Semiconductor device and manufacturing method of the same

• US 20050179085A1
• Filed: 07/29/2004
• Published: 08/18/2005
• Est. Priority Date: 02/13/2004
• Status: Active Grant

• Current Assignee: Fujitsu Semiconductor Limited (Fujitsu Limited)
• Original Assignee: Fujitsu Limited
• Inventors: Nakamura, Shunji, Yamauchi, Tsunenori
• Granted Patent: US 7,348,630 B2
• Time in Patent Office: Days
• US Class Current: 257/344
• CPC Class Codes: H01L 29/1045 the doping structure being parallel to the channel length, e.g. DMOS like
• CPC Class Codes: H01L 29/1083 with an inactive supplementary region, e.g. for preventing punch-through, improving capacity effect or leakage current
• CPC Class Codes: H01L 29/402 Field plates
• CPC Class Codes: H01L 29/456 on silicon
• CPC Class Codes: H01L 29/495 the conductor material next to the insulator being a simple metal, e.g. W, Mo H01L29/4908, H01L29/4983 take precedence
• CPC Class Codes: H01L 29/66545 using a dummy, i.e. replacement gate in a process wherein at least a part of the final gate is self aligned to the dummy gate
• CPC Class Codes: H01L 29/66659 with asymmetry in the channel direction, e.g. lateral high-voltage MISFETs with drain offset region, extended drain MISFETs
• CPC Class Codes: H01L 29/7835 with asymmetrical source and drain regions, e.g. lateral high-voltage MISFETs with drain offset region, extended drain MISFETs

Abstract

Substitution reaction between polysilicon and Al (aluminum) is utilized. Namely, polysilicon films are formed by patterning at first as in the related art, and after an Al film is formed on an interlayer insulating film to be in contact with the polysilicon films, the polysilicon films in the interlayer insulating film 9 are replaced with Al by heat treatment. By patterning, gate electrodes constituted of Al low in gate parasite resistance and high in mobility is formed.

Claims

1. A semiconductor device, comprising:

a semiconductor substrate;

gate electrodes formed above said semiconductor substrate;

a pair of impurity diffusion layers formed in a surface layer of said semiconductor substrate at both sides of each of said gate electrodes; and

drift layers formed in the surface layer of said semiconductor substrate between said gate electrodes and one of said impurity diffusion layers as a same conduction type as said impurity diffusion layers,

wherein said gate electrodes are each formed in an overhang shape with metal including aluminum as a material.

2. The semiconductor device according to claim 1, wherein an upper part of each of said gate electrodes is formed in an asymmetrical shape extending longer to a side of the one of said impurity diffusion layers on the other side.

3. The semiconductor device according to claim 1, further comprising:

a pair of electrodes formed above said semiconductor substrate to be connected to said respective impurity diffusion layers,

wherein each of said electrodes is formed of the same material as said gate electrodes.

4. The semiconductor device according to claim 3,

wherein said gate electrodes and said each electrode are formed so that lower parts of said electrodes are embedded in an interlayer insulating film formed above said semiconductor substrate, and

wherein said each electrode is formed with a metallic underlying film interposed between said each electrode and said interlayer insulating film, and said gate electrodes are formed to be in direct contact with the interlayer insulating film.

5. The semiconductor device according to claim 3, wherein shield layers formed of the same material as said gate electrodes to partition both the gate electrodes and one of said electrodes are included between said gate electrodes and one of said electrodes.

6. A manufacturing method of a semiconductor device, comprising the steps of:

forming polysilicon films each in an electrode shape via a gate insulating film on a semiconductor substrate;

introducing an impurity into a surface layer of the semiconductor substrate and forming a pair of impurity diffusion layers, and drift layers, respectively;

forming an interlayer insulating film above the semiconductor substrate to cover the polysilicon films;

exposing top surfaces of the polysilicon films by removing a surface layer of the interlayer insulating film;

forming openings in the interlayer insulating film to expose a part of a surface of each of the impurity diffusion layers;

forming a metallic film including aluminum on the interlayer insulating film to fill each of the openings;

selectively performing substitution reaction of polysilicon and aluminum and charging regions of formation of the polysilicon films in the interlayer insulating film with the material of the metallic film; and

forming a pair of electrodes connected to the respective impurity diffusion layers and gate electrodes integrally formed of the material of the metallic film by working the metallic film.

7. The manufacturing method of the semiconductor device according to claim 6, further comprising the steps of:

forming an underlying film on the interlayer insulating film to cover an internal wall surface of each of the openings after forming the each of the openings before forming each of the metallic film; and

removing only regions of the underlying film corresponding to portions on the polysilicon films, and exposing top surfaces of the polysilicon films.

8. The manufacturing method of the semiconductor device according to claim 6, wherein on working the metallic film, at least the gate electrodes are formed into an overhang shape.

9. The manufacturing method of the semiconductor device according to claim 8, wherein on working the metallic film, an upper part of the gate electrode is formed into an asymmetrical shape extended longer to a side of the one of the impurity diffusion layers on the other side.

10. The manufacturing method of the semiconductor device according to claim 6, wherein on working the metallic film, between each of regions to be the gate electrodes and a region to be one of the electrodes, a shield layer for partitioning both of them is formed with the gate electrodes and the each electrode.

11. The manufacturing method of the semiconductor device according to claim 10,

wherein on forming the polysilicon film, other polysilicon films adjacent to the polysilicon films above the semiconductor substrate are formed with the polysilicon films,

wherein on the substitution reaction, regions of formation of the other polysilicon films as well as the region of formation of the polisilicon films in the interlayer insulating film are replaced with the metallic film respectively, and

wherein on working the metallic film, the shield layer integrally formed of the material of the metallic film are formed of the pair of electrodes and the gate electrode.