JPH01189126A - Etching apparatus - Google Patents

Abstract

PURPOSE:To increase the life of electrodes to be stabilized, to automate an apparatus, and to improve its productivity by forming an insulating layer having a predetermined resistance value or more on the face of at least one electrode in contact with plasma chlorine series gas. CONSTITUTION:A vacuum vessel 1 is opened, and receives a semiconductor substrate 12 conveyed on a lifting pin 18 raised by a pin elevating mechanism 17, the pin 18 is moved down to place the substrate 12 on a polymer film on a lower electrode 11, a clamp ring 13 is moved down by a ring elevating mechanism 15, and the substrate 12 is press-bonded. The vessel 1 is evacuated, and an upper electrode 4 is moved down by an electrode elevating mechanism 2. Chlorine series reaction gas is supplied from a supply pipe 5 to the electrode 4, fed from pores on the lower face of the electrode 4, a high frequency voltage is applied from a power source 6 to the electrode 4 to generate a plasma, thereby etching the substrate 12. The face of the base material of the electrode 4 in contact with the plasma chlorine gas of the aluminum layer is formed of an alumina layer having 900MOMEGA of insulation resistance, thereby providing a long life and high stability.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to an etching apparatus.

(Conventional technology) In recent years, the complicated manufacturing process of semiconductor devices has been simplified.

Plasma etching equipment that utilizes reactive components in gas plasma is attracting attention as an etching equipment for various thin films that can automate processes and form fine patterns with high precision.

This plasma etching apparatus converts a reactive gas, such as argon gas, introduced into a reaction tank into plasma by applying high frequency power to a pair of electrodes placed in the reaction tank, such as high frequency electrodes. This is an apparatus that etches a substrate, such as a semiconductor wafer, using the active ingredients contained therein.

In such conventional etching equipment, alumite electrodes that can perform stable discharge even at high temperatures are used to etch Po1y-5iWX, metal silicide films, nitride films, etc. using chlorine-based gas. This alumite electrode is also gradually consumed as aluminum chloride during the etching process.

When the electrode reached the end of its life, it was replaced.

(Problem to be solved by the invention) However, even if there are no differences in size, shape, alumina film thickness, etc., alumite electrodes do not have a constant lifespan, and the electrodes must be replaced irregularly. It is necessary to monitor the state of the semiconductor wafer after the etching process and confirm the stability of the etching process, which poses the problem of not being able to be automated.

Also, the lifespan of anodized aluminum electrodes is too short.

The problem is that the electrodes must be replaced frequently, and the device must be stopped for maintenance each time, which reduces the operating efficiency of the device and reduces productivity.

The present invention has been made in view of the above-mentioned problems, and provides an etching apparatus that has a longer and more stable electrode life, is compatible with automation, and has improved operating efficiency and productivity.

[Structure of the invention]

(Means for Solving the Problems) The surface of at least one of the electrodes that comes into contact with at least plasma-formed chlorine-based gas is an insulating layer having an insulation resistance of 900 MΩ or more.

(Function) In the etching apparatus of the present invention, the surface of at least one of the electrodes that comes into contact with plasma-formed chlorine-based gas is an insulating layer having an insulation resistance of 900 MΩ or more, so that the electrode is eroded by the chlorine-based gas as aluminum chloride. By reducing the amount of engraved parts, the electrode can be used stably for a long time, and the life of the electrode is stabilized to a certain level, so even if there is no human supervision, the life of the electrode is guaranteed for a certain processing time, making it compatible with automation. It has become possible. Furthermore, since the electrodes have a stable and long service life, the maintenance cycle for electrode replacement can be extended.

(Example) Hereinafter, five examples in which the apparatus of the present invention is applied to a semiconductor manufacturing process will be described with reference to the drawings.

In the upper part of the cylindrical vacuum container (1) made by Affi and whose surface is alumite-treated, an electrode lifting mechanism (2) (for example, an air cylinder, a ball screw, etc., and an upper electrode that can be moved up and down via a connecting rod (2)) is provided. This upper electrode (a) is made of AQ and has a flat plate shape with an alumite treatment on the surface, and is supplied with a reaction gas for introducing a chlorine-based reaction gas such as carbon tetrachloride or boron trichloride from a gas supply source (not shown). Connected to pipe 0.

In addition, a large number of small holes (not shown) are provided on the lower surface of the upper electrode, through which the reaction gas can flow out into the vacuum vessel ω. Moreover, the upper electrode (A) is connected to a high frequency power source (0) with a power of 500 W and a frequency of about 13 MHz for plasma generation, and the upper electrode (A)
On the upper side, there is a disk-shaped upper electrode cooling block (2) that can circulate a cooling liquid from a cooling liquid circulator (not shown) through a cooling liquid pipe (2) so that the upper electrode can be cooled with a cooling liquid such as water. 8) is provided.

Here, on the surface of the upper electrode (a) that comes into contact with the chlorine-based gas turned into plasma, an alumina layer, which is an insulating layer having an insulation resistance of 900 MΩ or more, is formed by alumite treatment.

At the bottom of the vacuum container (2), there is a disk-shaped lower electrode cooling block (2) that can circulate a coolant, such as water, from a coolant circulator (not shown) to the upper electrode (2) through a coolant pipe (3). 10) is provided so as to be in contact with the upper surface of the lower electrode cooling block (10).

The flat lower mold is made of A2g and has an alumite treatment on the surface! (11) is installed, and this lower electrode (11
) is grounded.

Here, the vacuum container ω can be opened and closed by an opening/closing mechanism (not shown), such as a gate valve mechanism, etc., and an object to be processed, such as a semiconductor substrate (12), is transported inside by a transport mechanism (not shown), such as a hand arm, and the lower electrode A semiconductor substrate (12) can be placed on (11). Moreover, the vacuum container (υ) becomes airtight when an opening/closing mechanism (not shown) is closed, and the interior can be brought to a desired vacuum state, for example, from several tens of mTorr to several tens of Torr, using a vacuum pump (not shown).Here, If a transport mechanism (not shown) is installed in the vacuum preliminary chamber and is airtightly connected to the vacuum container (2), the time required to bring the inside of the vacuum container (ω) to the desired degree of vacuum using a vacuum pump (not shown) after transporting the semiconductor substrate (12) can be shortened. .

Then, on the upper outer periphery of the lower electrode (11), there is a clamp ring (13) whose surface is anodized with illumination, which can compress the outer periphery of the mounted semiconductor substrate (12) onto the lower electrode (II). Ring elevator 4i1 via connecting rod (14)! (15) For example, it is installed so that it can be raised and lowered using an air cylinder or the like. Also, inside the lower electrode (11) near the center, a pin elevating mechanism (17), for example, an air For example, three SUS lift pins (18) connected to a cylinder or the like are provided.

This lift pin (18) is inserted into the lower electrode (11) using a part of the hole (19) bored in the lower electrode (11). The hole (19) is connected to a cooling gas supply pipe (20) so that a cooling gas such as helium gas from a cooling gas supply source (not shown) can be supplied to the m-plane of the semiconductor substrate (12).

Here, the semiconductor substrate (12) mounting surface of the lower electrode (11) assumes that the force applied to the semiconductor substrate (12) by the clamp ring (13) is applied to the semiconductor substrate (12) as a uniformly distributed load. It is formed into a convex shape so as to follow the deformation curve of the semiconductor substrate (12) at the time.

Further, between the lower electrode (11) and the semiconductor substrate (12) mounting surface, the impedance between the semiconductor substrate (12) and the electrode that holds this semiconductor substrate (12), that is, the lower electrode (11) is made uniform. Similarly, a synthetic polymer film (21), for example, a heat-resistant polyimide resin with a thickness of about 20 μm to 100 μs, is adhered to the semiconductor substrate (12) mounting surface of the lower electrode (11) with a heat-resistant acrylic resin adhesive. It is established by

Between the outer periphery of the lower electrode (11) and the vacuum vessel 0, there are many exhaust holes (23 ) is provided.

Here, the semiconductor substrate (12) held on the lower electrode (11)
) An insulating shield ring (25) made of, for example, tetrafluoroethylene resin is provided on the outer periphery of the upper electrode (a) so that plasma can be generated to approximately the same size as the upper electrode (a).

Further, the etching apparatus having the above structure is controlled in operation and setting by a control section (not shown).

Next, the semiconductor substrate (12
) etching method will be explained.

First, open the vacuum container (1) using an opening/closing mechanism (not shown), and place the semiconductor substrate (12) transported by a transport mechanism (not shown) on the lift pin (18) raised by the pin lifting mechanism (17) and the connecting part (16). take. After this, lift pin (18
) to place the semiconductor substrate (12) on the lower electrode (11), and lower the clamp ring (13) that had been raised by the ring lifting mechanism (15) and connecting rod (14).
The semiconductor substrate (12) is crimped onto the lower electrode (11).

At this time, the opening/closing mechanism (not shown) of the vacuum container (2) has already been closed, and the interior of the vacuum container (ω) is brought to a desired vacuum state by a vacuum pump (not shown).

Then, the upper electrode (
A) is lowered, and the electrode interval with the lower electrode (11) is set to a desired interval, for example, about several I.

Next, a chlorine-based reactive gas such as boron trichloride is supplied from a gas supply source (not shown) to the upper electrode (a) through the gas supply pipe It flows out into the vacuum container ω. At the same time, a high frequency voltage is applied to the upper electrode (a) by the high frequency power supply 0, plasma is generated between it and the grounded lower electrode (11), and this plasma is used to generate the semiconductor substrate (
12) is etched.

Here, as shown in FIG. 2 when viewed microscopically, the upper electrode (upper electrode) has an insulation resistance of 90% at least on the surface of the base material aluminum layer (27) that comes into contact with the plasma-formed chlorine gas.
An alumina layer (28), which is an insulating layer with a resistance of 0 MΩ or more, is formed by alumite treatment. This alumina layer (28
) has a film thickness of about 50-70 μs and an insulation resistance of 9
00MΩ/500V or more, but even if the dimensions, shape, film thickness, etc. are the same in appearance, the insulation resistance is 900MΩ/5
If it is lower than 00V, the alumina layer (28) on the surface is etched unstablely by chlorine atom radicals in the chlorine-based gas that has turned into plasma, producing aluminum chloride, and the life of the alumina layer (28) is shortened, for example, by the semiconductor substrate. (12) The number of wafers processed varies from 750 to 2,250 wafers, and the upper electrode (to), which has reached the end of its life, generates an abnormal discharge and the semiconductor substrate (12)
Due to the damage caused to the alumina layer (28), the electrode had to be replaced irregularly as the alumina layer (28) reached the end of its life. However, alumina is an insulating layer! The insulation resistance of (28) is 90
Since the value is 0 MΩ or more, the alumina layer (28) is etched by chlorine atom radicals in the chlorine-based gas that has turned into plasma, and the reaction that produces aluminum chloride can be stably slowed down, so the life of the alumina layer (28) is, for example, Semiconductor substrate (
12) Stabilization occurs when the number of sheets processed is 2250 or more. This eliminates the need for humans to constantly monitor the stability of the etching process, allowing for automation. Furthermore, since the life of the upper electrode (a) is extended and stabilized, the frequency of replacement of the upper electrode (a) can be reduced, and maintenance time can be shortened, thereby improving the operating efficiency and productivity of the device.

For example, vacuum level 0.15 Torr, high frequency power supply power 50
0w.

CCV, + He gas flow ft 200cc/min,
Upper electrode) temperature 20℃, lower electrode temperature 25℃ or less, upper electrode ■ Alumina layer (28) film thickness 60. When , the insulation resistance of the upper electrode (a) alumina layer (28) and (7) is 10 to 3.
00MΩ1500V on the upper electrode) The lifespan is approximately 750 semiconductor substrates (12) processed.
The insulation resistance of the alumina layer (28) on the upper electrode is 900M.
When Ω was set to 1500 V, the life span of the upper electrode (up to) was 2250 or more semiconductor substrates (12) processed.

Even though the appearance of the alumina layer (28), such as the film thickness, is the same.

The insulation resistance of the insulation layer, that is, the alumina layer (28) is 900MΩ
If the variation is smaller, the life of the upper electrode (a) will be short and unstable, and the insulation resistance of the alumina layer (28) will be 90%.
If it is set to 0 Ω or more, the life of the upper electrode (in the upper electrode) will be long and stable. This fact has been confirmed by the inventor through numerous experiments.

At this time, the semiconductor substrate (12) is attached to the clamp ring (13).
However, due to microscopic surface roughness, the lower electrode (11) is crimped as shown in Figure 3.
A gap (30) exists between the semiconductor substrate (12) and the semiconductor substrate (12). Although the impedance between the semiconductor substrate (12) and the lower electrode (11) due to this gap (30) is small, it is not uniform and has large variations. In addition, since the insulating layer made of alumite on the surface of the lower electrode (11) is porous, the semiconductor substrate (
12) and the lower electrode (11) becomes worse. However, as shown in FIG. 3, as a means to make the impedance uniform between the semiconductor substrate (12) and the electrode holding the semiconductor substrate (12), that is, the lower electrode (11), 11) A synthetic polymer film (21) is provided between them, for example, with a thickness of 2
A heat-resistant polyimide resin having a thickness of about 0/jfll-100 μs was adhered to the lower electrode (11) with a heat-resistant acrylic resin adhesive having a thickness of about 25 μs. Since the impedance of the synthetic polymer film (21) between this gap (30) and the lower electrode (11) is sufficiently larger than the impedance of the gap (30), the impedance between the semiconductor substrate (12) and the lower electrode (11) is Since the variation can be reduced, this impedance can be made uniform and uniform. Also,
The synthetic polymer film (21) is not porous like alumite, so it has good contact with the semiconductor substrate (12).
This also has the effect of reducing variations in the air gap (30) and improving the uniformity of the impedance of the air gap (30).

With these, the semiconductor substrate (12) and the lower electrode (11)
The impedance between them becomes uniform, thereby improving the uniformity of etching of the semiconductor substrate (12).

Here, the degree of vacuum is 2.4 Torr, the high frequency power source (e power 5
00υ, preion gas flow rate 80cc/win, argon gas flow rate 500cc/win, upper electrode (a) temperature 2
When the lower electrode (11) temperature is 8°C or less, a 25μs thick alumite insulating film is deposited on the lower electrode (11) with a 15μs insulating film thickness.
25-μm thick through μs heat-resistant acrylic resin adhesive
FIG. 4 shows the number of synthetic polymer films (21), etching speed, and etching uniformity when heat-resistant polyimide resin, which is the synthetic polymer film (21), is adhered. From FIG. 4, it is clear that the etching rate is well within the practical range and that the uniformity of etching is significantly improved. In addition, since the synthetic polymer film (21) is a stable material with a dense surface, it can prevent abnormal discharge due to variations in impedance of the void (30), and damage to the semiconductor substrate (12) due to abnormal discharge can be prevented. It is possible to perform stable etching processing without any problems.

During the etching process, a cooling liquid from a cooling liquid circulator (not shown) is passed through the cooling pipes (7, 9), the upper electrode cooling block (2), and the lower electrode cooling block (10).
Cooling the upper electrode (a) and the lower electrode (11) to a desired temperature improves the etching rate. Further, a cooling gas from a cooling gas supply source (not shown) is supplied between the semiconductor substrate (12) and the synthetic polymer film (21) through the cooling gas supply pipe (20) and the hole (19) at a predetermined pressure and flow rate, for example. Semiconductor substrate (12) 1
Cooling the surface improves the temperature uniformity of the semiconductor substrate (12), which results in improved etching uniformity.

Additionally, an insulating shield ring (25) provided on the outer periphery of the upper electrode (a) and an insulating clamp ring (13) provided on the outer periphery of the lower electrode (11) allow the semiconductor substrate (12
) Since plasma can be generated in approximately the same size as the processing surface, plasma diffusion can be prevented and stable etching processing can be performed.

The treated reaction gas is then exhausted from the exhaust pipe (22) through the exhaust hole (23) of the exhaust ring (24).

Next, the vacuum container (■) is opened by an opening/closing mechanism (not shown), the clamp ring (13) and the lift pin (18) are lifted, and the semiconductor substrate (12) on the lift pin (18) is transferred by a transfer mechanism (not shown), and the operation is completed. finish.

In the above embodiment, the explanation was given using the surface of the upper electrode that comes into contact with at least the chlorine-based gas that has become plasma, but any surface of at least one electrode that comes into contact with at least the chlorine-based gas that has become plasma may be used, and the lower electrode may also be used. , may be both upper and lower electrodes, or may include an electrode surface that does not come into contact with the chlorine-based gas turned into plasma, and is not limited to the above embodiments.

Furthermore, in the above embodiment, the alumina layer of the alumite-treated AM electrode was used. It goes without saying that the layer material is not limited to the above embodiments.

Moreover, in the above embodiment, a semiconductor substrate was used as the object to be processed, but any object to be etched may be used.
al[)isplay) substrate or a glass substrate may be used.

As described above, according to this embodiment, at least one of the opposing electrodes is provided with an insulating layer having an insulation resistance of 900 MΩ or more on the surface that comes into contact with the plasma chlorine gas, and a voltage is applied between the opposing electrodes. Since the object to be processed is etched with plasma-formed chlorine-based gas, the life of the electrode can be extended and stabilized, eliminating the need to monitor the stability of the etching process, reducing the frequency of electrode replacement, and reducing maintenance time. It is possible to shorten the maintenance cycle and lengthen the maintenance cycle.

〔Effect of the invention〕

As explained above, according to the present invention, the life span of the electrode for plasma-formed chlorine-based gas is extended and stabilized, so that automation is possible and the operating efficiency and productivity of the device can be improved.

[Brief explanation of the drawing]

Figure 1 is a block diagram to explain the etching apparatus of the present invention, Figure 2 is a diagram to explain the insulating layer of the upper electrode in Figure 1, and Figure 3 is a diagram to explain the function of the synthetic polymer film in Figure 1. The explanatory diagram, FIG. 4, is a diagram showing the relationship between the etching rate and uniformity of FIG. 1 and the number of synthetic polymer films. In the figure, 11...Lower electrode 12...Bouai Houki 28
... Alumina layer patent applicant Tokyo Electron Ltd.

Claims (1)

[Claims] In an etching apparatus that applies a voltage between opposing electrodes and etches the object to be processed with plasma-turned chlorine-based gas, at least one of the electrodes has an insulation resistance of 900 M on the surface that comes into contact with the plasma-turned chlorine-based gas.
An etching device characterized by an insulating layer of Ω or more.