JPH0577339B2 - - Google Patents

Abstract

PURPOSE:To prevent a crack from being caused while a thermal stress is absorbed by using a coupling particle and to enhance heat-dissipating performance by forming a gap between substrates by a method wherein, when the semiconductor substrates for lamination use are laminated three-dimensionally, the semiconductor substrates are laminated mutually by using the coupling particle. CONSTITUTION:A conductive coupling particle composed of a metallic substance which has been filled into a hard cylindrical body and a hard cylindrical body, whose inside diameters differ from each other, in such a way that the particle protrudes partly from an end part at the side of a smaller inside diameter is fixed to a pad 3 of a coupling hole 7 in a semiconductor substrate 6 for lamination use. As this fixing method, the semiconductor substrate 6 for lamination use is set on a retention stage 35 in such a way that an opening of the coupling hole 7 faces upward; after that, a gun barrel 32 is aligned with the coupling hole 7 in the semiconductor substrate 6. A temperature of the retention stage 35 is increased to 300 deg.C by using a built-in heater 34; after that, the outside of the gun barrel 32 is maintained at about 350 deg.C by using a heater 31; a conductive coupling particle 19 is inserted into the gun barrel 32 and is discharged with accelerated velocity while the coupling particle 19 is being heated by compressed nitrogen 36. The semiconductor substrate 6 for lamination use where the conductive coupling particle 19 has been fixed to an exposed part of the pad 3 corresponding to the coupling hole 7 via a protruding part 17 is thereby obtained.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a semiconductor device, and relates to a semiconductor device having a three-dimensional structure in which a plurality of semiconductor substrates on which semiconductor elements and the like are formed are laminated. .

(Prior Art) In recent years, three-dimensional SOI (Silicon on Insulation) devices have been actively developed for the purpose of increasing the integration and multifunctionality of semiconductor devices. This is a technique in which a silicon single crystal is formed on an amorphous insulating film on the surface of a semiconductor substrate, a semiconductor element is manufactured using the single crystal layer, and the semiconductor elements are stacked three-dimensionally. This technology is described, for example, in Nikkei Electronics October 17, 1985 issue, p. 229-253, “Three-dimensional LSI emerging as a highly integrated, multifunctional device.”
It is described in.

However, SOI technology is still in the early stages of development and has a number of drawbacks in terms of practical application.
The essential disadvantages are that different materials are laminated in multiple layers and single crystallization is progressed through a high-temperature process, so the stress is extremely large and cracks are likely to occur, and the layers have a close contact structure. Therefore, heat dissipation is low and heat is easily trapped.Furthermore, it is impossible with current technology to stack semiconductor materials other than silicon.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned problems of crack generation and deterioration of heat dissipation caused by three-dimensionalization, and achieves high reliability and
The present invention aims to provide a semiconductor device that achieves high integration and multifunctionality.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a method in which a semiconductor element is formed at least,
and a semiconductor substrate having a plurality of pads formed on a predetermined portion of the surface, and a connecting hole opened in the thickness direction at a location corresponding to the pad formed on the surface so as to expose at least a part of the back surface of the pad. and at least one laminated semiconductor substrate on which a semiconductor element is formed, and the hard cylindrical body has an inner diameter near one end smaller than an inner diameter near the other end. The cylindrical body is filled with connecting grains so as to protrude from one end of the cylindrical body, and the cylindrical body is fixed to the back surface of the pad exposed from the connecting hole of the laminated semiconductor substrate via the protrusion of the connecting grains, The semiconductor substrate for lamination and the semiconductor substrate are:
It is characterized in that the connecting grains exposed at the other end of the cylindrical body are laminated by fixing them to other conductive connecting grains arranged on the pad side of the semiconductor substrate.

(Function) The present invention provides a structure in which between a semiconductor substrate on which a semiconductor element, etc. is formed, and a laminated semiconductor substrate on which the same element is formed,
Further, by fixing and connecting the semiconductor substrates for stacking to the exposed portion of the pad corresponding to the connecting hole of the semiconductor substrate for stacking and the pad on the other side via conductive connecting grains, the semiconductor substrates for stacking are bonded and connected to each other via conductive connecting grains. Substrates can be stacked three-dimensionally.

Further, since the semiconductor substrates are laminated with each other using connected grains, thermal stress can be absorbed by the connected grains, and the occurrence of cracks as in the conventional SOI structure can be prevented.

Further, since the semiconductor substrates are laminated with each other by connecting grains, and a desired distance can be formed between the substrates, heat is not trapped between the substrates, and heat dissipation is improved. In particular, since it is possible to circulate the coolant between the substrates, a significant heat dissipation effect can be exhibited.

Furthermore, the conductive connecting grains fixed to the pads in the connecting holes of the semiconductor substrate for lamination are filled with hard cylindrical bodies having different inner diameters, and into the cylindrical bodies so as to partially protrude from the end on the smaller inner diameter side. Since the pad is made of a metal body, it can be easily fixed to the pad via the protrusion of the metal body. Moreover, even if a mechanical force is applied to the entire connected grain when fixing the connected grain to the pad, the hard cylindrical body can prevent deformation in the direction perpendicular to the axis, so the deformation of the connected grain can be prevented. Accordingly, it is possible to prevent short-circuiting due to contact with the semiconductor substrate exposed on the inner surface of the connecting hole.

(Examples of the Invention) Examples of the invention will be described in detail below along with manufacturing methods.

() First, the thickness is
On a 450 μm silicon wafer 1, semiconductor elements, interconnections between the elements (none of which are shown), and 50 μm×50 μm pads 2 and 3 made of an Al film were formed.
Of these pads, a part of the pad 3 corresponding to the connecting hole to be filled later is embedded in the opening formed in the interlayer insulating film, and a thin oxide layer is formed on the substrate surface at the bottom of the opening. A film is formed.
This oxide film is used to prevent electrical connection of the pad to the substrate surface, which would be an obstacle in the die sort test. However, instead of the thin oxide film, a thin oxide film is formed on the surrounding substrate surface including the bottom of the opening.
An impurity diffusion layer may be formed to create a pn junction. Subsequently, the back surface of the silicon wafer 1 corresponding to the pad 3 is etched by a combination of isotropic etching and anisotropic etching to form an opening of 30 μm×.
A round hole 4 having a diameter of 30 μm and a depth of 50 μm was drilled (as shown in FIG. 1a). In addition, etching is
Both experiments were carried out using fluorine-based gas plasma.

() Next, after performing a die sort test on the silicon wafer, dicing is performed to produce individual chips, which are then sorted to produce 5 good chips.
was obtained (as shown in FIG. 1b). Subsequently, the entire back surface of the non-defective chip 5 was subjected to anisotropic etching to produce a thin plate-shaped semiconductor substrate 6 for lamination having a thickness of 45 μm (as shown in FIG. 1c). In this anisotropic etching process, the wine cup-shaped hole 4 opened on the back surface is etched while substantially maintaining its shape, so that a tapered connecting hole 7 is formed. Also, during the etching, the thin oxide film at the bottom of the opening was removed,
A pad 3 is provided at the bottom of the connecting hole 7 corresponding to the opening.
exposed part of.

() Next, the pad 3 of the connecting hole 7 of the semiconductor substrate 6 for lamination is filled with a hard cylindrical body having different inner diameters and a metal body filled in the cylindrical body so as to partially protrude from the end on the smaller inner diameter side. The manufacturing method of the conductive connected grains will be explained with reference to FIGS. As shown in FIGS. 3a and 3b, it consists of a connected grain fixing machine 33 consisting of a gun barrel 32 with an inner diameter of 40 μm and a heater 31 disposed on the outside, and a holding table 35 with a built-in heater 34 on which a semiconductor substrate is set. This will be explained with reference to the device.

First, a photoresist film 12 with a thickness of about 20 μm is applied on the support base 11, and then a ceramic cylinder 13 mainly made of alumina and having an outer diameter of 60 μm, an inner diameter of 20 μm, and a length of 50 μm is placed on the support base 11. The cylindrical body 13 was fixed upright so that the lower end was covered with the resist film 12 (see Fig. 2a).
(Illustrated). Subsequently, the cylindrical body 13 was etched by approximately 3 μm by immersing it in a mixed acid solution containing hydrofluoric acid and nitric acid as main components. After etching, the resist film is removed to create different diameters as shown in FIG.
A ceramic cylindrical body 14 with a diameter of 20 μm was fabricated. Subsequently, as shown in FIG. 2c, by using compressed air, the gold foil 16 with a thickness of 50 μm placed on the support stand 15 is driven with the large inner diameter side of the cylindrical body 14 as the tip. Gold (Au) protruded approximately 10 μm from the rear end of the small inner diameter side. After this, the cylindrical body 14 filled with gold is placed on the supporting base 15.
As shown in FIG. 2d, a hard cylindrical body 14 having different inner diameters and a metal having a protrusion 17 protruding from the end on the small inner diameter side filled in the cylindrical body 14 are obtained. Body (Au body) 1
Conductive connected grains 19 consisting of 8 were manufactured.

Next, as shown in FIG. 3a, the semiconductor substrate 6 for lamination is set on the holding table 35 so that the opening of the connecting hole 7 is facing upward, and then the gun barrel 32 is set.
was aligned with the connecting hole 7 of the semiconductor substrate 6. Next, the temperature of the holding base 35 is raised to 300°C by the built-in heater 34, and then the outside of the gun barrel 32 is maintained at about 350°C by the heater 31.
The conductive connecting grains 19 manufactured by the method described above are inserted into the gun barrel 32, and the compressed nitrogen 36 heats the connecting grains 19 while emitting radiation with acceleration, as shown in FIG. 3b. Then, the Au protrusion 17 protruding from the small inner diameter side of the cylindrical body 14 of the connecting grain 19 was fixed by hot pressure welding onto the exposed portion of the pad 3 at the bottom of the connecting hole 7. Note that 8 in FIG. 3b is an interlayer insulating film for electrically insulating the substrate 6 and the pad 3, and 9 is the insulating film 8.
This is an opening for exposing a part of the pad 3 to the bottom of the connecting hole 7. Through these steps, a ceramic cylindrical body 14 with an irregular side surface is formed in the exposed part of the pad 3 corresponding to the connecting hole 7 shown in FIG.
The conductive connected grains 19 consisting of the body 18 are connected to the protrusion 17
A semiconductor substrate 6 for lamination was obtained which was fixed through the wafer.

() Next, the thickness was determined using a two-dimensional LSI manufacturing method.
A 50 μm x 50 μm pad consisting of a semiconductor element, wiring between elements, and an Al film was formed on a 450 μm silicon wafer. Subsequently, after the die sort test, the silicon wafer is diced, non-defective chips 21 are selected, and the above-mentioned connected grain fixing machine is used to place the chips on the pads 22 on the surface of the non-defective chips 21.
Au particles 23 having a spherical shape with a diameter of 40 μm were fixed (as shown in FIG. 1e).

() Next, the semiconductor substrate 6 for lamination produced in the steps () to () above is placed on the good chip 21 produced in the step () above, and the Au grains 23 on the pads 22 of the chip 21 and the semiconductor substrate 6 are placed on top of the non-defective chip 21 produced in the step () above. After stacking the conductive connecting grains 19 in the connecting hole 7 so that the ends of the large inner diameter side coincide with each other, the semiconductor substrate 6 for lamination is pressed against the chip 21 while heating to 300°C, thereby removing the Au grains. 23 and connected grain 19
The Au bodies 18 were fixed to each other (as shown in FIG. 1f). Subsequently, spherical Au particles 24 were bonded and fixed by thermocompression onto predetermined pads 2 and 3 on the surface of the stacked semiconductor substrates 6 using the above-mentioned connecting fixing machine (as shown in FIG. 1g).

() Next, a plurality of thin plate-shaped semiconductor substrates for lamination are produced by the same steps as in () to () above,
These semiconductor substrates were sequentially stacked on top of the semiconductor substrate 6 stacked as shown in FIG.

Therefore, in the semiconductor device of the present invention, the semiconductor substrate 6 for lamination is connected between the non-defective chip 21 on which a semiconductor element or the like is formed and the semiconductor substrate 6 for lamination on which the same element is formed, and further between the semiconductor substrates 6 for lamination 6. A hard cylindrical body 14 and the cylindrical body 1 having different inner diameters in the exposed part of the pad 3 corresponding to the hole 7 and the mating pad 22.
The conductive connecting grains 19 made of the Au body 18 having the protruding part 17 that is filled in the inner diameter part 4 and protruding from the end on the small inner diameter side are fixed and laminated via the Au grains 23 and 24. A semiconductor device having a three-dimensional functional structure can be obtained.

Furthermore, since the non-defective chip 21, the semiconductor substrate for lamination 6, and the lamination between the semiconductor substrates for lamination 6 and each of the semiconductor substrates for lamination 6 are made of the conductive connecting grains 19 and the Au grains 23, 24, the Au body of the connecting grains 19 is 18,
Because it can be absorbed by Au grains 23 and 24, it
It is possible to prevent cracks from occurring in structures. Moreover, for the same reason, a desired distance between the non-defective chip 21 and the semiconductor substrate 6 for lamination, and between each semiconductor substrate 6 is maintained.
Since gaps can be formed between the substrates, heat is not trapped between the substrates, and heat dissipation is improved. Therefore, a semiconductor device having a highly reliable three-dimensional structure can be obtained.

Further, the conductive connecting grains 19 fixed to the pads 7 in the connecting holes 7 of the semiconductor substrate 6 for lamination are connected to a hard cylinder 14 having different inner diameters, and the ends of the cylinders 14 are filled in the small inner diameter side. A protrusion 17 protruding from the
Since it is composed of an Au body 18 having
The Au body 18 can be easily and reliably fixed to the pad 3 via the protrusion 17. Moreover, even if mechanical force is applied to the entirety of the conductive connecting grains 19 when fixing them to the pads 3 in the connecting holes 7, the hard cylindrical body 14 prevents deformation in the direction perpendicular to the axis thereof. It can be prevented. As a result, it is possible to prevent short circuits caused by contact between the Au bodies 18 constituting the connection grains 19 and the stacking semiconductor substrate 6 exposed on the inner surface of the connection hole 7. In particular, as in the example, the cylindrical body 1 is made of ceramic.
4, the connection hole 7 of the semiconductor substrate 6 for lamination is formed.
When the conductive connecting grains 19 are fixed to the inner pad 3,
The connecting grains 19 can prevent the connecting grains 19 from coming into contact with the laminating semiconductor substrate 6 exposed on the inner surface of the connecting hole 7 and causing a short circuit between the connecting grains 19 and the laminating semiconductor substrate 6 due to the cylindrical body 14. The alignment accuracy during fixing can be made rough, and the productivity of semiconductor devices can be improved. For the same reason, the short circuit can be prevented without tapering the connecting hole, so that miniaturization of the connecting hole and simplification of manufacturing of the semiconductor device can be achieved.

In the above embodiment, the hard cylindrical body constituting the conductive connected grains is made of ceramic containing alumina as a main component, but the present invention is not limited thereto. For example, the cylindrical body may be formed of ceramics other than alumina such as mullite and silicon nitride, glass, heat-resistant organic synthetic resins such as polyimide, hard metals such as stainless steel, or a material made by bonding metal and ceramic.

In the above embodiment, gold (Au) was used as the metal body, but for example, Al foil may be used instead of gold foil in the step shown in FIG. 2c described above. Furthermore, Ag−Pt, Au
- A conductive paste consisting of conductor powder of Pd, Mo, and W and a binder is applied onto a supporting substrate, and the cylindrical bodies of different diameters prepared in Figure b are implanted into the conductive paste layer and fired. You may manufacture the electroconductive connected grain shown in d.

In the above example, an example was explained in which conductive connecting grains whose side surfaces were covered with an insulating material were fixed to pads in the connecting holes. 24) may be used as electrically conductive connected grains made of hard cylinders having different inner diameters and metal bodies filled in the cylinders so as to partially protrude from the end on the smaller inner diameter side.

In the above embodiment, a structure in which only a plurality of laminated semiconductor substrates made of silicon are used and these laminated semiconductor substrates are laminated on a chip has been described, but the present invention is not limited to this. For example, a wiring board is inserted between the semiconductor substrates for lamination via a connecting grain, and a current path is established between the semiconductor substrate for lamination on the lower side and the semiconductor substrate for lamination on the upper side with the wiring substrate as a boundary. It may be changed. Further, as shown in FIG. 4, a chip 51 is formed of silicon, a silicon semiconductor substrate 52 and a gallium arsenide semiconductor substrate 53 are laminated on this silicon chip 51, and further these silicon semiconductor substrate 52 and gallium arsenide semiconductor substrate 53 are laminated. The semiconductor device may have a three-dimensional structure in which a silicon semiconductor substrate 54 is stacked on top. With the configuration shown in FIG. 4, it is possible to easily realize a semiconductor device with a three-dimensional structure that has more functions than the conventional SOI structure.

[Effects of the Invention] As detailed above, the present invention prevents the occurrence of cracks due to thermal stress, has excellent heat dissipation, and has a highly integrated and highly integrated structure that can be multi-functional compared to conventional SOI structures. A semiconductor device with a reliable three-dimensional structure can be provided.

[Brief explanation of the drawing]

Figures 1a to 1g are cross-sectional views showing the manufacturing process for obtaining a three-dimensionally structured semiconductor device of the present invention, and Figure 2a
- d are cross-sectional views showing the manufacturing process of the conductive connected grains used in this example, and Figures 3 a and b show the connected grains manufactured according to Figures 2 a to d in the pads of the connecting holes of the semiconductor substrate for lamination. FIG. 4 is a cross-sectional view showing the fixing process, and FIG. 4 is a cross-sectional view showing a three-dimensional semiconductor device according to another embodiment of the present invention. 1... Silicon wafer, 2, 3, 22... Pad, 6... Semiconductor substrate for lamination, 7... Connecting hole, 8
... Interlayer insulating film, 9 ... Opening part, 12 ... Support stand, 13, 32 ... Gun barrel, 14 ... Ceramic cylindrical body, 17 ... Protrusion part, 18 ... Gold body (Au
body), 19... Conductive connected grains, 21... Good chips, 23, 24... Au grains, 33 ... Connected grain fixing machine, 35... Holding stand, 51... Silicon chips,
52, 54...Silicon semiconductor substrate, 53...Gallium arsenide semiconductor substrate.

Claims (1)

[Scope of Claims] 1. A semiconductor substrate on which at least a semiconductor element is formed and a plurality of pads are formed on a predetermined portion of the surface, and a connecting hole is formed on the back surface of the pad at a location corresponding to the pad formed on the surface. at least one laminated semiconductor substrate having an opening in the thickness direction so as to expose at least a portion thereof and on which a semiconductor element is formed; The cylindrical body is filled with conductive connecting particles made of a metal body so as to protrude from one end of the cylindrical body, and the cylindrical body is arranged so that the back surface of the pad exposed from the connecting hole of the semiconductor substrate for lamination is are fixed to each other through the protruding portions of the connected grains, and the semiconductor substrate for lamination and the semiconductor substrate are
A semiconductor device characterized in that the semiconductor device is stacked by fixing the connecting grain exposed at the other end of the cylindrical body to another conductive connecting grain arranged on the pad side of the semiconductor substrate. 2. The conductive connecting grains used in addition to the conductive connecting grains fixed to the pads in the connecting holes of the semiconductor substrate for lamination are hard cylindrical bodies having a shape in which an inner diameter near one end is smaller than an inner diameter near the other end. 2. The semiconductor device according to claim 1, further comprising a metal body filled inside the cylindrical body so as to protrude from one end of the cylindrical body. 3. A plurality of the semiconductor substrates for lamination are prepared, and each of the semiconductor substrates for lamination has pads in areas other than the areas corresponding to the connecting holes, and the pads other than the connecting holes of the semiconductor substrate for lamination in the first layer are different from each other. The exposed part of the back surface of the pad corresponding to the connecting hole of the second layer semiconductor substrate for lamination is placed inside a hard cylindrical body having a shape in which the inner diameter near one end is smaller than the inner diameter near the other end. Conductive connecting grains made of a metal body filled in such a way as to protrude from one end are used to adhere to each other and stack, and in the same way, semiconductor substrates for lamination from the third layer onwards are sequentially connected to the conductive connecting grains and the cylinder. 2. The semiconductor device according to claim 1, wherein the semiconductor device is stacked by being fixed to each other using conductive connecting particles filled inside the semiconductor device. 4. The thickness of the semiconductor substrate for lamination is determined by a conductive metal body filled in a hard cylindrical body having an inner diameter near one end smaller than an inner diameter near the other end so as to protrude from one end. 2. The semiconductor device according to claim 1, wherein the height is substantially the same as that of the connected grains.