JP2014045113A - Endpoint detector - Google Patents

Abstract

Provided is an endpoint detector for notifying an optimal maintenance time for performing detection window cleaning when plasma emission intensity is reduced due to contamination of the detection window.
In an end point detector 1 of plasma application equipment, a detection window 4 is clouded due to attachment of reactive organisms by a process gas, and an accurate end point cannot be detected, resulting in defective products due to overetching. The emission intensity when the detection window is not dirty is sampled for each specific wavelength and compared with the sampled emission intensity, and the detection level of the emission intensity is reduced by the output signal from the endpoint monitor. To inform. As a result, it is possible to know the timing for notifying when the detection window is to be maintained.
[Selection] Figure 1

Description

  The present invention relates to an end point detector that detects a processing end time of a plasma application device using a spectroscopic measurement device using a spectroscopic sensor.

  Conventionally, in plasma application equipment, a detection window is provided in a processing chamber, light generated during plasma processing is detected from this window, and the emission intensity of light of a specific wavelength and its change are measured from the detected light. An end point is determined. In the conventional endpoint detector 101 shown in FIG. 6, the light generated from the plasma is dispersed by the spectroscopic sensor unit 112 through the condensing unit 102 that condenses the detected light, the optical fiber 103, and the slit 111, and the spectral light is separated. The end point signal is sent to the host controller via the cable 107 from the I / F board 113 that performs arithmetic processing on the signal obtained in this manner.

  For example, in the case of plasma etching, plasma is generated in the processing chamber and etching is started. At the same time, light from the plasma is detected through a detection window provided in the processing chamber, and the detected light is dispersed to obtain emission intensity of a specific wavelength. When monitored, the plasma emission intensity increases with the start of etching during etching, and stabilizes at a high level while the film to be etched remains. When the etching progresses and the film to be etched disappears, it rapidly decreases. When the etching reaches the end point of etching, the emission intensity decreases and the end point of etching can be known (see FIG. 4).

  Thus, since the level of the emission intensity changes according to the progress of the etching, the end point of the etching process can be determined based on the change in the emission intensity so as not to overetch. In the case of plasma CVD, plasma cleaning is periodically performed by introducing an etching gas into the apparatus. If the light from the plasma is detected from the detection window provided in the processing chamber during the cleaning process, and the emission intensity at a specific wavelength is monitored by analyzing the detected light, the emission intensity is the same as that in the above etching process. Shows behavior. Therefore, the cleaning end point can be determined based on the change in the emission intensity. The same technique is used when determining the maintenance time of the transmissive window glass for curing the semiconductor substrate (see Patent Document 1), and also for detecting dirt on the transmissive window in the particle counter. (See Patent Document 2).

JP 2009-272595 A JP 2010-151811 A

  As described above, processing end point detection based on the plasma emission intensity during processing is often used in plasma application equipment that performs processing using plasma. FIG. 2 shows a schematic diagram of the entire system including the endpoint detector. The detection level of the emission intensity from the plasma is taken into the endpoint detector 1 through the light collecting unit 2 and the optical fiber 3 from the detection window 4 provided in the process chamber. However, in the method of detecting the emission intensity of the plasma in the processing chamber from the above-described detection window, if the apparatus is used repeatedly, the detection window becomes cloudy due to factors such as adhesion of reaction products due to various process gases. There is a problem that the detection level of the emission intensity is lowered. As shown in FIG. 5, when the detection window becomes cloudy and the emission intensity decreases, the peak value of the emission intensity and the amount of change in the emission intensity at the etching end point become small, making it difficult to detect the end point.

  As described above, when the detection level of the emission intensity is lowered, it is difficult to accurately detect the end point timing, which causes overetching and the like, resulting in frequent defective products. In order to prevent the occurrence of defective products due to such over-etching, it is necessary to periodically clean the detection window. However, the plasma application equipment must open the vacuum for cleaning, and requires a considerable amount of time for cleaning. Therefore, if the number of times of cleaning is large, the overall process processing efficiency is significantly reduced. Problems arise.

  The present invention solves the above-described conventional problems, and performs an endpoint detection window in a plasma application device that can perform cleaning at an appropriate timing and can detect the endpoint accurately with the least number of cleanings as possible. The purpose is to clarify the optimal maintenance (cleaning) time.

  In order to solve the above-mentioned problem, regarding a process including plasma processing performed in an external process chamber, an endpoint for monitoring the light emitted from a detection window provided in the process chamber and detecting the end time of the plasma processing In the detector, a monitor unit that monitors a detection level of the emission intensity from the plasma, a storage unit that stores a maximum value of the detection level when the detection window is not dirty, and a maximum value of the detection level A switching unit that switches setting of a plurality of threshold values corresponding to a plurality of process conditions, a determination unit that compares the threshold set by the switching unit with the maximum value of the detection level, and a determination result of the determination unit Is provided with a display unit for notifying the appropriate maintenance time of the detection window.

  In addition, the present invention is characterized by comprising an external output means for outputting a signal notifying the maintenance time of the detection window to the outside.

In addition, the present invention may have a plurality of storage units and a determination unit so as to be able to cope with a plurality of processes so as to cope with a case where a new process occurs.
As a result of these, it is possible to notify the detection of the optimum maintenance timing of the endpoint detection window.

  According to the endpoint detector of the present invention, when the detection level of the light emission intensity from the plasma due to the contamination of the detection window decreases, the timing of cleaning the detection window can be known in a timely manner, which causes overetching and the like. It is possible to prevent the occurrence of problems that frequently cause defective products, and it is not necessary to perform excessive cleaning, and cleaning can be performed at an optimal maintenance time.

1 is a schematic diagram of an endpoint detector of the present invention. 1 represents a schematic diagram of the entire system including an endpoint detector. FIG. 6 is a schematic diagram of another embodiment of the endpoint detector of the present invention. It is a conceptual diagram showing the time change of the emitted light intensity of a specific wavelength. In FIG. 4, it is a conceptual diagram showing that the detection window is clouded by the adhesion of the reaction product by the process gas and the emission intensity is lowered. It is a schematic diagram of a conventional endpoint detector.

An embodiment of the present invention will be described with reference to FIGS.
FIG. 1 shows an overview of the endpoint detector. FIG. 2 shows the entire system including the endpoint detector, which is composed of a process chamber 5, an endpoint detector 1, a host controller 6, a condensing unit 2 connecting them, an optical fiber 3, a detection window 4, and a cable 7. Has been. A detection window 4 is provided above the process chamber 5, and the plasma light in the process chamber is collected by the light collecting unit 2 through the detection window 4. The collected light is sent as an optical signal to the endpoint detector 1 through the optical fiber 3. The end point detector 1 issues a signal notifying the end point time and transmits the signal to the host controller 6 via the cable 7.

  The end point detector 1 performs an arithmetic process on a signal obtained through the slit 11 using the spectroscopic sensor unit 12 and the I / F substrate 13. The emission intensity of plasma increases, for example, as etching progresses in a semiconductor etching apparatus, but the emission intensity at a specific wavelength caused by the etched layer decreases rapidly as the etched layer disappears. To do. FIG. 4 shows how the emission intensity decreases.

  The peak value of the emission intensity is stored in the storage unit 15 for each specific wavelength when the detection window is not soiled, that is, when it is used for the first time or after cleaning. The storage unit 15 sets a certain percentage (for example, 80%) of the maximum value as a threshold value. The threshold can also be set and changed depending on the process conditions. Every time from the next etching, the maximum value of the detection level of the emission intensity is observed by the monitor unit 14 for each specific wavelength. The determination unit 19 compares the value observed by the monitor unit 14 with the threshold value stored in the storage unit 15. If the monitor value falls below the threshold value, the display unit 20 needs to maintain the detection window 4. Inform sex. As a notification method, the end point detector 1 can display on the display unit 20 such as an LED, or can be displayed on the host controller 6 by an output signal.

  Moreover, although the switching part 16 for every process is provided, when it performs by a different process, it is memorize | stored for every process in the setting 1 (17-1) ... setting X (17-X), and for every process The one set by the switching unit 16 is used. If another process is performed on the host controller side, the discriminating unit 19 discriminates with different set values, so that it is displayed without an accurate judgment. In order to prevent this, a plurality of settings are prepared, and when the process is changed, the operator can change the setting by the switching unit 16 for each process.

  FIG. 3, which is another embodiment of the present invention, will be described. 3, similarly to FIG. 1, through the slit 11, an I / F board 13 that performs arithmetic processing on a signal obtained by performing spectroscopy with the spectral sensor unit 12, and a storage unit 15 connected to the I / F board 13, A switching unit 16 and a determination unit 19 are provided. In addition, the second storage unit 21 stores the previous data, the second determination unit 22 separates the current data (data of the monitor unit 14), and the display unit 20 The result is displayed or a signal is output to the host controller 6 to check whether the setting of the switching unit 16 is correct. As a result, a plurality of storage units and discriminating units can be provided corresponding to a plurality of processes, and a more accurate end point detection time can be notified.

  In FIG. 1 to FIG. 3, the same reference numerals indicate the same items and have the same functions.

DESCRIPTION OF SYMBOLS 1 End point detector 2 Condensing part 3 Optical fiber 4 Detection window 5 Process chamber 6 Host controller 7 Cable 11 Slit 12 Spectroscopic sensor unit 13 I / F board 14 Monitor part 15 Memory | storage part 16 Switching part 17 Setting 19 Discriminating part 20 Display Unit 21 second storage unit 22 second discrimination unit 101 end point detector 102 condensing unit 103 optical fiber 107 cable 111 slit 112 spectral sensor unit 113 I / F substrate

Claims (3)

With respect to a process including plasma processing performed in an external process chamber, an endpoint detector that detects the end time of plasma processing by monitoring light emitted from a detection window provided in the process chamber,
A monitor for monitoring the detection level of the emission intensity from the plasma, a storage for storing the maximum value of the detection level when the detection window is not soiled, and a plurality of processes for the maximum value of the detection level A switching unit that switches setting of a plurality of threshold values corresponding to the condition, a determination unit that compares the threshold value set by the switching unit with the maximum value of the detection level, and the detection window based on the determination result of the determination unit An end point detector characterized by comprising a display unit for informing the appropriate maintenance time.   2. The endpoint detector according to claim 1, further comprising external output means for outputting a signal notifying the maintenance time of the detection window to the outside.   3. The endpoint detector according to claim 1, wherein the endpoint detector has a plurality of storage units and a determination unit so that it can cope with a case where a new process occurs, and can cope with a plurality of processes. .