JP2011066251A - Method of manufacturing semiconductor substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a semiconductor substrate, capable of achieving a high quality through type electrode in higher productivity at lower cost, even when the semiconductor substrate is thick. <P>SOLUTION: An electrode pad (102) having an opening (104) including an exposed active surface is formed to a semiconductor substrate (101). A recess (105a) is formed toward the surface in the opposite side of the active surface from the opening (104). An insulating film (106) is formed at the internal side of the recess (105a). A conductive path (107) is formed on the surface of the insulating film (106) and the electrode pad (102). Thereafter, the semiconductor substrate (101) is formed thinner from the surface in the opposite side of the active surface and is then provided through the bottom of the recess (105a). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a semiconductor substrate having a through electrode.

  When a semiconductor is mounted on a semiconductor substrate and packaged, a small and low-profile packaging is realized by forming a through electrode in the semiconductor substrate. As a conventional method for forming a through electrode, there is one described in Patent Document 1 or the like.

FIG. 7 shows the through electrode forming method of Patent Document 1.
In some cases, a through-hole and a conduction path are formed from the side opposite to the active surface on which elements of the semiconductor substrate are formed toward the active surface. 11 is a semiconductor substrate, 12 is a first silicon oxide film, 13 is a pore, 14 is a second silicon oxide film on the wall, 15 is a metal thin film, 16 is a second metal thin film, and 17 is a through electrode. .

In FIG. 7A, a first silicon oxide film 12a is formed on the active surface of the semiconductor substrate 11, and a first silicon oxide film 12b is formed on the opposite side of the active surface.
In FIG. 7B, a pattern is formed on a part of the first silicon oxide film 12b by photolithography, and then removed by dry etching.

In FIG. 7C, after forming a pattern by photolithography, the pores 13 are formed in the semiconductor substrate 11 by dry etching.
In FIG. 7D, the side surfaces of the pores 13 are insulated with the second silicon oxide film 14.

In FIG. 7E, the metal thin film 15 and the second metal thin film 16 are formed on the active surface of the semiconductor substrate 11 so as to overlap each other.
In FIG. 7F, the first silicon oxide film 12a on the active surface side is removed by dry etching through the pores 13.

  In FIG. 7G, the through electrode 17 is formed by filling the pores 13 with a conductive material so as to be electrically connected to the metal thin film 15.

JP 2004-94859 A

  However, in the conventional configuration, since the through-hole is formed from the surface opposite to the active surface of the semiconductor substrate 11, the thin film 12a on the active surface in FIG. There is a problem that it may be broken by thermal stress.

  Further, when the semiconductor substrate 11 is thick, a typical processing speed is 15 μm / min in the formation of the through hole. For example, when the semiconductor substrate is 300 μm, it takes 20 min, and the productivity is low. is doing.

  An object of the present invention is to provide a method of manufacturing a semiconductor substrate that can realize a through electrode with high productivity, high quality, and low cost even when the semiconductor substrate is thick.

  According to the method of manufacturing a semiconductor substrate of the present invention, an electrode pad having an opening through which an active surface of the semiconductor substrate is exposed is formed on the semiconductor substrate, and the semiconductor substrate is directed from the opening to the opposite surface from the active surface. Forming a recess that does not reach the opposite surface, forming an insulating film inside the recess, forming a conductive path on the surface of the insulating film and the electrode pad, and removing the semiconductor substrate from the opposite surface The semiconductor substrate is thinned so that the bottom of the recess penetrates the opposite surface. The concave portion is formed by any of dry etching, blasting, and laser processing. Moreover, it is preferable to form the shape of the said recessed part in the depth direction in a taper shape.

  The method of manufacturing a semiconductor substrate according to the present invention includes forming an electrode pad having an opening through which an active surface of the semiconductor substrate is exposed on the semiconductor substrate, thinning the semiconductor substrate from a surface opposite to the active surface, A hole penetrating the opposite surface from the active surface to the opposite surface is formed in the semiconductor substrate from the opening, an insulating film is formed inside the hole, and the insulating film and the electrode pad A conductive film is formed on the surface. The holes are formed in the semiconductor substrate by any of dry etching, blasting, and laser processing methods. It is preferable to form the hole in a tapered shape.

  The semiconductor substrate of the present invention is formed by penetrating an electrode pad having an opening through which an active surface of the semiconductor substrate is exposed in the semiconductor substrate and a surface opposite to the active surface of the semiconductor substrate exposed by the opening. An insulating film formed on the active surface of the semiconductor substrate exposed by the inside of the through hole and the opening, an electrode pad surface, and an end formed on the surface of the insulating film. A conductive path exposed on the opposite surface of the substrate is provided.

  According to another aspect of the present invention, there is provided a semiconductor substrate including an electrode pad having an opening through which an active surface of the semiconductor substrate is exposed, and a surface opposite to the active surface of the semiconductor substrate exposed through the opening. A through hole formed on the active surface of the semiconductor substrate that is exposed by the opening and the inside of the through hole and the opening, the opening of the active surface of the semiconductor substrate being larger than the opening of the opposite surface; And a conductive path formed on the surface of the electrode pad and the surface of the insulating film and having an end exposed on the opposite surface of the semiconductor substrate. It is preferable that the horizontal cross section inside the through hole has irregularities. It is preferable that a cross section of the through hole is circular, and a ratio of a diameter of an opening on the active surface of the through hole and an opening on the opposite surface is 0.5 or more and 0.8 or less.

  According to this configuration, it is possible to form a through electrode from the active surface of the semiconductor substrate, and it is possible to avoid the conventional problems that the thin film on the active surface is over-etched due to process processing or is destroyed by thermal stress, and laser processing The process can be used, and the cost for forming the through electrode can be reduced.

  Further, by reducing the thickness of the semiconductor substrate from the surface opposite to the active surface, there is an effect of improving productivity as compared with the conventional case.

The enlarged plan view of the semiconductor substrate of Embodiment 1 of this invention, and its AA sectional drawing It is explanatory drawing of the manufacturing process of the embodiment, The left side is a top view of the semiconductor substrate in each process, The right side is an expanded sectional view FIG. 8 is an explanatory diagram of the manufacturing process of the semiconductor substrate according to the second embodiment of the present invention, the left side is a plan view of the semiconductor substrate in each step, and the right side is an enlarged cross-sectional view. The enlarged plan view of the semiconductor substrate of Embodiment 3 of this invention, and its AA sectional drawing In the explanatory view of the manufacturing process of the semiconductor substrate of the embodiment, the left side is a plan view of the semiconductor substrate in each step, the right side is an enlarged sectional view The enlarged plan view of the semiconductor substrate of Embodiment 4 of this invention, and its AA sectional drawing Process flow diagram of conventional through electrode forming method described in Patent Document 1

Hereinafter, each embodiment of the present invention will be described with reference to FIGS.
(Embodiment 1)
1 and 2 show Embodiment 1 of the present invention.

  FIG. 1 is an enlarged plan view of a semiconductor substrate on which a through electrode is formed, and an AA cross-sectional view thereof. This semiconductor substrate is produced by the process shown in FIG. 2A to 2E show a plan view on the left side and an enlarged cross-sectional view on the right side.

In FIG. 2A, an electrode having an opening 104 is formed on a semiconductor substrate 101 formed of a material such as Si, SiC, or GaAs. The semiconductor substrate 101 has a size of φ3 inch to φ12 inch and a thickness of about 0.2 mm to 0.7 mm. Specifically, an opening 104 for exposing the semiconductor substrate 101 is formed in the oxide film 103 formed on the semiconductor substrate 101 and the electrode pad 102 formed on the oxide film 103. The oxide film 103 is made of SiO ₂ or the like and has a thickness of about 0.1 μm to 1 μm. The electrode pad 102 is made of Al, Al-Cu, etc., and has a size of 50 to 100 squares and a thickness of 0.3 mm to 1 mm.

  A structure in which the electrode pad 102 on the oxide film 103 does not exist partially can be formed by patterning the oxide film using photolithography in a semiconductor IC processing process. Further, the opening 104 can be realized without an additional process by designing a mask when the electrode pad 102 is patterned. The opening 104 is circular and its size is about 10 to 20% smaller than the size of the electrode pad 102. For example, when the electrode pad 102 is 100 μm, the diameter may be 80 μm to 90 μm at the center.

In FIG. 2B, a recess 105 a having a diameter of 50 μm to 100 μm is formed on the semiconductor substrate 101 inside the opening 104.
The recess 105a is processed by masking a design to be processed with a resist having a thickness of 20 μm to 30 μm using a photolithographic process, and processing a portion opened by dry etching, blasting, or laser. Here, the recess 105 a is formed partway so as not to penetrate the thickness of the semiconductor substrate 101.

In FIG. 2C, an insulating film 106 such as SiO ₂ having a thickness of about 1 μm to 5 μm is formed on the surface of the semiconductor substrate 101 inside the inner peripheral surface of the recess 105 a and the opening 104. This insulating film 106 is for preventing a leakage due to an electrical short circuit between a conductive path 107 and a semiconductor substrate 101 to be formed later. Oxide film formation using a CVD process in a state where the surface of the electrode pad 102 is masked by a photolithographic process so that the insulating film 106 is not formed on the surface of the electrode pad 102, or a printing method such as ink jet or spraying an insulating material Form with.

  In FIG. 2D, a conductive path 107 is formed of a conductive material on the insulating film 106 and the electrode pad 102. Specifically, a Ti / Cu sputtering or vapor deposition film of about 0.1 μm to 0.3 μm is formed on the insulating film 106, and then a thickness of about 5 μm to 10 μm is secured by electrolysis or electroless Cu plating. . The conductive path 107 can also be formed by filling a conductive paste with an ink jet or printing method.

  In FIG. 2E, polishing is performed from the back surface side of the active surface in order to control the surface roughness of the back surface of the semiconductor substrate 101. Thereby, a through electrode having a conductive path penetrating from the front of the semiconductor substrate 101 to the back of the semiconductor substrate 101 can be formed. Thereafter, an insulating film and a wiring pattern are formed on the back surface side of the semiconductor substrate 101, and a process such as forming a BGA electrode so as to be mounted on the substrate is performed. In addition, the through-hole formed by the recessed part 105a was illustrated as 105aa in FIG.

  According to such a configuration, the through electrode can be formed from the active surface without changing the process only by changing the design of the wafer, and can be carried out without increasing the cost.

  Then, as in the case where the semiconductor substrate 101 is formed from the surface opposite to the active surface, the thin film on the active surface is not over-etched by the process process and is not destroyed by defects or thermal stress.

  Further, when the semiconductor substrate 101 is thick, a typical processing speed is 15 μm / min in the formation of the through hole. For example, when the semiconductor substrate 101 is 300 μm, it takes 20 minutes and the productivity is low. On the other hand, by forming a through electrode from the active surface and performing a process of polishing and thinning the semiconductor substrate 101 from the back side after forming the through electrode, there is an effect of improving productivity.

  In addition, since there is no problem in the process of causing a thermal change in the electrode pad 102 as in laser processing, the laser processing process can be used, and the cost for forming the through electrode can be reduced.

  In the case of drilling from the surface opposite to the active surface of the semiconductor substrate 101, it is necessary to process the oxide film after drilling Si. According to the method utilizing this structure, since the oxide film is not present in the hole processing portion, the oxide film processing process can be eliminated, quality deterioration due to process yield can be prevented, and processing cost can be reduced.

(Embodiment 2)
FIG. 3 shows a second embodiment of the present invention.
In the first embodiment, the semiconductor substrate 101 is polished and thinned in the final FIG. 2E, but in the process shown in FIG. 3, the semiconductor substrate 101 is polished between FIG. 2A and FIG. The difference is that it is thinned.

  In FIG. 3A, an electrode having an opening 104 is formed on a semiconductor substrate 101 formed of a material such as Si, SiC, or GaAs. An opening 104 for exposing the semiconductor substrate 101 is formed in the oxide film 103 formed on the semiconductor substrate 101 and the electrode pad 102 formed on the oxide film 103.

In FIG. 3B, the semiconductor substrate 101 is cut to an arbitrary thickness using a grinder or the like from the back surface side.
In FIG. 3C, a hole 105 b having a diameter of 50 μm to φ100 μm penetrating on the back surface side of the semiconductor substrate 101 is formed on the semiconductor substrate 101 inside the opening 104.

In FIG. 3D, an insulating film 106 such as SiO ₂ having a thickness of about 1 μm to 5 μm is formed on the surface of the semiconductor substrate 101 inside the hole 105 b and inside the opening 104. Oxide film formation using a CVD process in a state where the surface of the electrode pad 102 is masked by a photolithographic process so that the insulating film 106 is not formed on the surface of the electrode pad 102, or a printing method such as ink jet or spraying an insulating material Form with.

  In FIG. 3E, a conductive path 107 is formed of a conductive material on the insulating film 106 and the electrode pad 102. Thereby, a through electrode having a conductive path penetrating from the front surface of the semiconductor substrate 101 to the back surface of the semiconductor substrate 101 can be formed. Thereafter, an insulating film and a wiring pattern are formed on the back surface side of the semiconductor substrate 101, and a process such as forming a BGA electrode so as to be mounted on the substrate is performed.

  According to this configuration, by controlling the thickness of the semiconductor substrate 101 to be thin before the hole 105b is processed, the man-hours required for the hole processing can be performed only to the minimum necessary conditions, so there is no waste and an extra cost increases. Disappears.

(Embodiment 3)
4 and 5 show Embodiment 3 of the present invention.
In the first embodiment, the shape of the recess 105a formed in the semiconductor substrate 101 in FIG. 2B is a single circle from the opening on the active side of the semiconductor substrate 101 toward the bottom, but in the third embodiment, As shown in FIGS. 4A and 4B, the shape of the recess 105a is different in that the diameter gradually decreases from the opening on the active side of the semiconductor substrate 101 toward the bottom.

In FIG. 5A, an electrode having an opening 104 is formed on a semiconductor substrate 101 formed of a material such as Si, SiC, or GaAs. Specifically, an opening 104 for exposing the semiconductor substrate 101 is formed in the oxide film 103 formed on the semiconductor substrate 101 and the electrode pad 102 formed on the oxide film 103. The oxide film 103 is made of SiO ₂ or the like and has a thickness of about 0.1 μm to 1 μm. The electrode pad 102 is made of Al, Al-Cu, etc., and has a size of 50 to 100 squares and a thickness of 0.3 mm to 1 mm.

  A structure in which the electrode pad 102 on the oxide film 103 does not exist partially can be formed by patterning the oxide film using photolithography in a semiconductor IC processing process. Further, the opening 104 can be realized without an additional process by designing a mask when the electrode pad 102 is patterned. The opening 104 is circular and its size is about 10 to 20% smaller than the size of the electrode pad 102. For example, when the electrode pad 102 is 100 μm, the diameter may be 80 μm to 90 μm at the center.

  In FIG. 5B, a tapered recess 105c having an angle of 60 ° to 85 ° is formed on the semiconductor substrate 101 inside the opening 104 by a method such as dry etching, laser, or blasting. Here, the recess 105 c is formed partway so as not to penetrate the thickness of the semiconductor substrate 101.

In FIG. 5C, an insulating film 106 such as SiO ₂ having a thickness of about 1 μm to 5 μm is formed on the surface of the semiconductor substrate 101 inside the inner peripheral surface of the recess 105 c and the opening 104. This insulating film 106 is for preventing a leakage due to an electrical short circuit between a conductive path 107 and a semiconductor substrate 101 to be formed later. Oxide film formation using a CVD process in a state where the surface of the electrode pad 102 is masked by a photolithographic process so that the insulating film 106 is not formed on the surface of the electrode pad 102, or a printing method such as ink jet or spraying an insulating material Form with.

In FIG. 5D, a conductive path 107 is formed of a conductive material on the insulating film 106 and the electrode pad 102.
In FIG. 5E, polishing is performed from the back surface side of the active surface in order to control the surface roughness of the back surface of the semiconductor substrate 101. Thereby, a through electrode having a conductive path penetrating from the front of the semiconductor substrate 101 to the back of the semiconductor substrate 101 can be formed. Thereafter, an insulating film and a wiring pattern are formed on the back surface side of the semiconductor substrate 101, and a process such as forming a BGA electrode so as to be mounted on the substrate is performed. The tapered through hole formed by the recess 105c is shown as 105cc in FIG.

  According to this configuration, by forming the through hole in a tapered shape, sputtering and plating can be facilitated, quality deterioration due to yield loss can be reduced, and cost can be suppressed. The ratio of the diameter of the opening on the upper surface of the tapered through hole to the diameter of the opening on the lower surface is preferably 0.8 to 0.5. At 0.5, the lower surface diameter is half of the upper surface diameter. If it is less than that, continuity cannot be obtained due to misalignment in the case of connection. When the ratio is 0.8 or more, it is difficult to form a film, and in particular, it is difficult to form a film at an edge portion.

(Embodiment 4)
FIG. 6 shows a fourth embodiment of the present invention.
In each of the above embodiments, the horizontal cross-sectional shape of the through electrode formed on the semiconductor substrate 101 is circular. However, in this fourth embodiment, as shown in FIGS. The difference is that the horizontal cross-sectional shape of the electrode is a star.

This through-hole electrode having a star-shaped horizontal cross section is formed by forming a mask with a resist or the like in the region of the opening 104 where the semiconductor substrate 101 is exposed with respect to the electrode pad 102, and performing dry etching, laser, blasting, etc. After forming a star-shaped recess 105a having a horizontal cross-sectional shape on the semiconductor substrate 101 by the method, and forming an oxide film 103 such as SiO _{2 on} the surface of the star-shaped recess 105a, Ti sputtering, vapor deposition, Cu plating is formed thereon. The conductive path 107 is formed by, for example. Note that the tapered through hole formed by the recess 105a is illustrated as 105ab in FIG.

According to such a configuration, by making the through-hole shape into a star shape, the surface area of the side surface is increased, and the via resistance is reduced and the heat dissipation is improved.
In this embodiment, the case where the star-shaped concave portion 105a is formed has been described as an example. However, the present invention can be similarly implemented when the planar shape of the hole 105b shown in FIG.

  In addition, although the case where the horizontal cross-sectional shape of the through electrode is a star has been described as an example, the same effect can be obtained with other polygons such as an uneven circle, a gear shape, and an uneven square. Further, they can be formed in a tapered shape as in the third embodiment.

  In each of the above embodiments, the case where one through electrode is formed for one electrode pad has been described as an example, but the same applies to the case where a plurality of through electrodes are formed for one electrode pad. is there.

  The present invention can realize downsizing, thinning, cost reduction, and high-speed signal transmission of semiconductor packaging, and can contribute widely to the development of electronic devices.

101 Semiconductor substrate 104 Opening 103 Oxide film 102 Electrode pad 105a Recess 106 Insulating film 107 Conductive path 105aa Through hole 105b Hole 105c Tapered recess 105cc Through hole 105ab Through hole

Claims (10)

Forming an electrode pad on the semiconductor substrate having an opening through which the active surface of the semiconductor substrate is exposed;
Forming a recess that does not reach the opposite surface from the active surface to the opposite surface from the opening to the semiconductor substrate;
Forming an insulating film inside the recess,
Forming a conductive path on the surface of the insulating film and the electrode pad;
A method of manufacturing a semiconductor substrate, wherein the semiconductor substrate is thinned from the opposite surface and the bottom of the concave portion is penetrated through the opposite surface. The method of manufacturing a semiconductor substrate according to claim 1, wherein the recess is formed by any one of dry etching, blasting, and laser processing. The method of manufacturing a semiconductor substrate according to claim 1, wherein a shape of the concave portion in a depth direction is formed in a tapered shape. Forming an electrode pad on the semiconductor substrate having an opening through which the active surface of the semiconductor substrate is exposed;
Thinning the semiconductor substrate from the surface opposite to the active surface,
Forming a hole penetrating from the opening to the opposite surface toward the opposite surface from the active surface to the semiconductor substrate;
Forming an insulating film inside the hole;
A method of manufacturing a semiconductor substrate, wherein a conductive path is formed on surfaces of the insulating film and the electrode pad. The method of manufacturing a semiconductor substrate according to claim 1, wherein the hole is formed in the semiconductor substrate by any one of dry etching, blasting, and laser processing.   The method for manufacturing a semiconductor substrate according to claim 4, wherein the hole is formed in a tapered shape. An electrode pad having an opening exposing an active surface of the semiconductor substrate on the semiconductor substrate;
A through-hole formed through the surface opposite to the active surface of the semiconductor substrate exposed by the opening;
An insulating film formed on the active surface of the semiconductor substrate exposed by the inside of the through hole and the opening;
A semiconductor substrate provided with a surface of an electrode pad and a conductive path formed on the surface of the insulating film and having an end exposed on the opposite surface of the semiconductor substrate. An electrode pad having an opening exposing an active surface of the semiconductor substrate on the semiconductor substrate;
A through hole formed by penetrating from the active surface of the semiconductor substrate exposed by the opening to the opposite surface, the opening of the active surface of the semiconductor substrate being larger than the opening of the opposite surface;
An insulating film formed on the active surface of the semiconductor substrate exposed by the inside of the through hole and the opening;
A semiconductor substrate provided with a surface of an electrode pad and a conductive path formed on the surface of the insulating film and having an end exposed on the opposite surface of the semiconductor substrate.   The semiconductor substrate according to claim 7, wherein the horizontal cross section inside the through hole has irregularities.   The cross section of the through hole is circular, and a ratio of a diameter of the opening on the active surface of the through hole and the opening on the opposite surface is 0.5 or more and 0.8 or less. Semiconductor substrate.

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