JP2003318173A - Method of manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a semiconductor device, which is capable of restraining a capacitor element that uses a ferroelectric material or a high dielectric material as a capacitor insulating film from deteriorating in characteristics. <P>SOLUTION: The capacitor element 105 comprising a lower electrode 104, a ferroelectric capacitor insulating film 106, and an upper electrode 107 is formed on a first protective insulating film 101 on a semiconductor substrate 103 where a transistor 102 is formed. Then, a second protective insulating film 108 is formed so as to cover the capacitor element 105. Then, the substrate 103 and the others are subjected to a thermal treatment in a vacuum. A first wiring layer 110 is formed so as to be electrically connected to the transistor 102 and the capacitor element 105 through the intermediary of a contact hole 109 provided to the second protective insulating film 108. Then, an inter-wiring layer insulating film 111 is formed to cover the first wiring layer 110. Then, the semiconductor device is subjected to a thermal treatment in a vacuum. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device having a built-in capacitive element having a ferroelectric film or a high dielectric film as a capacitive insulating film.

[0002]

2. Description of the Related Art In recent years, with advances in speeding up and low power consumption of microcomputers and the like, consumer electronic devices have become more sophisticated, and the semiconductor devices used and the miniaturization of their semiconductor elements have rapidly become smaller. It is progressing. On the other hand, along with this, unnecessary radiation, which is electromagnetic noise generated from electronic devices, has become a big problem. As a measure for reducing the unnecessary radiation, a dielectric material having a high dielectric constant (hereinafter simply referred to as a high dielectric material) is used. A technique for incorporating a large-capacity capacitive element serving as a capacitive insulating film into a semiconductor integrated circuit device or the like has been attracting attention.

Further, as the dynamic RAM is highly integrated, a technique of using a high dielectric material as a capacitive insulating film instead of the conventional silicon oxide or silicon nitride has been widely studied. Furthermore, research and development on a ferroelectric film having a spontaneous polarization characteristic have been actively conducted with the aim of putting a non-volatile RAM capable of high-speed write / read with a low operating voltage, which has never been seen. The most important issue for realizing these semiconductor devices is to develop a process capable of realizing multilayer wiring without deteriorating the characteristics of the capacitive element.

One of the problems in forming the multi-layer wiring is deterioration of polarization characteristics of the ferroelectric film due to diffusion of water contained in the interlayer insulating film. Although the deterioration mechanism has not been clarified yet, moisture in the insulating film reacts with wiring materials such as Al and Ti to generate hydrogen,
The theory that the ferroelectric or high-dielectric element, which is an oxide, is reduced and the characteristics are deteriorated is promising. In any case, if there is residual moisture in the insulating film, heat treatment such as wiring process may cause deterioration of dielectric strength of ferroelectric or high dielectric thin film or deterioration of polarization characteristic of ferroelectric. Process measures have been needed.

A conventional method of manufacturing a semiconductor device will be described below with reference to the drawings. 4 (a)-(d)
FIG. 7A is a process sectional view showing the manufacturing method of the conventional semiconductor device.

A conventional method of manufacturing a semiconductor device will be described below. First, as shown in FIG. 4A, the first protective insulating film 1 is formed on the semiconductor substrate 3 on which the transistor 2 and the element isolation oxide film 15 are formed, and on the first protective insulating film 1. A lower electrode 4 for a capacitive element made of a platinum film or the like is formed by a sputtering method or a vapor deposition method, and then a capacitive insulating film 6 made of a high dielectric material or a ferroelectric material is formed by a metal organic chemical vapor deposition method or a sputtering method. And the upper electrode 7 for a capacitor element made of a platinum film or the like is formed by the sputtering method, and finally each film is processed into a desired shape by etching to form the capacitor element 5.

Next, as shown in FIG. 4B, the capacitive element 5
As the second protective insulating film 8 for covering the surface, a silicon oxide film (hereinafter, abbreviated as ozone TEOS film) using ozone as an oxidizing agent and TEOS (Tetraethoxysilane) is used under atmospheric pressure CVD.
After forming by the method, then the transistor (integrated circuit)
2 and a contact hole 9 to the capacitor 5 is formed,
Further, the first wiring layer 10 is formed by a sputtering method or the like, and further, the first wiring layer 10 is processed into a desired shape so as to electrically connect the transistor (integrated circuit) 2 and the capacitive element 5.

Next, as shown in FIG. 4C, a wiring interlayer insulating film 11 is formed. Here, the wiring interlayer insulating film 11 is also
Using ozone as an oxidant, TEOS (Tetraethoxysilane)
Is used to form a silicon oxide film (hereinafter referred to as an ozone TEOS film) by an atmospheric pressure CVD method. Subsequently, a via hole 12 is formed through the wiring interlayer insulating film 11 to the first wiring layer 10, a second wiring layer 13 is further formed by a sputtering method, etc., and then the first wiring layer 10 is electrically connected. The second wiring layer 13 is processed into a desired shape so as to be electrically connected.

Finally, as shown in FIG. 4 (d), a moisture-resistant material formed by a plasma CVD method in order to prevent water from entering the capacitive element 5, the first wiring layer and the second wiring layer. A third protective insulating film 14 such as a high silicon nitride film is formed.

[0010]

However, in the above-mentioned conventional manufacturing method, the water generated when the ozone TEOS film is formed as the second protective insulating film 8 and the wiring interlayer insulating film 11 by the atmospheric pressure CVD method is ozone. TEOS film absorbs,
There is a problem in that this moisture diffuses into the capacitive element during the heat treatment in the subsequent steps, causing characteristic deterioration.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a method of manufacturing a semiconductor device capable of suppressing characteristic deterioration of a capacitive element having a ferroelectric or high dielectric as a capacitive insulating film. To do.

[0012]

In order to achieve this object, a method of manufacturing a semiconductor device according to the present invention comprises a method of heating an insulating film covering a ferroelectric capacitor element or a high dielectric capacitor element and heating it in vacuum. Perform processing.

In the method for manufacturing a semiconductor device of the present invention, it is preferable that the heat treatment performed in vacuum is performed at a temperature not higher than the maximum temperature of heat treatments performed after the insulating film is formed.

Further, in the semiconductor device manufacturing method of the present invention, the heat treatment performed in vacuum is preferably performed at 450 ° C. or lower.

In the method for manufacturing a semiconductor device of the present invention, the heat treatment performed in vacuum is preferably performed at a pressure of 250 Pa or less.

In the method of manufacturing a semiconductor device of the present invention, the insulating film is preferably a silicon oxide film using ozone as an oxidant and TEOS as a raw material, or a silicon oxide film to which phosphorus is added.

With such a structure, moisture is released into the vacuum, the moisture in the ozone TEOS film is reduced, and the moisture from the ozone TEOS film to the capacitive element during the heat treatment in the subsequent steps is reduced. It is possible to reduce diffusion and suppress characteristic deterioration.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

FIGS. 1A to 1D are process sectional views showing a method of manufacturing a semiconductor device having a built-in capacitor according to an embodiment of the present invention.

A method of manufacturing a semiconductor device according to the embodiment of the present invention will be described below.

First, as shown in FIG. 1A, a first protective insulating film 101 is formed on a semiconductor substrate 103 having a transistor 102 and an element isolation oxide film 115 formed thereon. A capacitive element lower electrode 104 made of a platinum film or the like is formed on 101 by a sputtering method or a vapor deposition method, and subsequently a capacitive insulating film 1 made of a high dielectric material or a ferroelectric material.
06 is formed by a metal organic chemical vapor deposition method, a sputtering method, or the like, and is further formed of a platinum film or the like.
After forming 07 by a sputtering method, finally, each film is processed into a desired shape by etching to form the capacitor 105.

Next, as shown in FIG. 1B, the capacitive element 1
As a second protective insulating film 108 that covers 05, ozone TE
The OS film is formed by the atmospheric pressure CVD method. Here, in the present invention, the semiconductor substrate 103 is subjected to heat treatment at 300 ° C. in a vacuum with a pressure of 250 Pa, and the second protective insulating film 10 is formed.
The moisture in the film of No. 8 is released into vacuum.

After that, subsequently, a transistor (integrated circuit)
Contact hole 10 to 102 and capacitor 105
9, the first wiring layer 110 is further formed by a sputtering method or the like, and the first wiring layer 110 is formed into a desired shape so as to electrically connect the transistor (integrated circuit) 102 and the capacitor 105. To process.

Next, as shown in FIG. 1C, a wiring interlayer insulating film 111 is formed. Here, the wiring interlayer insulating film 111
In this case, the ozone TEOS film is formed by the atmospheric pressure CVD method. Here, further, in the present invention, the semiconductor substrate 10
3 is heat-treated at 300 ° C. in a vacuum with a pressure of 250 Pa to release moisture in the film of the wiring interlayer insulating film 111 into the vacuum.

Subsequently, a via hole 112 is formed through the wiring interlayer insulating film 111 to the first wiring layer 110, a second wiring layer 113 is further formed by a sputtering method, etc., and then the first wiring layer is formed. Second to connect 110 electrically
The wiring layer 113 is processed into a desired shape. Then, in order to prevent corrosion of the processed second wiring layer 113, heat treatment is performed for 30 minutes in a nitrogen atmosphere at 350 ° C.

Finally, as shown in FIG. 1D, the capacitive element 1
05, by the plasma CVD method in order to prevent water from entering the first wiring layer 110 and the second wiring layer 113.
A third protective insulating film 114 such as a silicon nitride film having high moisture resistance formed at a film forming temperature of 00 ° C. is formed.

Next, the measurement results regarding the amount of temperature-programmed desorption of water contained in the ozone TEOS film formed by the atmospheric pressure CVD method will be described with reference to FIG.

The horizontal axis of FIG. 2 represents temperature, and the vertical axis represents the amount of water released at that temperature. These relationships correspond to the strength of water adsorption. As shown in FIG.
Regarding the peak temperature at which the water adsorbed on the TEOS film desorbs, the first peak is 350 ° C. to 450 ° C. and the second peak is 65 ° C.
It is between 0 ° C and 750 ° C. Of these, the moisture corresponding to the second peak is adsorbed to the ozone TEOS film with a sufficiently strong adsorbing power, so that it is 450 in the wiring manufacturing process of the semiconductor device.
It is considered that the heat treatment at a temperature of ℃ or less has almost no effect on the characteristics. On the other hand, the first peak is 350 ℃ ~
Since the temperature is 450 ° C., the adsorbed water is released, and there is a high risk that the characteristics will deteriorate due to the diffusion of water into the capacitive element.

The above-mentioned measurement results regarding the temperature-programmed desorption amount of the water contained in the ozone TEOS film are obtained under the atmospheric pressure. Considering that water contained in the ozone TEOS film can be desorbed at a temperature lower than the peak of 1, after forming the ozone TEOS film by the atmospheric pressure CVD method as the second protective insulating film 108 and the wiring interlayer insulating film 111, 250 Pa for the purpose of reducing moisture in the ozone TEOS film
The semiconductor substrate at 200 ° C for 120 minutes in the vacuum of
The moisture in the film was released in vacuum.

The results will be described with reference to FIG.

Here, the characteristics of the capacitive element on the semiconductor substrate which was heat-treated in vacuum after forming the ozone TEOS film and the characteristics of the capacitive element on the semiconductor substrate which was not heat-treated in vacuum were described. The residual polarizability of the ferroelectric capacitors was compared.

FIG. 3 shows the residual polarization amounts of the capacitive element on the semiconductor substrate which was heat-treated in vacuum after forming the TEOS ozone film and the capacitive element on the semiconductor substrate which was not heat-treated in vacuum. Shown respectively.

Comparing the capacitive element on the semiconductor substrate which is heat-treated in vacuum after forming the ozone TEOS film with the capacitive element on the semiconductor substrate which is not heat-treated in vacuum, heat treatment in vacuum is performed. It can be seen that the characteristics of the capacitive element on the semiconductor substrate subjected to the above are improved. This is Ozone TE
Since moisture contained in the OS film is desorbed at a lower temperature in vacuum than in the atmosphere, moisture present in the second protective insulating film and the ozone TEOS film as the wiring interlayer insulating film is removed. It can be considered that this is because the amount of water is further reduced, and the diffusion of water into the capacitor during the heat treatment in the subsequent steps can be further reduced, and the characteristic deterioration of the capacitor is suppressed.

In the above embodiment, ozone TEOS is used.
Although the case where the film is used as the second protective insulating film and the wiring interlayer insulating film has been described, needless to say, even if the ozone TEOS film is used as only one of the films, the same applies when the heat treatment is performed in a vacuum thereafter. The effect of can be obtained.

In this embodiment, the ozone TEOS film is used as the second protective insulating film and the wiring interlayer insulating film,
Moreover, the case where the wiring interlayer insulating film is one layer has been described.
The same holds true when it is used for a wiring interlayer insulating film which is an upper layer in a multilayer wiring.

In this embodiment, the case where the ozone TEOS film is used as the second protective insulating film and the wiring interlayer insulating film has been described, but a silicon oxide film containing phosphorus or a silicon oxide film containing boron is also high. Since they have water absorbency, when these are used as the second protective insulating film and the wiring interlayer insulating film, the same effect as that of the ozone TEOS film can be obtained by the heat treatment in vacuum.

[0037]

According to the method of manufacturing a semiconductor device of the present invention, the moisture in the film of the ozone TEOS film can be reduced by the heat treatment in vacuum, and the capacitance element can be removed during the heat treatment in the subsequent steps. It is possible to reduce the diffusion of moisture and suppress the characteristic deterioration of the capacitive element.

[Brief description of drawings]

FIG. 1 is a cross-sectional view in order of steps of a method for manufacturing a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a temperature rise desorption amount of water from an ozone TEOS film.

FIG. 3 is a characteristic diagram showing a difference in remanent polarization amount between the embodiment of the present invention and a conventional example.

FIG. 4 is a cross-sectional view in order of steps of a method for manufacturing a semiconductor device in a conventional example.

[Explanation of symbols]

1 First protective insulating film 2 transistors 3 Semiconductor substrate 4 Lower electrode for capacitive element 5 capacitive elements 6 Capacitance insulating film 7 Upper electrode for capacitive element 8 Second protective insulating film 9 contact holes 10 First wiring layer 11 Wiring interlayer insulation film 12 beer hall 13 Second wiring layer 14 Third protective insulating film 15 Element isolation oxide film 101 First protective insulating film 102 transistor 103 semiconductor substrate 104 Lower electrode for capacitive element 105 Capacitive element 106 Capacitance insulating film 107 Upper electrode for capacitance element 108 Second protective insulating film 109 contact holes 110 First wiring layer 111 Wiring interlayer insulation film (vacuum heat treatment) 112 beer hall 113 Second wiring layer 114 Third protective insulating film 115 Device isolation oxide film

Claims (5)

[Claims] 1. A method of manufacturing a semiconductor device, comprising: performing heat treatment in a vacuum after forming an insulating film covering a ferroelectric capacitor element or a high dielectric capacitor element. 2. The method for manufacturing a semiconductor device according to claim 1, wherein the heat treatment performed in the vacuum is performed at a temperature not higher than a maximum temperature of heat treatments performed after the insulating film is formed. 3. The heat treatment performed in the vacuum is 300 ° C.
The method for manufacturing a semiconductor device according to claim 1, wherein the method is performed as follows. 4. The heat treatment performed in the vacuum is performed at a pressure of 25.
The method for manufacturing a semiconductor device according to claim 1, wherein the method is performed at 0 Pa or less. 5. The insulating film uses ozone as an oxidant and TE
2. The method of manufacturing a semiconductor device according to claim 1, wherein the silicon oxide film is made of OS as a raw material, the silicon oxide film is doped with phosphorus, or the silicon oxide film is doped with boron.