KR20120012736A - Anti-scatter grid and manufacturing method thereof - Google Patents

Abstract

PURPOSE: An anti-scatter grid and a manufacturing method thereof are provided to easily form a silicon frame of a plurality of vertical partition walls by using a crystalline wet etch process of silicon and an ultraviolet exposure process. CONSTITUTION: An anti-scatter grid(10) includes a vertical partition wall which is parallelly arranged in a vertical crystal face of a crystalline substrate. A silicon frame(11) includes a base common body part which connects a plurality of vertical partition walls. A X-ray absorber metal(20) is formed on the silicon frame. A scattering X-ray(32) generated by an subject(40) is dampened with the X-ray absorber metal of the vertical partition walls. A X-ray(33) arrives in a X-ray detector(50) passing through a transmitting material(25). The X-ray absorber metal is composed of nickel, copper, gold, and aluminum etc.

Description

Non-scattering grid and manufacturing method thereof {ANTI-SCATTER GRID AND MANUFACTURING METHOD THEREOF}

The present invention relates to a method for manufacturing a non-scattered grid, a method for manufacturing a non-scattered grid stacked structure, a non-scattered grid and a non-scattered grid stacked structure, more specifically, an ultraviolet exposure process, crystalline wet etching of crystalline silicon substrate and metal By using the semiconductor process including the electroplating process, it is possible to produce more precisely than the conventional technology, so that the image with high contrast and resolution can be obtained, and it is suitable for mass production through the batch process which is the characteristic of semiconductor process technology. The present invention relates to a non-scattered grid manufacturing method, a method for manufacturing a non-scattered grid laminated structure, a non-scattered grid, and a non-scattered grid stacked structure, which can reduce the exposure of the patient due to less absorption of the main X-rays.

1 is a schematic diagram of an X-ray imaging system including a non-scattering grid according to the prior art (US Pat. No. 5,557,650).

X-ray imaging systems are widely used in medical, security screening, nondestructive testing, and scientific research for patient diagnosis. The X-ray imaging system including the non-scattering grid according to the prior art is composed of the X-ray source 30, the subject 40, the non-scattering grid 70, the X-ray detector 50. In the X-ray 31 emitted from the conventional X-ray source 30, the scattering X-rays 32 are generated by the subject 40, which is the wrong position of the X-ray detector 50. The quality of the image obtained by transferring the image information of the subject 40 to the subject is lowered. The X-ray imaging system uses the non-scattering grid 70 to attenuate the scattering X-rays 32 generated by the subject 40 so that the image is reduced. To improve the quality of the.

However, since the non-scattering grid 70 according to the prior art generally uses a plastic or carbon substrate as the X-ray transmissive body 72, the main X-ray 33 is attenuated and attenuated. In order to compensate the line 33, there is a problem inevitably increase the exposure amount to the subject 40. In addition, since the mechanical cutting process is used in the manufacturing method, it is difficult to precisely manufacture the X-ray absorber 71. Such a method has an advantage of manufacturing the non-scattering grid 70 in a large area, but has a disadvantage in that it is difficult to precisely manufacture and the process time is not suitable for mass production.

In order to solve this problem, U.S. Patent No. 6,987,836 discloses a method of forming a groove at a predetermined interval in an X-ray photosensitive film by an X-ray exposure process and embedding a metal, which is an X-ray absorber 71, by an electroforming process. Is disclosed.

The non-scattered grid 70 manufactured in this way has the advantage of being able to manufacture precise vertical bulkheads quickly because it uses an X-ray exposure process having a high energy, but the synchrotron X-ray source used in the X-ray exposure process There is a disadvantage in that an expensive large-scale facility is required to produce the product. Currently, the synchrotron X-ray source in Korea is the only radiation accelerator in the Accelerator Laboratory of Pohang University.

In addition, in the "Fabrication of Antiscatter Grids and Collimators for X-ray and Gamma-ray Imaging by Lithography and Electroforming" by Olga V. Makarova et al. In the case of the scattering grid 70, since the X-ray transmissive body 72 is air, the attenuation of the main X-ray 33 does not occur, but since the X-ray exposure process is used, as described above, X-ray exposure There was a problem that expensive large-scale facilities for producing synchrotron X-ray sources were needed for the process.

An object of the present invention is to manufacture a non-scattered grid using semiconductor processing technology to mass-produce a precise non-scattered grid at low cost.

It is another object of the present invention to form a vertical structure crystallographically very easily along the vertical (111) crystal plane of the (110) crystalline silicon substrate in producing a non-scattered grid having a vertical partition wall.

In addition, in case of using the conventional X-ray exposure process, a synchrotron X-ray source using an expensive radiation accelerator only in the Accelerator Laboratory of Pohang University in Korea should be used, but in the present invention, it is sufficiently implemented as an ultraviolet exposure process of a general semiconductor process. It is another object to make this possible.

Further, another object is to obtain a high aspect ratio easily by stacking a non-scattering grid having a low aspect ratio by arranging and stacking the non-scattering grid in the x direction and the y direction to produce a final non-scattering grid stack structure. .

In addition, the air between each vertical bulkhead of the non-scattering grid serves as an X-ray penetrating member, which increases the exposure amount to compensate for attenuation of the X-rays when using a conventional plastic or carbon substrate as the X-ray penetrating member. It is another object to solve the problem and consequently to reduce the exposure of the patient.

The present invention has been made to solve the above problems, the non-scattered grid manufacturing method according to a first embodiment of the present invention, (a) preparing a crystalline substrate; (b) forming a thin film for an etching mask on the crystalline substrate; (c) forming a photoresist film on the etching mask thin film; (d) patterning the photosensitive film so as to form a silicon skeleton having a second vertical etch to etch the crystalline substrate so as to form a silicon skeleton having vertical bulkheads aligned parallel to a vertical crystal plane and interconnecting the plurality of vertical bulkheads to each other; (e) transferring the pattern of the patterned photoresist onto the thin film for etching mask through a first etching process; (f) forming a silicon skeleton through a second etching process, the silicon substrate having a vertical bulkhead aligned parallel to a vertical crystal plane and having a bottom common portion connecting the plurality of vertical bulkheads to each other; And (g) forming an X-ray absorber metal on the silicon skeleton.

Here, it is preferable that the crystalline substrate is a (110) crystalline silicon substrate, and the vertical crystal plane is a vertical (111) crystal plane of the (110) crystalline silicon substrate.

It is preferable that a said 1st etching process is an anisotropic dry etching process.

It is preferable that a said 2nd etching process is a crystalline wet etching process.

Step (g) may include depositing a conductive metal thin film on the silicon skeleton; And growing the X-ray absorber metal on the silicon skeleton through an electroplating process.

In the step (d), it is preferable to pattern the photosensitive film through an ultraviolet exposure and development process.

On the other hand, the method for producing a non-scattered grid laminate structure according to the second embodiment of the present invention, as a result of laminating a plurality of non-scattered grid produced by the above-described non-scattered grid manufacturing method in a direction perpendicular to each other, A scatter grid lamination structure is produced.

Here, the non-scattered grid stack structure, it is preferable to stack the same number of non-scattered grid cross each other in a direction perpendicular to each other.

In addition, the non-scattering grid according to the third embodiment of the present invention, the silicon skeleton having a vertical partition wall aligned parallel to the vertical crystal plane of the crystalline substrate, and having a base common portion connecting the plurality of vertical partition walls to each other; And an X-ray absorber metal formed on the silicon skeleton.

Here, it is preferable that the crystalline substrate is a (110) crystalline silicon substrate, and the vertical crystal plane is a vertical (111) crystal plane of the (110) crystalline silicon substrate.

The X-ray absorber metal may be formed by depositing a conductive metal thin film on the silicon skeleton and growing the X-ray absorber metal on the silicon skeleton through an electroplating process.

In addition, the non-scattered grid stack structure according to the fourth embodiment of the present invention, a plurality of non-scattered grid according to the third embodiment is provided by crossing and stacked in a direction perpendicular to each other. Likewise, in the non-scattered grid stack structure, it is preferable that the same number of non-scattered grids are stacked to cross each other in a direction perpendicular to each other.

According to the present invention, it is possible to form a vertical structure crystallographically very easily along the vertical (111) crystal plane of the (110) crystalline silicon substrate.

In addition, the (110) crystalline silicon substrate is patterned in parallel to the vertical (110) crystal plane by using an ultraviolet exposure process and a crystalline wet etching process of silicon, so that it is possible to easily create a silicon skeleton of a plurality of vertical partition walls.

In the case of using a conventional X-ray exposure process, a synchrotron X-ray source using an expensive radiation accelerator in Pohang University's accelerator research center should be used in Korea, but in the present invention, it can be sufficiently implemented as an ultraviolet exposure process of a general semiconductor process. The manufacturing cost can be lowered.

Furthermore, the present invention provides a non-scattered grid using a semiconductor process technology including an ultraviolet exposure process, a crystalline wet etching of the crystalline silicon substrate 60 and an electroplating process of a metal in manufacturing a non-scattering grid. It is possible to mass-produce at low cost, while manufacturing precisely. As a result, images with high contrast and resolution can be obtained.

By disposing and stacking the non-scattered grid thus produced in the x direction and the y direction, and manufacturing a final non-scattered grid stack structure, it is possible to easily stack a non-scattered grid having a low aspect ratio to obtain a high aspect ratio.

In addition, the air between each vertical bulkhead of the non-scattering grid serves as an X-ray penetrating member, which increases the exposure amount to compensate for attenuation of the X-rays when using a conventional plastic or carbon substrate as the X-ray penetrating member. The problem can be solved. As a result, the effect of reducing the exposure of the patient can be achieved.

1 is a schematic diagram of an X-ray imaging system including a non-scattering grid according to the prior art.
2 is a schematic diagram of an X-ray imaging system including a non-scattering grid according to the present invention.
3 is a schematic diagram showing a (111) crystal plane of a (110) crystalline silicon substrate.
4A to 4D are views illustrating a method for manufacturing a non-scattered grid and a non-scattered grid laminate structure according to the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in this specification and claims should not be construed in a common or dictionary sense, and the inventors will be required to properly define the concepts of terms in order to best describe their invention. Based on the principle that it can, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention.

Therefore, the embodiments described in the present specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. Therefore, at the time of the present application, It should be understood that there may be water and variations.

2 is a schematic diagram of an X-ray imaging system including a non-scattering grid according to the present invention. 3 is a schematic diagram showing a (111) crystal plane of a (110) crystalline silicon substrate. 4A to 4D are views illustrating a method for manufacturing a non-scattered grid and a non-scattered grid laminate structure according to the present invention.

The non-scattering grid 10 according to the present invention has a vertical bulkhead (part a1 in FIG. 4B) aligned parallel to the vertical crystal plane of the crystalline substrate 60, and the plurality of vertical bulkheads (a1 part in FIG. 4B) are arranged. A silicon skeleton 11 having a base common portion (b1 portion in FIG. 4B) connecting to each other; And an X-ray absorber metal 20 formed on the silicon skeleton 11.

The configuration of the X-ray imaging system is the same as that according to the prior art described with reference to FIG. 1 except that the non-scattering grid 10 according to the present invention is different. In the prior art, the X-ray absorber is composed entirely of metal, but the non-scattering grid 10 of the present invention grows on the silicon skeleton 11, that is, on the top, bottom, and side surfaces thereof. A vertical bulkhead (a2 part in FIG. 4c), a base common part (b2 part in FIG. 4c), and an X-ray penetrating member 25 made of air.

The scattering X-rays 32 generated by the subject 40 are attenuated by the metal 20, which is the X-ray absorber of the vertical bulkhead, and the main X-rays 33 are X-ray transmissive bodies (air) 25 ) To reach the X-ray detector 50. At this time, since the X-ray penetrator 25 is air, absorption of the main X-ray 33 in the X-ray penetrator 32 does not occur.

Therefore, compared to the non-scattering grid 70 according to the prior art using the plastic or carbon substrate described in FIG. 1 as the X-ray transmissive 72, X-ray attenuation in the X-ray transmissive is reduced, thereby attenuating X It is possible to prevent further radiation of X-rays in order to compensate the rays and prevent deterioration of the image quality, thereby reducing the exposure of the patient.

Here, the X-ray absorber metal 20 may be nickel, copper, gold, aluminum, and the like, and among these, the X-ray absorber metal is known to have relatively good gold performance. This is because the X-ray attenuation coefficient is proportional to the atomic number and density of the material.

3 is a schematic diagram showing the vertical (111) crystal planes 61, 62, 63 of the (110) crystalline silicon substrate 60. The (110) crystalline silicon substrate 60 has two vertical (111) crystal planes 61 and 62 and one inclined 111 crystal plane 63. Therefore, when the crystalline etching mask 90 is patterned in parallel to the vertical (111) crystal planes 61 and 62, a vertical structure along the vertical (111) crystal planes 61 and 62 is formed using a crystalline wet etching process. Easy to make

Accordingly, the crystalline wet etching process using the vertical (111) crystal planes 61 and 62 of the (110) crystalline silicon substrate 60 to form the silicon skeleton 11 forming the vertical bulkhead of the non-scattering grid 10 according to the present invention. Produced by

In the present specification, the crystalline substrate is described as a (110) crystalline silicon substrate, and the vertical crystalline plane is assumed to be a vertical (111) crystal plane of the (110) crystalline silicon substrate. Of course it can be used.

Next, with reference to FIG. 4, the manufacturing method of a non-scattering grid is demonstrated. FIG. 4A illustrates a photosensitive film 80 patterned in parallel to the vertical (111) crystal planes 61 and 62 of the (110) crystalline silicon substrate 60 using an ultraviolet (UV) exposure process and an anisotropic dry etching process. It is a schematic diagram which shows the thin film 90 for crystalline wet etching masks on which the pattern of the photosensitive film 80 was transferred.

In order to manufacture the silicon skeleton 11 shown in Figure 4b, first prepare a (110) crystalline substrate (step (a)). Next, after depositing the crystalline wet etching mask thin film 90 on the (110) crystalline silicon substrate 60 (step (b)), the photosensitive film 80 is thin film 90 for the crystalline wet etching mask. (C)).

Next, a vertical partition wall in which the photosensitive film 80 is aligned by using an ultraviolet exposure process and the (110) crystalline substrate 60 is aligned parallel to the vertical (111) crystal plane through a crystalline wet etching process (second etching process). Correspondingly so that it is possible to form a silicon skeleton 11 having a common portion (a portion b1 of FIG. 4b) having a portion (a1 in FIG. 4b) and connecting the plurality of vertical bulkheads (a1 portion in FIG. 4b) to each other. (D)). At this time, since all vertical bulkhead shapes are formed at the same time on the photoresist film 80, the gap between all vertical bulkheads can be precisely manufactured with a very small error.

Next, after the ultraviolet exposure process, the pattern of the photosensitive film 80 patterned in the step (d) is transferred to the thin film 90 for the crystalline wet etching mask by the anisotropic dry etching (first etching) (step (e)). . Before the next step, the crystalline wet etching process, the photoresist film 80 remaining after the step (e) is removed.

Next, through the crystalline wet etching process (second etching process), the plurality of vertical partition walls are formed by having a vertical partition wall (a1 part of FIG. 4B) aligned parallel to the vertical (111) crystal plane of (110) crystalline substrate. A silicon skeleton 11 is formed having a base common portion (b1 portion of FIG. 4B) that connects to each other (step (f)).

FIG. 4B is a bottom common wall having vertical bulkheads (part a1 in FIG. 4B) aligned parallel to the vertical (111) crystal planes 61, 62 of the (110) crystalline silicon substrate 60 and connecting the plurality of vertical bulkheads to each other. It is a schematic diagram which shows the silicon skeleton 11 which has a part (b1 part of FIG. 4B). In the case of crystalline silicon, since the etching speed of the (111) crystal plane is the slowest, the thin film 90 for an etching mask naturally aligned parallel to the vertical (111) crystal planes 61 and 62 of the (110) crystalline silicon substrate 60. The vertical silicon skeleton 11 can be easily and precisely formed by a crystalline wet etching process along the pattern. In the case of crystalline wet etching, processing along the crystallographic side results in a very precise vertical structure compared to any other vertical structure fabrication technique.

4C is a schematic diagram showing the X-ray absorber metal 20 grown on the silicon skeleton 11. Since the (110) crystalline silicon substrate 60 itself has a relatively inferior X-ray attenuation capability compared to metal, silicon having a silicon skeleton 11 as a basic structure to attenuate scattering X-rays 32 The non-scattering grid according to the invention is formed by growing an X-ray absorber metal 20 on the armature 11, including the top, bottom and side surfaces, using an electroplating process around the silicon armature 11. Complete (step (g)).

In this case, when the metal is grown on the surface of the silicon substrate by the electroplating process, the growth rate is negligible so that the metal is not immediately grown on the surface of the silicon substrate, and the conductive metal thin film is deposited before the electroplating process. , Metal is grown by electroplating process. During the deposition of the conductive metal thin film, the upper and lower surfaces of the silicon skeleton 11 are also deposited on the upper and lower surfaces thereof. Thus, during the electroplating process, the X-ray absorber metal 20 is grown on both the sides, the upper surface, and the lower surface of the silicon skeleton 11.

In addition, since the space between the vertical bulkheads (a2 part in FIG. 4C) is air, the air serves as the X-ray transmissive material 25. As a result, absorption of the main X-ray 33 by air is very small, and the exposure amount of the subject 40 can be reduced.

FIG. 4D alternately stacks a non-scattering grid having a one-dimensional vertical bulkhead (a2 portion of FIG. 4C) and a base common portion (b2 portion of FIG. 4C) having a low aspect ratio to obtain a high aspect ratio. It is a schematic diagram which shows the two-dimensional non-scattering grid laminated structure which has.

Since the non-scattering grid according to the present invention has a one-dimensional array (21, 22), the scattering X-rays 32 incident in parallel to the vertical partition in which the X-ray absorber metal 20 is grown cannot be attenuated. Therefore, in order to attenuate scattering X-rays 32 incident in all directions, one-dimensional non-scattering grids are alternately stacked and two-dimensionally arranged.

In addition, to achieve a high aspect ratio (low aspect ratio) vertical barrier ribs of low aspect ratio is laminated in multiple layers. In general, it is preferable to make a non-scattered grid stack structure by stacking the same number of non-scattering grids in a direction perpendicular to each other (x direction, y direction).

Here, the non-scattering grids stacked alternately with each other may be separated from each other up or down, or may be laminated directly.

Alternatively, the non-scattering grid may be stacked in order in the order of x-direction non-scattering grid, y-direction non-scattering grid, x-direction non-scattering grid, y-direction non-scattering grid, and so on. The non-scattering grid may be stacked in a batch, and then the y-direction non-scattering grid may be stacked in a batch. Of course, various changes and variations can be made to the non-scattering grid stacking order.

As such, the non-scattered grid laminate structure according to the present invention has the advantage that the height can be easily adjusted and the required aspect ratio can be easily obtained, so that the scattering X-ray absorption ability is easier to control compared to the prior art.

As described above, although the present invention has been described by way of limited embodiments and drawings, the present invention is not limited thereto and is intended by those skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of equivalents of the claims to be described.

10: non-scattering grid
11: Silicon armature of vertical bulkhead aligned parallel to vertical (111) crystal plane of (110) crystalline silicon substrate
20: X-ray absorber metal
21: non-scattering grid with vertical bulkhead in y direction
22: Non-scattering grid with vertical bulkhead in x direction
25: X-Ray Transmitter Material (Air)
30: X-ray source 31: X-ray radiated from the X-ray source to the subject
32: scattering X-ray 33: main X-ray
40: subject 50: X-ray detector
60: (110) crystalline silicon substrate
61: first vertical (111) crystal plane of (110) crystalline silicon substrate
62: second vertical (111) crystal plane of (110) crystalline silicon substrate
63: inclined (111) crystal plane of (110) crystalline silicon substrate
70: prior art non-scattering grid
71: X-ray absorber metal in the prior art
72: X-ray transmission material in the prior art
80: photosensitive film 90: thin film for crystalline wet etching mask

Claims (13)

(a) preparing a crystalline substrate;
(b) forming a thin film for an etching mask on the crystalline substrate;
(c) forming a photoresist film on the etching mask thin film;
(d) patterning the photosensitive film so as to form a silicon skeleton having a second vertical etch to etch the crystalline substrate so as to form a silicon skeleton having vertical bulkheads aligned parallel to a vertical crystal plane and interconnecting the plurality of vertical bulkheads to each other;
(e) transferring the pattern of the patterned photoresist onto the thin film for etching mask through a first etching process;
(f) forming a silicon skeleton through a second etching process, the silicon substrate having a vertical bulkhead aligned parallel to a vertical crystal plane and having a bottom common portion connecting the plurality of vertical bulkheads to each other; And
(g) forming an X-ray absorber metal on the silicon skeleton. The method of claim 1,
The crystalline substrate is a (110) crystalline silicon substrate,
And said vertical crystal plane is a vertical (111) crystal plane of said (110) crystalline silicon substrate. The method of claim 1,
The first etching process is an anisotropic dry etching process, characterized in that the non-scattered grid manufacturing method. The method of claim 1,
The second etching process is a non-scattering grid manufacturing method, characterized in that the crystalline wet etching process. The method of claim 1,
The step (g)
Depositing a conductive metal thin film on the silicon skeleton; And
Growing the X-ray absorber metal on the silicon skeleton through an electroplating process. The method of claim 1,
In the step (d), the non-scattered grid manufacturing method, characterized in that for patterning the photosensitive film through an ultraviolet exposure and development process. Non-scattering fabricating a non-scattering grid laminate structure as a result of stacking a plurality of non-scattering grids produced by the non-scattering grid manufacturing method according to any one of claims 1 to 6 in a direction perpendicular to each other. Method for manufacturing grid laminated structure. The method of claim 7, wherein
A method for producing a non-scattered grid laminate structure, characterized in that the same number of non-scattering grids are laminated in a direction perpendicular to each other. A silicon skeleton having vertical bulkheads aligned parallel to a vertical crystal plane of a crystalline substrate and having a base common portion connecting the plurality of vertical bulkheads to each other; And
A non-scattering grid comprising an X-ray absorber metal formed on the silicon skeleton. The method of claim 9,
The crystalline substrate is a (110) crystalline silicon substrate,
And the vertical crystal plane is a vertical (111) crystal plane of the (110) crystalline silicon substrate. The method of claim 9,
And the X-ray absorber metal is formed by depositing a conductive metal thin film on the silicon skeleton and growing the X-ray absorber metal on the silicon skeleton through an electroplating process. The non-scattering grid laminated structure which laminated | stacked and laminated | stacked the several non-scattering grid of any one of Claims 9-11 in the direction perpendicular to each other. The method of claim 12,
Non-scattered grid laminated structure, characterized in that the same number of non-scattered grids stacked in a direction perpendicular to each other.

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