JP2001284330A - Semiconductor device and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep the inner part of a vacuum container to be clean and to stably produce a semiconductor device by volatilizing unnecessary deposit on the inner wall of the vacuum container, which is caused after subjecting a ferroelectric/high dielectric thin film to CVD and a dry etching process, and discharging it outside the device. SOLUTION: A metal element, constituting the ferroelectric/high dielectric thin film which adheres to the inner wall of the vacuum container, is volatilized by making it into an organic metal complex by β-diketone. Oxide, halogenide and the like are reduced or hydrogenated by using reducing gas, such as H2. Then, they are volatilized, by making them into organic metal complexes by β-diketone.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an apparatus for manufacturing a semiconductor device using a high dielectric thin film and a ferroelectric thin film as a capacitor material, and a method for manufacturing a semiconductor device using the manufacturing apparatus.

[0002]

2. Description of the Related Art Conventional semiconductor devices include Si3N4 and Si3N4.
O2 is used as a capacitor material. With the miniaturization of wiring rules due to the high integration of semiconductor devices, the capacitor area has also been required to be reduced. The capacitance C of the capacitor can be expressed as C = ε0εS / d. Where ε
0 is the dielectric constant of vacuum, ε is the relative dielectric constant of the capacitor material, S
Is the electrode area, and d is the capacitor film thickness. Therefore, if the electrode area of the capacitor is simply reduced according to the miniaturization of the pattern rule, the capacitance is also reduced. If the capacitance is too small, the sensitivity of the sense amplifier is insufficient and the presence or absence of electric charge cannot be detected, or a soft error or the like may be caused. The theoretical minimum capacity to prevent errors is 2
It is said to be 5fF. As a measure for securing the capacitance, when a material having the same relative dielectric constant is used, the capacitor thickness d
Or increase the electrode area S.
However, there is a limit to reducing the film thickness due to the problem of leakage. Therefore, a structure that can increase the capacitor area without hindering the miniaturization of the pattern rule by adopting a three-dimensional structure called a trench type or a stack type has been adopted.

In this generation of electrode materials, polysilicon is used to prevent contamination and the like. If the trench type or the stack type alone becomes insufficient due to the high integration, a hemispherical polysilicon particle lump (HSG: Hal: Hal) is formed on the polysilicon electrode.
f Spherical Grain) to increase the electrode area.

When a semiconductor device is manufactured using polysilicon as an electrode and Si3N4 as a capacitor, the following method is used. That is, when an electrode film or a capacitor film is formed on a wafer, a chemical vacuum deposition method (CVD) is generally used because of good coverage at minute gaps and steps. A resist is applied on the obtained deposited film, and an etching pattern is exposed and developed to form a mask. Further, a capacitor is formed by performing dry etching using plasma. By the way, in CVD, a film is formed not only on a wafer but also on an inner wall of the apparatus. In addition, since etching proceeds by reacting the deposited film with the etchant to generate a volatile substance, a part of the reaction product is reattached to the inner wall of the apparatus and remains as an unnecessary deposited film. CVD
Undesired films generated by etching and etching increase the film thickness by repeatedly starting the wafer, generate stress due to a difference in thermal expansion coefficient from the base, etc., and peel off to cause foreign matter. In order to improve the yield, an unnecessary deposited film that causes foreign matters must be removed. Methods for removing the unnecessary deposited film include wet cleaning in which the apparatus is opened to the atmosphere and cleaning with a solvent or a chemical solution, and dry cleaning using gas or plasma without opening to the atmosphere. The wet cleaning has a drawback that the apparatus has to be opened to the atmosphere, so that the stopping time of the apparatus is prolonged. On the other hand, the dry cleaning is performed by decomposing an unnecessary deposited film on the inner wall of the apparatus by plasma or a reactive gas and discharging the decomposed film by a vacuum pump. Since it does not involve opening to the atmosphere, the apparatus can be cleaned in a much shorter time than wet cleaning. For example, a Si film as an electrode material is formed by CVD using SiH4,
Etching is performed with l2 or a Cl2 / O2 mixed gas. Unnecessary deposits in the Si film CVD apparatus are mainly Si, and are removed by gas cleaning using ClF3 or NF3. SiCl in etching equipment
x or SiOx is deposited and can be easily decomposed and removed by SF6 plasma. In addition, capacitor material Si3
The N4 film is a CV using a SiH2Cl2 / NH3 mixed gas.
D and etched by CF4 or CF4 / O2 mixed gas.

On the other hand, with the increase in the degree of integration of the semiconductor device, it is also necessary to increase the capacitance by forming a conventional three-dimensional structure such as Si3N4 as a capacitor film or by reducing the film thickness.
Limitations have come to light as the structure becomes more complex and the number of steps increases. Therefore, a capacitor using an insulator having a high relative dielectric constant ε has been studied. For example, T
PZT [(Pb, Zr) TiO2, which has been studied as a capacitor material of a nonvolatile memory due to the presence of a high dielectric substance such as a2O5 and polarization charge remaining even at an applied voltage of 0V.
3], BST [(Ba, Sr) TiO3], STO [S
Attention has been paid to ferroelectrics such as [rTiO3].

[0006] These high dielectrics and ferroelectrics are oxide films and require heat treatment for crystal growth, so that it is impossible to obtain a capacitance as designed.
This is because SiO2 is formed between the dielectric and the electrode due to the release of oxygen from the ferroelectric by the heat treatment and the bonding with Si. Therefore, a conductor that is not easily oxidized by heat treatment or a substance that is conductive even if oxidized is required for the electrode material. So platinum group Pt,
Ru, Ir, RuO2 and the like have been attracting attention as electrode materials.

By the way, a method of forming a capacitor using electrode materials such as a high dielectric material, a ferroelectric material, and a platinum group metal, which has been described above, is performed by CVD and etching because of good coverage. Is used for dry etching using plasma. However, as far as literatures published so far are concerned, the mainstream of dry etching is sputter etching or ion-assisted etching by accelerating Ar ions or the like with a high bias. This depends on the fact that the vapor pressure of chlorine compounds, fluorine compounds and the like is low and the boiling point is high (Table 1).

[0008]

[Table 1]

[0009] From this, the above-mentioned high dielectric or ferroelectric,
The electrode material has a large amount of redeposition of an etching reaction product, and a large amount of unnecessary deposits remains in the apparatus. Even when unnecessary deposits are removed by cleaning with gas or plasma, re-adhesion occurs and the cleaning speed is reduced. In addition, in the case of plasma cleaning, it is difficult to apply a high bias to the inner wall of the apparatus, so that an ion assist effect unlike dry etching cannot be expected. Therefore, the etch (cleaning) rate is slow, and it is difficult to perform the apparatus cleaning in a practical time. For this reason, in these apparatuses, at present, the apparatus is frequently opened to the atmosphere, and the generation of foreign substances is suppressed by performing wet cleaning in which unnecessary deposits are wiped with pure water or another chemical solution.

[0010]

As described above, high dielectric and ferroelectric materials and their electrode materials have low volatility of halogen-based etching reaction products and high boiling points, so that the inner wall of the apparatus is high. It is difficult to remove unnecessary deposits attached to the surface. An object of the present invention is to provide a method for removing unnecessary deposits on the inner wall of an apparatus in a short time.

[0011]

According to the present invention, unnecessary deposits on the inner wall of the apparatus are complexed and volatilized, and are discharged by a vacuum pump. This makes it possible to discharge unnecessary deposits more efficiently than in the case of discharging as conventional halides. When a ferroelectric substance is deposited by the CVD method, an unnecessary reaction may be required as an oxide, and an intermediate reaction such as reduction with H2 plasma may be required. In particular, since an etching product is present as a mixture of a halide, an oxide, or the like due to an etchant, it is necessary to generate a substance that easily forms a complex through an intermediate reaction.

[0012]

FIG. 1 shows an embodiment of apparatus cleaning in MOCVD of BST. Ba, Sr, Ti
The raw material gases described in JP-A-6-151383 and JP-A-8-1
39043, JP-A-9-219497 and the like,
Organometallic complexes complexed with β-diketones (eg, Ba (DPM) 2, Sr (DPM) 2, TiO (DM
P) 2) dissolved in a solvent such as tetrahydrofuran (THF). It is common practice to heat to about 150 to 300 ° C. and supply it by bubbling with Ar or the like as a carrier gas. Evacuation is performed by a vacuum pump, and the pressure is kept constant by adjusting the exhaust throttle and the gas flow rate. In the heating chamber 2 attached to the reaction vessel 1 in FIG. 1, Ba (DPM) 2, Sr (DPM) 2, TiO
Add (DMP) 2 in THF. The entire heating chamber 2 is uniformly heated so that the organometallic complex volatilized by the bubbler does not condense in the pipe. Ar as a carrier gas is introduced into each bubbler through a gas pipe 25. By controlling the flow rate of Ar supplied to each bubbler with a mass flow controller (not shown) installed in each of the 25 individual pipes, the flow rate of the source gas can be controlled. Volatilized organometallic complex is pipe 2
6 to the vacuum vessel 1. O2 is introduced into the vacuum vessel 1 previously drawn to a high vacuum in the pipe 27, the microwave power of 2.45 GHz is supplied through the waveguide 15, and the current is further passed through the coil 14 to 875.
A Gauss magnetic field is formed, and a low-pressure, high-density plasma is generated by electron cyclotron resonance (ECR).
The pressure for depositing is about 1 Pa. Since the film quality depends on the deposition temperature, the wafer 1 placed on the susceptor 13
Reference numeral 1 denotes that the temperature can be controlled to be constant by the heater 12. Wafer temperature at the time of deposition is 150 ~ 5
It is adjusted to about 00 ° C. With such a device configuration, B
When ST is deposited, Ba, Sr, Ti,
Although the composition ratio of O and the like are different, a compound containing these is generated as an unnecessary deposited film. The film thickness of the unnecessary deposition film increases with each process, and the film is peeled off due to a difference in thermal expansion coefficient between the unnecessary deposition film and the inner wall of the apparatus. In addition, by degassing from unnecessary deposits, Ba, Sr, T
The partial pressure of i, O, hydrocarbon radicals and the like changes, and the film quality of each wafer becomes unstable. Therefore, in order to prevent these problems, the apparatus is cleaned without opening the apparatus to the atmosphere at the timing of processing one wafer or processing one lot.

The β-diketone used for cleaning the apparatus or the compound which generates β-diketone by being decomposed by plasma is supplied by bubbling a heated liquid raw material with a carrier gas such as Ar. The films adhering to the inner wall of the apparatus in the BST thin film CVD process are Ba, S
An oxide film of r and Ti is a main component. So first, pipe 2
From step 9, H2 is supplied to the vacuum vessel to perform reduction by H2 plasma. Thereby, a single Ba, Sr, Ti or B
A hydride such as aH2, SrH2, TiHx is obtained. The vacuum vessel 1 may be provided with a temperature control means (not shown) to promote the reaction. By supplying a compound which is a kind of β-diketone, Ba and Sr are converted into β-diketone complex, volatilized, and exhausted by a vacuum pump. β-
The supply of the diketone is performed by supplying a carrier gas such as Ar supplied from the pipe 28 through the bubbler 24 and volatilizing it to the vacuum vessel 1 as in the case of the CVD. The reaction with the unnecessary deposition film when supplying β-diketone is performed without generating plasma. On the other hand, when supplying a compound that is decomposed by plasma to generate β-diketone, plasma is generated by microwaves to advance the reaction.

Here, the MOCVD apparatus is connected to an ECR-MOC
Although the VD apparatus was used, the CVD method is not limited to this. Therefore, the plasma generating means does not need to be of the ECR type using a microwave and a magnetic field. For example, a parallel plate type or an ICP type may be used.

Although H2 plasma is used as a reducing agent for cleaning, H2S, N2H2, hydrogen halide, hydrocarbon, etc. may be used as long as they generate reducing H radicals. . Ba, S
Since the purpose is to remove O atoms from the oxides of r and Ti, CO may be used.

FIG. 2 shows an embodiment of apparatus cleaning in a BST dry etching apparatus. BST etching is applied physics Vol. 63, No. 11, p1139-1142
Ar / Cl2, Ar / CF4, Ar / SF
6, mixed gas systems such as Ar / CF4 / O2 and Ar / HBr are being studied. The etching target is BiTiO3
However, as discussed in JP-A-6-151383, mixed gas systems of organic gases such as hydrocarbons and alcohols, halogens, and rare gases are also being studied. In any case, the reaction products after etching are Ba, Sr, T
It is a mixture of an oxide and a halide of i. Therefore, in dry cleaning of the etching apparatus, substantially the same method as in the case of the CVD apparatus can be applied.
Here, an ECR etching apparatus will be described as an example.
In this apparatus, etching is performed by supplying an etching gas to a vacuum vessel 1 which has been previously evacuated to a high vacuum by a vacuum pump.
Introduce more. Microwave power is introduced through the waveguide 34 and 875 Gau formed by the coil 35
An ECR plasma is generated by the ss magnetic field. The wafer 31 is placed on the wafer stage 33. The wafer stage also serves as an electrode for applying a bias 32 for attracting ions. As a result of performing etching in such a manner, unnecessary deposits adhering to the inner wall of the vacuum vessel 3 are cleaned as follows. That is, in the vacuum vessel 3 and the heater 4, the above-described reducing gas such as H 2 gas is introduced from a pipe 44 different from the etching gas supply system 36 to generate plasma, thereby generating an inner wall of the vacuum vessel 1. Reduce unnecessary deposits or obtain hydrides.
Thereafter, Ar, which is a carrier gas, is introduced from the bubbler 41 through the pipe 42 to the β-diketone or a compound that generates β-diketone by decomposition, and bubbling is performed to the pipe 43.
Through the vacuum vessel 3. The heater 4 is configured such that the organic gas volatilized by the bubbler does not condense in the pipe. The vacuum vessel 1 may be provided with a temperature control means for accelerating the reaction.

Here, as an example of the etching apparatus, ECR is used.
The explanation was made using the plasma method, but the parallel plate method, IC
The P system may be used.

[0018]

According to the present invention, the etching (cleaning) rate can be improved by using the present invention with respect to cleaning using a halogen-based gas or plasma cleaning conventionally used in an etching process.

[Brief description of the drawings]

FIG. 1 is a schematic view of an MOCVD apparatus for a BST thin film.

FIG. 2 is a schematic view of an apparatus for etching a BST thin film.

[Explanation of symbols]

 Reference Signs List 1 vacuum vessel 2 heater 11 wafer 12 wafer heating means 13 wafer stage 14 coil 15 waveguide 21 bubbler for Ba (TPM) 2 22 bubbler for Sr (TPM) 2 23 bubbler for TiO (TPM) 2 24 for β-diketone Bubbler 25 Carrier gas supply pipe 26 MOCVD raw material gas supply pipe 27 O2 supply pipe 28 Carrier gas supply pipe for β-diketone 29 Reduction gas supply pipe 3 Vacuum container 4 Heater 31 Wafer 32 Ion pull-in bias applying means 33 Wafer stage 34 Wave tube 35 Coil 36 Etching gas supply pipe 41 Bubbler for β-diketone 42 Carrier gas supply pipe for β-diketone 43 β-diketone supply pipe 44 Reduction gas supply pipe

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Miwako Suzuki 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture F-term in Hitachi, Ltd. Production Research Laboratory 5F004 AA15 BA14 BA20 BB11 BB18 BD04 DA01 DA04 DA17 DA18 DA23 DA24 DA26 DB00 EA34 5F045 AB31 BB08 DP03 DQ10 EB06 HA13 5F083 FR01 JA13 JA14 JA15 PR03 PR21

Claims (13)

[Claims] In a method of manufacturing a semiconductor device using a chemical vacuum deposition (CVD) device or a dry etching device, unnecessary deposits containing an alkaline earth metal adhered to an inner wall of the device are volatilized by complexing. A method for manufacturing a semiconductor device, comprising manufacturing a semiconductor device while keeping the inside of the semiconductor manufacturing device clean by discharging the semiconductor device outside the device by a vacuum pump. 2. In a method of manufacturing a semiconductor device using a chemical vacuum deposition (CVD) device or a dry etching device, unnecessary deposits containing an alkaline earth metal adhered to an inner wall of the device are easily bonded to a ligand. A method for manufacturing a semiconductor device, wherein a semiconductor device is manufactured by keeping the inside of a semiconductor manufacturing apparatus clean by discharging by a vacuum pump out of the apparatus by complexing via an intermediate product, thereby manufacturing the semiconductor device. 3. A method for manufacturing a semiconductor device using a chemical vacuum deposition (CVD) device or a dry etching device, wherein unnecessary deposits containing alkaline earth metals attached to the inner wall of the device are reduced using a reducing agent. Alternatively, a semiconductor device is manufactured by hydride formation using a hydride, volatilization by complexation, and discharge of the semiconductor manufacturing device by a vacuum pump to keep the inside of the semiconductor manufacturing device clean. Manufacturing method. 4. A method of manufacturing a semiconductor device using a chemical vacuum deposition (CVD) device or a dry etching device, wherein Ba, Sr, Ca, Zn, T adhered to an inner wall of the device.
The unnecessary deposition film containing at least one of a, Mg, Nb, Zr, Pb, and La is volatilized by complexing, and is discharged out of the device by a vacuum pump to keep the inside of the semiconductor manufacturing device clean. A method for manufacturing a semiconductor device, comprising manufacturing a semiconductor device. 5. A method for manufacturing a semiconductor device using a chemical vacuum deposition (CVD) device or a dry etching device, wherein Ba, Sr, Ca, Zn, T adhered to an inner wall of the device.
An unnecessary deposited film containing at least one of a, Mg, Nb, Zr, Pb, and La is volatilized by complexing via an intermediate product that is easily bonded to a ligand, and is discharged by a vacuum pump. A method for manufacturing a semiconductor device by keeping the inside of the semiconductor manufacturing apparatus clean. 6. A method of manufacturing a semiconductor device using a chemical vacuum deposition (CVD) device or a dry etching device, wherein Ba, Sr, Ca, Zn, T adhered to an inner wall of the device.
a, Mg, Nb, Zr, Pb, La unnecessary deposit film containing at least one or more of La, using a reducing agent, or hydride using a hydride, and then volatilized by complexation, A method for manufacturing a semiconductor device, comprising manufacturing a semiconductor device while keeping the inside of the semiconductor manufacturing apparatus clean by discharging the semiconductor device with a vacuum pump. 7. A method of manufacturing a semiconductor device using a chemical vacuum deposition (CVD) device or a dry etching device, wherein a platinum group (Ru, Rh, Pd, Od) adhered to an inner wall of the device.
s, Ir, Pt), volatilization by complexing an unnecessary deposited film containing at least one of Re and Au, and manufacturing the semiconductor device by keeping the inside of the semiconductor manufacturing apparatus clean by discharging by a vacuum pump. A method for manufacturing a semiconductor device, comprising: 8. A method for manufacturing a semiconductor device using a chemical vacuum deposition (CVD) device or a dry etching device, wherein a platinum group (Ru, Rh, Pd, Od) adhered to an inner wall of the device.
s, Ir, Pt), Re, and Au. Unnecessary deposited films containing at least one or more are volatilized by complexing via an intermediate product that easily binds to a ligand, and are volatilized. A method of manufacturing a semiconductor device, comprising manufacturing a semiconductor device while keeping the inside of the manufacturing apparatus clean. 9. A method of manufacturing a semiconductor device using a chemical vacuum deposition (CVD) device or a dry etching device, wherein a platinum group (Ru, Rh, Pd, Od) adhered to an inner wall of the device.
s, Ir, Pt), an unnecessary deposited film containing at least one of Re, and Au is reduced by using a reducing agent, or hydride is formed by using a hydride, and then volatilized by complexing. A method for manufacturing a semiconductor device, comprising: manufacturing a semiconductor device by discharging the semiconductor device while keeping the inside of the semiconductor manufacturing apparatus clean. 10. A semiconductor manufacturing apparatus comprising a gas supply / heating and exhaust system for realizing the semiconductor device manufacturing method according to any one of claims 1 to 9. 11. A ferroelectric thin film BST [(Ba, S
r) Unnecessary deposits after the end of the process in the CVD device or dry etching device of TiO3] are H2, H2
A cleaning method for a semiconductor manufacturing apparatus, wherein a volatile complex compound is generated by β-diketone after reducing or hydride using at least one or more reducing agents of S, N 2 H 2, hydrocarbon, and hydrogen halide. Method. 12. C of MTiO3 (M = Ba or Sr)
Unnecessary deposits after the process in the VD apparatus or dry etching apparatus are reduced or hydrided using at least one or more reducing agents of H2, H2S, N2H2, hydrocarbons, and hydrogen halides, and then β-diketone is used. A method for cleaning a semiconductor manufacturing apparatus, comprising generating a volatile complex compound. 13. A semiconductor manufacturing apparatus comprising a gas supply / heating and exhaust system for realizing the semiconductor manufacturing apparatus cleaning method according to claim 11. Description: