JPS60189224A - Dry etching apparatus - Google Patents

Abstract

PURPOSE:To provide a high-rate magnetron etching apparatus which generates uniformly high-density plasma over a material and has a uniform etching rate, by providing with a column cathode having end plates each with a larger cross- sectional area and a magnetic circuit which generates magnetic field in parallel with the axis of the column cathode. CONSTITUTION:When high frequency power is applied between the cathode 101, 103, 104 and the material electrode 100, and the reactive vessel 110 by RF electric sources 109, 190, plasma is caused to generate around the column electrode 101. Owing to the magnetic field B by coils 114, 115, electrons diffuse toward the ends of the column electrode 101 while rotating. The electrons are repelled by the ends plates 103, 104 and are returned toward the center of the column electrode 101. A region having a very high plasma density is formed near the column electrode 101. Since the plasma impedance decreases owing to mutual function of the plasma and a negative self-bias voltage on the surface of the material 102, a large ion-current can be caused to flow through the material electrode at a low voltage and therefore an etching rate of the material 102 can be highly improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dry etching apparatus used for forming patterns of semiconductor integrated circuits and the like.

In recent years, with the miniaturization of semiconductor integrated circuits, large-scale integrated circuits with minimum pattern dimensions of 1 μm or less have been prototyped, developed, and are beginning to be mass-produced. Conventional wet etching cannot process this fine pattern, so anisotropic etching using dry etching has become an indispensable technique for processing these integrated circuits. There are several types of dry etching equipment, but one uses parallel plate type electrodes and high-frequency plasma of a reactive gas containing oxides.

The reactive ion etching device that etches the sample is
Aluminum, silicon oxide, polysilicon, etc., while maintaining high etching rate selectivity between photohesist and underlying materials.

Since it is possible to perform anisotropic etching, the recent ultra-L
The clumsy isotching of the SI manufacturing process has become the mainstream.

However, it has become clear that various problems arise when attempting to carry out microfabrication on a mass production scale even with this reactive ion etching apparatus. For example, CHF a silicon oxide film
When etching with a mixed gas of 3 and 02, the etching speed is at most 500/^min, which is low.
In the case of etching a silicon oxide film having a size of 0.00, approximately 12 to 15 minutes of etching time is required, including additional etching. If the high frequency power is increased in an attempt to increase the etching rate, the plasma potential will rise and the proportion of sputtering on the reaction vessel wall will increase, resulting in the substrate surface being contaminated with heavy metals etc. that are the constituent materials of the reaction vessel. High-energy ion bombardment may adversely affect device characteristics. on the other hand.

Even in the case of aluminum etching and polysilicon etching, the etching speed is practically 100 O at most.
A/min, so when used as a mass production device, a so-called batch type device that processes about 6 to 10 sheets at the same time was superior in terms of cost performance. However, recently, as the diameter of Ueno-- has become larger, such as 125 m or 150 m, it is difficult to process it using batch processing equipment.

As a result, the electrode area must be increased, and the device must be increased in size. Moreover, the uniformity of the etching rate within the plane has also tended to deteriorate, making it extremely difficult to microfabricate large-diameter wafers using ordinary batch equipment.

On the other hand, it has been proposed that each wafer is sequentially processed, but when etching is performed at high speed using this apparatus, the etching characteristics are poor.

In particular, it has the drawback of causing significant damage to devices, and it is not always possible to obtain satisfactory characteristics in microfabrication.

In contrast, recently a magnetic field has been used as a device to realize high-speed etching with less damage.
A high-speed magnetron etching method has been devised that performs high-speed etching in a region with pressures as low as ~2 digits. (Example: Patent application 1973
6-151394) However, in this type of device, plasma tends to concentrate only in the area where the electric field and magnetic field are exactly perpendicular to each other.

It is necessary to drive the magnet and move it frequently to change the magnetic field in order to equalize the etching rate distribution within the wafer, which has the disadvantage that the magnet drive mechanism requires a large amount of cost.

The present invention provides a new type of high-speed magnetron etching apparatus that eliminates the drawbacks of the above-mentioned high-speed magnetron etching apparatus, and can efficiently process a large number of samples at high speed with less damage to the substrate. So, use the drawing below.

This will be explained in detail with regard to an embodiment.

FIG. 1 shows an embodiment of the invention. In the figure, 1 old is circular.

It is a columnar electrode with a rectangular or polygonal cross section, and a sample electrode 100 is placed on the columnar surface of the counter device, and a sample 102 is placed on top of the sample electrode 100. 103 and 104 are end plates connected to the columnar electrode 101 at the same potential.

The areas of the end plates 103 and 104 are larger than the cross section of the columnar electrode 101, and their edges protrude from the columnar electrode in multiple turns.

One end plate 104 and sample electrode 100 are attached to nine reaction vessels 110 via insulators 105 and 106.

Each is covered with a shielding material according to its structure and necessity, and unnecessary discharge is removed from the end plate 104. Care is taken to prevent this from occurring on the back surface of the sample electrode 100, etc. A cathode composed of this columnar electrode 101 and end plates 103 and 104 is connected to a high frequency power source 10.
9 is connected. On the other hand, the sample electrode 100 is connected to a high frequency power source 190. (The high frequency power source 190 connects the sample electrode 100 and the cathodes 101 and 103.

It may be connected between 104 and 104. ) The reaction vessel 110 is connected to a vacuum pump via an exhaust pipe 111 and an exhaust valve 112. Reactive gas is introduced into 9 reaction vessels through gas controller 113. 11
4 and 115 are coils for generating a magnetic field approximately parallel to the axis of the columnar electrode around the columnar electrode. Now, in order to operate the apparatus of the present invention as described above, first, one reaction vessel 110 is passed through the exhaust pipe 111, and 10- to 10-
After evacuating to a vacuum of around Torr, the gas controller 1
Through 13.

Introduce a halogenated active gas such as CF4 or B-hazardous gas and maintain the vacuum at a total of 10 to 10 Torr. In this state, RF power supply 1
09 and 190, the Akane frequency power is applied to the cathodes 101 and 1
03, 104 and sample electrode 100 and 2 reaction vessels 1]0
When the voltage is applied between the two, plasma is generated around the columnar electrode 101. Now, at this time, the potential gradient generated in the ion source between the columnar electrode 101 and the plasma is between the coil 114 and the ion source.
Since the electrons are perpendicular to the magnetic field line arrow B of the magnetic field generated by 15, the electrons cause magnetron motion and move around the columnar electrode 101 as shown at 117.
It spreads towards the edge of 1. There are end plates 103 and 104 at both ends of the columnar electrode 101.
Since the electrons are negatively biased at the same potential as the end plate 1
03° 104 and returned to the center of the columnar electrode 101 as shown at 118. Since this state is repeated, a region with extremely high plasma density is generated near the columnar electrode 101. On the other hand, a negative self-bias voltage is applied to the sample surface due to the high frequency voltage applied to the sample electrode. Therefore, interaction with high-density plasma generated near the columnar electrode lowers the impedance of the plasma, allowing a large amount of ion current to flow through the sample electrode at low voltage. Therefore, the etching speed of the sample 102 placed opposite the columnar surface of the columnar electrode 101 can be dramatically improved compared to the conventional etching method. Not only that, the incident energy of ions incident on the sample 102 is significantly lower than that in conventional dry etching equipment, etc., and the plasma is sufficiently concentrated around the sample electrode 1000, which prevents ion incidence and impurity contamination. Etching can be performed with less damage caused by.

When using this device to process multiple samples, sample 10
A plurality of sample electrodes 100 similar to those shown in FIG. 1 can be arranged around the columnar electrode 101. At that time, the power source 190 can be provided either in common or individually for these sample electrodes, as required.

When the part of the sample electrode 100 other than the part covered by the sample 102 is large, it is preferable to cover that part with a cover plate made of quartz, Teflon, etc., and still cool the inside of the columnar electrode 101 with water using a water cooling pipe. bring results.

L [The cross-sectional shape of the columnar electrode 101 may be etched in a number of polygonal cross-sectional shapes such as triangular, hexagonal, hexagonal, etc., depending on the number of sample electrodes to be installed. possible at the same time.

The dry etching apparatus of the present invention is as shown above, and by using the present invention, high-density plasma can be generated uniformly on the sample surface very easily, and high-speed etching with uniform etching speed can be achieved. This can be achieved without damaging the sample.

In the above-described embodiments of the present invention, an electromagnetic coil is used as the magnetic circuit, but it goes without saying that this may be replaced with a water-immersed magnet.

The industrial value of the present invention, which enables high-quality, high-speed sputter etching with a simple device, can be said to be an industrially useful invention.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the invention. 101...... Column electrode 102...
...... Sample 103.104... End plate 105.106... Insulator 109.190-... High frequency power supply 110...
・・・・・・Reaction container 111・・・・・・・・・・・・
Exhaust pipe 112...・Exhaust valve 113...
...... Gas controller 114.115
......Coil 117.118...Electronic patent applicant Nichiden Anelva Corporation

Claims (1)

[Claims] A cathode consisting of a columnar electrode and an end plate having a larger cross-sectional area than the columnar electrode and having the same potential connected to both ends thereof, and a reaction vessel wall surrounding the cathode. a sample electrode placed opposite the columnar surface of the columnar electrode; and means for applying a high frequency or DC voltage between the anode and the anode. The method comprises a means for applying a high frequency or DC voltage between the anode or the cathode and the sample electrode, and a magnetic circuit that generates a magnetic field parallel to the axis of the columnar electrode, and the sample placed on the sample electrode is A dry etching device characterized by etching using active gas plasma introduced into a reaction vessel.