JP2001262355A - Plasma, cvd system, and method for detecting its malfunction - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the malfunction of a susceptor before it occurs, to prevent the occurrence of defective articles, and to improve yield. SOLUTION: A plasma CVD system 1, where plasma is generated between a couple of parallel plate RF electrodes disposed in a chamber 2 to deposit a film on the surface of a wafer placed on one of the RF electrode, is provided. This plasma CVD system 1 is provided with the following: an RF generator 3 for supplying high frequency voltage to the RF electrodes; an RF matching box 4 disposed between the RF generator 3 and the RF electrodes; a DC bias detecting means for detecting DC bias signals from the RF matching box 4; and a judging means 5a for judging the presence of arcing in the chamber 2 on the basis of the detected DC bias signals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a high-frequency plasma CVD apparatus and a method for detecting an abnormality thereof.

[0002]

2. Description of the Related Art A high-frequency plasma CVD apparatus supplies a process gas into a chamber accommodating a pair of parallel plate RF electrodes, and supplies a high-frequency voltage while controlling the temperature and pressure to generate plasma between the RF electrodes. This is an apparatus that forms a film on the surface of a wafer placed on a susceptor that forms one of the RF electrodes by generating the RF electrode.

In such a high-frequency plasma CVD apparatus, when a film forming process is repeated many times, an RF electrode, particularly a wafer, is mounted by plasma generated inside the chamber in each process or for other reasons. The susceptor is damaged over time, and a trouble such as an abnormal grounding occurs. Such a defect causes a change in process conditions in the chamber, thereby causing a defective product with reduced quality.

[0004] For this reason, conventionally, the presence or absence of abnormality in the susceptor has been determined by periodically sampling the manufactured wafers every predetermined number of film forming processes and checking the quality thereof.

[0005]

However, since such a conventional abnormality detection method checks an actually manufactured product, if the sampling cycle is long, the quality has already deteriorated. It is also conceivable that defective products are manufactured in large quantities. In this case,
Not only is there material waste that large quantities of defective products that cannot be reused are manufactured, but also time and costs required for manufacturing defective products are generated, resulting in a great disadvantage.

On the other hand, if the sampling period is shortened,
Although the occurrence of the above inconvenience can be reduced, there is an inconvenience that unnecessary sampling must be frequently performed in a short cycle even when the susceptor is in a normal state. Further, even if the sampling cycle is shortened, the conventional abnormality detection method for checking manufactured products has a disadvantage that not a few defective products are generated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described inconvenience, and it is an object of the present invention to detect a failure of a susceptor before the occurrence thereof, prevent a defective product from occurring, and improve the yield. The purpose is.

[0008]

According to the present invention, a plasma is generated between a pair of parallel plate RF electrodes disposed in a chamber, and the plasma is placed on one of the RF electrodes. A plasma CVD apparatus for forming a film on the surface of a wafer, wherein the RF electrode supplies a high-frequency voltage to the RF electrode.
A power supply, and an RF matching box disposed between the RF electrode and the RF power supply; and a DC bias detecting means for detecting a DC bias signal from the RF matching box; There is proposed a plasma CVD apparatus including a determination unit for determining whether arcing has occurred in the chamber based on the determination.

The plasma CVD apparatus may further include an interlock means for stopping a film forming process based on an output of the determination means.
Further, the interlock means may stop the progress to the next process at the end of the film forming process.

Further, according to the present invention, a plasma is generated between a pair of parallel plate RF electrodes disposed in a chamber,
In a plasma CVD apparatus for forming a film on the surface of a wafer placed on one of the RF electrodes, a DC matching box disposed between the RF power supply for supplying a high-frequency voltage to the RF electrode and the RF electrode has a DC. An abnormality detection method for a plasma CVD apparatus that detects a bias signal and determines whether or not arcing has occurred in the chamber based on the detected DC bias signal has been proposed.

In this abnormality detection method, the determination of the presence / absence of abnormality of the RF electrode is performed by calculating an average value of the DC bias signal at the time of film formation and calculating the average value and the maximum value and the minimum value of the DC bias signal. Calculate a difference value with either one or both, and when the difference value is larger than a predetermined threshold,
It may be determined that arcing has occurred in the chamber.

[0012]

According to the plasma CVD apparatus of the present invention,
The DC bias detection means detects a DC bias signal from an RF matching box disposed between the RF power supply and the RF electrode, and the determination means determines whether arcing has occurred in the chamber based on the detected DC bias signal. to decide. The DC bias signal indicates the potential of the RF electrode. When arcing occurs in the chamber, the DC bias signal changes significantly. The occurrence of arcing does not immediately lead to fluctuations in process conditions, but in many cases, an abnormality has occurred in the RF electrode, and if left unchecked, it will lead to the generation of defective products. is there. Therefore,
By detecting and evaluating this DC bias signal, it is possible to determine whether or not arcing has occurred in the chamber, which is different from the conventional technology in which an abnormality of the RF electrode is found only after a defective product has occurred. In addition, it is possible to prevent defective products from occurring.

Further, by providing interlock means for stopping the film forming process based on the output of the judgment means, the process can be stopped immediately after the occurrence of an abnormality in the RF electrode. As a result, it is possible to eliminate waste of sampling periodically and efficiently prevent defective products.

Further, if the interlock means stops the progress to the next process at the end of the film forming process, the process determined to be abnormal by the determining means can be completed without interruption. It is possible to prevent a product being manufactured from becoming defective. D
Plasma C of the Present Invention Determined Based on C Bias Signal
In the VD apparatus, even when the determination means determines that arcing has occurred, it can be sufficiently considered that the process conditions do not fluctuate so as to affect the product. This is to prevent the product from becoming defective.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A plasma CVD apparatus according to one embodiment of the present invention will be described below with reference to FIG. As shown in FIG. 1, a plasma CVD apparatus 1 according to the present embodiment includes a chamber 2 in which a pair of parallel plate RF electrodes (not shown) is disposed, and the R of the chamber 2.
An RF power supply 3 for supplying a high-frequency voltage to the F electrode, an RF matching box 4 disposed between the RF power supply 3 and the RF electrode, and a control device 5 connected to the RF matching box 4 are provided. ing.

The RF power source 3 is, for example, a generally used one of 13.56 MHz and has an output impedance of 50Ω. However, the present invention is not limited to this. The RF matching box 4 is an impedance matching circuit for matching the output impedance of the RF power source 3 with the input impedance of the plasma load formed by the RF electrodes in the chamber 2 and has an internal signal as an internal signal. , Blocking capacitor (DC bias detector: not shown)
DC bias signal A indicating the potential of the RF electrode
Can be detected.

The control device 5 may constitute a part of the system control device 6, for example, or may be constituted by a general-purpose device such as a sequencer. The controller 5 performs an arithmetic process on the detected DC bias signal A for each period of the film forming process to determine whether or not arcing has occurred in the chamber 2, and that the arcing has occurred. An interlock unit 5b for stopping the subsequent processes when the judgment is made.

The determination section 5a stores in advance a threshold value determined according to the type of the film forming process, calculates an average value of the DC bias signal A for each film forming process, and A signal indicating the occurrence of arcing in the chamber 2 by calculating a difference value between the maximum value and / or the minimum value of the DC bias signal A and the average value, and comparing the difference value with the threshold value. B can be output.

The interlock unit 5b includes a judgment unit 5a
In response to the arcing generation output B from the system, an interlock signal C for stopping the process when the film forming process being executed is completed is sent to the system controller 6 so that the process does not proceed to the subsequent processes. Has become.

The operation of the thus-configured plasma CVD apparatus 1 according to the present embodiment will be described below.
According to the plasma CVD apparatus 1 according to the present embodiment, when the film forming process is started, the DC bias signal A detected from the DC bias detection unit of the RF matching box 4 is used.
Are sequentially sent to the determination unit 5a of the control device 5. The determination unit 5a calculates an average value of the DC bias signal A over one period of the film forming process, and holds the maximum value and the minimum value of the DC bias signal A during the same period.

Then, a difference value indicating how far the maximum value and / or minimum value of the DC bias signal A deviates from the average value is calculated and compared with a threshold value stored in advance. Under normal conditions, DC
The bias signal A indicates a constant value with little fluctuation. Therefore, when the difference value is smaller than the threshold value, the determination unit 5a determines that the RF electrode is normal without arcing and does not break, and outputs a signal indicating that the RF electrode is normal. Alternatively, the process proceeds to the next film forming process without outputting the arcing generation signal B.

On the other hand, when arcing occurs in the chamber 2, the DC bias signal A does not have a constant value but has a distinct variation. Therefore, when the difference value is larger than the threshold value, the determination unit 5a outputs a signal B indicating that arcing has occurred.

The arcing occurrence signal B output from the determination section 5a is input to the interlock section 5b. As a result, the interlock unit 5b does not immediately stop the film forming process, but activates the film forming process until the film forming process is completely completed, and then stops the interlocking unit for stopping the progress to the next film forming process. The lock signal C is output to the system controller 6. At the same time, an alarm signal indicating abnormality may be output. In addition, when the abnormality of the RF electrode can be more reliably detected depending on the setting conditions, the film forming process may be stopped immediately.

When the progress of the process stops, the operator
It is checked whether an abnormality has occurred in the RF electrode in the chamber 2, particularly in the susceptor. If an abnormality has occurred in the RF electrode, replace it. If no abnormality is found, the next film forming process is executed, and the process is continued again until the interlock unit 5b stops the progress of the process.

In this case, according to the plasma CVD apparatus 1 of the present embodiment, the occurrence of arcing in the chamber 2 is detected by monitoring the DC bias signal A. An abnormality of the RF electrode can be detected. As a result, unlike a conventional plasma CVD apparatus that periodically samples a product and finds an abnormality in the RF electrode after the quality has deteriorated, it is necessary to generate a large number of defective products and to manufacture the defective products. Waste of time and cost can be reliably prevented.

The operation of the interlock unit 5b stops the progress to the next process after the completion of the film forming process, thereby preventing the wafer being manufactured from becoming defective due to the interruption of the process. Can be.

[0027]

As described above, according to the plasma CVD apparatus of the present invention, the occurrence of arcing in the chamber is detected by monitoring the potential of the RF electrode, and the production is performed based on the detected arcing. Since the film process is stopped, it is possible to detect abnormalities such as abnormal grounding of the RF electrode before defective products with reduced product quality occur, minimizing the occurrence of defective products and increasing the yield. Is achieved.

[Brief description of the drawings]

FIG. 1 is a plasma CVD according to an embodiment of the present invention.
It is a figure which shows an apparatus schematically.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plasma CVD apparatus 2 Chamber 3 RF electrode 4 RF matching box 5 Controller 5a Judgment part 5b Interlock part

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masayoshi Nohira 14-3 Shinsen, Narita-shi, Chiba Nogehira Industrial Park Inside Applied Materials Japan Co., Ltd. (72) Inventor Hideyuki Iwata 14-3 Shinizumi, Narita-shi, Chiba Noge Applied Materials Japan Co., Ltd. (72) Inventor Kozo Ichiki 14-3 Shinizumi, Narita City, Chiba Prefecture Nogedaira Industrial Park Applied Materials Japan Co., Ltd. F-term (reference) 4K030 FA03 KA30 KA39

Claims (5)

[Claims] 1. A plasma CVD apparatus for generating plasma between a pair of parallel flat plate RF electrodes disposed in a chamber and forming a film on a surface of a wafer mounted on one of the RF electrodes, DC bias detection means, comprising: an RF power supply for supplying a high-frequency voltage to an RF electrode; and an RF matching box disposed between the RF electrode and the RF power supply, and detecting a DC bias signal from the RF matching box. And a determination means for determining whether arcing has occurred in the chamber based on the detected DC bias signal. 2. The plasma CVD apparatus according to claim 1, further comprising an interlock means for stopping a film forming process based on an output of said judgment means. 3. The plasma CVD apparatus according to claim 2, wherein said interlock means stops progress to the next process when the film forming process is completed. 4. A plasma CVD apparatus which generates plasma between a pair of parallel flat plate RF electrodes disposed in a chamber and forms a film on a surface of a wafer mounted on one of the RF electrodes, wherein the RF electrode Power supply for supplying a high-frequency voltage to the
A plasma CVD apparatus, comprising: detecting a DC bias signal from an RF matching box disposed between the F electrode and the DC bias signal; and determining whether arcing has occurred in the chamber based on the detected DC bias signal. Abnormality detection method. 5. The method according to claim 1, wherein the determination of the presence or absence of an abnormality in the RF electrode includes calculating an average value of the DC bias signal at the time of film formation, and calculating the average value and one or both of the maximum value and the minimum value of the DC bias signal. 5. The abnormality of the plasma CVD apparatus according to claim 4, wherein a difference value from the calculated value is calculated, and when the difference value is larger than a predetermined threshold value, it is determined that arcing has occurred in the chamber. Detection method.