JPH03177587A - Plasma treatment method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a plasma processing method.

[Prior Art] As the miniaturization of semiconductor devices progresses, their structures become three-dimensional, and 0.3 μrlLf devices require high step etching with an aspect ratio of 5 or more.

Figure 4 is a diagram showing the state of conventional plasma etching of a flat pattern, where (a) shows the pattern shape, (b) shows the temporal change in emission intensity, and (c) shows the changes in plasma parameters such as pressure and etching gas flow rate. It shows the change over time. (a
) indicates a just-etched state; however, there is some non-uniform etching within the shell, which necessitates over-etching, and the change in emission intensity is as shown in (b). In this case, the parameters are etched in one step as shown in (C), or in the case of over-etching, two-step etching is performed in which the parameters are changed.

[N problems that the invention attempts to solve]

However, in the case of a high step pattern with a large aspect ratio as shown in Fig. 2, the vertical thickness of the etched material 2' differs significantly between the flat part and the step part, and the emission intensity during etching is as shown in Fig. 2. As shown in (b), during overetching, the etching begins to descend in a gentle curve.

Therefore, over-etching takes time and sufficient etching characteristics cannot be obtained with conventional one-step etching or two-step etching. l! There is an issue.

An object of the present invention is to obtain excellent etching characteristics even when processing patterns having such high step differences.

Means for Solving Problem C] In order to achieve the above object, in the present invention, as shown in FIG. It is designed to be controlled in a controlled manner.

[For production]

By continuously controlling the parameters, it is possible to continuously form plasma that corresponds to changes in the area to be etched, so that patterns with high steps can be processed with good characteristics.

〔Example〕

The present invention will be explained in detail by examples. FIG. 1 shows a configuration diagram of an etching device to illustrate one embodiment of the present invention, in which a waveguide 5. Discharge tube 6. A solenoid coil 7, a t-pole 9 on which a wafer 8 is placed and connected to an RFQ source 1o. Consists of a vacuum chamber 11,
Light receiving aL2. which receives plasma light emission. Controller 1
3 controls the mass flow controller of the etching gas 14 in this embodiment to supply the etching gas into the processing chamber.

Therefore, the controller 3 is capable of continuously controlling the flow of the etching gas according to changes in the emission intensity in the plasma.

FIG. 3 shows the etching characteristics of the M-based wiring material in the etching apparatus constructed as described above, in comparison with the results of conventional one-stage etching (FIG. 5).

In FIGS. 3 and 5, (1) is the etch area.

(b) shows the etching gas flow rate, and (C) shows the time dependence of the etching rate.

In conventional etching, one-stage etching is performed, so there is excess etching gas during over-etching.
Along with this, the effect of drawing out the C component in the photoresist becomes stronger, and the etching rate of the photoresist increases. On the other hand, the etching rate of M is usually performed at a location where there is little dependence on the flow rate, and there is no large change. Therefore, the selection ratio of M to the photoresist deteriorates, causing the photoresist to fall off and the pattern becoming thinner.

Regarding the base material 5L02, ion irradiation is rate-determining and no significant difference is observed.

In contrast, in this embodiment, the etching gases tM and IIk are reduced as the etching area is reduced, so that optimal plasma is generated every moment, and even in overetching, the etching rate of the photoresist can be maintained at a low level. I can do it.

As described above, according to this embodiment, the selectivity with respect to the photoresist during over-etching in high-step etching can be significantly improved, and the thinning of the dimension due to the drop-off of the photoresist is eliminated, and fine lines such as 0.3 μm can be formed. Processing becomes possible.

Plasma parameters are not limited to the above-mentioned etching gas flow rate, but include shape controllability, substrate 5
Pressure and RF bias voltage may be controlled for selectivity with i02 and residue controllability.

Further, at this time, the above parameters may be changed in proportion to the change in the emission intensity, or may be appropriately controlled in relation to the etching characteristics measured in advance.

Furthermore, similar effects can be obtained by detecting the plasma state by detecting the amount of ions of a specific mass obtained by mass spectrometry in addition to the plasma emission intensity.

In the embodiments described above, plasma etching using microwaves was given as an example, but parallel plate type plasma etching equipment and reactive ion etching equipment can also be used! Similar effects can be obtained using (RIB) and m-field RIg.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to continuously form plasma that corresponds to changes in the area to be processed of the object to be processed, so that it is possible to process patterns with high steps with good characteristics.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of a kneeling device according to an embodiment of the present invention, Fig. 2 is a schematic diagram of the relationship between time, emission intensity, and parameters in high-step pattern etching, and Fig. 3 is a diagram of the apparatus shown in Fig. 1. High step pattern etching characteristic diagrams, Figures 4 and 5
The figure is an etching characteristic diagram for a flat pattern and a high-step pattern according to the prior art. 1, l'... Photoresist, 2.2'...
・・Etched material (M-based wiring material), 3, 3'...
Base layer, 14... Etching gas, 13...
...Controller, J...Receiver, 10...
...RF'! ! , 4...μ wave input flash

Claims (16)

[Claims] 1. A plasma processing method characterized by continuously detecting the state of plasma and continuously controlling plasma parameters according to changes in the detected amount. 2. The plasma processing method according to claim 1, wherein the plasma parameters are continuously controlled after a predetermined period of time has elapsed after the start of plasma processing. 3. The plasma processing method according to claim 1, wherein light emission of plasma is detected as the state of the plasma. 4. The plasma processing method according to claim 1, wherein the parameter is controlled in proportion to a change in the detected amount. 5. The first plasma treatment is plasma etching.
A plasma processing method according to the claims. 6. 6. The plasma processing method according to claim 5, wherein the plasma parameter is an etching gas flow rate. 7. 6. The plasma processing method according to claim 5, wherein the plasma parameter is pressure. 8. The plasma processing method according to claim 5, wherein the plasma is generated using a microwave electric field. 9. 9. The plasma processing method according to claim 8, wherein a high frequency voltage is applied to a susceptor on which the object to be processed is placed, and the high frequency voltage is used as the plasma parameter. 10. 7. The plasma processing method according to claim 6, wherein the material to be etched is an Al-based wiring material. 11. 10. The plasma processing method according to claim 10, wherein the etching gas flow rate is controlled in relation to an etching rate ratio (selectivity) between a photoresist as a mask material and the wiring material. 12. 6. The plasma processing method according to claim 5, wherein the parameters are controlled in relation to selectivity with respect to the base material, etching shape, or residue. 13. In a method for etching etching materials that are provided in high step areas and have greatly different thicknesses, the state of the plasma is continuously detected, and the plasma parameters are continuously adjusted from the point of over-etching in response to changes in the detected amount of the plasma state. A plasma processing method characterized by controlled control. 14. 14. The plasma processing method according to claim 13, wherein the over-etching is controlled by time setting. 15. 6. The plasma processing method according to claim 5, wherein the plasma processing is reactive ion etching. 16. Al that is installed in a high step part and has a large difference in thickness
An etching treatment method for etching a wiring material, characterized in that the etching gas flow rate is changed during over-etching to improve selectivity with respect to photoresist.