Manufacturing method of semiconductor integrated circuit device

Details Manufacturing method of semiconductor integrated circuit device Manufacturing method of semiconductor integrated circuit device

2000-12-28

2003-08-19

Chaudhuri, Olik (Department: 2815)

Semiconductor device manufacturing: process

Chemical etching

Vapor phase etching

C438S003000

Reexamination Certificate

active

06607988

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor integrated circuit device and to a method of manufacture thereof; and more, particularly, the invention relates to a structure wherein a conductor film made of a metal or an alloy containing Ru (ruthenium) as a principal component is formed inside of a hole (redess) which has been formed in an insulating film with a high aspect ratio, and to a technique effective when adapted to the method of manufacture of the structure.
Japanese Patent Application Laid-Open Hei 8(1996)-78396 (Tokashiki, et al.) discloses a technique for the manufacture of a semiconductor device which comprises dry etching of an Ru oxide by using a plasma formed from a gas mixture containing at least one substance selected from the group consisting of halogen gases, containing at least one of fluorine gas, chlorine gas, bromine gas and iodine gas, and hydrogen halides, and an oxygen gas or an ozone gas.
Japanese Patent Application Laid-Open No. Hei 11(1999)-50163 (Shindo, et al.) discloses a process for preparing a high purity ruthenium material for thin film formation, which comprises blowing an ozone-containing gas into a crude ruthenium powder while adding thereto hypochlorous acid, thereby forming ruthenium tetraoxide, allowing the resulting ruthenium tetraoxide to absorb to a hydrochloric acid solution, evaporating the resulting solution to dryness and roasting the resulting RuOCl
3
crystals in a hydrogen atmosphere.
Rainer Loessberg and Ulrich Mueller disclose in “Zeitschrift Fuer Naturforschung, Section B, Chemical Sciences, Vol, 36B, No.3, 1981, pp395”, a process for preparing pure ruthenium tetraoxide by reacting ruthenium and ozone at room temperature. The following is the outline of the process: “RUO
4
can be synthesized from an Ru metal and zone at room temperature. This process makes it possible to prepare pure RuO
4
directly without causing a problem of separation of water which occurs in the standard preparing process. In the well known synthesizing process of an Ru (VIII) oxide, an aqueous solution of a ruthenium compound (such as RuCl
3
, RUO
2
or RuO
4
) is mixed with an oxidizing agent (such as BrO
3
−
, IO
4
−
or MnO
4
−
), followed by distillation or extraction of the resulting RUO
4
. Then, a subsequent operation for separating water present in the system, which is accompanied with some difficulty, is required, which lowers the yield. We have found a simple synthesis process of reacting metal ruthenium with ozone at room temperature. Ozone must be free of oxygen, because unless so, the reaction becomes markedly slow (presumably because of immobilization owing to the formation of a lower bxide of ruthenium). For this purpose, a U-tube for feeding an O
2
/O
3
mixture from an ozonizer is filled in advance with dried silica gel and it is maintained at −78° C. The silica gel becomes dark blue when O
3
is adsorbed thereto, but O
2
is not adsorbed to it. The condenser is gradually distanced from the U-tube and dry nitrogen is allowed to pass therethrough slowly, whereby ozone is released. An N
2
/O
3
mixed gas is introduced into the tube of about 30 cm long and 3 cm wide having therein finely dispersed Ru powders (particle size: 60 &mgr;m) uniformly. The RuO
4
thus formed is carried by a gas flow and is separated as gold crystals in the condenser of −78° C. For preventing contamination by water, the apparatus is filled with completely dried nitrogen from the beginning of the reaction. Oxygen to be introduced into the ozonizer must be dry so that a drying tube filled with P
2
O
5
is connected with the inlet of the separating condenser. The Ru filled in the tube is converted at a stoichiometric ratio so that an excess amount of O
3
is required. The same amount of RuO
4
is available when the time spent is the same”.
Watari, et al. in “Journal of Nuclear Science and Technology, 28, No. 6(1986), pp 493-500”, describe the volatility of an oxide of Ru, which is one of platinum metals produced by nuclear fission, from the viewpoint of spent fuel reprocessing.
SUMMARY OF THE INVENTION
As a countermeasure against a decrease in a storage charge amount owing to microfabrication of a memory cell in large-capacity DRAMs (Dynamic Random Access Memories) after a DRAM of 256 Mbit, the constitution of a capacitor insulating film of an information storage capacitor made from a high dielectric material, such as BST ((Ba, Sr) TiO
3
), which has a dielectric constant of 50 or greater and is an ABO
3
type double oxide, that is, a perovskite type double oxide, or even from a ferroelectric substance, which has a dielectric constant of 100 or greater and contains a perovskite crystal structure, such as PZT (PbZr
x
Ti
1−x
,O
3
), PLT (PbLa
x
Ti
1−
,O
3
), PLZT, PbTiO
3
, SrTiO
3
or BaTiO
3
, is under investigation.
When a capacitor insulating film is formed from a high dielectric or ferroelectric material as in the conventional manner, conductor films for the electrode between which the high dielectric or ferroelectric material is sandwiched must be constituted from a material having a high affinity with the material. As such an electrode material, platinum metals typified by Ru and Os and conductive oxides thereof have been investigated as a candidate, and, particularly, the introduction of Ru is under way.
When Ru is used as a lower electrode material of an information storage capacitor, a step is required for forming a hole (recess) in a thick silicon oxide film, depositing an Ru film over the silicon oxide film and inside (on the side walls and bottom surface) of the hole, and etching away a portion of the Ru film over the silicon oxide film, thereby forming a lower electrode of Ru on the side walls and bottom surface of the hole.
In the conventional ion assist plasma etching using oxygen as a main etching gas, however, removal the Ru film from the upper surface of the silicon oxide film without etching away the Ru film inside of the hole is difficult and this becomes a large cause for disturbing the satisfactory formation of an information storage capacitor using Ru as a lower electrode material.
An object of the present invention is therefore to provide an etching technique which is capable of removing an Ru film outside of a hole having a high aspect ratio without etching away the Ru film inside the hole.
Another object of the present invention is to provide a technique for forming a lower electrode of an information storage capacitor inside of a hole having a markedly high aspect ratio.
The above-described and other objects, and novel features of the present invention will be apparent from the description herein and the accompanying drawings.
Among the features disclosed in the present application, typical ones will be summarized simply in the following items.
1. A manufacturing method of a semiconductor integrated circuit device according to the present invention, which comprises:
(a) forming, over the first main surface of a wafer, a first conductor film made of a metal or an alloy containing ruthenium or osmium as a principal component; and
(b) subjecting the first conductor film to isotropic dry etching in a gas atmosphere containing an ozone gas.
2. A manufacturing method of a semiconductor integrated circuit device according to the present invention, which comprises:
(a) forming, over the first main surface of a wafer, a first conductor film made of a metal or an alloy containing ruthenium or osmium as a principal component, and
(b) subjecting the first conductor film to non-plasma dry etching in a gas atmosphere containing an ozone gas.
3. A manufacturing method of a semiconductor integrated circuit device according to the present invention, which comprises:
(a) forming, over the first main surface of a wafer, a first conductor film made of a metal or an alloy containing ruthenium or osmium as a principal component,
(b) forming a first resist pattern over the first main surface of the wafer having the first conductor film formed thereover, and
(c) subjecting the first cond

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