JP4303409B2 - Method for depositing conductive plug and method for manufacturing semiconductor device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for depositing a conductive plug and a method for manufacturing a semiconductor device , and more particularly, to a method for depositing a conductive plug and a semiconductor with improved step coverage when tungsten is buried in a contact hole or a via hole of the semiconductor device. The present invention relates to a device manufacturing method .
[0002]
[Prior art]
The semiconductor device has a contact hole or a via hole (hereinafter, collectively referred to as a contact hole) that conducts the electrode and the wiring of the element or the wiring and the wiring. For this reason, several techniques for embedding a conductive plug (tungsten) in a contact hole have been developed (for example, JP-A-9-32137). Further, as the miniaturization progresses, the film thickness does not progress as much as the pattern size, and the aspect ratio, which is the ratio of the contact hole depth to the contact hole diameter, tends to increase.
[0003]
FIG. 2 shows a conventional method for depositing a conductive plug. As shown in FIG. 2A, first, a barrier metal 1 is formed on the side wall of a contact hole of a semiconductor device by a CVD method. Next, as shown in FIG. 4B, a reactive gas having a predetermined pressure is continuously guided to form a tungsten nucleation film 4 on the barrier metal 1. As shown in FIG. 6C, a reactive gas having a predetermined pressure is continuously guided to form a tungsten buried film 5 on the tungsten nucleation film 4 so as to bury a contact hole.
[0004]
[Problems to be solved by the invention]
In the above conventional conductive plug deposition method, the reactive gas is continuously guided, so that the side reactive product gas generated in the contact hole having a high aspect ratio is accumulated at the bottom of the contact hole, and the reactive gas is collected at the bottom of the contact hole. Can not lead to enough. As a result, the growth speed of the tungsten nucleation film 4 is slow and the film thickness is reduced at the bottom of the contact hole, so that the tungsten buried film 5 cannot be sufficiently grown at the bottom of the contact hole and a void 6 is generated.
[0005]
When the void 6 is generated, when the wiring is formed in the upper part of the contact hole in a later process, the void 6 may be exposed and the tungsten buried film 5 and the wiring may be disconnected. In addition, since the contact resistance or the through-hole resistance of the contact hole is increased and the step coverage is deteriorated, there is a risk that the long-term reliability is lowered and the yield is lowered.
[0006]
The present invention has been made in order to solve the above-described problems of the prior art, and a conductive plug deposition method and semiconductor device for improving step coverage of a contact hole having a high aspect ratio . An object is to provide a manufacturing method .
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the conductive plug deposition method of the present invention is a method of introducing a reactive gas into a processing chamber and depositing the conductive plug in a through hole or a contact hole. It is characterized in that a gas introduction step for introducing a gas and advancing deposition and a gas exhaust step for exhausting the gas in the processing chamber are alternately repeated.
[0008]
In the conductive plug deposition method of the present invention, the gas introduction step and the gas exhaust step are alternately repeated a plurality of times, so that the film thickness of the film is uniform throughout, and the conductive plug covers the contact hole with good coverage. Since it is embedded, step coverage is improved.
[0009]
In the conductive plug deposition method of the present invention, it is preferable that the gas exhausting step is terminated when the processing chamber pressure becomes 1/2 to 1/10 of the processing chamber pressure in the gas introduction step. In this case, since the exhaust time of the gas exhaust step can be appropriately selected, the next gas introduction step can be performed efficiently.
[0010]
A first stage having a gas introduction step for introducing WF ₆ , SiH ₄ and H ₂ and an alternate gas exhaust step, a gas introduction step for introducing WF ₆ and H ₂ , and an alternate gas exhaust step; It is also a preferred embodiment of the present invention to sequentially have a second stage having In this case, since the tungsten nucleation film group is formed in the first stage and the tungsten buried film group is formed in the second stage, the step coverage is favorably improved.
[0011]
In the conductive plug deposition method of the present invention, the gas exhausting step may be a step of exhausting a side reactive product gas generated from the reactive gas.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a method for depositing a conductive plug of the present invention will be described with reference to the drawings based on an embodiment of the present invention. FIG. 1 shows a method for depositing a conductive plug according to an embodiment of the present invention. A semiconductor device has a contact hole with a high aspect ratio. The method for depositing the conductive plug according to the present embodiment includes a barrier metal process, a nucleation film process, and a buried film process, which are performed in this order in the processing chamber. Unlike the inside of the furnace that processes about 100 wafers at a time, the processing chamber processes one wafer.
[0013]
FIG. 4A shows a barrier metal process. First, a barrier metal 1 made of WN, T _i N, T _a N, or the like is formed on the sidewall of a contact hole of a semiconductor device by a CVD method, but a directional sputtering method or the like can also be used depending on the aspect ratio. In a contact hole having a high aspect ratio, when the barrier metal 1 is formed with good coverage, a good contact is obtained and the step coverage of tungsten is improved.
[0014]
FIG. 5B shows the nucleation film process (first stage). The nucleation film process is performed after the barrier metal process and includes a gas introduction step and a gas exhaust step. The gas introducing step, WF _6, S _i H ₄ where the pressure was set to 133-13300 [Pa], and supplies a reactive gas H _2, forming a tungsten nucleation layer group 2 on the barrier metal 1 Film. WF ₆ is set to 10 to 100 [sccm], and S _i H ₄ is set to ₄ to 50 [sccm]. In this process, by-reactive product gas is generated and collected at the bottom of the contact hole.
[0015]
In the gas exhausting step, the gas in the contact hole including the reactive gas and the side reactive product gas is exhausted. The exhaust time is selected so as to end when the processing chamber pressure becomes 1/2 to 1/10 of the gas introduction step.
[0016]
The gas introduction step and the gas exhaust step are alternately repeated a plurality of times. In the gas introduction step performed after the gas evacuation step of the tungsten nucleation film group 2, the reactive gas is sufficiently guided to the bottom of the contact hole, so that the film thickness becomes uniform. Since both steps are repeated a plurality of times, the tungsten nucleation film group 2 is formed with good coverage and the film thickness becomes 10 to 50 [nm].
[0017]
FIG. 5C shows the buried film process (second stage). The buried film process is performed after the nucleation film process, and includes a gas introduction step and a gas exhaust step as in the nucleation film process. In the gas introduction step, a reactive gas of WF ₆ and H ₂ having a pressure set to 6650 to 53200 [Pa] is supplied, and the tungsten buried film group 3 is formed on the tungsten nucleation film group 2. WF ₆ is set to 50 to 500 [sccm], and H ₂ is set to 500 to 5000 [sccm].
[0018]
In the gas exhaust step, the gas in the contact hole is exhausted as in the nucleation film process. The exhaust time is selected so as to end at a predetermined time. The gas introduction step and the gas exhaust step are alternately repeated a plurality of times. Similar to the nucleation film process, the tungsten buried film group 3 is formed with good coverage, and the film thickness becomes 50 to 500 [nm].
[0019]
Since the tungsten buried film group 3 fills the contact hole with good coverage and no void is generated, the step coverage of the conductive plug is improved.
[0020]
Reactive gas, material gas consisting of WF _6, and consists of a reducing gas consisting of S _i H ₄ or H ₂ and the like. It is preferable to introduce the reactive gas separately into the material gas and the reducing gas in advance. In the gas introduction step of the nucleation film process and the buried film process, the material gas is diffused in advance to the bottom of the contact hole, and then the reducing gas is introduced. Since the reducing gas has a higher diffusion rate than the material gas and both gases diffuse uniformly to the bottom of the contact hole, the tungsten nucleation film group 2 and the tungsten buried film group 3 with good coverage are formed. Except for the gas introduction step of the nucleation film process and the buried film process, the process is the same as described above.
[0021]
The conductive plug deposition method of the present invention can also be applied to the formation of other portions of the semiconductor device. In the case of fine wiring with a high aspect ratio, the gas introduction step and the gas exhaust step are repeated a plurality of times to form a film having a certain thickness. In the case of embedding between interlayer films, a gas introduction step and a gas exhaust step are performed in one step to form a desired film thickness.
[0022]
According to the above embodiment example, by repeating the gas introduction step and the gas exhaust step alternately a plurality of times, the film thickness of the film becomes uniform as a whole, and the conductive plug fills the contact hole with good coverage. Step coverage is improved.
[0023]
Although the present invention has been described based on the preferred embodiment, the method for depositing the conductive plug of the present invention is not limited to the configuration of the above embodiment, and the configuration of the above embodiment. The method for depositing the conductive plug with various modifications and alterations is also included in the scope of the present invention.
[0024]
【The invention's effect】
As described above, in the conductive plug deposition method of the present invention, the film introduction film thickness becomes uniform as a whole by alternately repeating the gas introduction step and the gas exhaust step a plurality of times. Since the contact hole is embedded with good coverage, step coverage is improved. For this reason, the disconnection between the contact hole and the wiring and the increase in resistance are prevented, so that the long-term reliability and yield of the semiconductor device can be prevented from decreasing.
[Brief description of the drawings]
FIG. 1 illustrates a method for depositing a conductive plug according to an embodiment of the present invention.
FIG. 2 shows a conventional method for depositing a conductive plug.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Barrier metal 2 Tungsten nucleation film group 3 Tungsten embedding film group 4 Tungsten nucleation film 5 Tungsten embedding film 6 Void

Claims (5)

In a method of depositing a conductive plug in a through hole or a contact hole by introducing a reactive gas into a processing chamber,
After pre-diffused material gas of WF ₆ gas into the process chamber, a gas introduction step you introducing a reducing gas comprising SiH _4, and a gas exhaust step for exhausting the processing chamber of the gas alternately to alternately The first stage to repeat ;
A gas introducing step for introducing a reducing gas consisting of H ₂ after a material gas consisting of WF ₆ gas is diffused in advance into the processing chamber, and a gas exhausting step for exhausting the gas in the processing chamber alternately are alternately performed. A method for depositing conductive plugs comprising sequentially repeating second steps .   2. The conductive plug deposition method according to claim 1, wherein the gas exhausting step is ended when the processing chamber pressure becomes ½ to 1/10 of the processing chamber pressure in the gas introduction step. Forming a barrier metal in a contact hole of a semiconductor device;
WF in the processing chamber ₆ After pre-diffusing a material gas consisting of gas, SiH ₄ A step of forming a nucleation film on the barrier metal by alternately repeating a gas introduction step of introducing a reducing gas and a gas exhaust step of exhausting the gas in the processing chamber alternately with the gas,
WF in the processing chamber ₆ After pre-diffusing the material gas consisting of gas, H ₂ A step of forming a buried film on the nucleation film by alternately repeating a gas introduction step for introducing a reducing gas and a gas exhaust step for exhausting the gas in the processing chamber alternately. A method for manufacturing a semiconductor device. 4. The method of manufacturing a semiconductor device according to claim 3, wherein the gas exhausting step ends when the processing chamber pressure becomes ½ to 1/10 of the processing chamber pressure in the gas introduction step. 5. The method of manufacturing a semiconductor device according to claim 3, wherein the step of forming a barrier metal in the contact hole is performed by a CVD method.

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