JPH0817162B2 - Method and apparatus for forming thin film of semiconductor device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for forming a thin film of a semiconductor device, and more particularly to a semiconductor substrate in a semiconductor device or an insulation formed on the semiconductor substrate. The present invention relates to a method and an apparatus for forming a thin film on a substrate such as a film by using a chemical vapor deposition (hereinafter referred to as CVD) method via an intermediate layer.

[Prior Art] Conventionally, a wiring pattern of a semiconductor device is usually
It is formed by using aluminum as a main raw material. However, when aluminum is used as the main raw material, protrusions called "hillocks" grow during the heat treatment after patterning, causing electrical short-circuiting of wiring and destruction of the interlayer insulating film. Furthermore, since the melting point of aluminum is as low as 600 ° C, heat treatment after wiring pattern formation is 450
It had to be suppressed to about ℃, which was a problem in production.

Therefore, recently, a refractory metal or a silicide of a refractory metal has been attracting attention as a wiring material replacing aluminum. Among these materials, tungsten (W, melting point: 3370 ℃, specific resistance (bulk): 5.6μΩ ・ c
m) is a high-melting point low-resistance material, which is being actively developed. As a method for forming such a W thin film, a CVD method excellent in step coverage (step coverage) has been attempted.

As a method of forming a tungsten thin film according to the CVD method, there is a method of reducing tungsten hexafluoride (WF ₆ ) with hydrogen (H ₂ ) or silane (SiH ₄ ). The reduction reaction formulas of this method are shown in the following formulas (1) and (2), respectively.

WF ₆ (g) + 3H ₂ (g) → W (s) + 6HF (g)… (1) 2WF ₆ (g) + 3SiH ₄ (g) → 2W (s) + 3SiF ₄ (g) + 6H ₂ (g)… ( 2) Here, (g) and (s) show the states of the gas phase and the solid phase, respectively. The method of reducing with H ₂ is superior in step coverage to the method of reducing with SiH ₄ . However, since H ₂ has a lower ability to reduce WF ₆ than SiH ₄ , the H ₂ reduction method has a lower deposition rate and lower nucleation power. Therefore, it is necessary to raise the deposition temperature in the H ₂ reduction method. However, increasing the deposition temperature causes an excessive increase in crystal grain size. Furthermore, the difficulty of nucleation causes deterioration of surface morphology and deterioration of in-plane film thickness uniformity. Therefore, W-CVD by the H ₂ reduction method of WF ₆ is usually difficult to realize as a production technique.

Further, the difficulty in W-CVD is adhesion. The W thin film formed by the CVD method has poor adhesion to the insulating film. Therefore, the intermediate layer is usually formed on the substrate or the insulating film, and the W thin film is formed on the intermediate layer. This intermediate layer plays a role of helping adhesion of the W thin film.
Such an intermediate layer, for example, polysilicon (Poly-Si) Si-based material such as tungsten silicide (WSI _X) a refractory metal silicide material such as, and a refractory metal such as titanium nitride (TiN) Nitride of.

However, when polysilicon is used, it is necessary to dope impurities corresponding to the bonding layer of each contact, the process is complicated, and the surface morphology of the deposited W thin film is not good.

The surface morphology of the W thin film is not good even when tungsten silicide is used.

Compared to these polysilicon and tungsten silicide, titanium nitride has an advantage that the W thin film deposited thereon has a good surface morphology and excellent adhesion. Further, since titanium nitride functions as a barrier metal capable of P-type and N-type bipolar contacts, it has excellent properties as a CVD-W underlay film.

[Problems to be Solved by the Invention] However, it was very difficult to form a tungsten film by the conventional CVD method by H ₂ reduction on such a TiN intermediate layer. In particular, there were problems in deposition rate, film thickness uniformity, surface morphology, and the like.

In Japanese Patent Application Laid-Open No. 63-250463, a mixed gas of WF ₆ and an inert gas or a mixed gas of WF ₆ gas and H ₂ gas is introduced, and W
A method of growing a metal thin film by depositing a thin film to a predetermined thickness, introducing a gas containing WF ₆ and a silane-based reducing gas, and reducing the WF ₆ gas with the silane-based reducing gas is disclosed. ing. Mixed gas of WF ₆ gas and inert gas or W
The W thin film initially formed by the introduction of the mixed gas of F ₆ gas and H ₂ gas has good contact characteristics with both N-type and P-type diffusion layers. Also, in the next step,
The tungsten film deposited by the WF ₆ gas and the silane-based reducing gas has a high deposition rate and can be thickened. Therefore, according to the method disclosed in this publication,
It is possible to realize a tungsten wiring having good contact characteristics for both N-type and P-type with no leakage current.

However, according to the method disclosed in this publication, even if the tungsten film is formed on the TiN intermediate layer, since the WF ₆ gas is reduced by the silane-based reducing gas, an excellent step such as the H ₂ reduction method is obtained. I can't get coverage.

An object of the present invention is to make it difficult to deposit a W film by the H ₂ reduction method.
An object of the present invention is to provide a thin film forming method and apparatus capable of forming a thin film having a high deposition rate, good film thickness uniformity, and good surface morphology even with an intermediate layer such as N.

Another object of the present invention is to provide a thin film forming method and apparatus capable of forming a metal thin film having a smooth surface with less surface roughness.

Still another object of the present invention is to provide a thin film forming apparatus that generates less dust during the thin film forming process.

[Means for Solving the Problems] A thin film forming method of the present invention is a method of forming a metal thin film on a middle layer formed on a substrate by a chemical vapor deposition method. , A step of activating the surface of the intermediate layer by introducing a metal halide gas constituting the thin film, and a step of activating a silane-based gas on the surface of the activated intermediate layer. A step of forming nuclei and a step of introducing a halide gas and a reducing gas onto the surface of the intermediate layer on which the nuclei are formed and depositing a metal thin film on the surface of the intermediate layer are provided.

In one preferred embodiment of the present invention, the metal thin film is a W thin film, the halide gas is WF ₆ gas, and the silane-based gas is SiH ₄ gas.

In this preferred embodiment, the intermediate layer is, for example,
It is a TiN layer.

The reducing gas used in the metal thin film deposition process is
H ₂ gas is preferred.

In the present invention, the base body on which the metal thin film is formed via the intermediate layer is a semiconductor substrate or an insulating film formed above the semiconductor substrate.

[Advantageous Effects of the Invention] According to the present invention, the silane-based gas is introduced onto the surface of the intermediate layer activated by the first step treatment to form nuclei on the surface of the intermediate layer. The nuclei promote the formation of nuclei of metal in the initial stage when forming a metal thin film by using the reduction method by the CVD method. Therefore, according to the method of the present invention, it is possible to obtain a metal thin film having a high deposition rate, good uniformity of film thickness, and good surface morphology.

The present invention is particularly useful in forming a tungsten thin film, but is not limited to forming a tungsten thin film. As shown in Table 1, the present invention can be applied to metals other than tungsten.

In the present invention, the intermediate layer is not limited to the TiN layer. Examples thereof include TiW, refractory metal or refractory metal silicide, and refractory nitride.
In particular, the advantage of the present invention becomes greater for intermediate layers that do not exhibit surface catalysis during metal thin film deposition.

The silane-based gas used to form nuclei is Si
In addition to H ₄ gas, silane-based gas such as disilane (Si ₂ H ₆ ) can be used.

In one preferred aspect (aspect) according to the present invention, the metal halide gas forming the thin film is
It is introduced with the metal surface of the metal forming the thin film arranged near the surface of the intermediate layer. In this aspect, the reason for disposing the metal surface in the vicinity of the surface of the intermediate layer is that the intermediate layer is activated in the first step and the disproportionation reaction (disproportionation reaction) between the metal surface and the halide gas is performed.
te reaction) is also used to contribute to nucleation. Taking the W thin film formation using WF ₆ as an example, the disproportionation reaction is as follows.

W + WF ₆ → 2WF ₃ ↑ The gas WF ₃ generated by the above disproportionation reaction diffuses on the surface of the intermediate layer and is adsorbed on the TiN layer which is the intermediate layer. Gas produced by the disproportionation reaction, The above WF _3, WF
A gas having a composition of _X (1 ≦ x ≦ 5, an integer) is generated, and TiN is similarly generated.
It is thought to be adsorbed on the layer.

During this first step, the WF ₆ gas also reacts directly with the TiN layer, which is the intermediate layer, to form substances that become precursors of nuclei, such as TiW, WN, and TiF _X , on the TiN layer. It is supposed to do.

The silane-based gas introduced in the next step reacts with WF _X adsorbed on the TiN layer as described above and TiW, which is a reaction product of TiN and WF ₆ , to produce Si-based gas such as WSi _Y. Precipitate nuclei. The reaction of WF ₆ and H ₂ in the next step proceeds due to the surface catalytic action of the nuclei thus deposited,
Thin film deposition proceeds.

In the present invention, nuclei exhibiting the surface catalytic action of W thin film deposition are carefully formed on the intermediate layer carefully before the initiation of the deposition reaction, so that the deposition rate is high and the film thickness can be made uniform. it can. Furthermore, a W thin film having a good surface morphology can be obtained. In particular, according to the aspect of arranging the metal surface above the surface of the intermediate layer, the WF _X produced by the disproportionation reaction, can be uniformly adsorbed on the intermediate layer, uniformly nuclei on the intermediate layer It can be deposited.

In the apparatus according to this aspect, a metal surface member arranged facing the surface of the intermediate layer is provided above the surface of the intermediate layer, and a surface member support base for supporting the metal surface member.

It is preferable that the surface member support base is provided with a heater for controlling the temperature of the metal surface member. By controlling the temperature of the metal surface member with the heater, the disproportionation reaction between the introduced halide gas and the metal of the metal surface member can be controlled.

It is preferable that the surface member support base is movably provided so that the distance between the surface of the intermediate layer and the metal surface member can be adjusted. By doing so, it becomes possible to more preferably control the diffusion path of the nuclear precursor to the substrate, which is generated as a result of the disproportionation reaction.

The metal surface member may be a substrate coated with a metal film, or may be a bulk metal plate. Further, this metal surface member preferably controls not only the circular shape but also the size and shape in order to more preferably control the diffusion path of the nuclear precursor to the substrate.

In the apparatus according to another aspect of the present invention, the pretreatment chamber for pretreating the surface of the intermediate layer and the pretreatment chamber for depositing the metal thin film on the surface of the pretreated intermediate layer are A separate deposition chamber is provided. According to this other aspect, the inner surface of the deposition chamber is formed of a material that does not surface catalyze the reaction for deposition of the metal thin film.

When the metal thin film is a W thin film, for example, quartz, SiC, or ceramic is used as such a material.

When the metal thin film is a W thin film, the pretreatment includes, for example, an activation treatment with WF ₆ gas and a nucleation treatment with SiH ₄ gas. In this case, the pretreatment chamber may have a pretreatment chamber for activation treatment and a pretreatment chamber for nucleation separately.

According to the apparatus of this other aspect, since the inner surface of the deposition chamber is formed of a material that does not show a surface catalytic action for the reaction for depositing the metal thin film, the nucleation transferred from the pretreatment chamber is performed. The metal thin film is not deposited on the inner surface of the deposition chamber other than on the completed substrate. Therefore, dust generation in the accumulated vertebra is prevented. Therefore, inside the deposition chamber. It is always kept clean and the yield can be improved.

Example FIG. 1A is a sectional view showing a state in which nuclei are formed on the intermediate layer according to the method of the present invention. Referring to FIG. 1A, Si-based nuclei 2 are formed on the TiN layer 1. This Si-based nucleus 2 is formed as follows. First, Ti
WF ₆ gas is introduced onto the N layer 1. This WF ₆ gas is TiN
It reacts with the surface of layer 1 to activate the surface of TiN layer 1.
Next, a silane-based gas is introduced onto the TiN layer 1, and the reaction product on the surface of the TiN layer 1 is reacted with the silane-based gas to form the Si-based nucleus 2.

FIG. 1B is a cross-sectional view showing an initial state when a metal thin film is deposited on the nucleated intermediate layer according to the method of the present invention. Referring to FIG. 1B, a W thin film 3 having a uniform thickness is deposited on the TiN layer 1. According to the present invention, since many Si-based nuclei 2 are formed on the TiN layer 1, the density of nuclei is high. Therefore, the W thin film 3 can be formed with a uniform thickness.

FIG. 1C is a cross-sectional view showing a state in which a metal thin film is deposited on the nucleated intermediate layer according to the method of the present invention. Referring to FIG. 1C, it is deposited on the TiN layer 1. The W thin film 3 is deposited with a uniform thickness. Therefore, the surface of the W thin film 3 is smoothed.

As described above, according to the present invention, the W thin film 3 formed on the TiN layer 1 can have a uniform thickness and its surface can be smoothed. Moreover, W is formed on the TiN layer 1.
Since many nuclei exist before the thin film deposition, the deposition rate can be increased.

FIG. 2A is a cross-sectional view showing an initial state when a metal thin film is formed on an intermediate layer without pretreatment according to a conventional method. Referring to FIG. 2A, a W nucleus 5 is formed on the TiN layer 4.
Are formed. In the conventional method, on the TiN layer 4,
Since there are no nuclei that show the surface catalytic action of the W thin film deposition reaction in advance, the nuclei in this case have to be deposited by the direct reaction between WF ₆ and H ₂ in the initial stage after the initiation of the deposition reaction.
As shown in FIG. 2A, W nuclei 5 of low density are formed and are nonuniformly deposited. The deposited W nuclei 5 serve as nuclei that exert a surface catalytic action on the subsequent reaction between WF ₆ and H ₂ , and a W thin film is deposited on the nuclei.

FIG. 2B is a sectional view showing a state in which a metal thin film is deposited on the intermediate layer without pretreatment according to the conventional method. Referring to FIG. 2B, a W thin film 6 having a non-uniform thickness is deposited on the TiN layer 4. As shown in FIG. 2A, the W nuclei 5, which are the nuclei for depositing the W thin film, are non-uniform and have low density.
Since it exists on the layer 4, the thickness of the W thin film 6 also becomes nonuniform. As a result, the surface of the W thin film 6 becomes rough.

FIG. 3 is a diagram showing the relationship between the film thickness of the metal thin film deposited according to the present invention and the deposition time. Referring to FIG. 3, the solid line shows the method according to the present invention, and the dotted line shows the method according to the conventional method. T ₃ , T ₂ and T ₁ respectively indicate the deposition temperature and have a relationship of T ₃ > T ₂ > T ₁ . The deposition temperature is in the range of 400-600 ° C. Referring to FIG. 3, according to the conventional method, there is a delay time, that is, an induction period, from when the gas of WF ₆ and H ₂ is introduced to when the deposition of the W thin film is actually started. There is. This is because the TiN layer surface is catalytically inactive, and WF ₆
It indicates that it takes time for the W nuclei that can be the catalyst resulting from the direct reaction of H ₂ to reach a certain density and size and to be catalytic. In contrast, according to the method of the present invention, there is no such induction period. The W thin film starts to be deposited immediately after the introduction of WF ₆ and H ₂ gas. This is because Si-based nuclei already exist on the surface of the TiN layer and the Si-based nuclei are active as a catalyst.

FIG. 4 is a schematic configuration diagram showing an apparatus used in one embodiment of the present invention. Referring to FIG. 4, reaction vessel
A substrate support 11 is provided inside the substrate 10. Substrate support
A substrate 14 is placed on top of 11. The substrate 14 is a substrate having a TiN layer on its surface as an intermediate layer. A W film 13 is formed on the surface of the substrate support 11. This W
The film 13 is a film formed as a result of the deposition of the W film on the surface of the substrate support 11 during the deposition of the W film on the substrate in the processes just before. Therefore, when a new substrate support is used, the W film does not exist on the surface thereof. However, the present inventors prefer that the W film is formed on the surface of the substrate support 11 for W film deposition. Is found. This suggests that the above disproportionation reaction contributes to the nucleation process. Therefore, the present inventors have previously formed a W film on the surface of the substrate support 11 before mounting the substrate when using a new substrate support. In this way, the substrate is placed on the substrate support on which the W film is formed and used.

A heater 12 for heating the substrate is provided in the substrate support 11.
Is provided. An inlet port 15 for introducing the raw material gas is provided on one side of the reaction vessel 10. Reaction vessel 10
An exhaust port 16 is provided on the other side. In the activation process by introducing WF ₆ gas (hereinafter referred to as “first step process”), the WF ₆ gas is introduced into the reaction vessel 10 through the inlet 15 together with the inert gas serving as the carrier gas. After the TiN layer surface of the substrate 14 is activated, it is exhausted from the exhaust port 16. Next, in the nucleation treatment with SiH ₄ gas (hereinafter referred to as “second step treatment”), SiH ₄ gas is used together with an inert gas as a carrier gas in the reaction vessel 10
Introduced into and nucleated on the surface of the TiN layer of substrate 14.
After that, the gas is exhausted from the exhaust port 16.

Next, WF ₆ gas and H ₂ gas are introduced into the reaction vessel 10 through the inlet 15 to deposit a W thin film on the TiN layer of the substrate 14. After the deposition, the gas in the reaction vessel 10 is exhausted from the exhaust port 16.

A W thin film was deposited using an apparatus as shown in FIG. Under the conditions of 450 ° C. and 0.2 Torr, WF ₆ gas was introduced at a gas flow rate of 300 SCCM and Ar gas as a carrier gas at a gas flow rate of 500 SCCM for 120 seconds to perform a first step treatment for activating the surface of the TiN layer.

Next, the introduction of WF ₆ gas was stopped, and the inside of the reaction vessel 10 was exhausted 1
The 6 was evacuated to remove the WF ₆ gas. At this time, SiH ₄ gas was introduced into the reaction vessel 10 at a gas flow rate of 100 SCCM and Ar gas at a gas flow rate of 500 SCCM for 120 seconds, and a second step treatment of forming a silicon-based nucleus on the surface of the activated TiN layer was performed.

Next, stop the introduction of SiH ₄ gas,
Hold at r and 450 ° C, introduce Ar gas at a gas flow rate of 100 SCCM, and add WF ₆ gas and H ₂ gas to 300 SCC each.
The gas was introduced for 300 seconds at a gas flow rate of M and 300 SCCM. A W thin film of about 4000Å was formed on the TiN layer by the H ₂ reduction method.

 The conditions for forming the above W thin film are summarized in Table 2.

The thickness of the obtained W thin film was measured by cross-sectional SEM observation. The measurement was performed near the center of the 6-inch substrate.

FIG. 5 is a diagram showing the relationship between the film thickness and the deposition time when a W thin film is deposited on the TiN layer. The TiN layer is a thermal oxide film (SiO ₂ ) 5000 Å formed on the Si substrate, or P
It is formed by depositing on a type Si substrate using a reactive sputtering method, and subsequently performing a heat treatment for 30 seconds in a nitrogen atmosphere at 800 ° C.

In FIG. 5, according to the conventional method, the W thin film is formed by directly supplying WF ₆ gas and H ₂ gas without performing the first step treatment and the second step treatment, and the first step treatment. The result of the comparative example is also shown by depositing a W thin film after performing only. The pretreatment and thin film forming conditions are as shown in Table 2.

FIG. 5 shows an example of the present invention, a conventional example, and a comparative example.
Expressed as As shown in FIG. 5, the conventional example and the comparative example have an induction period of about 7 minutes in which the W film is not deposited even if the WF ₆ gas and the H ₂ gas are introduced.
It is believed that this is the time it takes for the nuclei to be formed allowing for thin film deposition. Therefore, it is easily inferred from this example that TiN is a material in which W nuclei are hard to form. On the other hand, in the example of the present invention, the deposition of the W film is started immediately after the introduction of the WF ₆ gas and the H ₂ gas with almost no induction period. As a result, the film thickness 4000
It takes about 12 minutes in the conventional method to obtain the W film of Å under the conditions shown in Table 2, but it can be formed in about 5 minutes according to the present invention.

A sheet resistance map was measured after the W thin film deposition time of 5 minutes. FIG. 6 is a plan view showing a sheet resistance map of a thin film obtained according to the present invention. FIG. 7 is a plan view showing a sheet resistance map of a conventional thin film in which the first step process and the second step process are not performed. FIG. 8 is a diagram showing a sheet resistance map of a thin film when only the first step processing is performed. FIG. 9 is a plan view showing a sheet resistance map of a metal thin film of a comparative example subjected to only the second step treatment.

In FIG. 6 to FIG. 9, the lines show the contour lines of the resistance value. In the hatched portion in the central portion in FIGS. 7 to 9, substantially no W thin film is formed.

As shown in FIG. 6, the W thin film formed according to the present invention has a uniform film thickness over the entire 6-inch substrate. On the other hand, in the W thin films of the comparative example and the conventional example, the W thin film is formed in the peripheral portion, but the film is not deposited in the central portion. As the deposition time is increased, the deposition region progresses from the periphery to the center, but since the initial uniformity is reflected, it is impossible to form a uniform film with these conventional examples and comparative examples.

FIG. 10 shows an X-ray fluorescence analysis on the surface of the intermediate layer after the first step treatment in one embodiment according to the present invention.
It is a figure which shows the processing temperature dependence of Ti and W signal intensity. The first step treatment was carried out at various temperatures as shown in FIG. 10, the surface of the obtained intermediate layer was evaluated using fluorescent X-rays, and Ti and W signal intensities were measured. With reference to FIG. 10, in the temperature of 300 ° C. or lower, that is, in the formation temperature region of selective CVD-W, the strengths of Ti and W hardly change. However, in the temperature of 400 ° C. or higher, that is, in the blanket CVD-W formation temperature region which is a problem in the present invention, the strength of W rapidly increases. This indicates that TiN and WF ₆ are reacting during the first step treatment.

FIG. 11 shows the ESCA (Electron Spectroscopy for Chemical Ana) of the surface of the intermediate layer after the first step treatment and the second step treatment in one embodiment according to the present invention.
It is a figure which shows the analysis result by lysis). In Figure 11, a is shows the spectrum of the TiN layer surface after subjected to the first step process, b is the spectrum of the TiN layer surface by introducing a 120 seconds H ₂ gas after performing a first step treatment Shows. c shows the spectrum of the surface of the TiN layer which has been subjected to the second step treatment by introducing SiH ₄ gas for 120 seconds after the first step treatment according to the present invention. As can be seen from FIG. 11c, Si is formed on the surface of the TiN layer which has been subjected to the first step treatment and the second step treatment according to the present invention.
Is observed. On the other hand, no such Si peak is observed in the comparative samples a and b. It is apparent from a of FIGS. 10 and 11 that W is introduced into the surface of the TiN layer by the first step treatment. However, the effect of the present invention is not exerted only by performing the first step, as shown in FIG. Therefore, by the first step processing, Ti
It is not enough to introduce W on the N layer, and the first step treatment is followed by the second step treatment,
It is necessary that Si be introduced on the surface of the TiN layer. It is considered that the Si-based nuclei thus introduced promote nucleation in the initial stage of W thin film formation.
Then, according to the present invention, the W thin film can be deposited without the induction period. This is probably because the Si-based substance effectively acted on the nucleation for forming the W thin film.

As described above, according to this embodiment, before the W thin film is deposited, WF ₆ gas is first introduced to activate the TiN surface,
Subsequently, SiH ₄ gas is introduced to form Si-based nuclei on the TiN surface. Due to such Si-based nucleation, the induction period during the deposition of the W film is eliminated, and the uniformity of the film thickness is improved,
Further, a W thin film having a good surface morphology can be obtained.

According to the present invention, a good W thin film can be formed even on an intermediate layer such as a TIN layer that is difficult to undergo W-CVD.
The present inventors have further found that in the first step treatment of the present invention, not only the reaction between WF ₆ and TiN, but also the reaction between WF ₆ and W may be involved in nucleation. JR Creigh
ton's “Amechanism for Selectivity Loss during
Tungsten CVD "J.Electrochem.Soc., Vol.136, No.1, Ja
nuary 1989, P.271 describes a cause of loss of selectivity on an insulating film in a selective tungsten CVD system due to reduction of WF _{6 on} a substrate such as Si. According to this reference, W _X formed by the disproportionation reaction of W and WF ₆ formed in the contact hole
There occurs, this WF _X is to become the nucleus adsorbed on the insulating film, the selectivity of tungsten is described to decrease. The present inventors have found that such a disproportionation reaction between W and WF ₆ can be involved in the nucleation on the intermediate layer in the blanket W-CVD system targeted by the present invention. . According to a preferred aspect of the present invention, the halide gas is introduced in the state where the same metal surface as the metal deposited on the substrate is arranged near the surface of the intermediate layer.
The reason for disposing the metal surface in the vicinity of the surface of the intermediate layer is to utilize the disproportionation reaction occurring between the metal surface and the halide gas for nucleation on the substrate. The gas generated by such a disproportionation reaction is adsorbed on the surface of the intermediate layer and becomes a precursor of nuclei. In the method of the embodiment using the apparatus shown in FIG. 4, it is considered that the tungsten film 13 formed on the surface of the substrate support 11 is involved in such disproportionation reaction. The tungsten film 13 and the WF ₆ of the substrate support 11 surface causes a disproportionation reaction, and the resulting WF _X is adsorbed on the surface of the TiN layer on the substrate 14, the precursor of the nucleus or nuclear it is conceivable that. Therefore, the fourth
In the case of apparatus as shown in figure, WF _X gases produced by such disproportionation reaction is introduced from the periphery of the substrate 14.
As a result, WF _X gas is the nucleus adsorbed on part of the periphery of the substrate 14. With reference to FIG. 6-FIG. 9, in the case of using the apparatus shown in FIG. 4, the thickness of the W film becomes thicker around the substrate, the WF _X caused by such disproportionation reaction It is considered that the cause is adsorption. The present inventors
Adsorption of such WF _X is as uniformly performed on the surface of the intermediate layer, we have found that placing the metal surface member above the surface of the intermediate layer facing. Thus, increasing the flexibility of the supply direction of the intermediate layer surface of the different WF _X is a conventional device, the control is improved.

In an apparatus according to another aspect of the present invention, a pretreatment chamber for pretreating the surface of the intermediate layer and a deposition chamber for depositing a metal thin film are separately provided, and the inner surface of the deposition chamber is made of metal. It is made of a material that does not surface catalyze the reaction for thin film deposition.

FIG. 12 is a schematic configuration diagram showing an apparatus of an embodiment according to another aspect of the present invention. Referring to FIG. 12, the reaction vessel is composed of a WF ₆ pretreatment chamber 21, a SiH ₄ pretreatment chamber 22 and a W film deposition chamber 2
It is divided into 3 of 3. A substrate table 24 is provided in the WF ₆ pretreatment chamber 21. A substrate 25 is placed on the substrate table 24. A tungsten plate material serving as a metal surface member 30 is provided above the substrate 25, and this is supported by a surface member support base 31. Face member support 31
Is provided so that it can be moved up and down to improve controllability. A heater 32 is provided in the surface member support base 31.
The WF ₆ pretreatment chamber 21 is provided with an inlet 27 for introducing a mixed gas of WF ₆ gas and carrier gas. Also WF ₆
An exhaust port 28 for discharging the gas in the pretreatment chamber 21 to the outside is provided.

A SiH ₄ pretreatment chamber 22 is provided adjacent to the WF ₆ pretreatment chamber 21. A substrate stand 33 is provided in the SiH ₄ pretreatment chamber 22. A heater 34 for heating a substrate placed on the substrate table 33 is provided in the substrate table 33. The SiH ₄ pretreatment chamber 22 is provided with an inlet port 35 for introducing a mixed gas of SiH ₄ and a carrier gas. An exhaust port 36 is also provided in the SiH ₄ pretreatment chamber 22. WF ₆ pretreatment chamber 21 and S
A transfer door 37 is provided between the iH ₄ pretreatment chamber 22 and the iH ₄ pretreatment chamber 22.

A W film deposition chamber 23 is provided adjacent to the SiH ₄ pretreatment chamber 22. A substrate table 38 is provided in the W film deposition chamber 23. A heater 39 for heating a substrate placed thereon is provided in the substrate table 38. The W film deposition chamber 23 is provided with an inlet 40 for introducing WFS ₆ gas and H ₂ gas. Further, the W film deposition chamber 23 is provided with an exhaust port 41 for exhausting the gas in the chamber. SiH ₄ pretreatment room 22
A transfer door 42 is provided between the W film deposition chamber 23 and the W film deposition chamber 23. The inner surface of the W film deposition chamber 23 is formed of a material that does not exhibit a surface catalytic action on the reaction for depositing the W film. Examples of such materials include quartz and Si.
C, ceramic, or the like can be used.

A load lock mechanism 44 is provided in the WF ₆ pretreatment chamber 21. A load door 29 is provided between the load lock mechanism 44 and the WF ₆ pretreatment chamber 21. A load lock mechanism 45 is provided in the W film deposition chamber 23. Load lock mechanism
An unroat door 43 is provided between 45 and the W film deposition chamber 23.

Although the mechanism for transferring the substrate 15 is not shown in FIG. 12, a commonly used transfer mechanism can be used for these.

The substrate 25 in which the TiN layer is formed on the Si substrate as in the above-described embodiment is first put into the load lock mechanism 44 and set to predetermined conditions, and then the substrate in the WF ₆ pretreatment chamber 21 is passed through the load door 29. Place on table 24. The WF ₆ pretreatment chamber 21, WF ₆ gas is introduced together with the carrier gas from the inlet 27. The introduced WF ₆ gas reacts with the TiN layer of the substrate 25 to form a reaction product as described above on the surface. At the same time, the WF ₆ gas causes a disproportionation reaction with W of the metal surface member 30 provided above the substrate 25 to generate WF _X. This WF _X is a board
Adsorbed on the surface of 25 TiN layers. As a result, a substance serving as a precursor of nuclei is adsorbed on the surface of the TiN layer. The temperature of the substrate at this time can be adjusted by the heater 26. In addition to the temperature of the substrate 25, since the heater 32 is provided in the surface member support base 31 that supports the metal surface member 30, the temperature of the metal surface member 30 can be controlled by the heater 32. This makes it possible to control the disproportionation reaction. In the apparatus shown in FIG. 4, the reaction temperature of WF ₆ and TiN and the disproportionation reaction temperature of WF ₆ and W (those deposited on the substrate support) were the same in the first step, but in this Example Then, the optimum temperature for each reaction can be set independently. After the first step treatment, the gas in the chamber is exhausted from the exhaust port 28, and the next SiH ₄ pretreatment chamber 22 is passed through the transfer door 37 so that the substrate 25 after the first step treatment does not come into contact with the air.
Sent to

In the SiH ₄ pretreatment chamber 22, SiH ₄ gas is introduced together with the carrier gas through the inlet 35. This SiH ₄ gas causes the nuclear precursor on the TiN surface of the substrate 25 to become Si-based nuclei. After such a second step process, the gas in the chamber is exhausted to the outside through the exhaust port 36. The substrate thus nucleated passes through the transfer door 42 and is transferred to the next W film deposition chamber 23 without being exposed to air (to maintain the catalytic activity).

In the W film deposition chamber 23, WF ₆ gas and H ₂ gas are introduced through the inlet 40. As a result, the WF ₆ gas is reduced by the H ₂ gas, and the W film is deposited on the surface of the TiN intermediate layer of the substrate 25. Since Si-based nuclei have already been formed on the surface of the TiN layer, the H ₂ reduction of WF ₆ easily progresses, and the W film can be densely deposited, and can be deposited in a short time.
The inner surface of the W film deposition chamber 23 is made of quartz, SiC, ceramics or the like that does not exhibit a surface catalytic action in the W film formation reaction. Therefore, the W film that causes dust is not deposited on the inner surface of the W film deposition chamber 23, so that the W film deposition chamber 23 can always be kept clean.

The substrate after the W film is deposited is sent to the load lock mechanism 45 through the unload door 43.

In the apparatus of this embodiment, in the WF ₆ pretreatment chamber 21,
A metal surface member 30 for disproportionation reaction is provided above the substrate 25. The metal surface member 30 faces the surface of the TiN layer of the substrate 25.
Since is provided, WF _X produced by disproportionation reaction of the metal surface member 30 and the WF ₆ gas is uniformly adsorbed while being controlled on the TiN layer. Therefore, as in the case of using the apparatus shown in FIG. 4, no longer be only WF _X portion around is adsorbed. By uniformly WF _X on the surface of the TiN layer is adsorbed, becomes uniform distribution of the nuclear density in the substrate surface, also becomes uniform in the inner surface thickness of W film is deposited on this. As a result of the high nuclear density and even distribution,
The surface smoothness of the deposited W film is also good.

The inner surface of the W film deposition chamber 23 is made of a material having no surface catalytic action on the W film forming reaction. Therefore, the W film is not deposited on the inner surface of the reaction chamber, and if W is deposited on the inner surface, the dust generated by peeling off the W film can be significantly reduced. When the apparatus shown in FIG. 4 is used, a new W film is deposited on the inner surface of the reaction container 10, especially on the W film formed on the substrate support 11. The W film becomes thicker each time the W film is formed on the substrate. Therefore, as the number of times of forming the tungsten film is increased, W peels off from the wall surface and becomes W. In the apparatus of FIG. 4, the inside W of the reaction container plays an important role as described above, but at the same time it is also a dust generating source. Due to the generation of such dust, it is necessary to frequently clean the inside of the reaction container, resulting in a decrease in operating rate. In the apparatus as shown in FIG. 12, since the generation of such dust is prevented, cleaning of the inside of the container is unnecessary, and the operating rate can be increased.

The apparatus shown in FIG. 12 is a single-wafer type apparatus that processes substrates one by one, but the apparatus according to the present invention may be a batch processing type apparatus.

As a carrier gas for WF ₆ and SiH ₄ , an inert gas such as Ar, He and N ₂ can be used. In the apparatus shown in FIG. 12, the surface member support base 31 is provided with the heater 32 for controlling the temperature of the metal surface member 30. Therefore, only the metal surface member 30 can be independently temperature controlled. In the case of the device shown in FIG. 4, the tungsten film 13 is provided on the surface of the substrate support base 11.
If the temperature of the substrate 14 is also controlled, the temperature of the substrate 14 thereon may change at the same time.

According to another aspect of the present invention, since the metal surface member for disproportionation reaction is separately provided, the shape of the metal surface member is variously adjusted such as its size, distance from the substrate, and installation location. it can be, it is possible to control the distribution of adsorption of WF _X to the substrate plane.

Although the apparatus shown in FIG. 12 has a configuration in which it is divided into three rooms, it may be configured in two. For example, the WF ₆ pretreatment chamber and the SiH ₄ pretreatment chamber may be combined to form one pretreatment chamber. In this case, when the first step process is completed, all the gas in the chamber is exhausted, and then the second step process is performed. In this case, at the normal pretreatment temperature, thermal decomposition of SiH ₄ does not occur, so that no Si film is deposited on the metal surface member for the disproportionation reaction.

As another method, the SiH ₄ pretreatment chamber and the W film deposition chamber may be combined to form one chamber. In this case, in the WF ₆ pretreatment room,
After the first step processing is completed, the substrate is moved to the W film deposition chamber and first the second step processing is performed. In this case, the Si film is not deposited in the W film deposition chamber at the normal blanket W-CVD temperature. After exhausting all the gas in the room,
By introducing WF ₆ and H ₂ gas together with carrier gas,
Perform film deposition.

In the above description, only the method of reducing WF ₆ with H ₂ gas has been described, but the method and apparatus of the present invention are
It can also be applied to a blanket W-CVD method in which WF ₆ is reduced with SiH ₄ gas.

FIG. 13 is a sectional view showing an example of a semiconductor device to which the metal thin film formed according to the present invention is applied. Thirteenth
Referring to the figure, 50 is a Si substrate, 51, 52 and 53 are impurity diffusion layers, 55 and 56 are word lines, 54 is a field shield plate, 58 is a poly-Si storage node, and 59 is a poly-silicon storage node.
Si cell plate, 60 and 61 are interlayer insulating films, 62 is a plug, 63 is a TiN layer, 64 is a W plug obtained by etching CVD-W, 65 is a TiN layer, 66 is a W film, 67 is a W bit line 68 is an interlayer insulating film, and 69 is an Al wiring.

In such a DRAM memory cell, the W film formed by the method of the present invention is applied to the formation of the W plug 64 formed on the TiN layer 63 and the W film 66 formed on the TiN layer 65. can do.

[Various Aspects of the Invention] Various aspects of the present invention are described below.

(1) A thin film forming method for a semiconductor device, comprising forming a metal thin film on a middle layer formed on a substrate by a chemical vapor deposition method, the metal constituting the thin film on the surface of the middle layer. The step of activating the surface of the intermediate layer by introducing a halide gas, and forming a nucleus on the surface of the intermediate layer by introducing a silane-based gas on the surface of the activated intermediate layer. Forming a thin film of a semiconductor device, comprising: a step of introducing the halide gas and a reducing gas onto the surface of the intermediate layer on which the nuclei are formed, and depositing the metal thin film on the surface of the intermediate layer. Method.

(2) The metal thin film includes a W thin film, the halide gas includes WF ₆ , and the silane-based gas includes SiH ₄ .
The method of (1) above.

(3) The method according to (2) above, wherein the intermediate layer includes a TiN layer.

(4) The metal thin film deposition step uses H ₂ as a reducing gas.
The method according to (1) above, which comprises a step of using a gas.

(5) The metal thin film deposition step uses Si as a reducing gas.
The method according to (1) above, which comprises a step of using H ₄ gas.

(6) The method according to (1) above, wherein the base is a semiconductor substrate.

(7) The method according to (1) above, wherein the base is an insulating film formed above a semiconductor substrate.

(8) A method for forming a thin film of a semiconductor device, which comprises forming a metal thin film on a middle layer formed on a substrate by chemical vapor deposition, wherein the thin film is formed in the vicinity of the surface of the middle layer. In a state where a metal surface of the same kind as the metal is arranged, by introducing a metal halide gas that constitutes the thin film, a step of activating the surface of the intermediate layer, and on the surface of the activated intermediate layer. A step of forming a nucleus on the surface of the intermediate layer by introducing a silane-based gas, and introducing the halide gas and a reducing gas on the surface of the intermediate layer on which the nucleus has been formed, A step of depositing the metal thin film on a surface, the method for forming a thin film of a semiconductor device.

(9) The metal thin film includes a W thin film, the halide gas includes WF ₆ , and the silane-based gas includes SiH ₄ .
The method of (8) above.

(10) The method according to (9) above, wherein the intermediate layer includes a TiN layer.

(11) The metal thin film deposition step uses H ₂ as a reducing gas.
The method according to (8) above, which comprises a step of using a gas.

(12) The metal thin film deposition process uses Si as a reducing gas.
The method according to (8) above, which comprises using H ₄ gas.

(13) The method according to (8) above, wherein the base is a semiconductor substrate.

(14) The method according to (8) above, wherein the base is an insulating film formed above a semiconductor substrate.

(15) A device for carrying out the method of (8) above, which supports a metal surface member disposed above the surface of the intermediate layer so as to face the surface of the intermediate layer, and supports the metal surface member. Thin film forming apparatus for a semiconductor device, comprising:

(16) The device according to (15), wherein the surface member support base is provided with a heater for controlling the temperature of the metal surface member.

(17) The device according to (15), wherein the surface member support base is movably provided so that a distance between the surface member support base and the surface of the intermediate layer can be adjusted.

(18) The device according to (15), wherein the metal surface member is a metal coated with a metal film.

(19) The device according to (15) above, wherein the metal surface member is a bulk metal plate.

(20) An apparatus for forming a metal thin film on an intermediate layer formed on a substrate by a chemical vapor deposition method, comprising a pretreatment chamber for pretreating the surface of the intermediate layer, A deposition chamber provided separately from the pretreatment chamber for depositing the metal thin film on the surface of the pretreated intermediate layer, wherein an inner surface of the deposition chamber is for depositing the metal thin film. An apparatus for forming a thin film of a semiconductor device, which is formed of a material that does not exhibit a surface catalytic action on a reaction.

(21) The metal thin film includes a W thin film, and the pretreatment is WF.
The apparatus according to (20) above, including activation treatment with ₆ gas and nucleation treatment with SiH ₄ gas.

(22) The pretreatment chamber has a pretreatment chamber for activation treatment and a pretreatment chamber for nucleation separately.
1) Equipment.

(23) The material that does not exhibit the catalytic action is quartz, SiC,
The device according to (21) above, which is at least one material selected from the group consisting of: and ceramics.

[Brief description of drawings]

FIG. 1A is a sectional view showing a state in which nuclei are formed on the intermediate layer according to the method of the present invention. FIG. 1B is a cross-sectional view showing an initial state when a metal thin film is deposited on the nucleated intermediate layer according to the method of the present invention. FIG. 1C is a sectional view showing a state in which a metal thin film is deposited on the intermediate layer on which nuclei are formed according to the method of the present invention. FIG. 2A is a cross-sectional view showing an initial state when a metal thin film is formed on an intermediate layer without pretreatment according to a conventional method. FIG. 2B is a sectional view showing a state in which a metal thin film is deposited on the intermediate layer without pretreatment according to the conventional method. FIG. 3 is a diagram showing the relationship between the film thickness of the metal thin film deposited according to the present invention and the deposition time. FIG. 4 is a schematic configuration diagram showing an apparatus used in one embodiment of the present invention. FIG. 5 is a diagram showing the relationship between the film thickness of the metal thin film and the deposition time in one embodiment according to the present invention. FIG. 6 is a plan view showing a sheet resistance map of a metal thin film of one embodiment according to the present invention. FIG. 7 is a plan view showing a sheet resistance map of a metal thin film obtained by the conventional method. FIG. 8 is a plan view showing a sheet resistance map of a comparative metal thin film subjected to only the first step treatment. FIG. 9 is a plan view showing a sheet resistance map of a comparative metal thin film subjected only to the second step treatment. FIG. 10 is a diagram showing the processing temperature dependence of the Ti and W signal intensities on the surface of the intermediate layer after the first step processing in one example according to the present invention. FIG. 11 shows the ES of the intermediate layer surface after the first step treatment and the second step treatment in one embodiment according to the present invention.
It is a figure which shows the analysis result by CA. FIG. 12 is a schematic configuration diagram showing an apparatus of an embodiment according to another aspect of the present invention. FIG. 13 is a sectional view showing an example of a semiconductor device to which the metal thin film formed according to the present invention is applied. In the figure, 1 is a TiN layer, 2 is a Si-based nucleus, 3 is a W thin film, 10
Is a reaction vessel, 11 is a substrate support, 12 is a heater, 13 is a tungsten film, 14 is a substrate, 15 is an inlet, 16 is an outlet, and 21 is a WF.
₆ pretreatment chamber, 22 SiH ₄ pretreatment chamber, 23 W film deposition chamber, 24 substrate stage, 25 substrate, 26 heater, 30 metal surface member, 31 surface member support, 32 heater, 33 is a board stand, 34 is a heater,
38 is a substrate stand, 39 is a heater, 63 is a TiN layer, 64 is a W plug, 6
5 indicates a TiN layer, 66 indicates a W film, and 67 indicates a W bit line.

Continuation of front page (56) Reference JP-A-2-237116 (JP, A) JP-A-62-118525 (JP, A) JP-A-1-172572 (JP, A) JP-A-62-239526 (JP , A) JP 63-250446 (JP, A) JP 2-79446 (JP, A) JP 1-73717 (JP, A) JP 1-17866 (JP, A) JP 2-170424 (JP, A) JP-A-2-185023 (JP, A)

Claims (3)

[Claims] 1. A method for forming a thin film of a semiconductor device, comprising forming a metal thin film on a middle layer formed on a substrate by a chemical vapor deposition method, wherein the thin film is formed on the surface of the middle layer. A step of activating the surface of the intermediate layer by introducing a metal halide gas to form a nucleus on the surface of the intermediate layer by introducing a silane-based gas on the surface of the activated intermediate layer. A step of forming, and a step of introducing the halide gas and a reducing gas on the surface of the intermediate layer on which the nuclei are formed to deposit the metal thin film on the surface of the intermediate layer, Thin film forming method. 2. A method for manufacturing a thin film of a semiconductor device, comprising forming a metal thin film on a middle layer formed on a substrate by chemical vapor deposition, the thin film being formed above the surface of the middle layer. In the state where the metal surface of the constituent metal is arranged, by introducing a metal halide gas that constitutes the thin film, a step of activating the surface of the intermediate layer, and on the surface of the activated intermediate layer. A step of forming a nucleus on the surface of the intermediate layer by introducing a silane-based gas, and introducing the halide gas and a reducing gas on the surface of the intermediate layer on which the nucleus has been formed, A step of depositing the metal thin film on a surface, the method for forming a thin film of a semiconductor device. 3. An apparatus for forming a metal thin film on a middle layer formed on a substrate by a chemical vapor deposition method, which is a pretreatment chamber for pretreating the surface of the middle layer. And a deposition chamber that is provided separately from the pretreatment chamber for depositing the metal thin film on the surface of the pretreated intermediate layer, and the inner surface of the deposition chamber is for deposition of the metal thin film. Device for forming a thin film of a semiconductor device, which is formed of a material that does not exhibit surface catalysis for the reaction.