JP2001168033A - Semiconductor manufacturing equipment - Google Patents

Abstract

(57) An object of the present invention is to provide a semiconductor manufacturing apparatus capable of preventing a reaction product deposited in a sub-chamber for generating plasma of a cleaning gas from flowing into a main chamber. A bypass passage (18) is provided between an introduction passage (3) and a vacuum exhaust passage (4) communicating between a main chamber (1) and a sub-chamber (2).
8 is provided at the connection point with the main chamber 1, the main chamber 1 and the sub-chamber 2 are communicated when the main chamber 1 is cleaned, and when the sub-chamber 2 is evacuated, the 3-port valve 17 is switched to switch the bypass passage. The sub-chamber 2 is connected to the evacuation passage 4 via 18. This can prevent particles from flowing from the sub chamber 2 to the main chamber 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a semiconductor manufacturing apparatus, and more particularly, to a semiconductor manufacturing apparatus having a dry cleaning function in a chamber.

[0002]

2. Description of the Related Art In recent semiconductor device manufacturing processes, a CVD (Chemical Vapor Deposit) method is used to form a film on a semiconductor substrate surface.
ion) method is essential. As is well known, the CVD method supplies one or several kinds of compound gas composed of elements constituting a thin film material and a single gas onto a semiconductor substrate in a film formation chamber and performs a chemical reaction on a gas phase or a surface of the semiconductor substrate. This is a method for forming a desired thin film. The CVD method includes a thermal CVD method using heat as excitation energy of a CVD reaction, a plasma CVD method in which a thin film is formed by plasma discharge decomposition of a reactive gas (raw material gas), and a method in which gas molecules are decomposed by light energy to form a thin film. For example, there is a photo-CVD method.

Here, as the semiconductor substrate is formed, a thin film material adheres and deposits on the inner wall of the chamber where the film is formed. The thickness of the deposited film increases according to the number of processed semiconductor substrates. If this peels off partially and adheres to the semiconductor substrate, it causes a pattern defect of the device. In order to prevent this, it is necessary to periodically remove these deposited films.

[0004] As a method of removing the deposited film adhered to the inner wall surface of the chamber, generally, a wet cleaning method of wiping the inside of the chamber with a solvent, or a plasma of a cleaning gas is generated, and the deposited film is formed by using radicals in the plasma. There is a dry cleaning method to remove. In the former case, it is necessary to open the chamber to the atmosphere to perform the operation. Therefore, it takes a long time to start up the apparatus due to evacuation after the operation, which causes a problem in that the operation rate of the apparatus is reduced. For this reason, the latter method is becoming mainstream at present.
Various techniques have been proposed, such as the disclosure example of No. 61623.

FIG. 5 shows an outline of a conventional plasma CVD apparatus having a dry cleaning function in a chamber.
The main chamber 1 houses a semiconductor substrate (not shown) therein,
The source gas supplied from the top nozzle 9 and the side nozzles 10 is turned into plasma by a plasma generation mechanism (not shown) to form a thin film of the source gas on the surface of the semiconductor substrate as is known. At this time, the thin film material adheres and deposits on a place other than the semiconductor substrate such as the inner wall surface of the main chamber 1 and the substrate holding portion (pedestal) 8. Subchamber 2 is main chamber 1
This is used in a dry cleaning process for removing deposits in the inside, and details thereof are shown in FIG.

Referring to FIG. 4, main body 2 through which cooling water circulates
A quartz tube 22 and a sapphire tube 23 are provided inside 1, and NF ₃ gas supplied into the sapphire tube 23 on the inner peripheral side is converted by a microwave 28 supplied from a magnetron 26 via a waveguide 27. When excited, it is turned into plasma to generate fluorine radicals (F radicals). The fluorine radicals are introduced into the main chamber 1 through the introduction passage 3 and react with the deposits in the main chamber 1 to become compounds having a high vapor pressure. As a result, the fluorine radicals are evacuated and removed from the main chamber 1. You.

During the dry cleaning of the main chamber 1, referring to FIG. 5, the first valve 11 and the pressure regulating valve 1
The exhaust gas is evacuated by the dry pump 5 through the vacuum exhaust passage 4 provided with the vacuum pump 3, and the pressure in the main chamber 1 is adjusted to the optimum pressure for dry cleaning by the pressure adjusting valve 13. In the drawing, reference numeral 6 denotes a turbo molecular pump that operates when the main chamber 1 is evacuated, 7 denotes a gate valve, 1
Reference numeral 2 denotes a second valve for communicating / blocking between the discharge port of the turbo molecular pump 6 and the dry pump 5, and reference numeral 14 denotes a throttle valve.

[0008]

The problem here is that since the gas contact portion in the sub-chamber 2 is the sapphire tube 23, the inner wall surface of the sapphire tube 23 contains a reaction containing F and Al (aluminum). A substance is generated, which is separated from the inner wall surface of the sapphire tube 23 when the sub-chamber 2 is evacuated and replaced with Ar (argon) gas, and flows into the main chamber 1 as a result.
This means that it adheres to the inner wall surface of the main chamber 1, the substrate holding unit 8, and further to the semiconductor substrate on which a film is to be formed, thereby causing a device failure. The sapphire tube 23 is originally disposed to protect the quartz tube 23 from the impact of plasma, but the above-described problem cannot be avoided in the conventional apparatus configuration.

The present invention has been made in view of the above problems, and has as its object to provide a semiconductor manufacturing apparatus capable of preventing plasma reaction products deposited in a sub chamber from flowing into a main chamber.

[0010]

In order to solve the above problems, the present invention provides a bypass passage which bypasses a main chamber between an introduction passage and a vacuum exhaust passage, and connects the introduction passage and the bypass passage. At this point, a flow path switching means for selectively taking a first state in which the sub-chamber is communicated with the main chamber and a second state in which the sub-chamber is communicated with the evacuation passage via the bypass passage are provided. Provided. A three-port valve can be used as the passage switching means. When cleaning the main chamber, the flow path switching means is set to the first state, and radicals in the plasma generated in the sub chamber are supplied into the main chamber to obtain a dry cleaning action. At the time of gas replacement, the flow path switching means is set to the second state to evacuate the sub-chamber through the bypass passage, thereby preventing the reaction products attached to the sub-chamber from flowing into the main chamber.

[0011]

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

FIG. 1 shows an embodiment of the present invention.
In this embodiment, a plasma CVD apparatus having a dry cleaning function in a chamber will be described as an example of a semiconductor manufacturing apparatus. Here, portions corresponding to those of the conventional plasma CVD apparatus described with reference to FIG. 5 are denoted by the same reference numerals, and detailed description thereof will be omitted.
That is, in the plasma CVD apparatus according to the present embodiment, the configurations of main chamber 1 and sub-chamber 2 are exactly the same as those in the related art.

In the present embodiment, an inlet passage 3 communicating between the main chamber 1 and the sub-chamber 2 and an evacuation passage 4 connecting the main chamber 1 to a dry pump 5 as evacuation means. , A bypass passage 18 that bypasses the main chamber 1 is provided. A three-port valve 17 is provided at a connection point between the bypass passage 18 and the introduction passage 3.
The connection point between the bypass passage 18 and the vacuum exhaust passage 4 is located on the upstream side when viewed from the exhaust direction with respect to the pressure regulating valve, that is, a pipe portion between the first valve 11 and the pressure regulating valve 13.

The three-port valve 17 is arranged as a flow path switching means according to the present invention, and a first state in which the main chamber 1 and the sub-chamber 2 are communicated with each other and a vacuum in the sub-chamber 2 through the bypass passage 18. The second state connected to the exhaust passage 4 can be selectively taken.

This embodiment is constructed as described above. Next, this operation will be described with reference to FIGS.

(Step S1, t0 to t1) At the time of film formation, the semiconductor substrate is placed on the substrate holding portion 8, and a thin film forming gas supplied from the top nozzle 9 and the side nozzle 10 is supplied to a plasma (not shown) in a known manner. Plasma is generated by a generation mechanism to form a thin film on the surface of the semiconductor substrate. At this time, the first valve 11 is closed, the second valve 12 is open, the gate valve 7 is open, the three-port valve 17 is in the first state, and the inside of the main chamber 1 is set to a predetermined degree of vacuum by the turbo molecular pump 6. Has been exhausted.

The dry cleaning in the main chamber 1 is performed as follows.
This is performed every time a predetermined number of semiconductor substrates are processed. Less than,
The dry cleaning step will be described.

(Step S2, t1 to t2) Dry cleaning is performed after the semiconductor substrate is carried out of the main chamber 1. Then, the first valve 11 is opened, and the second valve 1 is opened.
2 and the gate valve 7 are closed, the flow rate of NF ₃ gas as a cleaning gas is adjusted by the mass flow controller 15 and introduced into the sub-chamber 2, and the microwave 28 from the magnetron 26 is applied to convert the NF ₃ gas into plasma. (See FIG. 4). F radicals in the plasma are introduced into the passage 3
Through the three-port valve 17 in the first state into the main chamber 1. The introduced F radicals react with a deposit (for example, a silicon oxide film (SiO ₂ )) to be removed to become a compound having a high vapor pressure, and are evacuated through the evacuation passage 4 to be evacuated from the main chamber 1. Removed. During this dry cleaning step, the pressure inside the main chamber 1 is maintained at an optimum pressure for dry cleaning by the pressure regulating valve 13.

(Step S3, t2 to t3) Immediately before the end of the dry cleaning, the three-port valve 17 is switched from the first state to the second state. Thereby, the main chamber 1
The introduction of the F radical into the inside is stopped, and the NF ₃ gas is evacuated through the bypass passage 18. At this time, the connection point between the bypass passage 17 and the vacuum exhaust passage 4 is located on the upstream side as viewed from the exhaust direction with respect to the pressure regulating valve 13, so that the pressure fluctuation of the dry cleaning due to the change of the gas flow path is suppressed. Separation of the reaction product of F and Al in the sub-chamber 2 is suppressed. Further, since the three-port valve 17 is switched from the first state to the second state immediately before the end of the dry cleaning, the reaction product peeled off by the pressure change immediately after the end is introduced into the main chamber 1. Inflow is prevented.

(Step S4, t3 to t4) Next, the first
The valve 11 is closed, and in response to this operation, the supply of the NF ₃ gas is stopped. Then, the opening of the pressure adjusting valve 13 is fully opened, and the evacuation of the inside of the sub-chamber 2 is performed via the bypass passage 18.

(Step S5, t4 to t5) After the evacuation of the sub-chamber 2 is performed, the Ar gas whose flow rate is adjusted by the mass flow controller 16 is supplied into the sub-chamber 2, and the NF ₃ in the sub-chamber 2 is supplied. Replace the gas.

(Step S6, t5 to t6) Thereafter, A
The supply of the r gas is stopped, and the inside of the sub-chamber 2 is evacuated again.

During the evacuation of the sub-chamber 2 and the replacement of the Ar gas, there is a possibility that the reaction products are separated in the sub-chamber 2, but these dusts are evacuated through the bypass passage 18. So the main chamber 1
It does not flow into.

(Step S7, t6-t7) Next, the first
The evacuation of the main chamber 1 is started by opening the valve 11, and when the pressure is reduced to a certain time or pressure, the three-port valve 17 is switched from the second state to the first state.

(Step S8, t7-t8) Then, the main chamber 1 is replaced by flowing Ar gas for a predetermined time.

(Step S9, t8 to t9) Thereafter, A
The supply of the r gas is stopped, and the main chamber 1 is evacuated to a predetermined pressure.

Next, a state in which a film is formed (step S1)
In order to switch the main chamber 1, the second valve 12 and the gate valve 7 are opened, and the evacuation of the main chamber 1 from the turbo molecular pump 6 side is started. Thereafter, this operation is repeated.

As described above, according to the present embodiment, since the gas path for evacuation in the sub-chamber 2 and the gas replacement in the sub-chamber 2 does not pass through the inside of the main chamber 1, the dry cleaning The reaction product in the sub-chamber 2 can be prevented from flowing into the main chamber 1. When the main chamber 1 is evacuated, the sub-chamber 2
The inside is evacuated at the same time. However, since the evacuation is performed from a relatively low degree of vacuum, the reaction products in the sub-chamber 2 hardly peel and flow into the main chamber 1.

Therefore, it is possible to reduce particles adhering to the inner wall surface of the main chamber 1, the semiconductor substrate, the substrate holding portion 8 and the like during the film formation, thereby suppressing the occurrence of device failure, stabilizing the film thickness, and the like. It is possible to obtain effects such as stabilization of the substrate temperature by stabilizing the contact state between the semiconductor substrate and the substrate holding unit 8 and further improvement of the transfer accuracy of the semiconductor substrate to the substrate holding unit 8.

Although the embodiment of the present invention has been described above, the present invention is, of course, not limited to this, and various modifications can be made based on the technical idea of the present invention.

For example, in the above-described embodiment, a plasma CVD apparatus has been described as an example of the main chamber 1, but the present invention can be applied to a reduced pressure CVD apparatus instead. Further, the present invention is not limited to a film forming apparatus, and can be applied as a plasma etching apparatus or an ashing apparatus.

Further, the radical element for cleaning is not limited to fluorine, and it is also possible to apply another radical element such as a chlorine radical depending on the type of the deposit to be removed.

[0033]

As described above, according to the semiconductor manufacturing apparatus of the present invention, it is possible to prevent particles from flowing from the sub-chamber into the main chamber, thereby suppressing the occurrence of device defects. In addition, effects such as stabilization of film thickness control on the semiconductor substrate, stabilization of the substrate temperature by stabilization of the contact state between the semiconductor substrate and the substrate holding portion, and improvement of the transfer accuracy of the semiconductor substrate can be obtained.

According to the second aspect of the present invention, the gas flow path can be changed without greatly changing the dry cleaning pressure, whereby the separation of the reaction product in the sub-chamber can be suppressed. .

Further, according to the third aspect of the invention, it is possible to prevent particles from flowing from the sub-chamber to the main chamber due to pressure fluctuation immediately after the end of dry cleaning.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a piping configuration and an apparatus configuration of a semiconductor device manufacturing apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating an operation of the exemplary embodiment of the present invention.

FIG. 3 is a diagram for explaining the operation of the embodiment of the present invention, showing a schematic transition of the pressure in each chamber, a switching timing of each valve, and a gas supply timing.

FIG. 4 is a sectional view showing a configuration of a sub chamber.

FIG. 5 is a sectional view showing a piping configuration and a device configuration of a conventional semiconductor device manufacturing apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Main chamber, 2 ... Subchamber, 3 ... Introductory path, 4 ...
Exhaust passage, 5: dry pump, 6: turbo molecular pump,
11: first valve, 12: second valve, 13: pressure regulating valve, 17: 3-port valve (flow path switching means), 18: bypass passage, 23: sapphire tube.

Claims (3)

[Claims] 1. A main chamber for performing a predetermined process on a surface of a semiconductor substrate, a sub-chamber for generating a plasma of a cleaning gas for removing deposits in the main chamber, and a sub-chamber for the main chamber and the sub-chamber. A semiconductor manufacturing apparatus comprising: an introduction passage that communicates between the two and introduces radicals in the plasma into the main chamber; and a vacuum exhaust passage that connects the inside of the main chamber to a vacuum exhaust unit through a pressure regulating valve. A bypass passage that bypasses the main chamber is provided between the introduction passage and the evacuation passage, and a connection point between the introduction passage and the bypass passage communicates between the sub-chamber and the main chamber. 1 and a second state in which the sub-chamber and the evacuation passage communicate with each other via the bypass passage. Wherein the channel switching means is in the first state when the main chamber is being cleaned, and the channel switching means is in the second state when the sub-chamber is evacuated. manufacturing device. 2. The semiconductor manufacturing apparatus according to claim 1, wherein a connection point between the bypass passage and the vacuum exhaust passage is located upstream of the pressure regulating valve when viewed from an exhaust direction. 3. The semiconductor manufacturing apparatus according to claim 1, wherein said flow path switching means switches from said first state to said second state immediately before completion of dry cleaning of said main chamber. .