HIGH VOLTAGE JUNCTION FIELD EFFECT TRANSISTOR
Provided is a semiconductor device, including: a substrate, a well region of a first conductivity type, a field region of a second conductivity type, a first doped region of the first conductivity type, and a second doped region of the second conductivity type. The well region is located in the substrate. The field region is located in the well region. The first doped region is located in the well region of a first side of the field region. The second doped region is located in the field region, wherein the first doped region is at least partially surrounded by the second doped region.
[Field of the Invention]
The invention relates to a semiconductor device and particularly relates to a high voltage junction field effect transistor (JFET).
[Description of Related Art]
High voltage devices are extensively used in power management integrated circuits (PMIC), switch mode power supplies (SMPS), and LED drivers. In recent years, green energy technology, which requires higher conversion efficiency and lower standby power consumption, is drawing more and more attention. Generally, a start-up circuit and a pulse width modulation (PWM) circuit are integrated in a switch mode power integrated circuit. The start-up circuit can be used for starting up the pulse width modulation circuit and is turned off when the pulse width modulation circuit is started up and begins to operate. Thus, the start-up circuit needs to have the characteristic of low leakage current.
Compared to the conventional power resistor or high voltage depletion NMOS (HVDNMOS), a high voltage junction field effect transistor (HVJFET) is used as the start-up circuit, which has the characteristics of high pinch off voltage and low leakage current. However, the traditional HVJFET requires a well region so as to pinch off voltage and the well is more sensitive to the process variation. As a result, the pinch off voltage may shift easily.
SUMMARY OF THE INVENTIONThe invention provides a semiconductor device with reduced sensitivity to process variation for stabilizing electrical properties.
The invention provides a semiconductor device, including: a substrate, a well region of a first conductivity type, a field region of a second conductivity type, a first doped region of the first conductivity type, and a second doped region of the second conductivity type. The well region is disposed in the substrate. The field region is disposed in the well region. The first doped region is disposed in the well region on a first side of the field region. The second doped region is disposed in the field region, wherein the second doped region at least partially surrounds the first doped region.
In an embodiment of the invention, the field region and the second doped region overlap each other, and the field region surrounds the second doped region.
In an embodiment of the invention, the second doped region further extends to surround the first doped region.
In an embodiment of the invention, the second doped region is one doped region or includes a plurality of doped regions.
In an embodiment of the invention, the second doped region includes a plurality of doped regions. The doped regions are arranged symmetrically or asymmetrically with respect to the first doped region.
In an embodiment of the invention, the semiconductor device further includes: a third doped region of the first conductivity type, a first top doped region of the second conductivity type, a plurality of second top doped regions of the second conductivity type, and a fourth doped region of the second conductivity type. The third doped region is disposed in the well region on a second side of the field region. The field region is disposed between the first doped region and the third doped region. The first top doped region is disposed between the third doped region and the second doped region. The second top doped regions are disposed in the well region between the field region and the first doped region. The fourth doped region is disposed in the substrate on the second side of the field region. The third doped region is disposed between the first top doped region and the fourth doped region.
In an embodiment of the invention, the first top doped region and the third doped region partially overlap each other.
In an embodiment of the invention, the first doped region is annular, and the second top doped regions surround the first doped region.
In an embodiment of the invention, the first doped region is a drain, the second doped region is a gate, the third doped region is a source, and the fourth doped region is a base gate.
The invention provides a semiconductor device, including: a substrate of a second conductivity type, a first well region of a first conductivity type, a first field region of the second conductivity type, a first doped region of the first conductivity type, a second doped region of the second conductivity type, a third doped region of the first conductivity type, a first top doped region of the second conductivity type, and a first insertion layer of the first conductivity type. The first well region is disposed in the substrate. The first field region is disposed in the first well region. The first doped region is disposed in the first well region on a first side of the first field region. The second doped region is disposed in the first field region. The third doped region is disposed in the first well region on a second side of the first field region. The second doped region is disposed between the first doped region and the third doped region. The first top doped region is disposed in the first well region under the first field region. The first insertion layer is disposed above a portion of the first field region. The portion of the first field region is disposed between the first insertion layer and the first top doped region.
In an embodiment of the invention, the first field region, the first top doped region and the first insertion layer, and the third doped region partially overlap one another.
In an embodiment of the invention, the first field region surrounds the second doped region, and the first field region and the second doped region overlap each other.
In an embodiment of the invention, the semiconductor device further includes: an isolation structure, a second top doped region of the second conductivity type, and a second insertion layer of the first conductivity type. The isolation structure is disposed between the first doped region and the second doped region. The second top doped region is disposed in the first well region under the isolation structure. The second insertion layer is disposed between the isolation structure and the second top doped region.
In an embodiment of the invention, the isolation structure includes a field oxide structure, a shallow trench isolation structure, a deep trench isolation structure, or a combination of the foregoing.
In an embodiment of the invention, the semiconductor device further includes: a second well region of the second conductivity type, a second field region of the second conductivity type, and a fourth doped region of the second conductivity type. The second well region is disposed in the substrate on the second side of the first field region. The second field region is disposed in the second well region. The fourth doped region is disposed in the second field region.
In an embodiment of the invention, a distance exists between the first field region and the second field region. A length of the distance is in a range of 1 μm to 18 μm.
In an embodiment of the invention, the first doped region is a drain, the second doped region is a gate, the third doped region is a source, and the fourth doped region is a base gate.
In an embodiment of the invention, the first well region includes a deep well region, a drift layer, a buffer layer, or a combination of the foregoing.
In an embodiment of the invention, the substrate includes an epitaxial layer, a non-epitaxial layer, a silicon on insulator substrate, or a combination of the foregoing.
In an embodiment of the invention, the semiconductor device further includes a buried layer of the first conductivity type disposed between the first well region and the substrate.
Based on the above, the invention replaces the well region of the conventional HVJFET with the first field region and the first top doped region having a shallower doping depth, so as to reduce the sensitivity of the HVJFET to the process variation. Moreover, because the first field region and the first top doped region and the third doped region (the source, for example) partially overlap one another, the first field region and the first top doped region may serve as the pinch off channel under the source for stabilizing the electrical properties. In addition, the invention includes one or more second doped regions (the gate, for example) to at least partially surround the first doped region (the drain, for example) so as to adjust the drain current.
To make the aforementioned and other features and advantages of the invention more comprehensible, several embodiments accompanied with drawings are described in detail as follows.
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the invention and, together with the description, serve to explain the principles of the invention.
In the following embodiments, if a first conductivity type is N-type, a second conductivity type is P-type; and if the first conductivity type is P-type, the second conductivity type is N-type. A P-type dopant is boron, for example; and an N-type dopant is phosphorus or arsenic, for example. In this embodiment, the first conductivity type is N-type and the second conductivity type is P-type, for example. However, it should be noted that the invention is not limited thereto. Hereinafter, the same or similar reference numerals represent the same or similar elements.
With reference to
The well region 102 is located in the substrate 100. Although
The second doped region 112 is located in the field region 104. That is, the second doped region 112 overlaps the field region 104, and the field region 104 surrounds the second doped region 112.
It should be noted that, in some embodiments, the second doped region 112 is curved, for example, and at least a portion thereof surrounds a side of the first doped region 110, as shown in
Moreover, in some embodiments, the semiconductor device 1 further includes: a third doped region 114 of the first conductivity type, a top doped region 106 of the second conductivity type, and a fourth doped region 124 of the second conductivity type. The third doped region 114 is located in the well region 102 on the second side S2 of the top doped regions 116, wherein the second doped region 112 is located between the top doped regions 116 and the third doped region 114. The top doped region 106 is located between the third doped region 114 and the second doped region 112. The top doped region 106 partially overlaps the third doped region 114. The fourth doped region 124 is located in the substrate 100 on the second side S2 of the top doped regions 116. The third doped region 114 is located between the top doped region 106 and the fourth doped region 124. The fourth doped region 124 surrounds the third doped region 114. In an embodiment, the first doped region 110 is a drain, the second doped region 112 is a gate, the third doped region 114 is a source, and the fourth doped region 124 is a base gate, for example. Because the field region 104 and the top doped region 106 partially overlap the third doped region 114 (the source, for example), the field region 104 and the top doped region 106 may serve as a pinch off channel under the source for stabilizing the electrical properties.
With reference to
With reference to
The well region 102 is located in the substrate 100. In an embodiment, a dopant implanted into the well region 102 is phosphorus or arsenic, and a doping concentration thereof is in a range of 8×1013/cm3 to 8×1016/cm3, for example. In an embodiment, the well region 102 is a deep well region, a drift layer, a buffer layer, or a combination of the foregoing, for example. The field region 104 is located in the well region 102. In an embodiment, a dopant implanted into the field region 104 is boron, and a doping concentration thereof is in a range of 4×1014/cm3 to 8×1017/cm3 and a doping depth thereof is in a range of 0.4 μm to 1.8 μm, for example.
The first doped region 110 is located in the well region 102 on a first side S3 of the field region 104. In an embodiment, a dopant implanted into the first doped region 110 is phosphorus or arsenic, and a doping concentration thereof is in a range of 8×1016/cm3 to 8×1019/cm3, for example. The third doped region 114 is located in the well region 102 on a second side S4 of the field region 104. In an embodiment, a dopant implanted into the third doped region 114 is phosphorus or arsenic, and a doping concentration thereof is in a range of 8×1016/cm3 to 8×1019/cm3, for example. The second doped region 112 is located between the first doped region 110 and the third doped region 114 and located in the field region 104. Specifically, the second doped region 112 overlaps the field region 104, and the second doped region 112 is surrounded by the field region 104. In an embodiment, a dopant implanted into the second doped region 112 is boron, and a doping concentration thereof is in a range of 8×1016/cm3 to 8×1019/c m3, for example.
In an embodiment, the top doped region 106 and the insertion layer 108 may be optionally formed. In other words, a semiconductor device not including the top doped region 106 and the insertion layer 108 also falls within the scope of the invention. The field region 104, the top doped region 106 and the insertion layer 108 partially overlap the third doped region 114 and the field region 104, the top doped region 106 and the insertion layer 108 are located in the well region 102. More specifically, the top doped region 106 is located under a portion of the field region 104. In an embodiment, the top doped region 106 may also extend under the second doped region 112. In an embodiment, a dopant implanted into the top doped region 106 is boron, and a doping concentration thereof is in a range of 1×1014/cm3 to 8×1017/cm3 and a doping depth thereof is in a range of 0.4 μm to 1.8 μm, for example. The insertion layer 108 is located above a portion of the field region 104. A portion of the field region 104 is located between the insertion layer 108 and the top doped region 106. In an embodiment, a dopant implanted into the insertion layer 108 is phosphorus or arsenic, and a doping concentration thereof is in a range of 2×1014/cm3 to 2×1017/cm3 and a doping depth thereof is in a range of 0.3 μm to 1.2 μm, for example. In an embodiment, the first doped region 110 is a drain D, the second doped region 112 is a gate G, the third doped region 114 is a source S, and the fourth doped region 124 is a base gate B, for example.
It should be noted that because the field region 104 and the top doped region 106 partially overlap the third doped region 114 (the source S, for example), the field region 104 and the top doped region 106 may serve as the pinch off channel under the source for stabilizing the electrical properties. Moreover, the insertion layer 108 and the third doped region 114 (the source S, for example) also partially overlap and are in contact with each other. Therefore, the drain current is allowed to flow through the insertion layer 108 (the current channel, for example) having a shallower doping depth. Since the insertion layer 108 has the shallower doping depth, the insertion layer 108 is less likely to be affected by the process variation (the drive in temperature or ion implantation process, for example) in comparison with the well region that has a deeper doping depth. Thereby, the invention prevents the pinch off voltage from shifting due to the process variation.
Moreover, in some embodiments, the semiconductor device 3 further includes: isolation structures 10 and 20, a top doped region 116 of the second conductivity type, an insertion layer 118 of the first conductivity type, a well region 120 of the second conductivity type, a field region 122 of the second conductivity type, and a fourth doped region 124 of the second conductivity type. The isolation structure 10 includes isolation structures 10a, 10b, and 10c. As shown in
The top doped region 116 is located in the well region 102 under the isolation structure 10c. The top doped region 116 has an effect of reduced surface field (RESURF), thereby improving the breakdown voltage of the semiconductor device 3. In an embodiment, a dopant implanted into the top doped region 116 is boron, and a doping concentration thereof is in a range of 1×1014/cm3 to 8×1017/cm3, for example. The insertion layer 118 is located between the isolation structure 10c and the top doped region 116. The insertion layer 118 may serve as another current channel for reducing the ON resistance of the semiconductor device 3. In an embodiment, a dopant implanted into the insertion layer 118 is phosphorus or arsenic, and a doping concentration thereof is in a range of 2×1014/cm3 to 2×1017/cm3, for example. In an embodiment, the top doped region 116 and the insertion layer 118 may be optionally formed. In other words, a semiconductor device not including the top doped region 116 and the insertion layer 118 also falls within the scope of the invention.
In addition, the well region 120 is located in the substrate 100 on the second side S4 of the field region 104. In an embodiment, a dopant implanted into the well region 120 is boron, and a doping concentration thereof is in a range of 8×1014/cm3 to 4×1017/cm3, for example. The field region 122 is located in the well region 120. In an embodiment, a dopant implanted into the field region 122 is boron, and a doping concentration thereof is in a range of 4×1014/cm3 to 8×1017/cm3 and a doping depth thereof is in a range of 0.4 μm to 1.8 μm, for example. The fourth doped region 124 is located in the field region 122. In an embodiment, a dopant implanted into the fourth doped region 124 is boron, and a doping concentration thereof is in a range of 8×1016/cm3 to 8×1019/cm3, for example. It should be noted that a distance exists between the field region 104 and the field region 122. In an embodiment, a length L of the distance is in a range of 1 μm to 18 μm, for example. In this embodiment, the pinch off voltage is adjustable by changing the length L of the distance.
With reference to
To sum up, the invention replaces the well region of the conventional HVJFET with the first field region and the first top doped region having a shallower doping depth, so as to reduce the sensitivity of the HVJFET to the process variation. Moreover, because the first field region and the first top doped region and the third doped region (the source, for example) partially overlap one another, the first field region and the first top doped region may serve as the pinch off channel under the source for stabilizing the electrical properties. In addition, the invention includes one or more second doped regions (the gate, for example) to at least partially surround the first doped region (the drain, for example) so as to adjust the drain current.
It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed embodiments without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the invention covers modifications and variations of this disclosure provided that they fall within the scope of the following claims and their equivalents.
Claims
1. A semiconductor device, comprising:
- a well region of a first conductivity type disposed in a substrate;
- a field region of a second conductivity type disposed in the well region;
- a first doped region of the first conductivity type disposed in the well region on a first side of the field region;
- a second doped region of the second conductivity type disposed in the field region, wherein the second doped region at least partially surrounds the first doped region;
- a third doped region of the first conductivity type disposed in the well region on a second side of the field region, wherein the field region is disposed between the first doped region and the third doped region;
- a first top doped region of the second conductivity type disposed between the third doped region and the second doped region;
- a plurality of second top doped regions of the second conductivity type disposed in the well region between the field region and the first doped region; and
- a fourth doped region of the second conductivity type disposed in the substrate on the second side of the field region, wherein the third doped region is disposed between the first top doped region and the fourth doped region.
2. The semiconductor device according to claim 1, wherein the field region and the second doped region overlap each other, and the field region surrounds the second doped region.
3. The semiconductor device according to claim 1, wherein the second doped region further extends to surround the first doped region.
4. The semiconductor device according to claim 1, wherein the second doped region is one doped region or comprises a plurality of doped regions.
5. The semiconductor device according to claim 1, wherein the second doped region comprises a plurality of doped regions that are arranged symmetrically or asymmetrically with respect to the first doped region.
6. (canceled)
7. The semiconductor device according to claim 1, wherein the first top doped region and the third doped region partially overlap each other.
8. The semiconductor device according to claim 1, wherein the first doped region is a drain, the second doped region is a gate, the third doped region is a source, and the fourth doped region is a base gate.
9. The semiconductor device according to claim 1, wherein the first doped region is annular, and the second top doped regions surround the first doped region.
10. A semiconductor device, comprising:
- a first well region of a first conductivity type disposed in a substrate of a second conductivity type;
- a first field region of the second conductivity type disposed in the first well region;
- a first doped region of the first conductivity type disposed in the first well region on a first side of the first field region;
- a second doped region of the second conductivity type disposed in the first field region;
- a third doped region of the first conductivity type disposed in the first well region on a second side of the first field region, wherein the second doped region is disposed between the first doped region and the third doped region;
- a first top doped region of the second conductivity type disposed in the first well region under the first field region; and
- a first insertion layer of the first conductivity type disposed above a portion of the first field region, wherein the portion of the first field region is disposed between the first insertion layer and the first top doped region.
11. The semiconductor device according to claim 10, wherein the first field region, the first top doped region and the first insertion layer, and the third doped region partially overlap one another.
12. The semiconductor device according to claim 10, wherein the first field region surrounds the second doped region, and the first field region and the second doped region overlap each other.
13. The semiconductor device according to claim 10, further comprising:
- an isolation structure disposed between the first doped region and the second doped region;
- a second top doped region of the second conductivity type disposed in the first well region under the isolation structure; and
- a second insertion layer of the first conductivity type disposed between the isolation structure and the second top doped region.
14. The semiconductor device according to claim 13, wherein the isolation structure comprises a field oxide structure, a shallow trench isolation structure, a deep trench isolation structure, or a combination of the foregoing.
15. The semiconductor device according to claim 10, further comprising:
- a second well region of the second conductivity type disposed in the substrate on the second side of the first field region;
- a second field region of the second conductivity type disposed in the second well region; and
- a fourth doped region of the second conductivity type disposed in the second field region.
16. The semiconductor device according to claim 15, wherein a distance exists between the first field region and the second field region, and a length of the distance is in a range of 1 μm to 18 μm.
17. The semiconductor device according to claim 15, wherein the first doped region is a drain, the second doped region is a gate, the third doped region is a source, and the fourth doped region is a base gate.
18. The semiconductor device according to claim 10, wherein the first well region comprises a deep well region, a drift layer, a buffer layer, or a combination of the foregoing.
19. The semiconductor device according to claim 10, wherein the substrate comprises an epitaxial layer, a non-epitaxial layer, a silicon on insulator substrate, or a combination of the foregoing.
20. The semiconductor device according to claim 10, further comprising an buried layer of the first conductivity type disposed between the first well region and the substrate.
Type: Application
Filed: Jul 1, 2015
Publication Date: Jan 5, 2017
Inventors: Wing-Chor Chan (Hsinchu), Hsing-Chih Wu (Hsinchu)
Application Number: 14/789,478