LATERAL DOUBLE DIFFUSED METAL-OXIDE-SEMICONDUCTOR DEVICE AND METHOD FOR FABRICATING THE SAME
A LDMOS device includes a substrate having opposite first and second surfaces; a well region in a portion of the substrate; a gate structure over a portion of the substrate; a first doped region disposed in a portion of the well region from a first side; a second doped region disposed in the well region from a second side; a third doped region disposed in the first doped region; a fourth doped region disposed in the second doped region; a first trench in the third doped region, the first doped region, the well region, and the substrate adjacent to the first surface; a conductive contact in the first trench; a second trench in the substrate adjacent to the second surface; a first conductive layer in second trench; and a second conductive layer over the second surface of the substrate and the first conductive layer.
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1. Field of the Invention
The present invention relates to integrated circuit (IC) devices, and in particular to a lateral double diffused metal-oxide-semiconductor (LDMOS) device and a method for fabricating the same.
2. Description of the Related Art
Recently, due to the rapid development of communication devices such as mobile communication devices and personal communication devices, wireless communication products such as mobile phones and base stations have been developed greatly. In wireless communication products, high-voltage elements of lateral double diffused metal-oxide-semiconductor (LDMOS) devices are often used as radio frequency (900 MHz-2.4 GHz) related elements therein.
LDMOS devices not only have a higher operation frequency, but they are also capable of sustaining a higher breakdown voltage, thereby having a high output power so that they can be used as power amplifiers in wireless communication products. In addition, due to the fact that LDMOS devices can be formed by conventional CMOS fabrications, LDMOS devices can be fabricated from a silicon substrate which is relatively cost-effective and employs mature fabrication techniques.
In
During operation of the N type LDMOS device shown in
Accordingly, an improved lateral double diffused metal oxide semiconductor (LDMOS) device and method for fabricating the same are provided to reduce size and fabrication cost.
An exemplary lateral double diffused metal oxide semiconductor (LDMOS) device comprises: a semiconductor substrate, having opposite first and second surfaces and a first conductivity type; a well region formed in a portion of the semiconductor substrate adjacent to the first surface thereof, having the first conductivity type; a gate structure disposed over a portion of the first surface of the semiconductor substrate; a first doped region disposed in a portion of the well region adjacent to a first side of the gate structure, having the first conductivity type; a second doped region disposed in a portion of the well region adjacent to a second side of the gate structure opposite to the first side, having a second conductivity type opposite to the first conductivity type; a third doped region disposed in a portion of the first doped region, having the second conductivity type; a fourth doped region disposed in a portion of the second doped region, having the second conductivity type; a first trench formed in a portion of the third doped region, the first doped region, the well region, and the semiconductor substrate; a conductive contact formed in the first trench; a second trench formed in a portion of the semiconductor substrate adjacent to the second surface thereof, wherein the second trench exposes a portion of the conductive contact; a first conductive layer formed in second trench, contacting the conductive contact; and a second conductive layer formed over the second surface of the semiconductor substrate and the first conductive layer.
An exemplary method for fabricating a lateral double diffused metal oxide semiconductor (LDMOS) device comprises: performing a semiconductor substrate, having opposite first and second surfaces and a first conductivity type; performing an ion implantation process, forming a well region in a portion of the semiconductor substrate adjacent to the first surface thereof, having the first conductivity type; forming a gate structure over a portion of the well region; forming a first doped region in a portion of the well region adjacent to a first side of the gate structure, having the first conductivity type; forming a second doped region in a portion of the well region at a second side of the gate structure opposite to the first side, having a second conductivity type opposite to the first conductivity type; forming a third doped region in a portion of the first doped region, having the second conductivity type; forming a fourth doped region in a portion of the second doped region, having the second conductivity type; forming a trench in a portion of the third doping region, the first doped region, the well region, and the semiconductor substrate; forming a conductive contact in the first trench; thinning the semiconductor substrate from the second surface thereof; after thinning the semiconductor substrate, forming a second trench in a portion of the semiconductor substrate adjacent to the second surface thereof, exposing a portion of the conductive contact; forming a first conductive layer in the second trench; and forming a second conductive layer over the second surface of the semiconductor substrate and the first conductive layer.
A detailed description is given in the following embodiments with reference to the accompanying drawings.
The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:
The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims.
Referring to
In
In
In
In
Next, a patterning process (not shown) is performed by using a suitable patterned mask layer (not shown), thereby forming a trench 242 in the surface B′ of the thinned semiconductor substrate 200′, and the trench 242 exposes the bottom surface and portions of the sidewalls of the conductive layer 230. Next, a deposition process (not shown) is performed to form a conductive layer 244 in the trench 242. In one embodiment, the conductive layer 244 may comprise conductive materials such as Ti—TiN alloy, tungsten, AlCu alloy, AlSiCu alloy, and may be formed by a deposition process such as physical vapor deposition (PVD) or chemical vapor deposition (CVD). The formed conductive layer 244 may be processed by a planarization process (not shown), such that a surface of the conductive layer 244 is coplanar with the surface B′ of the thinned semiconductor substrate 200. Next, another deposition process (not shown) is performed to form a blanket conductive layer 246 over the surface of the conductive layer 244 and the surface of the thinned semiconductor substrate 200′. In one embodiment, the conductive layer 246 may comprise conductive materials such as Ti—Ni—Ag alloy, and may be formed by a method such as physical vapor deposition (PVD) or chemical vapor deposition (CVD). Therefore, after removal of the handling substrate (not shown), an exemplar LDMOS device is substantially fabricated, as shown in
In one embodiment, the gate structure G and the doped regions 220 and 222 of the LDMOS device shown in
In addition, in another embodiment, the regions with the first conductivity type of the LDMOS device shown in
While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.
Claims
1. A lateral double diffused metal-oxide-semiconductor (LDMOS) device, comprising:
- a semiconductor substrate, having opposing first and second surfaces and a first conductivity type;
- a well region formed in a portion of the semiconductor substrate adjacent to the first surface thereof, having the first conductivity type;
- a gate structure disposed over a portion of the first surface of the semiconductor substrate;
- a first doped region disposed in a portion of the well region adjacent to a first side of the gate structure, having the first conductivity type;
- a second doped region disposed in a portion of the well region adjacent to a second side of the gate structure opposite to the first side, having a second conductivity type opposite to the first conductivity type;
- a third doped region disposed in a portion of the first doped region, having the second conductivity type;
- a fourth doped region disposed in a portion of the second doped region, having the second conductivity type;
- a first trench formed in a portion of the third doped region, the first doped region, the well region, and the semiconductor substrate;
- a conductive contact formed in the first trench;
- a second trench formed in a portion of the semiconductor substrate adjacent to the second surface thereof, wherein the second trench does not penetrate the semiconductor substrate and exposes a portion of the conductive contact;
- a first conductive layer formed in second trench, contacting the conductive contact; and
- a second conductive layer formed over the second surface of the semiconductor substrate and the first conductive layer.
2. The LDMOS device as claimed in claim 1, wherein the first conductivity type is P type and the second conductivity type is N type, or the first conductivity type is N type and the second conductivity type is P type.
3. The LDMOS device as claimed in claim 1, wherein the third doped region is a source region and the fourth doped region is a drain region.
4. The LDMOS device as claimed in claim 1, wherein the well region has a resistivity lower than a resistivity of the semiconductor substrate.
5. The LDMOS device as claimed in claim 1, wherein the conductive contact comprises a third conductive layer, and a fourth conductive layer surrounded by the third conductive layer.
6. A method for fabricating a lateral double diffused metal oxide semiconductor (LDMOS) device, comprising:
- performing a semiconductor substrate, having opposite first and second surfaces and a first conductivity type;
- performing an ion implantation process, forming a well region in a portion of the semiconductor substrate adjacent to the first surface thereof, having the first conductivity type;
- forming a gate structure over a portion of the well region;
- forming a first doped region in a portion of the well region adjacent to a first side of the gate structure, having the first conductivity type;
- forming a second doped region in a portion of the well region at a second side of the gate structure opposite to the first side, having a second conductivity type opposite to the first conductivity type;
- forming a third doped region in a portion of the first doped region, having the second conductivity type;
- forming a fourth doped region in a portion of the second doped region, having the second conductivity type;
- forming a first trench in a portion of the third doping region, the first doped region, the well region, and the semiconductor substrate;
- forming a conductive contact in the first trench;
- thinning the semiconductor substrate from the second surface thereof;
- after thinning the semiconductor substrate, forming a second trench in a portion of the semiconductor substrate adjacent to the second surface thereof, exposing a portion of the conductive contact, wherein the second trench does not penetrate the semiconductor substrate;
- forming a first conductive layer in the second trench; and
- forming a second conductive layer over the second surface of the semiconductor substrate and the first conductive layer.
7. The method as claimed in claim 6, wherein the first conductivity type is P type and the second conductivity type is N type, or the first conductivity type is N type and the second conductivity type is P type.
8. The method as claimed in claim 6, wherein the third doped region is a source region and the fourth doped region is a drain region.
9. The method as claimed in claim 6, wherein the well region has a resistivity lower than a resistivity of the semiconductor substrate.
10. The method as claimed in claim 6, wherein the conductive contact comprises a third conductive layer and a fourth conductive layer surrounded by the third conductive layer.
Type: Application
Filed: Oct 11, 2013
Publication Date: Apr 16, 2015
Applicant: Vanguard International Semiconductor Corporation (Hsinchu)
Inventors: Tsung-Hsiung LEE (Taoyuan City), Jui-Chun CHANG (Hsinchu City)
Application Number: 14/052,075
International Classification: H01L 29/78 (20060101); H01L 29/66 (20060101);