JPS63211633A - Plasma etching device - Google Patents

Abstract

PURPOSE:To detect the time of the completion of etching of an article to be treated with high precision without being affected by the variation, etc., of luminous intensity by detecting luminous intensity by a detector, measuring the quantity of etching on the basis of the time integral value of the luminous intensity and detecting the time of the completion of etching. CONSTITUTION:A luminous intensity detector 13 detecting an optical wave-length in a vacuum chamber 1 is mounted onto the side surface of the vacuum chamber 1 through a filter 14, and an arithmetic circuit 15 conducting integral arithmetic operation on the basis of detected luminous intensity is connected to the detector 13. Accordingly, since the quantity of etching is measured on the basis of the time integral value of luminous intensity measured by the detector 13 and the arithmetic circuit 15 and the time of the completion of etching is detected, the method is not affected by the variation of luminous intensity as compared to the case when the time of the completion of etching is merely detected by the difference of luminous intensity, thus performing extremely accurate detection.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a plasma etching apparatus, and more particularly to a plasma etching apparatus that detects an etching end point based on the intensity of light emitted from plasma.

(Prior Art) In recent years, in the VLSI manufacturing process, when etching a film as a wiring material formed on a workpiece such as a semiconductor substrate, the workpiece with a predetermined resist applied on the film is etched. The resist film is fixed to an electrode in a vacuum container, high-frequency power is supplied to the electrode, and a process gas is introduced to generate glow discharge in the vacuum container, thereby etching the film other than the resist portion. There is.

The etching products gasified by the above-mentioned etching are excited in a high-frequency electric field and emit energy with a wavelength corresponding to that energy. It is possible to measure the increase and decrease of things. That is, conventionally, a luminescence intensity detection device for detecting the luminescence intensity has been provided in a vacuum chamber, and this luminescence intensity detection device detects the emission wavelength from the material to be etched during etching and the underlying material after all of the material to be etched has been processed. The end of the etching process is detected by detecting the difference in the wavelength of light emitted from the base material when exposed.

(Problems to be Solved by the Invention) However, in the above-mentioned conventional detection means at the end of the etching process, the emission intensity is, for example, l? When etching an alloy, there is a risk of fluctuations due to changes in film quality in the depth direction, generation of noise, etc., and etching detection errors occur, making it difficult to determine the end point. Moreover, in order to prevent the above-mentioned malfunction, careful adjustment of noise filters, measurement amplifiers, etc. is required, which requires a great deal of effort.

Furthermore, when a single material is etched and gas plasma of other materials is not generated, such as in silicon trench etching, there is no change in the emission intensity at the measurement wavelength, so it is not possible to detect the end of etching. The problem is that it cannot be done.

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a plasma etching apparatus that can detect the end of etching of a workpiece with high accuracy without being affected by fluctuations in luminescence intensity, etc. It is something.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, a plasma etching apparatus according to the present invention fixes a workpiece to an electrode disposed in a vacuum chamber, and applies high frequency power to the electrode. With,
In a plasma etching apparatus that etches the object to be processed by generating plasma discharge while introducing a process gas into the vacuum chamber, a light emission intensity detection method detects the light emission intensity of a wavelength generated from the gas plasma in the vacuum chamber. The device is provided with an arithmetic circuit that integrates the luminescence intensity detected by the luminescence intensity detection device over time and measures the amount of etching of the object to be processed based on the integrated value.

(Function) According to the present invention, the light emission intensity is detected by the detection device, and the amount of etching is measured based on the time-integrated value of this light emission intensity, and the end of etching is detected. Compared to the case where the end of etching is detected based on the difference in the luminescence intensity, this method is not affected by fluctuations in the luminescence intensity and can perform extremely accurate detection.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of a plasma etching apparatus for carrying out the present invention, in which an electrode 2 is disposed on the bottom surface of a vacuum chamber 1 with an insulator 3 interposed therebetween. An electrostatic chuck electrode 4 is adhered to the upper surface of the electrostatic chuck. A cooling water passage 5 is provided inside this electrode 2,
A cooling water introduction pipe 6 and a cooling water discharge pipe 7 are connected to the cooling water passage 5, respectively. Further, a large number of process gas ejection holes 8 are provided at a position facing the electrode 2 on one side of the vacuum chamber 1, and a process gas introduction pipe 9 is connected to the gas ejection holes 8. ing. A high frequency power source 11 is connected to the electrode 2 via a matching circuit 10, and a DC type [1
2 is connected, and the vacuum chamber 1 is grounded.

Further, on the side surface of the vacuum chamber 1, a vacuum chamber 1 is provided.
A light emission intensity detection device 13 for detecting the wavelength of light within is attached via a filter 14, and this detection device 13 includes an arithmetic circuit 1 that performs an integral calculation based on the detected light emission intensity.
5 is connected.

Furthermore, an exhaust port 16 connected to an evacuation device (not shown) is formed at the lower side of the vacuum chamber 1, and a heater 17 and a cooling pipe 18 are wound around the vacuum chamber 1, respectively. This allows the temperature of the vacuum chamber 1 to be controlled.

In this example, as shown in FIG. 2(a), Si
An oxide film 20 is formed on the substrate 19, and Al1- is formed on the surface of the oxide film 20.
A workpiece 23 on which Si21 has been deposited to a thickness of 1 μm and a predetermined photoresist pattern 22 formed on its upper surface is transported into the vacuum chamber 1, placed on the upper surface of the electrode 2, and a DC current is applied to the electrostatic chuck electrode 4. It is fixed electrostatically by applying a DC voltage from the power source 12. In this state, the inside of the vacuum chamber 1 is evacuated from the exhaust port 16, and the gas introduction pipe 9
While introducing the process gas sent from the wafer into the vacuum chamber 1 at a predetermined pressure through the gas ejection hole 8, high frequency power is applied from the high frequency power source 11 to generate plasma discharge, thereby etching the object 23 to be processed. The above etching is
As shown in FIG. 2(a), this is done by etching the portions of Al1-8L21 where the resist pattern 22 is not applied, and as shown in FIG. 2(b), the Aj
The etching ends when all of the l-Si 21 is processed and the oxide film 20 is exposed.

Figure 3 shows the principle of determining the amount of etching by the emission intensity detection device 13 in this embodiment, and shows the case where the emission intensity is detected by measuring the wavelength of 396 nm with emission from one excited state of Ag. ing. In Figure 3(a),
A is the background from other wavelengths, as shown in Figure 3 (
In b), B is the wavelength of 396 nm of Ag, and C is the intensity of Si emission from the oxide film. First, the actual etching amount (
R) M1 is divided by the integral value 11 of the luminescence intensity detected in FIG. 3(b), that is, the etching amount ΔM for a unit luminescence intensity integral value is determined. Next, the relationship between the etching amount M of the unknown object to be processed and the luminescence intensity IR1 time T is determined using the following equation.

M-ΣIRxΔTR×ΔM 6M-M1/, E I, XΔT1 According to the above formula, when etching the object to be processed, the etching mm is calculated by an arithmetic circuit, and the end of the etching process is detected based on this etching mm. .

In addition, if a single material is etched by trench etching, etc., and there is no change in the emission intensity, see Figure 3 (c).
), the amount of etching can be detected by calculating the area of light emitted from Afl.

Figure 4 shows the correspondence between the amount of etching and the luminescence intensity. First, as shown in Figure 4(a), at the start of etching, the luminescence intensity rises slowly due to the influence of surface oxides and reaches a steady state. becomes. During etching, the emission intensity hardly changes (Fig. 4(b)), and as the etching approaches the end and the oxide film 20 of the base material is exposed, the emission intensity decreases, and instead, the oxide film 20 is exposed. The luminescence intensity of 20 increases (FIG. 4(C)). Completely Al1-Si2
1 is removed, the emission intensity of the oxide film 20 becomes steady (FIG. 4(d)).

Therefore, in this example, the luminescence intensity is detected,
Since the amount of etching is measured based on the time-integrated value of the luminescence intensity and the end of etching is detected, fluctuations in the luminescence intensity are detected compared to simply detecting the end of etching based on the difference in luminescence intensity. Not affected by
Extremely accurate detection can be performed.

〔Effect of the invention〕

As described above, the plasma etching apparatus according to the present invention is provided with a luminescence intensity detection device for detecting the luminescence intensity of a wavelength generated from gas plasma in a vacuum chamber, and a luminescence intensity detection device that detects the luminescence intensity of the wavelength generated from the gas plasma. is provided with an arithmetic circuit that integrates over time and measures the amount of etching of the object to be processed based on the integrated value, and measures the amount of etching based on the time-integrated value of the luminescence intensity measured by the detection device and the arithmetic circuit; Since the end of etching is detected, compared to simply detecting the end of etching based on the difference in emitted light intensity, it is not affected by fluctuations in emitted light intensity and can perform extremely accurate detection. be effective.

[Brief explanation of the drawing]

1 to 4 each show an embodiment of the present invention, in which FIG. 1 is a configuration diagram of a plasma etching apparatus, FIGS. 2(a) and 2(b) are illustrations of etching, and FIG. Figure 3 (a), (b) + (c) are diagrams showing the relationship between luminescence intensity and time, Figure 4 (a), (b),
(c) and (d) are explanatory diagrams showing the relationship between the etching state of the object to be processed and the luminescence intensity, respectively. DESCRIPTION OF SYMBOLS 1... Vacuum chamber, 2... Electrode, 4... Electrostatic chuck electrode, 8... Gas injection hole, 9... Gas introduction tube, 13... Emission intensity detection device, 15. ...Arithmetic circuit, 20...Oxide film, 21...Al-5t, 22...
-Resist pattern, 23... object to be processed. Applicant's agent Sato - Yu time 8 temples Ma 8 temples Mae 3 time 19' (b) θ (C)

Claims (1)

[Claims] The object to be processed is fixed to an electrode placed in a vacuum chamber,
In a plasma etching apparatus that etches the object to be processed by applying high-frequency power to the electrode and generating plasma discharge while introducing a process gas into the vacuum chamber, the plasma etching device generates plasma from the gas plasma in the vacuum chamber. A light emission intensity detection device for detecting the light emission intensity of a wavelength is provided, and an arithmetic circuit is provided for integrating the light emission intensity detected by the light emission intensity detection device over time and measuring the amount of etching of the object to be processed based on the integrated value. A plasma etching device characterized by: