JP3569376B2 - Method for manufacturing semiconductor device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a coating method and a semiconductor manufacturing apparatus used therefor, and more particularly to a technique which is effective when applied to prevention of metal contamination on a semiconductor wafer in a horizontal low-pressure CVD (Chemical Vapor Deposition) apparatus.
[0002]
[Prior art]
According to studies made by the present inventors, in a horizontal low-pressure CVD apparatus for forming a thin film on a semiconductor wafer while keeping a reaction tube in a reduced pressure state, silicon carbide (SiC) is used as a material of a process tube serving as a reaction tube. I have.
[0003]
As an example describing this kind of semiconductor manufacturing equipment in detail, see, for example, Masashi Oshima (ed.), November 25, 1994, published by the Industrial Research Institute, Electronic Materials November issue, “Super LSI Manufacturing and Testing Equipment”. Guidebook <1995 edition>"P44 to P51, and this document describes the structure and the like in various CVD apparatuses.
[0004]
[Problems to be solved by the invention]
However, the present inventor has found that the horizontal low-pressure CVD apparatus as described above has the following problems.
[0005]
That is, the process tube made of the SiC material has a large content of heavy metals such as iron (Fe), and the semiconductor wafer is contaminated by impurities of these heavy metals at the time of film formation, causing a problem of poor quality. is there.
[0006]
An object of the present invention is to provide a coating method capable of reliably preventing a semiconductor wafer from being contaminated by impurities such as heavy metals generated from a reaction tube for forming a film by a CVD reaction, and a semiconductor manufacturing apparatus used therefor. .
[0007]
The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.
[0008]
[Means for Solving the Problems]
The following is a brief description of an outline of typical inventions disclosed in the present application.
[0009]
That is, in the method of manufacturing a semiconductor device according to the present invention, a reaction gas comprising an element constituting a thin film material is supplied to a reaction tube for forming a film on a semiconductor wafer, and a CVD reaction is performed with a predetermined excitation energy to form a reaction gas on the surface of the semiconductor wafer. The same thin film as the thin film to be formed is formed and coated on the inner surface of the reaction tube, and a semiconductor wafer is transferred into the reaction tube to form a film .
[0010]
Thus, the contamination of the semiconductor wafer with the heavy metal generated from the reaction tube during the film formation by the CVD reaction can be reduced.
[0011]
In the method of manufacturing a semiconductor device according to the present invention, a coating is performed by forming a thin film on the inner surface of the reaction tube by a CVD reaction using heat as excitation energy while keeping the inside of the reaction tube under reduced pressure.
[0012]
Thereby, the same thin film as the thin film formed on the surface of the semiconductor wafer can be efficiently and quickly coated on the inner surface of the reaction tube.
[0013]
Further, in the method of manufacturing a semiconductor device according to the present invention, the reaction gas is supplied from one end of the reaction tube toward the other end, and the reaction gas is supplied near one end of the reaction tube where the reaction gas is introduced. The heating is performed at a temperature equal to or higher than the temperature at the center of the tube, and the vicinity of the other end of the reaction tube is heated at a higher temperature than the vicinity of the center of the reaction tube.
[0014]
As a result, the film forming rate of the thin film formed on the inner surface of the reaction tube becomes uniform, and the same thin film as the thin film formed on the surface of the semiconductor wafer efficiently on the inner surface of the reaction tube in a short time by one coating. It can be formed with a film thickness.
[0015]
Further, in the method of manufacturing a semiconductor device according to the present invention, the reaction gas is supplied from one end of the reaction tube toward the other end, and the temperature near the one end of the reaction tube is determined based on the temperature of the center of the reaction tube. was heated to a low temperature, a first step of heating the other end temperature in the vicinity of the reaction tube to the central portion near neighbor by higher temperature than the reaction tube, one end from the other end of the reaction tube The reaction gas is supplied toward the reaction tube , and the vicinity of one end of the reaction tube is heated to a temperature higher than the temperature of the center of the reaction tube, and the temperature near the other end of the reaction tube is measured at the center of the reaction tube. and it has a second step of heating a near-neighbor by remote low temperatures.
[0016]
As a result, the same thin film as the thin film formed on the surface of the semiconductor wafer can be efficiently formed in a short time on the inner surface of the reaction tube.
[0017]
Further, in the method for manufacturing a semiconductor device according to the present invention, the thickness of the thin film formed on the inner surface of the reaction tube is 0.8 μm or more.
[0018]
Accordingly, it is possible to reliably prevent heavy metals contained in the reaction tube from permeating from the thin film formed on the inner surface of the reaction tube.
[0019]
Further, in the method of manufacturing a semiconductor device according to the present invention, a reaction gas composed of an element constituting a thin film material is supplied to a reaction tube for forming a film on a semiconductor wafer, and a CVD reaction is performed with a predetermined excitation energy. The coating is performed by forming a thin film for preventing contamination of the semiconductor wafer by the heavy metal on the inner surface of the reaction tube, and thereafter, transferring the semiconductor wafer into the reaction tube to form a film.
[0020]
As a result, the same thin film as the thin film formed on the surface of the semiconductor wafer can be efficiently formed in a short time on the inner surface of the reaction tube.
[0021]
As described above, coating for preventing heavy metal contamination can be easily performed on the inner surface of the reaction tube at low cost, defects of the semiconductor device due to heavy metal contamination can be reduced, and manufacturing efficiency can be improved.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0023]
(Embodiment 1)
FIG. 1 is an external perspective view of a horizontal low-pressure CVD apparatus according to Embodiment 1 of the present invention, with a part thereof cut away, and FIG. 2 is an explanatory view of a process tube of the horizontal low-pressure CVD apparatus according to Embodiment 1 of the present invention.
[0024]
In the first embodiment, a horizontal low-pressure CVD apparatus (semiconductor manufacturing apparatus) 1 which is a film forming apparatus is provided with a furnace body 2 which is an apparatus part for forming a thin film at a central portion.
[0025]
A reaction chamber 3 for forming a film of the semiconductor wafer W is provided on one side of the furnace body 2, and a transfer section 4 for transferring the semiconductor wafer W is provided on the other side.
[0026]
Further, the reaction chamber 3 is provided with a tubular reaction tube 3a which is a film forming unit for forming a thin film on the semiconductor wafer W, and a heater for heating (heating means) is provided near the outer periphery of the reaction tube 3a. ) 3b are provided.
[0027]
Further, a lid 3c for sealing the opening is provided at one opening of the reaction tube 3a, and is automatically opened and closed by a motor or the like.
[0028]
Further, the transfer section 4 is provided with a board transfer device 4a for transferring a board HB, which is a jig for holding the semiconductor wafer W, into and out of the reaction tube 3a. The board HB holding the wafer W is transferred into the reaction tube 3a by the board transfer device 4a.
[0029]
Next, the horizontal low-pressure CVD apparatus 1 is provided with an exhaust unit 5 adjacent to the reaction chamber 3, and the exhaust unit 5a is provided with a vacuum pump 5a for reducing the pressure inside the reaction tube 3a to a predetermined pressure. . The vacuum pump 5a is connected to the other opening of the reaction tube 3a by a pipe 5b. The vacuum pump 5a and the pipe 5b constitute a pressure reducing means.
[0030]
Further, the horizontal low-pressure CVD apparatus 1 is provided with a control unit 6 for controlling the horizontal low-pressure CVD apparatus 1 adjacent to the transport unit 4, and in the vicinity of the reaction chamber 3, one or more of the elements constituting the thin film material. A gas supply unit 7 for supplying a reaction gas such as several kinds of compound gases and simple gases to the reaction tube 3a while controlling the flow rate is provided.
[0031]
The motor for driving the board transfer device 4a, the vacuum pump 5a, the gas supply unit 7, and the lid 3c is controlled by a control circuit 6a provided in the control unit 6.
[0032]
Next, the configuration around the reaction tube 3a and the heater 3b will be described in detail with reference to FIG.
[0033]
First, in the vicinity of one opening of the reaction tube 3a, a pipe 7a for introducing the reaction gas supplied from the gas supply unit 7 (FIG. 1) described above is provided, and in one opening of the reaction tube 3a, A lid 3c for sealing the opening is provided. The gas supply unit 7 and the pipe 7a constitute a gas supply unit.
[0034]
Further, a heater 3b is provided near the outer peripheral portion of the reaction tube 3a. The heater 3b has a heater 3b ₁ located near the other opening of the reaction tube 3a to which the pipe 5b is connected, a heater 3b ₂ located at the center of the reaction tube 3a, and a reaction tube 3a hermetically closed by a lid 3c. and it is configured from a heater 3b ₃ located near one opening of the.
[0035]
And these heater 3b ₁ ~3b _3, the temperature control is performed by the control circuit section 6a in the controller 6 (FIG. 1) described above independently.
[0036]
Next, the operation of the present embodiment will be described.
[0037]
First, setting for coating the inside of the reaction tube 3a is performed from an operation unit or the like provided in the control unit 6. When the setting is performed, the control circuit 6a drives the motor to move the lid 3c, closes one opening of the reaction tube 3a, and provides the vacuum pump 5a and the heater 3b ₁ provided in the exhaust unit 5. To 3b ₃ to start the coating operation of the inner surface of the reaction tube 3a.
[0038]
For example, if the resulting film is a nitride _(Si 3 _{N 4)} film, the temperature distribution of the heater _3b 1 _{~3b 3,} the heater 3b ₁ is 830 ° C. approximately positioned on the other near the opening of the reaction tube 3a, reaction The heater 3b ₂ located at the center of the tube 3a and the heater 3b ₃ located near one opening of the reaction tube 3a are set to about 780 ° C.
[0039]
Here, the heating temperature of the heater 3b ₁ has a high temperature of about 830 ° C. is to improve the reaction rate of the other near the opening of the reaction tube 3a the concentration of the reaction gas becomes thinner. Further, the heating temperature of the heater 3b ₂ may be a temperature higher than the heater 3b _3.
[0040]
Further, the pressure in the reaction tube 3a is reduced to a pressure of about 20 Pascal to about 30 Pascal, which is a pressure at the time of film formation of the semiconductor wafer W or higher.
[0041]
The control circuit 6a, and controls the gas supply unit 7 performs control so specifically to provide the same flow rate or more reactive gas during the formation of the semiconductor wafer W into the reaction tube 3a.
[0042]
Then, film formation is performed under these conditions until a thin film of about 1 μm is formed on all inner surfaces of the reaction tube 3a. Here, the reason why the thickness of the thin film formed on the inner surface of the reaction tube 3a is about 1 μm is that the thickness of the thin film formed on the inner surface of the reaction tube 3a is 0.8 μm or more. This is because it is possible to prevent heavy metal such as iron, which is formed on the inner surface of the reaction tube 3a, from passing through the thin film and contaminating the semiconductor wafer W.
[0043]
Thereafter, the board HB holding the semiconductor wafer W is transferred into the reaction tube 3a by the boat transfer device 4a provided in the transfer unit 4, and the semiconductor wafer is formed.
[0044]
Thus, according to the first embodiment, a thin film of about 1 μm or more is formed on all inner surfaces of the reaction tube 3a with the reaction gas composed of the elements constituting the thin film material, and is coated. It is possible to prevent contamination of the semiconductor wafer W by the heavy metal.
[0045]
(Embodiment 2)
FIG. 3 is an explanatory view of a horizontal low-pressure CVD apparatus according to Embodiment 2 of the present invention.
[0046]
In the second embodiment, as shown in FIG. 3, near one opening of a reaction tube 3a provided in a horizontal low-pressure CVD device (semiconductor manufacturing device) 1a, a vacuum pump for reducing the pressure in the reaction tube 3a is provided. connecting portion 5a and the connected pipe 5c and connected pipe 7b to the gas supply unit 7 are connected (first gas inlet) 3a ₁ and the connection part (first exhaust portion) 3a ₂ provided ing.
[0047]
Also, near the other opening of the reaction tube 3a, a connection portion to which a pipe 7c also connected to the gas supply unit 7 and a pipe 5d connected to a vacuum pump 5a for reducing the pressure in the reaction tube 3a are connected. (second exhaust section) 3a ₃ and the connecting portion (the second gas introducing portion) 3a ₄ is provided.
[0048]
Further, these pipes 5c, 5d, 7b, 7c are provided with, for example, valves 8 to 8c such as a conductance valve and a switching valve, and a heater is provided near the outer peripheral portion of the reaction tube 3a as in the first embodiment. 3b is provided.
[0049]
The vacuum pump 5a, the pipes 5c and 5d, and the valves 8 and 8a constitute a pressure reducing unit, and the gas supply unit 7, the pipes 7b and 7c, and the valves 8b and 8c constitute a gas supplying unit.
[0050]
Similarly, the configuration of the heater 3b also includes a heater 3b ₁ located near the other opening of the reaction tube 3a, a heater 3b ₂ located at the center of the reaction tube 3a, and a reaction tube 3a sealed by the lid 3c. and it is configured from a heater 3b ₃ located near one opening of the.
[0051]
In addition, these heaters _3b 1 _{~3b 3,} the gas supply unit 7, the vacuum pump 5a and valve 8~8c similarly, the control circuit 6a (Embodiment 1 which controls all the control in the horizontal low-pressure CVD apparatus 1a, Fig. 1 ).
[0052]
Next, the operation of the present embodiment will be described.
[0053]
First, the controller 6 performs setting for coating the inside of the reaction tube 3a. When the setting is performed, the control circuit 6a, sealing the one opening of the reaction tube 3a to move the lid 3c by driving the motor, vacuum pump 5a provided in the exhaust unit 5, and a heater 3b ₁ ~ 3b ₃ is operated to start coating the inner surface of the reaction tube 3a.
[0054]
By closing the valves 8 and 8c, the control circuit 6a reacts one or several kinds of compound gas, elemental gas, or the like composed of elements constituting the thin film material from one opening to the other opening of the reaction tube 3a. Let the gas flow.
[0055]
For example, if the resulting film is a nitride _(Si 3 _{N 4)} film, the temperature distribution of the heater _3b 1 _{~3b 3,} the heater 3b ₁ is 830 ° C. approximately positioned on the other near the opening of the reaction tube 3a, reaction heater 3b ₃ heater 3b ₂ is located near one opening of 780 ° C. about as well as the reaction tube 3a positioned in the center of the tube 3a is about 750 ° C..
[0056]
The pressure in the reaction tube 3a is reduced to a pressure of about 20 Pascal, which is the pressure at the time of film formation of the semiconductor wafer W, and the flow rate of the reaction gas is the same as that at the time of film formation of the semiconductor wafer W in the reaction tube 3a. The control circuit 6a controls the flow rate so as to be supplied to the reaction tube 3a.
[0057]
Then, film formation is performed under these conditions until the thickness of the thin film near the other opening of the reaction tube 3a becomes about 1 μm or more. In addition, since the film forming rate is low near the one opening of the reaction tube 3a serving as the supply portion of the reaction gas, the thickness of the thin film is thinner than the central portion of the reaction tube 3a and the vicinity of the other opening. .
[0058]
Thereafter, the control circuit 6a opens the valves 8, 8c and closes the valves 8a, 8b, so that the reaction gas flows from the other opening of the reaction tube 3a to one opening.
[0059]
The control circuit 6a, a heater 3b ₂ the temperature distribution of the heater _3b 1 _{~3b 3,} the heater 3b ₁ is about 750 ° C. positioned on the other near the opening of the reaction tube 3a, which is located in the center of the reaction tube 3a Is changed to about 780 ° C. and about 830 ° C. for 3b ₃ located near one opening of the reaction tube 3a.
[0060]
Further, the pressure in the reaction tube 3a is reduced to about 20 Pascal, which is the pressure at the time of film formation of the semiconductor wafer W, and the flow rate of the reaction gas is the same as that at the time of film formation of the semiconductor wafer W in the reaction tube 3a. The control circuit 6a controls the flow rate so as to be supplied to the reaction tube 3a.
[0061]
Under these conditions, when film formation is performed again until the thickness of the thin film near one opening of the reaction tube 3a becomes about 1 μm or more, the other opening of the reaction tube 3a serving as a supply portion of the reaction gas is formed. Since the film forming rate is low in the vicinity, the thickness of the thin film is formed to be thinner than the central part of the reaction tube 3a and the vicinity of the other opening, and a thin film of about 1 μm or more is uniformly formed on the inner surface of the reaction tube 3a. Is formed, and the coating is performed.
[0062]
Thereafter, the board HB holding the semiconductor wafer W is transferred into the reaction tube 3a by the boat transfer device 4a provided in the transfer unit 4, and the semiconductor wafer is formed.
[0063]
Thereby, in the second embodiment, the entirety of the inner surface of the reaction tube 3a is coated with a thin film of about 1 μm or more with the reaction gas composed of the elements constituting the thin film material. W contamination can be prevented.
[0064]
As described above, the invention made by the inventor has been specifically described based on the embodiment of the invention. However, the invention is not limited to the embodiment, and can be variously modified without departing from the gist of the invention. Needless to say, there is.
[0065]
For example, in the first and second embodiments, the coating on the inner surface of the reaction tube for forming a film in the horizontal low-pressure CVD apparatus is described. However, the same thin film as the thin film formed on the surface of the semiconductor wafer is coated on the inner surface of the reaction tube. Can be used in a semiconductor manufacturing apparatus in which a reaction chamber in which a reaction is performed, such as a plasma CVD apparatus or another CVD apparatus or a diffusion apparatus, is made of a SiC material.
[0066]
【The invention's effect】
The effects obtained by typical aspects of the invention disclosed in the present application will be briefly described as follows.
[0067]
(1) According to the present invention, the same thin film as the thin film formed on the surface of a semiconductor wafer can be efficiently and inexpensively coated on the inner surface of a reaction tube to prevent contamination of a semiconductor wafer by heavy metals generated from the reaction tube itself. can do.
[0068]
(2) Further, according to the present invention, a device or equipment for performing coating for preventing the generation of heavy metals on the inner surface of the reaction tube is not required, and a semiconductor wafer capable of flexibly preventing the generation of heavy metals on the inner surface of the reaction tube at low cost. The same thin film as the thin film formed on the surface can be coated.
[0069]
(3) Further, in the present invention, according to the above (1) and (2), defects of the semiconductor device due to heavy metal contamination can be reduced, and manufacturing efficiency can be improved.
[Brief description of the drawings]
FIG. 1 is an external perspective view of a horizontal low-pressure CVD apparatus according to a first embodiment of the present invention, with a part cut away.
FIG. 2 is an explanatory view of a process tube of the horizontal low-pressure CVD apparatus according to the first embodiment of the present invention.
FIG. 3 is an explanatory diagram of a horizontal low-pressure CVD apparatus according to a second embodiment of the present invention.
[Explanation of symbols]
1 Horizontal low-pressure CVD equipment (semiconductor manufacturing equipment)
1a Horizontal low-pressure CVD equipment (semiconductor manufacturing equipment)
2 Furnace body 3 Reaction chamber 3a Reaction tube 3a ₁ connection part (first gas introduction part)
3a ₂ connection part (first exhaust part)
3a ₃ connection part (second exhaust part)
3a ₄ connection part (second gas introduction part)
3b heater (heating means)
3b ₁ heater 3b ₂ heater 3b ₃ heater 3c lid 4 transfer unit 4a board transfer device 5 exhaust unit 5a vacuum pump 5b pipe 5c pipe 5d pipe 6 control unit 6a control circuit 7 gas supply unit 7a pipe 7b pipe 7c pipe 8 to 8c valve W Semiconductor wafer HB board

Claims (2)

In a reaction tube for forming a reaction gas composed of an element constituting a thin film material on a semiconductor wafer , temperature control is performed separately on one side, near the center, and in the region near the other end of the reaction tube. Providing means,
The inside of the reaction tube is kept under reduced pressure, a reaction gas is supplied from one end of the reaction tube toward the other end, and the vicinity of one end of the reaction tube into which the reaction gas is introduced is the reaction tube. And heating the vicinity of the other end of the reaction tube at a temperature higher than the vicinity of the center of the reaction tube, and causing a CVD reaction by excitation energy using heat. Forming a thin film on the inner surface of the reaction tube and performing coating,
Thereafter, a film is formed by transporting the semiconductor wafer into the reaction tube. In a reaction tube for forming a reaction gas composed of an element constituting a thin film material on a semiconductor wafer, temperature control is performed separately on one side, near the center, and in the region near the other end of the reaction tube. Providing means,
The inside of the reaction tube is kept in a reduced pressure state, a reaction gas is supplied from one end of the reaction tube toward the other end, and the vicinity of one end of the reaction tube is lower than the temperature of the center of the reaction tube. A first step of heating the vicinity of the other end of the reaction tube to a temperature higher than the vicinity of the center of the reaction tube, and one of the other ends of the reaction tube from the other end of the reaction tube. A reaction gas is supplied toward the end, and the vicinity of one end of the reaction tube is heated to a temperature higher than the temperature of the center of the reaction tube, and the temperature near the other end of the reaction tube is increased. A second step of heating to a temperature lower than the vicinity of the center of the reaction tube, thereby causing a CVD reaction by excitation energy using heat, forming a thin film on the inner surface of the reaction tube, and performing coating;
Thereafter, a film is formed by transporting the semiconductor wafer into the reaction tube . August 29, 2003 Filing of change of applicant name

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