned within less than 1 angular minute of the quartz disk 10 and the quartz substrate 16 in and preferably only a few angular seconds in an evacuated space, with the upper one parallel to the atomic planes of the quartz disk Face 12 of the quartz disk are on one side. The quartz disk 10 should have a diameter of an elastic membrane and then have step- D _d , which is about an order of magnitude less than 15, a higher gas pressure is exerted on the other side of the elastic membrane than the diameter D _{R of} the Rowland circle the over- (ie, it should have a / -value of about 10, drawn surface 14 of the quartz disk is spherical where / = D _R / D _d ). It should also have a thickness t _d curve and in continuous abutment with over at least 2 orders of magnitude less than the drawn spherical surface 18 of the quartz substrate radius R _{R of} the Rowland circle. Example 20 th achieved. (A pressure of about 2.4607 kgf / cm ² , about wise can be used in the case of a Rowland circle at 35 psi, is for a quartz disk and a quartz sub a desired radius R _R of 152.4 mm (6 inches) strat with the dimensions given above is desired, a quartz disk 10 with one of these.) The spherically curved quartz disk diameter of about 25.4 mm (1 inch) and a 10 is on the coated spherical surface 18 thickness of about 0.0762 to 0.254 mm ( 0.003 to 25 of the quartz substrate 16 soldered in place, in -0.010 inch), preferably about 0.1524 mm (0.006 inch) of the quartz disk and the quartz substrate are used. The quartz disk 10 temperature above the melting point of the solder can be made by heating it from a body material 20 but below the damage to a natural or synthetic crystalline point of the quartz. For the above he-quartz bearing is cut, (whereby synthetic 30 mentioned tin-gold alloy, this tempe-quartz with Z-growth is because of its larger temperature about 400 ° C. The gas pressure is continuously uniformity is preferred) and by it is finely ground (lapped) or otherwise ground by the resilient membrane onto the surface 12, around the spherically curved quartz disk 10 to the required thickness and the required par- ture until the molten solder material 20 has sufficient allelicity between the surfaces 12 and 14 and which has had time to cool down and solidify to reach the atomic planes of the disk. gen, whereby it is the spherically curved quartz

An X-cut (10-0) crystalline quartz disk on the spot on the metallic coated one Give away substrate 16 with essentially the same thermally spherical surface 18 of quartz substrate 16 Expansion coefficients such as the crystalline binds

African Silicon wafer 10 is formed with a spherical 4 ° When the Z-axis of the spherical curved surface 18 which does not have a radius of curvature silicon wafer 10 and the quartz substrate 16, which are aligned substantially equal to the throughput, is applied to the spherical gemesser D _R of the Rowland Circle is. The quartz sub-curved quartz disc exerted a tension, strat 16 should have a diameter D _s which, if the quartz disc and the quartz substrate are larger than that of the quartz disc 10, and it 45 from the solidification temperature of the solder material should have a thickness i _s which Cool at least one size down to room temperature. This chip order is larger than that of the quartz disk. In the voltage increases with the angle of deviation of the case of a Rowland circle and a quartz disk Z-axes and with the solidification temperature of the 10 with the dimensions given above, pre-soldering material 20 and can be sufficiently large, preferably a quartz substrate 16 with a through 50 in order to break the spherically curved diffraction crystal IG knife from about 1.27 to 2.54 mm (0.050 to. For example, in the case of the above-0.100 inch) more than that of the quartz disk, a tin-gold alloy mentioned must have a spherical thickness of about 12.7 mm (Vainch) and a spherically curved quartz disc 10 and a quartz substrate-shaped surface 18 is used, which has a curvature 16 with the dimensions and the radius of about 304.8 mm (about 12 inches) given above 55 The quartz substrate 16 can also be produced half oriented by less than 30 °, in order to be able to use it from a body made of natural or lassli To prevent the quartz disk from breaking, a synthetic, crystalline quartz bearing is cut. 60 moderate avenges and atomic levels, each one having its own

The spherical surface 18 of the quartz substrate 16 have a radius of curvature that is essentially!

and the adjacent, flat surface 14 of the quartz is equal to the diameter D _{R of} the Rowland circle

Disk 10 are metallic with brazing metal For the purposes of the description and claims

tall 20, for example an alloy of 45% tin, it is assumed that the radius of curvature in the we

and 55% gold plated. This can, for example, be substantially equal to the diameter D _{R of} the Rowland

happen by the remaining avenging the circle is when it is by D _R by an amount in de

Quartz disk 10 and the quartz substrate 16 ab- order of magnitude of or less than the thickness t _d de

are covered and by deviating the hard diffraction crystal 10 under vacuum The spherical ge

eggs Rtot _BP n «^ p
Systems for studying the chem setting of a selected pattern ESCA systems of the type in which such focusing crystalline ion can be used are based on the book ESCA, published by Kai

one point

et J ~ ^ _{enstr u} ^g _ngsque ll _e ^g 22 and the specified / of _{the monochromator} is a spherical _{mi crimped} diffraction crystal 10 with the structure mgg the _{dimensions X-} ray beam

^ ^ ^ _G de 8 _{mm (0, 0} 02 inch) long _{on the} Rowland circle focus ^g. The contribution of the a _deviations to the line width of the

the

^ traniung

^ vengp
passive limit sc

Sner characteristic ^ g ^ S the spherically curved inflection

is brought where the angle O is the Bragg diffraction ^. "^ J ^ 2 d sin Θ = η A, where d the Git tenbsto J disk 10, Θ the Btaffi angle (de ^ angle the central, ^ ray of the g ^ ^ S-ray line which meets the and a tangent to the point of incidence ^ «ng supply order and λ is the WeUeda ^ ristic X-rays. ¥ w a AJ_ genstrahlenquelle 22 with e = 487 Ke £ (a and a spherical g ^ rummteri 1 ^ ^u g g 10 ^un ions having the above construction and Uimen is the Bragg angle θ78,46 for d ^ eBeu first-order (n-1) the j ^e S ™ ™ | f.

_in % £ ^! X-ray radiation focused by such a curved diffraction crystal «S, corresponds to that produced by the horizontal,

_{dotted line in Fig} . 1 is displayed. .

⁸ _M i _{e Fokuss the} approach point of the spherical overall

curved diffraction crystal 10 is a target 24

X-ray spectrometer

bra ^ _{n θεΐ} ^ _οΓ ^ _{(for example Se}

a control gap and / or a _sc photography he plate), while the X-ray source 22

contains sample to be _examined. In the case of an ESCA system according to FIG. 4, the target 24 assigns the

_{Searching sample and / or a} limitation. _{The irradiation of the sample 24 by the ^ _{arakteristische} X-ray radiation line causes _{the sample to emit} photo electrons. Em electric

_Spectrom eter, for example, as _used in the book ^ P ^^ ^ ^ _u m this

_Fotö l _e ktronenemission to analyze, and the chemischeZusammensetzungderProbe24zubestimmen.

1 sheet of drawings

S09552

rir

Claims (7)

Patent claims: 1. A method for producing a curved diffraction crystal, in which a crystalline Diffraction element with a pair of essentially flat surfaces parallel to its atomic planes is used, characterized in that that a crystalline substrate (16) with a concave spherical surface ge ίο which has the same coefficient of thermal expansion as the crystalline diffraction element has, and the crystalline diffraction element (10) against the spherical surface of the substrate is pressed and bonded to it, so that a curved outer surface is generated, which corresponds to the surface of the substrate. 2. The method according to claim 1, characterized in that the crystalline substrate from so Quartz is made and the radius of curvature of the substrate is substantially equal to the diameter of the Rowland circle and the crystalline diffraction element in the form of a quartz disk is produced whose thickness is at least two orders of magnitude smaller than the radius of the Rowland Circle is. 3. The method according to claim 2, characterized in that the crystalline quartz substrate X-cut, the crystalline quartz disk is Y-cut and cut to a diameter which is at least an order of magnitude smaller than the diameter of the Rowland circle and the adjoining surfaces (14, 18) of the quartz substrate and the quartz disk are plated with a solder, the Z-axes of the quartz substrate and the quartz disk be oriented within an angle smaller than the angle at which the Cooling the solder material from its solidification temperature to a lower temperature that Breaking of the quartz disk during subsequent cooling causes the clad surface of the quartz disk in continuous contact with the plated surface of the quartz substrate is pressed, the clad solder material above its melting point but below the damage point for the crystalline quartz disk and the substrate is heated and the melted Solder material cooled below its solidification temperature and thereby the quartz disk on soldered to the spherical surface of the quartz substrate and a spherically curved crystalline Quartz disk is formed with a concave, spherical outer surface. 4. Crystal diffraction device, characterized by the combination of a crystalline substrate (16) with a concave, spherical surface (20) and a crystalline diffraction element (10), which has substantially the same coefficient of thermal expansion as the crystalline substrate, and accordingly the concave, spherical surface of the substrate is bent and formed with it a crystalline diffraction element with a concave, spherical outer surface (12) is connected. 5. crystal diffraction device according to claim 4, characterized in that the crystalline substrate (16) consists of quartz , the radius of curvature of the spherical surface (18) of the substrate is essentially equal to the diameter of the Rowland circle, the crystalline diffraction element is a quartz disk (10) with surfaces parallel to its atomic planes ( 12, 14), which is bent in accordance with the spherical surface of the quartz substrate in such a way that the outer surface of the quartz disk has essentially the radius of curvature of the spherical surface of the quartz substrate 6. crystal diffraction device according to claim 5, characterized in that the crystalline Quartz substrate (16) is X-cut and the crystalline quartz disk (10) is Y-cut. 7. crystal diffraction device according to claim 6, characterized in that the thickness of the quartz disk is at least two orders of magnitude smaller than the radius of Rowland's circle and one Has diameter that is at least one order of magnitude smaller than the diameter of the Rowland's circle and the Z axes of the quartz substrate and quartz disk within one At an angle of less than 30 °.