JP2005217220A - Device for manufacturing semiconductor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor manufacturing device for fixing a formation speed, and for realizing high speed thick film formation by a remote plasma CVD method or the like. <P>SOLUTION: This semiconductor manufacturing device is configured to carry out any of film formation, etching and surface treatment, by introducing reactive gas 7 to a reaction chamber 8 and bringing it into contact with a substrate 9a. The reaction device is constituted of an excitation chamber 6 and the reaction chamber 8, and the ejection of the reactive gas is carried out from at least a main exhaust port 10 installed in the reaction chamber 8 and an auxiliary exhaust port 3b installed in the excitation chamber 3 as well. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a semiconductor manufacturing apparatus for forming a semiconductor element or the like.

  In recent years, research on forming a silicon thin film on a non-conductive dissimilar substrate such as a glass substrate has been actively conducted. The silicon thin film formed on this glass substrate can be used for a wide range of applications, such as TFTs for liquid crystal devices (Thin Film Transistors), thin film photovoltaic devices, and the like.

  The thin-film photovoltaic power generation element is intended to reduce the cost by forming a silicon thin film on an inexpensive substrate by a low-temperature process and using it for a photoelectric conversion device. As the silicon thin film, use of not only amorphous silicon but also crystalline silicon has been studied. The thin-film photovoltaic power generation element using crystalline silicon is not observed with the light degradation which is a problem in the thin-film photovoltaic power generation element using amorphous silicon, and the thin-film photovoltaic power generation element using amorphous silicon. Then, insensitive long wavelength light can be converted into electrical energy. This technology is expected to be applicable not only to thin-film photovoltaic elements but also to photoelectric conversion elements such as optical sensors.

  In general, a plasma CVD method is used to form these silicon (non-single crystal silicon) thin films. It is known that amorphous or crystalline silicon can be formed on a substrate at a low temperature by this method, and it is said that it is effective for cost reduction.

  High-speed film formation is effective for improving production efficiency, but the commonly used counter electrode type plasma CVD method enables high-speed film formation by increasing the input power. However, when the input power is increased, in the counter electrode type plasma CVD apparatus in which the electrode is in the reaction chamber, the film quality called plasma damage is inevitably deteriorated.

Therefore, a remote plasma CVD method, which is a kind of plasma CVD method capable of separating an electrode from a reaction chamber, is applied to non-single crystal silicon thin film formation (see, for example, Patent Documents 1 and 2). In this method, a carrier gas such as argon is excited in an excitation chamber and introduced into a lower reaction chamber to activate a reactive gas and form a film on a substrate. The reactive gas after treatment is exhausted from below the reaction chamber by an exhaust pump.
JP-A-5-166755 JP-A-11-233491

  According to the above remote plasma CVD method, for example, argon was used as a carrier gas, and monosilane was used as a reaction gas, so that high-speed film formation at a film formation rate of 2 nm / s was achieved. Naturally, a high quality film free from plasma damage was obtained. Further, the amount of hydrogen in the film is about 5%, and there is an advantage that crystallization is easy by laser irradiation.

  However, in the conventional remote plasma CVD method, when a relatively thick film having a thickness of about 2 μm is formed for manufacturing a solar cell, a problem that the film formation speed decreases as the film formation proceeds. That is, in the case of a conventional remote plasma CVD apparatus, when forming a thick film, the forming speed gradually decreases, so that high-speed film formation cannot be performed and it is difficult to control the film thickness.

  Accordingly, an object of the present invention is to provide a semiconductor manufacturing apparatus capable of solving the above-described problems and forming a thick film at a constant forming speed and at a high speed by a remote plasma CVD method or the like.

  In order to achieve the above object, the present invention is configured as follows.

  According to a first aspect of the present invention, there is provided a semiconductor manufacturing apparatus in which a reactive gas is introduced into a reaction chamber and excited to contact a sample to perform any one of film formation, etching, and surface treatment. It comprises a reaction chamber, and the reactive gas is exhausted from at least two exhaust ports provided in the excitation chamber and the reaction chamber.

  The invention according to claim 2 is the semiconductor manufacturing apparatus according to claim 1, wherein the reactive gas excitation source is not the counter electrode type but the external excitation type, the carrier gas is discharged in the excitation chamber, and the reaction is performed in the reaction chamber. In an apparatus for activating a reactive gas and performing a necessary reaction, the two exhaust ports are provided in the excitation chamber and the reaction chamber, respectively.

  According to a third aspect of the present invention, in the semiconductor manufacturing apparatus according to the second aspect, the exhaust amount from the exhaust port provided in the excitation chamber is smaller than the exhaust amount from the exhaust port provided in another reaction chamber. Features.

  According to a fourth aspect of the present invention, in the semiconductor manufacturing apparatus according to the second aspect, the exhaust port provided in the excitation chamber has a mechanism capable of controlling the exhaust amount.

  According to a fifth aspect of the present invention, in the semiconductor manufacturing apparatus according to any one of the second to fourth aspects, the reactive gas has a hydrogen atom in any of them.

  According to a sixth aspect of the present invention, in the semiconductor manufacturing apparatus according to any one of the second to fourth aspects, the carrier gas does not contain a hydrogen atom, and the reactive gas contains a hydrogen atom.

  A seventh aspect of the present invention is the semiconductor manufacturing apparatus according to any one of the second to sixth aspects, wherein the reactive gas is a material system that forms a thin film on a substrate.

  The invention according to claim 8 is the semiconductor manufacturing apparatus according to claim 7, wherein the reactive gas is a material system for forming a silicon-based thin film on the substrate.

The invention according to claim 9 is the semiconductor manufacturing apparatus according to claim 6, wherein the reactive gas is a material system mainly composed of monosilane, and the carrier gas is any one of Ar, Ne, He, and N _2. It consists of an active gas.

<Key points of the invention>
The silicon film is usually formed by decomposing monosilane or disilane, and at this time, two molecules or more of hydrogen are released. However, since this has a lower specific gravity than argon, it is usually installed at the top of the reaction chamber and gradually accumulates in the excitation chamber. Accordingly, the plasma state in the excitation chamber changes with time. In particular, in an apparatus designed to maintain a stable discharge with argon gas, it becomes difficult to maintain the discharge when the proportion of a gas having completely different plasma states such as hydrogen increases. Since the film formation speed of 2 nm / s is obtained at the initial stage of film formation, the film formation speed is kept constant by adding a function for maintaining the gas composition at that time to the apparatus. It is thought that it can be kept. That is, a high-quality thin film can be formed at a high speed by keeping the composition of the reactive gas species at the time of film formation constant.

  According to the present invention, an auxiliary exhaust port is provided on the excitation chamber side separately from the main exhaust port on the reaction chamber side, and from the auxiliary exhaust port, for example, when the silicon film is formed, the gas gradually accumulates on the upper portion of the excitation chamber. As a result, the silicon film can be formed without substantially changing the gas composition in the excitation chamber and without reducing the film formation rate.

  Therefore, according to the semiconductor manufacturing apparatus of the present invention, for example, a thick silicon film for manufacturing a solar cell can be easily controlled with a constant film formation speed without causing a decrease in film formation speed. It can be formed at high speed.

  Hereinafter, the present invention will be described based on the illustrated embodiments.

  FIG. 1 shows a configuration of a semiconductor manufacturing apparatus according to an embodiment of the present invention. This semiconductor manufacturing apparatus includes a cylindrical excitation chamber 3 that excites a reactive gas introduced therein into plasma, and a reaction chamber (process) provided below the excitation chamber and in communication with the excitation chamber 3. Room) 8.

  The excitation chamber 3 has a tubular shape with a length of about 40 cm, and is provided with an inlet 3a for the carrier gas 1 in the upper part thereof. The excitation chamber 3 is provided with a high-frequency introduction section (waveguide) 3C at the center of the excitation chamber 3 at a distance of 20 cm from the boundary with the reaction chamber and the tube end of the carrier gas introduction position. In this configuration, a microwave of 2.45 GHz is introduced from the microwave power source 5 through the matching device 4.

  The reaction chamber 8 is connected to a supply pipe for a reactive gas (reactive gas) 7 used for etching or ashing. A substrate holder 9 is provided inside the reaction chamber 8, and the reaction gas 7 is guided to a substrate (sample) 9 a that is an object to be processed supported by the substrate holder 9. Then, the gas that has passed through the periphery of the substrate holder 9 is discharged from the main exhaust port 10 provided below the reaction chamber 8 to an exhaust device by an exhaust pump (not shown).

  An auxiliary exhaust port 3b is provided in the upper part of the excitation chamber 3, and hydrogen gradually accumulated in the upper part of the excitation chamber 3 is exhausted from the auxiliary exhaust port 3b so that the gas composition becomes constant during film formation. It is configured. The auxiliary exhaust port 3b provided in the excitation chamber 3 is provided with a valve mechanism capable of controlling the exhaust amount.

  In short, the semiconductor manufacturing apparatus of FIG. 1 introduces a reaction gas (reactive gas) 7 into the reaction chamber 8 and excites it to contact the substrate 19 as a sample to perform any one of film formation, etching, and surface treatment. The reaction apparatus includes an excitation chamber 6 and a reaction chamber 8, and the reactive gas is exhausted at least in addition to the main exhaust port 10 provided in the reaction chamber 8, and the auxiliary exhaust port 3 b provided in the excitation chamber 3. It is configured to be performed from.

  Next, the operation of this semiconductor manufacturing apparatus will be described by taking the case of film formation as an example.

  As described above, the semiconductor manufacturing apparatus of the present invention is mainly characterized in that an auxiliary exhaust port is provided in the excitation chamber for exciting the carrier gas so that the gas composition is constant during film formation. .

  In the remote plasma CVD method, a carrier gas is excited in an excitation chamber, and this is introduced into a reaction chamber directly below according to the flow of gas exhaust, and the reaction gas species introduced into the reaction chamber are activated to form a film. After that, the gas is discharged from the exhaust port at the bottom of the substrate. Therefore, conventionally, a change in the gas composition of the excitation chamber has been unavoidable in a situation where a reactive gas species is decomposed and a light gas such as hydrogen is generated. Initially, it was thought that due to gas diffusion, the gas composition was the same as that in the reaction chamber and uniform in the excitation chamber, particularly near the discharge section.

  However, when the present inventors observed the film deposition state on the discharge tube during film formation in the reaction chamber, the film deposition was observed only in about 5 cm in the excitation chamber 3 in the portion directly connected to the reaction chamber 8. There wasn't. The excitation chamber 3 has a tubular shape with a length of about 40 cm, and the discharge portion is located at the center, at the boundary with the reaction chamber, and at an equidistant position of 20 cm from the tube end of the carrier gas introduction position. Therefore, it is considered that the discharge is maintained only by the carrier gas. However, it is considered that hydrogen gradually accumulates in the upper part of the excitation chamber 3 as the reaction proceeds.

  Therefore, an auxiliary exhaust port 3b is provided in the upper part of the excitation chamber 3 and in the vicinity of the carrier gas introduction part. This makes it possible to form a film without causing a substantial change in the gas composition in the excitation chamber 3 and without reducing the film formation rate. Of course, if the exhaust from the auxiliary exhaust port 3b is performed in the same manner as the exhaust from the main exhaust port 10 on the reaction chamber 8 side, the effective use of the introduced carrier gas is hindered, so it is necessary to stop it in an auxiliary role. There is.

Such stabilization of the film forming speed is not only when forming a silicon thin film, but also when Ar and NH ₃ are introduced from the carrier gas inlet 3a and SiH ₄ is introduced into the reaction chamber 8 to form a SiN film. It was the same.

The same effect was obtained when SiO ₂ was formed using NO ₂ instead of NH ₃ .

The same reaction is exactly the same when an amorphous or crystalline carbon thin film is formed using carbon hydride (CH ₄ , C ₂ H ₆ , C ₂ H ₄ , C ₂ H ₂ ). It was.

  The above phenomenon is not limited to the remote plasma CVD method. When an asymmetrical discharge method is used instead of the normal counter electrode type CVD method such as discharge from the counter electrode from the outside of the reaction chamber or catalytic CVD method. It is valid. The same phenomenon is considered to occur in the ordinary counter electrode type CVD method, but the above phenomenon is considered not to be significant due to the influence of the electrode arrangement in the reaction chamber and the gas flow direction.

  The same effect should be observed in dry etching, but in this case, the specific gravity of the generated species is often close to that of the introduced reactive species, and no particularly significant difference was observed.

  Examples of the present invention will be described. In addition, the following Examples show an example of this invention and this invention is not limited to these.

[Example 1]
In this example, an amorphous silicon film was deposited using Ar as a carrier gas and SiH ₄ as a reaction gas. In FIG. 1, Ar was introduced into the excitation chamber 3 at 100 sccm as the carrier gas 1. The excitation chamber 3 is made of a quartz tube having a diameter of 5 cm and a length of 40 cm.

  An auxiliary exhaust port 3b for performing the auxiliary exhaust 2 is provided in the vicinity of the carrier gas introduction port 3a above the excitation chamber 3.

  Further, a high-frequency introducing portion (waveguide) 3c was provided at a position 20 cm from the carrier gas introducing port, and a discharge was generated from the 2.45 GHz microwave power source 5 via the matching device 4. The generated plasma forms a plasma region 6 according to the flow of the carrier gas and spreads to the reaction chamber 8.

SiH ₄ was introduced into the reaction chamber 8 as a reaction gas 7 at 20 sccm, and an amorphous silicon film was formed on the glass substrate 9 a on the substrate holder 9 maintained at 250 ° C. The pressure in the reaction chamber 8 was 20 Pa. The gas that has passed through the periphery of the substrate holder 9 is discharged from the lower main exhaust port 10 to a normal exhaust device.

  Here, the film forming speed with the auxiliary exhaust 2 closed is shown by a curve A in FIG. When the film thickness was evaluated, the film formation did not progress in about 8 minutes.

  On the other hand, the auxiliary exhaust port 3b of the auxiliary exhaust 2 was slightly opened to form a film so that the exhaust amount was 1/10 of the exhaust amount from the lower exhaust port 10. As a result, as shown by a curve B in FIG. 2, the initial film formation rate was slightly reduced, but a linear film formation rate was obtained.

Since the decomposition efficiency of SiH ₄ is not clear, the amount of generated hydrogen molecules is not clear, but if the decomposition efficiency is 50%, 200 cc of hydrogen is generated in 10 minutes. This is 1/2 of the volume of the excitation chamber 3 and is an amount that can be sufficiently affected. On the other hand, 1/10 of the total auxiliary exhaust was sufficient to prevent accumulation of hydrogen gas. Incidentally, the optical and electrical characteristics of the formed amorphous silicon film were exactly the same as those without the auxiliary exhaust.

[Example 2]
In this embodiment, in FIG. 1, when Ar is used as a carrier gas 1 and SiH ₄ is used as a reaction gas 7 and an amorphous silicon film is deposited, an RF power source of 13.56 MHz is used instead of the microwave power source 5. It was. However, unlike FIG. 1, a waveguide was not used, and the excitation chamber was directly sandwiched between electrodes for discharge.

  The generated plasma forms a plasma region 6 according to the flow of the carrier gas 1 and spreads to the reaction chamber 8 in the same manner as in the case of discharging with microwaves. The flow rates of the carrier gas 1 and the reaction gas 7 were the same as in Example 1, and the pressure in the reaction chamber 8 was 50 Pa.

  On the other hand, the auxiliary exhaust port 3b of the auxiliary exhaust 2 was slightly opened so that the exhaust amount was 1/10 of the exhaust amount from the lower main exhaust port 10, and film formation was performed. As a result, the initial film formation rate was slightly reduced, but a linear film formation rate was obtained.

  On the other hand, even when the auxiliary exhaust 2 was closed, the film formation rate was not significantly reduced.

  In addition, a decrease in film formation rate was observed after 30 minutes of film formation. This is considered because the decomposition efficiency of the carrier gas at a low frequency is low.

  The device was effective even when using a discharge at a low frequency of 100 kHz.

[Example 3]
In this embodiment, as shown in FIG. 3, an apparatus configuration in which a heating wire 14 for reaction gas decomposition is provided in an excitation chamber 13, and SiH ₄ , PH ₃ , Ar and H ₂ are used as reaction gases and doped amorphous is used. A silicon film was deposited.

In FIG. 3, SiH ₄ was introduced into the excitation chamber 13 as a reaction gas 11 at 100 sccm, PH ₃ (0.1% in H ₂ ) at 10 sccm, H ₂ at 20 sccm, and Ar at 30 sccm. A reaction gas introduction part 13a is provided in the upper part of the excitation chamber 13 and an auxiliary exhaust port 13b for performing the auxiliary exhaust 12 in the vicinity thereof. A heating wire 14 for reaction gas decomposition was provided in the excitation chamber 13 and heated to 1800 ° C.

  The generated active species form an activated region 15 according to the gas flow and spread to the reaction chamber 16. A crystalline silicon film was formed on the glass substrate 19 on the substrate holder 17 held at 400 ° C. in the reaction chamber 16. The reaction chamber pressure was 1 Pa. The gas that has passed around the substrate holder is discharged from the lower main exhaust port 18 to a normal exhaust device.

The opening of the auxiliary exhaust port 13b of the auxiliary exhaust 12 was opened so as to be 1/5 of the exhaust amount from the lower main exhaust port 18, and film formation was performed. As a result, a linear deposition rate was obtained. In the apparatus of this example, since the decomposition efficiency of SiH ₄ was high, it was very effective to make the reaction gas composition constant by auxiliary exhaust.

[Example 4]
In this example, an amorphous silicon nitride film was deposited using Ar and NH ₃ as a carrier gas and SiH ₄ as a reaction gas. The same apparatus as in Example 1 was used for deposition.

In FIG. 1, 20 sccm of Ar and 20 sccm of NH ₃ were introduced into the excitation chamber 3 as the carrier gas 1. An auxiliary exhaust port 3b for performing auxiliary exhaust 2 is provided in the vicinity of the carrier gas introduction port 3a.

A discharge was generated from the 2.45 GHz microwave power source 5 via the matching device 4. The generated plasma forms a plasma region 6 according to the flow of the carrier gas and spreads to the reaction chamber 8. SiH ₄ was introduced as a reaction gas 7 into the reaction chamber 8 at 5 sccm, and an amorphous silicon nitride film was formed on the glass substrate 9 a on the substrate holder 9 held at 250 ° C. The reaction chamber pressure was 20 Pa.

  The gas that has passed around the substrate holder is discharged from the lower main exhaust port 10 to a normal exhaust device. Film formation was performed by slightly opening the opening of the auxiliary exhaust port 3b of the auxiliary exhaust 2 so that the exhaust amount from the lower main exhaust port 10 was 1/10. As a result, the initial film formation rate was slightly reduced, but a linear film formation rate was obtained.

In the above embodiments, doping is shown for n-type using PH ₃ , but this method can be similarly used for other dopants or p-type. Alternatively, an alloy film containing other elements, hydrogen, oxygen, carbon, germanium, or the like in the film may be used.

  Further, in the crystallization of silicon such as Ni and Cr, the presence of an element having a catalytic action does not hinder the effect of the present invention.

  Further, as a semiconductor material, the same group IV materials such as carbon and germanium, III-V group compounds based on GaAs and InP, and II-VI group compounds such as CdTe have the same film formation mechanism. Can be used.

  Further, although no effect was observed in dry etching, it is clear that the effect is expected when a large amount of hydrogen is generated by the reaction. Furthermore, also in the active hydrogen treatment using hydrogen diluted with another gas, a result that a certain effect for a long time can be obtained by applying the present invention was obtained.

It is a cross-sectional schematic diagram of the semiconductor manufacturing apparatus in Example 1 of this invention. It is a figure which shows the relationship between the film-forming time and film thickness in Example 1 of this invention. It is a cross-sectional schematic diagram of the semiconductor manufacturing apparatus in Example 3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Carrier gas 2 Auxiliary exhaust 3 Excitation chamber 3a Carrier gas introduction port 3b Auxiliary exhaust port 3c High frequency introduction part 4 Matching device 5 Microwave power source 6 Plasma region 7 Reactive gas 8 Reaction chamber 9 Substrate holder 9a Substrate 10 Main exhaust port 19 Glass substrate

Claims (9)

In an apparatus that introduces a reactive gas into a reaction chamber, excites it, contacts the sample, and performs any of film formation, etching, and surface treatment.
A semiconductor manufacturing apparatus characterized in that a reaction apparatus includes an excitation chamber and a reaction chamber, and the reactive gas is exhausted from at least two exhaust ports provided in the excitation chamber and the reaction chamber. 2. The semiconductor manufacturing apparatus according to claim 1, wherein a reactive gas excitation source is not a counter electrode type but an external excitation type, a carrier gas is discharged in the excitation chamber, and the reactive gas is activated in the reaction chamber. In the apparatus for performing the reaction,
The semiconductor manufacturing apparatus, wherein the two exhaust ports are provided in the excitation chamber and the reaction chamber, respectively. The semiconductor manufacturing apparatus according to claim 2,
A semiconductor manufacturing apparatus, wherein an exhaust amount from an exhaust port provided in the excitation chamber is smaller than an exhaust amount from an exhaust port provided in another reaction chamber. The semiconductor manufacturing apparatus according to claim 2,
A semiconductor manufacturing apparatus, wherein an exhaust port provided in the excitation chamber has a mechanism capable of controlling an exhaust amount thereof. The semiconductor manufacturing apparatus according to any one of claims 2 to 4,
A semiconductor manufacturing apparatus, wherein the reactive gas has a hydrogen atom in any of them. The semiconductor manufacturing apparatus according to any one of claims 2 to 4,
The semiconductor manufacturing apparatus, wherein the carrier gas does not contain a hydrogen atom, and the reactive gas contains a hydrogen atom. The semiconductor manufacturing apparatus according to any one of claims 2 to 6,
A semiconductor manufacturing apparatus, wherein the reactive gas is a material system for forming a thin film on a substrate. The semiconductor manufacturing apparatus according to claim 7.
A semiconductor manufacturing apparatus characterized in that the reactive gas is a material system for forming a silicon-based thin film on a substrate. The semiconductor manufacturing apparatus according to claim 6,
A semiconductor manufacturing apparatus, wherein the reactive gas is a material system mainly composed of monosilane, and the carrier gas is an inert gas of Ar, Ne, He, or N ₂ .

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