FORMATION OF LATERAL TRENCH FETS (FIELD EFFECT TRANSISTORS) USING STEPS OF LDMOS (LATERAL DOUBLE-DIFFUSED METAL OXIDE SEMICONDUCTOR) TECHNOLOGY
A semiconductor structure and a method forming the same. The method includes providing a semiconductor structure which includes a semiconductor substrate. The semiconductor substrate includes a top substrate surface which defines a reference direction perpendicular to the top substrate surface. The method further includes simultaneously forming a first doped transistor region of a first transistor and a first doped Source/Drain portion of a second transistor on the semiconductor substrate. The first doped transistor region is not a portion of a Source/Drain region of the first transistor. The first doped transistor region and the first doped Source/Drain portion comprise dopants of a first doping polarity. The method further includes forming a second gate dielectric layer and a second gate electrode region of the second transistor on the semiconductor substrate. The second gate dielectric layer is sandwiched between and electrically insulates the second gate electrode region and the semiconductor substrate.
The present invention relates generally to lateral trench FETs (Field Effect Transistors) and more particularly to formation of the lateral trench FETs using step of LDMOS (Lateral double-Diffused Metal Oxide Semiconductor) technology.
BACKGROUND OF THE INVENTIONIn semiconductor technology, there is a need for LDMOS (Lateral double-Diffused Metal Oxide Semiconductor) and high voltage power devices on the same wafer. Therefore, there is a need for a method for forming the LDMOS and the high voltage power devices on the same wafer that requires fewer steps than in the prior art.
SUMMARY OF THE INVENTIONThe present invention provides a semiconductor structure, comprising (a) a semiconductor substrate which includes a top substrate surface which defines a reference direction perpendicular to the top substrate surface; (b) a first transistor on the semiconductor substrate; and (c) a second transistor on the semiconductor substrate, wherein a first doping profile of a first doped transistor region of the first transistor in the reference direction and a second doping profile of a first doped Source/Drain portion of the second transistor in the reference direction are essentially the same, wherein the first doped transistor region is not a portion of a Source/Drain region of the first transistor, wherein a first gate electrode region of the first transistor is on a first side of the top substrate surface, wherein a second gate electrode region of the second transistor is on a second side of the top substrate surface, and wherein the first side and the second side are opposite sides of the top substrate surface.
The present invention provides a method for forming the LDMOS and the high voltage power devices on the same wafer that requires fewer steps than in the prior art.
Next, with reference to
Next, with reference to
As a result of the N− region 120 and the N− regions 120a and 120b being formed by the same ion implantation process, a depth 121 of the N− region 120 and a depth 121′ of the N− regions 120a and 120b are equal. The depth 121 of the N− region 120 is the vertical distance from the top surface 115 of the substrate 110 to the bottom surface 125 of the N− region 120. The depth 121′ of the N− regions 120a and 120b is a vertical distance from the top surface 115 of the substrate 110 to the bottom surface 125′ of the N− region 120b. Similarly, a depth 112′ of the deep trench isolation region 112+114 is a vertical distance from the top surface 115 of the substrate 110 to the bottom surface 112b of the dielectric layer 112 (the depth 112′ is also considered the depth 112′ of the dielectric layer 112). In one embodiment, the depth 112′ is greater than the depth 121. In one embodiment, for illustration, the depth 112′ is also considered the depth of the poly-silicon region 114.
Also as a result of the N− region 120 and the N− regions 120a and 120b being formed by the same ion implantation process, doping concentrations with respect to the depth (i.e., in the reference direction 127 which is perpendicular to the top surface 115 of the substrate 110) in the N− region 120 and the N− regions 120a and 120b have the same doping profile. The doping profile of the N− region 120 is the dopant concentration of the N− region 120 distributed along the depth 121 of the N− region 120. The doping profiles of the N− regions 120a and 120b are the dopant concentrations of the N− regions 120a and 120b distributed along the depth 121′ of the N− regions 120a and 120b.
Next, with reference to
Next, with reference to
Next, with reference to
Next, an N− region 132 is formed in the P-body region 130. The N− region 132 comprises n-type dopants. The N− region 132 can be formed by a selective ion implantation process. In one embodiment, the ion implantation process that forms the N− regions 132 also implants n-type dopants into the N+ regions 116a and 116b resulting in N+ regions 132a and 132b. As a result, the N+ regions 132a and 132b comprise n-type dopants from two separate ion implantation processes that form the N− region 132 and the N+ regions 116a and 116b.
Next, with reference to
Next, in one embodiment, an extension region 131 is formed in the P-body region 130. The extension region 131 comprises n-type dopants. The extension region 131 can be formed by a conventional method.
Next, with reference to
Next, in one embodiment, a P+ region 134, N+ regions 136, 136′, 136a, and 136b are formed in the semiconductor structure 100. The P+ region 134 comprises p-type dopants. The N+ regions 136, 136′, 136a, and 136b comprise n-type dopants. The P+ region 134 and the N+ regions 136, 136′, 136a, and 136b can be formed by a conventional method. More specifically, in one embodiment, the N+ regions 136, 136′, 136a, and 136b can be formed by an ion implantation process.
Next, in one embodiment, silicide regions 170 are formed on the P+ region 134 and the N+ regions 136, 136′, 136a, and 136b. The silicide regions 170 can be formed by a conventional method.
Next, in one embodiment, a dielectric layer (not shown) is formed on top of the structure 100 of
It should be noted that a structure 180 of the semiconductor structure 100 of
It should be noted that regions of the lateral trench FET 190 (except the gate dielectric layer 112 and the gate electrode region 114) are formed using steps in the fabrication process of the LDMOS transistor 180. The lateral trench FET 190 can serve as a high voltage power device that has a breakdown voltage in the range from 120V to 150V.
Next, with reference to
Next, with reference to
Next, in one embodiment, the gate dielectric region 140, the gate electrode region 150, and the extension region 131 are formed on the P-body region 130. The gate dielectric region 140, the gate electrode region 150, and the extension region 131 can be formed in a manner similar to the manner in which the gate dielectric region 140, the gate electrode region 150, and the extension region 131 of
Next, with reference to
Next, in one embodiment, silicide regions 170 are formed on the P+ region 134, the N+ regions 136, 136′, 136a, and 136b, and the silicon germanium region 280. The silicide regions 170 can be formed by a conventional method.
It should be noted that a structure 290 of the semiconductor structure 200 of
Next, with reference to
It should be noted that a structure 390 of the semiconductor structure 300 of
In one embodiment, the LDMOS transistor 480 is formed by a conventional method. In one embodiment, the first and second Source/Drain regions 420a+416a+424a+428a and 420b+416b+424b+428b of the lateral trench FET 490 are formed using steps in the fabrication process of the LDMOS transistor 480. The formation of a deep trench isolation region 412+414 is similar to the formation of the deep trench isolation region 112+114 of
With reference to
In summary, the first and second Source/Drain regions of the lateral trench FETs 190, 290, and 390 of
While particular embodiments of the present invention have been described herein for purposes of illustration, many modifications and changes will become apparent to those skilled in the art. Accordingly, the appended claims are intended to encompass all such modifications and changes as fall within the true spirit and scope of this invention.
Claims
1. A semiconductor structure, comprising:
- (a) a semiconductor substrate which includes a top substrate surface which defines a reference direction perpendicular to the top substrate surface;
- (b) a first transistor on the semiconductor substrate; and
- (c) a second transistor on the semiconductor substrate, wherein a first doping profile of a first doped transistor region of the first transistor in the reference direction and a second doping profile of a first doped Source/Drain portion of the second transistor in the reference direction are essentially the same, wherein the first doped transistor region is not a portion of a Source/Drain region of the first transistor, wherein a first gate electrode region of the first transistor is on a first side of the top substrate surface, wherein a second gate electrode region of the second transistor is on a second side of the top substrate surface, and wherein the first side and the second side are opposite sides of the top substrate surface.
2. The structure of claim 1,
- wherein the first doped transistor region of the first transistor has a first depth in the reference direction,
- wherein the first doped Source/Drain portion of the second transistor has a second depth in the reference direction, and
- wherein the first depth is essentially equal to the second depth.
3. The structure of claim 1,
- wherein the first doped Source/Drain portion of the second transistor has a second depth in the reference direction,
- wherein the second gate electrode region of the second transistor has a third depth in the reference direction, and
- wherein the third depth is greater than the second depth.
4. The structure of claim 1,
- wherein the first doped Source/Drain portion of the second transistor has a second depth in the reference direction,
- wherein the second gate electrode region of the second transistor has a fourth depth in the reference direction, and
- wherein the fourth depth is less than the second depth.
5. A semiconductor structure fabrication method, comprising:
- providing a semiconductor structure which includes a semiconductor substrate, wherein the semiconductor substrate includes a top substrate surface which defines a reference direction perpendicular to the top substrate surface;
- simultaneously forming a first doped transistor region of a first transistor and a first doped Source/Drain portion of a second transistor on the semiconductor substrate, wherein the first doped transistor region is not a portion of a Source/Drain region of the first transistor, wherein the first doped transistor region and the first doped Source/Drain portion comprise dopants of a first doping polarity; and
- forming a second gate dielectric layer and a second gate electrode region of the second transistor on the semiconductor substrate, wherein the second gate dielectric layer (i) is sandwiched between and (ii) electrically insulates the second gate electrode region and the semiconductor substrate.
6. The method of claim 5, further comprising forming a first gate dielectric layer and a first gate electrode region of the second transistor on the semiconductor substrate,
- wherein the first gate dielectric layer (i) is sandwiched between and (ii) electrically insulates the first gate electrode region and the semiconductor substrate,
- wherein a first gate electrode region of the first transistor is on a first side of the top substrate surface,
- wherein a second gate electrode region of the second transistor is on a second side of the top substrate surface, and
- wherein the first side and the second side are opposite sides of the top substrate surface.
7. The method of claim 5, wherein said simultaneously forming the first doped transistor region and the first doped Source/Drain portion comprises implanting dopants in the semiconductor substrate by ion implantation.
8. The method of claim 5,
- wherein the first doped transistor region of the first transistor has a first depth in the reference direction,
- wherein the first doped Source/Drain portion of the second transistor has a second depth in the reference direction, and
- wherein the first depth is essentially equal to the second depth.
9. The method of claim 5, further comprising simultaneously forming a second doped transistor region of the first transistor and a second doped Source/Drain portion of the second transistor on the semiconductor substrate,
- wherein the second doped transistor region and the second doped Source/Drain portion comprise dopants of the first doping polarity, and
- wherein the second doped Source/Drain portion is in direct physical contact with the first doped Source/Drain portion.
10. The method of claim 9, wherein said simultaneously forming the second doped transistor region and the second doped Source/Drain portion comprises implanting dopants in the semiconductor substrate by ion implantation.
11. The method of claim 9, further comprising forming a third doped transistor region of the first transistor on the semiconductor substrate,
- wherein the third doped transistor region comprises dopants of a second doping polarity which is opposite to the first doping polarity.
12. The method of claim 11, further comprising simultaneously forming a fourth doped transistor region of the first transistor and a fourth doped Source/Drain portion of the second transistor on the semiconductor substrate,
- wherein the fourth doped transistor region and the fourth doped Source/Drain portion comprise dopants of the first doping polarity, and
- wherein the fourth doped Source/Drain portion is in direct physical contact with the second doped Source/Drain portion.
13. The method of claim 12, wherein said simultaneously forming the fourth doped transistor region and the fourth doped Source/Drain portion comprises implanting dopants in the semiconductor substrate by ion implantation.
14. The method of claim 12, further comprising simultaneously forming a fifth doped transistor region of the first transistor and a fifth doped Source/Drain portion of the second transistor on the semiconductor substrate,
- wherein the fifth doped transistor region and the fifth doped Source/Drain portion comprise dopants of the first doping polarity, and
- wherein the fifth doped Source/Drain portion is in direct physical contact with the fourth doped Source/Drain portion.
15. The method of claim 5, wherein said forming the second gate dielectric layer and the second gate electrode region is performed before said simultaneously forming the first doped transistor region and the first doped Source/Drain portion is performed.
16. The method of claim 15,
- wherein the first doped Source/Drain portion of the second transistor has a second depth in the reference direction,
- wherein the second gate dielectric layer of the second transistor has a third depth in the reference direction, and
- wherein the third depth is greater than the second depth.
17. The method of claim 15, further comprising, after said forming the second gate dielectric layer and the second gate electrode region is performed, forming a shallow trench isolation (STI) region on the semiconductor substrate,
- wherein the STI region is in direct physical contact with the second gate dielectric layer and the second gate electrode region.
18. The method of claim 5, wherein said forming the second gate dielectric layer and the second gate electrode region is performed after said simultaneously forming the first doped transistor region and the first doped Source/Drain portion is performed.
19. The method of claim 18,
- wherein the first doped Source/Drain portion of the second transistor has a second depth in the reference direction,
- wherein the second gate dielectric layer of the second transistor has a fourth depth in the reference direction, and
- wherein the fourth depth is less than the second depth.
20. The method of claim 18, further comprising, before said forming the second gate dielectric layer and the second gate electrode region is performed, forming a shallow trench isolation (STI) region on the semiconductor substrate,
- wherein the STI region is in direct physical contact with the second gate dielectric layer.
Type: Application
Filed: Jul 16, 2007
Publication Date: Jan 22, 2009
Inventor: Steven Howard Voldman (South Burlington, VT)
Application Number: 11/778,428
International Classification: H01L 29/94 (20060101); H01L 21/8236 (20060101);