JPS6245119A - Dry etching device - Google Patents

Abstract

PURPOSE:To detect the intensity of an emission spectrum from a CO molecule before and after the completion of etching, and to detect the end point of etching precisely by monitoring the intensity of a plasma emission spectrum between a second electrode, from which a polymer is hardly formed, and an intermediate electrode. CONSTITUTION:A material 17 to be processed is manufactured in such a manner that a thermal oxide film (an SiO2 film) is formed on an Si substrate in 5,000Angstrom , and a resist pattern is shaped onto the thermal oxide film. The state of the etching of the material 17 is detected by an etching monitor 19 through a silica glass 18. Accordingly, the luminescent intensity of a CO molecule having a wavelength of 519.8nm suddenly increased by the generation of plasma with the application of high-frequency power as shown in a graph, a fixed level is maintained, and luminescent intensity after approximately fifty sec after the application of high frequency begins to reduce, and reaches predetermined intensity at a comparatively low level after approximately sixty sec after the application of high-frequency power. The etching of SiO2 is completed at that time.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a dry etching apparatus used in the manufacture of semiconductor devices, and more particularly to monitoring the progress and end point of etching of silicon oxide films and the like.

Conventional technology In recent years, mass spectrometry, probe method, and spectroscopic analysis have been considered as methods for monitoring dry etching, but these methods are easy to attach to the equipment and do not change the plasma state. Therefore, spectroscopic analysis has become mainstream.

An example of a conventional dry etching monitoring device will be described below with reference to the drawings.

In FIG. 6, 1 is a vacuum chamber, 2 is an upper electrode, 3 is a lower electrode, 04 is a gas inlet, and 6 is a gas exhaust port.

6 is a workpiece, 7 is quartz glass, and 8 is an etching monitor.

One method of monitoring using spectroscopic analysis is to use the upper electrode 2 and the workpiece 6.
The end point of etching is controlled by detecting the characteristic change in the intensity of the emission spectrum during etching between the lower electrodes 3 on which etching is placed.

This spectroscopic analysis method is also used as a method for dry etching monitoring of silicon oxide films (hereinafter referred to as SiO2).

Problems to be Solved by the Invention However, the etching gas used for dry etching the S102 film, for example, CHF3°CF+CHF
3. C2F6+CHF3. When etching is performed using C3F8+CHF3, etc., F, C
o, Co2. COF Toi-) Daikoya Molecule 75E
Although each emission spectrum is detected, the change in the emission spectrum is extremely small even after etching is completed, that is, when the Si film underlying Sio2 is exposed. The emission spectrum of the 00 molecule, which has a strong emission intensity, is supposed to decrease in intensity when etching is completed, but when actually measured, almost no change in intensity is observed. This is thought to be because the polymer produced during etching with the etching gas has some oxygen chemically bonded to it, and Co molecules continue to emanate from this polymer even after etching is completed. For this reason, there was a problem in that it was difficult to monitor by emission spectroscopy before and after the etching was completed.

In view of the above problems, the present invention monitors only the 00 molecules generated by the chemical reaction when etching Sio2 with fluorocarbon and fluorohydrocarbon gases, and monitors only the 00 molecules generated from the polymer generated during etching. provides a dry etching apparatus using a method of dry etching monitoring without monitoring.

Means for Solving the Problems In order to solve the above problems, the SiO2 dry etching apparatus of the present invention has a structure in which a workpiece is placed between the first electrode and the second electrode opposite thereto. An air permeable intermediate electrode is provided, plasma is generated between the intermediate electrode and first and second electrodes, and only the plasma emission spectrum generated between the intermediate electrode and the second electrode is monitored.

Effect: Due to the above-described configuration, the present invention has the feature that during etching, the production of polymers is concentrated between the first electrode and the intermediate electrode, and almost no polymers are produced between the second electrode and the intermediate electrode. It uses

That is, on the monitor side, since no 00 molecules are generated from the polymer at the end of etching, the emission intensity of Co molecules changes greatly before and after the end of etching the SiO□ film, so the end point of etching can be accurately detected.

EXAMPLE Hereinafter, a dry etching apparatus according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of a dry etching apparatus according to an embodiment of the present invention.

In FIG. 1, 9 is a vacuum chamber, 1o is an upper electrode, 11 is a lower electrode, 12 is an air-permeable intermediate electrode, and 13 is a vacuum chamber.
14 is a high frequency power supply, 15 is a gas inlet, 16 is a gas exhaust port, 17 is a workpiece, 18 is quartz glass, and 19 is an etching monitor equipped with a spectroscopic analysis function. 18
The quartz glass is placed between the upper electrode 1o and the intermediate electrode 11.The operation thereof will be explained below using FIG. 1.

First, the workpiece 17 is a thermal oxide film (S 1
02 film) was formed by 5,000 people, and a resist pattern was formed thereon. In the present invention, a mixed gas of 02F620sccm and CHCHF330sc is used for this SiO film, and the lower electrode 11 is y6oW.

30oW was applied to the upper electrode 9, and the pressure inside the chamber was increased to 5.
Etching was performed at 00 mTorr. Then, the etching state was detected by an etching monitor 19 through a quartz glass 18. The results are shown in FIG. The wavelength of the detected emission spectrum of 00 molecules is 519.8 membrane m.
It is. As shown in Figure 2, from the plasma generation tail due to the application of high frequency power, the wavelength of 1519.8 m
The luminescence intensity of 00 molecules increases rapidly, remains at a constant level, then begins to decrease approximately 60 seconds after high-frequency power is applied, and reaches a constant level at a relatively low level approximately 60 seconds after high-frequency power is applied. Become. At this point, the etching of 9102 is completed. After approximately 10 seconds, the application of high-frequency power is stopped, and after etching is complete, the resist is removed and the level difference between the etched area and the etched area is measured using a level difference meter (Ten-Niel α).
As a result of measurement using STEM 200), the height difference was approximately 5,100, and it was confirmed that the SIO2 film was completely etched.

In FIG. 2, A is the time point when high frequency power is applied, B is the time point when etching is finished, and C is the time point when high frequency power is stopped.

Note that the SiO2 film was heated to 50oO as in the above example.
People Perform dry etching and use a wavelength of 500 nm or C.
) 62! Changes before and after the etching end point up to 5 nm were investigated. FIG. 3 shows the wavelength after 3 seconds of Si○2 film etching. The etching has also been completed7
The wavelength after 0 seconds is shown in FIG. 4 on the same scale as FIG. 3.

As can be seen by comparing Figures 3 and 4, the wavelength is 519.8.
C of film m, 561.0 film m, 608, Onm
○The strength and weakness of the molecular spectrum were clearly seen. From this, it can be seen that the wavelength of Co molecules other than the first example is 561. ○nm
608, it is also possible that Onm is being detected.

Although the dry etching of an SiO2 film has been described above, the present invention can also be applied to etching of other workpieces that generate polymers or to etching conditions that do not generate polymers at all.

Effects of the Invention As described above, the present invention monitors the intensity of the plasma emission spectrum between the second electrode and the intermediate electrode, where less polymer is produced, thereby reducing the influence of 00 molecules emanating from the polymer produced during etching. Since the intensity of the emission spectrum of the 00 molecule before and after the end of etching can be detected without being affected, the etching state can be accurately grasped and the correct end point of etching can be detected.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a dry etching apparatus according to an embodiment of the present invention, and FIG. 2 is a diagram showing Co molecule emission intensity and etching at a wavelength of 519.8 m, measured by a dry etching monitoring method applied to the present invention. A graph showing the relationship between time and FIG. 3 is a cross-sectional view of a conventional dry etching apparatus according to the present invention. ... lower electrode, 12 ... middle electrode, 13.14 ... high frequency power supply, 17 ... workpiece, 19 ... etching monitor. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure q-actual character ya 2, ・- iO-- yoif bowmangu 3≦ihi 1f--7 to P-- 12--9...+3. ＋4-Even broken power source 71--Strict force σ work Tw q--Ennan quart f″? Fig. 2 Fig. 3 Scroll & tnm) Fig. 4 Temperature tnm) Fig. 5

Claims (2)

[Claims] (1) A reaction vessel includes a first electrode and a second electrode opposing the first electrode, a workpiece is placed on the first electrode, and the first electrode and the second electrode are connected to each other. an intermediate electrode having air permeability is provided between the electrodes, and means for generating plasma by applying high frequency power to one or both of the first electrode and the second electrode; A dry etching apparatus equipped with an etching monitor for monitoring an etching state by monitoring intensity changes in an emission spectrum generated between the intermediate electrode and the intermediate electrode. (2) The dry etching apparatus according to claim 1, wherein the workpiece is a silicon oxide film and the emission spectrum of CO excited molecules is used as the emission spectrum.