JPH05279876A - Dry etching method - Google Patents

Abstract

PURPOSE:To prevent the trouble in the conveyance of a substrate caused by electrostatic attraction by generating plasma with low power density and removing charging on the substrate. CONSTITUTION:Reaction gases of CF4, SF6 and O2, are introduced into a chamber 1 through an etching gas flow rate controller By a high-frequency power source 5, high-frequency power with 1.0w/cm<2> power density is impressed on the space between the anode 2 and cathode 3 to generate plasma, and the etching of a silicon nitride film is executed on a glass substrate 10. After that, the discharge is once cut off, a CF4 gas is introduced therein, high-frequency power with about 0.6w/cm<2> power density is impressed thereon for 30sec, and a substrate thrusting pin 8 is raised by an up-down driving source 9. By this method, since the negative charging amt. of the substrate 10 is reduced, it smoothly separated from the cathode 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display manufacturing method, and more particularly to dry etching.

[0002]

2. Description of the Related Art In recent years, in dry etching technology used for thin film processing in a liquid crystal display manufacturing process, requirements for etching shape and pattern accuracy have become strict. In dry etching, since the etching shape and the pattern accuracy largely depend on the substrate temperature, the substrate temperature control technique is regarded as important. Electrostatic attraction is used to control the substrate temperature. Electrostatic attraction
This is a method in which a voltage is applied between an electrode and an adsorbate across an insulator and a Coulomb force is developed between the two to attract the adsorbate. As a result, the substrate is attracted by the electrostatic force as compared with the conventional mechanical chucking method, so that the adhesion between the substrate and the electrode can be controlled, and the substrate temperature control is excellent.

Next, electrostatic attraction in dry etching will be described. FIG. 1 shows an example of a reactive ion etching apparatus. A chamber 1 for etching is mainly made of metal, an anode 2 is arranged on an upper portion thereof and a cathode 3 is arranged on a lower portion thereof, and a glass substrate 10 is placed on the cathode 3. An RF high frequency power source 5 is connected to the cathode 3 through an impedance matching circuit 4. Further, the inside of the chamber 1 is supplied with a reactive gas through the etching gas flow rate controller 6, and is kept at a constant pressure by a pressure controller 7 provided in the vacuum exhaust system passage 12. Anode 2 by high frequency power supply 5
High frequency discharge can be generated between the cathode and the cathode 3,
When the high frequency power is negative, positive ions in the plasma generated by the discharge are attracted to the cathode 3, and when the high frequency power is positive, the electrons are attracted to the anode 2. However, since the mass of electrons is smaller than that of ions, the number of electrons attracted to the cathode 3 increases and the glass substrate 10 is negatively charged. If the surface of the cathode 3 is made of a dielectric, it becomes difficult for charged electrons to be released,
In addition, since the shape is similar to that of a capacitor, an attractive force due to static electricity acts between the substrate 10 and the cathode 3. This state is shown in FIG. In this way, by adsorbing the substrate 10 and the cathode 3 by electrostatic attraction, heat exchange between them can be promoted and the substrate temperature can be controlled. The substrate push-up pin 8 is moved up and down by the lifting drive source 9.

[0004]

However, when the above electrostatic attraction is used, the electrostatic charge on the glass substrate 10 remains after the etching, and therefore the residual electrostatic attraction between the substrate 10 and the cathode 3 causes the substrate to be charged. 10 adheres to the cathode 3, and there is a problem in that when the substrate is transported after etching, the glass substrate 10 is cracked when the substrate push-up pin 8 is lifted by the lifting drive source 9 and other transport problems occur. Note that FIG. 3 shows a state in which the glass substrate 10 is normally pushed up by the push-up pin 8.

The present invention solves the above-mentioned problems, and by removing or weakening the charge on the substrate by plasma after etching the thin film on the substrate, dry etching which does not cause substrate transfer trouble due to electrostatic attraction. The purpose is to provide a method.

[0006]

In order to achieve the above object, the dry etching method of the present invention is performed in the same chamber as the process of etching a thin film on a glass substrate with plasma by an etching gas, rather than in the etching step. A step of applying high-frequency power having a low power density to generate plasma to remove the charge on the glass substrate is provided.
Further, in the static elimination step of applying the high frequency power, the impact on the element on the surface of the glass substrate can be reduced due to the reduction of the power density.

[0007]

In the present invention, first, dry etching with good substrate temperature controllability using electrostatic adsorption is performed, and the electrostatic adsorption force can be weakened by removing or weakening the charge on the glass substrate in the next step. Therefore, the etching shape can be controlled by the substrate temperature, and the dry etching can be performed without any trouble in transportation. Now, the next step will be described. In the next step, since the power density is low, the Coulomb force of attracting electrons and ions to the cathode during discharge is also small. As a result, the speeds of electrons and ions decrease, but the speed difference between the two also decreases, so that the amount of negative charge on the substrate in the steady state also decreases. Therefore, the electrostatic charge can be weakened by reducing the charge amount of the glass substrate in the next step.

[0008]

EXAMPLES Examples of the present invention will be described below.

As the dry etching apparatus embodying the present invention, the same one as shown in FIG. 1 was used. Further, in this example, the glass substrate size is 150 mm × 200 mm, the electrode size is 1
80 mm × 230 mm was used.

In the above dry etching apparatus, CF ₄ , S
Introducing F ₆ and O ₂ gas, power density 1.0 W / cm ²
When the silicon nitride film on the glass substrate was etched by applying high-frequency power to generate plasma, when the glass substrate was electrostatically attracted to the cathode by electrostatic force after the etching was completed and the substrate push-up pin was raised. The board has cracked. Next, after the thin film on the substrate was etched under the same conditions, the discharge was once cut off, CF ₄ gas was introduced, and high frequency power with a power density of about 0.6 W / cm ² was applied for 30 seconds. There are no cracks left. The results when CF ₄ , SF ₆ and O ₂ gas were introduced in the process of removing the substrate charge are shown in (Table 1).

[0011]

[Table 1]

Next, in the step of removing the charge on the substrate, CF ₄ , S
The state of electrostatic adsorption of the substrate when changing the high frequency power density using F ₆ and O ₂ gas is shown in (Table 2).

[0013]

[Table 2]

It can be seen from Table 2 that the high frequency power density applied in the static elimination step is effective when the power density is 0.6 W / cm ² or less.

Further, in the process of removing the charge of the substrate, CF ₄ ,
Table 3 shows the results of electrostatic adsorption of the substrate when the discharge time was changed by applying high-frequency power when SF ₆ and O ₂ gas were used.

[0016]

[Table 3]

From Table 3, it can be seen that the static elimination effect appears by applying high frequency power in the static elimination step and setting the discharge time to 1 minute or less.

Further, the above effects can be obtained not only by using CF ₄ , SF ₆ , and O ₂ gas alone but also by using a mixed gas containing them. In addition, in this implementation, the glass substrate size was 150 mm x 200 mm and the electrode size was 180 mm x 230 mm, but even if the glass substrate size and the electrode size change,
It goes without saying that the same effect can be obtained.

In order to stabilize the discharge state in the step of removing the charge on the glass substrate, discharge is performed under other conditions between the step of etching the thin film on the glass substrate and the step of removing the charge on the substrate. It is clear that similar results can be obtained even if it is performed.

Further, in the above embodiment, the discharge is cut off between the step of etching the thin film on the glass substrate and the static elimination step, but similar results can be obtained by continuous discharge.

[0021]

As described above, according to the present invention,
A glass substrate is placed on one side of a parallel plate electrode installed in a chamber whose pressure is controlled by introducing an etching gas, and high-frequency power is applied between both electrodes to generate plasma. In the process of dry-etching the thin film of, the process of generating plasma of the reaction gas to etch the thin film on the glass substrate and the high-frequency power having a lower power density than the previous process in the same chamber are applied to generate plasma. By providing the static elimination step for generating and weakening the adsorption to the electrode due to the charging of the glass substrate, the conventional substrate temperature controllability can be maintained, and in addition, dry etching with high reliability of substrate transportation can be realized.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a structure of a dry etching apparatus embodying the present invention.

FIG. 2 is a configuration diagram showing a state where a substrate is adsorbed on an electrode after etching.

FIG. 3 is a configuration diagram when the board is normally pushed up in FIG.

[Explanation of symbols]

 1 Metal Chamber 2 Anode 3 Cathode 4 Impedance Matching Circuit 5 High Frequency Power Supply 6 Gas Controller 7 Pressure Controller 8 Substrate Push-up Pin 9 Substrate Push-up Pin Elevating Drive Source 10 Glass Substrate 11 Vacuum Exhaust System Path

Claims (3)

[Claims] 1. A plasma is generated by placing a substrate on one electrode in a reaction chamber provided with parallel plate electrodes, introducing an etching gas into the reaction chamber, and applying high-frequency power between the electrodes, A dry etching method comprising: in dry etching for etching a thin film on a glass substrate in a reaction chamber, applying a high-frequency power lower than that during etching after the completion of etching to generate plasma. 2. The applied power density after etching is 0.
The dry etching method according to claim 1, wherein the dry etching rate is 6 W / cm ² or less. 3. The time for applying high-frequency power and generating plasma after etching is set to 1 minute or less.
The dry etching method described.