JP2003282530A - Substrate treatment device and method of manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently remove a natural oxide film by using plasma. <P>SOLUTION: A dry cleaning device is provided with a treatment chamber 1 in which a wafer W is treated, a plasma unit 2 where treatment gas for treating the substrate is activated with plasma and a lamp 3 for heating the wafer W disposed in the treatment chamber 1. By-products are produced on the substrate W by supplying the active species of treatment gas activated by the plasma unit 2, and the by-products are removed by heating the wafer W by the lamp 3. A shielding plate 4 preventing the infiltration of plasma light into the treatment chamber 1 from the plasma unit 2 is arranged between the plasma unit 2 and the treatment chamber 1. Thus, the by-products can be produced under a thermal environment of not higher than room temperature by using plasma. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, which efficiently removes a native oxide film and other pretreatments using plasma, and a substrate processing apparatus for carrying out the method.

[0002]

2. Description of the Related Art In the manufacture of semiconductor integrated circuits and other semiconductor devices, a wafer is repeatedly subjected to processes such as film formation and pattern etching to form a large number of desired elements. In addition, it is necessary to transfer the wafers between the processing apparatuses in the course of performing various kinds of processing. Therefore, it is unavoidable that the wafer is exposed to the atmosphere during the transfer, and the fact that a natural oxide film is generated in the exposed portion of the wafer surface due to oxygen and moisture in the atmosphere is present. Is. This natural oxide film becomes a cause of inhibiting the epitaxial growth or deteriorating the electrical characteristics of the device. Therefore, a surface treatment for removing the natural oxide film from the wafer surface may be performed as a pretreatment of the film forming step. Conventionally,
In removing the natural oxide film, a so-called wet cleaning is generally performed in which a wafer on which the natural oxide film is formed is immersed in a predetermined chemical solution and the natural oxide film is removed by the chemical solution.

However, as the degree of integration and the degree of miniaturization of semiconductor integrated circuits are promoted, the line width of the pattern, the diameter of the contact hole, etc. are also reduced. It is less than that. Therefore, there is a case where the chemical solution does not soak into the hole sufficiently, or conversely, the soaked solution cannot be discharged from the hole due to surface tension, and the natural oxide film generated at the bottom of the hole cannot be sufficiently removed. There was a problem. Further, when a laminated structure of a plurality of layers is formed on the substrate, since the etching rate is different for each layer, unevenness may occur on the hole wall surface. further,
Since the chemical solution easily penetrates into the boundary surface portion of each layer, there is a problem that the boundary surface is excessively scraped by the permeated chemical solution.

Therefore, as a solution to the above problems, it has been proposed to remove the native oxide film and perform other pretreatments by using a plasma treatment technique. This is a so-called dry cleaning method in which a natural oxide film is removed using a predetermined processing gas (etching gas) instead of wet cleaning with a chemical solution.

[0005]

However, the inventors have found that another problem may occur when the plasma processing technique is used for removing the natural oxide film. The details will be described below.

For example, the following dry cleaning methods are available. That is, for example, N ₂ , NH ₃ , and NF ₃ gases are used as a processing gas, any of the above gases is activated in a region different from the reaction chamber, and these are mixed and then introduced into the reaction chamber. Then, the activated mixed gas reacts with the natural oxide film on the wafer placed in the reaction chamber to temporarily generate a by-product on the wafer. It is known that this by-product is (NH ₄ ) ₂ SiF ₆ or NH ₄ F. These by-products are easily sublimated from the substrate by heating at 100 ° C or higher. Therefore, after the by-products are generated, the back surface of the wafer is irradiated with a lamp, or the wafer is heat-treated in a processing container different from the reaction chamber to remove the by-products.

Here, the chemical reaction when the by-products are produced from the activated mixed gas and the natural oxide film is very temperature sensitive, and it is necessary to control the temperature of the wafer finely. Moreover, according to the research conducted by the present inventors, it has been found that this chemical reaction is active particularly in a region lower than room temperature. More specifically, FIG. 4 shows the dependence of the natural oxide film removal rate (by-product production rate) on the wafer temperature. As shown in FIG. Rate of removal of natural oxide film (rate of by-product formation)
Is reduced. Therefore, in order to efficiently perform the main dry cleaning, it is desirable to process the wafer at room temperature (for example, 25 ° C.) or lower.

[0008] However, in the case of plasma of a mixed gas of N ₂ and NH _3, since particularly intense light and heat is generated, will the temperature of the reaction chamber of a wafer due to rises and vice Interferes with the product formation reaction. That is, in this dry cleaning method, the two contradictory conditions of processing the wafer at room temperature or below must be satisfied while using a plasma that generates strong light and heat. This means that other plasma processing techniques (eg conventional plasma dry cleaning method using oxygen plasma processing or hydrogen plasma processing, plasma
This is a problem unique to this dry cleaning method, which is not present in the CVD method, plasma ashing method, plasma doping method, etc.), and an early solution is desired.

Therefore, an object of the present invention is to provide a technique for efficiently removing a natural oxide film and other pretreatments while using plasma.

[0010]

According to a first aspect of the present invention which achieves this object, a processing chamber for processing a substrate as an object to be processed, and a processing gas for processing the substrate are activated by plasma. And a heating unit that heats the substrate arranged in the processing chamber, and supplies the active species of the processing gas activated by the activation unit into the processing chamber. A substrate processing apparatus which produces a by-product on the substrate and then removes the by-product by heating the substrate by the heating means, wherein the processing gas is activated by the activation means. It is characterized in that a plasma light blocking means for blocking the generated plasma light from reaching the processing chamber is provided. According to the first aspect, the plasma light shielding unit blocks the plasma light generated when the processing gas is activated by the activation unit from reaching the processing chamber, so that the plasma is generated when the by-product is generated. This prevents the temperature of the substrate (object to be processed) from rising due to the above. Therefore, it is possible to prevent the reaction rate from lowering when a by-product is produced. As a result, the natural oxide film formed on the substrate can be removed efficiently.

A second aspect of the present invention is characterized in that the substrate processing apparatus according to the first aspect further comprises cooling means for cooling the plasma light shielding means. According to the second aspect, since the cooling means cools the plasma light shielding means, it is possible to prevent thermal deterioration of the plasma light shielding means. Further, since the plasma heat generated in the activation means is prevented from being transferred to the processing chamber, the natural oxide film can be removed more efficiently.

According to a third aspect of the present invention, in the substrate processing apparatus according to the first or second aspect, a by-product is produced on the substrate under a thermal environment of room temperature or lower. Characterize.

According to a fourth aspect of the present invention, in the substrate processing apparatus according to any one of the first to third aspects, the plasma light shielding means is arranged between the activation means and the processing chamber, The light shielding plate is formed with an opening communicating from the activation means side to the processing chamber side, and the opening has an opening area that shields the plasma light and does not deactivate the active species. Is characterized by.

A fifth aspect of the present invention is the substrate processing apparatus according to any one of the first to fourth aspects, wherein the processing gas includes nitrogen-hydrogen-based gas containing nitrogen and hydrogen, and nitrogen fluoride gas. The activating means is configured to activate the nitrogen-fluoride gas by adding active species generated by activating the nitrogen-hydrogen-based gas by plasma to the nitrogen-fluoride gas. It is characterized by being.

According to a sixth aspect of the present invention, in the substrate processing apparatus according to the fifth aspect, the nitrogen-hydrogen-based gas is N ₂ and NH ₃ or a mixed gas of N ₂ and H _2. .

According to a seventh aspect of the present invention, in the substrate processing apparatus according to any one of the first to sixth aspects, the plurality of substrates can be arranged in the processing chamber, and the plurality of substrates can be collectively packaged. It is characterized in that it is processed.

An eighth aspect of the present invention is the substrate processing apparatus according to any one of the first to seventh aspects, in which the active species of the processing gas activated by the activating means is arranged in the processing chamber. It is characterized in that it is configured to be supplied by a side flow in a direction parallel to the flat surface of the substrate.

According to a ninth aspect of the present invention, by-products are formed on the substrate by supplying to the substrate active species of the processing gas obtained by activating plasma of the processing gas for treating the substrate. A method of manufacturing a semiconductor device, comprising: a by-product generation step of causing the generation; and a heating step of removing the by-product by heating the substrate to a predetermined temperature, the by-product generation step. Then, the by-product is produced while preventing plasma light and / or plasma heat generated when the processing gas is activated from reaching the substrate.

A tenth aspect of the present invention is the method for manufacturing a semiconductor device according to the ninth aspect, wherein in the by-product producing step, a by-product is produced on the substrate under a thermal environment of room temperature or lower. Is characterized by.

The eleventh aspect of the present invention is the ninth or tenth aspect.
In the method for manufacturing a semiconductor device according to the aspect 1, the processing gas contains a nitrogen-hydrogen-based gas containing nitrogen and hydrogen and a nitrogen fluoride gas, It is characterized in that the activated species generated by being activated by plasma are added to the nitrogen fluoride gas to activate the nitrogen fluoride gas and supply the activated species to the substrate.

A twelfth aspect of the present invention is the substrate processing apparatus according to the eleventh aspect, wherein the nitrogen-hydrogen gas is N 2.
It is a mixed gas of ₂ and NH ₃ or N ₂ and H ₂ .

The thirteenth aspect of the present invention is the ninth to twelfth aspects.
In the substrate processing apparatus according to any one of the aspects, the by-products are produced on the plurality of substrates in the by-product producing step, and the by-products on the plurality of substrates are collectively removed in the heating step. It is characterized by doing.

The fourteenth aspect of the present invention is the ninth to thirteenth aspects.
In the substrate processing apparatus according to any one of the aspects 1) to 2), in the by-product generation step, the active species of the processing gas are supplied as a side flow over a flat surface of the substrate in a direction parallel to the flat surface. .

[0024]

1 shows a dry cleaning device to which the present invention is applied. This dry cleaning apparatus includes a processing chamber 1 for processing a wafer (object to be processed) W, a plasma unit (activating means) 2 for activating a processing gas for processing the wafer W with plasma, and a processing chamber 1.
A lamp (heating means) for heating the wafer W placed inside
3, the activated species of the processing gas activated by the plasma unit 2 are supplied into the processing chamber 1 and reacted with the natural oxide film formed on the surface of the wafer W, so that The by-product is generated, and then the wafer W is heated by the lamp 3 to remove the by-product.

The dry cleaning device is
The greatest feature is that a light shielding plate 4 (plasma light shielding means) is provided between the plasma unit 2 and the processing chamber 1 to prevent plasma light from entering the processing chamber 1 from the plasma unit 2. Hereinafter, each part will be described in detail.

The processing chamber 1 is formed, for example, of aluminum into a polygonal shape, and its inner wall is subjected to alumite processing in order to prevent contamination of the wafer. A wafer mounting table 5 made of quartz is arranged in the processing chamber 1. The wafer mounting table 5 is configured to hold a plurality of wafers (for example, two wafers) in a multi-layered state.
Therefore, this dry cleaning apparatus can process a plurality of wafers W at one time. The wafer mounting table 5 is connected to a rotating mechanism 6 arranged outside the processing chamber 1 via a magnetic seal structure (not shown).

The processing chamber 1 has a gas introduction section for introducing the active species of the processing gas, and a gas exhaust section for exhausting the processed gas and the like in the processing chamber 1. The gas introduction part is provided with a preliminary chamber 7 for uniformly diffusing and mixing the active species supplied from the plasma unit 2 side. The light shielding plate 4 is provided at the boundary between the preliminary chamber 7 and the reaction chamber 1, and the preliminary chamber 7 and the reaction chamber 1 communicate with each other via the light shielding plate 4.
The gas exhaust unit is configured such that an exhaust pipe 8 connected to a vacuum pump or the like (not shown) is connected to the processing chamber 1 by a joint.

Here, the light shielding plate 4 will be described. Figure 2
FIG. 4 is a plan view of the light shielding plate 4. As shown in FIG. 2, the light-shielding plate 4 is formed in the plasma unit 2 in the approximate center of a single plate-shaped body.
An opening (slit) 4a communicating from the side to the processing chamber 1 side is formed. If the opening area of the opening 4a is too large, a sufficient light shielding function cannot be obtained. On the other hand, if the opening area of the opening 4a is too small, the radicals are deactivated, which rather hinders the production of by-products. Therefore, the opening 4a
Has an opening area such that active species are not deactivated while blocking plasma light.

Specifically, the opening 4a is formed in a strip shape having a longitudinal direction in the loading direction of the wafers W in the processing chamber 1 (vertical direction in FIG. 1). Its width is approximately 5 [m
m]. Further, since the light shielding plate 4 is exposed to the plasma light and the plasma heat from the plasma unit 2, the light shielding plate 4 is likely to become high temperature. Therefore, although not shown, the light shielding plate 4 is provided with a cooling means. As the cooling means, a known means such as a water-cooled chiller unit can be used.

The processing chamber 1 is provided with a window 9 that faces the wafer W in the processing chamber 1 from the lamp 3 side. Window 9
It is made of quartz and is hermetically installed in the processing chamber 1 by using an O-ring or the like (not shown).

The lamp 3 irradiates the wafer W in the processing chamber 1 with infrared rays through the window 9 and heats it to a predetermined temperature. The lamp 3 is specifically composed of a halogen lamp or the like, and has substantially the same size as the window 9.
Further, the lamp cover 31 is provided so as to surround the lamp 3.
Is installed. The inner wall of the lamp cover 31 is formed with a mirror surface as a reflection means, so that the substrate can be efficiently irradiated with infrared rays generated from the lamp 3.

The plasma unit 2 includes an active species generation chamber 21 formed of sapphire glass, a μ wave power source 22 for generating a microwave (μ) wave as an energy source for plasma generation, and this μ wave power source 22. And a waveguide 23 that efficiently transmits the μ wave generated in 1 to the active species generation chamber 21. The μ-wave power source 22 generates a μ-wave of 2.45 GHz, for example.

The active species production chamber 21 communicates with the mixed gas pipe 10 for supplying a hydrogen-nitrogen based gas containing hydrogen and nitrogen. The hydrogen-nitrogen-based gas is specifically a mixed gas of N ₂ and NH ₃ , and the mixed gas pipe 10 communicates with the N ₂ gas source 11 and the NH ₃ gas source 12. Specifically, the mixed gas pipe 10 is bifurcated midway toward the respective gas sources 11 and 12, and one of the branched pipes (N ₂ pipe) 10 a is connected to the N ₂ gas source 11. The other pipe (NH ₃ pipe) 10b is connected to the NH ₃ gas source 12. MFCs (mass flow controllers) 13 and 14 for controlling the flow rates of N ₂ gas and NH ₃ gas are provided in the respective gas pipes 10a and 10b.

Further, the active species production chamber 21 is also connected to a gas introduction pipe 15 for delivering the active species produced by activating the hydrogen-nitrogen-based gas obtained from the mixed gas pipe 10 to the processing chamber 1 side. Has been done. One end of the gas introduction pipe 15 is connected to the active species generation chamber 21, and the other end thereof is connected to the preliminary chamber 7. Also, in the middle of the gas introduction pipe 15, NF
_Three pipes 16 are connected. NF ₃ pipe 16 has one end connected to the middle of the gas introduction pipe 15, NF ₃ gas source 1 via the MFC17 for the other end to control the flow rate of NF ₃
8 is connected.

The operation of the dry cleaning device constructed as described above is as follows. From N ₂ gas source 11 to N ₂
And N ₂ gas supplied to the pipe 10a, NH ₃ and NH ₃ gas supplied from the gas source 12 to the NH ₃ pipe 10b is merged in the mixed gas piping 10, their mixed gas (hydrogen the nitrogen-containing gas) is active It is supplied to the seed generation chamber 21. The supply amounts of N ₂ gas and NH ₃ gas are independently controlled by the MFCs 13 and 14, respectively.

In the active species generation chamber 21, the mixed gas is activated by the μ wave guided from the μ wave power source 22, and active species are generated. The generated active species is sent to the gas introduction pipe 15. In the process of the active species flows through the gas introduction pipe 15 toward the pre-chamber 7, NF ₃ supplied from the NF ₃ gas source
Gas is added to the active species. As a result, the NF ₃ gas is also activated. The amount of NF ₃ gas supplied is MFC.
Controlled by 17.

Active species generated in the active species generation chamber 21 and NF
The active gas of ₃ is the spare chamber 7 through the gas introduction pipe 15.
And is diffused and uniformly mixed in the preliminary chamber 7. The mixed active gas is supplied into the processing chamber 1 through the opening 4 a of the light shielding plate 4. Specifically, the active gas is supplied by a side flow over the flat surfaces of all the wafers W arranged in the processing chamber 1 in a direction parallel to the flat surfaces. When the active gas is supplied, the rotation mechanism 6 rotates the wafer mounting table 5. As a result, the active gas becomes
A protective film, that is, a by-product is formed by reacting with the natural oxide film on the surface of the wafer W placed inside (by-product producing step).

At this time, the light shielding plate 4 is attached to the plasma unit 2
Since it plays the role of preventing plasma light and plasma heat from the side from reaching the inside of the processing chamber 1, a by-product can be formed on the surface of the wafer W in a thermal environment at room temperature or lower. Therefore, the reaction rate can be efficiently maintained, and a by-product can always be stably formed. Further, since the opening 4a is formed in a strip shape having a longitudinal direction in the stacking direction of the wafer W (vertical direction in FIG. 1), the active species are generated when the rotation mechanism 6 rotates the wafer mounting table 5. Can be uniformly supplied to all the wafers W.

When the by-products are formed on the wafer W in this way, the supply of various gases is stopped and the formation of plasma is stopped, and the residual gas in the processing chamber 1 is exhausted from the exhaust pipe 8. .

Thereafter, the wafer W is heated to a predetermined temperature (for example, 100 ° C.) or more by irradiating the wafer W with infrared rays from the lamp 3 through the window 9. At this time as well, the wafer mounting table 5 may be rotated.
As a result, the by-products formed on the surface of the wafer W are sublimated and removed (heating step). As a result, the natural oxide film formed on the surface of the wafer W is removed.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to this. For example, the plasma unit 2 may be configured by a high frequency generation source that generates an RF wave (high frequency) and an induction coil, and configured to generate plasma by the RF wave. The gas supplied to the active species generation chamber 21 is not particularly limited to N ₂ and NH _{3 as} long as it is a gas containing nitrogen and hydrogen.
_It may be ₂ and H ₂ . Further, the number of light-shielding plates 4, the number of openings 4a, and the shape of the openings 4a are not particularly limited, and may be changed appropriately. Further, in the above embodiment, the case of removing the natural oxide film formed on the wafer has been described, but it is needless to say that the present invention can be applied to the case of removing the oxide film intentionally formed on the wafer. .

[Example] The width of the opening is 1 mm,
Four light-shielding plates of 4 mm, 8 mm, and 20 mm were prepared, and the temperature change of the wafer in the by-product generation process when each light-shielding plate was used was determined. The measurement result is shown in FIG.
This figure is a graph in which the horizontal axis represents the process time [min] and the vertical axis represents the wafer temperature [° C]. This graph is obtained by measuring the temperature of the wafer for 10 minutes immediately after the start of the process, obtaining an approximate expression by natural logarithm from the data, and estimating and plotting the data of 30 to 360 minutes. When the continuous process is performed, it is estimated that the temperature change of the wafer is as shown in this graph. As can be seen from FIG. 2, there is a correlation between the temperature of the wafer and the width of the opening of the light shielding plate in the by-product generation step, and the narrower the width of the opening, the more the temperature rise of the wafer can be suppressed.

[0043]

According to the present invention, it is possible to efficiently perform removal of a natural oxide film and other pretreatments while using plasma.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a dry cleaning device according to an embodiment.

FIG. 2 is a diagram showing an example of a light shielding plate.

FIG. 3 is a diagram for explaining an effect of preventing overheating of the wafer when various slit widths of the light shielding plate are changed.

FIG. 4 is a diagram for explaining the dependency of the byproduct generation rate on the wafer temperature.

[Explanation of symbols] 1 ... Processing room 2 ... Plasma unit (activation means) 3 ... Lamp (heating means) 4 ... Shading plate (plasma light shading means)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Ogawa Unryu             3-14-20 Higashi-Nakano, Nakano-ku, Tokyo Stocks             Hitachi Kokusai Electric Co., Ltd. F term (reference) 5F004 AA14 BA03 BB05 BB26 CA04                       DA00 DA17 DA24 DA25 DB03                       EB01

Claims (3)

[Claims] 1. A processing chamber for processing a substrate, an activating means for activating a processing gas for processing the substrate by plasma, and a heating means for heating the substrate arranged in the processing chamber. By supplying an active species of the processing gas activated by the activating means into the processing chamber to generate a by-product on the substrate, and then heating the substrate by the heating means. A substrate processing apparatus for removing by-products, comprising plasma light blocking means for blocking plasma light generated when the processing gas is activated by the activation means from reaching the processing chamber. A characteristic substrate processing apparatus. 2. The substrate processing apparatus according to claim 1, further comprising cooling means for cooling the plasma light shielding means. 3. A by-product producing step of producing a by-product on a substrate by supplying to the substrate active species obtained by activating a processing gas for treating the substrate with plasma. Next, a method of manufacturing a semiconductor device, including a heating step of removing the by-product by heating the substrate to a predetermined temperature, wherein the processing gas is activated in the by-product generating step. A method of manufacturing a semiconductor device, wherein the by-product is produced while preventing plasma light and / or plasma heat that is sometimes generated from reaching the substrate.