Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – To form ohmic contact to semiconductive material
Reexamination Certificate
2002-02-11
2003-04-15
Niebling, John F. (Department: 2812)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
To form ohmic contact to semiconductive material
C438S625000, C438S629000, C438S642000, C438S648000, C438S652000, C438S656000, C438S658000, C438S680000, C438S685000
Reexamination Certificate
active
06548398
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a method of manufacturing a semiconductor device and a unit of manufacturing a semiconductor device, wherein a metallic circuit is formed in a recess portion, which includes: a minute through-hole for connecting circuit layers, a minute contact-hole for connecting a circuit layer and a diffusion layer (doped layer) such as a transistor device, and a narrow groove for forming a metallic wire. In particular, this invention relates to a method of manufacturing a semiconductor device and a manufacturing unit for carrying out a part of the method, wherein a good filling can be achieved by controlling a deposition characteristic of an early stage of a deposition process, in which a metal for a circuit is deposited on a base-metal film, which has been pre-deposited in a recess portion and on a plane in which the recess portion is formed, by using a CVD (Chemical Vapor Deposition) method. The term of base-metal film used in the specification also includes any base-metal compound film.
BACKGROUND OF THE INVENTION
As a semiconductor device being a semiconductor integrated circuit, for example an IC or an LSI, is made more minute, a contact-hole for connecting an impurity-diffusion layer (doped layer) and a metallic-circuit layer and/or a through-hole for connecting metallic-circuit layers, which holes are formed on a surface of a semiconductor substrate, are also made more minute. That is, an aspect ratio (a ratio of an open width with respect to a depth of the hole) of the contact-hole and/or the through-hole is increased.
A method of depositing a metal for a circuit such as an aluminum alloy by means of a sputtering method is conventionally used as an art of obtaining an electric connection by filling such a hole with a metal for a circuit. However, it is difficult to satisfactorily deposit the metal for a circuit in such a minute hole by means of a sputtering method. Thus, it has been studied to adopt a CVD method that is superior in a deposition characteristic into a minute hole.
The CVD method includes: a selective deposition CVD method (selective), wherein a non-electric-conductive area (for example, a surface of an insulating layer formed on a base-metal circuit) and a electric-conductive area (for example, a surface of a base-metal film exposed at a bottom of a hole formed in the insulating layer) are formed on a surface of a substrate, and then a metal for a circuit is deposited only on the electric-conductive area; and a whole-surface deposition CVD method (blanket), wherein a base-metal film such as a titanium nitride film is formed on the whole surface of the substrate including the inside of the hole and the surface of the insulating layer around the hole, and then a metal for a circuit is deposited on the whole surface.
Among them, the whole-surface deposition CVD method has an advantage that a sensitiveness to a state of the surface of the substrate with respect to the deposition is low, so that the method can be used stably as a mass-production art. In addition, the whole-surface deposition CVD method has an advantage that a metal film for a circuit deposited on the insulating layer outside the hole can be patterned to be used as a or more metallic wires.
Tungsten that can be made from tungsten fluoride (WF
6
) and aluminum that can be made from any organic aluminum compound are typical as an electric conductive metal that can be deposited by means of the above CVD methods. In particular, aluminum is superior because its electric resistance is one third as much as that of tungsten so that a low-resistance circuit element can be formed. In addition, copper and gold whose electric resistance is further lower than that of aluminum can be deposited by means of the CVD methods.
Following two methods are known as an art to fill a hole with aluminum by means of the whole-surface deposition CVD method.
In a first method, a deposition unit is used wherein a CVD reacting chamber and a sputtering chamber are connected to each other via a transferring chamber that is shut off from the atmosphere. At first, titanium nitride is deposited on the whole surface of a substrate, in which a hole has been formed, in the sputtering chamber. Then, the substrate is transferred into the CVD chamber through the transferring chamber without being exposed to the atmosphere. Next, aluminum is deposited by means of a CVD method using triisobutyl aluminum (for example, see U.S. Pat. No. 5,008,217). However, in practice, the sputtering chamber and the CVD chamber are very different in their using gas and their operating pressure. Thus, it is technically difficult to both form and use the unit in which the sputtering chamber and the CVD chamber are united.
In a second method, titanium nitride is deposited on the whole surface of a substrate, in which a hole has been formed, by means of a sputtering method. The substrate is introduced into a CVD unit. Then, the substrate is allowed to come in contact with the atmosphere. After that, aluminum is deposited by means of a CVD method using dimethyl-aluminum-hydride (for example, see 1993 VLSI Multilevel Interconnection Conference Symposium p.463). In the case, if a substrate temperature at a CVD process is set to a value that can achieve a high deposition rate, aluminum deposited on the insulating layer outside the hole may cover an opening at an upper portion of the hole, before the minute hole is filled up. That is, a hollow void may be formed in the hole, so that a good filling can not be achieved. Thus, in order to achieve a good filling, it is necessary to lower the substrate temperature at the CVD process. However, in that case, the deposition rate is also lowered, so that the efficiency of the mass production is lowered.
On the other hand, the following method is known regarding the case wherein a hole is filled with tungsten by means of the selective deposition CVD method.
In this method, an unit is used wherein a cleaning chamber and a CVD chamber are connected to each other via a transferring chamber that is shut off from the atmosphere. At first, a surface such as a metallic surface exposed at a bottom of the hole is cleaned by plasma including hydrogen and/or halogen gas in the cleaning chamber. The substrate is transferred into the CVD chamber through the transferring chamber without being exposed to the atmosphere. After that, tungsten is deposited selectively only in the hole by means of a CVD method using tungsten fluoride. For example, U.S. Pat. No. 5,043,299 discloses an art to remove contaminants such as water vapor or any oxide attached in the atmosphere, which may obstruct the deposition of tungsten, by using plasma, regarding a surface such as a metallic surface exposed at a bottom of a hole.
In addition, when a metallic circuit is formed, a conventional method has been used wherein: a metal for a circuit such as an aluminum alloy is deposited on the whole upper surface of a base insulating layer by means of a sputtering method, an unnecessary part thereof is removed by means of a photo lithographic art and a dry etching art, and hence a metallic circuit layer including a desired circuit pattern is formed. However, as the metallic circuit becomes so minute that it becomes more difficult to carry out the dry etching process to the circuit layer, another method has been proposed wherein: narrow grooves corresponding to a metallic circuit pattern (grooves for a circuit) are formed in the surface of the insulating layer in advance, and a metal for a circuit is formed in the grooves (for example, see U.S. Pat. No. 4,789,648). In the case too, it is preferable that a metal for a circuit for forming a circuit layer is deposited by means of a CVD method superior in an ability to fill narrow grooves therewith.
In addition, as the JP publication No.6-35657 discloses, there is another method of depositing an aluminum film, wherein a surface activation layer of a hydroxyl group (in which a hydrogen ion in the hydroxyl group is replaced with an organic, inorganic or organic-metallic ligand group or wi
Gurley Lynne A.
Niebling John F.
Smith , Gambrell & Russell, LLP
Tokyo Electron Limited
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