JP3170849B2 - Dry etching method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a dry etching method in a semiconductor manufacturing method.

[0002]

2. Description of the Related Art In recent years, demands for an etching shape and a dimensional shift in a dry etching technique have become strict with the miniaturization of a pattern of a semiconductor device. Therefore, controlling the wafer temperature that affects the shape and dimensional shift is one of the important technologies in dry etching.
Has become one. One method of controlling the wafer temperature is electrostatic attraction.

[0003] The electrostatic attraction will be described below. FIG. 1 is a schematic diagram showing an example of a reactive ion etching apparatus. Reactive gas is introduced into the metal chamber 1 through a gas controller 5, and is controlled to an appropriate pressure by an exhaust system 2. An anode (anode) 3 is provided at the upper part of the chamber 1 and a cathode (cathode) 4 is provided at the lower part.
Is provided, and the wafer 8 is disposed on the cathode 4. An RF power source 7 is connected to the cathode 4 via an impedance matching circuit 6.
And a high-frequency discharge can occur between them. Positive ions in the plasma generated by the discharge are attracted to the cathode when the high-frequency power is negative, and electrons are attracted to the cathode when the high-frequency power is positive. However, since electrons have a smaller mass than ions, more electrons are attracted to the cathode and the wafer is negatively charged. When the surface of the cathode is made of a dielectric material, the charged electrons are difficult to escape,
Since it has the same shape as a capacitor, an attractive force acts on the wafer and the cathode due to static electricity. In this way, by adsorbing the wafer and the cathode by electrostatic force, heat exchange between the wafer and the cathode can be promoted and the temperature of the wafer can be controlled.

[0004]

However, when the above-mentioned electrostatic attraction is used, the charge on the wafer remains even after the etching is completed, so that the wafer is strongly attracted to the electrodes and the etched wafer is transferred. In this case, there is a problem that a transport error may occur.

The present invention solves the above-mentioned conventional problems, and provides a dry etching method that eliminates a transfer error due to electrostatic attraction by removing charge on a wafer after etching or by generating a plasma that weakens the charge. The purpose is to provide.

[0006]

In order to achieve this object, the present invention provides a method of disposing a substrate on one electrode in a reaction chamber,
Introduce the reaction gas into the reaction chamber and create a high circumference between both electrodes
Generates plasma by applying wave power and reacts
Dry etching method for etching indoor substrates
And generate plasma of the reaction gas to etch the substrate.
Separate from the process of at least inactive in the same reaction chamber
Gas and nitrogen-containing gas
Apply high-frequency power, which is lower than the power of the process, between both electrodes.
Process to generate plasma and remove electrification of the substrate.
You.

In the step of removing the charge, the influence on the semiconductor device can be reduced by reducing the applied high frequency power, but at least one of the gases to be introduced is introduced in the step of etching the semiconductor wafer. By using the same gas, the effect on the semiconductor device in the step of removing the charge can be further reduced.

[0008] Further, by using at least one kind of gas introduced in the step of removing the charge of oxygen, the reaction chamber can be cleaned while removing the charge.

[0009]

According to the present invention, in the first step, dry etching with good temperature control is performed by using electrostatic attraction ,
In the eye step, the charge on the wafer can be removed or the charge amount can be reduced and the electrostatic attraction force can be weakened. It is possible. Here, the second step will be described in detail. In the second step, since the power is small, the Coulomb force at which electrons and ions are attracted to the cathode during discharge also becomes small. As a result, the velocities of both electrons and ions are reduced, but the difference in velocities is also reduced, so that the negative charge amount in the steady state is also reduced. Therefore, the charge amount can be reduced and the electrostatic attraction force can be reduced by the second step.

[0010]

An embodiment of the present invention will be described below with reference to the drawings.

The dry etching method of the present invention can also be carried out using the above-described dry etching apparatus shown in FIG. Reactive gas is introduced into the metal chamber 1 through a gas controller 5, and is controlled to an appropriate pressure by an exhaust system 2. An anode (anode) 3 is provided at an upper portion of the chamber 1, and a cathode (cathode) 4 is provided at a lower portion, and the wafer 8 is disposed on the cathode 4. An RF power source 7 is connected to the cathode 4 via an impedance matching circuit 6, and high-frequency discharge can be generated between the cathode 4 and the anode 3. After the completion of the etching, the push-up mechanism 9 rises to lift the wafer. The lifted wafer is transferred to the load lock chamber by the transfer mechanism. The material of the cathode 4 is aluminum, and the surface is anodized.

[0012] CF ₄ and O ₂
When a gas was introduced, a high-frequency power of 300 W was applied to generate plasma, and the SiO ₂ film was etched. After the etching, the wafer was attracted to the cathode by electrostatic force. Therefore, if the wafer 8 is lifted by the push-up mechanism 9 in this state, the wafer 8 jumps and shifts its position. Therefore, after etching, the discharge is once stopped, CF ₄ gas is introduced, and a high frequency of 1/6 of the power for etching is applied for 10 seconds. As a result, the wafer did not jump due to the push-up. Table 1 shows the results of the wafer jumping up due to the thrust, including the results obtained when a gas other than CF ₄ was introduced in the step of removing the charge.

[0013]

[Table 1]

It can be seen from the table that gases other than CF ₄ also have the effect of eliminating wafer charging. Table 1 also shows the etching rate of the underlying Si in the step of removing the charge. From the table, it can be seen that in the case of a discharge containing a reactive gas, an inert gas, or nitrogen used in the step of etching a semiconductor, the etching rate of Si is 0. Therefore, the influence on the semiconductor device can be reduced by using the above gas as the gas used in the step of removing the charge.

When O ₂ was used in the step of removing the charge, there was a cleaning effect. FIG. 2 shows the variation of the etching rate of the SiO ₂ film in the etching step. Curve 11 is CF ₄ discharge, curve 12 is O ₂ discharge, and curve 13 is N ₂
The result of the discharge is shown. The rate is most stable when O ₂ is used in the step of removing charging from the figure. This is because the atmosphere in the reaction chamber is constant due to the cleaning effect by O ₂ plasma.

Table 2 shows the results of the electrostatic adsorption when the high frequency power was changed by introducing CF ₄ gas in the step of removing the charge.

[0017]

[Table 2]

From this table, it can be seen that the high frequency power applied in the step of removing the charge is 1/1 / of the step of etching the semiconductor wafer.
It can be seen that an effect is obtained when the value is 3 or less.

Table 3 shows the results of the electrostatic attraction when the discharge time was changed when CF ₄ gas was introduced in the step of removing the charge.

[0020]

[Table 3]

From this table, it can be seen that it is effective to apply a high-frequency power to generate plasma in the process of removing the charge by one minute or less.

In the above embodiment, the discharge is stopped between the step of etching the semiconductor wafer and the step of removing the charge. However, the same result can be obtained even if the discharge is performed continuously.

It is needless to say that the same result can be obtained by performing a discharge under other conditions between the step of etching the semiconductor and the step of removing the charge in order to stabilize the discharge in the step of removing the charge.

[0024]

As described above, according to the present invention, one side of the reaction chamber is provided.
Place the substrate on the electrode and introduce the reaction gas into the reaction chamber.
And applying high frequency power between both electrodes
Generates plasma and etches the substrate in the reaction chamber
In the dry etching method, the plasma of the reactive gas is
Apart from the process of generating and etching the substrate, the same
Gas containing at least inert gas or nitrogen in the reaction chamber
And high power with lower power than the previous process
Wave power is applied between both electrodes to generate plasma and
Controlling the temperature of the wafer by providing a process to remove electrification
It is possible to realize etching with good transportability and no transport error.

[Brief description of the drawings]

FIG. 1 is a schematic view showing the structure of a dry etching apparatus embodying the present invention.

FIG. 2 is a diagram showing a change in an etching rate of a SiO ₂ film;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal chamber 2 Exhaust system 3 Anode 4 Cathode 5 Gas controller 6 Impedance matching circuit 7 High frequency power supply 8 Semiconductor wafer 9 Push-up mechanism

Continued on the front page (72) Inventor Yoshinobu Nagano 1006 Kadoma, Kazuma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. References JP-A-3-240947 (JP, A) JP-A-5-114585 (JP, A) JP-A-3-243188 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB Name) H01L 21/3065 C23C 16/56 C23F 4/00

Claims (6)

(57) [Claims] 1. A plasma is generated by disposing a substrate on one electrode in a reaction chamber, introducing a reaction gas into the reaction chamber, and applying high-frequency power between the two electrodes.
In a dry etching method for etching a substrate in a reaction chamber, separately from a step of generating a plasma of a reaction gas and etching the substrate , at least
Before introducing inert gas or gas containing nitrogen
High-frequency power, which is lower than the above process, is applied between both electrodes.
Process to generate plasma by removing the charge on the substrate
A dry etching method. 2. The method according to claim 1, wherein the substrate is a semiconductor wafer.
The method of dry etching. 3. The method according to claim 1, wherein a small amount of gas introduced in the step of removing the charge
At least one type is a process for etching a semiconductor wafer
The dry etching method according to claim 1 or 2, wherein the same gas is used as the gas introduced in (1) . 4. The method according to claim 1 , wherein oxygen is introduced into the gas introduced in the step of removing charge.
The dry etching method according to claim 1, wherein the dry etching method is included . 5. A high-frequency power applied in a step of removing charging.
Is less than 1/3 of the power in the process of etching semiconductor wafers
The dry etching method according to claim 1 or 2, wherein: 6. A high-frequency power is applied in a step of removing charging.
The time for generating additional plasma is 1 minute or less.
3. The dry etching method according to 1 or 2 .