JPS5852325B2 - Plasma etching processing method and processing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a processing method and a processing apparatus for performing stable plasma etching processing.

FIG. 1 shows a schematic diagram of a general plasma etching apparatus.

In this device, a workpiece 1 is placed on a first electrode 2, and a
The object to be processed 1 is etched by generating plasma 5 using high frequency waves 4 between the electrode 2 of M2 and the electrode 3 of M2.

Now, let us consider the case where the photomask shown in FIG. 2 is etched using the plasma etching apparatus shown in FIG.

The photomask shown in FIG. 2 is, for example, formed by forming a metal film (for example, Cr) 10 with a thickness of about 500 mm on a glass substrate 9, and then coating a resist 11 with a predetermined pattern on it with a thickness of about 500 mm.
Has an A-grade appearance.

Then, the metal film 10 is etched using a plasma etching device using the resist 11 as a mask O, thereby forming a photomask in which a predetermined pattern of the metal film 10 is provided on the glass substrate 9.

In the actual etching process using a plasma etching apparatus as shown in FIG. 1 of the above-mentioned Fort Mask,
First, a photomask in the state shown in FIG. 2 is placed on the first electrode 2 as the object to be processed 1, and after the inside of the apparatus is evacuated using, for example, a vacuum pump 6, carbon tetrachloride (CC14) gas, for example, is supplied through the supply hole 7. Supply the gas pressure inside the device to 8X 10-3T
Create an atmosphere of orr.

Plasma 5 is then generated by high frequency waves 4 from an oscillator.

At this time, since plasma is difficult to generate at first, it is necessary to apply high voltage and high frequency between the first and second electrodes in the initial stage of plasma generation.

Furthermore, the same high frequency is applied to the auxiliary electrode 8 provided very close to the second electrode 3 to generate plasma between the second electrode 3 and the auxiliary electrode 8, and to generate a plasma between the first and second electrodes. This makes it easier for plasma to be generated.

Specifically, for example, the distance between the first and second electrodes is approximately 8 cm.
rIL1 When the distance between the second electrode 3 and the auxiliary electrode 8 is about 3, the high plate voltage at the initial stage is about 4.6KV1
At that time, a plate current of approximately 1.02A is required.

Since the distance between the second electrode 3 and the auxiliary electrode 8 is close, about 3 times, plasma is generated easily, and then plasma is generated between the first and second electrodes.

Once the plasma has stabilized, the plate voltage is increased to approximately 2.2 K and the V1 plate current is approximately 1.75 A (
Strain and perform plasma etching.

The problem is that when plasma is first generated (due to the high plate voltage, the atmosphere between the two electrodes becomes unstable plasma state, and the resist 11 of the photomask, metal film 10, etc., which is the object 1 to be processed, etc.) An unstable plasma state (due to this, an overcurrent occurs), damage such as melting or peeling occurs, and normal plasma etching may not be performed.

The present invention eliminates the above-mentioned conventional drawbacks and provides a processing method and processing apparatus that prevents unstable plasma in the initial stage of plasma generation from adversely affecting the object to be processed and performs normal plasma etching. The purpose is to

According to the present invention, the above object is achieved by plasma etching in which plasma is generated between a first electrode on which an object to be processed is placed and a second electrode opposing the first electrode. In the treatment method, a third electrode is provided separately from the first and second electrodes, and the third electrode is positioned between the first electrode and the second electrode. generating an initial plasma by applying a high frequency between the third and second electrodes, and not placing the object to be processed in the initial plasma; 3. Stopping the application of high frequency between the second electrodes and applying high frequency between the first and second electrodes to generate plasma therebetween to etch the object to be processed. A plasma etching processing method characterized by: and a plasma etching processing apparatus that performs etching by generating plasma between a first electrode on which an object to be processed is placed and a second electrode opposing the first electrode. A third electrode is provided between the first and second electrodes and generates plasma between the second electrode, and plasma generation between the third and second electrodes; This is achieved by providing a plasma etching processing apparatus characterized in that it is provided with a switch means for switching plasma generation between the first and second electrodes.

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

FIG. 3 shows a schematic diagram of a plasma etching processing apparatus according to an embodiment of the present invention.

This device differs from the conventional device shown in FIG.
is provided, and a switch 13 outputs a high frequency signal 4 from the oscillator.
can be guided to either the first electrode 2 or the third electrode 12.

The plasma etching method of this embodiment is carried out in the following manner using a processing apparatus having the structure described above.

First, in the initial stage of plasma generation, the third electrode 12 is interposed between the eleventh and second electrodes, the high frequency wave 4 is guided to the third electrode 12 by the switch 13, and the third electrode 12 and the second
An initial plasma is generated between the electrodes 3 of.

Then, when the plasma becomes stable, the third electrode 1
For example, the high frequency wave 4 from the oscillator is guided to the first electrode 2t/2t by retracting the high frequency wave 4 from the oscillator from between the first and second electrodes and switching the switch 13.

By performing plasma etching in this manner, the object to be processed 1 is not placed in an unstable initial plasma, so that damage to the object to be processed 1 as described above can be prevented.

Next, a specific example will be described in which plasma etching is performed using the photomask shown in FIG. 2 as the object to be processed 1.

First, in the processing apparatus shown in FIG. 3, for example, the distance between the first and second electrodes is approximately 8 cIf, and the distance between the third and second electrodes is approximately 6 cIf.
The distance between L1 second electrode 3 and auxiliary electrode 8 is approximately 3m1JL
It is.

Also, the inside of the processing equipment was filled with carbon tetrachloride (CC14) to a gas pressure of about 8×10-” Torr.

In the initial stage, the third electrode 12 is inserted between the first and second electrodes, and the plate voltage is set to 1.7 KV and the plate current is set to 1.5 Al.

At this time, a similar high frequency wave 4 is also guided to the auxiliary electrode 8.

First, plasma is generated between the auxiliary electrode 8 and the second electrode 3, and furthermore, plasma is generated between the third electrode 12 and the second electrode 3.

At this time, the object 1 to be processed is not in the initial unstable plasma.

After this plasma stabilizes (in this example, about 10
seconds later), the third electrode 12 is rotated, for example, around the shaft portion 12', moved away from between the first and second electrodes, the switch 13 is switched, and the plate voltage is further increased to 2.2 KV1.
Change the plate current to approximately 1.75A.

Then, by supplying stable plasma for about one minute, the metal film 10 of the photomask, which is the object to be processed 1, is normally plasma etched.

Note that the plate voltage at the initial stage of plasma generation is determined by the fact that the distance between the third electrode 12 and the second electrode 3 is shorter than that between the conventional first electrode 1 and the second electrode 3. This means that plasma can be generated at a lower voltage (approximately 1.7 KV) than in the past.

Next, as another example, a case where the third electrode is made of a mesh-like metal will be described.

The third electrode in the above-mentioned embodiment was one that rotated around the shaft 12', for example, but by using a mesh-like metal for the third electrode as in this embodiment, the third electrode rotates around the shaft 12'. The plasma etching process described above can be performed with the electrode fixed.

The mesh-shaped metal is made of copper, for example, and has a diameter of 0.5 mr.
rt wire into a mesh shape with a pitch of approximately 1.0 cm.

When this mesh-like metal is used as the third electrode,
The distance between each electrode of the processing device and various conditions during processing may be substantially the same as those of the above-mentioned embodiment.

The difference is that the third electrode is fixed between the first and second electrodes, and after the plasma has stabilized, the third electrode is fixed between the first and second electrodes.
The point is that it is only necessary to switch only the switch 13 from the third electrode to the first electrode without retreating from between the electrodes.

This embodiment has the advantage that the processing device is simplified.

As explained above, according to the present invention, the part to be processed is not placed in unstable plasma when plasma is first generated in plasma etching, but the part to be processed is plasma-etched when the plasma becomes stable. Damage to the object to be processed due to stable plasma can be prevented, and normal and good plasma etching can be performed.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a conventional plasma etching processing apparatus. FIG. 2 is a cross-sectional view of a photoresist as an object to be processed. FIG. 3 is a schematic diagram of a plasma etching processing apparatus which is an embodiment of the present invention. In the figure, 1: object to be processed, 2: first electrode, 3: second electrode, 4: high frequency, 5: plasma, 12: third electrode.

Claims (1)

[Scope of Claims] 1. A plasma etching method in which etching is performed by generating plasma between a first electrode on which an object to be processed is placed and a second electrode opposing the first electrode. 1. Separate from the second electrode (a third electrode is provided, and the third electrode is positioned between the first electrode and the second electrode). , applying a high frequency between the second electrodes to generate an initial plasma, and not placing the object to be processed in the initial plasma;
After the plasma is stabilized, the application of the high frequency between the third and second electrodes is stopped, and the high frequency is applied between the first and second electrodes to generate plasma therebetween to etch the object to be processed. A plasma etching method comprising the steps of: 2. Between the first electrode on which the object to be processed is placed and the second electrode opposing the first electrode (in the plasma etching processing apparatus O that generates plasma to perform etching), A third electrode is provided between the second electrodes and generates plasma between the third electrode and the third electrode.
. A plasma etching processing apparatus, comprising a switch means for switching generation of plasma between the second electrode and generation of plasma between the first and second electrodes. 3. The plasma etching processing apparatus according to claim 2, wherein the third electrode is made of a mesh-like metal.