JPS5923519A - Monitoring apparatus for etching - Google Patents

Abstract

PURPOSE:To detect end of plasma etching automatically at high accuracy, by a method wherein when films of different quality in plural layers are subjected to plasma etching, photoelectric conversion elements to convert luminous spectrum of different wavelength from plasma into electric signal and a feedback circuit to feed back the electric signal to the element are provided. CONSTITUTION:Spectrophotoelectric conversion elements 13A and 13B to perform spectroscopic processing to only specific wave length inherent to the etching film of an SiO2, SiO3O4 or the like and to convert it into electric signal are attached to a side wall of a reaction chamber 1. These elements are connected through amplifiers 14A and 14B to a monitoring control device 15, which is connected to a control device 8 for a high-frequency oscillator and also to the elements 13A and 13B through a feedback circuit 16. Within the reaction chamber 1 in such constitution, an upper electrode 2 and a lower electrode 3 to hold an etching spectrum 6 thereon are opposed and luminous spectrum 12 produced between the electrodes by the high-frequency oscillator is detected by the elements 13A and 13B and the monitoring is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a monitoring device for plasma etching, and more particularly to an etching monitoring device for detecting the end point of etching a plurality of layers of different films on the surface of a semiconductor substrate during the manufacturing process of a semiconductor device.

In recent years, in this type of plasma etching, only one
In some cases, it is required to form not only a layered etching film but also a plurality of layers such as two or three layers of different film quality. In such cases, it is necessary to use light waves with different wavelengths for each film quality. For example 5102
For the purpose of etching the film, 5ilN and K must use light with a wavelength of 519 nm for the former and 674 nm for the latter.

However, in conventional plasma etching equipment,
Since the spectroscopy of the optical spectrum is performed using a filter, it is not possible to reduce the wavelength conversion due to the progress of etching, and it has been possible to monitor only one of the films. An example of this type of device light is i
-1, as shown in Figure 1. In this apparatus, 1t is the reaction vessel, 2 is the upper 'tJL pole, and 3 is the lower 1t
random pole, 4 is a reaction gas inlet, 5iJ: a reaction gas inlet, 6 is a sample to be etched, 7 is a high-frequency oscillator, 8 is a control 41 device for 7, 9 is a spectroscopic/Kutun conversion device, 10i-j is an amplifier, 1li-t, performance 3γ circuit, 12. It is an emission spectrum from plasma in reaction vessel 1. In the apparatus shown in FIG. 1, the 9゛0 spectrum 12 emitted from the plasma is sent to the spectrometer to power converter σ9, and only the light of a fixed wavelength is converted to an electrical signal, and the 900 spectrum 12 is sent to the amplifier 10. It was expanded to the village of Tekken and performed there.

The etching end point sound is detected in circuit 11, and the signal? The signal is input to the control device f8 of the high frequency oscillator 7. However, the spectroscopy/light conversion device 9 of this conventional device only has one spectrometry/light conversion device? iI
It has only a conversion element and can only monitor one film.

However, another conventional method uses a gold spectrometer to analyze the emission spectrum from plasma. However,
In this case, it is necessary to manually convert the selected wavelength r of the device as the etching progresses, which has the disadvantage that the operation is troublesome and that the wavelength selection error is also poor.

The purpose of the present invention is to overcome the drawbacks of the prior art and to improve the etching end point of a multi-layered heterogeneous film. We are developing an etching monitoring device that can automatically detect with good clarity and improve wavelength selection accuracy.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in detail below according to embodiments shown in the drawings.

FIG. 2 is a schematic diagram of an embodiment of the etching monitor 1 non-gating device according to the present invention.

In this embodiment, a plurality of spectroscopic/photoelectric conversion elements 13A and 13B are provided on the side wall of the reaction vessel 1.

These spectroscopic/photoelectric conversion elements 13A and 13Bi-1 each have a specific wavelength unique to the etched film formed, for example, 519 nm in the case of 5TOZlIA, 519 nm in the case of 5lBN
In the case of '411, only the light of 674 nm is subjected to spectroscopy, and only the )'C thereof is converted into a total thi signal. Each spectroscopic/optical fi
The l conversion elements 13A, 13B are connected to amplifiers 14A, 14B at iL.

Both amplifiers 14A and 14B are connected to a control device 15 for monitoring control.

The control device fi'it: 15 is connected to the control device 8 for the high frequency oscillator, and is also connected to the feedback circuit 10' (l: via both spectroscopic and optical i1'c conversion elements 13A and 13B.

Next, the operation of this embodiment will be explained.

Plasma is generated between the upper electrode 2 and the lower electrode 3 in the F reaction vessel 1 when high frequency sound is applied to the lower electrode 3 by the high frequency light station device 7. The emission spectrum 12 from this plasma is separated by spectroscopic/optical seven-part conversion elements 13A and 13F, and only the source of the specific wavelength is converted into a signal. For example, when performing two-layer etching of the 5102 film and SSi3N4JI, the S to2 film is first etched, so at that time, the single photoconductor conversion element 13AV is separated.
cJ: Monitoring is performed at a light wavelength of 519 nm.

Sin, when the film etching is completed, it is followed by f
[5r) Start heating the spectroscopic/temperature conversion element 13B for monitoring film etching at 513 N using the rectangular V-tube 15. Along with this,
Controlled dust 1 (day 13 with a light wavelength of 9,15k1674nm)
Monitor the etching of the N4 film.

In other words, the above-mentioned YS conversion elements 13A, 13
In each of the 13 spectroscopy formulas, only the constant wavelength of 1'0) was constructed to convert into electricity. After 14E', the signal is incremented 11j and then transmitted to the control device 15, where it is displayed on the monitor 1.

When the etching process of the 102 membrane is completed, the control device 15 sends an electrical signal to the optical IE converter 3B as described above. Si, IJ at an optical wavelength of 674n+n with a fF movement start of 7.
, perform 7 monitoring of JIQ etching.

In this way, following the 5102 membrane), the 813N4
II! When the etching end point of i% is detected, fli
ll i)'Ill'J°L15tYU Suppression-1AIA
Transmits a signal sound to I', 8, and transmits a signal sound to: Ijl) Deposit 11 device i:
le high frequency oscillation stone in le 8, 7? To cape.

Therefore, in this example, two layers of heterogeneous materials formed by etching are used.
? (63-3N, Etching of Exhibit 1 is automatically monitored sequentially and continuously, and the wavelength selection accuracy of the 6 films is also good.

FIG. 3 shows another embodiment of the invention.

In this example, the plasma has different wavelengths.
Spectrum ke spectroscopy device and source? ! - Spectroscopy/light conversion device that converts into electrical signals [conversion element 1]
Only one 7 is provided. This spectroscopic/photoelectric conversion element 17 is connected to a control device 19 via an intensifier 18. The control device 19 is connected to the control device 8 for the high frequency oscillator 7, and transmits a signal for selecting a predetermined wavelength for the film to be etched to the spectroscopic/optical conversion element 17.
It is connected to a circuit 20 for transmitting data to the.

In addition, in this embodiment, a laser beam generator (light emitting device) 21 is provided on the i1u wall of the reaction vessel 1, facing the above-mentioned component-X-element 1 square conversion element 17 and F on the opposite side. .

This laser beam generator R21f"j: Helium (I(G
) - Neon (Ne) laser t (tentative tJJ1. length = 6
32.8 Nm) g The light passes through the plasma and irradiates the spectroscopic/optical 11 conversion element 17, and the rotation angle of the spectroscopic device in the element 17 is corrected to improve the wavelength selection Y of the spectroscopic device. This laser beam generator 21i-j circuit 22i valve is connected to the control device 19. L5 control device 1
The operation is fully controlled by 9.

According to this embodiment, this is the same as in the previous embodiment ( ):
When performing two-layer film etching of 1-j', the first 51
When etching the 02 film, a signal from the control device 19 is transmitted through a circuit 20' to 17 spectroscopic/photoelectric conversion elements, and a signal having a wavelength of 519 nm is selected.

When the etching of the 5102 film is completed, a signal is transmitted via the spectroscopic/photoelectric conversion element 17 and the intensifier 1↑J device 18 to the control device 19, and the control device 19μs 1.1i.

A selective signal with a light wavelength of 674 nm for monitoring the etching of the film is transmitted to the spectroscopic/photoelectric conversion element 17 via all 20 circuits. In this No. 18, in the spectroscopic/photoelectric conversion element 17, the rotation angle of the diffraction grating is controlled 9111 by rotating the drive motor of the spectrometer. At this time, if the laser beam c with a wavelength of 632.8 Nm from the laser beam generator 21 is irradiated onto the φ light πL conversion element 1.7, and the rotation angle of the spectrometer is corrected, the accuracy of the rotation angle of the spectrometer is This improves wavelength selection (!<accuracy) of spectrometers.

In this example as well, the etching end point of the two-layer film of 81o2 film and 813N4 film is detected automatically, and monitoring at a light wavelength suitable for etching both films is performed.
ff can be performed with good accuracy.

-! , and connected to the control device and all monitoring devices of the plasma etching apparatus ff itself on both the actual flow sides,
If the etching monitoring detection signal controls the introduction and exhaust of the reaction gas and the operation of the control V+II device for the high-frequency imaging device, it is possible to fully automate the etching process, increasing work efficiency, Labor saving is possible.

Incidentally, in the above embodiment, an example of forming a 21 film of 5to27 film and 5LsN4 film was explained, but in addition to that, 5to27 film and 51sNt) J! 5102 membrane and Bo IJ s
The present invention can be easily applied to a single three-layer film, etc.

As explained above, according to the present invention, ψ%5 of multiple layers
Etching end point of ¥ film? automatically! 'C can be detected with high accuracy, and the wavelength selection wavelength can be improved.

1''1i'1lit H section in Figure 1 is an illustration of a conventional device; Figure 2 is an explanatory diagram of an embodiment of an etching monitoring device according to the present invention; FIG. 6 is an explanatory diagram of another embodiment of the present invention.

1... Reaction container, 2... Dobe electrode, 3... Lower part η
°C pole, 6... Sample to be etched, 7... High frequency oscillator C (, 12... Emission spectrum, 13A, 13B
... Spectroscopic/photoelectric conversion element, 15... Control device, 17
. . . Distributor/light conversion element, 19 . . . fltlJ control, 20 .

Figure 1 Figure 2

Claims (1)

[Scope of Claims] (1) A monitoring device is installed to completely check the etching end point of a heterogeneous film of several layers formed during plasma etching, and a monitoring device is installed to monitor the light spectrum of different wavelengths emitted from the plasma. ? +1: Multiple iv to convert to Kihakugo
aO original t? Transmits the TIL signal from the control device to all the optical ttt conversion elements. Monitoring device for etching to detect the etching end point sound of multiple layers of heterogeneity formed during plasma etching. In the equipment, the wavelengths emitted from the plasma are different)
The spectrometer fl'7゜ which distributes the ゛c spectrum and the source 1
(T) a photoelectric conversion device that converts it into a gas signal, a control device that operates the front helium splitter to switch the wavelength as the device gold etching progresses, and a control device that activates emitted specific wavelengths to increase the wavelength resolution accuracy of the spectrometer. A total improvement of the light emitting device i't, and a monitoring device for etching with KLR features.