JPS63222432A - Equipment manufacturing semiconductor device - Google Patents

Abstract

PURPOSE:To perform monitoring and control readily and effectively, by monitoring the change in a light emitting state of gas plasma in etching operation all the time, and detecting abnormality based on the change in said light emitting state. CONSTITUTION:A detecting sensor 21, which is located at the outside of a chamber 1, always monitors the change in the state of plasma, which is generated in an etching chamber 1a. The light signal, which is detected with the sensor 21, is taken out as a voltage output through, e.g., an optical transistor 23, a low-pass filter 24 and a voltage transformation circuit 25. The detected voltage signal 26, which is obtained in this way, and a preset reference voltage signal 28, which is obtained from a reference voltage generating circuit 27, are compared in a comparator circuit 29. Then the abnormality of the parameter of each operating condition and the abnormality of the equipment at the time of etching are quickly detected readily based on the change in plasma state. Thus the equipment is effectively monitored and controlled.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an apparatus for manufacturing semiconductor devices, and more specifically, to an improvement in a plasma etching apparatus applied to the manufacture of semiconductor devices such as ICs and LSIs. It is.

[Conventional technology]

A conventional manufacturing apparatus for this type of semiconductor device.

In this case, the general structure of the plasma etching apparatus is schematically shown in FIG. 5, and the mode of the gas interlock mechanism in the same apparatus is shown in FIG. 6.

That is, in each of these figures of the conventional example, reference numeral 1 denotes a chamber in which an etching chamber 1a is formed; 2.
and 3 are an upper electrode and a lower electrode arranged at the upper and lower parts of this etching chamber la, and on the lower electrode 3, a semiconductor substrate (semiconductor wafer) 4 as an object to be etched is placed. Place and hold.

Also, 5. and 6 are an exhaust pipe connected to a vacuum pump (not shown) for evacuating the inside of the etching chamber la, and a supply pipe connected to a gas supply source (not shown) for supplying etching gas into the etching chamber la. Etching gas is supplied and discharged as shown by thin arrows. Reference numeral 7 denotes a high frequency power source connected to the upper and lower electrodes 2.3 by conductive wires 8 and applying a high frequency voltage for etching to the upper electrode 3. As is well known, the application of this high frequency voltage The supplied etching gas is turned into plasma, and the desired etching is performed using this plasma.

Furthermore, a flow rate sensor 9 is arranged upstream of the supply pipe 8 to detect the flow rate of the etching gas flowing inside the pipe, and 10 is arranged downstream of the supply pipe θ to detect the flow rate of the etching gas flowing inside the pipe. 11 is a control circuit for these; in this case,
The flow rate signal 13 detected by the flow rate sensor 9 and the bridge circuit 12 and amplified by the amplifier circuit 14 is a flow rate setting signal 1 preset by the flow rate setting circuit 15.
8, the comparison control circuit 17 and the comparison circuit 1 day, and when the gas flow rate is not within the set flow rate range, the comparison circuit 17 outputs a control signal 18 to vary the flow rate variable valve 10. In other words, if the flow rate is not controlled for some reason, the comparison control circuit 1B outputs an alarm signal 20 to warn the outside.

In the case of this type of plasma etching apparatus, in order to perform etching with high precision and good reproducibility, the following preset conditions are maintained in the etching chamber la during the entire etching operation. It is always kept at a constant value. That is, these conditions are: a) Pressure.

b) Gas flow rate.

c) RF output and its reflected wave.

d) Temperature of the upper and lower electrodes.

e) Distance between the upper and lower electrodes.

If any one of these parameters deviates from the set value, it will not be possible to achieve the desired etching finish, so sufficient control and management is required. When certain conditions cannot be maintained, this abnormality must be detected early and a warning must be given to the outside.

Therefore, in the case of the conventional device, the gas interlock mechanism shown in FIG. 6 described above is employed to automatically control the most important gas flow rate.

In other words, in this gas interlock mechanism,
As mentioned above, the gas flow rate signal 13 flowing in the supply pipe B
is compared with the flow rate setting signal 16, and if there is a difference between the gas flow rate and the set flow rate value, the control signal 18 is output to correct the flow rate to the set value, and if an abnormality has occurred for some reason. , the difference between the set temperature (flow rate setting signal 18: absolute value V1) and the actual flow rate (flow rate signal 13: absolute value v2) cannot be corrected,
If the flow rate difference remains above a certain set value range (A), that is, if IV, -V21 >A, an alarm signal 20 is output to warn the outside.

[Problem that the invention seeks to solve]

However, in the case of the conventional apparatus configured as described above, in order to perform etching with high precision and even better reproducibility, it is necessary to not only change the gas flow rate as an operating condition.
A corresponding control circuit for each parameter, that is, a similar interlock mechanism must be provided.
Therefore, one plasma etching device requires a relatively large number of interlock mechanisms, which makes the overall configuration of the device itself and its control operations extremely complex, making it difficult and expensive to handle, and the sensor Abnormalities in the parts and control circuits are difficult to confirm, easy to overlook, and have various problems that are undesirable in practice, such as failure to obtain the desired effect.

The present invention was made to solve these conventional problems, and its purpose is to enable accurate detection of abnormal operation of the device using a single interlock mechanism. It is an object of the present invention to provide a manufacturing apparatus for this type of semiconductor device, in particular a plasma etching apparatus.

[Means for solving problems]

In order to achieve the above object, a semiconductor device manufacturing apparatus according to the present invention uses a plasma etching apparatus to directly control the change in the light emission state of gas plasma during etching operation, or to control the change in the light emitting state of gas plasma during an etching operation, or by controlling the change in the light emitting state of a gas plasma during an etching operation. It is equipped with a detection means that constantly monitors indirectly through reflection, etc., and a detection control means that compares the change in the light emission state of this gas plasma with a preset reference value, detects an abnormality, and outputs it. be.

[For production]

That is, in this invention, changes in the light emission state of gas plasma are constantly monitored during etching operations,
Since an abnormality is detected based on a change in the light emission state, a large number of operating condition parameters can be monitored and controlled very easily and effectively using only one set of detection means and detection control means.

〔Example〕

Hereinafter, one embodiment of the semiconductor device manufacturing apparatus according to the present invention will be described in detail with reference to FIGS. 1 to 4.

FIG. 1 is a configuration explanatory diagram schematically showing the outline of a plasma etching apparatus to which this embodiment is applied. In the configuration of the embodiment shown in FIG. shows the part.

That is, also in the configuration of the embodiment shown in FIG.
are upper and lower electrodes in the etching chamber la, and a semiconductor substrate 4 is placed and held on the lower electrode 3.

5 is an exhaust pipe for exhausting the inside of the etching chamber la, 6 is a supply pipe for supplying etching gas into the etching chamber la, and 7 is the upper part.

A high frequency power source connected to the lower electrode 2.3 by a conductive wire 8 and applying a high frequency voltage to the upper electrode 3; similarly, by applying this high frequency voltage, the supplied etching gas is turned into plasma, This plasma performs the desired etching.

A detection sensor 21 is located outside the chamber 1 and is used to constantly monitor changes in the state of plasma generated in the etching chamber la; The optical filter 22 for detection is a detection control circuit for comparing the detection signal obtained by the optical filter 21 with a preset reference value to detect an abnormality in the device. The photodetection signal detected by the optical filter 21 is transmitted to, for example, a phototransistor 23. Low pass filter 24. The detection voltage signal 26 obtained in this way is extracted as a voltage output through the voltage conversion circuit 25 and the reference voltage generation circuit 27.
A preset reference voltage signal 2 obtained from
8 by the comparator circuit 28, an abnormality in each operating condition parameter 6 during etching and an abnormality in the apparatus can be quickly, easily and effectively detected based on changes in the state of the plasma, and an alarm can be generated. signal 3
0. It is only necessary to output a control signal for correction as necessary, and in this way effective control can be achieved.

As you can see, FIGS. 2 to 5 each show the relationship of one change in the photodetection signal to the etching time when, for example, the polysilicon film of the semiconductor substrate 4 is etched by plasma reaction.

That is, when etching a polysilicon film with gas plasma using Freon gas in the above-mentioned embodiment apparatus, a plasma reaction of Si+↑→SiF+↑ (radical) occurs during etching, and Freon Radical (emission intensity within (704
nm) changes with time.

Therefore, by monitoring the state change of this plasma with the optical filter 21 and performing the above-described process, the second
The photodetection signal shown in the figure can be obtained.

The photodetection signal shown in Fig. 2 is extremely stable and highly reproducible under the same etching processing conditions. However, if due to some trouble, for example, the gas flow rate becomes higher than the set value, the photodetection signal will change significantly, as shown in Figure 3. It turns out.

Therefore, the photodetection signal in the normal plasma state shown in FIG. 2 is used as a reference signal and is outputted as the etching time progresses. value V) and the photodetection signal obtained by detecting the plasma state change at this time (detection voltage signal 26: absolute value V), and the value falls within a predetermined set value range (B ), it means that there is an abnormality in the device. That is, for example, when l V3-V41 >8, the comparison circuit 2e of the detection control circuit 22 outputs the alarm signal 30. What is necessary is to output a control signal for correction as necessary. In other words, this means that the detection voltage signal 28 detected as a photodetection signal is
If the signal waveform falls within the hatched range in FIG. 4, it means that no abnormality has occurred in the device.

In the configuration of the above embodiment, a case has been described in which changes in the light emission state of gas plasma during etching are directly monitored using an optical filter. An indirect means such as irradiating light and monitoring the reflected light may also be used, and similar actions and effects can be obtained. Further, in the embodiment, among the various processing conditions, only the abnormality in gas flow rate has been described, but it goes without saying that the present invention may be applied to detecting abnormalities in other pressure, temperature, RF power, and the like.

〔Effect of the invention〕

As described in detail above, according to the present invention, in a plasma etching apparatus, changes in the light emission state of gas plasma applied during etching operations can be directly observed.

Alternatively, abnormalities can be detected by comparing a detection means that constantly monitors indirectly by reflecting laser light emitted from the outside and changes in the light emission state detected by this detection means with a preset reference value. Since the configuration includes a detection control means for detecting and controlling a large number of operating condition parameters during etching processing, it is possible to monitor many operating condition parameters during etching processing very easily and effectively using only one set of detection means and detection control means. , it is possible to accurately detect and control abnormalities in the apparatus, and therefore, the control system of this type of etching apparatus can be constructed extremely simply, and the apparatus has the advantage of being easy to handle and operate.

[Brief explanation of drawings]

FIG. 1 is a structural explanatory diagram schematically showing the outline of plasma etching R1 to which an embodiment of the semiconductor device manufacturing apparatus according to the present invention is applied, and FIGS. FIG. 5 is a diagram schematically showing the configuration of a conventional plasma etching apparatus, and FIG. 6 is a diagram showing the gas interlock of the same apparatus. FIG. 2 is a configuration explanatory diagram showing an aspect of the mechanism. 1...Chamber, 1a...Etching chamber, 2
...Top electrode, 3...Bottom electrode, 4...Semiconductor substrate (object to be etched), 5...Exhaust pipe, 6
...Supply pipe, 7...High frequency power supply. 21... Optical filter (detection means), 22...
Detection control circuit (detection control means), 26...Detection voltage signal of plasma state, 2B...Reference voltage signal, 29
...Comparison signal, 30...Alarm signal. Agent Masuo Oiwa Fig. 2 Fig. 3 Fig. 4 Fig. 5 Enan 7” Procedural amendment to Fig. 7s6 (voluntary) Mr. Masuo Oiwa, Director General of Japan Patent Office, 1939, 3 Mi 1, Case Indication of Japanese Patent Application No. 62-57184 2, Name of the invention Semiconductor device manufacturing apparatus 3, Person making the amendment Representative Moriya Shiki 4, Agent 5, Subject of amendment (1) Detailed description of the invention in the specification Column 6, Contents of correction (1) "Upper electrode 3" on page 2, line 19 of the specification is corrected to "upper electrode 2." (2) "Comparison circuit 17" on page 3, line 16 of the same book is corrected to "comparison control circuit 17J." (3) "Upper electrode 3" on page 8, line 11 of the same book is corrected to "upper electrode 2".
” he corrected. (4) “Absolute value V” on page 11 lines 5-6 of the same book is changed to “absolute value V
Correct it with sJ. (5) Correct "absolute value V" in line 8 on the same page of the same book to "absolute value v4". (6) Delete "of the detection control circuit 22" in line 12 of the same page of the same book. (7) Make a j91c correction to Figure 1 of the drawing as a separate sheet. that's all

Claims (1)

[Claims] In a plasma etching apparatus, a detection means constantly monitors changes in the light emission state of gas plasma during etching operations, either directly or indirectly by reflection of externally irradiated laser light, etc.; 1. A semiconductor device manufacturing apparatus comprising: a detection control means for comparing the detected change in the light emitting state with a preset reference value to detect an abnormality.