Semiconductor device manufacturing method and semiconductor device
A manufacturing method of a semiconductor device having a highly reliable capacitor, and the semiconductor device are provided. The semiconductor device manufacturing method according to the present invention includes: a first step of forming a first electrode of a capacitor on a semiconductor substrate; a second step of forming a capacitor insulating film on the whole surface including a side surface and an upper surface of the first electrode; a third step of forming a protection insulating film made of a material different from that of the capacitor insulating film, on the capacitor insulating film; a fourth step of removing the protection insulating film and the capacitor insulating film from the upper surface of the first electrode, by anisotropically etching the protection insulating film and the capacitor insulating film; a fifth step of removing the protection insulating film that remains on the side surface of the first electrode; and a sixth step of forming a second electrode of the capacitor on the capacitor insulating film, after removing the protection insulating film.
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The present invention relates to a semiconductor device manufacturing method and a semiconductor device. Particularly, the invention relates to a semiconductor device having a stacked capacitor, and a method of manufacturing the semiconductor device.
BACKGROUND OF THE INVENTIONConventionally, in a DRAM (Dynamic Random Access Memory) having a stacked capacitor, in order to compensate for a decrease of electrostatic capacitance due to a reduction in the size of the capacitor, the height of the capacitor has been increased or a high dielectric material has been used for a capacitor insulating film.
However, when the size of the capacitor further decreases in future, the above measure is not sufficient, and the configuration of the capacitor needs to be more complex. When the capacitor has a more complex configuration, a process of processing the capacitor insulating film becomes additionally necessary. For example, when a capacitor configuration in which plural capacitor layers are laminated is considered, in order to secure a connection between an upper electrode of a lower layer and an upper electrode of an upper layer and between a lower electrode of the lower layer and a lower electrode of the upper layer, respectively, it becomes necessary to perform etch back or the like on the capacitor insulating film, thereby exposing a connection part between the upper and the lower electrodes. When the capacitor insulating film is to be etched, the following problems occur.
First, as shown in
However, due to this etch back process, an adhesion X of an etching damage, a residual molecule of an etching product, or the like occurs on the surface of the capacitor insulating film 202. This etching damage, the residual molecule, or the like increases a leakage of current between an upper electrode 203 and the lower electrode 201 as shown by an arrowhead A in
At a lower end of the capacitor insulating film 202, there is an interface with the interlayer insulating film 200, and a connection of atom level is disconnected. Further, due to the etch back, the capacitor insulating film becomes locally thin. Consequently, leakage current occurs easily at the lower end of the capacitor insulating film 202, as shown by an arrowhead B in
Semiconductor devices having the stacked capacitors are described in, for example, Japanese Patent Application Laid-open Nos. 2000-332213, H05-267614, H11-345948, 2004-111711, and 2001-24169.
SUMMARY OF THE INVENTIONThe present invention has been achieved to solve the above problems. It is an object of the present invention to provide a manufacturing method of a semiconductor device having a highly reliable capacitor, which suppresses an etching damage on a capacitor insulating film of the capacitor and suppress occurrence of leakage current, and the semiconductor device.
It is another object of the invention to provide a semiconductor device that can suppress the occurrence of leakage current at the lower end of a capacitor insulating film of a capacitor, and a method of manufacturing this semiconductor device.
The semiconductor device manufacturing method according to the present invention includes: a first step of forming a first electrode of a capacitor on a semiconductor substrate; a second step of forming a capacitor insulating film on the whole surface including a side surface and an upper surface of the first electrode; a third step of forming a protection insulating film made of a material different from that of the capacitor insulating film, on the capacitor insulating film; a fourth step of removing the protection insulating film and the capacitor insulating film from the upper surface of the first electrode, by anisotropically etching the protection insulating film and the capacitor insulating film; a fifth step of removing the protection insulating film that remains on the side surface of the first electrode; and a sixth step of forming a second electrode of the capacitor on the capacitor insulating film, after removing the protection insulating film.
According to the semiconductor device manufacturing method of the present invention, the surface of the capacitor insulating film is protected by the protection insulating film, at the time of performing anisotropic etching of the capacitor insulating film. Therefore, an etching damage or a residual molecule of an etching product occurs on only the surface of the protection insulating film. Since the protection insulating film is removed after the etching, a damaged layer and a residual molecule of the protection insulating film can be completely removed. Therefore, the surface of the capacitor insulating film can be kept clean. Consequently, increase in the leakage current of the capacitor and reduction in reliability can be prevented.
Further, after performing the anisotropic etching, a part of the capacitor insulating film that extends in a direction of a second electrode is formed in a width corresponding to the film thickness of the protection insulating film, at a lower end of the capacitor insulating film. Accordingly, the occurrence of leakage current between a first electrode and a second electrode at the lower end of the capacitor insulating film can be suppressed.
The semiconductor device includes a capacitor according to the present invention comprising: a first electrode provided on a semiconductor substrate; a capacitor insulating film provided on a side surface of the first electrode; and a second electrode provided on a surface of the capacitor insulating film facing the first electrode, wherein the capacitor insulating film has a first part along the side surface of the first electrode, and a second part extending substantially in parallel with the semiconductor substrate from a lower end of the first part in a direction of the second electrode.
According to the semiconductor device of the present invention, presence of the second part at the lower end of the capacitor insulating film can suppress the occurrence of leakage current between the first electrode and the second electrode at the lower end of the capacitor insulating film.
BRIEF DESCRIPTION OF THE DRAWINGSThe above and other objects, features and advantages of the present invention will become more apparent by reference to the following detailed description of the invention taken in conjunction with the accompanying drawings, wherein:
An exemplary embodiment of a semiconductor device manufacturing method according to the present invention will be explained below with reference to the accompanying drawings. The present invention is adopted in a DRAM in the embodiment.
First, as shown in
Next, an interlayer insulating film 103 is formed on the whole surface, and thereafter, contact plugs 104 that are respectively connected to the diffusion layers 102 are formed. Polysilicon can be used for a material of the contact plugs 104. Next, an interlayer insulating film 105 is formed on the whole surface, and then, contact plugs (not shown) to be respectively connected to bit lines and the contact plugs 104 or the other diffusion layers are formed. Thereafter, a tungsten film is formed on the whole surface, and the tungsten film is patterned to form bit lines 106.
Next, a silicon oxide film 107 and a silicon nitride film 108 are formed on the whole surface, and contact plugs 109 are formed. The contact plugs 109 are formed to be respectively connected to the contact plugs 104. A laminated film of Ti/TiN and tungsten (W) can be used for a material of the contact plugs 109. The configuration as shown in
Next, as shown in
Next, as shown in
Next, as shown in
While an etching damage and an etching product adhere to the surface of the silicon oxide film 116 in the anisotropic etching (etch back) process, the silicon oxide film 116 becomes the etching protection film. Therefore, adhesion of an etching damage or an etching product to the tantalum oxide film (capacitor insulating film) 115 beneath the silicon oxide film 116 can be prevented.
Next, as shown in
Next, as shown in
As shown in
Next, the tungsten film 118 and the silicon oxide film 117 are polished by the CMP method, using the cap insulating film 112 as a stopper. In this process, storage electrodes 119 of the capacitors filled in the through-holes 114 are obtained as shown in
Next, as shown in
Advantageous effects of the embodiment will be explained in detail below.
As shown in
Accordingly, as shown in
In the present embodiment, after the protection insulating film 116 is formed on the capacitor insulating film 115, the protection insulating film 116 and the capacitor insulating film 115 are etched back. With this arrangement, as shown in
In the present embodiment, as shown in
When anisotropic etching (etch back) process is performed after the capacitor insulating film 115 and the protection insulating film 116 are formed as shown in
A pattern formed by lithography is usually narrower than a desired pattern. However, in the present embodiment, the plate electrode is formed before the storage electrodes by lithography. Therefore, even when the pattern of the plate electrode is narrower than the desired pattern, the surface area of the storage electrode formed thereafter is not made smaller, and is rather increased. In other words, even when the pattern shape of the plate electrode varies due to the variation in the lithography condition, this variation works to increase the electrostatic capacity, as compared with a storage electrode of island-shape pattern which is independently formed beforehand as in the conventional process. Therefore, a possibility of a capacity shortage can be reduced.
In the present embodiment, plural capacitor layers having the same shape as that of the capacitor layer 10 can be also laminated, by repeating plural times substantially the same process as shown in
While preferred embodiments of the present invention have been described hereinbefore, the present invention is not limited to the aforementioned embodiments and various modifications can be made without departing from the spirit of the present invention. It goes without saying that such modifications are included in the scope of the present invention.
While, as an example, the plate electrode is formed first and then the storage electrode is formed in the above embodiment, the present invention is not limited to this particular process. Alternatively, the storage electrode can be formed first, and then, the plate electrode can be formed. When the plate electrode is formed first in the present invention, the above effect can be obtained.
While a laminated film of a Ti/TiN film, an AlCu film, and a TiN film is used for the plate electrode in the above embodiment, other conductive materials such as a tungsten film may be used instead. Materials of other insulating films and wirings can be also suitably changed.
An aluminum oxide film or an hafnium oxide film, or a laminated film of these films can be used, instead of the tantalum oxide film, for the material of the capacitor insulating film.
According to the present invention, anisotropic etching is performed after a protection insulating film is formed on a capacitor insulating film. Therefore, the occurrence of an etching damage on the surface of the capacitor insulating film can be prevented.
Further, a part of the capacitor insulating film extending in a lateral direction corresponding to a film thickness of the protection insulating film is formed at a lower end of the capacitor insulating film. Therefore, the occurrence of leakage current of a capacitor at the lower end of the capacitor insulating film can be suppressed.
Claims
1. A semiconductor device manufacturing method, comprising:
- a first step of forming a first electrode of a capacitor on a semiconductor substrate;
- a second step of forming a capacitor insulating film on the whole surface including a side surface and an upper surface of the first electrode;
- a third step of forming a protection insulating film made of a material different from that of the capacitor insulating film, on the capacitor insulating film;
- a fourth step of removing the protection insulating film and the capacitor insulating film from the upper surface of the first electrode, by anisotropically etching the protection insulating film and the capacitor insulating film;
- a fifth step of removing the protection insulating film that remains on the side surface of the first electrode; and
- a sixth step of forming a second electrode of the capacitor on the capacitor insulating film, after removing the protection insulating film.
2. The semiconductor device manufacturing method as claimed in claim 1, wherein
- at the first step, a cap insulating film of the same pattern as that of the first electrode is formed on the first electrode, and
- at the end of the anisotropic etching at the fourth step, the anisotropic etching is controlled so that the capacitor insulating film covers at least a part of the side surface of the cap insulating film.
3. The semiconductor device manufacturing method as claimed in claim 1, wherein
- the first electrode is a plate electrode, and the second electrode is a storage electrode.
4. The semiconductor device manufacturing method as claimed in claim 2, wherein
- the first electrode is a plate electrode, and the second electrode is a storage electrode.
5. The semiconductor device manufacturing method as claimed in claim 3, wherein
- the first step comprises:
- a first sub step of forming a first electrode material on the semiconductor substrate; and
- a second sub step of forming the plate electrode by patterning the first electrode material.
6. The semiconductor device manufacturing method as claimed in claim 4, wherein
- the first step comprises:
- a first sub step of forming a first electrode material on the semiconductor substrate; and
- a second sub step of forming the plate electrode by patterning the first electrode material.
7. The semiconductor device manufacturing method as claimed in claim 5, wherein
- by the patterning at the second sub step, through-holes are formed in the plate electrode,
- at the fourth step, the laminated film of the capacitor insulating film and the protection insulating film is left on the inner side surface of the through-holes, and bottom portions of the through-holes are exposed, and
- at the sixth step, a second electrode material is filled in the through-holes to form the storage electrode.
8. The semiconductor device manufacturing method as claimed in claim 6, wherein
- by the patterning at the second sub step, through-holes are formed in the plate electrode,
- at the fourth step, the laminated film of the capacitor insulating film and the protection insulating film is left on the inner side surface of the through-holes, and bottom portions of the through-holes are exposed, and
- at the sixth step, a second electrode material is filled in the through-holes to form the storage electrode.
9. The semiconductor device manufacturing method as claimed in claim 1, wherein
- the capacitor includes a plurality of laminated capacitor layers, each of the laminated capacitor layers has the first electrode, the capacitor insulating film and the second electrode, and the first electrode and the second electrode of each of the laminated capacitor layers are electrically connected to each other, respectively.
10. The semiconductor device manufacturing method as claimed in claim 3, wherein
- the capacitor includes a plurality of laminated capacitor layers, each of the laminated capacitor layers has the first electrode, the capacitor insulating film and the second electrode, and the first electrode and the second electrode of each of the laminated capacitor layers are electrically connected to each other, respectively.
11. The semiconductor device manufacturing method as claimed in claim 4, wherein the capacitor includes a plurality of laminated capacitor layers, each of the laminated capacitor layers has the first electrode, the capacitor insulating film and the second electrode, and the first electrode and the second electrode of each of the laminated capacitor layers are electrically connected to each other, respectively.
12. The semiconductor device manufacturing method as claimed in claim 1, wherein
- the capacitor insulating film is any one of a tantalum oxide film, an aluminum oxide film, an hafnium oxide film, and a laminated film of an aluminum oxide film and an hafnium oxide film.
13. The semiconductor device manufacturing method as claimed in claim 1, wherein
- the protection insulating film is a silicon oxide film.
14. The semiconductor device manufacturing method as claimed in claim 10, wherein
- the protection insulating film is a silicon oxide film.
15. A semiconductor device including a capacitor comprising:
- a first electrode provided on a semiconductor substrate;
- a capacitor insulating film provided on a side surface of the first electrode; and
- a second electrode provided on a surface of the capacitor insulating film facing the first electrode, wherein
- the capacitor insulating film has a first part along the side surface of the first electrode, and a second part extending substantially in parallel with the semiconductor substrate from a lower end of the first part in a direction of the second electrode.
16. The semiconductor device as claimed in claim 15, wherein
- the first electrode is a plate electrode, and the second electrode is a storage electrode.
17. The semiconductor device as claimed in claim 16, wherein
- the capacitor includes a plurality of laminated capacitor layers, each of the laminated capacitor layers has the first electrode, the capacitor insulating film and the second electrode, and the first electrode and the second electrode of each of the laminated capacitor layers are electrically connected to each other, respectively.
18. The semiconductor device as claimed in claim 15, wherein
- a cap insulating film is provided on the first electrode, and an upper end of the capacitor insulating film covers at least a part of the side surface of the cap insulating film.
19. The semiconductor device as claimed in claim 16, wherein
- a cap insulating film is provided on the first electrode, and an upper end of the capacitor insulating film covers at least a part of the side surface of the cap insulating film.
20. The semiconductor device as claimed in claim 17, wherein
- a cap insulating film is provided on the first electrode, and an upper end of the capacitor insulating film covers at least a part of the side surface of the cap insulating film.
Type: Application
Filed: Apr 5, 2006
Publication Date: Feb 8, 2007
Applicant:
Inventor: Hiroyuki Uchiyama (Tokyo)
Application Number: 11/397,813
International Classification: H01L 29/94 (20060101); H01L 21/20 (20060101);