JPH08153707A - Manufacturing method for semiconductor device - Google Patents

Abstract

PURPOSE: To remove contamination an electrode surface caused by dry-etching by, after selectively dry-etching an electrode containing ruthenium, etc., selecting such gas as oxygen gas and ozone gas, for treating the surface of a material with plasma. CONSTITUTION: On a silicon substrate 11, a silicon oxide film 12, TiN film 13, RuO2 film 14 and SOG film are formed, and further a fine resist pattern 16 is formed. Next, the SOG film 15 is dry-etched, then, after the RuO2 film 14 is etched with the SOG film 15 as a etching mask, the TiN film 13 is etched with the RuO2 film 14 as a etching mask. As a result, an anisotropic fine pattern is obtained, and at the same time, the fine pattern is covered with a contamination layer containing chlorine, fluorine and carbon. Then, with the substrate on which the fine pattern was previously formed, oxygen is introduced at specified pressure in a surface treatment device, oxygen plasma is generated by utilizing microwave discharge, and the contamination layer 17 is removed using it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a surface treatment of a noble metal after fine processing.

[0002]

_2. Description of the Related Art In recent years, typical conductive oxides having a rutile structure (RuO ₂ , IrO ₂ , OsO ₂ , RhO ₂ ) and platinum are used as capacitor electrode materials for microelectronic devices (for example, dynamic random access). Memory (DRAM) and Efram (FRAM))
R & D is making significant progress. In order to manufacture this microdevice, development of process technology such as film forming technology and fine processing technology of the conductive oxide and platinum is indispensable.

The present inventor has already proposed a technique of dry etching RuO ₂ among the conductive oxides. This technique will be described with reference to FIG. A silicon oxide film 2 is formed on a silicon substrate 1. Next, a titanium nitride film 3 is formed on the silicon oxide film 2 by a sputtering method.
To form a film. Further, a RuO ₂ film 4 is formed on the titanium nitride film 3 by using a reactive sputter rig method using oxygen gas.
To form a film. Next, a silicon oxide film 5 serving as an etching mask is formed, and a fine resist pattern 6 is formed by applying and developing a photosensitive resist on the silicon oxide film 5.
Is obtained (see FIG. 5 (a)).

First, ECR (Electron Cyc)
The silicon oxide film 5 is dry-etched using a plasma dry etching apparatus. The etching gas used is CHF ₃ (FIG. 5B). Then, using the etched silicon oxide film 5 as an etching mask, the RuO ₂ film 4 is formed.
Is a mixed gas of oxygen and chlorine (the maximum mixing ratio of chlorine is 75
% Effective) and etching is performed using the dry etching apparatus (see FIG. 5C). Subsequently, the unnecessary silicon oxide film 5 is removed by etchback using CHF ₃ gas (see FIG. 5D). Finally, using the etched RuO ₂ film 4 as an etching mask,
The fine pattern 7 is formed by etching the titanium nitride film 3 with chlorine gas (see FIG. 5E).

In the above technique, the surface of the fine pattern 7 is exposed to plasma after the step of etching back the silicon oxide film 5. As a result, the surface of the fine pattern 7 is contaminated with elements (carbon, halogen elements, etc.) in the etching gas.

FIG. 6 shows the result of observing the surface condition after the formation of the fine pattern 7 with a micro-Auger analyzer. It can be seen that the surface is contaminated with chlorine, fluorine and carbon. If an electronic device is formed in this contaminated state, the electrical characteristics of the device and its long-term reliability are likely to be significantly deteriorated.

That is, in order to obtain the electrical characteristics of the electronic device and its long-term reliability, the surface of the fine pattern 7 must be in a state equal to or extremely close to that at the time of forming the electrode material even after fine processing by dry etching. is there.

[0008]

In the conventional method of manufacturing a semiconductor device, the surface of the electrode material is contaminated by carbon and halogen elements in the process of forming a fine pattern of platinum or a conductive oxide by dry etching. This contamination seriously affects the electrical properties of electronic devices and their long-term reliability.

The present invention provides a method for manufacturing a semiconductor device including a surface treatment method which removes this contamination and brings the surface condition of the electrode to be equal to or extremely close to that at the time of forming the electrode material. is there.

[0010]

In order to achieve the above-mentioned object, the present invention provides a method for manufacturing a semiconductor device containing platinum or a conductive oxide, and in particular, fine etching by dry etching using a gas containing carbon or a halogen element. After the pattern formation, in order to remove the contamination of the electrode surface caused by dry etching, oxygen gas, ozone gas, steam gas,
It is characterized by including a step of treating at least one kind of gas among nitrogen oxide gas and treating the surface of the material with plasma.

[0011]

The principle of the present invention will be described. At the time of fine processing of the electrode by dry etching, a contamination layer is formed on the surface of the electrode. This contaminated layer is mainly composed of elements that constitute the halogen gas and fluorocarbon gas used for dry etching. Activated oxygen atoms and molecules generated by the plasma discharge chemically react with the contaminated layer. The expected chemical reaction formula is as follows.

O + C → CO (1) O + F → OF (2) O + X → OF (3) In the formula (3), X represents a halogen element other than fluorine. According to the above formula, the fluorocarbon reacts with the active oxygen atom to become carbon monoxide or oxygen fluoride and is removed. Also,
Other halogen elements become oxidized halides having a high saturated vapor pressure and can be easily removed.

[0013]

EXAMPLES Examples of the present invention will be described below. FIG.
FIG. 3 is a process sectional view showing an embodiment of the present invention.

The silicon substrate 11 is thermally oxidized to form a silicon oxide film 12 having a film thickness of 400 nm. Next, a TiN film 13 having a film thickness of 50 nm is formed on the silicon oxide film 12 by a DC magnetron sputtering method. Further, a RuO ₂ film 14 having a film thickness of 500 nm is formed on the TiN film 13 by using a reactive DC magnetron sputtering method using oxygen gas. Next, SOG (Spin o
(n glass) film 15 is applied to form a film having a thickness of 320 nm, and a fine resist pattern 16 is obtained by applying a photosensitive resist on the SOG film 15 and exposing and developing it with an optical lithography apparatus (see FIG. )reference).

Next, the SOG film 15 is dry-etched by an ECR plasma dry etching apparatus. The dry etching conditions used were etching gas CHF ₃ for 20 s.
The flow rate was set to ccm and the pressure was kept at 10 mTorr. Microwave power of 2.45 GHz is applied at 760 W for plasma generation, and in order to control the in-on kinetic energy in the plasma with respect to the substrate to be etched to a desired value, 2 M is applied to the lower electrode supporting the substrate to be etched.
15 W of high frequency power of Hz was applied. The etching time was 66 seconds (see FIG. 1 (b)). Subsequently, the RuO ₂ film 14 is etched with a mixed gas of oxygen and chlorine using the etched SOG film 15 as an etching mask. At that time, the etching condition is a gas layer flow rate of 200.
sccm, chlorine mixing rate 10%, pressure 15 mTorr, microwave 220 W, high frequency 150 W, etching time 2
It is 08 seconds (see FIG. 1 (c)). After etching the RuO ₂ film 14, the unnecessary SOG film 15 is removed by CHF.
_{It is} removed by an etch-back method using ₃ gases. The etch back conditions were the same as the SOG film etching conditions described above (see FIG. 1D). Then, using the RuO ₂ film 14 formed in the fine pattern as an etching mask, Ti
The N film 13 is etched with chlorine gas. Etching conditions are: chlorine gas flow rate 100 sccm, pressure 15 mTorr
r, the microwave electrode 220W, and the high frequency power 50W. As a result, an anisotropic fine pattern as shown in FIG. 1 (e) is obtained, and at the same time, the fine pattern surface has chlorine,
It was covered with a contamination layer 17 containing fluorine and carbon.

Next, for the purpose of removing the contaminated layer 17, the substrate on which the fine pattern was already formed was transferred from the ECR etching apparatus to the surface processing apparatus without being exposed to the atmosphere. The surface treatment device is several Tor
1. Introduce oxygen gas under a pressure of several tens to several Torr, and 2.
Oxygen plasma can be generated by utilizing microwave discharge using a microwave of 45 GHz. Further, by providing a metal grid between the plasma generation region and the substrate and electrically grounding the metal grid, it is possible to prevent charged particles from flowing into the substrate and only activated oxygen atoms and molecules can contribute to the surface treatment. It has a structure like this. Such plasma is generally called a downstream plasma. The surface treatment conditions are oxygen gas flow rate of 400
sccm, pressure 3 Torr, microwave 660W,
The substrate heating temperature was 150 ° C. and the surface treatment time was 180 seconds. Thus, a pattern with the contaminated layer removed is obtained (FIG. 1 (f)).

FIG. 2 shows the result of observing the surface of the fine pattern after the surface treatment using a micro Auger analyzer. The contaminated layer is completely removed,
The surface condition is close to that at the time of forming the RuO ₂ film, that is, R
The composition ratio of u and O is approximately 1: 2.

In the steam embodiment, the example in which the downstream plasma is used as the surface treatment apparatus has been extended, but the present invention is not limited to the capacitive coupling type plasma apparatus, the inductive coupling type plasma apparatus, and the ECR plasma as the surface treatment apparatus. apparatus,
It is also effective to use a helicon wave plasma device or the like. Also, it is effective to use ozone gas, water vapor, nitrogen oxide gas, or the like instead of oxygen gas. Further, although the example of RuO ₂ as the material to be etched has been extended, the present invention includes ruthenium, iridium and its oxide, osmium and its oxide, rhodium and its oxide, and platinum as the material to be etched, and an allogen element. It is also effective for surface treatment after dry etching with plasma using gas. That is, the configuration of each steam embodiment is merely an example, and the semiconductor device manufacturing method of the present invention includes a semiconductor device manufacturing method in which various modifications and changes are made to the configuration of the steam embodiment.

FIG. 3 shows a thin film capacitor obtained by the method of the present invention. 101 is n having a resistivity of 0.01 Ωcm
Type silicon substrate, 102 is a silicon oxide film (500 nm) of an interlayer insulating film, 103 is polysilicon doped with phosphorus as a conductor layer, 104 is RuO ₂ (500 nm) / TiN (50 nm) as a barrier metal, 10
5 is SrTiO ₃ (100 nm) as a dielectric film, 1
06 is Al (1 μm) / TiN (50 n as a conductor)
m). The silicon substrate 101 is thermally oxidized to form a silicon oxide film 102, a contact is opened at a desired position, polysilicon 104 is formed to a thickness of 1 μm by a CVD method, phosphorus is diffused, and etching is performed by plasma using chlorine gas. I went back and buried the contact.

After that, RuO ₂ was used as a barrier metal.
/ TiN105 was formed into a film by the DC magnetron sputtering method, processed into a desired size by the mixed gas plasma of chlorine and oxygen expanded in the example of FIG. 1, and then surface-treated with oxygen plasma. Subsequently, SrTiO ₃ 105 having a film thickness of 100 nm is formed at a substrate temperature of 450 ° C. by a CVD method, and then Al / T is formed by a DC magnetron sputtering method.
A film of iN106 was formed and processed into a desired size using CL ₂ gas plasma.

FIG. 4 is a diagram comparing the current-voltage characteristics of the surface-treated capacitor of the present invention and the conventional capacitor not subjected to any treatment. The conventional capacitor has a large leak current value in a low electric field. This is considered to be caused by a contaminated layer such as chlorine, fluorine and carbon.

On the other hand, it has been found that the thin film capacitor of the present invention has a small leakage current characteristic and is superior in long-term reliability to the conventional capacitor.

In the above embodiment, SrTiO3 is used as the high dielectric constant film. In the present invention, the chemical formula of the high dielectric constant film is represented by ABO ₃ , and A is B
at least one of a, Sr, Pb, La, Li and K, and B as Zr, Ti, Ta, Nb, Mg, Mn,
Fe, Zn, those comprising at least one or more of W, for example, (Ba, Sr) TiO3, PbTiO 3,
Pb (Zr, Ti) O ₃ , (Pb, La) (Zr, T
i) O ₃ , Pb (Mg, Nb) O ₃ , Pb (Mg, W)
O ₃ , Pb (Zn, Nb) O ₃ , LiTaO ₃ , LiN
bO ₃ , KTaO ₃ , KHbO _3, etc., or other chemical formulas such as Ta ₂ O ₅ , Bi ₄ Ti ₃ O ₁₂ , BaM
It is also effective to use gF ₄ or the like. The example of RuO2 / TiN as the barrier metal has been extended.
It is also effective to use a barrier layer such as Ti, Ta, TaN, ZrN or a laminated structure thereof instead of N. The present invention is also effective in a structure using ruthenium, iridium and its oxide, osmium and its oxide, rhodium and its oxide, and platinum instead of RuO ₂ . Furthermore, in the above-mentioned embodiment, the example in which the downstream plasma is used as the surface treatment apparatus has been extended. However, the present invention provides a capacitively coupled plasma apparatus, an inductively coupled plasma apparatus, an ECR plasma apparatus as the surface treatment apparatus,
It is also effective to use a helicon wave plasma device or the like. In addition, it is effective to use ozone gas, water vapor, nitrogen oxide gas or the like instead of oxygen gas. That is, the configurations of the above-described embodiments are merely examples, and the semiconductor device manufacturing method of the present invention includes a semiconductor device manufacturing method in which various modifications and changes are added to the configurations of the above-described embodiments.

[0024]

As described above, according to the present invention, the contamination of carbon and halogen elements on the surface of the electrode material caused by the fine pattern formation of platinum or the conductive oxide by dry etching is contaminated with this contamination. It is possible to provide a method for manufacturing a semiconductor device in which the electrode surface state is made closer to the state at the time of film formation of the electrode material, and the electrical characteristics of the electronic device and its long-term reliability are not impaired.

[Brief description of drawings]

FIG. 1 is a process sectional view showing an embodiment of the present invention.

FIG. 2 is a composition diagram of an electrode material surface obtained by a micro-Auger analyzer having a pattern obtained by the method of FIG.

3 is a cross-sectional view of a thin film capacitor formed using the method of FIG.

4 is a voltage of the capacitor of FIG. 3 and a conventional capacitor-
Current characteristic diagram.

FIG. 5 is a process sectional view of a conventional example.

6 is a composition diagram obtained by the micro-Auger analyzer having the pattern of FIG.

[Explanation of symbols]

1, 11, 101 Silicon substrate 2, 5, 12, 102 Silicon oxide film 3,13 TiN film 4,14 RuO ₂ film 15 SOG film 6,16 Fine resist pattern 7 Fine pattern 17 Contaminated layer 103 Phosphorus-doped polysilicon 104 Barrier metal RuO ₂ / TiN 105 SrTiO ₃ film 106 Al / TiON film

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication location H01L 27/10 451 27/108 21/8242 H01L 27/04 C 7735-4M 27/10 651

Claims (8)

[Claims] 1. A step of selectively dry etching an electrode containing at least one or more of ruthenium and ruthenium oxide, followed by at least one or more gas of oxygen gas, ozone gas, water vapor gas and nitride gas. And a step of treating the surface of the electrode. 2. A step of selectively dry etching an electrode containing at least one or more of iridium and iridium oxide, followed by at least one or more of oxygen gas, ozone gas, water vapor gas, and nitrogen oxide gas. A step of treating the surface of the electrode with a gas, the method for manufacturing a semiconductor device. 3. A step of selectively dry-etching an electrode containing at least one or more of osmium and osmium oxide, followed by at least one or more of oxygen gas, ozone gas, water vapor gas, and nitrogen oxide gas. And a step of treating the surface of the electrode with the gas described above. 4. A step of selectively dry etching an electrode containing at least one or more of rhodium and rhodium oxide, followed by at least one or more of oxygen gas, ozone gas, water vapor gas and nitrogen oxide gas. A step of treating the surface of the electrode with a gas, the method for manufacturing a semiconductor device. 5. A step of selectively dry etching an electrode containing platinum, followed by treating the surface of the electrode with at least one gas selected from oxygen gas, ozone gas, water vapor gas and nitrogen oxide gas. A method of manufacturing a semiconductor device, comprising: 6. A method of manufacturing a semiconductor device, wherein plasma is used in the surface treatment method according to claim 1, 2, 3, 4 or 5. 7. A method of manufacturing a semiconductor device, which comprises treating the surface of the remaining electrode with a gas containing neither carbon nor halogen element. 8. A method of manufacturing a semiconductor device having a capacitor element using a high dielectric constant film, wherein at least once or more immediately before forming the high dielectric constant film on the lower electrode of the capacitor element. A method for manufacturing a semiconductor device, comprising exposing the surface of a lower electrode to plasma using a gas containing oxygen atoms and not containing carbon and halogen elements, and subsequently growing the high dielectric constant film.