JP2001127269A - Semiconductor device and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase a surface area by controlling the surface morphology of a storage node electrode at a capacity part. SOLUTION: A capacity part comprising at least a capacity insulating film 2 and a storage node electrode 1 contacting to the capacity insulating film 2 is provided. Here, a high melting-point metal nitride film is formed as the storage node electrode 1 into a form having a specified surface morphology, with the capacity insulating film 2 formed on the storage node electrode 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor device and a method of manufacturing the same, and more particularly, to a semiconductor device for increasing a surface area of a storage node electrode in a capacitance portion and a method of manufacturing the same.

[0002]

2. Description of the Related Art DRAM (Dynamic Land)
2. Description of the Related Art In a memory product such as a m Access Memory, it is necessary to reduce the size of a capacitance portion formed therein while securing a necessary capacitance with the increase in integration.

[0003] In response to such demands, the insulating film of the capacitor has been thinned, and a capacitor using a high dielectric constant insulating film instead of the conventional silicon oxide film or silicon nitride film has been proposed. And perovskite-type titanates such as barium titanate and strontium titanate have attracted attention.

On the other hand, from the viewpoint of voltage dependence of capacitance, a high-melting point metal material such as tungsten is used as the storage node electrode of the capacitance portion, and the equivalent oxide film thickness is reduced. Proposed.

Further, when a high melting point metal material is used as the storage node electrode of the ultra-fine capacitance portion, a formation technique having excellent step coverage such as a chemical vapor deposition method is required.

Here, a method of manufacturing a capacitor element using a conventional cylindrical storage node electrode will be described with reference to FIG.

First, a cylindrical storage node electrode 81
To form an interlayer insulating film 8 on the contact hole buried with titanium / titanium nitride 82 and tungsten 83.
Then, a cylindrical hole is formed by PR / dry etching (FIG. 8A).

Next, as the storage node electrode 81,
A tungsten film using WF ₆ gas is formed by a chemical vapor deposition method, and a protective PR 85 is deposited (FIG.
(B))).

Subsequently, the tungsten film formed on the interlayer insulating film 84 is removed by protection PR / dry etching, and the protection PR 85 in the cylindrical hole is removed.
Thus, the cylindrical storage node electrode 81 is formed (FIG. 8C).

Next, a capacitance insulating film 86 is formed on the cylindrical storage node electrode 81, and thereafter, a plate electrode 87 is formed.
Is formed (FIG. 8D). In this way, a capacitance element using the cylindrical storage node electrode 81 is completed.

[0011]

However, WF ₆
When a tungsten film using a gas is formed by a chemical vapor deposition method, the crystallinity of the tungsten film itself and the reactivity of the WF ₆ gas are so strong that it is difficult to suppress the film surface morphology. There is a problem that it is difficult to form a state.

The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to increase the surface area by controlling the surface morphology of a storage node electrode in a capacitor.

[0013]

According to the present invention, there is provided a method of manufacturing a semiconductor device having at least a capacitor insulating film and a capacitor having a storage node electrode in contact with the capacitor insulating film. Then, a refractory metal nitride film is formed as a storage node electrode in a shape having a predetermined surface morphology, and a capacitor insulating film is formed on the storage node electrode.

Preferably, the refractory metal nitride film as the storage node electrode is formed by a chemical vapor deposition method.

Here, when forming the nitrided refractory metal film as the storage node electrode by a chemical vapor deposition method,
Using a halogen-based high melting point metal gas and an ammonia gas, a halogen-based high melting point metal gas and an ammonia gas are introduced into the reaction vessel so as to be 1/20 to 10 with respect to ammonia, and the growth temperature is set to 300 to 600 ° C. And the reaction pressure is set within the range of 0.01 to 5.0 Torr.

In this case, the halogen-based high melting point metal gas is used.
Is at least WF₆, MoCl ₅, TaCl₅as well as
TiCl₄Selected from

The surface area of the nitrided high melting point metal film having the morphology is approximately 1.2 to 2.5 times the surface area of the nitrided high melting point metal film before forming the morphology.

Further, the refractory metal nitride film serving as the storage node electrode may include at least tungsten nitride,
It is selected from molybdenum nitride, tantalum nitride and titanium nitride.

Further, the refractory metal nitride film as the storage node electrode may be formed directly on the interlayer insulating film.

Preferably, the interlayer insulating film is a silicon oxide film.

Further, a heat treatment is performed on the storage node electrode using a nitriding gas. The heat treatment using the nitriding gas is performed to reduce the contact resistance of the storage node electrode.

The heat treatment using the nitriding gas is preferably performed at a temperature of 700 ° C. or less. The nitriding gas is
It is preferably ammonia gas.

Further, a heat treatment for densifying the capacitor insulating film is performed. This heat treatment for densifying the capacitor insulating film is performed to improve the leakage current characteristics.

Further, a plate electrode is formed on the capacitance insulating film. It is preferable that the capacitor insulating film is an insulating film having a high dielectric constant.

Further, it is preferable that the capacitive insulating film is formed by a chemical vapor deposition method.

The capacitance insulating film is preferably made of tantalum oxide. Alternatively, the capacitance insulating film is made of perovskite titanate. The perovskite titanate is barium titanate or strontium titanate.

Further, according to the present invention, in a semiconductor device having at least a capacitance portion having a capacitance insulating film and a storage node electrode in contact with the capacitance insulating film, a nitride capable of controlling surface morphology is provided as a storage node electrode. Use a high melting point metal material.

The nitrided high melting point metal material is at least
It is selected from tungsten nitride, molybdenum nitride, tantalum nitride and titanium nitride.

[0029]

FIG. 1 is a schematic sectional view showing an example of a semiconductor device (DRAM cell) manufactured by a method of manufacturing a semiconductor device according to the present invention.

An n-well 8 is formed in the surface region of the p-type silicon substrate 7, and a first p-well 9 is formed in the n-well 8. In the other surface region of the p-type silicon substrate 7, a second p-well 10 is formed.

The first p-well 9 and the second p-well 10 are separated by an n ⁺ -type separation region 11 formed in the n-well 8, and these regions constitute a silicon substrate. .

The STI ( S allow) on the main surface of this silicon substrate
T rench I solation) each element 12 with an insulating isolated activated region 17 is formed.

In the first p-well 9, transistors 100 are formed in a large number of memory cells, and these transistors 100 are entirely covered with a first interlayer insulating film 13.

On the first interlayer insulating film 13, via a contact hole provided in the first interlayer insulating film 13, a pair of memory cells becomes a source / drain region common to each transistor 100. A bit line 21 connected to the n-type region is formed. Here, each transistor 100 has a polysilicon gate electrode 19 and a metal gate electrode 20.

The second interlayer insulating film 14 is formed so as to cover the bit line 21, and the capacitor element according to the present invention is formed on the bit line 21.

That is, the capacitance element of the cylindrical stack is
It comprises a storage node electrode 1, a capacitor insulating film 2, and a plate electrode 3. The pair of storage node electrodes 1 are connected to respective transistors 1 through contact holes 18 provided in the first and second interlayer insulating films 13 and 14.
The other source / drain region n
Connected to the mold area.

The plate electrode 3 has a pair of memory cells, each of which has a common capacitance element and is continuously formed, and its extension is covered with a second interlayer insulating film 14.
The take-out portion of the plate electrode 3 is formed by the third interlayer insulating film 15
Is electrically connected to an Al wiring 23 which is maintained at a fixed potential such as a ground potential through a through hole 22 provided in the semiconductor device.

The tungsten plug 6 is formed below the Al wiring 23 and in the through hole 22. Further, the protective film 1 is formed on the third interlayer insulating film 15.
6 are formed.

FIG. 2 is a process sectional view showing a manufacturing method according to the first embodiment of the present invention. The manufacturing method shown in FIG. 2 is applied to a portion of a capacitor element portion using one cylindrical storage node electrode shown in FIG. Corresponding.

First, in order to form the cylindrical storage node electrode 1, titanium / titanium nitride 4 and tungsten 5
A third interlayer insulating film 15 on the contact hole buried with
Is deposited, and a cylindrical hole is formed by PR / dry etching (FIG. 2A).

Next, as the storage node electrode 1, a tungsten nitride film is formed as thin as 50 nm or less by a chemical vapor deposition method using tungsten hexafluoride gas (WF ₆ ), which is a halogen-based high melting point metal gas, and ammonia gas. I do. Further, the protection PR 200 is deposited in the cylindrical hole (FIG. 2B).

Here, as a condition for forming the tungsten nitride film, a tungsten hexafluoride gas and an ammonia gas are introduced into a reaction vessel (not shown) so that the ratio becomes 1/20 or more and 10 or less with respect to ammonia. Temperature between 300 and 6
The reaction pressure was set to 0.01 to 5.0 while being set to 00 ° C.
Set to Torr. As a result, the storage node electrode 1 having a desired surface area by controlling the uneven state of the surface morphology is formed.

Further, the protective high-melting-point metal film formed on the third interlayer insulating film 15 is removed by protection PR / dry etching, and the protection PR 200 in the cylindrical hole is removed. Further, the third interlayer insulating film 15 is removed to form the cylindrical storage node electrode 1 (FIG. 2C).

In this case, in order to obtain a low contact resistance, it is desirable to perform an annealing process using a nitriding gas such as an ammonia gas. However, when the treatment is performed at a high temperature of 700 ° C. or more, the tungsten nitride film is peeled off, and therefore the annealing treatment is performed at a temperature lower than that.

Next, on the cylindrical storage node electrode 1
A tantalum oxide film is formed as the capacitance insulating film 2. Oxidation
The formation of the tantalum film is performed using ethoxy tantalum (Ta (OC₂H
₅) ₅) And chemical vapor deposition using oxygen as a raw material
It is. As a result, a tantalum oxide film having a thickness of about 10 nm is formed.
Is formed.

Further, as a densification process for improving the leak current characteristics, UV-O ₃ annealing is performed. Thereafter, a high melting point metal film such as tungsten nitride is formed as a plate electrode 3 by a chemical vapor deposition method, and a desired layer such as an interlayer insulating film is formed to form a semiconductor device of the present invention (FIG. 2D). .

Here, FIG. 3 shows an SEM photograph showing the dependence of the tungsten nitride film, which is the storage node electrode 1 formed according to the present invention, on the unevenness shape depending on the forming temperature.

FIG. 3 shows that the surface morphological state of the tungsten nitride film varies depending on the forming temperature, and that when a temperature of 450 ° C. is used, an uneven state close to a hemisphere can be formed.

Next, FIG. 4 shows the dependence of the surface area of the capacitance portion on the temperature at which the tungsten nitride film serving as the storage node electrode 1 is formed.

The reaction gas ratio is WF ₆ : NH ₃ = 10
When a tungsten nitride film was formed at a pressure of 1.0 Torr using 0:50, the surface area obtained was different depending on the formation temperature. By using 450 ° C., an increase in the surface area of about 2.5 times was observed.

FIG. 5 shows the cell capacitance value dependency of the stack height in the semiconductor device formed as described above.

Here, ○ indicates a case where a tungsten nitride film formed by a chemical vapor deposition method is applied as the storage node electrode 1, and ● indicates a chemical vapor deposition method using the conventional manufacturing method shown in FIG. 8. The results when a tungsten film or a tungsten nitride film using a flat state is applied are shown.

FIG. 5 shows that when the tungsten nitride film according to the present invention was used, the cell capacitance value with respect to the same stack height was increased about twice as compared with the case where the conventional technique was used.

In the present invention, only the tungsten nitride film has been described as the storage node electrode 1. However, the present invention can be applied to the case where other high melting point metal materials such as molybdenum nitride, tantalum nitride or titanium nitride are used. Almost the same effects as those of the first embodiment were obtained.

Further, in the present invention, only the tantalum oxide film has been described as the capacitance insulating film. However, the present invention can be applied to a case where barium titanate or strontium titanate which is a perovskite titanate is used. An effect almost equivalent to that of the first embodiment was obtained.

FIG. 6 is a process sectional view showing a manufacturing method according to the second embodiment of the present invention.

First, a titanium / titanium nitride 4 and a tungsten 5
A third interlayer insulating film 15 on the contact hole buried with
Is deposited, and a cylindrical hole is formed by PR / dry etching (FIG. 6A).

Next, as the storage node electrode 1, a tungsten nitride film is formed as thin as 50 nm or less by a chemical vapor deposition method using tungsten hexafluoride gas (WF ₆ ), which is a halogen-based high melting point metal gas, and ammonia gas. I do. Further, a protection PR 600 is deposited in the cylindrical hole (FIG. 6B).

Here, as a condition for forming the tungsten nitride film, a tungsten hexafluoride gas and an ammonia gas are introduced into a reaction vessel (not shown) so as to be 1/20 or more and 10 or less with respect to ammonia. Temperature between 300 and 6
The reaction pressure was set to 0.01 to 5.0 while being set to 00 ° C.
Set to Torr. As a result, the storage node electrode 1 having a desired surface area by controlling the uneven state of the surface morphology is formed.

Further, the nitrided high melting point metal film formed on the third interlayer insulating film 15 is removed by protective PR / dry etching. Furthermore, protection PR600 in the cylindrical hole
Is removed to form a cylindrical storage node electrode 1 (FIG. 6C).

At this time, in order to suppress film peeling and obtain a low contact resistance, an annealing treatment using a nitriding gas such as an ammonia gas is performed at a temperature of 700 ° C. or less.

Next, onto the cylindrical storage node electrode 1
A tantalum oxide film is formed as the capacitance insulating film 2. Oxidation
The formation of the tantalum film is performed using ethoxy tantalum (Ta (OC₂H
₅) ₅) And chemical vapor deposition using oxygen as a raw material
It is. As a result, a tantalum oxide film having a thickness of about 10 nm is formed.
Is formed. Also, to improve the leakage current characteristics
UV-O for densification₃Annealing is performed.

Thereafter, a high-melting point metal film such as tungsten nitride is formed as a plate electrode 3 by chemical vapor deposition, and a desired layer such as an interlayer insulating film is formed to form a semiconductor device of the present invention (FIG. 6 (d)).

FIG. 7 shows the cell capacitance value dependence of the stack height in the semiconductor device formed as described above.

Here, ○ indicates a case where a tungsten nitride film formed by a chemical vapor deposition method is applied as a storage node electrode (the present invention), and ● indicates a case where a tungsten film formed by a chemical vapor deposition method is applied (prior art). The result is shown.

FIG. 7 shows that the cell capacitance value with respect to the same stack height when the tungsten nitride film according to the present invention is used is similar to that in the case of the prior art, as in the case where the first embodiment is used. A result of about a two-fold increase was obtained.

Forming a capacitance portion of a semiconductor device using the second embodiment is a relatively stable manufacturing method as compared with the first embodiment. However,
The capacitance value formed by using the second embodiment is smaller than the case of using the first embodiment because only the inner wall portion uses the capacitance portion, but the tungsten nitride using the present invention The stack height 0.2
A cell capacitance value of 30 fF was obtained at 5 μm.

In the present invention, only the tungsten nitride film has been described as the storage node electrode 1. However, the present invention can be applied to the case where other high melting point metal materials such as molybdenum nitride, tantalum nitride or titanium nitride are used. Almost the same effects as those of the second embodiment were obtained.

Further, in the present invention, only the tantalum oxide film has been described as the capacitive insulating film. However, the present invention can be applied to a case where barium titanate or strontium titanate which is a perovskite titanate is used. An effect almost equivalent to that of the second embodiment was obtained.

[0070]

According to the present invention, by using a nitrided refractory metal material as the storage node electrode of the capacitor portion, a capacitor portion having a cell capacitance value approximately twice as large as that of the prior art can be formed. it can.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a semiconductor device (DRAM cell) manufactured by a manufacturing method of the present invention.

FIG. 2 is a schematic cross-sectional view showing a manufacturing process procedure of the semiconductor device according to the first embodiment of the present invention.

FIG. 3 is an SEM photograph showing the dependency of the formation temperature of a tungsten nitride film as a storage node electrode formed according to the first embodiment of the present invention on unevenness.

FIG. 4 is a graph showing the dependency of the surface area of the capacitance portion on the formation temperature of the storage node electrode formed according to the first embodiment of the present invention.

FIG. 5 is a graph showing a cell capacitance value dependency on a stack height of a capacitance unit formed based on the first embodiment of the present invention.

FIG. 6 is a schematic cross-sectional view illustrating a manufacturing process procedure of the semiconductor device according to the second embodiment of the present invention.

FIG. 7 is a graph showing a cell capacitance value dependency on a stack height of a capacitance unit formed based on the second embodiment of the present invention.

FIG. 8 is a schematic cross-sectional view showing a manufacturing process procedure of a conventional semiconductor device.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 storage node electrode 2 capacitance insulating film 3 plate electrode 4 titanium / titanium nitride 5 tungsten 6 tungsten plug 7 p-type silicon substrate 8 n-well 9 first p-well 10 second p-well 11 n ⁺ -type isolation region 12 STI 13 First interlayer insulating film 14 Second interlayer insulating film 15 Third interlayer insulating film 16 Protective film 17 Active region 18 Contact hole 19 Polysilicon gate electrode 20 Metal gate electrode 21 Bit line 22 Through hole 23 Al wiring

Continued on the front page (72) Inventor Yumiko Kono 650 Mitsuzawa, Hosaka-cho, Nirasaki, Yamanashi Prefecture Inside Tokyo Electron Co., Ltd. Reference) 5F038 AC02 AC14 AV06 BH03 DF05 EZ17 5F083 AD24 AD48 JA06 JA14 JA40 NA01 PR21

Claims (22)

[Claims] 1. A method of manufacturing a semiconductor device comprising at least a capacitor portion having a capacitor insulating film and a storage node electrode in contact with the capacitor insulating film, wherein a nitride refractory metal film having a predetermined surface is used as the storage node electrode. A method of manufacturing a semiconductor device, comprising: forming a morphological shape; and forming the capacitor insulating film on the storage node electrode. 2. The method according to claim 1, wherein the nitrided refractory metal film as the storage node electrode is formed by a chemical vapor deposition method. 3. When forming a nitrided refractory metal film as a storage node electrode by a chemical vapor deposition method, a halogen-based refractory metal gas and an ammonia gas are used, and the ratio is 1/20 to 10 with respect to ammonia. A halogen-based high melting point metal gas and an ammonia gas are introduced into the reaction vessel so that the growth temperature is set within a range of 300 to 600 ° C., and the reaction pressure is set within a range of 0.01 to 5.0 Torr. 3. The method according to claim 2, wherein the setting is performed. 4. The halogen-based high melting point metal gas includes at least WF ₆ , MoCl ₅ , TaCl ₅ and TiCl
_4. The method according to claim 3, wherein the method is selected from the group consisting of: 5. The method according to claim 3, wherein the surface area of the nitrided refractory metal film having the morphology is approximately 1.2 to 2.5 times the surface area of the nitrided refractory metal film before forming the morphology. A method for manufacturing a semiconductor device. 6. The method according to claim 1, wherein the refractory metal nitride film as the storage node electrode is selected from at least one of tungsten nitride, molybdenum nitride, tantalum nitride, and titanium nitride. . 7. The method according to claim 1, wherein the refractory metal nitride film as the storage node electrode is formed directly on an interlayer insulating film. 8. The method according to claim 7, wherein the interlayer insulating film is a silicon oxide film. 9. The method according to claim 1, further comprising performing a heat treatment on the storage node electrode using a nitriding gas. 10. The method according to claim 9, wherein the heat treatment using the nitriding gas is performed to reduce the contact resistance of the storage node electrode. 11. The heat treatment using the nitriding gas is performed at 70
The method according to claim 9, wherein the method is performed at a temperature of 0 ° C. or less. 12. The method according to claim 9, wherein the nitriding gas is an ammonia gas. 13. The method for manufacturing a semiconductor device according to claim 1, further comprising performing a heat treatment for densifying the capacitance insulating film. 14. The method according to claim 13, wherein the heat treatment for densifying the capacitor insulating film is performed to improve a leakage current characteristic. 15. The method according to claim 1, further comprising forming a plate electrode on the capacitance insulating film. 16. The method according to claim 1, wherein the capacitance insulating film is an insulating film having a high dielectric constant. 17. The method according to claim 1, wherein the capacitive insulating film is formed by a chemical vapor deposition method. 18. The method according to claim 16, wherein the capacitance insulating film is made of tantalum oxide. 19. The method according to claim 16, wherein the capacitance insulating film is made of perovskite titanate. 20. The perovskite titanate,
20. The method according to claim 19, wherein the method is barium titanate or strontium titanate. 21. A semiconductor device comprising at least a capacitor portion having a capacitor insulating film and a storage node electrode in contact with the capacitor insulating film, wherein the storage node electrode is made of a refractory nitrided metal material whose surface morphology can be controlled. A semiconductor device characterized by being used. 22. The semiconductor device according to claim 21, wherein the refractory metal nitride material is selected from at least one of tungsten nitride, molybdenum nitride, tantalum nitride, and titanium nitride.