JPH03236230A - Plasma etching method - Google Patents

Abstract

PURPOSE:To perform plasma etching for wiring material with stabilized etching performance at high machining accuracy by forming plasma from a gas wherein shape-controlling preventive gas is added into chlorine-based gas, utilizing the gas plasma, and etching the wiring material. CONSTITUTION:In order to treat a sample 10 by plasma etching, a gas wherein shape-controlling preventive gas is added into chlorine-based gas is used as a treating gas. The mixed gas in a plasma forming region is made to be plasma by the synergistic effect with a microwave electric field. This plasma is utilized, and the sample is 10 is etched. At this time, an RF bias is applied to the sample 10. The side wall formed by the etching is protected with a polymer 30 formed from photoresist 14 and an etching reaction product 31. When the etching is finished, a high anisotropic shape is obtained. With respect to an Si oxide film 11 which is a ground oxide film, the Si oxide film 11 is hard to be etched, and high selectivity is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a plasma etching method, and particularly to a plasma etching method suitable for plasma etching wiring materials in a semiconductor substrate.

[Conventional technology]

In conventional etching, since etching is performed using a fluorine-based gas, side etching tends to occur, and in order to prevent this, it is necessary to add a deposit-prone gas.

In this case, the selectivity with respect to the underlying oxide layer was low, and the etching process deteriorated due to contamination in the processing chamber by the deposition gas.

Incidentally, as a method of this kind, for example, Japanese Patent Application Laid-open No.
No. 4419 is mentioned.

[Issues that Shinmei tries to solve]

The above conventional technology has shape controllability using debossing gas,
Furthermore, no consideration was given to the problem of contamination within the processing chamber, and there were problems with the highly accurate etching method for wiring materials.

SUMMARY OF THE INVENTION An object of the present invention is to provide a plasma etching method capable of plasma etching wiring materials with good processing accuracy and stable etching performance.

[Means to solve the problem]

In order to achieve the above object, the wiring material is etched using plasma of a chlorine-based gas to which a shape control gas is added.

[For production]

When etching wiring materials using plasma of chlorine-based gas with shape control gas added, the etching rate is higher than when etching wiring materials using conventional fluorine-based gas plasma. This makes it possible to perform etching processing with a high etching selectivity and with less contamination of the processing chamber due to deposited silane.

〔Example〕

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

FIG. 1 is a partial vertical cross-sectional view of the sample in this example. In FIG. 1, sample 10 has a Po1x-Si film cross on the S1 oxide film U, which is the underlying oxide layer, and WSix!
l! There are 13 exhibitions for gate wiring. Also, W.S.
On the iX film U, a photoresist 14 is provided corresponding to a predetermined wiring pattern.

In order to plasma-etch the sample IO shown in FIG. 1, the processing gas used in this case is C12 gas and Si
A mixed gas of 4 gases was used. Furthermore, a known magnetic field type microwave plasma etching apparatus was used as the etching apparatus.

In this case, in the plasma generation area of the etching device, C1
Add 30% SiC/4 gas to 2 gases, total flow rate 7
Mixing was introduced at 0 cc/min. The pressure in the plasma generation region into which the mixed gas was introduced was adjusted and maintained at 0.01 Torr. In this pressure state, the mixed gas in the plasma generation region was turned into plasma by a synergistic effect with the microwave electric field. In this case, the microwave power is 2.4
It is 500W at 5 GHz. Sample 10 was etched using the plasma. At this time, an RF bias of 120 W was applied to sample 10. In this case, ′Wi
As shown in the z diagram, wcz, 20 or SiC/x2
WSjx film 13, P by reaction of 1 and C/radical 22
o1y -81 [% L! Etching progresses along the photoresist 14. The side walls formed by the etching were protected by the polymer film produced from the photoresist 14 and the etching reaction product 5, and at the end of the etching, a highly anisotropic shape as shown in FIG. 3 was obtained. Furthermore, for the 5i oxide M11, which is the base oxide film, since a fluorine-based gas (hereinafter abbreviated as F-based gas) as in the conventional case is not used, the Si oxide film 11 is hardly etched and high selectivity can be obtained.

A plurality of samples 10 were successively etched under the above etching conditions. FIG. 4 shows the results obtained, and is a diagram showing the relationship between the number of etched samples (hereinafter referred to as the number of processed samples) and the etching rate of Po1y-Si. FIG. 4 also shows the results when F-based gas was used.

In the 1M4 diagram, in this example, P when the number of sheets to be processed is 1
G/)/-f3i knee rate is about 340 nm/
Po/y at a processing number of 200 sheets compared to
The -8+ etch rate was about 325 nm/min. On the other hand, when F-based gas is used, the P
The zy thyrate of o1y-Si is approximately 325 nm/m i
Poppy with a processing number of 200 sheets compared to n.
-Si etch rate was about 260 nm/min. In this way, in this example, the sample 10 is
Even if 00 sheets are etched continuously, the Po
The decrease in the etching rate of 1y-Si is smaller than that when F-based gas is used. In other words, stable etching performance can be obtained.

This is because the contamination inside the etching processing chamber of the etching apparatus is less in this embodiment than in the case where F-based gas is used. In addition, when F-based gas is used, Poppy −
The butyrate of Si shows a tendency to decrease after the number of processed sheets is 100, and contamination in the etching processing chamber rapidly progresses.

According to this embodiment, WSix/POl'j Si
The second layer group for gate wiring can be etched with high processing accuracy, and the etching process can be performed with stable etching performance with little contamination in the etching process chamber.

Note that Si 2 C/ in the above embodiment is a shape control gas. As the shape control gas, a gas to which a chlorine-based gas or a carbon-containing gas is added may be used. By turning a mixed gas of such a shape control gas and a chlorine-based gas into plasma and etching the gate film on the Si substrate using the plasma, the etching process can be performed with good processing accuracy and stable etching performance.

Furthermore, Si C14, CC14 is added to C12 or HCJ.
゜CHCJ3. CH2F2. A gas doped with a gas selected from CHF5 can be used as a mixed gas, whereas as a gate group on a Si substrate, PG/y
-5i single shoe exhibition, No SIx / Pony -Si
A gate wiring layer of a film or a W film is used.

In addition, in this embodiment, the mixed gas is turned into plasma by the synergistic effect of the microwave electric field and the magnetic field, and the wiring material on the biased substrate is etched using the plasma. Alternatively, the mixed gas may be turned into plasma by a microwave electric field, that is, microwave discharge, and the wiring material on the biased substrate may be etched using the plasma.

〔Effect of the invention〕

According to the present invention, there is an effect that wiring material can be plasma etched with good processing accuracy and stable etching performance.

[Brief explanation of drawings]

FIG. 1 is a partial vertical cross-sectional view of a sample in an embodiment of the present invention;
Figure 2 is a partial vertical cross-sectional view showing the concept of the etching progress of the sample in Figure 1, Figure j@3 is a partial vertical cross-sectional view of the sample in Figure 1!1 at the end of etching, and Figure i@4 is FIG. 2 is an experimental relationship diagram between the number of processed samples of FIG. 1 and Poly-Si etching rate. 10...Sample, U...Si oxidation, C...Po1y-11Figure 2AJ Flash

Claims (1)

[Claims] 1. The method is characterized by comprising the steps of: 1. converting a gas in which a shape control gas is added to a chlorine-based gas into plasma; and etching a wiring material using the gas plasma. Plasma etching method. 2. The plasma etching method according to claim 1, wherein the gate wiring film on the silicon substrate is etched using plasma of a gas to which a chlorine-based gas or a carbon-containing gas is added as the shape controlling gas. 3. SiCl_4, CCl_ to Cl_2 or HCl
4. Poly-Si single layer film, WSix/Pol on silicon substrate using gas plasma added with gas selected from CHCI_3, CH_2F_2, CHF_3
2. The plasma etching method according to claim 2, wherein a gate wiring film selected from a y-Si film, a MoSix/Poly-Si film, and a W film is etched. 4. A step of converting a gas in which a shape control gas is added to a chlorine-based gas into plasma by microwave discharge, and a step of etching the wiring material on the biased substrate using the gas plasma. A plasma etching method characterized by: