Semiconductor device
View Patent ↗As a discrete semiconductor chip, there has been known one that enables flip-chip mounting by providing first and second electrodes in a current path above a first surface of a semiconductor substrate. However, there is a problem that a horizontal current flow in the substrate increases resistance components. A first electrode and a second electrode, which are connected to an element region, are provided above a first surface. Moreover, a thick metal layer having corrosion resistance and oxidation resistance and also having a low resistance is provided above a second surface. Thus, resistance components of a current flowing in a horizontal direction of a substrate are reduced. Moreover, by appropriately selecting a thickness of the thick metal layer, a resistance value of a device can be reduced while suppressing a cost increase. Furthermore, by adopting Au as the thick metal layer, defects such as discoloration of the thick metal layer with time can be prevented.
1. A semiconductor device comprising:
a semiconductor substrate comprising a first surface and a second surface;
a discrete semiconductor element formed in the semiconductor substrate;
a first electrode and a second electrode that are disposed on the first surface and connected with the discrete semiconductor element;
a first metal layer formed on the second surface so as to form an uppermost layer covering the second surface; and
a second metal layer disposed between the first metal layer and the second surface of the semiconductor substrate,
wherein the semiconductor device comprises a current path configured so that a current flows from the first electrode to first and second metal layers through the semiconductor substrate, flows along the first and second metal layers, and flows from the first and second metal layers to the second electrode through the semiconductor substrate upon application of voltages to the first and second electrodes,
the first metal layer is thicker than the second metal layer, and
the first metal layer has a higher degree of corrosion resistance or oxidation resistance than the second metal layer.
2. A semiconductor device comprising:
a semiconductor substrate comprising a first surface and a second surface;
a discrete semiconductor element formed in the semiconductor substrate;
a first electrode and a second electrode that are disposed on the first surface and connected with the discrete semiconductor element;
a first metal layer formed on the second surface so as to form an uppermost layer covering the second surface;
a second metal layer disposed between the first metal layer and the second surface of the semiconductor substrate; and
a third metal layer disposed between the second metal layer and the first metal layer,
wherein the semiconductor device comprises a current path configured so that a current flows from the first electrode to first, second and third metal layers through the semiconductor substrate, flows along the first, second and third metal layers, and flows from the first, second and third metal layers to the second electrode through the semiconductor substrate upon application of voltages to the first and second electrodes,
the first metal layer is thinner than the third metal layer, and
the first metal layer has a higher degree of corrosion resistance or oxidation resistance than the third metal layer.
3. The semiconductor device of claim 1 , wherein the first metal layer comprises gold.
4. A semiconductor device comprising:
a semiconductor substrate comprising a first surface and a second surface;
a discrete semiconductor element formed in the semiconductor substrate;
a first electrode and a second electrode that are disposed on the first surface and connected with the discrete semiconductor element;
a first metal layer formed on the second surface so as to form an uppermost layer covering the second surface;
a second metal layer disposed between the first metal layer and the second surface of the semiconductor substrate; and
a third metal layer disposed between the second metal layer and the first metal layer,
wherein a current path is configured to be formed between the first and second electrodes through the semiconductor substrate and the first, second and third metal layers upon application of voltages to the first and second electrodes,
the first metal layer is thinner than the third metal layer,
the first metal layer has a higher degree of corrosion resistance or oxidation resistance than the third metal layer, and
the first metal layer comprises gold, and the third metal layer comprises copper.
5. A semiconductor device comprising:
a semiconductor substrate comprising a first surface and a second surface;
a discrete semiconductor element formed in the semiconductor substrate;
a first electrode and a second electrode that are disposed on the first surface and connected with the discrete semiconductor element;
a first metal layer formed on the second surface so as to form an uppermost layer covering the second surface; and
a second metal layer disposed between the first metal layer and the second surface of the semiconductor substrate,
wherein a current path is configured to be formed between the first and second electrodes through the semiconductor substrate and the first and second metal layers upon application of voltages to the first and second electrodes,
the first metal layer is thicker than the second metal layer,
the first metal layer has a higher degree of corrosion resistance or oxidation resistance than the second metal layer, and
a thickness of the first metal layer corresponds to a saturation limit at which a resistance against the current path is no longer significantly reduced upon increasing the thickness of the first metal layer.
6. A semiconductor device comprising:
a semiconductor substrate comprising a first surface and a second surface;
a discrete semiconductor element formed in the semiconductor substrate;
a first electrode and a second electrode that are disposed on the first surface and connected with the discrete semiconductor element;
a first metal layer formed on the second surface so as to form an uppermost layer covering the second surface;
a second metal layer disposed between the first metal layer and the second surface of the semiconductor substrate; and
a third metal layer disposed between the second metal layer and the first metal layer,
wherein a current path is configured to be formed between the first and second electrodes through the semiconductor substrate and the first, second and third metal layers upon application of voltages to the first and second electrodes,
the first metal layer is thinner than the third metal layer,
the first metal layer has a higher degree of corrosion resistance or oxidation resistance than the third metal layer, and
a thickness of the third metal layer corresponds to a saturation limit at which a resistance against the current path is no longer significantly reduced upon increasing the thickness of the third metal layer.
7. The semiconductor device of claim 1 , wherein a thickness of the first metal layer is 5000 Å to 20000 Å.
8. The semiconductor device of claim 2 , wherein a thickness of the third metal layer is 5000 Å to 20000 Å.
9. The semiconductor device of claim 1 , wherein the discrete semiconductor element comprises a field-effect transistor, a bipolar transistor or a diode.
10. The semiconductor device of claim 2 , wherein the discrete semiconductor element comprises a field-effect transistor, a bipolar transistor or a diode.
11. A semiconductor device comprising:
a semiconductor substrate comprising a first surface and a second surface;
a first discrete semiconductor element of insulating gate type formed in the semiconductor substrate;
a second discrete semiconductor element of insulating gate type formed in the semiconductor substrate;
a drain region that is part of the substrate and operates as a drain common to the first and second discrete semiconductor elements;
a first source electrode and a second source electrode that are disposed on the first surface and connected with the first and second discrete semiconductor elements, respectively;
a first metal layer formed on the second surface so as to form an uppermost layer covering the second surface; and
a second metal layer disposed between the first metal layer and the second surface of the semiconductor substrate,
wherein the semiconductor device comprises a current path configured so that a current flows from the first source electrode to first and second metal layers through the semiconductor substrate, flows along the first and second metal layers, and flows from the first and second metal layers to the second source electrode through the semiconductor substrate upon application of voltages to the first and second electrodes,
the first metal layer is thicker than the second metal layer, and
the first metal layer has a higher degree of corrosion resistance or oxidation resistance than the second metal layer.
12. A semiconductor device comprising:
a semiconductor substrate comprising a first surface and a second surface;
a first discrete semiconductor element of insulating gate type formed in the semiconductor substrate;
a second discrete semiconductor element of insulating gate type formed in the semiconductor substrate;
a drain region that is part of the substrate and operates as a drain common to the first and second discrete semiconductor elements;
a first source electrode and a second source electrode that are disposed on the first surface and connected with the first and second discrete semiconductor elements, respectively;
a first metal layer formed on the second surface so as to form an uppermost layer covering the second surface;
a second metal layer disposed between the first metal layer and the second surface of the semiconductor substrate; and
a third metal layer disposed between the second metal layer and the first metal layer,
wherein the semiconductor device comprises a current path configured so that a current flows from the first source electrode to first, second and third metal layers through the semiconductor substrate, flows along the first, second and third metal layers, and flows from the first, second and third metal layers to the second source electrode through the semiconductor substrate upon application of voltages to the first and second electrodes,
the first metal layer is thinner than the third metal layer, and
the first metal layer has a higher degree of corrosion resistance or oxidation resistance than the third metal layer.
13. The semiconductor device of claim 11 , wherein the first metal layer comprises gold.
14. A semiconductor device comprising:
a semiconductor substrate comprising a first surface and a second surface;
a first discrete semiconductor element of insulating gate type formed in the semiconductor substrate;
a second discrete semiconductor element of insulating gate type formed in the semiconductor substrate;
a drain region that is part of the substrate and operates as a drain common to the first and second discrete semiconductor elements;
a first source electrode and a second source electrode that are disposed on the first surface and connected with the first and second discrete semiconductor elements, respectively;
a first metal layer formed on the second surface so as to form an uppermost layer covering the second surface;
a second metal layer disposed between the first metal layer and the second surface of the semiconductor substrate; and
a third metal layer disposed between the second metal layer and the first metal layer,
wherein a current path is configured to be formed between the first and second source electrodes through the semiconductor substrate and the first, second and third metal layers upon application of voltages to the first and second source electrodes,
the first metal layer is thinner than the third metal layer,
the first metal layer has a higher degree of corrosion resistance or oxidation resistance than the third metal layer, and
the first metal layer comprises gold, and the third metal layer comprises copper.
15. The semiconductor device of claim 1 , wherein a voltage applied to the first electrode is different from a voltage applied to the second electrode.