JP5533296B2 - Semiconductor X-ray detection element, manufacturing method thereof, and semiconductor X-ray detection sensor - Google Patents

Description

  The present invention relates to a semiconductor X-ray detection element, a manufacturing method thereof, and a semiconductor X-ray detection sensor. More specifically, the present invention relates to a semiconductor X-ray detection element in which the drift layer does not spread to the bottom surface on the signal extraction electrode side of the semiconductor X-ray detection element even if the drift layer is thickened, and a method for manufacturing the same. Furthermore, the present invention relates to a semiconductor X-ray detection sensor in which no impure line appears in the detected X-ray spectrum.

  Conventionally, an n + layer and an n-plane electrode in which lithium is diffused are provided in the central portion of one bottom surface of a cylindrical p-type semiconductor crystal (hereinafter referred to as a tablet), and the peripheral portions of the n + layer and the n-plane electrode are shaved. A groove is provided to reduce the area of the n + layer and the n-plane electrode, and reverse bias is applied to drift lithium to form a substantially cylindrical i layer (a shape obtained by cutting two parallel surfaces from a sphere). A method for manufacturing a semiconductor X-ray detection element is known in which a p-layer is left so as to substantially cover the peripheral surface of the p-type semiconductor tablet, and finally a p-plane electrode is formed on the other bottom surface of the p-type semiconductor tablet. .

International Publication No. WO2007 / 138745

In the above-described conventional method for manufacturing a semiconductor X-ray detection element, if the i layer is thickened, the drift of lithium in the radial direction of the p-type semiconductor tablet also increases, so that the i layer is formed on the bottom surface of the p-type semiconductor tablet on the n-plane electrode side. There is a problem that it becomes impossible to hold the semiconductor X-ray detection element by pushing the peripheral edge of the bottom surface on the n-plane electrode side of the manufactured semiconductor X-ray detection element with an element fixture (thereby increasing the leakage current) Etc.).
For this reason, in a conventional semiconductor X-ray detection sensor using a semiconductor X-ray detection element, a metal pin that also serves as a signal extraction line is brought into contact with the element holder on the p-side electrode side periphery of the semiconductor X-ray detection element The n-plane electrode of the semiconductor X-ray detection element is pressed and the semiconductor X-ray detection element is held so as to be sandwiched.
However, X-rays transmitted through the semiconductor X-ray detection element are incident on the metal pin, and the characteristic X-rays of the elements constituting the metal pin generated in that portion are incident on the semiconductor detection element, thereby detecting the detected X-ray. There was a problem that an impure line appeared in the line spectrum.
Accordingly, an object of the present invention is to spread the drift layer (i layer) to the bottom surface of the semiconductor tablet (p-type semiconductor tablet) on the signal extraction electrode (n-plane electrode) side even if the drift layer (i layer) is thickened. An object of the present invention is to provide a semiconductor X-ray detection element having no defect and a method for manufacturing the same. Another object of the present invention is to provide a semiconductor X-ray detection sensor in which no impure line appears in the detected X-ray spectrum.

In the first aspect, the present invention provides a cylindrical recess (9) provided in a central portion of one bottom surface of a cylindrical semiconductor tablet (30), and an n-plane in a central portion of the bottom surface of the recess (9). Provided is a semiconductor X-ray detection element (10) characterized in that an electrode (3) is provided.
In the semiconductor X-ray detection element (10) according to the first aspect, one bottom surface (5a) of the semiconductor tablet (30) remaining so as to surround the recess (9) is the other bottom surface of the semiconductor tablet (30). From the n-plane electrode (3). Therefore, even if the drift layer (1) is thickened and the drift layer (1) spreads in the radial direction of the semiconductor tablet (30), one of the semiconductor tablets (30) remaining so as to surround the recess (9) The drift layer (1) does not spread to the bottom surface (5a). Accordingly, the bottom surface (5a) of the semiconductor tablet (30) remaining so as to surround the recess (9) can be pushed by the element fixing tool so as to hold the semiconductor X-ray detection element (10). (This will not cause inconvenience such as an increase in leakage current.) Therefore, for example, a wire can be connected to the n-plane electrode (3) without using a metal pin, and X-rays are incident on the metal pin, and the characteristic X of the element constituting the metal pin generated in that portion The problem that the impure line appears in the detected X-ray spectrum can be solved by making the line incident on the semiconductor detection element.
In addition, in order to obtain a sufficient level | step difference, it is preferable that the depth of a recessed part (9) shall be 0.5 mm or more.

In a second aspect, the present invention provides a cylindrical recess (9) in the central portion of one bottom surface of a cylindrical p-type semiconductor tablet (30), and diffuses lithium into the bottom surface of the recess (9). In addition, an n + layer (91) and an n-plane electrode (92) are provided, a reverse bias is applied to form an i-layer (1), and the areas of the n + layer (91) and the n-plane electrode (92) are reduced. Provided is a method for manufacturing a semiconductor X-ray detection element, wherein an n + layer (2) and an n-plane electrode (3) are formed.
In the method for manufacturing a semiconductor X-ray detection element according to the second aspect, since the n + layer (91) and the n-plane electrode (92) are provided in the central portion of the bottom surface of the recess (9), the recess (9) is surrounded. One bottom surface (5a) of the remaining p-type semiconductor tablet (30) is farther from the other bottom surface of the p-type semiconductor tablet (30) than the n + layer (91) and the n-plane electrode (92). . Therefore, even if the i layer (1) is thickened and the i layer (1) spreads in the radial direction of the p type semiconductor tablet (30), the p type semiconductor tablet (30) remaining so as to surround the recess (9). I layer (1) does not spread to one bottom surface (5a). Accordingly, the bottom surface (5a) of the semiconductor tablet (30) remaining so as to surround the recess (9) can be pushed by the element fixing tool so as to hold the semiconductor X-ray detection element (10). (This will not cause inconvenience such as an increase in leakage current.) Therefore, for example, a wire can be connected to the n-plane electrode (3) without using a metal pin, and X-rays are incident on the metal pin, and the characteristic X of the element constituting the metal pin generated in that portion The problem that the impure line appears in the detected X-ray spectrum can be solved by making the line incident on the semiconductor detection element.
Further, since the reverse bias is applied to the n + layer (2) and the n-plane electrode (3) before reducing the area, the i-layer (1) can be formed quickly, and then the n + layer (2) and the n-plane electrode are formed. Since the area of (3) is reduced, the element capacitance is reduced and high resolution can be achieved.

In a third aspect, the present invention provides a cylindrical recess (9) in the central portion of one bottom surface of the cylindrical p-type semiconductor tablet (30), and the central portion of the bottom surface of the recess (9). An n + layer (2) and an n-plane electrode (3) are provided, and the p-type semiconductor tablet (30) has a structure in which a p layer (5) surrounds the i layer (1), and the recess (9) is formed. All or part of the ring-shaped shoulder (5a) which is the bottom surface surrounding the ring-shaped shoulder (5a) and the ring-shaped bottom (5b) corresponding to the opposite surface of the ring-shaped shoulder (5a) is a p-layer (5). A semiconductor X-ray detection element (10) is provided.
In the semiconductor X-ray detection element (10) according to the third aspect, one bottom surface (5a) of the p-type semiconductor tablet (30) remaining so as to surround the recess (9) is the other side of the semiconductor tablet (30). Is separated from the bottom surface by a step more than the n-plane electrode (3). Therefore, even if the i layer (1) is thickened and the i layer (1) spreads in the radial direction of the p type semiconductor tablet (30), the p type semiconductor tablet (30) remaining so as to surround the recess (9). I layer (1) does not spread to one bottom surface (5a). Therefore, one bottom surface (5a) of the p-type semiconductor tablet (30) remaining so as to surround the recess (9) can be held by pressing the element fixing tool so as to sandwich the semiconductor X-ray detection element (10). (In this case, there will be no inconvenience such as an increase in leakage current). Therefore, for example, a wire can be connected to the n-plane electrode (3) without using a metal pin, and X-rays are incident on the metal pin, and the characteristic X of the element constituting the metal pin generated in that portion The problem that the impure line appears in the detected X-ray spectrum can be solved by making the line incident on the semiconductor detection element.

In a fourth aspect, the present invention relates to a portion of the p-layer (5) of the ring-shaped shoulder (5a) and the ring-shaped bottom (5b) of the semiconductor X-ray detection element (10) according to the third aspect. Provided is a semiconductor X-ray detection sensor (100) characterized by being held so as to sandwich the semiconductor X-ray detection element (10).
In the semiconductor X-ray detection sensor (100) according to the fourth aspect, the bottom surface (5a) of the p-type semiconductor tablet (30) remaining so as to surround the recess (9) is pushed by an element fixing tool. Since the line detection element (10) is held so as to be sandwiched, it is not necessary to use a metal pin, and for example, a wire can be connected to the n-plane electrode (3). Therefore, X-rays are incident on the metal pin, and the characteristic X-rays of the elements constituting the metal pin generated in that portion are incident on the semiconductor detection element, so that an impure line appears in the detected X-ray spectrum. Can be solved.

In a fifth aspect, the present invention provides a semiconductor X-ray detection sensor (100) according to the fourth aspect, wherein a wire (21) is attached to the n-plane electrode (3) of the semiconductor X-ray detection element (10). A semiconductor X-ray detection sensor (100) characterized by being connected is provided.
In the semiconductor X-ray detection sensor (100) according to the fifth aspect, the bottom surface (5a) of the p-type semiconductor tablet (30) remaining so as to surround the recess (9) is pushed by the element fixing tool. The wire detection element (10) is held so as to sandwich the wire, and the wire is connected to the n-plane electrode (3) without using a metal pin. As a result, X-rays are incident on the metal pin, and the characteristic X-rays of the elements constituting the metal pin generated in that portion are incident on the semiconductor detection element, so that an impurity line appears in the detected X-ray spectrum. Can solve the problem.

According to the semiconductor X-ray detection element of the present invention, since the cylindrical recess is provided in the central portion of one bottom surface of the cylindrical semiconductor tablet, and the n-plane electrode is provided in the central portion of the bottom surface of the recess, drift is caused. Even if the layer is thickened, the drift layer does not spread to the bottom surface of the semiconductor tablet on the n-plane electrode side.
According to the semiconductor X-ray detection sensor of the present invention, the one bottom surface of the p-type semiconductor tablet remaining so as to surround the recess is pushed by the element fixture and held so as to sandwich the semiconductor X-ray detection element. There is no need to use a pin, and for example, a wire can be connected to an n-plane electrode. Therefore, X-rays are incident on the metal pin, and the characteristic X-rays of the elements constituting the metal pin generated in that portion are incident on the semiconductor detection element, so that an impure line appears in the detected X-ray spectrum. Can be solved.

1 is a cross-sectional view showing a semiconductor X-ray detection element according to Example 1. FIG. FIG. 3 is a flowchart showing a method for manufacturing a semiconductor X-ray detection element according to Example 1. It is sectional drawing of a p-type semiconductor tablet. It is explanatory drawing which shows the front | former stage of a recessed part formation process. It is explanatory drawing which shows the back | latter stage of a recessed part formation process. It is explanatory drawing which shows a n + layer formation process. It is explanatory drawing which shows the front | former stage of an n-plane electrode formation process. It is explanatory drawing which shows the back | latter stage of an n-plane electrode formation process. It is explanatory drawing which shows the front | former stage of i layer formation process. It is explanatory drawing which shows the back | latter stage of an i layer formation process. It is explanatory drawing which shows the area reduction process of an n + layer and an n surface electrode. It is explanatory drawing which shows a p-plane electrode (Au) formation process. It is explanatory drawing which shows an incident window formation process. It is explanatory drawing which shows a p-plane electrode (Ni) formation process. It is explanatory drawing which shows a protective film formation process. FIG. 6 is a cross-sectional view showing a main part of a semiconductor X-ray detection sensor according to Example 2.

  Hereinafter, the present invention will be described in more detail with reference to the embodiments shown in the drawings. Note that the present invention is not limited thereby.

Example 1
FIG. 1 is a cross-sectional view illustrating a semiconductor X-ray detection element 10 according to the first embodiment.
This semiconductor X-ray detection element 10 includes a cylindrical recess 9 provided in the central portion of one bottom surface of a cylindrical p-type semiconductor tablet 30, an n + layer 2 provided in the central portion of the bottom surface of the recess 9, and The n-plane electrode 3, the substantially cylindrical i-layer 1 formed at the center of the p-type semiconductor tablet 30, the p-layer 5 surrounding the i-layer 1, and the center of one bottom surface of the p-type semiconductor tablet 30 An X-ray incident window 6 provided in the part, a p-plane ring electrode 4 formed on the bottom surface surrounding the X-ray incident window 6, a p-plane electrode 7 formed on one bottom surface of the p-type semiconductor tablet 30, and a protective film 8 that covers the surface of the recess 9 except for the n-plane electrode 3.
In addition, 5a is a ring-shaped shoulder part which is the bottom face surrounding the recessed part 9. FIG. Reference numeral 5b denotes a ring-shaped bottom portion facing the ring-shaped shoulder portion 5a.

  As a numerical example, the diameter of the p-type semiconductor tablet 30 is about 10 mm, the thickness of the p-type semiconductor tablet 30 is about 4 mm, the diameter of the recess 9 is about 7 mm, and the depth of the recess 9 is about 1.1 mm, the diameter of the n + layer 2 and the n-plane electrode 3 is about 1 mm, the diameter of the X-ray entrance window 6 is about 7 mm, and the depth of the X-ray entrance window 6 is about 0.1 mm. is there.

FIG. 2 is a flowchart showing a process of manufacturing the semiconductor X-ray detection element 10.
In step S1, a cylindrical recess 90 as shown in FIG. 4 is formed on the upper surface of the cylindrical p-type semiconductor tablet 30 as shown in FIG. 3 by ultrasonic machining. The diameter of the recess 90 is about 5.8 mm, and the depth of the recess 90 is about 0.5 mm. Next, as shown in FIG. 5, etching is performed with fluorinated acetic acid to remove the ultrasonic damage layer on the surface of the recess 90, thereby forming the recess 9. If the depth removed by etching is about 0.3 mm, for example, the diameter of the recess 9 is about 6.4 mm, and the depth of the recess 9 is about 0.8 mm. It should be noted that a mask using wax or the like is provided for a portion that is not desired to be etched.
The p-type semiconductor tablet 30 is obtained, for example, by cutting a p-type Si wafer into the outer shape (tablet) of the semiconductor X-ray detection element 10 and mirror-polishing both bottom surfaces.

In step S2, Li is vacuum-deposited on the surface of the recess 9, and Li is thermally diffused to form an n ⁺ layer 91 as shown in FIG. The depth of Li diffusion is about 0.1 mm. Thereafter, excess Li remaining on the surface of the recess 9 is removed by etching with hydrofluoric acid.

  In step S3, an n-plane electrode 92 is formed on the surface of the recess 9 by, for example, continuous vacuum deposition of Ni and Au as shown in FIG.

  In step S4, as shown in FIG. 8, the n + layer 91 and the n-plane electrode 92 on the side surface of the recess 9 are removed by ultrasonic processing, and further, the damage layer due to ultrasonic waves is removed by etching with hydrofluoric acid. Etching with fluorinated acetic acid is performed for about 10 minutes, for example. If the depth removed by etching is about 0.3 mm, for example, the diameter of the recess 9 is about 7 mm, and the depth of the recess 9 is about 1.1 mm.

  In step S5, a reverse bias is applied while the temperature is raised to cause Li to drift, thereby forming an i-layer 93 having a substantially cylindrical shape (a shape obtained by cutting two parallel surfaces from a sphere) as shown in FIG. The p layer 5 is left in a donut shape around the i layer 93.

  In step S6, the bottom surface of the p-type semiconductor tablet 30 is polished so that the exposed area of the i layer becomes a desired area, and the i layer 1 is formed as shown in FIG. For example, the bottom surface of the p-type semiconductor tablet 30 is polished by about 0.5 mm so that the exposed area of the i layer becomes 20 square mm.

In step S7, the peripheral portions of the n ⁺ layer 91 and the n-plane electrode 92 are removed by ultrasonic machining and fluorinated acetic acid etching to form the n ⁺ layer 2 and the n-plane electrode 3 having a reduced area as shown in FIG. To do. The reduced areas of the n ⁺ layer 2 and the n-plane electrode 3 are, for example, 3 mm 2.

  In step S8, as shown in FIG. 12, Au is vacuum-deposited on the bottom surface of the p-type semiconductor tablet 30 to form the p-plane electrode 94.

  In step S9, as shown in FIG. 13, the X-ray incident window 6 is formed by etching, for example. Thereby, the p-plane electrode 94 becomes the p-plane ring electrode 4.

  In step S10, Ni is vacuum-deposited on the bottom surface of the p-type semiconductor tablet 30, as shown in FIG.

  In step S11, as shown in FIG. 15, for example, a silicon-based resin is applied to form the protective film 8.

  According to the semiconductor X-ray detection element 10 of the first embodiment, the ring-shaped shoulder 5 a is separated from the other bottom surface of the semiconductor tablet 30 with a step more than the n-plane electrode 3. For this reason, even if the i layer 1 is thickened and the i layer 1 spreads in the radial direction of the p-type semiconductor tablet 30, the i layer 1 does not spread to the ring-shaped shoulder 5a.

-Example 2-
FIG. 16 is a cross-sectional view of main parts of a semiconductor X-ray detection sensor 100 according to the second embodiment.
In this semiconductor X-ray detection sensor 100, the ring-shaped bottom 5b of the semiconductor X-ray detection element 1 according to the first embodiment is brought into contact with the BN element holder 11, the ring-shaped shoulder 5a is pushed by the BN element fixing tool 12, and BN A configuration in which the semiconductor X-ray detection element 10 is held so as to be sandwiched by a metal ring 13 built in the element fixture 12, and an Au wire 21 is connected to the n-plane electrode 3 to extract a signal to the FET chip 22. It is.

  According to the semiconductor X-ray detection sensor 100 according to the second embodiment, since the Au wire 21 is connected to the n-plane electrode 3 and no metal pin is used, X-rays are incident on the metal pin and are generated there. When the characteristic X-rays of the elements constituting the metal pin are incident on the semiconductor detection element, the problem of impure lines appearing in the detected X-ray spectrum does not occur. In addition, since the area of the n-plane electrode 3 can be reduced to the minimum area to which the Au wire 21 can be connected, the resolution can be improved.

-Example 3-
Using a cylindrical tablet of high purity and high resistance Si crystal, for example, boron is diffused from the peripheral surface of the tablet to form a donut-shaped p layer 5, and the cylindrical i layer 1 is surrounded by the p layer 5. You may leave.

  The semiconductor X-ray detection element and the semiconductor X-ray detection sensor of the present invention can be used as a detector of an energy dispersive X-ray analyzer.

DESCRIPTION OF SYMBOLS 1 i layer 2 n + layer 3 n surface electrode 4 p surface ring electrode 5 p layer 5a ring-shaped shoulder part 5b ring-shaped bottom part 6 X-ray incident window 7 p surface electrode 8 protective film 9 recessed part 10 semiconductor X-ray detection element 11 BN element Holder 12 BN element fixture 13 Metal ring 21 Au wire 100 Semiconductor X-ray detection sensor

Claims (5)

A cylindrical recess (9) is provided in the central portion of one bottom surface of the cylindrical semiconductor tablet (30), and an n-plane electrode (3) is provided in the central portion of the bottom surface of the recess (9) , One bottom surface (5a) of the semiconductor tablet (30) remaining so as to surround the recess (9) is separated from the other bottom surface of the semiconductor tablet (30) by a step more than the n-plane electrode (3), The semiconductor X-ray detection element (10), wherein the drift layer (1) does not extend to one bottom surface (5a) of the semiconductor tablet (30 ). An n + layer (91) and an n-plane electrode in which a cylindrical recess (9) is provided at the center of one bottom surface of a cylindrical p-type semiconductor tablet (30) and lithium is diffused in the bottom surface of the recess (9) (92), reverse bias is applied to form the i layer (1), and the areas of the n + layer (91) and the n-plane electrode (92) are further reduced to reduce the n + layer (2) and the n-plane electrode ( 3) forming a semiconductor X-ray detecting element. A cylindrical recess (9) is provided at the center of one bottom surface of the cylindrical p-type semiconductor tablet (30), and an n + layer (2) and an n-plane electrode ( 3), and the p-type semiconductor tablet (30) has a structure in which the p layer (5) surrounds the i layer (1), and a ring-shaped shoulder (5a) that is a bottom surface surrounding the recess (9). ) and the ring Jokata section (p layer all or a portion of the ring-shaped bottom portion corresponding to the opposite side (5b) of 5a) (5) der is, the ring Jokata portion (5a) is p-type semiconductor tablet A semiconductor X-ray characterized in that the i-layer (1) does not extend from the other bottom surface of (30) to the ring-shaped shoulder (5a) with a step difference from the n-plane electrode (3). Detection element (10). The semiconductor X-ray detection element (10) at the p-layer (5) of the ring-shaped shoulder (5a) and the ring-shaped bottom (5b) of the semiconductor X-ray detection element (10) according to claim 3. A semiconductor X-ray detection sensor (100) characterized by being held so as to be sandwiched. The semiconductor X-ray detection sensor (100) according to claim 4, wherein a wire (21) is connected to the n-plane electrode (3) of the semiconductor X-ray detection element (10). Sensor for detection (100).

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