JP2018137255A - Method of manufacturing electronic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method capable of easily manufacturing a through electrode.SOLUTION: When forming an isolation region for insulating a through electrode composed of a substrate from the surrounding substrate, the interior of the through hole is filled with an oxide and a part of the substrate left between through holes is insulated by forming a plurality of through-holes in an isolation region formation region and performing thermal oxidization. Furthermore, an extension part is formed at the end of the through hole, and a part of the substrate left between the through holes is surely insulated.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method for manufacturing an electronic device including a through electrode.

  In recent years, electronic devices have been downsized, and electronic devices to be mounted are also desired to be downsized and thinned. As one method for reducing the size of an electronic device, a method of forming an electrical connection of an electronic device by a through electrode called TSV (Through Silicon Via) that penetrates a silicon substrate has been proposed.

  A conventional through electrode will be described. FIG. 5 is a cross-sectional view of a conventional through electrode. An inner wall surface of a through hole 22 formed so as to penetrate the substrate 21 is covered with an insulating film 23 and insulated from the substrate 21. A metal 24 such as copper formed using a plating method or the like is embedded in the through hole 22, and the metal 24 serves as a through electrode to connect the front surface side electrode 25 and the back surface side electrode 26. ing. Since such a through electrode needs to be filled with the metal 24 in the through hole 22, it is difficult to form a through electrode having a small aspect ratio and a large aspect ratio. was there.

  Therefore, another example of forming a through electrode having a large aspect ratio will be described. This type of through electrode is formed as follows. First, a substrate 21 made of silicon is prepared, and a trench groove 27 having a circular planar shape, for example, is formed so as to surround a through electrode formation scheduled region (FIG. 6). The trench groove 27 has a structure in which the silicon substrate 21 a surrounded by the trench groove 27 is supported by the silicon substrate 21 that does not penetrate the silicon substrate 21 and remains below the trench groove 27.

  Thereafter, thermal oxidation is performed to fill the trench groove 27 with an insulating material. The silicon exposed to the inner wall surface of the trench groove 27 is oxidized by this thermal oxidation, and the trench groove 27 is filled with a silicon oxide film 28 of an insulating material (FIG. 7). A part of the silicon substrate surrounded by the trench groove 21 has a structure supported also by the silicon oxide film 28. The insulating material filled in the trench groove 27 may be an insulating material formed by, for example, a CVD method in addition to the silicon oxide film.

  The back surface side of the silicon substrate 21 is polished to expose the back surface side of the trench groove 27. By forming a front side electrode and a back side electrode (not shown) on the front side and the back side of the silicon substrate 21a surrounded by the silicon oxide film 28, it can be used as a through electrode (FIG. 8) (Patent Document 2). reference). Since the through electrode having such a structure does not need to fill the through hole with a metal, a through electrode having a large aspect ratio can be formed.

JP 2011-119750 A Japanese Patent No. 4944605

  As described above, a through electrode having a large aspect ratio can be formed by using a part of the silicon substrate as the through electrode. However, when the deep trench groove 27 is oxidized in this way, the silicon oxide film 28 is sufficiently filled on the front surface side, but the thickness of the silicon oxide film 28 is thin and the cavity remains in the vicinity of the bottom surface of the trench groove 27. End up. When the back side of the silicon substrate 21 is polished in such a state, there is a problem that stress is applied to the separated silicon substrate 21a, the silicon oxide film 28 is damaged, and an insulation failure occurs. In addition, since a polishing step is required, there is a problem that the manufacturing cost is increased.

  An object of this invention is to provide the manufacturing method which can eliminate the said problem and can manufacture a penetration electrode simply.

  In order to achieve the above object, an invention according to claim 1 of the present application includes a separation region penetrating a substrate, wherein the part of the substrate surrounded by the separation region is a through electrode. A step of preparing a substrate, a step of forming a plurality of through holes separated by leaving a part of the substrate in the separation region formation scheduled region, and at least the inside of the through hole and between the adjacent through holes A step of thermally oxidizing a part of the substrate to fill the through hole with an insulating material containing an oxide of the substrate and oxidizing a part of the substrate remaining between the through holes to form the isolation region; , Including.

  The invention according to claim 2 of the present application is the method for manufacturing an electronic device according to claim 1, wherein an extension is added to an end of the through hole, and the extension is adjacent to the through hole or an extension of the adjacent through hole. A portion of the substrate remaining between the step of forming the plurality of through-holes and the extension and the adjacent through-hole or the extension of the adjacent through-hole is thermally oxidized so as to be opposed to Forming the isolation region.

  The invention according to claim 3 of the present application is the method of manufacturing an electronic device according to claim 1 or 2, wherein the substrate is made of silicon.

  According to the manufacturing method of the present invention, when forming the isolation region, by forming a plurality of through holes separated by leaving a part of the substrate, a substrate that becomes a through electrode can be formed as a through hole instead of a trench groove. It becomes possible to support. For this reason, the inside of the through hole can be thermally oxidized from both the opening on the front side and the back side of the substrate, the thermal oxidation proceeds from the front side and the back side of the substrate, and the inside of the through hole can be filled with a thick oxide. As a result, sufficient insulation can be ensured between the through electrode and the surrounding substrate.

  In addition, the substrate remaining between adjacent through holes can be easily insulated by ordinary thermal oxidation, and sufficient insulation can be ensured between the through electrode and the surrounding substrate.

  Further, according to the manufacturing method of the present invention, the structure is provided with an extension at the end of the through hole, and is disposed so as to oppose the adjacent through hole or the extension of the adjacent through hole. The substrate can be reliably changed to an oxide, and a separation region between the through electrode and the surrounding substrate can be reliably formed.

It is explanatory drawing of the manufacturing method of the 1st Example of this invention. It is explanatory drawing of the manufacturing method of the 1st Example of this invention. It is explanatory drawing of the manufacturing method of the 1st Example of this invention. It is explanatory drawing of the manufacturing method of the 2nd Example of this invention. It is explanatory drawing of the conventional penetration electrode. It is explanatory drawing of the manufacturing method of another conventional penetration electrode. It is explanatory drawing of the manufacturing method of another conventional penetration electrode. It is explanatory drawing of the manufacturing method of another conventional penetration electrode.

  In the method for manufacturing an electronic device according to the present invention, when forming a separation region that insulates a through electrode made of a substrate from a surrounding substrate, a plurality of through holes are formed in the separation region formation scheduled region and thermally oxidized, The inside of the through hole is filled with an oxide, and a part of the substrate left between the through electrodes is insulated. Furthermore, an extended portion is formed at the end of the through hole, and a part of the substrate left between the through electrodes is surely insulated. Hereinafter, examples will be described in detail.

  A first embodiment of the present invention will be described. First, a substrate 1 made of low-resistance single crystal silicon having a thickness of 420 μm and a resistivity of 0.001 to 0.01 Ω · cm is prepared. An etching mask is formed on the surface to open a separation region formation scheduled region (not shown), and the substrate 1 is deeply etched to form a through hole 2 serving as a separation region (FIG. 1).

  Here, in the present invention, as schematically shown in FIG. 2, the plurality of through holes 2 are formed so as to divide the separation region formation scheduled region. 2A shows a case where the separation region is circular and the through-hole 2 is separated into four pieces, and FIG. 2B shows a case where the separation region is rectangular and the through-hole 2 is separated into four pieces. Show. Since the through hole 2 is separated, the substrate 1a in the region surrounded by the through hole 2 is integrally supported via the substrate 1 outside the through hole 2 and the four substrates 1b. The structure is such that the substrate 1a does not leave below the figure.

  Thereafter, as described in the conventional example, thermal oxidation is performed in a state where the front surface side and the back surface side of the through hole 2 are opened. By this thermal oxidation, the inside of the through hole 2 is filled with a silicon oxide film. In the present invention, the substrate 1b remaining between the through hole 2 and another adjacent through hole 2 is also oxidized at the same time to form a continuous separation region 3. The substrate surrounded by the separation region 3 becomes a through electrode (FIG. 3). Note that the insulating material filled in the through hole 2 need not be only the oxide of the substrate, and there is no problem even if a step of embedding another insulating material by, for example, the CVD method is added.

  In the through electrode, a desired electronic device can be formed by forming a front-side electrode and a back-side electrode (not shown) according to a normal manufacturing process of the electronic device.

  As described above, the present invention is a method in which the through hole 2 is formed while leaving the substrate 1b, and then the continuous separation region 3 is formed by thermal oxidation. Therefore, the substrate 1 is not polished and the substrate is etched. The shape corresponding to FIG. 8 described above can be easily formed by only the process and the thermal oxidation process.

  Next, a second embodiment of the present invention will be described. In the first embodiment described above, as shown in FIG. 3, the generation of oxide proceeds from the end of the through hole 2 in the substrate remaining between the adjacent through holes 2 (substrate 1 b in FIG. 2). However, since it is integrated, there may be a constriction. This portion is made of an oxide of the substrate 1 and does not cause any problem in insulation even when the width is smaller than the width of the through hole 2. However, if a part of the substrate remains between the oxides, insulation cannot be ensured. Therefore, in order to ensure the insulation of the substrate 1b, a method of increasing the opposing width of the adjacent through holes 2 is adopted.

  Specifically, as shown in FIG. 4, an extension 5 is formed at the end of the through hole 2 so that no gap is formed between oxides formed by thermal oxidation of the substrate 1b. As shown in FIGS. 4A to 4C, the extension portion 5 is provided such that the extension portion 5 is provided at each end of the through hole 2 and the extension portion 5 adjacent to the extension portion 5 is opposed to the extension portion 5. Further, as shown in FIG. 4D, an extension 5 is provided only at the end of one through-hole 2 of the adjacent through-hole 2, and this extension 5 is opposed to the through-hole 2 without the extension. You may arrange. By configuring in this way, the width of the substrate 1b (width through which the through hole 2 faces) is increased, and the substrate 1b can be reliably filled with an oxide film.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. For example, the arrangement and number of the through holes 2, the shape of the extension, and the like can be variously changed. Further, the through electrode of the present invention is not limited to the through electrode formed on the substrate having the integrated circuit on the surface, but a part of the semiconductor substrate is removed to form a cavity, and another semiconductor is formed in the cavity. It can also be used as a lid of a semiconductor device having a structure that can accommodate the device. Furthermore, the substrate to be used is not limited to silicon, but silicon is preferable in that a normal manufacturing process of an electronic device can be applied.

1: Substrate, 2: Through hole, 3: Separation region, 4: Through electrode, 5: Extension part 21: Substrate, 22: Through hole, 23: Insulating film, 24: Metal, 25: Front side electrode, 26: Back side Side electrode, 27: trench groove, 28: silicon oxide film

Claims (3)

In a method for manufacturing an electronic device comprising a separation region penetrating a substrate, wherein a part of the substrate surrounded by the separation region is a through electrode,
Preparing the substrate;
Forming a plurality of through-holes separated by leaving a part of the substrate in the separation region formation planned region;
At least a part of the substrate remaining in the through hole and between the adjacent through holes is thermally oxidized to fill the through hole with an insulating material containing an oxide of the substrate and to remain between the through holes. And a step of forming a part of the substrate to form the isolation region. In the manufacturing method of the electronic device of Claim 1,
Adding an extension to the end of the through-hole, and forming the plurality of through-holes so as to face the adjacent through-hole or the extension of the adjacent through-hole; and
And a step of thermally oxidizing a part of the substrate remaining between the extension and the adjacent through hole or an extension of the adjacent through hole to form the isolation region. Manufacturing method. In the manufacturing method of the electronic device in any one of Claim 1 or 2,
The method of manufacturing an electronic device, wherein the substrate is made of silicon.

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