METHOD FOR MANUFACTURING MULTI-GATE TRANSISTOR DEVICE
A method for manufacturing multi-gate transistor device includes providing a semiconductor substrate having a patterned semiconductor layer and a patterned hard mask sequentially formed thereon, removing the patterned hard mask, performing a thermal treatment to rounding the patterned semiconductor layer with a process temperature lower than 800° C., and sequentially forming a gate dielectric layer and a gate layer covering a portion of the patterned semiconductor layer on the semiconductor substrate.
1. Field of the Invention
The invention relates to a method for manufacturing a multi-gate transistor device.
2. Description of the Prior Art
Conventional planar metal-oxide-semiconductor (MOS) transistor has difficulty when scaling down to 65 nm and below. Therefore the non-planar transistor technology such as Fin Field effect transistor (FinFET) technology that allows smaller size and higher performance is developed to replace the planar MOS transistor.
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However, the FinFET device 100 still faces many problems. For example, the electrical performance of the FinFET device 100 is seriously impacted by the surface roughness of the source/drain 108 while the FinFET device 100 always suffers corner leakage at the fin. Therefore, it is still in need to develop a method for manufacturing multi-gate transistor device that is able to solve the above mentioned problems.
SUMMARY OF THE INVENTIONAccording to an aspect of the present invention, a method for manufacturing multi-gate transistor device is provided. The method includes providing a semiconductor substrate having a patterned semiconductor layer and a patterned hard mask sequentially formed thereon, removing the patterned hard mask, performing a thermal treatment to rounding the patterned semiconductor layer with a process temperature lower than 800° C., and sequentially forming a gate dielectric layer and a gate layer covering a portion of the patterned semiconductor layer on the semiconductor substrate.
According to the method for manufacturing a multi-gate transistor device provided by the present invention, the corners of the patterned semiconductor layer are rounded by performing the thermal treatment with the process temperature lower than 800° C., that fulfills the low thermal budget requirement of FinFET process. Consequently, corner leakage is prevented. In the same time, surface roughness of the patterned semiconductor layer is improved by the thermal treatment, and thus the formation result of the gate dielectric layer and the gate layer, which are formed on the patterned semiconductor layer, is improved. Consequently the method for manufacturing multi-gate transistor device improves electric performance of the obtained multi-gate transistor device.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
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After forming the gate dielectric layer 220 and the gate layer 222, a tilted implantation as required is performed to form a source/drain extension regions (not shown) in the patterned semiconductor layer 206. Subsequently, a spacer (not shown) is formed on sidewalls of the gate layer 222 and the gate dielectric layer 220. Additionally, the spacer can be a single-layered or multi-layered structure. After forming the spacer, a selective epitaxial growth (SEG) process is performed to form an epitaxial layer (not shown) on the patterned semiconductor layer 206. Furthermore, materials having lattice constant different from the patterned semiconductor layer 206 is introduced in the SEG process according to the requirement to conductivity types of the multi-gate transistor device. And dopants of a conductivity type can also be introduced before, after or simultaneously in the SEG process. Consequently, source/drain for a multi-gate transistor device and a multi-gate transistor device are simultaneously obtained. Since the elements such as the gate dielectric layer 220, the gate layer 222, the source/drain extension regions, the spacer and the epitaxial source/drain are well known to those skilled in the art, those details are omitted in the interest of brevity.
According to the method for manufacturing a multi-gate transistor device of the first preferred embodiment, the thermal treatment 210 is provided to rounding the sharp corners of the patterned semiconductor layer 206. By introducing hydrogen, smooth arc corners (as shown in Circle 206b) are easily obtained by the thermal treatment 210 under 740° C., which fulfills the lower thermal budget requirement to FinFET process. Consequently, corner leakage is prevented. Furthermore, the thermal treatment 210 provided by the preferred embodiment improves the surface roughness of the patterned semiconductor layer 206 and therefore improves the formation result of the gate dielectric layer 220 and the gate layer 222. Thus electric performance of the multi-gate transistor device is improved. In addition, because the thermal treatment 210 is able to rounding the corner of the patterned semiconductor layer 206 adjacent to the semiconductor substrate 200, a recess (as shown in Circle 206c) is formed and selectively followed by forming a pad oxide layer in the recess. The above mentioned approach is introduced to reduce the point leakage current.
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As mentioned above, a patterned hard mask for defining at least a fin of a multi-gate transistor device is then formed on the semiconductor substrate 200 and followed by performing an etching process. Thus a portion of the semiconductor material of the semiconductor substrate 200 is removed to form at least a patterned semiconductor layer 206 on the semiconductor substrate 200. The patterned semiconductor layer 206 includes a width and a height, and a ratio between the width and the height is about 1:1.5-1:2, but not limited to this. After forming the patterned semiconductor layer 206, the patterned hard mask is removed to expose the patterned semiconductor layer 206. As mentioned above, the patterned semiconductor layer 206 is a slim structure having rectangular cross-section view. Therefore, the corners of the patterned semiconductor layer 206, which are emphasized by Circle 206a in
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Subsequently, elements such as the gate dielectric layer 220, the gate layer 222, the source/drain extension regions, the spacer, and the epitaxial source/drain are sequentially formed as mentioned above, and those details are therefore omitted for simplicity.
According to the method for manufacturing a multi-gate transistor device of the second preferred embodiment, the thermal treatment 230 is provided to rounding the sharp corners of the patterned semiconductor layer 206. By introducing hydrogen and HCl, smooth arc corners (as shown in Circle 206b) are easily obtained by the thermal treatment 230 under 720° C., which fulfills the lower thermal budget requirement to FinFET process. Consequently, corner leakage is prevented. Furthermore, the thermal treatment 230 provided by the preferred embodiment improves the surface roughness of the patterned semiconductor layer 206 and therefore improves the formation result of the gate dielectric layer 220 and the gate layer 222. Thus electric performance of the multi-gate transistor device is improved. In addition, because the thermal treatment 230 is able to rounding the corners of the patterned semiconductor layer 206 adjacent to the semiconductor substrate 200, a recess (as shown in Circle 206c) is formed and selectively followed by forming a pad oxide layer in the recess. The above mentioned approach is introduced to reduce the point leakage current.
According to the method for manufacturing a multi-gate transistor device provided by the present invention, the corners of the patterned semiconductor layer are rounded by performing the thermal treatment with the process temperature lower than 800° C., even lower than 720° C., that fulfills the low thermal budget requirement of FinFET process. Consequently, corner leakage is prevented. In the same time, surface roughness of the patterned semiconductor layer is improved by the thermal treatment, and thus the formation result of the gate dielectric layer and the gate layer, which are formed on the patterned semiconductor layer, is improved. The thermal treatment even changes the lattice orientation of the patterned semiconductor layer. Accordingly the method for manufacturing multi-gate transistor device improves electric performance of the obtained multi-gate transistor device.
Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.
Claims
1. A method for manufacturing multi-gate transistor device, comprising:
- providing a semiconductor substrate having a patterned semiconductor layer and a patterned hard mask sequentially formed thereon;
- removing the patterned hard mask;
- performing a thermal treatment to rounding the patterned semiconductor layer with a process temperature of the thermal treatment is lower than 800° C.; and
- sequentially forming a gate dielectric layer and a gate layer covering a portion of the patterned semiconductor layer on the semiconductor substrate.
2. The method for manufacturing multi-gate transistor device according to claim 1, wherein the semiconductor substrate comprises a silicon-on-insulator (SOI) substrate or a bulk silicon substrate.
3. The method for manufacturing multi-gate transistor device according to claim 1, wherein the gate dielectric layer comprises a high dielectric constant (high-k) material.
4. The method for manufacturing multi-gate transistor device according to claim 1, wherein the thermal treatment comprises a step of introducing nitrogen.
5. The method for manufacturing multi-gate transistor device according to claim 4, wherein the thermal treatment comprises a process pressure and the process pressure is lower than 1 Torr.
6. The method for manufacturing multi-gate transistor device according to claim 4, wherein the process temperature of the thermal treatment is preferably lower than 740° C.
7. The method for manufacturing multi-gate transistor device according to claim 1, wherein the thermal treatment comprises a step of introducing nitrogen and hydrogen chloride (HCl).
8. The method for manufacturing multi-gate transistor device according to claim 7, wherein the thermal treatment comprises a process pressure and the process pressure is lower than 10 Torr.
9. The method for manufacturing multi-gate transistor device according to claim 7, wherein the process temperature of the thermal treatment is lower than 720° C.
10. The method for manufacturing multi-gate transistor device according to claim 7, wherein a gas flow rate of nitrogen is between 20 standard liter per minute (slm) and 40 slm.
11. The method for manufacturing multi-gate transistor device according to claim 7, wherein a gas flow rate of HCl is between 20 standard cubic centimeter per minute (sccm) and 120 sccm.
12. The method for manufacturing multi-gate transistor device according to claim 1, wherein a process duration of the thermal treatment is less than 2 minutes.
Type: Application
Filed: Nov 16, 2011
Publication Date: May 16, 2013
Inventors: Chin-I Liao (Tainan City), Chia-Lin Hsu (Tainan City), Ming-Yen Li (Taichung City), Min-Ying Hsu (Tainan City), Hsin-Huei Wu (Chiayi City), Yung-Lun Hsieh (Tainan City), Chien-Hao Chen (Yun-Lin County), Bo-Syuan Lee (Tainan City)
Application Number: 13/298,264
International Classification: H01L 21/28 (20060101);