JP2004349641A - Cleaning end point detecting system for cvd apparatus and method of detecting cleaning end point - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new cleaning end point detecting system capable of accurately detecting a cleaning end point of a CVD apparatus with ease and a method of detecting the cleaning end point. <P>SOLUTION: A pair of metal wires 22a and 22b is arranged on an insulating board 21 provided in a chamber 10. An electric signal is transmitted to the metal wires to compare a wiring delay of the electric signal when a reaction product m does not adhere or is not deposited in the chamber 10 with a wiring delay at the start of cleaning, so that a cleaning end point is detected. Thus, it is possible to positively avoid overetching or the like during cleaning, thereby accurately detecting a cleaning end point of the CVD apparatus with ease. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a CVD (Chemical Vapor Deposition) apparatus which is indispensable in a manufacturing process of a semiconductor device, and particularly to detection of a cleaning end point used for removing an excess reaction product adhered and deposited on an inner wall or the like of the CVD apparatus. The present invention relates to a mechanism and a cleaning end point detection method.
[0002]
[Prior art]
Conventionally, in such a CVD apparatus, a reaction product adheres and accumulates on the surfaces of various members such as an inner wall of a chamber, upper and lower electrodes, and a heater cover in addition to a surface of a wafer as a film forming process proceeds.
If such a reaction product is left as it is and the film formation process is continued, the reaction product will eventually peel off and enter the wafer surface as a foreign substance, thereby lowering the yield or changing the impedance in the chamber. This may adversely affect high-frequency output and the like, resulting in defective products. For this reason, conventionally, the inside of the chamber of the CVD apparatus is regularly or always cleaned as needed.
[0003]
For example, in a plasma CVD apparatus, a cleaning gas such as a fluorocarbon-based gas is introduced into a chamber, and a high-frequency voltage is applied to generate fluorine radicals in a plasma atmosphere, and the fluorine radicals decompose and remove excess reaction products. The chamber walls are cleaned by a dry etching method.
By the way, in the cleaning of the inside of the chamber by such a dry etching method, if it is excessive, not only the chamber wall surface but also various parts in the chamber are etched, which may adversely affect the apparatus (eg, over-etching). Therefore, in order to prevent such excessive cleaning, it is important to accurately know the end point of the cleaning.
[0004]
For this reason, conventionally, as shown in the following patent documents, for example, a method of monitoring the emission intensity of fluorine radicals (about 770 nm) or the like, and detecting the change in the emission intensity to detect the end point of cleaning. Proposed.
[0005]
[Patent Document 1]
JP-A-63-35778 [Patent Document 2]
JP-A-7-335615 [Patent Document 3]
JP-A-8-139036
[Problems to be solved by the invention]
By the way, in the method of detecting the cleaning end point based on the change in the plasma light emission intensity in the chamber as described above, since the determination is made based on the plasma light emission intensity of the entire chamber, a local uncleaning which is hardly reflected in the light emission intensity is performed. Therefore, it is not possible to avoid a certain degree of over-etching.
[0007]
In addition, since the plasma emission intensity changes variously depending on various cleaning conditions such as the flow rate and pressure of the cleaning gas and the type of the chamber to be cleaned, the optical emission intensity for detecting the emission intensity is changed each time the cleaning condition or the chamber is changed. It is necessary to adjust the sensitivity and the like of the system, and there is a disadvantage that operation and handling are troublesome.
[0008]
Therefore, the present invention has been devised in order to effectively solve such a problem, and an object thereof is to provide a novel cleaning end point detecting mechanism capable of accurately and easily detecting a cleaning end point of a CVD apparatus. An object of the present invention is to provide a cleaning end point detection method.
[0009]
[Means for Solving the Problems]
[Invention 1]
In order to solve the above-mentioned problems, a cleaning end point detecting mechanism of a CVD apparatus according to Invention 1 is provided.
In a cleaning end point detection mechanism for detecting a time point of removal of a reaction product attached and deposited in a chamber of a CVD apparatus,
A pair of metal wires extending in parallel at predetermined intervals are wired on the inner wall of the chamber and on the surface of the member on which the reaction product adheres and accumulates, and an electric signal is sent to the metal wires. A power supply unit and a wiring delay detector for detecting a wiring delay of an electric signal flowing through the metal wire are provided.
[0010]
That is, in the present invention, a portion where reaction products are likely to adhere and accumulate, such as the inner wall of the chamber, is covered with an insulating plate, and two metal wires are wired in parallel on the insulating plate, and the reaction product is formed between the metal wires. Wiring delay, which is the delay of the electrical signal flowing through the metal wire when it is attached or deposited and when it is not attached or deposited, is detected by a wiring delay detector, and the cleaning end point is detected based on the detected value. It was made.
[0011]
This makes it possible to accurately and easily detect the cleaning end point, as described later, so that inconveniences such as over-etching due to excessive cleaning and adhesion of particles due to insufficient cleaning can be avoided.
In addition, since there is almost no influence from various cleaning conditions such as the flow rate and pressure of the cleaning gas and the type of the chamber to be cleaned, troublesome work such as adjustment of the optical system for detecting the light emission intensity is not required. It becomes.
[0012]
[Invention 2]
The cleaning end point detecting mechanism of the CVD apparatus according to the second aspect of the present invention includes:
In a cleaning end point detection mechanism for detecting a time point of removal of a reaction product attached and deposited in a chamber of a CVD apparatus,
The inner wall of the chamber and the surface of the member in which the reaction product adheres and accumulates in the chamber are covered with an insulating plate, and a pair of metal wires extending in parallel at a predetermined interval are wired on the insulating plate. A power supply unit for transmitting an electric signal to the metal wire, and a wiring delay detector for detecting a wiring delay of the electric signal flowing through the metal wire.
[0013]
That is, the present invention does not directly wire the inner wall of the chamber and the surface of the member on which the reaction product adheres and accumulates as in Invention 1, but covers the surface with an insulating plate, The wiring is made on an insulating plate.
This makes it easy to apply to a chamber where wiring is difficult, and also facilitates the work of replacing wiring.
[0014]
[Invention 3]
A cleaning end point detecting mechanism for a CVD apparatus according to a third aspect of the present invention is the cleaning end point detecting mechanism for a CVD apparatus according to the first aspect.
The present invention is characterized in that a plurality of sets of the pair of metal wires are separately multiplexed on the surface of the insulating plate.
[0015]
As a result, the presence or absence of a reaction product can be detected for each set, so that not only whether the reaction product remains on the inner wall of the chamber or the like, but also the portion where the reaction product has been removed or the remaining portion can be accurately detected. can do.
[Invention 4]
A cleaning end point detecting method for a CVD apparatus according to a fourth aspect of the present invention is a cleaning end point detecting method for detecting a time point at which a reaction product attached and deposited in a chamber of the CVD apparatus is removed.
After wiring a pair of metal wires extending in parallel at a predetermined interval on the inner wall of the chamber and on the surface of the member on which the reaction product adheres and accumulates in the chamber, an electric signal is applied to the metal wires. The wiring delay of the electrical signal when no reaction product is attached or deposited in the chamber is detected as a reference delay value, and when the chamber is cleaned, the electrical signal is detected from the start of the cleaning. , And comparing the detected value with the reference delay value to detect the cleaning end point.
[0016]
This makes it possible to accurately and easily detect the cleaning end point as in the first aspect of the invention, thereby avoiding inconveniences such as over-etching and troublesome operations such as adjustment of the optical system for detecting the emission intensity.
[Invention 5]
A cleaning end point detecting method for a CVD apparatus according to a fifth aspect of the present invention is a cleaning end point detecting method for detecting a time point at which a reaction product attached and deposited in a chamber of the CVD apparatus is removed.
The inner wall of the chamber and the surface of the member in which the reaction product adheres and accumulates in the chamber are covered with an insulating plate, and a pair of metal wires extending in parallel at a predetermined interval are wired on the insulating plate. After that, an electric signal is sent to the metal wire, and a wiring delay of the electric signal when no reaction product is attached or deposited in the chamber is detected as a reference delay value. The present invention is characterized in that a wiring delay of the electric signal is detected from the start of the cleaning, and the detected value is compared with the reference delay value to detect a cleaning end point.
[0017]
Thus, similarly to the second aspect, the present invention can be easily applied to a chamber in which wiring is difficult, and the work of replacing wiring can be easily performed.
[Invention 6]
A method for detecting a cleaning end point of a CVD apparatus according to a sixth aspect of the present invention is the method for detecting a cleaning end point of a CVD apparatus according to the fourth or fifth aspect.
The invention is characterized in that a plurality of the pair of metal wires are independently wired.
[0018]
This makes it possible to detect the presence or absence of a reaction product for each set, similarly to the third aspect, so that not only the presence or absence of the reaction product on the inner wall of the chamber or the like, but also the portion where the reaction product has been removed or the remaining product Even parts can be accurately detected.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows an embodiment of a plasma CVD apparatus in which a source gas is decomposed by plasma and deposited on a wafer W in a CVD apparatus according to the present invention.
[0020]
In the figure, reference numeral 10 denotes a chamber formed of a vacuum vessel used as a reaction furnace. In the chamber 10, a shower head (upper electrode) 12 for blowing a reaction gas or a cleaning gas in a shower shape, and a wafer W are provided. The wafer stage (lower electrode) 14 to be heated and held is housed so as to face up and down.
Further, the chamber 10 is provided with a high-frequency power supply 16 and a vacuum pump 18 and the like. The chamber 10 is evacuated, and the high-frequency power supply 16 is used to bring the shower head 12 and the wafer stage 14 into a plasma state. The supplied reaction gas is decomposed and stacked on the wafer W.
[0021]
As shown in the figure, a cleaning end point detection mechanism 20 is provided on the inner wall surface of the chamber 10 and the surface of a member housed in the chamber 10 such as the shower head 12 and the wafer stage 14 for each wall surface or each member. Each is provided independently.
As shown in FIGS. 2 and 3, the cleaning end point detecting mechanism 20 is made of aluminum or the like on the surface of an insulating plate 21 made of a glass plate or the like provided to cover the inner wall surface of the chamber 10 or the surface of the member. A pair of metal wires 22a and 22b are wired in parallel at a predetermined interval, and a power supply unit 23 for sending an electrical signal to one of the metal wires 22a and a wiring delay of an electrical signal flowing through the metal wire 22 are detected. And a wiring delay detector 24.
[0022]
Further, as shown in the figure, the pair of metal wires 22a and 22b are independently and concentrically wired on the surface of the insulating plate 21, and the respective metal wires 22a are independently and independently connected to the power supply unit 23 and the wiring delay detector. Connected to the means 24.
The wiring delay detecting means 24 has a function of detecting and storing a wiring delay of an electric signal generated from the power supply unit 23 for each metal line 22a.
[0023]
In FIG. 1, gaps are formed between the inner wall surface of the chamber 10 and the respective insulating plates 21 in order to clearly show the installation state of the cleaning end point detecting mechanism 20. The insulating plates 21 are provided in close contact with their inner wall surfaces and the like so that gas and reaction products (hereinafter, appropriately referred to as “deposit film”) and the like do not enter the inside.
[0024]
The operation and effect of the cleaning end point detecting mechanism 20 of the CVD apparatus having such a configuration will be described above.
First, as shown in FIG. 2, for example, in a state of a new product or a case where cleaning is completely performed and no reaction product is attached to the insulating plate 21 of the cleaning end point detection mechanism 20, each metal wire 22 a, 22 b A wiring delay for each is detected and stored as a reference delay value.
[0025]
Here, since the wiring delay varies depending on the resistance, pitch (interval), and the like of each wiring as described later, it is necessary to detect and store the wiring delay for each of the metal lines 22a and 22b. Is essential. The detection and storage of these wiring delays are further performed for all the cleaning end point detection mechanisms 20.
Next, if the wiring delay of each wiring in a state where no reaction product is attached is detected and stored as a reference delay value in this manner, the CVD apparatus provided with the cleaning end point detecting mechanism 20 is provided. Is used as it is as a normal film forming apparatus, but with this use, a part of the reaction product generated in the chamber 10 gradually becomes on the surface of the insulating plate 21 of the cleaning end point detecting mechanism 20. As shown in FIG. 3, the metal wires 22a and 22b are gradually deposited so as to cover the metal wires 22a and 22b, thereby forming a deposition film m. Therefore, in such a state, the inside of the chamber 10 must be cleaned in order to prevent contamination or the like by a reaction product separated from the deposition film m.
[0026]
Here, the cleaning in the plasma CVD apparatus is so-called plasma cleaning, as described above, and is performed by glow discharge while flowing a fluorine-based gas such as CF ₄ or an inert gas such as Ar into the chamber 10. The gas is dissociated into an electron, ion, and radical states to form a plasma state, and the reaction product m remaining in the chamber 10 is decomposed using the plasma state. The decomposed reaction product m is converted into a volatile reaction product by a chemical reaction caused by the activating force of ions and radicals, and is evacuated. As a result, the deposition film m in the chamber 10 is removed and cleaning is performed.
[0027]
Then, the present invention detects the wiring delay for each wiring continuously from the time when such cleaning is started, and detects the end point of the cleaning by comparing the detected value with a previously stored reference delay value. It is like that.
That is, the wiring delay is one of the phenomena that hinders obtaining a high-speed semiconductor device in the semiconductor manufacturing field, for example. In general, the product of the resistance R of the wiring (metal line) and the capacitance C between the wirings (metal lines). The capacitance C between wires (metal lines) is proportional (change) to the pitch l between wires (metal lines) and the dielectric constant ε of an insulator around the wires, that is, the wiring delay ΔRC (C ∝lε).
[0028]
In the present embodiment, since the wiring resistance R and the pitch l between the wirings are constant, the fluctuation parameter of the wiring delay is the dielectric constant ε of the insulator around the metal wire 22, that is, the air or the deposition film m. Only.
Therefore, if the deposition film m does not exist between the metal lines 22a and 22b, the space between the metal lines 22a and 22b is filled with air, so that the dielectric constant ε is low, and the wiring delay is always constant. On the other hand, if the deposition film m exists between the metal lines 22a and 22b, the dielectric constant ε increases, and the wiring delay also changes. Incidentally, a typical dielectric constant of SiO ₂ as a reaction product is 3.9.
[0029]
Therefore, by determining the difference between the two wiring delays, it is possible to accurately and easily specify the time at which the surrounding film has disappeared, that is, the time at which the cleaning is completed.
As described above, according to the present invention, the deposition film m is electrically removed instead of detecting whether or not the reaction product deposited and deposited in the chamber of the CVD apparatus is removed from the emission intensity of the plasma as in the related art. This is to detect whether or not it has been fired.
[0030]
As a result, the cleaning end point can be accurately and easily detected, so that inconveniences such as over-etching can be avoided beforehand. Since it is hardly affected by the type of the chamber or the like, complicated work such as adjustment of the optical system for detecting the light emission intensity is not required.
[0031]
Further, in the present embodiment, since the presence of the deposition film m can be detected for each of the metal wires 22a and 22b (pair), not only whether the deposition film m remains on the inner wall of the chamber 10 or the like, but also that It is possible to accurately detect even a removed portion or a remaining portion.
This makes it possible to specify a portion that is likely to be attached and deposited, so that the gas flow can be accurately grasped, which can greatly contribute to the subsequent design, research and development, etc. of the chamber 10.
[0032]
Although the embodiment shown in FIG. 3 is an example in which the metal wires 22a and 22b are wired concentrically in an elliptical shape, the wiring method is not limited to this. As shown in the figure, the wiring is formed in a rectangular shape, or the wiring is formed in a meandering manner, or if the location where the deposition film m is deposited / deposited is known in advance depending on the type of the chamber 10, only in that location or in the location The wiring may be densely provided at the location.
[0033]
In the present embodiment, the metal wires 22a and 22b are wired on the surface of the insulating plate 21, but since the chamber 10 is generally made of an insulating material, the metal wires 22a and 22b are directly provided on the inner surface of the chamber 10. , 22b, the insulating plate 21 of the cleaning end point detecting mechanism 20 on the chamber 10 side can be omitted.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an embodiment of a CVD apparatus and a cleaning mechanism.
FIG. 2 is a view in the direction of arrow A in FIG.
FIG. 3 is an enlarged sectional view taken along line aa ′ in FIG. 2;
FIG. 4 is a front view showing another embodiment of the cleaning mechanism.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Chamber, 12 ... Shower head (upper electrode), 14 ... Wafer stage (lower electrode), 16 ... High frequency power supply, 18 ... Vacuum pump, 20 ... Cleaning mechanism, 21 ... Insulating plate, 22 ... Metal wire, 23 ... Power supply, 24: wire delay detector, W: wafer, m: reaction product (deposited film).

Claims (6)

In a cleaning end point detection mechanism for detecting a time point of removal of a reaction product attached and deposited in a chamber of a CVD apparatus,
A pair of metal wires extending in parallel at predetermined intervals are wired on the inner wall of the chamber and on the surface of the member on which the reaction product adheres and accumulates, and an electric signal is sent to the metal wires. A cleaning end point detection mechanism for a CVD apparatus, comprising: a power supply section; and a wiring delay detector for detecting a wiring delay of an electric signal flowing through the metal wire. In a cleaning end point detection mechanism for detecting a time point of removal of a reaction product attached and deposited in a chamber of a CVD apparatus,
The inner wall of the chamber and the surface of the member in which the reaction product adheres and accumulates in the chamber are covered with an insulating plate, and a pair of metal wires extending in parallel at a predetermined interval are wired on the insulating plate. And a power supply unit for transmitting an electric signal to the metal wire, and a wiring delay detector for detecting a wiring delay of the electric signal flowing through the metal wire. The cleaning end point detection mechanism for a CVD apparatus according to claim 1 or 2,
A cleaning end point detecting mechanism for a CVD apparatus, wherein a plurality of sets of the pair of metal wires are individually and multiplexed on the surface of the insulating plate. In a cleaning end point detection method for detecting a time point of removal of a reaction product adhered and deposited in a chamber of a CVD apparatus,
After wiring a pair of metal wires extending in parallel at a predetermined interval on the inner wall of the chamber and on the surface of the member on which the reaction product adheres and accumulates in the chamber, an electric signal is applied to the metal wires. The wiring delay of the electrical signal when no reaction product is attached or deposited in the chamber is detected as a reference delay value, and when the chamber is cleaned, the electrical signal is detected from the start of the cleaning. A method of detecting a cleaning end point of a CVD apparatus, comprising detecting a wiring delay, and comparing the detected value with the reference delay value to detect a cleaning end point. In a cleaning end point detection method for detecting a time point of removal of a reaction product adhered and deposited in a chamber of a CVD apparatus,
The inner wall of the chamber and the surface of the member on which the reaction product adheres and accumulates in the chamber are covered with an insulating plate, and a pair of metal wires extending in parallel at a predetermined interval are wired on the insulating plate. After that, an electric signal is sent to the metal wire, and a wiring delay of the electric signal when no reaction product is attached or deposited in the chamber is detected as a reference delay value, and the cleaning in the chamber is performed. Detecting a wiring delay of the electrical signal from the cleaning start time and comparing the detected value with the reference delay value to detect a cleaning end point. . The cleaning end point detection method for a CVD apparatus according to claim 4 or 5,
A method of detecting a cleaning end point of a CVD apparatus, wherein a plurality of the pair of metal wires are independently wired.

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