JP2001230432A - Semiconductor device and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device whose yield is improved, manufacture is easy and reliability is high, to provide the semiconductor device whose reliability is high without the need of a special manufacturing device, and to provide the semiconductor device which prevents the increase of parasitic capacitance by the leading of wiring an whose performance and reliability are high. SOLUTION: A hemispherical semiconductor substrate and an element area formed on the flat face of the semiconductor substrate are installed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor device and a method of manufacturing the same, and more particularly, to a structure of a semiconductor device using a hemispherical semiconductor.

[0002]

2. Description of the Related Art Conventionally, a semiconductor integrated circuit is formed by slicing a semiconductor single crystal ingot pulled up by a Czochralski (Cz) method or the like, forming a semiconductor wafer, and performing a surface treatment such as mirror polishing. After forming an element region and forming a wiring layer, dicing is performed to form a semiconductor chip, and the semiconductor chip is packaged.

[0003] In order to improve the yield, the diameter of the semiconductor ingot has been increasing, and preparation for practical use of a semiconductor ingot having a large diameter of 300 mm has been advanced. However, pulling large-diameter single crystals without defects requires special equipment such as a large-scale furnace, and requires control of temperature and pulling speed. ing.

Further, there are many defects, many parts cannot be used as devices, and material waste is large. Under these circumstances, there has been a limit to the cost reduction of semiconductor chips using a conventional wafer as a starting material.

In recent years, there has been proposed a technique of manufacturing a semiconductor device by forming a circuit pattern on a spherical semiconductor (Ball Semiconductor) having a diameter of 1 mm or less such as single crystal silicon. However, forming a circuit on a spherical surface requires control of an ultimately complicated optical system, and at present, no process technology has been established.

As one of them, a method of manufacturing a solar array in which a large number of semiconductor particles are connected by using an aluminum foil has been proposed (Japanese Patent Laid-Open No. Hei 6-13633). In this method, as shown in FIG. 13, semiconductor particles 207 having a first conductivity type skin portion and a second conductivity type interior are arranged in an opening of an aluminum foil so as to protrude from both sides of aluminum foil 201, and a skin on one side is provided. The portion 209 is removed, and an insulating layer 221 is formed. Next
Part of 2-conductivity-type interior 211 and insulating layer 221 thereon
Is removed, and the second aluminum foil 2
Combine 19 The flat region 217 provides a good ohmic contact with the second aluminum foil 219 as a conductive portion.

[0007]

However, in such a method, there is a limit in high-density arrangement, and it is difficult to position on an aluminum foil, and particularly when a large number of semiconductor particles are mounted. There was a problem that workability was poor. In addition, such a solar cell requires an inverter circuit for converting DC to AC. However, since this inverter circuit is connected to the solar cell via the aluminum foil 219, the wiring distance is long, and another semiconductor circuit is required. Since it must be prepared as a chip, there has been a problem that it is difficult to miniaturize the device.

Further, when connecting to a logic circuit chip, the wiring length from the terminal for extracting the electromotive force from the solar cell to the logic circuit chip driven by the electromotive force is increased, and the occurrence of parasitic capacitance and the like are increased. This has led to various problems.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a highly reliable semiconductor device which is easy to manufacture and improves the yield. An object of the present invention is to provide a highly reliable semiconductor device without requiring a special manufacturing device. It is another object of the present invention to provide a high-performance and highly reliable semiconductor device by preventing an increase in parasitic capacitance due to wiring routing.

[0010]

In order to achieve the above object, a first semiconductor device of the present invention comprises forming an element region in a flat surface of a semi-spherical semiconductor substrate having a spherical surface and a flat surface. Characterized in that: According to such a configuration, a semiconductor sphere such as a spherical single-crystal silicon is cut near the equator and an element region is formed on this flat surface. This is unnecessary, and the pattern can be formed using a conventional optical system device. Further, since it is a hemisphere, the mechanical strength is extremely large as compared with the semiconductor chip, there is no possibility of breakage, and the yield is greatly improved.

According to a second aspect of the present invention, in the first semiconductor device, a bump for external connection is further provided along a periphery of the flat surface. According to such a configuration, the hemisphere can be surface-mounted on the mounting substrate in an extremely stable shape, and the mounting area is small and stable mounting is possible.

According to a third aspect of the present invention, in the first semiconductor device, a rearranged wiring is formed on the flat surface via an insulating film, and a bump for external connection is provided on the entire surface. It is characterized by. According to such a configuration, in addition to the above-described effects, the entire flat surface can be used as an external connection portion, and reliable and stable connection can be performed without increasing the mounting area. Furthermore, the wiring length can be made uniform, and an increase in parasitic capacitance caused by the wiring length can be reduced.

In a fourth aspect of the present invention, in the first semiconductor device, a semiconductor element is further formed on a spherical surface of the semiconductor substrate. According to such a configuration, for example, a solar cell or a light-emitting element or the like is formed on the spherical surface, and the connection to the outside and the processing circuit can be formed on a flat surface, that is, a flat surface. A stable and highly reliable semiconductor device can be formed.

According to a fifth aspect of the present invention, in the semiconductor device according to the fourth aspect, the semiconductor element on the spherical surface and a part of the element region formed on the flat surface are electrically connected. It is characterized by. According to this configuration, since the circuit between the spherical surface and the plane portion is connected inside the hemisphere, it is possible to reduce the wiring length and to provide a highly reliable semiconductor device with a small occupied area. It becomes possible.

According to a sixth aspect of the present invention, in the semiconductor device according to the fifth aspect, a solar cell is formed on the spherical surface, and an inverter circuit is formed on the flat surface. According to this configuration, it is possible to reduce the occupied area and obtain a semiconductor device having a large light receiving area.

According to a seventh aspect of the present invention, in the semiconductor device according to the sixth aspect, a pn junction is formed between the first conductivity type semiconductor layer formed on the surface of the sphere and the first semiconductor layer. The formed second conductive type semiconductor layer, an outer electrode made of a transparent conductive film formed on the surface of the second semiconductor layer, and connected to the first conductive type semiconductor layer and extracted to the surface A spherical solar cell portion comprising an inner electrode, and a semiconductor integrated circuit portion formed by forming an inverter circuit formed on the flat surface, an outer electrode and an inner electrode of the spherical solar cell portion, The spherical semiconductor integrated circuit is interconnected inside the hemisphere. According to such a configuration, in addition to the above effects, it is possible to provide a solar cell that is easy to manufacture and has high reliability.

Further, a light emitting diode may be formed on the surface of the sphere, and a control circuit for controlling light emission of the light emitting diode may be provided on the flat surface. According to such a configuration, the occupied area is small and light emission from the entire surface is possible, so that it is possible to obtain a light emitting device with high luminance even when viewed from an oblique direction. Furthermore, the light emitting diode may be formed over the entire surface of the sphere.

An eighth aspect of the present invention is a step of forming a semiconductor sphere, a step of dividing the semiconductor sphere into two near the equator to form a hemispherical semiconductor,
A step of forming a desired element region; and a step of forming a wiring layer on the flat surface. According to this configuration, two hemispheres can be obtained from one semiconductor sphere, and waste of material can be eliminated.

According to a ninth aspect of the present invention, in the method of manufacturing a semiconductor device according to the eighth aspect, the cutting step includes:
A step of laying the tray in a row, filling the tray with a resin, curing together with the laid semiconductor balls, and integrally fixing a large number of semiconductor spheres, and performing positioning with the resin fixed. Cutting along with the resin so as to form a flat surface passing through the center of each semiconductor sphere. According to such a configuration, when performing the division into two, high-precision positioning can be reliably performed, and the flat surface can be divided so as to form a flat surface as an aggregate, and post-processing is also easy. Becomes

A tenth aspect of the present invention is the method of manufacturing a semiconductor device according to the ninth aspect, further comprising a step of integrally mirror-polishing the flat surface with the resin remaining. According to such a configuration, it is possible to obtain further flatness of the flat surface.

According to an eleventh aspect of the present invention, in the method of manufacturing a semiconductor device according to the tenth aspect, the step of forming the element region and the step of forming a wiring layer are integrally performed while the resin remains. It is characterized by doing so.
According to this configuration, it is possible to perform batch processing while maintaining high positional accuracy for a large number of semiconductor devices,
A highly reliable semiconductor device can be formed with extremely high workability.

According to a twelfth aspect of the present invention, in the method of manufacturing a semiconductor device according to the eleventh aspect, there is further provided a step of integrally forming a bump in a predetermined region on the wiring layer while leaving the resin. It is characterized by including. According to such a configuration, since the bumps can be formed with good flatness, it is possible to provide a semiconductor device with extremely high mounting reliability.

Preferably, in the method of manufacturing a semiconductor device according to claim 12, a step of attaching a tape to the flat surface, and removing the resin while fixing the tape.
A step of forming a desired element region on the spherical surface of the hemisphere. According to this configuration, since the element can be formed on the sphere surface by being integrally fixed with the tape, batch processing can be performed while maintaining high positional accuracy, and a highly reliable semiconductor can be obtained. The device can be formed with extremely high workability.

According to a thirteenth aspect of the present invention, in the method of manufacturing a semiconductor device according to the eighth aspect, the step of forming the semiconductor sphere comprises: forming a semiconductor substrate at least on a spherical substrate surface constituting a semiconductor layer of the first conductivity type; Preparing a plurality of cells in which a second conductivity type semiconductor layer formed to form a junction and an outer electrode formed of a transparent conductive film formed on the surface of the second semiconductor layer are formed. The step of fixing the semiconductor spheres is a step of fixing using a transparent resin, and the step of forming a desired element region on the flat surface and the step of forming the wiring layer while fixing with the transparent resin. It is characterized in that it is executed. According to such a configuration,
Since the surface can be fixed with a transparent resin and the element region can be collectively formed on a flat surface, a highly reliable semiconductor device with extremely high workability can be formed.

[0025]

Next, embodiments of the present invention will be described in detail with reference to the drawings. Embodiment 1 A solar cell according to a first embodiment of the present invention is shown in FIG.
As shown in a plan view in FIG. 2, an element region is formed on a plane portion 11F of the hemispherical single-crystal silicon 11 surrounded by a hemispherical surface and a flat surface to constitute an IC circuit portion 11R.
It is characterized in that bumps 2 for bonding are formed. The sphere surface is covered with a metal film 11M.

FIG. 3 is a diagram showing a cross section of a main part of FIG. The IC circuit portion 11R is formed by forming a source / drain region 112 and a gate electrode 113 on a substrate surface surrounded by an element isolation insulating film 111, and further forming a wiring 114 so as to contact the source / drain region. It is.
Then, as shown in FIG. 4, the semiconductor device is mounted via a bump 2 on a printed board 120 on which a wiring pattern (not shown) is formed. And this bump 2
Is sealed with a polyimide resin 121. Here, for example, the IC circuit unit 11R uses a logic IC, a memory IC, and an RF coil juxtaposed.

Next, a method of manufacturing the semiconductor device will be described. First, a single crystal silicon sphere 11 is formed. Then, as shown in FIG. 5A, the surface of the n-type single crystal silicon sphere 11 having a diameter of 1 mm is mirror-polished and washed,
A tungsten film 11M is formed as a metal film by a CVD method. Here, in the CVD process, while the silicon sphere is transported in a thin tube, W heated to a desired reaction temperature is used.
By supplying and discharging reactive gas such as F6 gas,
This is for forming a thin film. Here, this metal film is for surface protection and heat dissipation.

The single-crystal silicon spheres 11 thus formed are spread in a row on a tray T as shown in FIG. 5B, and then the wax 10 is poured into the tray T and cured. Then, as shown in FIG. 5C, the bottom surface is positioned, and the spherical cell is cut with a diamond saw from the center so as to be divided in the middle. After this, FIG.
As shown in (1), the cut surface is mirror-polished, an element isolation insulating film 111 is formed by a LOCOS method, and an element region is formed. Then, as shown in FIG. 5E, a gate insulating film and a gate electrode 113 are sequentially formed, and are patterned. Using the gate electrode as a mask, impurity diffusion is performed to form a source / drain region 112 and the like. Then, the wiring layer 114 is formed.

Finally, the solder bumps 2 are formed, and the wax 10 is removed to separate the solder bumps 2 one by one.
Thus, the semiconductor device as shown in FIGS. 1 and 2 is completed.

At the time of mounting, it is positioned on a printed circuit board on which a wiring pattern is formed, and heated to
It can be easily mounted. According to such a configuration, since only the element is formed on a plane, a conventional process can be used. It can be easily formed with good workability.

Since the hemispherical surface is covered with the metal film 11M, it is stable and has good heat radiation. Furthermore, a plurality of silicon spheres can be handled and processed integrally, and since this process only requires a planar process, the workability is extremely good and the reliability is high. In addition, when the metal film 11M is spherical, the outside of the metal film 11M may be covered with a resin film in advance. After the division, the entire hemispheric surface may be covered with a resin film.

In the above embodiment, the bumps 2 are formed along the periphery of a square. However, as shown in a modification of FIG. 6, the bumps 2 may be formed along the periphery of a circle constituting a flat surface. Good. According to such a configuration, wiring becomes easier and the wiring length can be reduced. In addition, depending on the device, the wiring length can be made uniform, and the variation in wiring capacitance can be reduced.

As shown in FIG. 7, a bump 2 may be formed on the entire flat surface by adopting a rearranged wiring structure.

Embodiment 2 Next, a second embodiment of the present invention will be described. As shown in FIG. 8, this semiconductor device is characterized in that a solar cell section 30 is formed on a spherical surface of hemispherical single-crystal silicon and an inverter circuit section 20 is formed on a flat surface that is a cut surface. It is assumed that.

That is, the solar cell section has a 1 mm diameter p.
An outer electrode made of a transparent conductive film made of indium tin oxide (ITO) so that an n-type polycrystalline silicon layer 12 is formed on the spherical surface of the semi-spherical single-crystal silicon to form a pn junction and further cover this surface. 13 are formed. And so as to contact this outer electrode,
An electrode portion is formed on the periphery of the flat surface, and connection to the outside is made by two bumps 2S formed opposite to each other. On the other hand, a transistor circuit is formed on a flat surface so as to be connected to p-type hemispherical single-crystal silicon. That is, the p-side of this solar cell is connected to one of the source and drain of the transistor of the inverter circuit formed internally on a flat surface. This inverter circuit is formed on a flat surface, and is configured so that the surface can be mounted on a mounting board such as a printed board by the bump 2I. FIG. 9 is a diagram showing a modification of the semiconductor device. The bumps 2I of the inverter circuit section 20 may be formed only on the periphery.

Next, a method of manufacturing the semiconductor device will be described. First, as shown in FIG. 10A, the surface of a p-type single-crystal silicon sphere 11 having a diameter of 1 mm is mirror-polished, washed, and n-type is formed by a CVD method using a mixed gas such as silane containing phosphine. A polycrystalline silicon layer 12 is formed. Here, the CVD process can be easily and efficiently performed by transporting the single-crystal silicon spheres in a gas atmosphere heated to a desired reaction temperature, and by switching the atmosphere while sequentially transporting in a pipe. A plurality of thin films can be formed.

Thereafter, as shown in FIG. 10 (b), an I-type film having a thickness of about 1 μm is formed on the entire surface of the substrate by sputtering.
A TO thin film 13 is formed.

Then, FIG. 1 thus formed is formed.
As shown in FIG. 11B, the solar cells 1 shown in FIG. 1A are spread in a line on a tray T, and a wax 15 made of a transparent resin is poured into the tray T and cured.

Then, as shown in FIG. 11C, the bottom surface is positioned, and the spherical cell is cut with a diamond saw from the center so as to be divided in the middle. Thereafter, as shown in FIG. 11D, the cells are horizontally arranged such that the cells are positioned above while being fixed with wax, and an element isolation insulating film 111 is formed by a LOCOS method.

Then, a gate oxide film is formed by a CVD method, a gate electrode 113 is formed, and source / drain diffusion is performed to form a source / drain region 112. Thereafter, as shown in FIG. 11E, a wiring layer 114 is formed by using normal photolithography.

After the element region is formed in this way, a bump is finally formed to complete the solar cell as shown in FIG. According to such a configuration, the sphere on which the pn junction and the outer electrode are formed is arranged in a close-packed state in a state where the sphere is spread on the tray, and is fixed with a transparent resin, thereby fixing the sphere with a high degree of positional accuracy. By cutting the hemisphere, it is possible to obtain a hemisphere with extremely high precision.

After the cutting, a plurality of hemispherical silicons are fixed integrally without removing the resin.
A pattern exposure is performed on a flat surface using a normal photolithography process to form an inverter circuit composed of a transistor circuit. Therefore, a highly reliable semiconductor device can be extremely easily formed without a complicated optical system. Can be provided.

If the bumps are formed and are directly mounted on a mounting substrate such as a printed circuit board, a highly reliable solar cell with extremely high positional accuracy can be provided. In the above embodiment, since the resin used for fixing is left as it is, it is possible to provide a highly reliable semiconductor device which is positioned with high accuracy. Furthermore, this resin can also exert the effect of improving moisture resistance.

The resin may be removed prior to mounting. High-efficiency solar cells made of hemispheres arranged closest can be formed with high productivity.

Furthermore, since the two separated assemblies are used as one solar cell, respectively, there is no waste of material and the productivity is extremely high. Also,
According to this method, a mask step is not required for a spherical surface. In particular, the photolithography process for a spherical body is extremely difficult to expose, but according to the method of the present invention, a highly efficient solar cell can be formed without the need for a photolithography process for a spherical surface. It is possible to do.

FIG. 13 shows the printed circuit board 12 of this solar cell.
This is an example of mounting to 0. Here, 121 is a resin.

In the above embodiment, single-crystal silicon is used as a semiconductor layer for forming a pn junction. However, the present invention is not limited to this. For example, a polycrystalline silicon layer or an amorphous silicon layer, and GaAs, GaP, etc. It is also applicable to the compound semiconductor layer of the above. Further, the present invention can be applied to not only a pn structure but also a pin structure.

In the production of this spherical semiconductor device, each processing step can be connected to form a line.
It is characterized by extremely high productivity.

In each step, the treatment is performed in various atmospheres including not only gases such as active gas and inert gas, but also liquids such as water and various solutions. In the case of connecting such processing steps, it is necessary to prevent the atmosphere for transporting the workpiece from being carried from the previous step to the subsequent step. It is necessary to convert the atmosphere to the process and transport the workpiece.However, using a pressure difference or using an atmosphere converter that uses a tornado, each process can be performed while transporting. This makes it possible to provide a highly reliable semiconductor device which is extremely fast, has good workability, and is highly reliable.

When it is necessary to make the wiring capacitance uniform, by forming the wiring of the same length toward the center, it is possible to reduce the variation of the wiring capacitance caused by the variation of the wiring length. Becomes possible.

[0051]

As described above, according to the present invention, a semiconductor integrated circuit is formed on a flat surface of a hemispherical semiconductor. For example, since an inverter circuit is provided on a flat surface, a small and highly efficient semiconductor device can be provided.

In addition, a solar cell portion is formed on the surface portion of one spherical semiconductor which is easy to receive light, and a solar cell portion is formed on the back surface having a small amount of received light, thereby obtaining a solar cell with higher efficiency. Becomes possible.

[Brief description of the drawings]

FIG. 1 is a diagram showing a solar cell according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a cell constituting the solar cell according to the first embodiment of the present invention.

FIG. 3 is a sectional view of a main part of a cell constituting the solar cell according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a manufacturing apparatus for manufacturing the solar cell according to the first embodiment of the present invention.

FIG. 5 is a sectional view of a cell constituting the solar cell according to the first embodiment of the present invention.

FIG. 6 is a diagram showing a modification of the present invention.

FIG. 7 is a diagram showing a modification of the present invention.

FIG. 8 is a diagram showing a solar cell according to a second embodiment of the present invention.

FIG. 9 is a view showing a modification of the solar cell according to the second embodiment of the present invention.

FIG. 10 is a diagram showing a manufacturing process of the solar cell according to the second embodiment of the present invention.

FIG. 11 is a diagram showing a manufacturing process of the solar cell according to the second embodiment of the present invention.

FIG. 12 is a diagram showing a mounting example of a solar cell according to a second embodiment of the present invention.

FIG. 13 shows a conventional solar cell.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Single crystal silicon sphere 11M Metal film 2 Bump 2S bump 2I Bump 11R Inverter circuit part 11F Flat part 111 Element isolation insulating film 112 Source drain region 113 Gate electrode 114 Wiring 120 Mounting substrate 11 p-type single crystal silicon sphere 12 n-type polycrystal Silicon layer 13 Outer electrode

Claims (13)

[Claims] 1. A semiconductor device comprising a hemispherical semiconductor substrate having a spherical surface and a flat surface, wherein an element region is formed in the flat surface. 2. The semiconductor device according to claim 1, further comprising a bump for external connection along a peripheral edge of said flat surface. 3. The semiconductor device according to claim 1, wherein rearranged wiring is formed on the flat surface via an insulating film, and bumps for external connection are provided on the entire surface. 4. The semiconductor device according to claim 1, further comprising a semiconductor element formed on a spherical surface of said semiconductor substrate. 5. The semiconductor device according to claim 4, wherein the semiconductor element on the spherical surface and a part of the element region formed on the flat surface are electrically connected. 6. The semiconductor device according to claim 5, wherein a solar cell is formed on the spherical surface, and an inverter circuit is formed on the flat surface. 7. A semiconductor layer of the first conductivity type formed on the surface of the sphere, the first semiconductor layer, a semiconductor layer of the second conductivity type formed to form a pn junction, and the semiconductor layer of the second conductivity type. An outer electrode made of a transparent conductive film formed on the surface of the second semiconductor layer, and a spherical solar cell portion comprising an inner electrode connected to the first conductive type semiconductor layer and taken out on the surface, A semiconductor integrated circuit portion formed by forming an inverter circuit formed on the flat surface, wherein an outer electrode and an inner electrode of the spherical solar cell portion and the spherical semiconductor integrated circuit are interconnected inside the hemisphere. 7. The semiconductor device according to claim 6, wherein: 8. A step of forming a semiconductor sphere; a step of dividing the semiconductor sphere into two near the equator to form a hemispherical semiconductor; and forming a desired element region on a flat surface of the hemispherical semiconductor. And a step of forming a wiring layer on the flat surface. 9. The cutting step includes: laying semiconductor spheres in a line in a tray; filling the tray with a resin, curing the semiconductor spheres together with the laid semiconductor spheres, and integrally fixing a large number of semiconductor spheres. 9. The semiconductor device according to claim 8, further comprising: a step of performing positioning in a state of being fixed with the resin, and cutting together with the resin so as to form a flat surface passing through the center of each semiconductor sphere. Manufacturing method. 10. The method of manufacturing a semiconductor device according to claim 9, further comprising the step of integrally mirror-polishing the flat surface with the resin remaining. 11. The semiconductor device according to claim 10, wherein the step of forming the element region and the step of forming the wiring layer are integrally performed with the resin remaining. Production method. 12. The method of manufacturing a semiconductor device according to claim 11, further comprising the step of integrally forming a bump in a predetermined region on said wiring layer while leaving said resin. . 13. The step of forming a semiconductor sphere comprises: forming a pn junction on a surface of a spherical substrate having at least a surface constituting a semiconductor layer of the first conductivity type.
Preparing a plurality of cells in which a conductive type semiconductor layer and an outer electrode made of a transparent conductive film formed on the surface of the second semiconductor layer are provided; and the step of fixing the semiconductor sphere is transparent. A step of forming a desired element region on the flat surface and a step of forming the wiring layer while fixing with the transparent resin. Item 9. The method for manufacturing a semiconductor device according to item 8.