JPS58185773A - Dry etching method - Google Patents

Abstract

PURPOSE:To reduce the time for exchanging sample between each etching in a high-speed dry etching device, by deviating the off-timing between the high voltage to be applied on electrostatic chucking electrodes for the sample and the high-frequency electric power to be applied between a cathode and an anode. CONSTITUTION:A sample 19 is chucked and etched by using an electrostatic chucking mechanism 18 of a high-speed dry etching device utilizing magnetron electric discharge. A sample 24 is placed on an insulation film 23 on symmetrical semicircular electrodes 22 on a sapphire substrate 21 of the mechanism 18 and when a high voltage is applied between the electrodes 22a and 22b, the sample 24 is chucked. High-frequency electric power is applied between a cathode 12 and the anode 4 of a vcacuum vessel to generate electric discharge plasma between both electrodes, then magnetron discharge 17 is induced and the sample is etched by the same. The sample 24 here is removed from the mechanism 19 after the high voltage applied to the electrode 22 is first turned off while the discharge 17 is maintained, then the highfrequency electric power applied between the cathode 12 and the anode 4 is turned off.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for dry etching a sample using a dry ear etching device equipped with an electrostatic chuck mechanism.

[Technical background of the invention and its problems]

In recent years, integrated circuits have become increasingly miniaturized, and even ultra-LSIs with minimum dimensions of 1 to 2 [μm] have recently been prototyped. Such microfabrication is usually done using a reaction system with parallel plate electrodes. A reactive gas such as CF4 is introduced into the container, and high-frequency power (for example, 13.56M) is applied to the electrode on which the sample is placed.
Hz) f is applied to generate a glow discharge.
Positive ions in plasma are used as cathode (electrode for applying high frequency power)
Reactive ion etching (R@aet
lv*ION Etching; RIE) is used. However, RI using this parallel plate electrode
In E, for example, the etching rate of 5ft using CF No. 10H gas is at most 300 to 400 (X/m1n), and the etching rate of 810. It takes about 40 minutes for etching, which is extremely inconvenient in terms of mass production. Therefore, it is desired to increase the etching speed.

To improve the etching speed, for example, increase the RF power. However, in this case, conversely, the loss due to the conversion of RF power into heat increases the deterioration and deterioration of the eliphotoresist, and the increase in tvDC results in further damage to the device. Therefore, the current situation is to address these problems by reducing the 1F power as much as possible. The essential cause of this is that the ionization efficiency of the introduced gas is extremely low at 1 [-] or less at the glow discharge voltage caused by RF.

On the other hand, the inventors of the present invention have recently developed a method to replace RF glow discharge by providing a magnetic field generating means consisting of a permanent magnet under the RF-applied electrode, forming a magnetic field perpendicular to the electric field caused by the RF power, and generating electrons. Drifting motion in the electric field) x (magnetic field) direction, creating a closed circuit for electron orbits in parentheses, promotes collisional dissociation between electrons and gas molecules and improves discharge efficiency.A dry etching device using nine magnetron discharges. Proposed(
(Japanese Patent Application No. 173821/1982).

Figure s1 is a schematic diagram showing a dry etching apparatus using the magnetron discharge described above.

Gas inlet 1, exhaust system 2.3 and vacuum.

In the cutting 4, there is a room 8 in which a part m6 that generates glow discharge 5 and a magnet assembly (magnetic field generating means) 7 are arranged.
The high frequency power 9 is passed through the matching box 10, the water cooling pipe 11 [combined cathode 12 and the pulp 13].
It's divided into sections. The etching process is carried out as follows. First, the nine-threaded rod 15 is rotated from the outside of the vacuum container 4 by the rotation introducing machine J4, and moves downward according to the pulp 131jf guide 16, and the pulp 13 is opened. Next, both parts Ill and 8 are connected to 10"-' (Tor) by the exhaust system 3.
r) Exhausted below.

When the pressure is exhausted to below 10"-' (Torr), the pulp 13 closes in the reverse operation, dividing both chambers by 6.8f. Then, the reaction gas is introduced through the gas inlet 1 and at the same time the exhaust system 2 The pressure is controlled to be in the range of 10-1 to 1 o-'' (minorr),
When high frequency power 9 is applied to cathode 12, magnetron discharge 17 is generated by the orthogonal electromagnetic field of KXB, resulting in etching of material to be etched (sample) 19 such as an St wafer of an electrostatic chuck mechanism to be described later. The magnetic pole gaps between the N and S poles of the permanent magnets 7a, 7b, and 7e are rectangular and form a closed loop. On the other hand, when the magnet assembly 1 is scanned by the rotation introducing system 20 such as a motor as in FIG. 1, the path of the magnetron discharge 17 scans over the material 19 to be etched, and etches uniformly.

At this time, since the chamber 1 is maintained at a pressure of 10''-' (Torr), no discharge occurs and the material to be etched 19
However, the same etching speed can be obtained with half the high-frequency power shown in Figure 1. That is, in FIG. 1, with the pulp 131f open, 5X1G-"
When halogen yttx, for example CHFa gas [is introduced and etched with s + o = 2, the result obtained from an etching rate of about 7000 (X/min) with the application of high frequency power of 300 (W) is obtained by closing the pulp 139f and etching it with s + o = 2. When only room C was discharged using the method described above, the same etching speed was obtained by applying a high frequency power of 150 (W).Not only did the etching speed improve, but also the heat loss was reduced due to the high frequency power r being 810 (W). ．There was no or very little damage to the resist that served as the upper mask.

The high-speed RIB method that is the basis of this proposal is to make the etching equipment of production equipment, which is becoming larger in diameter to 5 inches and 6 inches with the miniaturization of ultra-LSIs, to improve mass production and miniaturize the etching equipment.
In other words, at the conventionally low etching speed, it is necessary to etch as many sea urchins as possible in patches for mass production, and for this purpose, the RIE equipment has to be made into a standard. However, high-speed etching can be mass-produced by processing only one or a small number of etching sheets, the equipment can be downsized, and it does not take up much floor space r of a clean room where purity must be maintained.

As explained above, the high-speed dry etching apparatus shown in Figure 1 The time it takes to attach and detach the chuck system is an important factor that greatly reduces mass productivity! It turned out to be. FIGS. 2(a) and 2(b) show the electrostatic chuck mechanism 18, and FIG. 2(a) is a plan view,
FIG. 2(b) is a view of arrow A-AIIFr in FIG. 2(&). Inko 21 is, for example, a Naphire substrate, and semicircular electrostatic electrodes 22h and 22b are symmetrically formed on this substrate zl. Moreover, the electrode 22a.

An insulating film 23 such as Mi 2 is deposited on 22b.

A sample (dielectric material) 24 corresponding to the object to be etched 19 is placed on this insulating film 23.

In the electrostatic chuck mechanism constructed in this manner, when a high voltage of about < 1 (Kv) is applied between the electrodes 22g and 22b as shown in FIG. 22! It comes out straight from L and enters the sample 24, and in the case of a material with low electrical resistance like an Sl wafer, it is 1, and no electric field is generated in the sample 24, and the electric field comes out from the side opposite to the electric field 22b and goes straight into 22b. You can think of it as entering. The magnitude of the attractive force at that time is proportional to the square of the applied voltage, and
1i) zatro" (2) 2(lffli""f, B,
n & □ are known. That is, the larger the applied voltage, the greater the attraction force, and
.

The greater the O contact between the metal body and the metal body 22b, the stronger the force will be applied to the chuck.
This is the haze that was obtained by investigating the time until the test drop when the high voltage was turned off. As a result, even when the high voltage was turned off, the sample 24 rarely fell due to its own weight, and 1
In other words, this experimental fact suggests that the dipole OIi induced in the insulating film 23 of the microphone, etc., always has a long open time.
In actual etching, at the same time as the etching of the sample 14 is completed, the sample 24 must be quickly replaced with the sample to be etched next. At present, it is necessary to provide some kind of forcing means for this sample exchange. →Reduces damage. For example, see Haruo Okano, Takashi Yamazaki, Hiro Ikehata, 3rd Dry Process V posicum, P2O (1981) Institute of Electrical Engineers of Japan)
[To ensure this, the thickness of the water-cooled cathode 12 is very thin, less than 4 mm, and therefore it is extremely difficult to provide the external means by machining or the like. In this way, as shown in Figure 1, high-speed etching of the object to be etched can be achieved by using an etching device that applies a magnetic field.However, when considering the entire system, the extremely long relaxation time mentioned above is required for mass production. [Objective of the Invention] An object of the present invention is to reduce the amount of sample etch between each etching process when chucking a sample and etching the sample using an electrostatic chuck mechanism. An object of the present invention is to provide a dry etching method that allows for quick replacement of parts and improves productivity. The gist of the present invention is to shorten the aforementioned relaxation time by shifting the OFF timing between the high voltage applied to the electrostatic chuck electrode and the high frequency power applied between the cathode and the anode.

The inventors of the present invention discovered the following important fact by performing the following experiment in the plasma shown in FIG. 1, as described in FIG. 4 above. That is, first, the high frequency power is turned off, and then the high voltage is applied to the electrostatic chuck electrode. [When turned off, the time until the sample falls is 1 to 2 days, as in the case of Diagram 4! However, on the contrary, it was found that by delaying the timing of turning off the high-frequency power [later than the turning off of the high voltage applied to the electrostatic chuck electrode], the sample would fall instantaneously.The details of this cause are as follows. At present, it has not been completely elucidated, but it is probably <13.56 (M
Hz) is sufficiently lower than the dielectric relaxation frequency of the insulating film of the two groups, the rotation of the oriented molecules constituting the above-mentioned absolute i**v occurs smoothly, and the boundary of molecular rotation following the high frequency electric field It is assumed that the sample falls instantaneously.

When a force is applied, a sample is placed on the surface of the cathode.
A magnetic field [applied magnet and this magnet] is applied to the surface of the cathode by a closed-loop magnetic pole gap provided on the back surface of the cathode? means for scanning in a direction perpendicular to the direction of the electric field generated by the high-frequency power; means for shielding a space in which the magnet is arranged from a space in which the sample is arranged; a plurality of mutually insulated electrodes; A dry etching device comprising an insulating film deposited on the surface of the cathode and an electrostatic chuck mechanism, and means for applying a high voltage between each electrode of the electrostatic chuck mechanism. When etching is completed, a high voltage t- applied to the electrode of the electrostatic chuck mechanism is first applied to the electrode of the electrostatic chuck mechanism. 0FF, and then high-frequency power 5 applied to the cathode, anode, and 0
orr1. This is the second son's method, in which the sample is removed from the electrostatic chuck mechanism.

〔Effect of the invention〕

According to the present invention, the sample chucked in the electrostatic chuck mechanism is removed by applying a high voltage t-0FF to the electrode of the electrostatic chuck mechanism and then turning off the high-frequency power 1j-OFF applied between the cathode and the anode. can be quickly removed from the t-yuck mechanism. Thanks to this, sample exchange can be done quickly, and the overall productivity can be greatly improved by etching. Further, there is an advantage that it can be realized extremely easily by simply setting the OFF timing of the high voltage and high frequency power without using any special members.

[Embodiments of the invention]

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

Figure 5-) to (,) are O timing charts for explaining one embodiment of the present invention.0 Figure 5-) is the above-mentioned jI1
The relationship between the scanning speed V and time t of the permanent magnet 71~re() unidirectional scan in the figure, the relationship between the high frequency power P and time t in the figure (b), and the relationship between the high frequency power P and time t in the figure (,) the voltage applied to the electrostatic electrode In this embodiment, first, at the etching end point A, as shown in FIG.
After turning off, the permanent magnets 1a to 7C are scanned in one direction and high frequency power is applied in the state 111 for at least lf cycles, and then, for example, at point B, the high frequency power is turned off and a single wafer (sample) is turned off. All Etsutenge 11 [End. By assembling such an etching sequence, it is possible to quickly exchange wafers between each etching process, and therefore an etching apparatus and an etching apparatus that can process one or a small number of wafers using a small lid can be realized. Note that the time delay between point A and point B is due to the permanent magnet 7.
It has been confirmed that a scan half cycle of a to 7c is sufficient.0 Note that the present invention is not limited to the above-mentioned embodiments, and the l! It can be implemented with various modifications without departing from the above. For example, the OFF timing shift time between the high voltage applied to the electrostatic chuck electrode and the high frequency voltage applied between the cathode and the anode may vary as appropriate depending on the specifications. Additionally, the configuration of the electrostatic chuck mechanism can be changed as appropriate depending on specifications. Furthermore, there is a dry etching device using magneto discharge.
Of course, the present invention can be applied to a dry etching apparatus that normally utilizes an O gas discharge.

[Brief explanation of drawings]

Figure 1 is a schematic configuration diagram showing a high-speed dry etching device using magnetron discharge, Figure 2 (a) e Cb
)) is the electrostatic chuck mechanism used in the above device. Figs. Use example
Figures (a) to (c) are timing charts for explaining one embodiment of the present invention. 1... Gas inlet, 2, 3... Exhaust system, 4-mount vacuum container (anode), 5... Glow discharge, 6... Vacuum house, 1...
... Magnet assembly, 8... High vacuum chamber of 10"-' (minorr) or less, 9... High frequency power supply, 10.
...Matching circuit, 11...Water cooling pipe, 12...
・Cathode, IS...Gate valve, 14...Solenoid valve, 16
... Threaded rod, 16... Guide, 12.° Magnetron discharge, 18... Electrostatic chuck mechanism, 19.24.
...Edited object (sample), 20...Motor, 21
... ° Sapphire, 32@, 22k ... Electrostatic electrode, 2
3...Insulating film. Applicant's agent Patent attorney Takehiko Suzue 112 (a) (b) No. 3-■ No. 4g%ij

Claims (1)

[Claims] A vacuum vessel comprising a cathode to which high-frequency power is applied and a sample placed on the surface thereof, and a secondary anode disposed opposite to the surface of the cathode, and a reaction gas introduced into the vacuum vessel. means for applying a magnetic field to the surface of the cathode through a closed-loop magnetic pole gap provided on the back surface of the cathode; means for shielding the space in which the sample is placed from the space in which the sample is placed; a plurality of nine electrodes insulated from each other and an insulating film deposited on the electrodes; An electrostatic chuck mechanism, means for applying a high voltage between each electrode of the electrostatic chuck mechanism, and a dry etching device are used to generate discharge plasma between the cathode and anode and to generate a magnetron discharge. The sample t
In the dry etching method, when the etching of the sample is finished and at the 9th point, the magnetron discharge is maintained and then applied to each electrode of the electrostatic chuck mechanism, and then the high voltage is set to 10FF, and then the A dry etching method characterized in that the sample is removed from the electrostatic chuck mechanism by applying high frequency power 1jOFFl between the cathode and the anode.