JP2009246189A - Method of manufacturing semiconductor substrate, semiconductor substrate, and piezoelectric device using semiconductor substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a through electrode forming process of reducing floating capacitance between a through electrode portion and a semiconductor substrate since the floating capacitance is in inverse proportion to the thickness of an insulating layer with respect to a method of manufacturing a semiconductor substrate having a through electrode, the semiconductor substrate, and a piezoelectric device using the semiconductor substrate. <P>SOLUTION: In a stage of forming a through microhole 4 by dry etching along a sacrificial layer 3 formed on the semiconductor substrate 1, at least one annular hole 5 is formed outside the through microhole 4. In a stage of forming an insulating layer into the through microhole 4 by the thermal oxidation, the insulating layer is formed which includes, in one body, an oxide film on a surface of the through microhole 4 and an oxide film filling the annular hole 5, and an oxide film filling a thin portion of the semiconductor substrate 1 between the through microhole 4 and annular hole 5. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a semiconductor substrate having a through electrode with reduced stray capacitance, a semiconductor substrate, and a piezoelectric device using the semiconductor substrate.

Generally, a through electrode is used as a wiring technique for a semiconductor substrate, and various forming methods and shapes are disclosed. For example, see Patent Document 1.
JP 2007-294821 A

  FIGS. 6A and 6B are main part cross-sectional views illustrating a conventional through electrode forming process. Hereinafter, a conventional through electrode forming process will be described with reference to FIGS. 6A and 6B.

First, (a) after forming the SiO ₂ film 2 on the Si semiconductor substrate 1 by thermal oxidation, (b) removing the SiO ₂ film 2 on the front side by etching, and then forming through-holes with a resist material such as a photosensitive resin. A sacrificial layer 3 for forming is formed.

  Next, (c) the Si semiconductor substrate 1 is processed by dry etching to form through-holes 4.

Next, (d) the sacrificial layer 3 is removed by O ₂ ashing, (e) thermal oxidation is performed, and an insulating layer (SiO ₂ film) 6 is formed on the front and back surfaces of the Si semiconductor substrate 1 and the through-holes 4. Form. At this time, the SiO ₂ film 2 and the insulating layer (SiO ₂ film) 6 on the back surface of the Si semiconductor substrate 1 are integrated.

  Next, (f) a metal film is formed on the front side of the Si semiconductor substrate 1 by sputtering, photolithography is performed, then Au or the like is plated, an electrode portion is formed in the through microhole 4, and the metal film Unnecessary portions are removed, and through electrodes 7 are formed.

Next, (g) photolithography is performed on the back side of the Si semiconductor substrate 1 to remove the SiO ₂ film 2 and the insulating layer (SiO ₂ film) 6 on the back side of the Si semiconductor substrate 1 facing the through electrode 7 by etching.

  Next, (h) a metal film is formed on the back surface by sputtering, photolithography and etching are performed, the back electrode 8 is provided on the back side, and the through electrode 7 is conducted.

  In a piezoelectric device using a semiconductor substrate having a through electrode, the stray capacitance between the through electrode and the semiconductor substrate is inversely proportional to the thickness of the insulating layer. The stray capacitance affects the characteristics of the piezoelectric element mounted on the semiconductor substrate.

  In a manufacturing method for forming a through electrode on a semiconductor substrate, a step of forming a sacrificial layer for forming a through micro hole on the semiconductor substrate by photolithography using a resist, and forming the through micro hole by dry etching along the sacrificial layer In the method of forming an insulating layer by thermal oxidation after forming through-holes in the forming step, the thickness of the insulating layer of the through-electrode cannot be increased so as to reduce the stray capacitance. Also, in the case of the method of forming an insulating layer by CVD, the thickness of the insulating layer on the Si substrate surface is thicker than the thickness of the insulating layer of the through electrode, so that the insulating layer of the through electrode is formed to a desired thickness The deformation of the Si semiconductor substrate due to the stress of the insulating layer becomes large.

  The present invention provides a method for manufacturing a semiconductor substrate having a through-hole electrode, whereby an insulating layer having a desired thickness can be formed in the through-electrode, whereby the stray capacitance can be reduced and insulation other than the through-electrode can be formed. To provide a method for manufacturing a semiconductor substrate, a semiconductor substrate, and a piezoelectric device using the semiconductor substrate, which can suppress the deformation of the semiconductor substrate due to the stress of the insulating layer because the thickness of the layer can be suppressed. Is an issue.

  In order to achieve the above object, a method of manufacturing a semiconductor substrate according to the present invention includes a step of forming a sacrificial layer on a semiconductor substrate by photolithography using a resist, and dry etching along the sacrificial layer. Forming a through microhole, forming the through microhole, forming an insulating layer on the surface of the semiconductor substrate including the through microhole by thermal oxidation, and filling the through microhole with metal. And forming a through-hole electrode, wherein at least one annular hole is formed outside the through-microhole in the step of forming the through-hole hole by dry etching along the sacrificial layer. In the step of forming an insulating layer by thermal oxidation in the through-microholes, an oxide film on the surface of the through-microholes and an oxide film filling the annular holes, and the through-microholes and the annular holes Of integrating the oxide film embedded in the thin portion of the semiconductor substrate, and forming an insulating layer.

  In order to achieve the above object, a method of manufacturing a semiconductor substrate according to the present invention includes a step of forming a sacrificial layer for forming a fine groove on a semiconductor substrate by photolithography using a resist, and dry etching along the sacrificial layer. Forming a fine groove; forming the fine groove and then forming an insulating layer on the surface of the semiconductor substrate including the fine groove by thermal oxidation; and filling the fine groove with metal to form a through electrode A method of manufacturing a semiconductor substrate, comprising: a step of polishing the back surface of the semiconductor substrate; a step of forming an insulating layer on the back surface of the semiconductor substrate; and a step of forming a metal film on the back surface and connecting to the electrodes. In the step of forming the fine groove by dry etching along the sacrificial layer, at least one annular groove is formed outside the through fine groove, and the fine groove is thermally oxidized. In the process of forming the insulating layer, the oxide film on the surface of the fine groove and the oxide film filling the annular groove and the oxide film buried in the thin part of the semiconductor substrate between the fine groove and the annular groove are integrated. An insulating layer is formed.

  In the method for manufacturing a semiconductor substrate of the present invention, the thickness of the insulating layer on the surface of the semiconductor substrate can be formed thinner than the thickness of the insulating layer of the through electrode.

  The semiconductor substrate of the present invention is manufactured by the above manufacturing method.

  The piezoelectric device of the present invention is characterized in that the piezoelectric element is vacuum-sealed by mounting the piezoelectric element on the surface of the semiconductor substrate and bonding another substrate to the semiconductor substrate.

  According to the semiconductor substrate manufacturing method of the present invention, a semiconductor substrate manufacturing method, a semiconductor substrate, and a piezoelectric device using the semiconductor substrate, which can form a floating electrode of the semiconductor substrate and a through electrode that suppresses deformation of the semiconductor substrate. Can be provided.

  The best embodiment of the present invention will be described with reference to the drawings.

  FIGS. 1-1 and 1-2 are cross-sectional views of relevant parts for explaining a through electrode forming process in the first embodiment. FIG. 2 is a perspective view for explaining through fine holes and annular holes in the first embodiment. Hereinafter, the manufacturing method of the semiconductor substrate of the present embodiment will be described with reference to FIGS. 1-1 and 1-2.

First, (a) the SiO ₂ film 2 is formed on the Si semiconductor substrate 1 by thermal oxidation, and (b) the SiO ₂ film 2 on the front side of the Si semiconductor substrate 1 is removed by etching, followed by a resist such as a photosensitive resin. The sacrificial layer 3 is formed of a material.

  Next, (c) the Si semiconductor substrate 1 is processed by dry etching to form through-holes 4 and annular holes 5. A thin portion 9 of the Si semiconductor substrate 1 is formed between the through minute hole 4 and the annular hole 5. See FIG.

Next, (d) the sacrificial layer 3 is removed by O ₂ ashing, and (e) the surface of the Si semiconductor substrate 1 including the surfaces of the through-holes 4 and the annular holes 5 is expanded to an oxide film by thermal oxidation. Then, an insulating layer (SiO ₂ film) 6 is formed. At this time, the SiO ₂ film 2 and the insulating layer (SiO ₂ film) 6 on the back surface of the Si semiconductor substrate 1 are integrated. Further, an oxide film is embedded in the thin portion 9 of the Si semiconductor substrate between the through microhole 4 and the annular hole 5, and the oxide film on the surface of the through microhole 4 and the oxide film filling the annular hole 5 are integrated. The insulating layer (SiO ₂ film) 6 is formed.

  Next, (f) a metal film is formed on the front side of the Si semiconductor substrate 1 by sputtering, and after photolithography, Au or the like is plated. After the plating, the metal film formed by sputtering at an unnecessary place is removed. Then, the through electrode 7 is formed.

Next, (g) photolithography is performed on the back side of the Si semiconductor substrate 1, and the SiO ₂ film 2 and the insulating layer (SiO ₂ film) 6 facing the through electrode 7 are removed by etching.

  Next, (h) a metal film is formed on the back surface by sputtering, photolithography and etching are performed, the back electrode 8 is provided on the back side of the Si semiconductor substrate 1, and the through electrode 7 is made conductive.

  FIGS. 4-1 and FIGS. 4-2 are principal part sectional drawings explaining the penetration electrode formation process in Example 2. FIGS. Hereinafter, the manufacturing method of the semiconductor substrate of the present embodiment will be described with reference to FIGS.

  First, (a) a sacrificial layer 13 is formed on the front side of the Si semiconductor substrate 11 with a resist material such as a photosensitive resin.

  Next, (b) the Si semiconductor substrate 11 is processed by dry etching to form the fine grooves 14 and the annular grooves 15. A thin portion 19 of the Si semiconductor substrate 11 is formed between the fine groove 14 and the annular groove 15.

Next, (c) the sacrificial layer is removed by O ₂ ashing, and (d) by thermal oxidation, the surface of the Si semiconductor substrate 11 including the surfaces of the fine grooves 14 and the annular grooves 15 is expanded and changed into an oxide film, An insulating layer (SiO ₂ film) 16 is formed. Further, an oxide film is buried in the thin portion 19 of the Si semiconductor substrate 11 between the fine groove 14 and the annular groove 15, and the oxide film on the surface of the fine groove 14 and the oxide film filling the annular groove 15 are integrated and insulated. A layer (SiO ₂ film) 16 is formed.

  Next, (e) a metal film is formed on the front side of the Si semiconductor substrate 11 by sputtering, photolithography is performed, and Au or the like is then plated. After the plating, the metal film formed by sputtering at an unnecessary place is removed. Then, the through electrode 17 is formed.

  Next, (f) the back surface of the Si semiconductor substrate 11 is polished to expose the through electrodes 17.

Next, (g) an insulating layer (SiO ₂ film) 12 is formed on the back side of the Si semiconductor substrate 11 by CVD or the like.

Next, (h) photolithography is performed on the back side of the Si semiconductor substrate 11 to remove the insulating layer (SiO ₂ film) 12 facing the through electrode 17.

  Next, (i) a metal film is formed on the back surface by sputtering, photolithography and etching are performed, a back electrode 18 is provided on the back side of the Si semiconductor substrate 11, and the through electrode 17 is made conductive.

  In the first embodiment and the second embodiment, an example in which one annular hole or annular groove is formed is shown. However, as shown in FIG. 3, a plurality of annular holes 5 (or annular grooves) surrounding the through hole 4 are shown. ) May be formed. By forming the plurality of annular holes, the insulating layer of the through electrode can be formed thicker, and the stray capacitance between the through electrode and the semiconductor substrate can be further reduced. FIG. 3 is a cross-sectional view of a main part in which two annular holes are formed outside the through-holes.

  FIG. 5 is a cross-sectional view of the piezoelectric device according to the third embodiment. Here, a piezoelectric device in which a piezoelectric element is hermetically sealed will be described as an example.

  A recess 21 is formed on one side of the Si semiconductor substrate 20 constituting the piezoelectric device 50 by photolithography and dry etching, and the insulating layer of the through electrode 22 is formed in the recess 21 by the semiconductor substrate manufacturing method as described above. A through electrode 22 having a thickness of about 2 to 3 μm is formed on the surface of the Si semiconductor substrate 20, which is thinner than the insulating layer of the through electrode 22.

  A piezoelectric element 30 is mounted on the electrode portion of the Si semiconductor substrate 20 on which the concave portion 21 is formed by using a conductive adhesive or the like, and then a substrate to be the lid 40 is joined to the Si semiconductor substrate 20. At this time, bonding is performed in a vacuum chamber so that the space in which the piezoelectric element 30 is mounted is in a vacuum state.

  Due to the reduction of the stray capacitance of the through electrode 22, the piezoelectric element 30 maintains stable oscillation characteristics. Furthermore, deformation due to stress of the insulating layer on the surface of the Si semiconductor substrate 20 can be suppressed.

Cross-sectional view of relevant parts for explaining a through electrode forming process in Example 1 Cross-sectional view of relevant parts for explaining a through electrode forming process in Example 1 The perspective view explaining the penetration fine hole and the annular hole in Example 1 Cross-sectional view of the main part in which two annular holes are formed outside the through-holes Cross-sectional view of relevant parts for explaining a through electrode forming process in Example 2 Cross-sectional view of relevant parts for explaining a through electrode forming process in Example 2 Sectional drawing of the piezoelectric device in Example 3 Cross-sectional view of relevant parts for explaining a conventional through electrode forming process Cross-sectional view of relevant parts for explaining a conventional through electrode forming process

Explanation of symbols

1 Si semiconductor substrate 2 SiO ₂ film 3 sacrificial layer 4 through micropores 5 annular hole 6 insulating layer (SiO ₂ film)
7 Through electrode 8 Back electrode 9 Thin portion 11 Si semiconductor substrate 12 Insulating layer (SiO ₂ film)
13 Sacrificial layer 14 Fine groove 15 Annular groove 16 Insulating layer (SiO ₂ film)
17 Through electrode 18 Back electrode 19 Thin portion 20 Si semiconductor substrate 21 Recess 22 Through electrode 30 Piezoelectric element 40 Lid 50 Piezoelectric device

Claims (5)

Forming a sacrificial layer for forming through-holes by photolithography on a semiconductor substrate with a resist;
Forming a through microhole by dry etching along the sacrificial layer;
Forming an insulating layer by thermal oxidation on the surface of the semiconductor substrate including the through micropores after forming the through micropores;
In the method of manufacturing a semiconductor substrate, including a step of forming a through electrode by filling the through fine hole with a metal,
Forming at least one annular hole outside the through microhole in the step of forming the through microhole by dry etching along the sacrificial layer;
In the step of forming an insulating layer by thermal oxidation in the through-microhole, an oxide film on the surface of the through-microhole and an oxide film filling the annular hole, and a thin portion of the semiconductor substrate between the through-microhole and the annular hole A method of manufacturing a semiconductor substrate, comprising forming an insulating layer integrated with an embedded oxide film. Forming a sacrificial layer for forming a fine groove by photolithography on a semiconductor substrate with a resist;
Forming a fine groove by dry etching along the sacrificial layer;
Forming the insulating layer by thermal oxidation on the surface of the semiconductor substrate including the fine groove after forming the fine groove;
Filling the fine groove with metal to form a through electrode, polishing the back surface of the semiconductor substrate, forming an insulating layer on the back surface of the semiconductor substrate, forming a metal film on the back surface, In a method of manufacturing a semiconductor substrate having a step of connecting to an electrode,
Forming a fine groove by dry etching along the sacrificial layer, forming at least one annular groove outside the through fine groove;
In the step of forming an insulating layer by thermal oxidation in the fine groove, the oxide film on the surface of the fine groove and the oxide film filling the annular groove, and the thin portion of the semiconductor substrate between the fine groove and the annular groove are buried. A method of manufacturing a semiconductor substrate, comprising forming an insulating layer integrated with an oxide film.   The method for manufacturing a semiconductor substrate according to claim 1, wherein a thickness of the insulating layer on the surface of the semiconductor substrate is formed to be thinner than a thickness of the insulating layer of the through electrode.   A semiconductor substrate manufactured by the method for manufacturing a semiconductor substrate according to claim 1. A piezoelectric device using the semiconductor substrate according to claim 4,
A piezoelectric device, wherein a piezoelectric element is mounted on the surface of the semiconductor substrate, and the piezoelectric element is vacuum-sealed by bonding another substrate to the semiconductor substrate.

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