Patent Application
20110115055
The disclosure of Japanese Patent Application No. 2009-262797 filed on Nov. 18, 2009 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
The present invention relates to semiconductor devices, a module and manufacturing methods thereof, and more particularly, to a technique effectively applied to a semiconductor device with a Zener diode and a manufacturing method thereof.
Japanese Unexamined Patent Publication No. Hei 06 (1994)-252384 (Patent Document 1) discloses a structure which includes a first conductive thin film for electrically coupling an anode pseudopotential intake region of a thyristor to a cathode region of a protective diode, and a second conductive thin film separately provided from the first thin film to cover the cathode region of the protective diode and a periphery of the cathode region.
Light emitting diodes (hereinafter referred to as a LED) have been widely used for various types of luminaires, such as a fluorescent light or a back light of a liquid crystal display, because of lower power consumption and longer life time. The LED is a semiconductor element whose market is expected to grow in the future.
A method for obtaining white light from the LED involves irradiating a garnet phosphor (YAG phosphor) with blue light emitted from a blue LED to thereby obtain the white light. Some blue LEDs have a low surge resistance, and hence are required to ensure the adequate surge resistance in order to be used for applications with high reliability.
Measures for ensuring the surge resistance involves, by way of example, coupling a Zener diode in anti-parallel to the LED. When coupling the Zener diode in anti-parallel to the LED, for example, a surge voltage applied to the LED by static electricity from the outside is also applied to the Zener diode coupled in anti-parallel to the LED. The Zener diode exhibits a breakdown and permits current in the reverse direction when the applied surge voltage exceeds the breakdown voltage. At this time, the voltage applied to the Zener diode exhibiting the breakdown keeps a Zener voltage. The Zener voltage is smaller than the surge voltage. That is, when the surge voltage is applied to the LED, the Zener diode coupled in anti-parallel to the LED is also subjected to the surge voltage, so that the breakdown of the Zener diode occurs. The voltage applied to the broken-down Zener diode becomes the constant Zener voltage. That is, upon the breakdown of the Zener diode, the surge voltage is absorbed by the Zener diode, and then converted into the Zener voltage. Thus, the LED coupled in anti-parallel to the Zener diode is subjected to the Zener voltage lower than the surge voltage. That is, the use of the Zener diode which is designed to make the Zener voltage lower than the breakdown voltage of the LED can protect the LED from the surge voltage. For the above reason, the Zener diode is used to protect the LED from the surge voltage.
The Zener diode with such a function is packaged separately from the LED, and is used as an external device for the LED. The LEDs, however, are required to be downsized. For this reason, mounting of the external Zener diode and the LED in the same package has been under consideration. Mounting a semiconductor chip with the LED and another semiconductor chip with the Zener diode in the same package poses the following new problems. Specifically, resin used in the package of the LED is transparent, and the LED itself emits light, so that the semiconductor chip with the Zener diode formed is consequently irradiated with the light. Thus, the p-n junction in the Zener diode is also irradiated with the light. In this case, electrons and holes generated by a photoelectric effect are moved by an electric field existing in the p-n junction, resulting in an increase in leak current. The increase in leak current from the Zener diode leads to a decrease in current which is to flow through the LED, which causes an increase in loss of the current. That is, when the leak current at the Zener diode is increased, more current is required to cause the LED to emit light, which wastes much current not contributing to the emission of light from the LED. This disadvantageously raises the problem of the increase in current loss.
Accordingly, it is an object of the present invention to provide a technique that can decrease the leak current due to the photoelectric effect in a semiconductor device with a Zener diode.
The above and other objects and the novel features of the invention will become apparent from the description of the present specification and the accompanying drawings.
The outline of representative aspects of the invention disclosed in the present application will be briefly described below.
A semiconductor device according to a representative embodiment of the invention includes a bidirectional Zener diode formed in a first semiconductor chip. At this time, the bidirectional Zener diode includes (a) a semiconductor substrate of a first conductive type, (b) a first semiconductor region of a second conductive type opposite to the first conductive type which is formed over the semiconductor substrate, and (c) a second semiconductor region of the first conductive type which is formed over the first semiconductor region. The Zener diode also includes (d) an isolation region formed in a predetermined depth from a surface of the second semiconductor region, and (e) a protective insulating film which is formed over the surface of the second semiconductor region so as to cover the second semiconductor region and the isolation region, and which has an opening formed for exposing a part of the second semiconductor region. The Zener diode further includes (f) a light blocking film formed over the protective insulating film including the opening, and (g) a back electrode formed at a back side of the semiconductor substrate. The light blocking film extends from an inside of the opening to cover the isolation region.
A manufacturing method of a semiconductor device according to another representative embodiment of the invention includes the steps of (a) preparing a semiconductor substrate of a first conductive type, and (b) forming a first semiconductor region of a second conductive type opposite to the first conductive type over the semiconductor substrate. The manufacturing method also includes the steps of (c) then forming a second semiconductor region of the first conductive type in an area from an inside to a surface of the first semiconductor region, and (d) forming an isolation region reaching in a predetermined depth from the surface of the second semiconductor region to isolate an active region. The manufacturing method further includes the steps of (e) subsequently forming a protective insulating film over the second semiconductor region and the isolation region, and (f) forming an opening in the protective insulating film formed in the active region by processing the protective insulating film to expose the second semiconductor region from the opening. The manufacturing method additionally includes the steps of (g) forming a light blocking film over an area from the second semiconductor region exposed from the opening to the protective insulating film, and (h) processing the light blocking film. At this time, in the step (h), the light blocking film is processed so as to extend from an inside of the opening to cover the isolation region.
The effects obtained by the representative aspects of the invention disclosed in the present application will be briefly described below.
Therefore, a semiconductor device with a Zener diode is provided which can reduce the leak current due to the photoelectric effect.
The following preferred embodiments of the invention may be described below by being divided into a plurality of sections or embodiments for convenience, if necessary, which are not independent from each other except when specified otherwise. One of the sections or embodiments is a modified example, the details, a supplemental explanation, or the like of a part or all of the other.
When reference is made to the number of elements or the like (including the number of pieces, numerical values, quantity, range, etc.) in the following description of the embodiments, the number thereof is not limited to a specific number, and may be greater than, or less than, or equal to the specific number, unless otherwise specified and definitely limited to the specific number in principle.
It is also needless to say that components (including elements or process steps, etc.) employed in the following description of the embodiments are not always essential, unless otherwise specified and considered to be definitely essential in principle.
Similarly, in the following description of the shapes, positional relations and the like of the components or the like in the embodiments, they will include those substantially analogous or similar to their shapes or the like, unless otherwise specified and considered not to be definitely so in principle, etc. This is also similarly applied even to the above-described numerical values and range.
Members having the same functions are designated by the same reference numerals through all drawings for explaining the embodiments of the invention in principle, and thus the repeated description thereof will be omitted. For easy understanding, hatched areas are given even to plan views.
A light-emitting diode is a semiconductor device that emits light by causing a direct current to flow therethrough. The principle of light emission of the light-emitting diode is as follows. Specifically, when a p-n junction provided in the light-emitting diode is forward biased, holes are implanted from a p-type semiconductor region and electrons are implanted from an n-type semiconductor region into the p-n junction. The electrons recombine with the holes at the p-n junction. In the recombination, the electrons in a conduction band of a band structure meet the holes in a valance band, while releasing energy corresponding to the band gap. That is, in the recombination, the energy corresponding to the band gap is released. The release of the energy corresponding to the band gap is performed by emitting light with the energy corresponding to the band gap. The semiconductor device using this phenomenon is a light-emitting diode. The light-emitting diode can change the band gap by selecting material. The light-emitting diode emits light equivalent to the energy corresponding to the band gap. Thus, the change of the band gap leads to a change in energy of the emitted light. The energy of light is proportional to the frequency of light (E=hν). The change in energy of the emitted light means the change in frequency of the emitted light. That is, in the light-emitting diode, light with different frequencies can be emitted by changing the band gap. In other words, the production of light-emitting diodes with different band gaps can provide the light-emitting diodes emitting lights in different colors. Specifically, the light-emitting diodes emitting red, green, and blue lights are produced.
Such light-emitting diodes have been widely used for various types of luminaires, such as a fluorescent light or a back light of a liquid crystal display, because of lower power consumption and longer life time. Some LEDs have a low surge resistance, and hence are required to ensure the adequate surge resistance in order to be used for applications with high reliability.
Measures for ensuring the surge resistance involves, by way of example, coupling a Zener diode in anti-parallel to the light-emitting diode.
The above single light-emitting diode LED is sometimes used, but a plurality of light-emitting diodes LEDs are combined together in use so as to further increase the light intensity.
For this reason, the bidirectional Zener diode IZD and not the normal Zener diode ZD is used as a device coupled in anti-parallel to the light emitting diode LED.
Further, the use of the bidirectional Zener diode IZD has the advantage that the light-emitting diode LED can be protected from serge voltages with different polarities. In either case where the surge voltage with a different polarity is applied to the bidirectional Zener diode IZD, the surge voltage is applied in the reverse direction with respect to the corresponding bidirectional Zener diode IZD. In each case, the breakdown of the bidirectional Zener diode IZD occurs, so that the surge voltage is absorbed and converted into the Zener voltage. Thus, even when the surge voltages with different polarities are applied to the light-emitting diodes LED, the light-emitting diode LED can be protected from the surge voltage.
In particular, only one bidirectional Zener diode LZD can protect the light-emitting diode LED from the surge voltage with different polarities. In contrast, in the case of using the normal Zener diode, two Zener diodes coupled in the reverse direction are required to protect the light-emitting diodes LEDs from the serge voltages with different polarities. This means an increase in mounting area of the Zener diodes. In order to protect the light-emitting diodes LEDs from the surge voltages with different polarities, two normal Zener diodes are needed as the device. However, the use of the only one bidirectional Zener diode IZD as the device can also achieve the effect. As a result, the use of the bidirectional Zener diode IZD can reduce the mounting area about by half as compared to the use of the two Zener diodes.
The first embodiment of the invention is a technical idea based on the premise of using the bidirectional Zener diode IZD with the above advantages. There are various device structures that achieve the bidirectional Zener diode IZD. The first embodiment relates to the so-called trench bidirectional Zener diode IZD. Now, the first embodiment will describe the reason for selecting the trench bidirectional Zener diode IZD in use from among the device structures achieving the bidirectional Zener diode IZD. A module structure (a package structure, a semiconductor device) related to
In the bidirectional Zener diode IZD shown in
For example, suppose that the surge voltage is applied to the bidirectional Zener diode IZD shown in
The p-n junction is formed at a boundary between the n-type semiconductor region NR1 and the p-type semiconductor region PR in the bidirectional Zener diode IZD shown in
The bidirectional Zener diode IZD shown in
In the bidirectional Zener diode IZD shown in
As can be seen from the above description, the bidirectional Zener diode IZD shown in
Next, the device structure of the trench bidirectional Zener diode IZD will be described below.
A pair of trenches TR is formed to reach the inside of the semiconductor substrate 1a from the surface of the p-type semiconductor region PR through the p-type semiconductor region PR and the n-type semiconductor region NR. A region interposed between the pair of trenches TRs is an active region serving as the bidirectional Zener diode IZD. In other words, in the trench bidirectional Zener diode IZD, the active region is isolated by the pair of trenches TRs, and the isolated active region has the bidirectional Zener diode IZD formed therein.
A protective insulating film IF1 is formed over the surface of the p-type semiconductor region PR with the trenches TRs formed therein. Specifically, the protective insulating film IF1 is formed over the surface of the p-type semiconductor region PR including the inner surfaces of the trenches TRs. The protective insulating film IF1 is comprised of, for example, a silicon oxide film, a silicon nitride film, a phospho silicate glass (PSG) film which is a glassy film provided by adding phosphorus into a silicon oxide film, or the like.
An opening OP is formed in the protective insulating film IF1, and an upper electrode UE is formed over the protective insulating film IF1 including the opening OP. Specifically, the opening OP is formed in the active region interposed between a pair of trenches TRs, and the p-type semiconductor region PR is exposed at the bottom of the opening OP. The upper electrode UE is formed over the protective insulating film IF1 in the active region from the inside of the opening OP. In this way, the upper electrode UE is in contact with the p-type semiconductor region PR exposed at the bottom of the opening OP. The upper electrode UE is comprised of a conductive film, such as a metal film or a metal compound film, for example, an aluminum-silicon film.
The trench bidirectional Zener diode IZD with this arrangement has the following advantages. In the trench bidirectional Zener diode IZD, the n-type semiconductor region NR is formed over the entire upper surface of the semiconductor substrate 1S, and the p-type semiconductor region PR is formed over the entire upper surface of the n-type semiconductor region NR. In the trench bidirectional Zener diode IZD, both the boundary between the semiconductor substrate 1S and the n-type semiconductor region NR, and the boundary between the n-type semiconductor region NR and the p-type semiconductor region PR are flat horizontal ones. This means that a region with a small curvature radius is not formed in the boundary between the semiconductor substrate 1S and the n-type semiconductor region NR, and in the boundary between the n-type semiconductor region NR and the p-type semiconductor region PR. That is, in the trench bidirectional Zener diode IZD, the steep junction end with the small curvature radius is not formed, unlike the bidirectional Zener diode IZD shown in
The respective p-n junctions are formed at the horizontal boundary between the semiconductor substrate 1S and the n-type semiconductor region NR, and at the horizontal boundary between the n-type semiconductor region NR and the p-type semiconductor region PR in the trench bidirectional Zener diode IZD. Thus, when the reverse bias voltage is applied to each of the p-n junctions, the depletion layer extends only in the vertical direction from each p-n junction. That is, the depletion layer does not extend from the p-n junction of the junction end in the lateral direction (horizontal direction) in the trench bidirectional Zener diode IZD shown in
The trench bidirectional Zener diode IZD with such a function is normally packaged separately from the light-emitting diode LED and used as an exterior device for the light-emitting diode LED. The LEDs, however, are required to be downsized. For this reason, the external bidirectional Zener diode IZD and the light-emitting diode LED are considered to be mounted in the same package. Mounting the semiconductor chip with the light-emitting diode LED and another semiconductor chip with the bidirectional Zener diode IZD in the same package raises the following new problems. In other words, when mounting the semiconductor chip with the trench bidirectional Zener diode IZD and the semiconductor chip with the light-emitting diode LED in the same package, the following problems are raised. The problems will be described below.
The resin used in the package of the light-emitting LED is transparent, and the light-emitting diode LED itself emits light, so that the semiconductor chip with the trench bidirectional Zener diode IZD is consequently irradiated with the light. At this time, as shown in
Thus, the first embodiment is based on the premise of using the trench bidirectional Zener diode IZD which is mounted together with the light-emitting diode LED in one package. The trench bidirectional Zener diode IZD of the first embodiment has means for decreasing leak current due to the photoelectric effect. The following will describe the trench bidirectional Zener diode IZD that can reduce the leak current due to the photoelectric effect with reference to the accompanying drawings.
A pair of trenches TR is formed to reach the inside of the semiconductor substrate 1S from the surface of the p-type semiconductor region PR through the p-type semiconductor region PR and the n-type semiconductor region NR. An area interposed between the pair of trenches TRs is an active region serving as the bidirectional Zener diode IZD. In other words, in the trench bidirectional Zener diode IZD, the active region is isolated by the pair of trenches TRs. The bidirectional Zener diode IZD is formed in the isolated active region.
In the bidirectional Zener diode IZD of the first embodiment, the trench TR has the following functions. For example, suppose that no trench TR is formed. Also in this case, the n-type semiconductor region NR is formed over the upper surface of the p-type semiconductor substrate 1S, and the p-type semiconductor region PR is formed over the n-type semiconductor region NR. The PNP junction is formed, and serves as the bidirectional Zener diode IZD. When the trench TR is not formed, however, the PNP junction reaches the end of the semiconductor substrate 1S. That is, in a case where no trench TR is formed, the active region serving as the bidirectional Zener diode IZD reaches the end of the semiconductor substrate 1S. In other words, the PNP junction for determining the electric characteristics of the bidirectional Zener diode IZD is formed up to the end of the semiconductor substrate 1S.
The end of the semiconductor substrate 1S is cut by dicing. Thus, if the PNP junction that determines the important properties of the bidirectional Zener diode IZD is formed up to the end of the semiconductor substrate 1S, the PNP junction may be damaged by the dicing. This may result in variations in characteristics of the bidirectional Zener diode IZD.
Contaminants tend to enter the end of the semiconductor substrate 1S from the outside. When the PNP junction that determines the important properties of the bidirectional Zener diode IZD is formed up to the end of the semiconductor substrate 1S, the PNP junction may be affected by the contaminants, which results in variations in characteristics of the bidirectional Zener diode IZD.
In contrast, when the trenches TRs are formed, the region interposed between the pair of trenches TRs becomes the active region for the bidirectional Zener diode IZD. That is, the trench TR can separate the active region of the bidirectional Zener diode IZD from the outside end region thereof. As a result, even when the end of the semiconductor substrate 1S is cut by dicing, the PNP junction of the bidirectional Zener diode IZD positioned inside the trench TR is protected without being damaged. Since contaminants invading the end of the semiconductor substrate 1S are interrupted by the trenches TRs, the PNP junction of the bidirectional Zener diode IZD which is formed inside the trench TR is protected from the pollutant. Accordingly, the formation of the trench TR can suppress variations in characteristics of the bidirectional Zener diode IZD. In other words, the trench TR serves as an isolation region for separating the active region of the bidirectional Zener diode IZD from the end region of the semiconductor substrate 1S.
The protective insulating film IF1 is formed over the surface of the p-type semiconductor region PR with such trenches TRs formed therein. Specifically, the protective insulating film IF1 is formed over the surface of the p-type semiconductor region PR including the inner walls of the trenches TRs. The protective insulating film IF1 is comprised of, for example, a silicon oxide film, a silicon nitride film, a phospho silicate glass (PSG) film which is a glassy film provided by adding phosphorus into a silicon oxide film, or the like.
The opening OP is formed in the protective insulating film IF1, and the upper electrode UE is formed over the protective insulating film IF1 including the opening OP. Specifically, the opening OP is formed in the active region interposed between a pair of trenches TRs, and the p-type semiconductor region PR is exposed at the bottom of the opening OP. In the first embodiment, the upper electrode UE is formed to extend from the inside of the opening OP over the protective insulating film IF1 covering the inner wall of the trench TR. Thus, the upper electrode UE is in contact with a part of the p-type semiconductor region PR exposed at the bottom of the opening OP. The upper electrode UE is comprised of a conductive film, such as a metal film or a metal compound film, for example, an aluminum-silicon film.
The first feature of the first embodiment is that the upper electrode UE extends from the inside of the opening OP to cover the trench TR (isolation region). That is, as shown in
The formation of the upper electrode UE so as to cover the inner wall of the trench TR can also obtain the following advantages. For example, when the trenches TR are formed in the upper surface (front surface) side of the semiconductor substrate 1S, warpage tends to occur in the semiconductor substrate 1S due to a difference in stress between the surface of the semiconductor substrate 1S with the trench TR formed therein and the back surface of the substrate 1S without the trench TR. At this time, since the upper electrode UE is formed so as to cover the inner walls of the trenches TRs in the first embodiment, the upper electrode UE formed over the inner walls of the trenches TRs releases the warpage of the semiconductor substrate 1S. In other words, in the first embodiment, the upper electrode UE is formed to cover the inner walls of the trenches TRs for the purpose of preventing the light from entering the p-n junction formed at the boundary between the n-type semiconductor region NR and the p-type semiconductor region PR from the inner wall of the trench TR. This arrangement can also have a spillover effect for preventing the warpage of the semiconductor substrate 1S.
Next, the second feature of the first embodiment is that the upper electrode UE formed so as to cover the inner wall of the trench TR is not formed up to the end region of the semiconductor substrate 1S. For example, if the upper electrode UE is formed up to the end region of the semiconductor substrate 1S, the upper electrode UE may corrode in contact with moisture entering the end region of the semiconductor substrate 1S from the outside, which may result in variations in characteristics of the bidirectional Zener diode IZD. In contrast, the upper electrode UE in the bidirectional Zener diode IZD of the first embodiment does not extend up to the end region of the semiconductor substrate 1S, so that the moisture entering the end region of the substrate 1S from the outside can be prevented from being brought into contact with the upper electrode UE. Thus, the first embodiment can suppress the corrosion of the upper electrode UE, and thus can improve the reliability of the bidirectional Zener diode IZD.
The upper electrode UE not formed up to the end region of the semiconductor substrate 1S can obtain the following advantages. For example, when the upper electrode UE is formed up to the end region of the substrate 1S which is an outside region of the trench TR, the presence of defects of the formed protective insulating film IF1 brings the upper electrode UE into direct contact with the semiconductor region formed under the protective insulating film IF1. Then, the semiconductor region inside the trench TR (active region) may be coupled to the semiconductor region outside the trench TR, which may cause variations in characteristics of the diode. That is, the bidirectional Zener diode IZD does not possibly work. In contrast, in a case where the upper electrode UE does not extend to an outer end region of the trench TR like the first embodiment, the upper electrode UE can be prevented from being in direct contact with the semiconductor region in the end region even if the protective insulating film IF1 formed in the outer end region has defects. Thus, in the first embodiment, even when the protective insulating film IF1 has some defects in the outer end region of the trench TR, the contact between the upper electrode UE and the semiconductor region can be prevented, which can suppress variations in characteristics of the bidirectional Zener diode IZD to thereby improve the reliability of the bidirectional Zener diode IZD.
Further, the bidirectional Zener diode IZD of the first embodiment has the following advantage.
Now, a modified example of the bidirectional Zener diode IZD in the first embodiment will be described below.
The bidirectional Zener diode IZD of the first embodiment is structured as mentioned above, and a manufacturing method thereof will be described below with reference to the accompanying drawings. First, as shown in
Subsequently, as shown in
Then, as shown in
Therefore, as shown in
Then, as shown in
Subsequently, as shown in
As shown in
Then, as shown in
As mentioned above, the bidirectional Zener diode IZD of the first embodiment can be manufactured. In the bidirectional Zener diode IZD of the first embodiment, the inner surface of each trench TR is covered with the upper electrode UE (light blocking film) having the light blocking effect. Thus, even when light is applied to the bidirectional Zener diode IZD, the light can be prevented from entering the p-n junction formed at the boundary between the n-type semiconductor region NR and the p-type semiconductor region PR from the inner wall of the trench TR. According to the first embodiment, the leak current due to the photoelectric effect can be reduced.
A second embodiment of the invention will describe an example in which the inside of the trench TR is filled with a filling membrane.
Since the inside of the trench TR is filled with the polysilicon film PF1, the surface of the trench TR is aligned with the surface of the p-type semiconductor region PR. As a result, the flatness is improved over the surface of the trench TR filled with the polysilicon film PF1 and the surface of the p-type semiconductor region PR, which advantageously facilitates formation of the protective insulating film IF1 over the p-type semiconductor region PR including the trench TR.
Although the second embodiment has described the example in which the inside of the trench TR is filled with the polysilicon film PF1 via the insulating film IF2, only the insulating film may be embedded in the trench TR.
Also, in the bidirectional Zener diode IZD of the second embodiment, an upper electrode UE extends from the inside of an opening OP to cover the trench TR (isolation region), like the bidirectional Zener diode IZD of the first embodiment. Thus, even when light is applied to the bidirectional Zener diode IZD, the light can be prevented from entering the p-n junction formed at the boundary between the n-type semiconductor region NR and the p-type semiconductor region PR from the inner wall of the trench TR. Thus, the occurrence of the photoelectric effect in the p-n junction can be suppressed. That is, the bidirection Zener diode IZD of the second embodiment can reduce the leak current flowing from the n-type semiconductor region NR to the p-type semiconductor region PR due to the photoelectric effect in the p-n junction. This means that, for example, the current passing through the light-emitting diode LED coupled in parallel to the bidirectional Zener diode IZD can be ensured to reduce the loss of the current. Since the leak current at the bidirectional Zener diode IZD can be reduced, the Zener diode IZD can improve the efficiency of use of current for emission of light from the light-emitting diode LED to thereby reduce the useless current not contributing to the light emission of the light-emitting diode LED. In this way, the bidirectional Zener diode IZD of the second embodiment can reduce the leak current due to the photoelectric effect, and as a result, can improve the efficiency of use of current at the diode LED.
The bidirectional Zener diode IZD of the second embodiment has the structure described above, and a manufacturing method thereof is substantially the same as that of the first embodiment. Specifically, the steps shown in
A third embodiment of the invention will describe an example in which an isolation region is formed of the semiconductor region.
As mentioned above, in the third embodiment, the isolation region is formed not from the trench TR like the first and second embodiments, but from the n-type semiconductor region NR2. This has an advantage that the step of forming the trench TR can be omitted. Since no trench TR is formed, the surface of the p-type semiconductor region PR is aligned with the surface of the n-type semiconductor region NR2 serving as the isolation region, which advantageously facilitates formation of the protective insulating film IF1 over the p-type semiconductor region PR including the n-type semiconductor region NR2 (isolation region).
Also in the bidirectinal Zener diode IZD of the third embodiment, like the bidirectinal Zener diode IZD of the first embodiment, the upper electrode UE extends from the inside of the opening OP to cover the isolation region (n-type semiconductor region NR2). Even when the light is applied to the bidirectional Zener diode IZD, the light can be prevented from entering the p-n junction formed at the boundary between the n-type semiconductor region NR and the p-type semiconductor region PR. Thus, the occurrence of the photoelectric effect at the p-n junction can be prevented. That is, the bidirectional Zener diode IZD of the third embodiment can also reduce the leak current flowing from the n-type semiconductor region NR to the p-type semiconductor region PR due to the photoelectric effect in the p-n junction. This means that, for example, the current passing through the light-emitting diode LED coupled in parallel to the bidirectional Zener diode IZD can be ensured to reduce the loss of the current. Since the leak current at the bidirectional Zener diode IZD can be reduced, the Zener diode IZD can improve the efficiency of use of current for emission of light from the light-emitting diode LED to thereby reduce the useless current not contributing to the light emission of the light-emitting diode LED. In this way, the bidirectional Zener diode IZD of the third embodiment can also reduce the leak current due to the photoelectric effect, and as a result, can improve the efficiency of use of current at the diode LED.
The bidirectional Zener diode IZD of the third embodiment has the structure described above, and a manufacturing method thereof is substantially the same as that of the first embodiment. Specifically, the steps shown in
Although the first to third embodiments have described the bidirectional Zener diode IZD, a fourth embodiment of the invention will describe an example of application of the invention to the Zener diode ZD. As described in the first embodiment, when using the light-emitting diodes LEDs coupled in the form of a matrix, the bidirectional Zener diode IZD for protecting the light-emitting diode LED from the surge voltage is desirably coupled in parallel to the corresponding light-emitting diode LED for the purpose of suppressing the sneak current. When using the single light-emitting diode LED, the sneak current is not generated, and thus the Zener diode ZD for protecting the diode LED from the surge voltage is supposed to be coupled in anti-parallel to the light-emitting diode LED. Thus, the light-emitting diode LED and the Zener diode ZD are proposed to be mounted in one package. In this case, the Zener diode ZD is also required to reduce the leak current due to the photoelectric effect. Thus, the technical ideas given in the description of the bidirectional Zener diodes IZDs of the first to third embodiments can be applied to the Zener diode ZD, too.
Now, the fourth embodiment of the invention will describe an example in which the invention is applied to the Zener diode ZD.
A pair of trenches TR is formed to reach the inside of the semiconductor substrate 1 through the n-type semiconductor region NR from the surface of the n-type semiconductor region NR. The region interposed between the pair of trenches TRs is an active region serving as the Zener diode ZD. That is, in the trench Zener diode ZD, the active region is isolated by the pair of the trenches TRs, and the Zener diode ZD is formed in the isolated active region.
A protective insulating film IF1 is formed over the surface of the n-type semiconductor region NR with such trenches TRs formed therein. Specifically, the protective insulating film IF1 is formed over the surface of the n-type semiconductor region NR including the inner walls of the trenches TRs. The protective insulating film IF1 is comprised of, for example, a silicon oxide film, a silicon nitride film, a PSG film which is a glassy film provided by adding phosphorus into a silicon oxide film, or the like.
An opening OP is formed in the protective insulating film IF1, and an upper electrode UE is formed over the protective insulating film IF1 including the opening OP. Specifically, the opening OP is formed in the active region interposed between the pair of trenches TRs. The n-type semiconductor region NR is exposed to the bottom of the opening OP. In the fourth embodiment, the upper electrode UE is formed to extend from the inside of the opening OP over the protective insulating film IF1 covering the inner walls of the trenches TRs. Thus, the upper electrode UE is brought into contact with the n-type semiconductor region NR exposed to the bottom of the opening OP. The upper electrode UE is comprised of a conductive film, such as a metal film or a metal compound film, for example, an aluminum-silicon film.
Also, in the fourth embodiment, the upper electrode UE extends from the inside of the opening OP to cover the trench TR (isolation region). That is, as shown in
Next, a modified example of the Zener diode ZD in the fourth embodiment will be described below.
The Zener diode ZD of the fourth embodiment has the structure described above, and a manufacturing method thereof will be described below with reference to the accompanying drawings. First, as shown in
Then, as shown in
Thereafter, as shown in
Then, as shown in
Subsequently, as shown in
And as shown in
Then, as shown in
As mentioned above, the Zener diode ZD of the fourth embodiment can be manufactured. In the Zener diode ZD of the fourth embodiment, the inner wall of each trench TR is covered with the upper electrode UE (light blocking film) having the light blocking effect. Even when the light is applied to the Zener diode ZD, the light can be prevented from entering the p-n junction formed at the boundary between the n-type semiconductor region NR and the semiconductor substrate 1S from the inner wall of the trench TR. Thus, according to the fourth embodiment, the leak current due to the photoelectric effect can be reduced.
A fifth embodiment of the invention will describe an example in which the inside of the trench TR is filled with a filling film.
Thus, the inside of the trench TR is filled with the polysilicon film PF1, so that the surface of the trench TR is aligned with the surface of the n-type semiconductor region NR. As a result, the flatness is improved over the surface of the trench TR filled with the polysilicon film PF1 and the surface of the n-type semiconductor region NR, which advantageously facilitates formation of the protective insulating film IF1 over the n-type semiconductor region NR including the trench TR.
Although the fifth embodiment has described an example in which the inside of the trench TR is filled with the polysilicon film via the insulating film IF2, only the insulating film may be embedded in the trench TR.
Also, in the Zener diode ZD of the fifth embodiment, like the Zener diode ZD of the fourth embodiment, the upper electrode UE extends from the inside of the opening OP to cover the trench TR (isolation region). Even when the light is applied to the Zener diode ZD, the light can be prevented from entering the p-n junction formed at the boundary between the n-type semiconductor region NR and the semiconductor substrate 1S from the inner wall of the trench TR. Thus, the occurrence of the photoelectric effect in the p-n junction can be suppressed. That is, the Zener diode ZD of the fifth embodiment can also reduce the leak current flowing from the n-type semiconductor region NR to the semiconductor substrate 1S due to the photoelectric effect in the p-n junction. This means that, for example, the current passing through the light-emitting diode coupled in anti-parallel to the Zener diode ZD can be ensured to thereby reduce the loss of the current. Since the leak current at the Zener diode ZD can be reduced, the Zener diode ZD can improve the efficiency of use of current for emission of light from the light-emitting diode LED to thereby reduce the useless current not contributing to the light emission of the light-emitting diode LED. In this way, the Zener diode ZD of the fifth embodiment can also reduce the leak current due to the photoelectric effect, and as a result, can improve the efficiency of use of current at the diode LED.
The Zener diode IZD of the fifth embodiment has the structure described above, and a manufacturing method thereof is substantially the same as that of the fourth embodiment. Specifically, steps shown in
A sixth embodiment of the invention will describe an example in which an isolation region is comprised of a semiconductor region.
As mentioned above, in the sixth embodiment, the isolation region is not formed from the trench TR, unlike the fourth and fifth embodiments, and thus formed from the p-type semiconductor region PR1. This has an advantage that the step for forming the trench TR can be omitted. Further, since no trench TR is formed, the surface of the n-type semiconductor region NR is aligned with the surface of the p-type semiconductor region PR1 serving as the isolation region, which advantageously facilitates the formation of the protective insulating film IF1 over the n-type semiconductor region NR including the p-type semiconductor region PR1 (isolation region).
In the Zener diode ZD of the sixth embodiment, like the Zener diode ZD of the fourth embodiment, the upper electrode UE extends from the inside of the opening OP to cover the isolation region (p-type semiconductor region PR1). Thus, even when light is applied to the Zener diode ZD, the light can be prevented from entering the p-n junction formed at the boundary between the p-type semiconductor region PR1 and the n-type semiconductor region NR, and the p-n junction formed at the boundary between the n-type semiconductor region NR and the semiconductor substrate 1S. Thus, the occurrence of the photoelectric effect in the p-n junction can be suppressed. This means that the current flowing through the light-emitting diode LED coupled in anti-parallel to the Zener diode ZD can be ensured to reduce the loss of current. Since the leak current at the Zener diode ZD can be reduced, the Zener diode ZD can improve the efficiency of use of current for emission of light from the light-emitting diode LED to thereby reduce the useless current not contributing to the light emission of the light-emitting diode LED. In this way, the Zener diode ZD of the sixth embodiment can also reduce the leak current due to the photoelectric effect, and as a result, can improve the efficiency of use of current at the diode LED.
The Zener diode ZD of the sixth embodiment has the structure described above, and a manufacturing method thereof is substantially the same as that of the fourth embodiment. Specifically, the steps shown in
The first to third embodiments have described the device structures of the bidirectional Zener diodes, and the fourth to sixth embodiments has described the device structures of the Zener diodes. The seventh embodiment will describe a package structure including the bidirectional Zener diode described in the first to third embodiments and the light-emitting diode which are mounted in one package, or a package structure including the Zener diode described in the fourth to sixth embodiments and the light-emitting diode which are mounted in one package.
The circuit shown in each of
For example, suppose that the surge voltage is applied to the light-emitting diode from the outside. In this case, the surge voltage is also applied to the bidirectional Zener diode (simply, the Zener diode) coupled in anti-parallel to the light-emitting diode. Thus, when the surge voltage exceeds the breakdown voltage of the bidirectional Zener diode (Zener diode), the breakdown of the bidirectional Zener diode (Zener diode) occurs to absorb the surge voltage, which is converted into a small Zener voltage. As a result, the only small Zener voltage is applied to the light-emitting diode, which can protect the light-emitting diode from the surge voltage.
The semiconductor chip CHP2 used in the seventh embodiment is provided with the bidirectional Zener diode of any one of the first to third embodiments, or the Zener diode of any one of the fourth to sixth embodiments. Thus, even when the semiconductor chip CHP2 is mounted together with the semiconductor chip CHP1 in one package, the leak current due to the photoelectric effect can be reduced in the semiconductor chip CHP2. This means that the current flowing through the light-emitting diode formed in the semiconductor chip CHP1 can be ensured to reduce the loss of current. Since the leak current due to the photoelectric effect can be reduced in the semiconductor chip CHP2, the efficiency of use of current for emission of light from the light-emitting diode formed in the semiconductor chip CHP1 can be improved to thereby lessen useless current not contributing to the light emission from the light-emitting diode LED. The semiconductor chip CHP1 and the semiconductor chip CHP2 are mounted in one package, so that the package PAC1 of the seventh embodiment can reduce its size. That is, the seventh embodiment can provide the package PAC1 that achieves both the low power consumption and the reduction in size.
Next, another package PAC2 (semiconductor device) of the seventh embodiment will be described below.
The circuit shown in each of
For example, suppose that the surge voltage is applied to the light-emitting diode from the outside. In this case, the surge voltage is also applied to the bidirectional Zener diode (Zener diode) coupled in anti-parallel to the light-emitting diode. Thus, when the surge voltage exceeds the breakdown voltage of the bidirectional Zener diode (Zener diode), the breakdown of the bidirectional Zener diode (Zener diode) occurs to absorb the surge voltage, which is converted into a small Zener voltage. As a result, the only small Zener voltage is applied to the light-emitting diode, which can protect the light-emitting diode from the surge voltage.
The semiconductor chip CHP2 used in the seventh embodiment is provided with the bidirectional Zener diode of any one of the first to third embodiments, or the Zener diode of any one of the fourth to sixth embodiments. Thus, even when the semiconductor chip CHP2 is mounted together with the semiconductor chip CHP1 in one package, the leak current due to the photoelectric effect can be reduced in the semiconductor chip CHP2. This means that the current passing through the light-emitting diode formed in the semiconductor chip CHP1 can be ensured to reduce the loss of the current. Since the leak current due to the photoelectric effect in the semiconductor chip CHP2 can be reduced, the efficiency of use of current for emission of light from the light-emitting diode formed in the chip CHP1 can be improved to thereby reduce the useless current not contributing to the light emission of the light-emitting diode. Since the semiconductor chip CHP1 and the semiconductor chip CHP2 are mounted in one package, the package PACT of the seventh embodiment can reduce its size. That is, the seventh embodiment can also provide the package PAC2 that achieves both the low power consumption and the reduction in size.
The following will describe a composite package (semiconductor device: moodule) CPAC1 including the above packages PAC2s coupled together in the form of a matrix.
The seventh embodiment has described the package PAC1 or package PAC2 in which the semiconductor chip CHP1 with the light-emitting diode formed therein, and the semiconductor chip CHP2 with the bidirectional Zener diode or Zener diode formed therein are mounted together. In the packages PAC1 and PAC2, the semiconductor chip CHP2 is coupled to the wiring or lead via the wire W2. The wire W2 possibly makes a shadow of light emitted from the light-emitting diode, which may reduce the efficiency of irradiation with light from the packages PAC1 and PAC2. The eighth embodiment will describe the device structure in which the semiconductor chip CHP2 with the bidirectional Zener diode formed therein can be coupled not by the wire W2, but by a bump electrode. As shown in a tenth embodiment, the semiconductor chips CHP2 of this embodiment are included in the packages PAC1 or packages PAC2 constituting the composite package (semiconductor device: moodule) CPAC1, shown in the seventh embodiment and in
Subsequently, the protective insulating film IF1 is formed over the surface of the p-type semiconductor region so as to cover the p-type semiconductor region (p-type semiconductor region PR1 and p-type semiconductor region PR2), the pair of trenches TR1s, and the pair of trenches TR2s. The protective insulating film IF1 is comprised of, for example, a silicon oxide film, a silicon nitride film, a PSG film which is a glassy film provided by adding phosphorus into a silicon oxide film, or the like. At the protective insulating film IF1, an opening OP1 for exposing a part of the p-type semiconductor region PR1 is formed in the first active region, and an opening OP2 for exposing a part of the p-type semiconductor region PR2 is formed in the second active region.
In the first active region, an under bump metal film UBM1 is formed over the protective insulating film IF1 including the opening OP1, and a bump electrode BMP1 is formed over the under bump metal film UBM1. In the second active region, an under bump metal film UBM2 is formed over the protective insulating film IF1 including the inside of the opening OP2, and a bump electrode BMP2 is formed over the under bump metal film UBM2. The under bump metal films UBM1 and UBM2 are comprised of, for example, a titanium (Ti) film or a molybdenum (Mo) film. The bump electrodes BMP1 and BMP2 are comprised of, for example, a gold film.
The feature of the eighth embodiment is that the under bump metal film UBM1 extends from the inside of the opening OP1 to cover the inner walls of a pair of trenches TR1s, and that the under bump metal film UBM2 extends from the inside of the opening OP2 to cover the inner walls of a pair of trenches TR2s.
The under bump metal films UBM1 and UBM2 are formed of a conductive film containing metal, for example, a titanium film or a molybdenum film, and has the light blocking effect. That is, in the bidirectional Zener diode IZD of the eighth embodiment, the inner wall of the trench TR1 is covered with the under bump metal film UBM1 having the light blocking effect, and the inner wall of the trench TR2 is covered with the under bump metal film UBM2 having the light blocking effect. Even when the light is applied to the bidirectional Zener diode IZD, the light can be prevented from entering the p-n junction formed at the boundary between the p-type semiconductor region PR1 and the semiconductor substrate 1S from the inner wall of the trench TR. Likewise, the light can be prevented from entering the p-n junction formed at the boundary between the p-type semiconductor region PR2 and the semiconductor substrate 1S from the inner wall of the trench TR2. Thus, the occurrence of the photoelectric effect at the p-n junction can be prevented.
That is, the bidirectional Zener diode IZD of the eighth embodiment can reduce the leak current at the p-n junction due to the photoelectric effect. This means that the current passing through the light-emitting diode LED coupled in parallel to the bidirectional Zener diode IZD can be ensured to reduce the loss of current. Since the leak current at the bidirectional Zener diode IZD can be reduced, the Zener diode IZD can improve the efficiency of use of current for emission of light from the light-emitting diode LED to thereby reduce the useless current not contributing to the light emission of the light-emitting diode LED. In this way, the bidirectional Zener diode IZD of the eighth embodiment can reduce the leak current due to the photoelectric effect, and as a result, can improve the efficiency of use of current at the diode LED.
Now, a modified example of the bidirectional Zener diode IZD of the eighth embodiment will be described below.
Such a structure can also prevent the light from entering the p-n junction formed at the boundary between the p-type semiconductor region PR1 and the semiconductor substrate 1S, and the p-n junction formed at the boundary between the p-type semiconductor region PR2 and the semiconductor substrate 1S, from the inner wall of the trench TR1 or the inner wall of the trench TR2. Thus, the occurrence of the photoelectric effect in the p-n junction can be suppressed. Unless the light is applied to the p-n junction within the first active region formed on the inner side of both sides of the trench TR1, the leak current due to the photoelectric effect can be reduced. Likewise, unless the light is applied to the p-n junction within the second active region formed on the inner side of both sides of the trench TR2, the leak current due to the photoelectric effect can be reduced.
From this point, in the bidirectional Zener diode IZD of the eighth embodiment, like the bidirectional Zener diode IZD shown in
Further, another modified example of the bidirectional Zener diode IZD of the eighth embodiment will be described below.
This arrangement can surely prevent light from being applied to the inside of the trench TR1 or TR2. As a result, the bidirectional Zener diode IZD of the modified example can reduce the leak current due to the photoelectric effect.
The bidirectional Zener diode IZD of the eighth embodiment has the structure described above, and a manufacturing method thereof will be described below with reference to the accompanying drawings.
First, as shown in
Then, as shown in
Subsequently, as shown in
As shown in
Thereafter, the under bump metal film UBM is formed over the p-type semiconductor region PR1 exposed from the opening OP1, the p-type semiconductor region PR2 exposed from the opening OP2, and the protective insulating film IF1. The under bump metal film UBM can be comprised of, for example, a titanium film or a molybdenum film. The film UBM can be formed, for example, by sputtering. In this step, the under bump metal film UBM is formed to cover the inner wall of the trench TR1 and the inner wall of the trench TR2.
Then, as shown in
Subsequently, as shown in
Then, the back side of the semiconductor substrate 1S is polished (back-ground) to make the semiconductor substrate 1S thinner.
In this way, the bidirectional Zener diode IZD of the eighth embodiment can be manufactured. In the bidirectional Zener diode IZD of the eighth embodiment, the inner wall of the trench TR1 is covered with the under bump metal film UBM1 (light blocking film) having the light blocking effect, and the inner wall of the trench TR2 is covered with the under bump metal film UBM2 (light blocking film) having the light blocking effect. Even when the light is applied to the bidirectional Zener diode IZD, the light can be prevented from entering the p-n junction from the inner wall of the trench TR. Thus, according to the eighth embodiment, the leak current due to the photoelectric effect can be reduced.
A ninth embodiment of the invention will describe a device structure which can couple a semiconductor chip with a Zener diode formed to a bump electrode.
Subsequently, a protective insulating film IF1 is formed over the surface of the p-type semiconductor region and the semiconductor substrate 1S to cover the semiconductor substrate 1S, the p-type semiconductor region (including the p-type semiconductor region PR1), the pair of trenches TR1s, and the pair of trenches TR2s. The protective insulating film IF1 is comprised of, for example, a silicon oxide film, a silicon nitride film, a PSG film which is a glassy film provided by adding phosphorus into a silicon oxide film, or the like. At the protective insulating film IF1, an opening OP1 for exposing a part of the p-type semiconductor region PR1 is formed in the first active region, and an opening OP2 for exposing a part of the semiconductor substrate 1S is formed in the second active region.
In the first active region, an under bump metal film UBM1 is formed over the protective insulating film IF1 including the opening OP1, and a bump electrode BMP1 is formed over the under bump metal film UBM1. In the second active region, an under bump metal film UBM2 is formed over the protective insulating film IF1 including the inside of the opening OP2, and a bump electrode BMP2 is formed over the under bump metal film UBM2. The under bump metal films UBM1 and UBM2 are comprised of, for example, a titanium (Ti) film or a molybdenum (Mo) film. The bump electrodes BMP1 and BMP2 are formed of, for example, a gold film.
The feature of the ninth embodiment is that the under bump metal film UBM1 is formed to extend from the inside of the opening OP1 and to cover the inner walls of a pair of trenches TR1s, and that the under bump metal film UBM2 is formed to extend from the inside of the opening OP2 and to cover the inner walls of a pair of trenches TR2s.
The under bump metal films UBM1 and UBM2 are comprised of a conductive film containing metal, for example, a titanium film or a molybdenum film, and has the light blocking effect. That is, in the Zener diode ZD of the ninth embodiment, the inner wall of the trench TR1 is covered with the under bump metal film UBM1 having the light blocking effect, and the inner wall of the trench TR2 is covered with the under bump metal film UBM2 having the light blocking effect. Even when the light is applied to the Zener diode ZD, the light can be prevented from entering the p-n junction formed at the boundary between the p-type semiconductor region PR1 and the semiconductor substrate 1S from the inner wall of the trench TR1. Thus, the occurrence of the photoelectric effect in the p-n junction can be suppressed.
That is, the Zener diode ZD of the ninth embodiment can reduce the leak current due to the photoelectric effect in the p-n junction. This means that the current passing through the light-emitting diode LED coupled in parallel to the Zener diode IZD can be ensured to thereby reduce the loss of current. Since the leak current at the Zener diode ZD can be reduced, the Zener diode IZD can improve the efficiency of use of current for emission of light from the light-emitting diode LED to thereby reduce the useless current not contributing to the light emission of the light-emitting diode LED. In this way, the Zener diode ZD of the ninth embodiment can reduce the leak current due to the photoelectric effect, and as a result, can improve the efficiency of use of current at the diode LED.
The inner wall of the trench TR2 may not be covered with the under bump metal film UBM2 having the light blocking effect. This is because only the semiconductor substrate 1S exists in the second active region, in which the p-n junction is not formed.
Next, a modified example of the Zener diode ZD of the ninth embodiment will be described below.
Also, with this arrangement, light can be prevented from entering the p-n junction formed at the boundary between the semiconductor substrate 1S and the p-type semiconductor region PR1 from the inner wall of the trench TR1. Thus, the occurrence of the photoelectric effect can be suppressed in the p-n junction. When the light is not applied to the p-n junction positioned in the first active region formed on the inner one of both sides of the trench TR1, the leak current due to the photoelectric effect can be reduced.
From this point, in the Zener diode ZD of the ninth embodiment, like the Zener diode ZD shown in
Further, another modified example of the Zener diode ZD of the ninth embodiment will be described below.
This can surely prevent the light from being applied to the insides of the trench TR1 and the trench TR2. As a result, the Zener diode ZD in the modified example can reduce the leak current due to the photoelectric effect.
The Zener diode ZD of the ninth embodiment has the structure described above, and a manufacturing method thereof is substantially the same as that of the eighth embodiment. Specifically, in the ninth embodiment, the p-type semiconductor region PR is not formed over the entire main surface of the semiconductor substrate 1S, unlike the embodiment shown in
The eighth embodiment has described the device structure of the bidirectional Zener diode with the bump electrodes formed therein, and the ninth embodiment has described the device structure of the Zener diode with the bump electrodes formed therein. The tenth embodiment has described a package structure including the bidirectional Zener diode described in the eighth embodiment and the light-emitting diode which are mounted in one package, or a package structure including the Zener diode described in the ninth embodiment and the light-emitting diode which are mounted in one package.
The circuit shown in each of
For example, suppose that the surge voltage is applied to the light-emitting diode from the outside. In this case, the surge voltage is also applied to the bidirectional Zener diode (simply, the Zener diode) coupled in anti-parallel to the light-emitting diode. Thus, when the surge voltage exceeds the breakdown voltage of the bidirectional Zener diode (Zener diode), the breakdown of the bidirectional Zener diode (Zener diode) occurs to absorb the surge voltage, which is converted into a small Zener voltage. As a result, the only small Zener voltage is applied to the light-emitting diode, which can protect the light-emitting diode from the surge voltage.
The semiconductor chip CHP2 used in the tenth embodiment is provided with the bidirectional Zener diode of the eighth embodiment, or the Zener diode of the ninth embodiment. Thus, even when the semiconductor chip CHP2 is mounted together with the semiconductor chip CHP1 in one package, the leak current due to the photoelectric effect can be reduced in the semiconductor chip CHP2. This means that the current passing through the light-emitting diode formed in the semiconductor chip CHP1 can be ensured to reduce the loss of current. Since the leak current due to the photoelectric effect in the semiconductor chip CHP2 can be reduced, the light-emitting diode can improve the efficiency of use of current for emission of light from the diode formed in the semiconductor chip CHP1 to thereby reduce the useless current not contributing to the light emission of the light-emitting diode. Since the semiconductor chip CHP1 and the semiconductor chip CHP2 are mounted in one package, the package PAC3 of the tenth embodiment can reduce its size. That is, the tenth embodiment can provide the package PAC3 that achieves both the low power consumption and the reduction in size.
Further, the feature of the package PAC3 of the tenth embodiment is that the semiconductor chip CHP2 with the bidirectional Zener diode or Zener diode formed therein is coupled to the wiring WL2 via the bump electrode BMP1, and to the wiring WL1 via the bump electrode BMP2. That is, in the package PAC3 of the tenth embodiment, the semiconductor chip CHP2 is coupled to the wiring (wiring WL1 and wiring WL2) via the bump electrodes (bump electrode BMP1 and bump electrode BMP2) and not via the wire. Thus, since there is no wire that makes a shadow of light generated from the light-emitting diode, the efficiency of irradiation with the light from the package PAC3 can be improved. The packages PAC3 are included in the composite package (semiconductor device: moodule) CPAC1, shown in the seventh embodiment and in
Although the invention made by the inventors has been specifically described based on the embodiments, the invention is not limited to the embodiments disclosed therein. It is apparent that various modifications can be made without departing from the scope and spirit of the invention.
The invention can be applied to a case where a conduction type of the bidirectional Zener diode or Zener diode described in the above embodiments is reversed. Specifically, the invention can also be applied to another device structure (a package structure, module) in which the p-type semiconductor region of the diode described in the above embodiment is changed to an n-type semiconductor region, and the n-type semiconductor region is changed to a p-type semiconductor region.
The invention can be widely used to manufacturing industries for manufacturing semiconductor devices. The invention can be widely used to an apparatus including a diode affected by the photoelectric effect. The apparatus includes a display device, such as the LED display, for example.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-262797 | Nov 2009 | JP | national |
