JP2008311310A - Semiconductor manufacturing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor manufacturing apparatus capable of stably being operated for a long period of time. <P>SOLUTION: The semiconductor manufacturing apparatus includes a container 11 whose interior can be depressurized, a susceptor 13 which supports a work substrate 12 housed in the container 11, copper tube coils 14 arranged along the outer wall of the container 11, a power source 15 which supplies ac power to the coils 14 to generate plasma in the container 11, a circulating water system 16 which supplies a cooling fluid to one end 14a of each coil 14 and discharges the cooling fluid from the other end 14b of the coil 14 to circulate the cooling fluid through the copper tube of the coil 14, and a coat 17 which is formed on the interior wall of the copper tube of each coil 14 to prevent the corrosion of the coil 14 by the cooling fluid. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a semiconductor manufacturing apparatus.

2. Description of the Related Art As a semiconductor manufacturing apparatus, a process apparatus that performs film formation or etching using plasma is known (see, for example, Patent Document 1).

The process apparatus using plasma disclosed in Patent Document 1 includes a dome-shaped insulating chamber that accommodates a substrate to be processed, a coil of copper tube wound in multiple along the outer wall of the chamber, and an alternating current in the coil. , A power source for exciting the process gas supplied into the chamber to form a plasma, and a system for flowing a cooling fluid through the tube of the coil.

However, the process apparatus using plasma disclosed in Patent Document 1 has a problem that copper as a coil material is gradually corroded during use.

As a result, there is a problem that process conditions fluctuate and process reproducibility deteriorates. Furthermore, there is a problem that reaction products due to copper corrosion are clogged in the coil in the long term, and the stable operation of the semiconductor manufacturing apparatus is hindered.
Japanese Patent No. 2804879

  The present invention provides a semiconductor manufacturing apparatus that can operate stably for a long period of time.

A semiconductor manufacturing apparatus according to an aspect of the present invention includes a container configured to be capable of reducing the pressure inside, a susceptor that supports a substrate to be processed housed in the container, and a copper tube disposed along the outer wall of the container. A coil, a power source for supplying AC power to the coil, generating plasma in the container, a reject fluid from one end of the coil, and a cooling fluid discharged from the other end of the coil A circulating water system for circulating the cooling fluid in the copper pipe of the coil, and a coating formed on the inner wall of the copper pipe of the coil to prevent corrosion of the coil by the cooling fluid;
It is characterized by comprising.

  According to the present invention, a semiconductor manufacturing apparatus that can operate stably for a long period of time can be obtained.

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

A semiconductor manufacturing apparatus according to an embodiment of the present invention will be described with reference to FIGS. FIG.
Is a sectional view showing a semiconductor manufacturing apparatus, FIG. 2 is a sectional view showing a structure of a coil used in the semiconductor manufacturing apparatus, FIG. 3 is a sectional view showing a process of forming a coating on the inner wall of the coil used in the semiconductor manufacturing apparatus,
FIG. 4 is a diagram showing the relationship between the cumulative number of processes of the semiconductor manufacturing apparatus, the film formation rate, and the in-plane uniformity, in comparison with the comparative example.

In this embodiment, high density plasma chemical vapor deposition (HDP-CVD) is used in which a silicon oxide film is formed on a semiconductor substrate using high density plasma.
It is also an example of a device.

As shown in FIG. 1, the semiconductor manufacturing apparatus 10 of the present embodiment includes a container 11 configured to be capable of reducing the pressure inside, and a susceptor 13 that supports a semiconductor substrate 12 (substrate to be processed) stored in the container 11.
A coil 14 made of a copper tube disposed along the outer wall so as to surround the container 11, a power source 15 for supplying AC power to the coil 14 and generating plasma in the container 11, and one end of the coil 14 The cooling fluid is supplied from the part 14 a, the cooling fluid is discharged from the other end 14 b of the coil 14, and the circulating water system 16 for circulating the cooling fluid in the copper pipe of the coil 14, and the copper pipe of the coil 14 And a coating 17 that is formed on the inner wall and prevents corrosion of the coil 14 by the cooling fluid.

Furthermore, it has a nozzle 18 for introducing process gas into the container 11, a gas supply part 19 for supplying process gas, and an exhaust part 20 for decompressing the container 11.

The container 11 is a processing chamber for forming a film on the semiconductor substrate 12. The container 11 includes an airtight insulating material, for example, a chamber 11a formed by processing ceramics into a dome shape, and a base portion 11b on which the chamber 11a is placed.
By bringing 1b into airtight contact, the inside can be decompressed.

The susceptor 13 is configured to be able to cool the semiconductor substrate 12 by flowing helium (He) gas through a flow path (not shown) provided therein, for example.

The coil 14 is wound in multiple along the outer wall so as to surround the chamber 11a of the container 11, and is fixed to the outer wall. One end 14 a and the other end 14 b of the coil 14 are connected to the power supply 15.

A process gas such as silane (SiH ₄ ) gas and oxygen (O ₂ ) gas is introduced into the container 11 from the gas supply unit 19, and the decompressed state is maintained by the exhaust unit 20.
For example, when high frequency power having a frequency of 13.56 MHz is supplied, plasma is generated in the container 11, the process gas is decomposed and reacted, and a silicon oxide film (SiO _{2) is formed} on the semiconductor substrate 12.
) Is formed.

The circulating water system 16 includes a pump 21 for circulating the cooling fluid and a heat exchanger 22 for cooling the cooling fluid heated by the plasma reaction in order to control the temperature of the inner wall of the chamber 11a. The one end 14a of the coil 14 and the coil 1 are connected via the pipe 23.
4 is connected to the other end 14b.

As shown in FIG. 2, the coil 14 is a copper tube having an outer diameter D1 of 8 mm and an inner diameter D2 of 5 mm, for example, and a coating having a thickness Δd is formed on the inner wall of the copper tube to prevent corrosion of the coil 14 by a cooling fluid. 1
7. For example, gold (Au) which is a noble metal resistant to corrosion is formed.

The coating film 17 is formed by, for example, an electrolytic plating method. That is, as shown in FIG. 3, a copper tube 32 and a gold electrode 33 arranged coaxially inside the copper tube 32 are immersed in a cyan-based gold plating solution 31 stored in a plating tank 30.

Next, the gold electrode 33 is connected to the positive electrode (+) of the power source 34, and the copper tube 32 is connected to the negative electrode (
When connected to (−), gold emits electrons at the gold electrode 33 and is eluted into the gold plating solution 31 as gold ions (Au ²⁺ ).
On the other hand, on the inner wall of the copper tube 32, gold ions (Au ²⁺ ) receive electrons and become gold.
2 deposits on the inner wall. As a result, gold is electrolytically plated on the inner wall of the copper tube 32 to form the coating film 17.

A coil 14 having a coating film 17 formed on the inner wall is obtained by winding a copper tube 32 having a gold plating film formed on the inner wall as the coating film 17 along the outer wall of the chamber 11a.

The thickness Δd of the gold plating is, for example, about 2 to 3 μm. This is because if the thickness of the gold plating is too thin, pinholes remain in the gold plating film and corrosion may progress from the pin pole. Moreover, it is because the manufacturing cost of a gold plating film will increase when it is too thick.

As a result, the copper tube of the coil 14 can be prevented from being corroded by the circulating pure water, so that the process conditions are maintained constant and the semiconductor manufacturing apparatus 10 can be operated stably over a long period of time. It is possible to make it.

As a result, the reproducibility of the deposition rate of the silicon oxide film formed on the semiconductor substrate 12 and the in-plane uniformity of the film thickness can be stably maintained over a long period of time.

FIG. 4 is a diagram showing the relationship between the cumulative number of semiconductor substrates 12 processed by the semiconductor manufacturing apparatus 10 and the deposition rate and in-plane uniformity of the silicon oxide film, in comparison with the comparative example. FIG. In the case of the example, FIG. 4B shows the case of the comparative example.
Here, the comparative example means a semiconductor manufacturing apparatus in which the coating film 17 is not formed on the inner wall of the coil 14.

As shown in FIG. 4, in this embodiment, the cumulative number of processed sheets is 10,000, and the film forming speed is 435 to 43.
It is between about 7 nm / min, and the fluctuation range is maintained at ± 0.23% or less.
The in-plane uniformity of the film thickness is between about 9.5 and 10%, and the fluctuation range is suppressed to ± 2.6% or less.

On the other hand, in the comparative example, the film formation rate gradually decreases to 435 to 425 nm / min according to the cumulative number of processed sheets, and the fluctuation range is ± 1.2%, which is about five times that of the present example.
The in-plane uniformity of film thickness gradually deteriorates to 9.5 to 11.5%, and the fluctuation range is ± 10.5%.
And about four times as large as this embodiment.

Moreover, when the internal diameter D2 of the copper pipe of the coil 14 was measured, it is 5.11 mm-5 in a present Example.
. It was between 10 mm and was almost unchanged from the initial value.
Thereby, the expansion of the inner diameter D2 due to corrosion and ionization of the copper tube of the coil 14 and dissolution into pure water was not recognized.

On the other hand, in the comparative example, the inner diameter D2 of the copper tube of the coil 14 is 5.98 mm, which is the original 5.11.
It increased from 0.8 mm to 0.87 mm.
Thereby, the expansion of the inner diameter D2 due to corrosion and ionization of the copper tube of the coil 14 and dissolution into pure water was recognized.

Furthermore, when the inner wall of the copper tube of the coil 14 was observed with a fiberscope or the like, the gold glossy surface was preserved cleanly in this example.
On the other hand, in the comparative example, many green deposits were found on the inner wall of the copper tube of the coil 14, particularly in the vicinity of the connection portion with the pipe 23.

When green deposits were collected and the components were examined by AES (Auger Electron Spectroscopy), the deposits were copper hydroxide Cu (OH) ₂ formed by bonding dissolved copper ions with hydroxyl groups.
And so-called patina was confirmed.

When copper melts and the inner diameter D2 of the copper tube of the coil 14 increases, the cross-sectional area of the coil 14 decreases, so that the resistance of the coil 14 increases and the high-frequency current hardly flows through the coil 14.
As a result, it was found that the coupling efficiency of high-frequency power was reduced, the process gas decomposition efficiency was lowered, the film formation rate was lowered, and the in-plane uniformity was deteriorated.

As described above, the semiconductor manufacturing apparatus 10 according to the present embodiment uses the copper tube coil 14 having the coating 17 formed on the inner wall, applies a high frequency while circulating pure water through the copper tube, and the semiconductor substrate 1.
A silicon oxide film is formed on 2.

As a result, the inner wall of the copper pipe can be prevented from being corroded by the circulating pure water, so that the process conditions can be maintained constant and the semiconductor manufacturing apparatus 10 can be operated stably over a long period of time. Can do.

Although the case where the coating 17 having corrosion resistance against circulating pure water is a gold plating film has been described here, it is a plating film of platinum, palladium, rhodium or the like, which is a noble metal that is resistant to corrosion like gold. It doesn't matter.

Although the case where the coating film 17 is formed by an electrolytic plating method has been described, it can also be performed by an electroless plating method.
However, since the electroless plating method is generally inferior to the electrolytic plating method in the denseness of the film, the thickness of the plating film is preferably thicker than the electrolytic plating method.

Although the case where the coating film 17 is formed on the inner wall of the copper tube of the coil 14 has been described, it may be formed also on the outer wall of the copper tube of the coil 14.
That is, in FIG. 3, by arranging gold electrodes around the copper tube 32, gold plating can be applied to the inner wall and the outer wall of the copper tube of the coil 14 at a time.

Since the coating 17 is also formed on the outer wall of the copper tube of the coil 14, corrosion of the outer wall of the copper tube due to moisture in the atmosphere can be prevented. There is an advantage that contributes to maintaining the efficiency stably over a long period of time.

Alternatively, after forming the coil 14 by wrapping the copper tube 32 with the gold plating film formed on the inner wall in multiple layers, the outer wall of the copper tube of the coil 14 may be plated with gold.
According to this, in addition to gold, silver (Ag) having a specific resistance smaller than that of copper can be plated on the outer wall of the copper tube of the coil 14.

Although the case where the container 11 of the semiconductor manufacturing apparatus 10 has the dome-shaped chamber 11a has been described, the chamber may be cylindrical or flat.
When the chamber is flat, a spiral coil, a so-called mosquito coil type coil may be used.

Although the case where the semiconductor manufacturing apparatus 10 is an HDP-CVD apparatus has been described, an etching apparatus using plasma may be used.
In the case of the etching apparatus, for example, the reproducibility of the etching rate of the silicon oxide film and the uniformity of the etching rate in the plane can be maintained constant, and the etching apparatus can be stably operated for a long period of time.

For example, a mixed gas of argon (Ar) and fluorocarbon (CF ₄ ) is used as the etching gas. Due to the chemical reaction with the fluorocarbon radical (CF _x ), the semiconductor substrate 1
The silicon oxide film on 2 is etched.
Further, using argon gas as an etching gas, silicon or a silicon oxide film can be etched by sputtering with argon ions.

Sectional drawing which shows the semiconductor manufacturing apparatus based on the Example of this invention. Sectional drawing which shows the structure of the coil used for the semiconductor manufacturing apparatus based on the Example of this invention. Sectional drawing which shows the process of forming a film in the inner wall of the coil used for the semiconductor manufacturing apparatus based on the Example of this invention. FIG. 4A is a diagram showing the relationship between the number of accumulated processes of a semiconductor manufacturing apparatus according to an embodiment of the present invention, the film forming speed, and the in-plane uniformity in comparison with the comparative example, and FIG. FIG. 4B shows a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Semiconductor manufacturing apparatus 11 Container 11a Chamber 11b Base part 12 Semiconductor substrate 13 Susceptor 14 Coil 15 Power supply 16 Circulating water system 17 Coating 18 Nozzle 19 Gas supply part 20 Exhaust part 21 Pump 22 Heat exchanger 23 Pipe 30 Plating tank 31 Gold plating liquid 32 Copper tube 33 Gold electrode 34 Power supply

Claims (5)

A container configured to be able to depressurize the interior;
A susceptor for supporting a substrate to be processed housed in the container;
A coil of copper pipe disposed along the outer wall of the container;
A power source for supplying AC power to the coil and generating plasma in the container;
A circulating water system for supplying a cooling fluid from one end of the coil, discharging the cooling fluid from the other end of the coil, and circulating the cooling fluid in a copper pipe of the coil;
A coating formed on the inner wall of the copper tube of the coil and preventing corrosion of the coil by the cooling fluid;
A semiconductor manufacturing apparatus comprising: The said coating is gold, platinum, palladium, or rhodium.
The semiconductor manufacturing apparatus described in 1. The semiconductor manufacturing apparatus according to claim 2, wherein the coating is a coating formed by an electrolytic plating method.   The semiconductor manufacturing apparatus according to claim 1, wherein the cooling fluid is pure water. The semiconductor manufacturing apparatus according to claim 1, wherein the coating is formed on an outer wall of a copper tube of the coil.

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