JPH0797574B2 - Process control method for plasma processing - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a process control method for plasma processing, and more particularly to a process control method for plasma processing suitable for controlling the plasma processing rate.

[Conventional technology]

As a conventional plasma treatment, for example, as disclosed in Japanese Patent Application Laid-Open No. 60-98631, there is one that observes a change in generated intensity to determine the end of the treatment, which is useful for automating the plasma treatment.

[Problems to be solved by the invention]

In recent years, in order to improve the reliability and productivity of the production process, not only mere automation but also management of the production process itself is required. In the plasma processing apparatus, it is a well-known technique to detect the end of processing from the time change of plasma emission intensity. This utilizes the fact that the intensity of light of a specific wavelength changes during and after processing. At that time, for example, in an etching apparatus, variations in etching rate within a sample, and in the case of a so-called batch type apparatus that simultaneously processes a large number of samples, variations in etching rate between samples may cause The change in light emission intensity will be gentle. These variations in the etching rate appear as influences on the underlying film and variations in the cross-sectional shape of the film to be etched. In the semiconductor integrated circuit manufacturing process,
It has become an important factor.

The above-mentioned conventional technology is useful for determining the end of plasma processing and automating to the next processing, but no consideration is given to extracting other information obtained by observing the generation intensity and using it for process control. Therefore, there is a problem that the process management function cannot be supported.

An object of the present invention is to improve the reliability and productivity of the plasma processing apparatus by detecting the non-uniformity of the plasma processing speed and instructing the subsequent plasma processing process as one of the process management functions. Another object of the present invention is to provide a process control method for plasma processing that can achieve the above.

[Means for solving problems]

The above-mentioned purpose is a step of detecting the emission intensity of a specific wavelength of plasma treatment plasma, a step of analyzing the intensity change of the emission detected in the step, a step of measuring the time when the emission intensity changes, and etching in the step. The time (t1) from the start of etching to the start of etching and the time (t2) required from the start of etching to the end of etching are detected, and the processing speed Comparing the length of the non-uniform time (t2-t1) with a preset value to judge the non-uniformity of the processing speed; and the step of giving an instruction to the next plasma processing process by the judgment of the step. Is achieved by having

[Action]

From the change in the emission intensity of the plasma processing, the beginning and end of the processing end period are detected, the time is measured to detect the non-uniformity of the processing speed, the operation of the plasma processing apparatus is stopped, and further processing conditions are Can be changed to improve the reliability of the plasma processing apparatus and improve the productivity.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1, 3, and 4.

FIG. 3 shows an example of a device configuration for carrying out the present invention.

In this case, an etching process is shown as the plasma process, and the state of the etching process is performed by detecting a specific wavelength in the light emission of the plasma. 7, a light emission detector 8 and an arithmetic unit 9. There are various types of etching apparatuses, such as a barrel type, a parallel plate type, and a microwave excitation type, depending on the plasma generation method, but the type is not limited in the present invention.

When etching is started, the emission intensity of a desired wavelength is detected by the emission detector 8, the end of processing is detected and analyzed by the arithmetic unit 9, and the result is fed back to the control unit 7.

FIG. 1 shows the change in emission intensity when plasma treatment is performed. In FIG. 1, the curve 1 shows the time variation of the specific wavelength in the emission of plasma. The wavelength in this case indicates a specific wavelength of the light emission of the substance generated by the reaction between the substance to be etched and the reaction gas. When the discharge is started at A, the reaction product is generated and the emission intensity is high. Become. In B, the emission intensity begins to decrease when a part of the substance to be etched begins to be removed, and in C, it is shown that the treatment of all the substance to be etched is completed.

Time lag between Thus B and C, t ₂ -t ₁ is due to non-uniformity of processing of the material to be etched. Here, t ₁ is the time required from the time A when the etching is started to the point B when the etching is started, and t ₂ is the time required from the point A to the point C when the etching is ended. . The time measurement start time does not have to be the etching start time. If this non-uniformity is large, the so-called over-etching time from when the substance to be etched is removed to when the discharge is stopped varies greatly depending on the location in the sample. There is an important influence on the device characteristics such as the progress of side etching.

Naturally, it is also important to develop processing conditions that reduce this non-uniformity, but non-uniformity is detected for each process,
Managing is also important.

As a method for detecting this non-uniformity, a second-order difference (second-order differential) of the emission intensity curve 1 as shown by the curve 2 is obtained.
By obtaining the next difference curve 2 and examining the inflection point, the beginning B and the end C of the end period of the treatment of the substance to be etched are obtained.
Is being detected. The process after detecting the nonuniformity in this way is shown in the flowchart of FIG.

In this case, the plasma treatment was completed 10, based on the times t ₁ and t ₂ measured during the plasma treatment, the length t ₂ −t ₁ of the non-uniform processing speed was compared with the set value. 11, when the value of t ₂ -t ₁ exceeds a predetermined value, outputs the fact message to the operator 12 stops the continuation of the processing of the next 13. On the other hand, if the value of t ₂ -t ₁ is within the set value, to continue the process 14.

As another method for setting the judgment condition, for example, t ₁ / (t ₂ −t
It is also possible to compare the value of ₁ ) or t ₂ / (t ₂ −t ₁ ) with the set value.

As described above, according to the present embodiment, since the non-uniform portion of the plasma processing speed can be detected from the emission intensity during the plasma processing, it is decided how to perform the subsequent plasma processing, and the reliability of the plasma processing apparatus is improved. There is an effect that can improve.

Further, in this embodiment, when the value of t ₂ -t ₁ does not exceed the set value has been to stop the continuation of treatment, be a command for issuing an instruction to correct the appropriate processing conditions It is also possible to automatically change the processing conditions and continue the processing without stopping the apparatus, and it is possible to improve the productivity.

Further, in the present embodiment, the determination of the non-uniformity of the processing speed is
Although it is carried out inside the apparatus composed of the etching apparatus main body 6, the control apparatus 7, the light emission detector 8 and the arithmetic unit 9, the host computer of the semiconductor device manufacturing line connected to the host computer determines each manufacturing apparatus. Is also good. As a result, since process control can be performed on the semiconductor device manufacturing line, it is possible to contribute to automation of the manufacturing process and production control.

Next, another embodiment of the present invention will be described with reference to FIG.

FIG. 2 is a diagram showing a change in emission intensity when plasma treatment is performed. In this case, when the wavelength corresponds to the emission from the reaction gas as a monitor wavelength for detecting the end point of the treatment. Shows an example of.

In this case, when the discharge is started at A ', the reaction gas is consumed for the reaction with the substance to be etched, so that the emission intensity is low, and when the substance to be etched is partially removed at B', the emission intensity is gradually increased and C is increased. The emission intensity becomes maximum when all are removed by ′. Also in this case, the same processing as in the above-described embodiment can be performed by obtaining the quadratic difference curve 4 which is the quadratic difference (second derivative) of the emission intensity curve 3.

As described above, according to the other embodiment, the same effect as that of the one embodiment can be obtained.

〔The invention's effect〕

According to the present invention, the non-uniformity of the plasma processing rate is detected,
Since the next plasma processing process can be instructed, there is an effect that the reliability of the plasma processing apparatus can be improved and the productivity can be improved.

[Brief description of drawings]

FIG. 1 and FIG. 2 are diagrams showing the time variation of plasma emission intensity in the process control method of plasma treatment according to the embodiment of the present invention, and FIG. 3 is the entire apparatus for observing FIG. 1 and FIG. FIG. 4 is a flow chart showing the processing of FIG. 1 and FIG. 1,3 ... Emission intensity curve, 2,4 ... Second-order difference curve, 6 ... Etching device body, 7 ... Control device, 8 ... Emission detector, 9 ... Computing device

Claims (1)

[Claims] 1. A step of detecting an emission intensity of a specific wavelength of a plasma while plasma processing, a step of analyzing a change in emission intensity detected in the step and measuring a time when the emission intensity changes, The time (t1) from the time when the etching is started to the time when the etching is started and the time (t2) required from the time when the etching is started to the time when the etching is ended are detected, and the processing is performed. A step of comparing the length of time of non-uniformity of speed (t2-t1) with a preset value to judge the non-uniformity of the processing speed, and giving an instruction to the subsequent plasma processing process by the judgment of the step. And a process control method for plasma treatment.