Semiconductor device manufacturing: process – Forming schottky junction – Compound semiconductor
Reexamination Certificate
2002-08-01
2004-05-11
Rocchegiani, Renzo (Department: 2825)
Semiconductor device manufacturing: process
Forming schottky junction
Compound semiconductor
C438S570000, C438S573000, C438S580000, C438S171000, C438S190000, C438S239000
Reexamination Certificate
active
06734086
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor integrated circuit device and to a method of manufacturing the same; and, more particularly, the invention relates to an effective technique that may be applied to a method of depositing metal films or metal oxides using Chemical Vapor Deposition (CVD).
Semiconductor devices, or interconnect lines configuring a semiconductor integrated circuit device, are formed by repeating the formation of conductive films and insulating films and the photolithography and patterning of each film. One of the methods of forming these films is a CVD process that uses chemical reactions.
For example, a DRAM (Dynamic Random Access Memory) has memory cell selecting MISFETs and an information storage capacitor directly connected to the memory cell selecting MISFETs. In each memory cell, an information storage capacitor is formed by sequentially depositing a conductive layer which is to serve as a lower electrode, a capacitor dielectric layer, and a conductive layer which is to serve as an upper electrode. A study has been conducted for the use a metal film, such as Ru (ruthenium), for the lower electrode.
Such a metal film or capacitor dielectric can also be formed by CVD. For instance, Japanese Patent Laid-Open No. 246214/1997 discloses a method of forming a Ru film by CVD using Ru(DMHPD)
3
: 2,6-dimethyl 3,5-heptadione Ruthenium, as an ingredient.
Additionally, Japanese Patent Laid-Open No. 86270/1995 describes a technique for forming SrTiO
3
, to be used as a capacitor dielectric, by CVD using an organic metal as an ingredient.
SUMMARY OF THE INVENTION
The inventor has conducted research on and development of the DRAM and has been studying a variety of configurations and methods of forming the information storage capacitor.
With the miniaturization of semiconductor integrated circuit devices, the area available for forming the information storage capacitor also tends to be reduced, and so it has become difficult to secure a desired capacity. Thus, studies on materials to be used for electrodes or a capacitor dielectric material are needed in order to obtain a high capacity within a small area.
Thus, the present inventor has considered a Ru film for use as the lower electrode of the information storage capacitor and has been doing various studies on methods of forming this lower electrode. Platinum metals, such as Ru, do not generate a low dielectric constant film, like an oxynitride film, even in annealing after it is formed. Additionally, it can be formed thinly because it is a metal, and so it is considered preferable to increase the capacity.
To form the Ru film, for example, a forming method using CVD has been considered, which uses a tetrahydrofuran solution of ethoxycycldpentadienylruthenium (Ru(C
2
H
5
OC
5
H
4
)
2
) and O
2
(oxygen) as ingredients. However, the deposition utilizing such a reaction of the organic compound (ethoxycyclopentadienylruthenium) and oxygen leaves organic compounds or compounds thereof and oxygen in the Ru film, thereby to degrade the film quality of the Ru film.
Furthermore, a problem arises in that a metal layer formed under the Ru film is oxidized when high temperature annealing is performed, after forming the Ru film, in order to remove the organic compounds in the Ru film. For example, the platinum metals, such as Ru, generally have poor adhesion to insulating films like silicon oxide. Thus, a metal layer, which is to serve as an adhesive layer, is typically formed between these films to prevent peeling. However, this metal layer reacts with oxygen in the Ru film, causing it to be oxidized in the annealing described above. Consequently, a problem arises in that a conducting failure is generated between the information storage capacitor (lower electrode) and the memory cell selecting MISFETs.
It is an object of the present invention to provide a technique for enhancing the film quality of a metal film formed by CVD, such as a Ru film, which forms the lower electrode of an information storage capacitor.
Another object of the present invention is to form an excellent metal film to improve the characteristics of a semiconductor integrated circuit device in which the metal film is provided.
The aforesaid and other objects and novel features of the present invention will be apparent from the following description provided in the specification and the accompanying drawings.
Among the features and aspects of the present invention disclosed in this application, representative ones are as follows:
1. A method of manufacturing a semiconductor integrated circuit device according to the present invention has a step of forming a metal film over a semiconductor substrate, such as a Ru film configuring a lower electrode of a capacitor, by CVD using a compound of metal forming the metal film, H
2
O and a reducing agent, such as H
2
.
2. A method of manufacturing a semiconductor integrated circuit device according to the present invention has a step of forming a metal film over a semiconductor substrate, such as a Ru film configuring a lower electrode of a capacitor, or a Cu film configuring interconnect lines, by CVD using a compound of metal forming the metal film, H
2
O and a reducing agent, such as H
2
, at a predetermined temperature. Additionally, when using H
2
, the method has the step of forming the metal film under a condition such that a ratio of partial pressure of the H
2
O to the H
2
([H
2
O]/[H
2
]) becomes smaller than a ratio of H
2
O to H
2
([H
2
O]eq/[H
2
]eq) when a system
1
(an oxide of metal forming the metal film+H
2
) and a system
2
(a metal forming the metal film+H
2
O) are in equilibrium at the predetermined temperature.
3. A method of manufacturing a semiconductor integrated circuit device according to the present invention has a step of forming a metal oxide film over a semiconductor substrate, such as a tantalum oxide film, to serve as a capacitor dielectric element of a capacitor, by CVD using a compound of metal forming the metal oxide film, H
2
O and a reducing agent, such as H
2
, at a predetermined temperature. Furthermore, when using H
2
, the method has the step of forming the metal oxide film under a condition such that a ratio of partial pressure of the H
2
O to the H
2
([H
2
O]/[H
2
]) becomes greater than a ratio of H
2
O to H
2
([H
2
O]eq/[
2
]eq) when a system
1
(an oxide of metal forming the metal oxide film+H
2
) and a system
2
(a metal forming the metal oxide film+H
2
O) are in equilibrium at the predetermined temperature.
4. A method of manufacturing a semiconductor integrated circuit device according to the present invention involves provision of a second metal film (Ru film or Cu film) over a first metal film or first metal nitride film overlaying a semiconductor substrate, such as a W film or WN film, to serve as an adhesive layer or barrier layer, and the method has a step of forming the second metal film by CVD using a compound of metal forming the second metal film, H
2
O and a reducing agent, such as H
2
, at a predetermined temperature. Moreover, when using H
2
, there is a step of forming the second metal film under a condition that a ratio of partial pressure of the H
2
O to the H
2
([H
2
O]/[H
2
]) becomes smaller than a ratio of H
2
O to H
2
([H
2
O]eq/[H
2
]eq) when a system
1
(an oxide of metal forming the first metal film or first metal nitride film+H
2
) and a system
2
(a metal forming the first metal film or first metal nitride film+H
2
O) are in equilibrium at the predetermined temperature.
5. A method of manufacturing a semiconductor integrated circuit device in accordance with the present invention involves the provision of a second metal oxide film (a tantalum oxide film to be a capacitor dielectric) over a first metal film or first metal nitride film overlaying a semiconductor substrate, such as a W film or WN film, serving as a barrier layer or a Ru film configuring
Antonelli Terry Stout & Kraus LLP
Renesas Technology Corp.
Rocchegiani Renzo
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