JP3154145B2 - CVD apparatus and film forming method using the apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a side wall heating type CVD apparatus and a film forming method using the apparatus, and more particularly to a side wall heating type decompression CVD apparatus used for forming a metal thin film such as tungsten in the manufacture of a semiconductor device. The present invention relates to a film forming method using an apparatus.

[0002]

2. Description of the Related Art The role of a film forming apparatus for forming a metal thin film or the like used in the manufacture of a semiconductor device has become particularly important in recent years with the high integration of semiconductor devices. The CVD (Chemical Vapor Deposit) method, in which a raw material is supplied as a gas and a thin film is deposited and formed by gas phase reaction or chemical reaction on the substrate surface
An ion (chemical vapor deposition) apparatus is an indispensable apparatus when manufacturing a semiconductor device such as ULSI. That CV
In the D apparatus, it is important that the source gas concentration on the substrate surface is uniform.
This greatly affects the distribution of the material uniformity or the film thickness uniformity of the VD film. Therefore, it is important for the CVD apparatus to improve the uniformity of the source gas concentration during the reaction.

FIG. 5 is a schematic view of a commonly used single-wafer cold-wall type LPCVD. As shown in the figure, a silicon substrate (wafer) 2 placed on a susceptor 1 on which a heater 6 is disposed on the lower side is disposed in a chamber 3, and a water cooling tube 4 is disposed on a side wall of the chamber 3. Is cooled to form a cold wall 3a.

The cooling of the side wall is performed so that the raw material gas 5 introduced into the chamber 3 as a reaction chamber via the gas inlet does not react near the side wall.

[0005]

In the cold wall type CVD apparatus as described above, when a source gas having a low boiling point such as tungsten hexafluoride (WF ₆ ) is used to form a thin film such as tungsten (W). , WF ₆ gas easily adsorbs on the side wall of the chamber. Accordingly, the partial pressure of the raw material gas supplied into the chamber changes due to the adsorption, and the reaction speed for forming W on the silicon substrate 2 changes, thereby impairing the uniformity of the formed W thin film. Will be. In addition, since the amount of gas adsorbed on the side wall of the chamber 3 changes depending on a gas bonding state or the like, uniformity between wafer lots deteriorates.

When the chamber side wall is heated to solve the above-mentioned problem of adsorption, the entire apparatus is heated, and the O-ring and the apparatus, which are necessary parts for maintaining the inside of the chamber 3 at a vacuum, are controlled. There is a possibility of giving an obstacle to wiring and the like. Therefore, it is not preferable to heat the chamber side wall to about 100 ° C. or more.
In addition, the apparatus imposes a heavy load on air conditioning of the installed clean room, and in practice, a temperature around 50 ° C. is a limit. Therefore, there is a problem in the CVD apparatus when it is desired to keep the side wall at a temperature of 50 ° C. or more.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a side wall heating type CVD apparatus capable of forming a CVD film having a uniform film thickness using a raw material gas which is easily adsorbed on a chamber side wall, and a film forming method using the apparatus. With the goal.

[0008]

According to the present invention, there is provided a reaction chamber, a support for mounting a semiconductor substrate, and a semiconductor base.
Source gas for supplying a source gas for forming a thin film on a plate
A CVD apparatus comprising: a supply unit;
Heating the placed semiconductor substrate, the semiconductor substrate and the
Provided in the reaction chamber to maintain the vicinity at the first temperature;
Substrate heating means and the inner wall of the reaction chamber separately from the substrate heating means.
To maintain the inner wall at a second temperature by heating
And an inner wall heating means provided on the inner wall .

[0009] According to the present invention, the above object is also achieved by the above-mentioned CV.
When forming a film using the D apparatus, tungsten hexafluoride is used as the source gas, and the temperature of the inner wall of the reaction chamber is set to 45.
The problem is solved by a film forming method using a CVD apparatus characterized in that the temperature is maintained at a temperature of not less than ° C.

[0010] Further, according to the present invention, the above object is achieved by the above-mentioned C.
The problem is solved by a film forming method using a CVD device, wherein a blanket tungsten film is formed when forming a film using a VD device.

Further, according to the present invention, the above object is achieved by the above-mentioned C.
The problem is solved by a film forming method using a CVD apparatus, wherein a tungsten silicide film is formed when forming a film using a VD apparatus.

[0012]

According to the present invention, the reaction chamber shown in FIG.
A support in the chamber 13 (hereinafter referred to as a susceptor)
U) A semiconductor substrate is placed on 1 and source gas supply means is used.
A source gas 5 is supplied into the reaction chamber, and a thin film is formed on the semiconductor substrate.
Is formed, on the other hand, the half mounted on the susceptor 1
The conductor substrate is heated by substrate heating means (hereinafter, IR lamp) 7.
The semiconductor substrate and its vicinity are heated to a first temperature.
Is held. On the other hand, it is provided in the wall of the chamber 13
Inner wall heating means (hereinafter referred to as heater) 1 shown in FIG.
6, the inner wall of the chamber 13 separately from the IR lamp 7
Is heated and its inner wall is maintained at the second temperature. Follow
In the chamber inner wall 14 of the CVD apparatus,
Keep the temperature near the wall above the boiling point of the source gas and the source gas
Can be maintained at a temperature equal to or lower than the decomposition temperature. to this
Accordingly, it is possible to prevent the source gas 5 from being adsorbed on the inner wall 14 of the chamber . Therefore, a predetermined amount of source gas can be effectively and stably used for the film formation reaction,
The uniformity of film formation can be improved.

The CVD apparatus of the present invention is effectively used for forming a film of a blanket tungsten, a tungsten silicide, etc. using a particularly easily adsorbed source gas, for example, tungsten hexafluoride.

Further, according to the present invention, by cooling the outer wall 15 of the reaction chamber, it is possible to suppress a problem caused by a temperature rise outside the apparatus.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic sectional view showing a side wall heating type CVD apparatus according to the present invention. As shown in FIG. 1, the side wall heating type CVD apparatus according to the present invention, after the inner wall heating shown in detail in FIG. 2, the chamber side wall 10 having the function of outer wall cooling
Having. A silicon substrate (wafer) 2 is placed on a susceptor 1 similar to a conventional apparatus in a chamber 13 as a reaction chamber having a chamber side wall 10, and the susceptor 1 is heated to a predetermined temperature by an IR lamp (infrared lamp) 7. To maintain the silicon substrate 2 and its vicinity at the reaction temperature. The silicon substrate 2
Are clamped by the clamp mechanism 8.

The source gas 5 mixed in the source gas mixing chamber 12 through the source gas supply ring 11 is fed into the chamber 13 by a vacuum exhaust pump (not shown), and the reaction gas is generated on the silicon substrate 2. Deposit things.

FIG. 2 is a schematic view showing one embodiment of the chamber side wall according to the present invention. As shown in FIG.
The chamber side wall 10 is made of Al. A heater 16 made of nichrome wire is provided on the inner wall 14 of the chamber, and a water cooling pipe 17 is provided on the outer wall 15. Cooling water of about 15 to 20 ° C. is supplied to the water cooling pipe 17 so that the outside of the chamber is not affected by the heating of the inside. A heat insulating layer 18 of alumina or the like is provided between the heater 16 and the water cooling tube 17 on the side wall 10 of the chamber so as not to release the heat of the heater to the outside. As shown in FIG. 2B, a water cooling tube 20 may be provided between the heaters 16 of the present embodiment to provide a cooling function to the inner wall 14, so that the temperature of the inner wall 14 can be further controlled.

One method for forming blanket tungsten (hereinafter, BLK-W) using the above-described CVD apparatus will be described. BLK-W CVD film deposition conditions were as follows.

Reaction temperature (first temperature) : 450 ° C. Chamber pressure: 10 KPa Raw material gas composition: WF ₆ / H ₂ = 25/500 sccm In this embodiment, the heater 16 inside the chamber is heated to 45 ° C.
(Second temperature) , while cooling water maintained at about 20 ° C. was flowed through the water cooling pipe 17 outside the chamber.

[0021] Figures 3 and 4 as in the present embodiment, when the chamber wall temperature and 45 ° C., and as a comparative example 20
The result of the characteristics of the BLK-WCVD film at a temperature of ° C is shown.
The horizontal axis in FIGS. 3 and 4 shows the processing number of the wafer as the Run Number, while the vertical axis shows the sheet resistance (minimum value Min, average Ave, maximum value Max). Assuming that the resistivity is constant, the sheet resistance is inversely proportional to the film thickness of the W thin film, and the distribution tendency of the sheet resistance value shown in FIG.

[0022] If the chamber wall temperature to 20 ° C., as shown in FIG. 4, while the 15% 10S also the sheet resistance is increased, the chamber wall temperature 45 ° C.
In this case, there was only a 3% increase as shown in FIG. In addition, it can be seen that the film thickness distribution in the wafer surface is deteriorated at 20 ° C. Therefore, the use of the apparatus of the present invention can suppress a decrease in the film thickness distribution between wafer lots.

Next, an embodiment in which a WSi-CVD film is formed by using the CVD apparatus shown in FIGS. This example was performed under the following conditions.

Reaction temperature: 400 ° C. Chamber pressure: 100 Pa Raw material Gas composition: WF ₆ / SiH ₄ / Ar = 3/35
0/500 sccm The chamber inner wall temperature is kept constant at 50 ° C. According to this method, the thickness distribution of the WSi film obtained is 4
As in the case of 5 ° C., it could be suppressed to within 3%. W
In the step of forming the Si-CVD film, as shown in the above-described formation conditions, the WF ₆ gas having high adsorptivity is used at a small flow rate.

[0025]

As described above, the CV according to the present invention is
According to the D apparatus, the semiconductor substrate placed on the support is heated.
Then, the semiconductor substrate and its vicinity are kept at a first temperature.
An inner wall heating means is provided on the inner wall of the reaction chamber separately from the substrate heating means.
This inner wall heating means heats the inner wall of the reaction chamber
The inner wall is maintained at the second temperature. In this configuration
Therefore, the temperature atmosphere in the semiconductor substrate and its vicinity and the reaction chamber
Since the temperature and atmosphere of the inner wall can be controlled separately and independently,
If the temperature near the inner wall of the reaction chamber is higher than the boiling point of the raw material gas,
Can be adjusted below the decomposition temperature of its raw material gas
You. Therefore, a predetermined amount of source gas is adsorbed on the inner wall of the reaction chamber.
Without any pressure, each semi-conductive part is stable and effective
It can be introduced to the film formation surface of the body substrate. This allows
The film is homogeneous not only in the plane of the semiconductor substrate but also between lots.
Deposition of CVD film with good thickness distribution on semiconductor substrate
Can be.

Further, since the material gas is prevented from being adsorbed on the side wall of the reaction chamber, the material gas can be effectively used for the film forming reaction.

Furthermore, in the CVD apparatus of the present invention, the outer wall of the reaction chamber is cooled to about 10 to 20 ° C.
The inner wall of the reaction chamber can be maintained at a high temperature without adversely affecting the external wiring and equipment such as air conditioning of the D apparatus.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a side wall heating type reduced pressure CVD apparatus according to the present invention.

FIG. 2 is a schematic sectional view showing a structure of a chamber side wall according to the present invention.

FIG. 3 is a graph showing the characteristic results of a blanket tungsten CVD film according to the present invention when the temperature of the inner wall of the chamber is 45 ° C.

FIG. 4 is a diagram showing the characteristic results of the blanket tungsten CVD film according to the present invention when the chamber inner wall temperature is set to 20 ° C.

FIG. 5 shows a conventional cold wall (side wall cooling) type decompression C
It is a VD device.

[Explanation of symbols]

 Reference Signs List 1 susceptor 2 silicon substrate (wafer) 3 chamber (reaction chamber) 4 water cooling tube 5 source gas 6,7 heater 8 clamp mechanism 10 chamber side wall 11 source gas supply ring 12 source gas mixing chamber 13 chamber (reaction chamber) 16 heater 17, 20 water cooling tube 18 heat insulation layer

Claims (6)

(57) [Claims] 1. A CVD apparatus comprising a reaction chamber, a support for mounting a semiconductor substrate, and source gas supply means for supplying a source gas for forming a thin film on a semiconductor substrate. A substrate heating unit provided in the reaction chamber for heating the placed semiconductor substrate and maintaining the semiconductor substrate and the vicinity thereof at a first temperature; and an inner wall of the reaction chamber separately from the substrate heating unit. An inner wall heating means provided on an inner wall of the reaction chamber for heating the inner wall to maintain the inner temperature at a second temperature. 2. The method according to claim 1, wherein the temperature in the vicinity of the inner wall of the reaction chamber is set to be higher than the boiling point of the raw material gas and lower than the decomposition temperature of the raw material gas by the inner wall heating means.
3. The CVD apparatus according to claim 1. Wherein the inner wall of the reaction chamber CVD apparatus according to claim 1, wherein the or to Ru a cooling means to the outer wall. 4. When forming a film by using the CVD apparatus according to claim 1, tungsten hexafluoride is used as the source gas, and the temperature of the inner wall of the reaction chamber is maintained at 45 ° C. or higher. A film forming method using a CVD apparatus to perform the method. 5. A film forming method using a CVD apparatus, wherein a blanket tungsten film is formed when forming a film using the CVD apparatus according to claim 1. 6. A film forming method using a CVD apparatus, wherein a tungsten silicide film is formed when forming a film using the CVD apparatus according to claim 1.