JP6076114B2 - Semiconductor device, solid-state imaging device, and manufacturing method of semiconductor device - Google Patents

Description

  The present invention relates to a semiconductor device, and more particularly to a stacked semiconductor device in which a large number of electrodes are formed on a substrate, a solid-state imaging device, and a method for manufacturing the semiconductor device.

  In order to increase the functionality and miniaturization of the system, a smaller and higher performance semiconductor device is required, and a stacked semiconductor device configured by bonding wafers on which a large number of minute electrodes are formed has been studied. Yes.

  In stacked semiconductor devices, the semiconductor substrates are connected by electrodes, but simply connecting the electrodes is vulnerable to external forces and stresses, and also causes corrosion of the electrodes due to humidity and temperature. A portion other than the electrodes between the semiconductor substrates may be sealed with a resin called fill. Sealing with underfill is usually performed by injecting underfill from the gap between the semiconductor substrates after connecting the electrodes, but injection after connection due to the recent narrowing of the pitch of electrodes and concomitant narrowing of the gap. It's getting harder to do.

Therefore, in recent years, attention has been paid to a method in which an underfill is applied to a semiconductor substrate before connecting the electrodes and then the connection is performed.
In relation to this method, Patent Document 1 describes a method in which an underfill is applied on one semiconductor substrate on which an electrode is formed, and the electrode of the other semiconductor substrate is pressed against the one semiconductor substrate. Has been. Due to the pressure contact, the electrodes of the other semiconductor substrate approach one semiconductor substrate while pushing the underfill, and the electrodes come into contact with each other to conduct the semiconductor substrate.

JP 2009-203292 A

  However, in the method described in Patent Document 1, there is a possibility that an underfill may remain between the end faces of the two electrodes, and if the underfill remains, there is a problem that it causes a bonding failure of the electrodes.

In view of the above circumstances, an object of the present invention is to provide a semiconductor device having a structure in which electrodes can be reliably bonded to each other even when an underfill is applied before the electrodes are bonded, and a manufacturing method thereof.
Another object of the present invention is to provide a solid-state imaging device having a high mounting strength in which a large number of electrodes are provided but they are securely connected.

  A first aspect of the present invention is a semiconductor device comprising a first semiconductor substrate and a second semiconductor substrate bonded to the first semiconductor substrate, wherein the first semiconductor substrate and the second semiconductor substrate An underfill layer formed between the first semiconductor substrate and the first semiconductor substrate, the first semiconductor substrate having a concave portion provided on one surface and a first electrode disposed in the concave portion, The second semiconductor substrate has a second electrode shaped so that at least a part thereof can enter the recess, and the second electrode penetrates the underfill layer and pierces the first electrode. One electrode is connected to the second electrode.

  A second aspect of the present invention is a solid-state imaging device including the semiconductor device of the present invention.

According to a third aspect of the present invention, there is provided a first substrate forming step of forming a first semiconductor substrate having a recess provided on one surface and a first electrode disposed in the recess, and at least partly A second substrate forming step of forming a second semiconductor substrate having a second electrode having a shape capable of entering the recess, and applying an underfill on the one surface of the first semiconductor substrate. An underfill layer forming step of forming an underfill layer, the second electrode facing the one surface, the first semiconductor substrate and the second semiconductor substrate are contacted, and the second electrode is A pressure bonding step of bonding the first semiconductor substrate and the second semiconductor substrate by applying pressure so as to penetrate the first electrode through the underfill layer. It is a manufacturing method .

According to the semiconductor substrate and the manufacturing method thereof of the present invention, the electrodes can be reliably bonded even if the underfill is applied before the electrodes are bonded.
In addition, according to the solid-state imaging device of the present invention, although a large number of electrodes are provided, these can be reliably connected and the mounting strength can be increased.

The upper side is a plan view showing a semiconductor substrate used for manufacturing a semiconductor device according to an embodiment of the present invention, and the lower side is a diagram showing an operation of bonding the semiconductor substrate. (A) is a figure which shows the process of individualization, (b) is a perspective view which shows one unit area | region cut out as a semiconductor device. FIG. 4 is an enlarged cross-sectional view showing a joint portion between a first semiconductor substrate and a second semiconductor substrate in the semiconductor device. It is a figure which shows one process in the manufacturing method of the same semiconductor device.

An embodiment of the present invention will be described with reference to FIGS. The semiconductor device of the present invention is a stacked semiconductor device formed by bonding a plurality of semiconductor substrates on which circuits, wirings, and the like are formed.
The upper side of FIG. 1 is a plan view showing a basic configuration of a semiconductor substrate 1 used for manufacturing the semiconductor device of the present embodiment. As shown in FIG. 1, the semiconductor substrate 1 includes a plate-like or sheet-like base material 10 and a plurality of electrode arrays 20 formed on the surface of the base material 10.

The base material 10 is an insulator or a semiconductor and is formed in a plate shape or a sheet shape having a predetermined thickness. As an insulator and a semiconductor which comprise the base material 10, silicon | silicone, resin, ceramics, glass etc. are mentioned, for example. In the present embodiment, a silicon wafer is used as the base material 10.
Although not shown, the base material 10 is formed with wirings electrically connected to the electrode array 20. The wiring mode may be formed on one or both surfaces in the thickness direction of the substrate 10 by printing, etching, or the like, or may be formed so as to penetrate the substrate, such as a via. Furthermore, it may be a three-dimensional wiring using a lamination technique, and these may be combined as appropriate. Further, a circuit, a semiconductor element, or the like that exhibits a predetermined function may be formed by wiring, or a semiconductor element may be attached to the base material 10.

  One surface of the base material 10 is a bonding surface 10A that is bonded to another semiconductor substrate. A plurality of rectangular unit regions 11 are provided on the bonding surface 10A, and one electrode array 20 in which a plurality of electrodes are formed in the same layout is formed in each unit region 11 to form wirings in the same mode. Has been.

In the semiconductor device of this embodiment, the semiconductor substrate 1 and the counterpart semiconductor substrate 101 are sandwiched between the pressure plates 131 and 132 with the bonding surface 10A facing the counterpart substrate, as shown in the lower side of FIG. It is manufactured by joining together by pressurizing and heating using a press apparatus (not shown) and joining the semiconductor substrate 1 and the counterpart substrate while being electrically connected. Prior to this bonding, the surfaces and electrode portions of both substrates may be cleaned by plasma cleaning, reverse sputtering, or the like, and the electrodes may be bonded using so-called surface activation. At this time, it is preferable to perform bonding in a vacuum atmosphere or a nitrogen atmosphere.
In the following description, the semiconductor substrate 1 is referred to as the first semiconductor substrate 1 and the counterpart semiconductor substrate 101 is referred to as the second semiconductor substrate 101.

  After the substrates are joined, as shown in FIG. 2A, the joined substrate is cut out into individual unit regions 11 along the boundary line 12 of the unit regions with a blade 110 or the like (divided into individual pieces). As shown in (b), the semiconductor device 120 of this embodiment is completed. In the semiconductor device 120, the first semiconductor substrate 1 and the second semiconductor substrate 101 are sealed with an underfill layer 31 made of resin.

FIG. 3 is an enlarged cross-sectional view illustrating a bonding portion between the first semiconductor substrate 1 and the second semiconductor substrate 101 in the semiconductor device 120.
As shown in FIG. 3, a plurality of recesses 51 are formed on the bonding surface 10 </ b> A of the first semiconductor substrate 1, and a part of wiring or a circuit (hereinafter referred to as “wiring or the like”) is formed on the bottom surface of the recess 51. Is exposed). The exposed wiring or the like may be formed in a pad shape to increase the area.
In the recess 51, a first electrode 52 filled with a conductive material and electrically connected to the exposed wiring or the like is formed. The material for forming the first electrode 52 is not particularly limited as long as the material can be adjusted to such a degree that the second electrode (described later) of the second semiconductor substrate 101 is pierced. For example, solder or indium (In A relatively soft metal such as) or a conductive resin can be used. Moreover, you may form the 1st electrode 52 so that it may take a porous structure which has a fine space | gap inside using a general metal material. Examples of a method for forming an electrode having a porous structure include a plating method such as electrolytic plating and electroless plating, and a squeegee printing method using a paste of metal particles. Among these, electroless plating is advantageous because it has an advantage that an electrode having a uniform height can be formed in the surface. Since the electrode having a porous structure is relatively fragile, the second electrode can be easily pierced.
There is no restriction | limiting in particular in the shape in planar view of the recessed part 51. FIG. The depth of the recess 51 is not particularly limited, but can be, for example, about 2 to 5 micrometers (μm).

  On the bonding surface 10B of the second semiconductor substrate 101, a second electrode 61 that is electrically connected to the wiring of the second semiconductor substrate 101 or the like is formed. The second electrode 61 has a shape in which at least the tip end portion has a cross-sectional area smaller than the cross-sectional area of the first electrode 52 when viewed in the thickness direction of the second semiconductor substrate 101 and can enter the recess 51. ing. FIG. 3 shows, as an example, a substantially rod-shaped or column-shaped second electrode, but instead of this, a cone-shaped or frustum-shaped shape in which a body in a certain region on the tip side can enter the recess 51. Etc.

  An underfill layer 31 is formed between the bonding surfaces 10 </ b> A and 10 </ b> B to seal the space around the second electrode 61. The material of the underfill layer 31 may be appropriately selected from various known materials in consideration of the electrode formation pitch and the like.

Since the protrusion length h1 of the second electrode 61 from the bonding surface 10B is set to be sufficiently larger than the thickness t1 of the underfill layer 31, the second electrode 61 breaks through the underfill layer 31 in the semiconductor device 120. The first electrode 52 is entered so as to enter the recess 51 and pierce the first electrode 52.
From the viewpoint of reliably breaking through the underfill layer 31, the protrusion length h1 is preferably 1.5 times or more the thickness t1. Alternatively, the protrusion length h1 is set to be not less than the sum of t1 and 1/3 × d1 so that the protrusion amount h2 of the second electrode 61 from the underfill layer 31 is 25% or more of the depth d1 of the recess 51. Is also preferred. If the protruding length h1 is larger than the sum of t1 and d1, even if the second electrode 61 reaches the bottom surface of the concave portion 51, the underfill layer 31 and the bonding surface 10B are not sufficiently in contact with each other, and there is a gap between them. It is preferable to avoid it.
The second electrode 61 is preferably formed of a material having sufficient rigidity with respect to the underfill layer 31 and the first electrode 52. For example, tungsten (W) or nickel (Ni) is exemplified as a suitable material. Can do.

An example of a method for manufacturing the semiconductor device 120 configured as described above will be described.
First, the first semiconductor substrate 1 and the second semiconductor substrate 101 are formed. An example of the procedure for forming the first semiconductor substrate 1 and the second semiconductor substrate 101 is shown below.
An insulating layer having a predetermined thickness is formed of an oxide film or the like on the surface of the base material 10 on which the wiring or the like is formed, and a recess 51 is formed by photolithography, etching, or the like, and the wiring or the like is exposed on the bottom of the recess 51. After that, when the first electrode 52 is formed by arranging a conductive material appropriately selected in the recess 51 by a method such as plating, PVD, CVD, or printing, the first semiconductor substrate 1 is completed (first substrate forming step). ).
If the 2nd electrode 61 is formed on the surface of the other base material 10 in which wiring etc. were formed and exposed, the 2nd semiconductor substrate 101 will be completed (2nd board | substrate formation process). The second electrode 61 can be formed using substantially the same method as the first electrode 52.

  Next, an appropriately selected resin material is applied onto the bonding surface 10A of the first semiconductor substrate 1 to form an underfill layer 31 having a desired thickness (underfill layer forming step). At this time, since the first electrode 52 is formed in the recess 51 and does not protrude on the bonding surface 10A, it is not necessary to consider the entire periphery of the electrode and the underfill layer 31 is simply formed in layers. Just do it. There is no restriction | limiting in particular in the formation method of the underfill layer 31, It can select suitably from materials, etc. in consideration of well-known various methods, such as a spin coat method, a squeegee printing method, and a vacuum laminating method.

Next, as shown in FIG. 4, the first semiconductor substrate 1 and the second semiconductor substrate 101 are brought into contact with each other with the bonding surface 10A and the bonding surface 10B facing each other, and pressurization is performed using a press device or the like. Pressure bonding process). At this time, the underfill layer 31 is not completely cured. Further, the first semiconductor substrate 1 is heated as necessary, and the rigidity of the first electrode 52 is adjusted so that the second electrode 61 can be easily stuck into the first electrode 52.
Due to the pressurization, the second electrode 61 first penetrates the underfill layer 31 and then enters the recess 51 to pierce the first electrode 52.
As described above, the first semiconductor substrate 1 and the second semiconductor substrate 101 are bonded together in a state where the bonding surface 10A and the bonding surface 10B are sealed by the underfill layer 31, and the first electrode 52 and the second semiconductor substrate 101 are bonded. The electrode 61 is electrically connected. Thereafter, when the above-described individualization is performed, the semiconductor device 120 is completed. It should be noted that the singulation may be performed as necessary and is not essential in the method for manufacturing a semiconductor device of the present invention.

  As described above, according to the semiconductor device 120 and the manufacturing method thereof of the present embodiment, the second electrode 61 formed on the second semiconductor substrate 101 breaks through the underfill layer 31 and the first semiconductor substrate 1. The first electrode 52 is formed so as to sufficiently enter the first electrode 52. As a result, the first electrode and the second electrode can be reliably connected while reliably sealing the periphery of the second electrode with the underfill layer 31 even if the resin material is pre-applied. Generation | occurrence | production can be suppressed suitably.

  Further, since the second electrode 61 has sufficiently entered the first electrode 52, the second electrode 61 is in contact with the first electrode 51 not only at the tip surface but also at the side surface. Therefore, in the pressure bonding process, when the second electrode 61 penetrates the underfill layer 31, even if a part of the underfill remains on the tip surface, it contacts with the first electrode at another part. Thus, the electrical connection between the electrodes can be reliably ensured. Furthermore, since the underfill adhering to the surface of the second electrode 61 is suitably removed by contacting the first electrode 52 when the second electrode 61 enters the inside of the first electrode 52, the electrical connection Reliability is improved.

  Furthermore, since the first electrode 52 into which the second electrode 61 pierces is formed in the recess 51, the alignment (alignment) accuracy between the first semiconductor substrate 1 and the second semiconductor substrate 101 in the pressure bonding step. Even if this is not sufficient, the peripheral wall of the recess 51 functions as a guide, so that the second electrode 61 can be guided to pierce the first electrode 52 to some extent, and the reliability of electrode joining can be improved. . Furthermore, since the first electrode 52 disposed in the recess 51 is not greatly deformed in the surface direction of the bonding surface 10A by pressurization, occurrence of bonding failure due to deformation in the surface direction can be suitably suppressed. .

  Furthermore, in the underfill layer forming step, since the electrode does not protrude on the bonding surface 10A, it is possible to easily form an underfill layer that uniformly seals the periphery of the electrode simply by applying a resin material in layers. .

  As mentioned above, although one embodiment of the present invention has been described, the technical scope of the present invention is not limited to the above-described embodiment, and combinations of components or components may be changed without departing from the spirit of the present invention. It is possible to make various changes to or delete them.

  For example, in the above-described embodiment, the case where two semiconductor substrates are bonded has been described as an example. However, a semiconductor device may be formed by bonding a larger number of semiconductor substrates. In that case, for example, electrodes may be formed on both surfaces of a semiconductor substrate located in the middle, and these electrodes may be appropriately connected by wiring or the like. At this time, there is no restriction | limiting in particular in the electrode formed, A 1st electrode or a 2nd electrode may be formed in both surfaces, a 1st electrode is formed in one surface, and a 2nd electrode is formed in the other surface. It may be formed. Which electrode is formed may be determined according to the mode of the electrode formed on the mating semiconductor substrate to be joined.

  Furthermore, the type of the semiconductor device of the present invention is not particularly limited. For example, in a solid-state imaging device having a large number of pixels, for example, a very large number such as a circuit electrode diameter or a circuit electrode formation pitch is 20 micrometers. Therefore, the advantage obtained by applying the present invention is very great, and it is very suitable for applying the structure of the present invention.

1 Semiconductor substrate (first semiconductor substrate)
31 Underfill layer 51 Recess 52 First electrode 61 Second electrode 101 Second semiconductor substrate 120 Semiconductor device

Claims (6)

A semiconductor device comprising a first semiconductor substrate and a second semiconductor substrate bonded to the first semiconductor substrate,
Comprising an underfill layer formed between the first semiconductor substrate and the second semiconductor substrate;
The first semiconductor substrate has a recess provided on one surface, and a first electrode disposed in the recess,
The second semiconductor substrate has a second electrode shaped so that at least a part thereof can enter the recess,
The semiconductor device, wherein the first electrode and the second electrode are connected by the second electrode penetrating the first electrode through the underfill layer.   2. The semiconductor device according to claim 1, wherein the protruding length of the second electrode is 1.5 times or more the thickness of the underfill layer.   The protruding length of the second electrode is not less than the sum of the thickness of the underfill layer and the value of 1/3 of the depth of the recess, and not more than the sum of the thickness of the underfill layer and the depth of the recess. The semiconductor device according to claim 1.   The semiconductor device according to claim 1, wherein the first electrode is formed using a metal so as to have a porous structure.   A solid-state imaging device comprising the semiconductor device according to claim 1. A first substrate forming step of forming a first semiconductor substrate having a recess provided on one surface and a first electrode disposed in the recess;
A second substrate forming step of forming a second semiconductor substrate having a second electrode shaped so that at least a part thereof can enter the recess;
An underfill layer forming step of forming an underfill layer by applying an underfill on the one surface of the first semiconductor substrate;
The first semiconductor substrate and the second semiconductor substrate are brought into contact with the second electrode facing the one surface, and the second electrode penetrates the underfill layer and penetrates the first electrode. A pressure bonding step of applying pressure to bond the first semiconductor substrate and the second semiconductor substrate;
A method for manufacturing a semiconductor device, comprising:

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