JPS58100431A - Plasma etching method and device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (7) Field of the Invention The present invention relates to a plasma etching method and apparatus, and more particularly to a plasma etching method and apparatus used for submicron processing.

(2) Background of the technology When manufacturing semiconductor devices with submicron patterns such as VLSIs, in plasma processing and processing, side
It is extremely important to minimize damage caused by etching and ion bombardment.

Kabuto Prior Art and Problems A typical conventional etching method that causes less side etching is the reactive ion etching method.

In the reactive ion etching method, IKI
As shown in the schematic cross-sectional view of the apparatus shown in the figure, a substrate to be processed 5 is placed on a target electrode 4 disposed in an etching chamber 3 having a etching gas inlet 1 and a vacuum exhaust port 2;
Plasma 7 is generated by maintaining an etching gas pressure of about 10 to 10 (7 orr) in the etching chamber 3 and applying high frequency RF of about 0.3 to 2 (KW) between the target electrode 4 and counter electrode 6. Then, the surface of the substrate 5 to be processed is etched by the ions and radicals of the etching gas excited and formed by the plasma. In the reactive ion etching method, the substrate to be processed 5
The etching gas ions are given directionality by an electric field perpendicular to the substrate surface, which is formed on the top of the substrate.
Etching amount decreases.

However, in the above-mentioned reactive ion etching, since etching is performed in high temperature plasma,
Side etching of about 0.2 to 0.3 [μm] caused by the thermal movement of etching gas ions and radicals, and the impact of etching chamber gas ions accelerated by high voltage as described above. 0,5 generated on the processed substrate surface
There is a problem in that damage capes with a depth of about [μm] cannot be avoided.

And these problems are common to conventional conductor integrated circuit devices (ICs).
), etc., this was not so much of a problem, but in VLSI devices that require submicron patterns, it becomes a major cause of deterioration of performance and manufacturing yield.

In addition, as a method to extremely reduce the amount of etching, only charged ions are separated and extracted from the plasma using a magnetic field, and the ions are given directionality by the magnetic field to collide with the substrate to be processed. There is also an ion shower method that performs reactive etching, but this method has the problem that the etching speed is slow because etching is performed only by ions in the etching gas excited by plasma, and there is also the problem of reactive ion・Since the gas pressure in the etching chamber is lowered by one order of magnitude than in the etching method, there is a problem in that the distance over which ions can move increases, resulting in greater damage to the surface to be etched.

B) Purpose of the Invention The purpose of the present invention is to address the above-mentioned problems, and to provide a plasma etching method that has extremely low side etching, amount of etching, and amount of damage to the surface to be etched, and has an etching speed comparable to that of reactive ion etching. - To provide an etching method and device.

(2) Structure of the Invention That is, the present invention cools an etching gas excited by plasma to an extremely low temperature, and creates an energy field perpendicular to the surface to be etched, which is provided in the vicinity of the surface to be etched in the crease and lengthening gas. A plasma etching method characterized in that etching is performed through plasma etching, a means for generating high-density plasma in an etching gas for performing the plasma etching, and a means for generating high-density plasma in an etching gas excited by the high-density plasma. It is characterized by comprising means for cooling to an extremely low temperature by the Joule-Thomson effect, and means for applying a force to the processing ions contained in the excited etching gas at the extremely low temperature in a direction perpendicular to the surface to be etched. This invention relates to a plasma etching apparatus.

φ) Embodiments of the Invention The present invention will be described in detail below with reference to embodiments of the present invention using a schematic cross-sectional view of an embodiment of the apparatus shown in FIG.

For example, as shown in FIG. 2, the glass i-etching apparatus of the present invention has an etching gas inlet 11 and a vacuum exhaust port 12, and has a microwave (μ) It consists of a vacuum container 14 having a transparent window 13. The inside of the vacuum container 14 is divided into a plasma generation chamber 15 and an etching chamber 16, and a barrier 17 separating these chambers is provided with a gas ejection hole 19 having a desired diameter and a shutter 18. There is. Further, an opening of the waveguide 20 is installed above the μ-wave transmission window 13 of the plasma generation chamber 15. Further, a target electrode 22 whose pillar portion is led out to the outside through an insulating pusher 21 is disposed in the etching chamber 16, and a plate 23 is provided in the vicinity of the upper part of the target electrode 22. It is arranged. (24 in the figure indicates heat retention).

For example, when selectively etching a silicon (8i) substrate using the plasma etching apparatus of the present invention,
Processed S made of a striped film tube formed by photoresist etc.
The I substrate 25 is placed on the target electrode 22, and the inside of the plasma generation chamber 15 and etching chamber 16 is heated to 10 (Tor).
After evacuation to the extent of r), the shutter 18 between the plasma generation chamber 15 and the etching chamber 16 is closed, and the plasma generation chamber 15 is
For example, 20 [cc/min] as a cutting gas.
Carbon tetrafluoride (CF4) gas is introduced in an amount of about a minute, and the shutter 18 is opened intermittently to eject a desired amount of CF4 gas into the etching chamber 16 in a pulsed manner.
While maintaining the pressure in the generation chamber 15 at 1 to several Torr (l), the wrinkled CF4 gas is heated to several (GHz) through the waveguide 20.
・Irradiate the plasma generation chamber 15 with a μ wave of about 1
A high-density plasma (P) is generated within the chamber to excite the CF4 gas. At this time, the pressure inside the etching chamber 16 is determined by the balance between the excited 9 cF4 gas ejected from the plasma generation chamber 15 through the gas ejection hole 19 and the vacuum exhaust. The pressure is adjusted to about +10-” to 10 (Torr). Then, the grid 23 is grounded (G), and the grid 23 is grounded (G).
A negative DC bias (E) of several volts is applied to the target electrode 22 with respect to the target electrode 23, and etching is performed in good condition.

In the etching process described above, ions (CFg, etc.) and radicals (CF, etc.) that are excited by the high-density plasma and contribute to etching are formed in the CF4 gas in the Prada 1 generated nitrogen 15 at a high density.

CF4 containing these ions and radicals at high density
The gas flows through the gas ejection hole 19 at a rate of several hundredths to several hundredths.
Etching chamber 16 with low pressure of 1/000 root change
It is intermittently ejected into the interior, expands adiabatically, and is cooled to an extremely low temperature by the George-Thomson effect. It is desirable that the above cooling be carried out to a temperature close to the liquefaction temperature of the quenching gas.
In the case of the above-mentioned CF4 gas, about -120C''C'l is appropriate.

The etching chamber I6 is filled with the CF4 gas cooled to an extremely low temperature at a pressure of about 10 to 10.

In such extremely low temperature CF4 gas, the thermal movement of ions (CF, etc.) and radicals (CF4, etc.) that contribute to etching is almost stopped.

Therefore, the ions (CF, etc.) are
The radicals (
The CF, etc.) is aligned by gravity so that its surface is perpendicular to the surface of the 11th substrate, and etching is performed by colliding with the surface of the 81 substrate to be processed at a gentle speed given by the weak electric field 1 gravity, etc. reactor.

Note that the means for imparting directionality to the velocity of ions is not limited to the above-mentioned electrostatic field, but may also be a quiet magnetic field or a high-frequency electromagnetic field.

q) Effects of the Invention As shown in the above embodiments, in the present invention, the surface of the substrate to be processed is etched by the ions and radicals of the etching gas that collide perpendicularly without being disturbed by thermal motion. Therefore, the amount of side etching is significantly reduced compared to the conventional method, and can be suppressed to 0.1 [μm] or less. In addition, the speed at which ions and radicals collide with the surface of the substrate to be processed is extremely slow, so the depth of damage inflicted on the surface of the substrate to be processed can be reduced to several 100 (X) or less. Since damage is reduced, the mask film can be formed thinner, and pattern accuracy can also be improved in this respect.

As explained above, according to the present invention, it is possible to improve etching accuracy and reduce etching damage, thereby making it possible to process submicron patterns.

In the present invention, since radicals also contribute to etching as described above, the etching rate is not inferior to reactive ion etching.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of an active ion etching device, and FIG. 2 is a schematic cross-sectional view of an active ion etching device. FIG. 2 is a schematic cross-sectional view of an embodiment of a cutting device. In the figure, 11 is an etching gas inlet, 12 is a vacuum exhaust port, 13 is a microwave transmission window, 14 is a vacuum container, 1
5 is a plasma generation chamber, 16 is an etching chamber, 17 is a barrier, 18 is a shutter, 19 is a gas ejection hole, 20 is a waveguide,
21Fi insulation block, 1.22 is target electrode, 23d
24 is a grid, 25't is a silicon substrate to be processed, P is plasma, G is grounding, and E is a negative bias.

Claims (1)

[Claims] 1. A plus i characterized by being excited by plasma and performing etching through a cooling field at an extremely low temperature.
・Methods of engineering and ching. 2. means for generating high-density plasma in the etching gas; means for cooling the etching gas excited by the high-density plasma to a cryogenic temperature by the Joule-Thomson effect; 1. A plasma etching apparatus comprising: means for applying a force to process ions perpendicular to a surface to be etched.