JP3082840B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the method of manufacturing a semiconductor device, TiCl ₄ and NH electrodes of a capacitor
₃ related to the formation using CVD-TiN.

[0002]

2. Description of the Related Art With miniaturization and high integration of devices,
The design size in the horizontal direction of the device is reduced. However, when the size of the capacitor is reduced, the accumulated charge capacity Q becomes Q = ε ₀ · ε · s / t (ε ₀ : vacuum permittivity, ε: permittivity, t: distance between electrodes, s: electrode area). As shown, the capacity decreases as the area decreases. For this reason, in order to secure the capacity required for the operation of the device, a three-dimensional structure is used instead of a conventional two-dimensional structure called a plate type to increase the surface area and secure the capacity. However, as the size of the device further increases, it becomes difficult to secure the capacitance only by increasing the surface area, and the complexity of the structure adversely affects the subsequent flattening of the interlayer film and the like. So, as an alternative solution,
In recent years, a technique for forming a capacitor using a ferroelectric material having a higher dielectric constant than a nitride film used as a conventional dielectric material has been studied.

[0003] Representative examples of the ferroelectric material, as shown in FIG. 3, can be mentioned capacitor formation technique using Ta ₂ O ₅ 5. Interlayer insulating film 2 on silicon substrate 1
After forming a resist pattern by lithography, a capacitor contact hole 3 is formed on the diffusion layer region by dry etching. After resist stripping, CVD
A polysilicon 4 doped with phosphorus is formed by a method, and a contact plug and a lower electrode are formed by lithography and dry etching. In this case, TiN6 is used as the upper electrode material. Conventionally, a reactive sputtering method has been widely used as the TiN film forming method. However, the sputtering method has poor step coverage, and has a problem that a shadow shadow effect occurs in a portion shadowed by sputtered particles, making it impossible to form TiN. Therefore, as a TiN film formation method instead of the sputtering method, a TiN film formation by a CVD method which has excellent coverage and is capable of forming a film over the entire surface is being studied.

[0004]

As a typical TiN film forming method by CVD, an LPCVD method using TiCl ₄ and NH ₃ has been widely studied. A comparison between the sputtering method and the LPCVD method shows that, for example, when these techniques are used to form the barrier metal of the contact, even if the contact has an aspect ratio of 5, the LPCVD method is used.
% Coverage can be obtained. On the other hand, the sputtering method can provide only a coverage of 10% or less. Further, in the LPCVD method, since the film formation proceeds at a rate determined by the surface reaction, the entire surface can be formed regardless of the pattern shape.

However, when TiN formed by using TiCl ₄ and NH ₃ is used for an upper electrode of Ta ₂ O ₅ ,
The reaction of Ta ₂ O ₅ with the Cl remaining in the N film and the TiN film itself causes a problem that the characteristics are deteriorated such as a decrease in capacity and a decrease in withstand voltage. Regarding this issue, Myung-Bum Lee, Hyeon
-Deep Lee, Byung-Lyul Par
k, U-In Chung, Young-Bum Ko
h and Moon-Yong Lee, Inter
national Electron Devices
MeetingTechnical Digest
1996, IEEE, pp. 683-686.

In order to solve the above-mentioned problem, Ta ₂ O
It is important to prevent the reaction at the interface between ₅ and TiN. However, comparing the binding energies of Ti and O, Cl or N, Ti-O> Ti-Cl ≧ Ti-N, and Ti is most easily bonded to O. Therefore, T
Oxidation is particularly likely to occur at the outermost surface where the iN bond is broken, and the reaction easily occurs at the interface with the oxide Ta ₂ O ₅ .

An object of the present invention is to provide a method of manufacturing a semiconductor device, in which TiN is deposited by CVD using TiCl ₄ and NH ₃ as an electrode material of a capacitor using Ta ₂ O ₅ as a dielectric. Ta ₂ O ₅
To provide a film forming method which prevents a reaction at an interface between TiN and TiN and has excellent step coverage.

[0008]

The present invention employs the following means to solve the above-mentioned problems.

(1) The electrode material of a capacitor using a dielectric containing O as a constituent element is made of TiCl
_4, a TiON film formed by a CVD method using NH ₃ and a gas containing O as a constituent element, and a TiN film formed by a CVD method using TiCl ₄ and NH ₃ as source gases, A method for manufacturing a semiconductor device used as a structure.

(2) Ta ₂ O is used as the material of the dielectric.
_{5. The} method for manufacturing a semiconductor device according to (1), wherein

(3) The method of manufacturing a semiconductor device according to (1), wherein H ₂ O, O ₂ or N ₂ O is used as the gas containing O as the constituent element.

(4) In the method of manufacturing a semiconductor device according to (1), a TiO ₂ film formed by a reaction between TiCl ₄ and a gas containing O as a constituent element is formed instead of the TiO film. A method for manufacturing a semiconductor device.

[0013]

[0014]

[0015]

When TiCl ₄ reacts with NH ₃ , the reaction equation is as shown in equation 1, and usually requires a film forming temperature of 600 ° C. or higher. On the other hand, TiCl ₄ and H ₂ O easily react at room temperature, and TiO 2
₂ and HCl are formed. Therefore, a TiON film can be easily formed by adding a very small amount of H ₂ O during TiN film formation. By thus forming the TiON film containing advance O at the interface of Ta ₂ O ₅ and TiN, it can prevent the Ta ₂ O ₅ film and the TiN film, Ta ₂
The reduction of the O ₅ film can be suppressed. Further, by adding H ₂ O, the decomposition reaction of TiCl ₄ proceeds, so that the residual Cl concentration in the TiON film becomes smaller than that of a normal TiN film, and the influence of the residual Cl can be suppressed.

6TiCl ₄ + 8NH ₃ → 6TiN + 24HCl + N ₂ (Formula 1) TiCl ₄ + 2H ₂ O → TiO ₂ + 4HCl (Formula 2)

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described in detail in Examples.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below. First, as shown in FIG. 1A, an interlayer insulating film 2 is deposited to a thickness of 1.0 μm on a silicon substrate 1, a resist pattern is formed by lithography, and a capacitor having a diameter of 0.3 μm is formed on a diffusion layer region by dry etching. Contact hole 3
To form After the resist is stripped, a polysilicon 4 doped with phosphorus is formed by a CVD method, and a contact plug and a lower electrode are formed by lithography and dry etching. Next, as shown in FIG. 1 (b), 30nm deposited Ta ₂ O _{5 5.} Thereafter, a TiN8 / TiON7 laminated film is formed. The TiN8 / TiON7 film forming method uses LPC
Continuous film formation was performed using a VD apparatus. First, a film forming temperature of 650 ° C., a film forming pressure of 20 Torr, and TiCl ₄ = 4
0 sccm, NH ₃ = 60 sccm, H ₂ O = 0.5 s
A 10 nm TiON film is formed under the condition of ccm. Next, in the same film forming chamber, TiCl ₄ = 40 sccm, NH ₃ = 60 sccm, and a TiN film is formed to a thickness of 40 nm at the same film forming temperature and pressure. Further, in this case, annealing was performed for 30 seconds in the same film forming chamber under the condition of NH ₃ = 3000 sccm to promote the elimination of Cl in the TiN film. Next, after a resist pattern was formed by lithography, TiN / TiON / Ta ₂ O ₅ was processed by dry etching to form a capacitor.

Next, a second embodiment of the present invention using TiN for the lower electrode will be described. As shown in FIG. 2, after opening the capacitor contact holes, for the contact resistance reduction, forming the TiSi ₂ 9 in the bottom of the capacitor contact holes by CVD. After that, TiON7 / TiN
8 is formed. In this case, first, TiN8 is added for 20 minutes.
A 0 nm film is formed, and a 10 nm film of TiON7 is formed thereon. The film forming method is the same as in the first embodiment. then,
The lower electrode of the capacitor is formed by lithography and dry etching. Further 30 Ta ₂ O ₅ 5 thereon
and a TiN8 / TiON7 film is formed again. The film forming method and the film thickness are the same as those in the first embodiment, and then, TiN / TiO
/ Ta ₂ O ₅ was etched.

Here, the derivative material containing O is Ta ₂ O ₅
However, as other dielectric materials, BaTiO ₃ , S
rTiO ₃ , PbZrTiO ₃ or SrBi ₂ Ta ₂ O
₉ or the like can also be used. Also here,
H ₂ O as a TiON film forming gas containing O as a constituent element
Was used, but O ₂ or N ₂ O may be used instead.

Further, instead of the TiON film, TiCl ₄
And a TiO ₂ film formed by a reaction between the gas and a gas containing O as a constituent element.

[0022]

According to the method of manufacturing a semiconductor device of the present invention, TiCl ₄ and NH _{3 are used} as an upper electrode of Ta ₂ O ₅ or the like.
When depositing TiN by the CVD method using, Ta ₂
Excellent TiN step coverage without reaction at the interface between the O ₅ or the like and TiN can be deposited.

[Brief description of the drawings]

FIGS. 1A and 1B are cross-sectional views illustrating a method for manufacturing a semiconductor device according to a first embodiment of the present invention, wherein FIG. 1A illustrates a first step and FIG.

FIG. 2 is a sectional view of a method for manufacturing a semiconductor device according to a second embodiment of the present invention.

FIG. 3 is a sectional view of a conventional method for manufacturing a semiconductor device.

[Explanation of symbols]

1 silicon substrate 2 insulating film layer 3 of polysilicon doped with contact hole 4 phosphate _{5 Ta 2 O 5 6 TiN 7} TiON 8 TiN 9 TiSi 2

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01L 27/04 H01L 21/822 H01L 27/108

Claims (4)

(57) [Claims] 1. An electrode material for a capacitor using a dielectric containing O as a constituent element includes TiCl as a raw material gas.
_4, a TiON film formed by a CVD method using NH ₃ and a gas containing O as a constituent element, and a TiN film formed by a CVD method using TiCl ₄ and NH ₃ as source gases, A method for manufacturing a semiconductor device, wherein the method is used as a structure. 2. The dielectric material of Ta ₂ O ₅
2. The method for manufacturing a semiconductor device according to claim 1, wherein: 3. The method according to claim 1, wherein H ₂ O, O _2, or N ₂ O is used as the gas containing O as the constituent element. 4. The method for manufacturing a semiconductor device according to claim 1, wherein Ti produced by a reaction between TiCl ₄ and a gas containing O as a constituent element is used instead of the TiON film.
A method for manufacturing a semiconductor device, comprising forming an O ₂ film.