JP5594723B2 - X-ray target and method for producing X-ray target - Google Patents

Description

  The present invention relates to a fine X-ray target that satisfies the high resolution and high contrast image required in the fields of medical, biochemistry, protein structure analysis, fluorescent X-ray analysis and the like using X-rays, and a method for producing the same. .

  Observation, analysis, processing, etc. in microscopic areas such as nanoscience and nanotechnology are actively performed. For example, the minimum processing of semiconductor integrated circuits is required to increase the speed, performance, and functionality of electronic information communication equipment. The dimensions have entered the nanometer level and are continuing to become finer. Failure analysis of miniaturized transistors and multilayer wiring connecting them is becoming increasingly difficult, and high resolution of observation and analysis equipment is required.

  As a technique for improving the performance of a semiconductor integrated circuit without depending on miniaturization, there is a three-dimensional mounting in which a plurality of semiconductor chips are stacked and integrated in the vertical direction. Here, semiconductor chip / wafer is drilled with high aspect ratio to form a through electrode that fills the conductor, and bumps are formed on the front and back surfaces of the chip / wafer to connect the upper and lower chips / wafer together. As a result of this technique, the number of connecting terminals between chips / wafers in the vertical direction is increased, and an inspection technique different from conventional defect analysis techniques is required.

  Until now, in the analysis of semiconductor chip multilayer wiring and bump connections, cross-section observation by sampling inspection has been the mainstream, but it has become difficult to polish and expose the cross-section with high precision due to miniaturization. Yes. In addition, it is expected to develop a cross-sectional observation technique using a focused ion beam (FIB) apparatus, but at present, it takes several hours or more to expose a cross section of a large area of several tens to hundreds of micrometers. It takes a lot of time. As described above, an inspection technique that breaks and observes a sample by processing such as exposing a cross section of one cross section of the sample has a very low throughput, and cannot be fed back quickly to a semiconductor manufacturing process. In addition, non-destructive inspection using an ultrasonic microscope has a resolution as high as several micrometers, and it is difficult to determine whether or not a defect is possible by clearly observing connection parts such as LSI multilayer wiring and three-dimensional mounting through electrodes. It is.

  From such a technical background, an X-ray nondestructive inspection technique for obtaining a projection image by X-ray transmission absorption of a sample by irradiating the sample with X-rays and detecting the transmitted X-ray is put at a glance. In the conventional X-ray non-destructive inspection apparatus, an X-ray tube that generates an X-ray by causing an accelerated electron beam to collide with a metal is often used as an X-ray generation source. In general, in an X-ray generator, a metal that collides with accelerated electrons is called a target. The distance from the target until the sample is irradiated with the X-ray generated in a cone beam shape depends on the distance from the target to the imaging surface that obtains the X-ray transmission absorption image of the sample. The geometric magnification of the X-ray transmission absorption image is determined. Increasing the geometric magnification can be achieved by increasing the distance ratio between the sample and the target, or moving the imaging surface away from the target, but the target size is projected on the imaging surface accordingly. Then, it appears noticeably blurred and the resolution is lowered. Since the size of the target greatly affects the resolution, it is necessary to realize a point light source by reducing the size of the target in order to obtain a high-resolution and high-resolution X-ray transmission / absorption image. The X-ray generation source of the current X-ray non-destructive inspection system is a sub-micrometer that can be used as a point light source with a resolution of sub-micrometer level by colliding an accelerated electron beam with an electron lens down to the sub-micrometer level. A focus X-ray source is realized. In addition, X-rays that pass through the sample can be collected by a diffraction grating called Fresnel zone plate and imaged to obtain a high-resolution X-ray transmission absorption image of several tens to hundreds of nanometers. There is microscope technology.

  As an evaluation index for an X-ray transmission absorption image, not only resolution but also contrast is important. Although the resolution is improved by the technology of the microfocus X-ray source, in order to obtain a high-contrast image, it is necessary to reduce the X-ray dose generated from the beryllium etc. supporting the target rather than the X-ray dose generated from the metal target. There is. The target is a small point, and it is ideal that the target does not move by floating alone in a hollow space. However, in reality, a substrate for fixing and supporting a metal target to the outside is required. X-rays are generated not only from a metal target but also from a support substrate. The X-ray generated from the support substrate reduces the contrast as well as the resolution. In order to suppress the X-ray dose generated from the support substrate, it is generated from the target by using a material composed of an element with a small atomic number and reducing the volume (= area x thickness) that the electron beam collides with. It is necessary to reduce the X-ray dose generated from the target support with respect to the X-ray dose. That is, in order to obtain a high-contrast X-ray transmission / absorption image, the ratio between the X-ray dose generated from the target and the X-ray dose generated from the target support may be increased. Here, this X-ray dose ratio is called the X-ray intensity ratio. In order to obtain a high-resolution X-ray transmission absorption image, it is necessary to make the target finer, but if the target support is not made finer, the X-ray intensity ratio decreases accordingly, making it difficult to obtain a high-contrast image. It becomes.

  Thus, an X-ray target is required to achieve both high resolution and high contrast X-ray transmission absorption images in X-ray nondestructive inspection. The challenge is how to refine the target support while ensuring the mechanical strength together with the target without reducing the X-ray intensity ratio. Furthermore, it is difficult to handle a target support having a low mechanical strength and a thin film and to attach it to a frame for installation in the apparatus with good reproducibility. In general, beryllium Be and carbon C, which generate less X-rays, are used for the target support. However, Be is highly toxic to the human body and requires special processing and processing equipment, which makes it flexible. There are concerns about safety, etc. In addition, the C film has many problems such as that fine processing by a wet / dry process is not easy as compared with general SI.

  Furthermore, X-ray nondestructive inspection has the following problems as well as targets. In a general X-ray generator, the energy of the generated X-ray is about several to several tens of keV, and it is not high brightness. Therefore, in order to obtain a clear X-ray transmission absorption image with high contrast, the thickness of the sample There is a limit. As a non-destructive inspection, it is desirable that the sample can be observed as it is without limiting the sample as much as possible. Large-scale synchrotron radiation equipment can generate high-intensity X-rays, but how to achieve a general industrial-level X-ray non-destructive inspection system is a challenge.

  In “Mirakuru”, which is an X-ray generator using bremsstrahlung in which a fine target is placed on the electron orbit of the synchrotron (see Non-Patent Document 1), the generated X-ray energy is high and the brightness is high. Therefore, there is a possibility that a high-resolution X-ray transmission / absorption image can be obtained even with a sample having a thickness as large as a millimeter order. In addition, normal phase contrast images are taken at a distance of about 1 m or more between the sample and the image sensor. In this Miracle method, the phase contrast is also used in contact and proximity optical systems where the sample and image sensor are in close contact. The feature is that the edges appear to be emphasized in the image, and a new X-ray imaging image can be provided.

JP2001-216927 JP2008-334699 Y. Yamada, “Generation and Use of High-Quality X-rays Using the Desktop Synchrotron“ Mirakuru 6X ”,” Applied Physics, Vol. 74, No. 4, 2005, pp. 462-471. HIronarI Yamada, "Super Photon Generator CollIsIons of CIrculatIng RelatIvIstIc Electrons and WIre Targets," Jpn. J. Appl. Phys., Vol. 35, pp. L182-L185, 1996.

  An object of the present invention is to provide an X-ray target necessary for obtaining a high-resolution and high-contrast X-ray transmission / absorption image, for example, in an X-ray nondestructive inspection, and a manufacturing method thereof.

  In order to solve the above problems, the present invention provides an X-ray target including an Au target formed on a polyimide film. This X-ray target is, for example, that the polyimide film is formed on a substrate, a hydrophilic treatment is applied on the substrate, and the polyimide is used as a target mounting frame for an apparatus using the X-ray target. A membrane is attached.

  The present invention also provides an X-ray target comprising a W target formed on a C fiber. This X-ray target is, for example, that the W target is columnar, rod-shaped, or wire-shaped, the rod-shaped or wire-shaped W target is cross-linked on a plurality of C fibers, The C fiber is attached to a target attachment frame to a device using the above-mentioned.

  The present invention also provides an X-ray target manufacturing method in which an Au target is formed on a polyimide film. This method includes, for example, coating the polyimide film on a substrate, peeling the polyimide film coated on the substrate in a liquid, performing a hydrophilic treatment on the substrate, and an X-ray target. It is provided that the polyimide film in the liquid is scooped off by a target mounting frame to a device utilizing the above.

  The present invention also provides an X-ray target manufacturing method in which a W target is formed on a C fiber. This method includes depositing the columnar W target on the C fiber, bridging the rod-shaped or wire-shaped W target on a plurality of the C fibers, and an apparatus using an X-ray target. The C fiber is attached to a target attachment frame.

  According to the present invention having the above features, an X-ray target for achieving both high resolution and high contrast images can be realized at low cost.

  In this specification, the X-ray intensity ratio is 100 or more, that is, the fine target condition for suppressing the X-ray dose generated from the target support to 1/100 or less of the X-ray dose generated from the target is calculated. The design is also explained. Since the micro target needs to be connected to a frame or the like for installation and fixing in the apparatus, a micro processing and mounting method for continuously connecting micro target of micrometer level to a frame of millimeter size explain. The produced fine target is uncooled and produced at low cost.

The figure which showed one Embodiment of this invention. The figure which showed one Embodiment of this invention. The figure which showed one Embodiment of this invention. The figure which showed an example of the X-ray intensity ratio in the X-ray target by one Embodiment shown in FIG. 1 of this invention. The figure which showed one Embodiment of this invention. The figure which showed an example of the X-ray intensity ratio in the X-ray target by one Embodiment shown in FIG. 5 of this invention. The figure which showed the design figure (upper) of the polyimide Au target in one Example of this invention, and the X-ray intensity ratio calculation example (lower) of a polyimide Au target. The figure explaining the preparation procedure of the polyimide thin film support Au target in one Example of this invention. In one embodiment of the present invention, the hydrophilic treatment apparatus (samco FA-1S) (FIG. 9a), the hydrophilic treatment conditions (FIG. 9b), and pure water was dropped onto the SI chip that had been subjected to the hydrophilic treatment in this setting. The figure which showed the comparison result (FIG. 9c). The figure which showed the spin coater (FIG. 10a) in one Example of this invention, the graph (FIG. 10b) of the rotation speed and film thickness, and the setting (FIG. 10c) of the apparatus at the time of 100 nm thin film film-forming. As a result of conducting a verification experiment (FIG. 11a) and whether or not the polyimide can be peeled off from the substrate by changing the pre-baking temperature and its time after film formation of the polyimide in one embodiment of the present invention (FIG. 11b, c) ). The figure which showed the resist material at the time of spin-coating the resist for UV lithography to the prebaked polyimide thin film in one Example of this invention, a spin coater setting, prebaking conditions, and a resist film thickness. The figure which showed the line drawing apparatus in one Example of this invention. The figure which showed the setting of the line drawing apparatus in one Example of FIG. FIGS. 15A and 15B show development conditions for samples exposed under the same conditions in the example of FIG. The figure which showed the line pattern produced in one Example of FIG. The figure for demonstrating attachment of the SI chip at the time of the vacuum evaporation in one Example of this invention. The figure which showed the result of having immersed in the various liquid in one Example of this invention, and observing the change of a polyimide. The figure which showed the Au line observed after lift-off Au with ethanol in one Example of FIG. The figure for demonstrating removal of the excess polyimide in one Example of this invention. The figure for demonstrating the case where a polyimide is peeled with the buoyancy of the polyimide in one Example of this invention, and the tension | tensile_strength of water. The figure for demonstrating the cut of the extra polyimide in one Example of FIG. The figure which showed the polyimide Au target baked and solidified after the flame | frame attachment in one Example of FIG. The figure which showed the target frame for FIB used for preparation of the C fiber support body W pillar target in one Example of this invention. The figure which put together the X-ray-intensity ratio at the time of the dimension of W pillar and C fiber which achieves the intensity ratio 100 in one Example of FIG. 24, and the dimension. The figure which showed the W target on C fiber in one Example of this invention. The figure which showed the W target on C fiber in another one Example of this invention. The figure explaining refinement | miniaturization of C fiber in one Example of this invention. The figure explaining refinement | miniaturization of C fiber in another one Example of this invention. The figure which showed typically the FIB fixed C fiber support body W wire target in one Example of this invention. The figure explaining fixation of the target at the time of FIB apparatus insertion in one Example of this invention. The figure which showed the node of the W wire produced with the Ga ion beam of FIB in one Example of this invention. The figure which showed the W wire target cut | disconnected with the Ga ion beam of FIB in one Example of this invention. The figure which showed the W wire target and support body which were fixed by W film-forming in one Example of this invention. The figure which showed the target completed by the redeposition adhesion | attachment of the silver paste and W in one Example of this invention.

1. Formation of Au target using polyimide thin film as a support FIG. 1 shows an example of a gold Au thin film target 3 formed on an extremely thin polyimide film 2. The polyimide film 2 is mechanically high in strength (equivalent to steel) and close in composition to the light element material carbon C, and is therefore suitable as a target support material. The polyimide film 2 can be spin-coated to form a 100 nm-class ultra-thin film, and a fine target 3 such as Au is formed on the polyimide film 2 by a lithography process. If hydrophilic treatment is performed on a substrate such as SI or glass before spin coating the polyimide film 2, the polyimide film 2 can be easily peeled off from the glass substrate in liquid (Patent Document 2). reference).

Since the polyimide film 2 has high mechanical strength, it is difficult to expand and contract even on the surface in an aqueous solution and can float while maintaining its shape to some extent. Therefore, by skimming the polyimide film 2 directly at the frame 1 for mounting the motor Getto 3 in devices utilizing X-ray target, such as X-ray microscope and X-ray non-destructive inspection apparatus, difficult handling of ultra-thin The process becomes easy. Further, since the polyimide film 2 is wound around the frame 1 in a self-organizing manner, no extra adhesive or the like for fixing is required. The frame 1 can be in the form of, for example, two parallel metal rods of millimeter level.

  In this way, a semiconductor microfabrication process using the features of the polyimide film 2, that is, formation of a uniform 100 nm-class ultrathin polyimide film 2 without unevenness, and fineness to obtain a high resolution / high intensity ratio by the lithography process. High-resolution and high-contrast X is achieved by forming the target 3 shape, handling technology for peeling the polyimide film 2 from the substrate and attaching it to the frame 1, and processing technology for removing unnecessary portions of the polyimide support by laser or etching. An X-ray target capable of acquiring a line transmission absorption image is produced. According to the Au target forming method using the polyimide thin film as a support as described above, since it is a conventional semiconductor process in units of wafers, it can be manufactured at low cost.

2. Direct local deposition of W on C fiber by FIB FIG. 2 shows a target 5 having a columnar structure in which tungsten W is locally deposited on carbon C fiber 4 cross-linked to frame 1. In this technique, a focused ion beam (FIB) processing device is used to directly deposit a metal such as W on a minute local region on the C fiber 4 to form an X-ray target.

C fibers 4 having a diameter of a micrometer level are attached to the two parallel frames 1 in advance. When this is introduced into the FIB apparatus and tungsten carbonyl W (CO) ₆ is used as an irradiation gas and a Ga ⁺ ion beam is irradiated to a local region on the C fiber 4, W is deposited on the surface of the C fiber 4. . By continuously depositing W, the columnar W target 5 can be formed on the C fiber 4.

In order to increase the X-ray intensity ratio, an extra C fiber 4 may be irradiated with a Ga ⁺ ion beam and etched.

3. Connection of W rod on C fiber by FIB FIG. 3 shows a target 6 in which a W rod is bridged on two C fibers 4 bridged on a frame 1. Two C fibers 4 having a diameter of a micrometer level are attached to two parallel frames 1 in advance. Next, two thin wires (not shown) such as Al are attached to the frame 1 in the same manner in parallel with the two C fibers 4. Thereafter, the target W wire 6 is placed orthogonally to the C fiber 4 and the Al wire, and the two points in contact with the Al wire are temporarily fixed with a conductive Ag paste or the like and crosslinked. The work so far is a processing level that can be handled manually on a stereomicroscope.

This sample is introduced into the FIB apparatus. First, two points where the C fiber 4 as a support and the W wire 6 are orthogonally contacted are bonded and fixed by FIB processing. There are two fixing methods. First, by using W (CO) ₆ gas, Ga ⁺ ion beam is irradiated near the contact point between C fiber 4 and W wire 6, and W is deposited between C fiber 4 and W wire 6. It is a method of fixing. The second is the phenomenon that W and C etched and released again adhere to the surface of the etching process by irradiating the Ga ⁺ ion beam to the perpendicular point of C fiber 4 and W fiber 6 and etching. This is a method of fixing the C fiber 4 and the W fiber 6 by this reattachment film. It is also possible to fix these two methods together.

  Thereafter, in order to eliminate the extra W wire 6, two portions of the W wire 6 are cut by FIB and separated. At this time, it is necessary to devise so that stress is generated in the W wire 6 and the two points of the fixed W wire 6 and the C fiber 4 are not separated. Rather than cutting the W wire 6 at one point at a stretch, the stress is dispersed by cutting several points to the middle of the W wire 6 so that the stress is not concentrated on the fixing points of the C wire 4 and the W wire 6. Finally, the Al wire is removed from the frame 3 together with the excess W wire 6 with tweezers.

4). Calculation of X-ray intensity ratio In order to execute each of the manufacturing methods described above, an X-ray intensity ratio is calculated so as to design in advance an X-ray target that can achieve high resolution and high contrast. Here, the X-ray generation method is an “X-ray generator” that generates X-rays by bremsstrahlung by a method of setting a fine target on the electron orbit of the synchrotron. The photon amount N _Br generated by the Miracle method is given by Equation (1) (see Non-Patent Document 2).

Where, I: accumulated current value, α _t : X-ray target cross section, S _b : electron beam cross section, n _t : X-ray target density, χ _t : X-ray target thickness, dα _Br : braking The differential cross section of radiation.
Since the X-ray intensity ratio is a ratio between the photon amount N _Brt generated from the target and the photon amount N _Brs generated from the target support, the following equation (2) is obtained when the X-ray intensity ratio is R.

Here, subscripts t and s indicate a target and a target support, respectively. Further, V _t is the volume of the target irradiated with the electron beam (= α _t χ _t ), and V _s is the volume of the target support irradiated with the electron beam (= α _s χ _s ).
As can be seen from the equation (2), the X-ray intensity ratio R is the differential cross-sectional area ratio _{dα Brt} / _{dα Brs} between the target and the target support, the density ratio n _t / n _s , and the region where the electron beam is irradiated and passes. It is determined from the volume V _{t /} V _s. In other words, the differential cross section ratio _{dα Brt} / _{dα Brs} and the density ratio n _t / n _s are determined by the constants of the material itself constituting the X-ray target, and the volume ratio V _{t /} V _s is free from the fabrication process. Can be determined.
The total radiation cross section α _Br is given by the following equation (3).
_{dα Brt} / _{dα Brs} is obtained.

Here, Z: atomic number, r _e: is an electron orbit radius. That is, the differential cross-sectional area ratio _{dα Brt} / _{dα Brs} is determined only by the atomic number Z as shown in the following formula (4).

In the following, the X-ray intensity ratio R of the X-ray target formed by each of the above-described methods is calculated from the equation (2).

4-1. X-ray intensity ratio R in the case of Au target formation using polyimide thin film as a support
The X-ray intensity ratio R is calculated in the structure shown in FIG. The metal material of the target 3 is Au (Z = 79, n _t = 19.3 g / cm 3), and the target support 2 is made of polyimide (PI). When it is approximated that most of the atoms constituting the PI film are C (Z = 6, n _s = 1.7 g / cm3), the X-ray intensity ratio R is expressed by the following equation (5).

From this, the condition that the X-ray intensity ratio R is 100 or more is obtained.

Thus, if the volume V _{t of the} target 3 is 6.2% or more with respect to the volume V _s of the target support 2 through which the electron beam passes, the condition that the X-ray intensity ratio R is 100 or more can be achieved.

However, since the manufacturing process problem and the diameter of the focused electron beam are determined by the performance of the apparatus, the dimensions of the target 3 that can achieve the condition that the X-ray intensity ratio R is 100 or more are limited. The diameter of the electron beam irradiated to the target 3 is 5 mm. As a limitation on the manufacturing process and structure, if l _t = 0.5 mm and h _s = 100 nm, X-rays for each target size W _t (= ht) A graph of the intensity ratio R is shown in FIG. In the 10 μm target 3, the condition that l _s = 1.5 mm or more and the X-ray intensity ratio R is 100 or more can be achieved, but in the 1 μm target 3, the condition cannot be achieved even if l _s = 0.5 mm. In order to satisfy a sufficient X-ray intensity ratio R even with a fine target 3 of 1 μm, an extra PI film must be further eliminated.

FIG. 5 shows a structure in which an extra PI film is removed by dry etching or the like. Similarly, when the change in the X-ray intensity ratio R with respect to W _s is calculated for the target 3 having a size of 1 μm, the result is as shown in FIG. When the target size becomes 1 μm and the target size becomes fine, the effect of the X-ray target support 2 becomes prominent, and the X-ray intensity ratio R reaches 100 or more unless W _s is 10 or less and l _s is 7.5 or less. I can't do it. The X-ray target 3 using the PI film as the target support 2 needs to be designed in consideration of the above.

4-2. X-ray intensity ratio in the case of W local direct deposition on C fiber by FIB Calculate the X-ray intensity ratio in the structure shown in FIG. When the metal material of the target 5 is W (Z = 74, n _t = 19.1 g / cm ³ ) and carbon C (Z = 6, n _s = 1.7 g / cm ³ ) is used for the target support 4, X The line intensity ratio R is expressed by the following formula (7).

From this, the condition that the X-ray intensity ratio R is 100 or more is obtained.

Next, the volume V _t if 7.2% or more X-ray intensity ratio R of the target 5 with respect to the volume V _s of the target support 4 which the electron beam passes through can be achieved the condition of 100 or more. The diameter of the electron beam applied to the X-ray target 5 is 5 mm, and the condition that the diameter d _{t of the} target 5 cannot be larger than the diameter d _s of the target support 4 is added in consideration of the processing method by FIB. When forming the W Columns FIB, X-ray intensity ratio R when d _t = d _s of the diameter d _t of consideration of the target 5 with respect to the diameter d _t matches the diameter d _s of the target support 4 Target 5 In order to achieve the condition that the X-ray intensity ratio R is 100 or more from now on, it is necessary to form a W pillar height ht of 358 μm or more as the target 5.

4-3. X-ray intensity ratio in the case of W rod connection on C fiber by FIB With regard to “Local local deposition of W on C fiber by FIB” described above, the volume of target 5 is increased due to the performance of FIB processing. The X-ray intensity ratio R cannot be increased too much. Therefore, a larger X-ray intensity ratio R can be obtained by connecting the W rod 6 to the two C fibers 4 as shown in FIG. Using the equation (6), the diameter of the electron beam irradiated to the X-ray target is 5 mm, and when a W rod 6 having a diameter of 1 μm and a length of 0.5 mm is connected to the C fiber 4 for a 1 μm target, In order to achieve the intensity ratio, the diameter d _s of the C fiber 4 must be 0.84 μm or less. Similarly, when the case of φ10 μm is calculated for a 10 μm target, the diameter d _s of the C fiber 4 is 8.4 μm or less, and it is necessary to bridge the micrometer level C fiber 4 to the frame 1.

  In order to further reduce the volume of the target support 4 and increase the X-ray intensity ratio R, the W rod 6 can be microsampled and connected to the C fiber 4 to form the structure of FIG. It is desirable to adopt this method in order to fix the W rod 6 stably with high adhesion strength between the W rod 6 and the C fiber 4.

1. Formation of Au target using polyimide thin film as a support Here, we will explain the setup and considerations of the equipment in the target production experiment conducted based on the design that satisfies the X-ray intensity ratio of 100 or more, along with the target production procedure. To do.

  1-1. Design of a polyimide Au target An Au line is formed on a polyimide thin film support by a photolithographic technique and is manufactured by a process of attaching to a target. Calculate the X-ray intensity ratio = 141 per unit volume of Au and polyimide (assuming ≈C) from the equations (1) and (2), and design the target. FIG. 7 shows a summary of the dimensions of Au and polyimide that achieve an intensity ratio of 100 and the X-ray intensity ratio at that dimension.

  1-2. The preparation procedure of the polyimide thin film support Au target is shown in FIG. In this experiment, a target of 10 μm is manufactured simultaneously with Au 1 μm, and the settings and conditions of various devices in each item will be described according to the manufacturing procedure.

<Preparation of PI solution>
Dilute the polyimide varnish Q-VR-X0719 to 1/4 by the following weight ratio.
Polyimide varnish Q-VR-X0719: 5
Bis [2- (2-methoxyethoxy) ethyl] ether: 6
Methyl benzoate: 9
(Weight ratio)

<Hydrophilic treatment of SI substrate (samco FA-1S)>
SI chips diced to 15mm x 15mm can be easily peeled off by applying hydrophilic treatment with compact RIE before spin coating polyimide. Fig. 9a-c shows the results of comparing hydrophilicity by adding pure water to the SI chip that had been subjected to hydrophilic treatment (samco FA-1S), the hydrophilic treatment conditions, and the SI chip that had been subjected to hydrophilic treatment under the above settings. Shown in

<Polyimide 100nm film formation>
The polyimide thin film is produced by spin coating. The spin coater used, and its rotation speed and film thickness graph are shown in FIGS. 10a-b. From the graph, polyimide was deposited at a setting of 7000 [rpm] for the production of a polyimide thin film having a thickness of 100 nm. FIG. 10c shows the apparatus settings for forming a 100 nm thin film.

<Polyimide pre-bake time and temperature peeling success / failure>
Polyimide do peeling can verification experiment from board by a change in the film formation after the prebake temperature and the time, the results are summarized in FIG. 11 (a). Further, FIG. 11B shows a polyimide manufactured under the conditions. The success or failure of peeling can be seen by looking at the surface of the polyimide after pre-baking. FIG. 11 (c). From this result, the subsequent experiments were conducted at a pre-baking temperature of 70 ° C./5 mIn.

  A pre-baked polyimide thin film is spin-coated with a resist for UV lithography. FIG. 12 shows resist materials for 1 μm and 10 μm lines, spin coater settings and prebake conditions, and the film thickness of the resist formed based on these conditions.

<Au line pattern drawing>
After applying the resist, Au lines of 1 μm and 10 μm (both line lengths of 500 μm) are drawn. The settings of the drawing device (Nikon Projection Aligner PrAII-SS (Fig. 13))
Shown in The development conditions for the samples exposed under the same conditions are summarized in FIGS.

  From this result, 1 μm development is performed with 3 mIn stirring, 10 μm exposure with 400 mJ, and then 5 mIn static development. The line pattern produced by this method is shown in FIG.

  After developing both 1μm and 10μm, insert TI / 20nm first in order of Au and then deposit it in order to improve adhesion with polyimide. For 1μm, Au is deposited to 1μm. For 10μm, about 200nm of Au is deposited, and then deposited to 10μm by gas deposition.

  In addition, when the sample is inserted into the vapor deposition apparatus, there is a possibility that the polyimide cannot be peeled off from the substrate unless the following is taken into consideration.

 Mask the four corners of the I Al foil except the exposed chip lines and alignment marks.

II Attach heat so that the heat can be dissipated in Al night in order to secure adhesion to the water-cooled part of the vapor deposition system.
As shown in FIG. 17, the heat treatment is performed so that heat is not accumulated in the SI chip as shown in FIG.

<Au lift-off>
The lift-off of Au is performed with ethanol, which causes little damage to the polyimide.
A polyimide film formed on an SI substrate (100 nm film thickness) coated with resist AZP4903 (film thickness 1 μm) was immersed in ethanol, acetone and NMP for 15 minutes, and changes in the polyimide were observed. The results are shown in FIG. 18 (from the left, polyimide, ethanol, acetone, NMP before resist application).

  FIG. 19 shows 1 μm and 10 μm Au lines observed after lift-off of Au with ethanol.

<Cutting excess polyimide>
After forming an Au line to reduce the generation of X-rays from the support, excess polyimide is removed by dry etching into a shape as shown in FIG.

  Like the Au line formation, the pattern of the part to be cut by UV exposure was drawn and dry etching was performed to remove excess polyimide. The settings and conditions of each device in this process are as follows.

・ Resist spin coating Spin coating of resist AZP4903 at 3500rpm / 30sec (film thickness: 10μm)
・ Resist prebake 80 ℃ / 5mIn
・ UV exposure (projection aligner PrAII-SS)
Alignment required Exposure: 1000mJ / cm2
・ Development (AZ400K: pure water = 1: 4)
Stir development: RT / 5mIn
Pure water rinse: 1mIn or more ・ Polyimide-dry etching Compact RIE input gas O2
Gas flow rate 20sccm
Input power 20W
Time 3mIn

<Polyimide peeling and attachment to the frame>
The polyimide is removed in pure water at 70 ° C. Gradually soak in pure water from the corner of the chip and peel with polyimide buoyancy and water tension. (Fig. 21)

  Then, as shown in the figure below, excess polyimide is cut with scissors as shown in FIG. 22 and scooped up with a frame.

  The soaked polyimide is naturally dried for 10 mIn or more and then baked in an oven in the order of 220 ° C./15 mIn 280 ° C./30 mIn to completely solidify. (Fig. 23)

2. Here, we will explain the experimental results of fine target fabrication using FIB microfabrication equipment. As with the polyimide support Au target described above, a C fiber support W column target fabrication experiment was conducted based on a design drawing of a target having a structure that achieves an X-ray intensity ratio of 100.

2-1. C Fiber support W Target
The C fiber support W pillar target is produced by a process of forming a high aspect W pillar on the C fiber (7 μmφ) fixed to the FIB frame (Fig. 24) by W film formation of the FIB device. The X-ray intensity ratio per unit volume of W and C = 124 is calculated from the equations (1) and (2), and the target is designed. FIG. 25 shows a summary of the dimensions of the W column and C fiber that achieve an intensity ratio of 100 and the X-ray intensity ratio at that dimension.

2-2. C Deposit of W by FIB on fiber
The W target deposit experiment on C fiber attached to the FIB frame was conducted. Experimental conditions and experimental results are shown in FIGS.

<Experimental conditions for FIG. 26>
Focused ion beam processing and observation device FIB: Hitachi High-Technologies FB-2100
Ga + ion beam acceleration voltage Vacc = 40 kV
Aperture size: 5 μm
Irradiation gas: W (CO) 6 Tungsten hexacarbonyl Deposition time: 5 minutes

<Experimental conditions for FIG. 27>
Focused ion beam processing and observation device FIB: Hitachi High-Technologies FB-2100
Ga + ion beam acceleration voltage Vacc = 40 kV
Aperture size: 5 μm
Irradiation gas: W (CO) 6 Tungsten hexacarbonyl Deposition time: 5 minutes

2-3. Refinement of C fiber C fiber support W column target is required to form W column on C fiber and at the same time make C fiber (φ7μm) itself thin to about φ1μm. Here, the experiment of the refinement | miniaturization of C fiber and its examination are performed. Experiments were carried out by the following two dry etching methods for miniaturization of C fiber.
I Ar ion milling
II O ₂ plasma ashing

  The experimental results and experimental conditions performed by the methods I and II are shown in FIGS. Here, 60 mIn dry etching was experimentally performed.

3. Connection of W rod on C fiber by FIB (FIB fixed C fiber support W wire target)
Here, the examination and experiment of the target production method by different methods using FIB are described.

3-1. FIB Fixed Rod Target Manufacturing Method The FIB fixed C fiber support W wire target has the same structure as the conventional rod target, and is manufactured by a method of fixing the support and the metal wire by W film formation of FIB.
The production is performed by the following procedures I to III, and a schematic diagram is shown in FIG.
I Cross-linking the target to two supports attached to the frame
II Fix both ends of support and target with FIB
III Miniaturize only the target by dry etching. The target metal when the FIB device was inserted was fixed to the fine wire and frame attached to the outside of the support with Ag paste, cut with FIB and fixed with W deposit.

3-2. Fixing the target metal when inserting the FIB device Insert the FIB device into the FIB device by fixing the metal wire with silver paste or the like as shown in FIG.
Except for the extra target part, it is cut with an FIB Ga ion beam. Thereafter, the support and the target are fixed by W film formation of FIB.

3-3. FIB Fixed Rod Target Production Experiment A sample subjected to fixation as described above was inserted, and a C fiber (7 μmφ) support and a W wire target were fixed by FIB W film formation. If the target is cut in the vicinity of the support after being fixed by the W film formation, the portion where the support and the target are fixed by the W film formation is damaged. It is considered that the W wire is slightly stressed at the stage of fixing the W wire before the device is inserted. Therefore, here, the procedure and experimental results of an experiment performed by a method in which the target is cut in the vicinity of the support and then fixed by W film formation will be described.

<Experimental procedure>
The W target fixed by the above-described method is inserted into the FIB apparatus, and a node for distributing stress to the W wire target with the FIB Ga ion beam is made. It is preferable to put several places at a position about 100 μm to 200 μm away from the contact point between the support and the target (FIG. 32). After making the knot, both ends of the W wire are cut off at a position about 50 μm away from the contact point between the support and the target (FIG. 33). Then, W film formation is fixed to the contact point between the support and the W wire target. FIG. 34 shows the support and target fixed by the W film formation.

3-4. Consideration of FIB Fixed Rod Target Fabrication Experiment In the sample of this experiment, the silver paste used for fixing the W wire and the Al wire before inserting the apparatus was adhered to the vicinity of the support. As a result of an equivalent experiment with the sample, the silver paste liquefied by the influence of the Ga ion beam wraps around the back of the support and solidifies again to fix the support and the target. The other end of the sample was bonded to the support by redeposition when a node was made with a Ga ion beam. The target completed in this process is shown in FIG.

1 Frame 2 Polyimide film 3 Target 4 Fiber 5 and 6 Target

Claims (22)

  An X-ray target comprising: a polyimide film wound around and attached to a pair of target attachment frames to an apparatus using the X-ray target; and an Au target formed on the polyimide film between the frames. The X-ray target according to claim 1 , wherein the polyimide film is wound around and attached to the frame without an adhesive. The frame is parallel frame, X-rays target according to claim 1 or 2. The portion of the polyimide film is removed, X-rays target according to any one of claims 1 to 3. The X-ray target according to claim 4 , wherein at least a part of the polyimide film except for a part attached to the frame and a part on which the Au target is formed is removed. The Au volume V _t of the target is 6.2% or more with respect to the volume V _s of the polyimide film is a target support, X-rays target according to any one of claims 1 to 5.   An X-ray target comprising a columnar, rod-shaped, or wire-shaped W target formed on a C fiber.   An X-ray target comprising a rod-shaped or wire-shaped W target cross-linked on a plurality of C fibers. The X-ray target according to claim 7 or 8 , wherein the C fiber is attached to a target attachment frame to an apparatus using the X-ray target. The X-ray target according to claim 9 , wherein the frame is a parallel frame, and the C fiber is bridged between the parallel frames. Wherein W volume V _t of the target is 7.2% or more with respect to the C fiber volume V _s is a target support, X-rays target according to any one of claims 7 to 10. X-ray intensity ratio is 100 or more, X-rays target according to any one of claims 1 to 11. A method for producing an X-ray target, in which a line-shaped Au target is formed on a polyimide film ,
A method for producing an X-ray target, comprising forming the polyimide film on a substrate, forming the Au target on the polyimide film, and peeling the polyimide film together with the Au target from the substrate. The method for producing an X-ray target according to claim 13 , wherein the polyimide film is peeled from the substrate in a liquid. The method for producing an X-ray target according to claim 13 or 14 , wherein a hydrophilic treatment is performed on the substrate before forming the polyimide film. Wherein after formation of the Au target to remove a portion of the polyimide film, a manufacturing method of the X-ray target according to any one of claims 13 to 15. Detached from the substrate of the polyimide film in the liquid, by the target mounting frame to the device for use with X-ray target skim the polyimide film of the solution, according to any one of claims 13 to 16 X A method for producing a line target.   A method for producing an X-ray target, in which a columnar W target is formed on a C fiber. The method for producing an X-ray target according to claim 18 , wherein the columnar W target is deposited on the C fiber.   A method for producing an X-ray target, in which a rod-shaped or wire-shaped W target is formed on a C fiber. The method for producing an X-ray target according to claim 20 , wherein the rod-shaped or wire-shaped W target is crosslinked on a plurality of the C fibers. The method for producing an X-ray target according to any one of claims 18 to 21 , wherein the C fiber is attached to a target attachment frame to an apparatus using the X-ray target.