JPH07111965B2 - Etching equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to an etching apparatus.

(Prior Art) In recent years, as a thin film etching apparatus capable of simplifying a complicated manufacturing process of a semiconductor element, automating the process, and forming a fine pattern with high accuracy, gas plasma Attention has been paid to a plasma etching apparatus using a reaction component.

This plasma etching apparatus is a gas in which a reaction gas such as an argon gas introduced into the reaction tank is turned into plasma by applying high-frequency power to a pair of electrodes arranged in the reaction tank, for example, high-frequency electrodes. This is an apparatus for etching a substrate such as a semiconductor wafer by utilizing active components therein.

Such a conventional etching apparatus is disclosed in JP-A-61-206225.
As disclosed in the publication, a mechanism for pressing the semiconductor wafer against the convex electrode to hold the semiconductor wafer in close contact with the electrode is used to prevent dielectric breakdown of the semiconductor wafer.

(Problems to be Solved by the Invention) However, a mechanism or the like for holding a semiconductor wafer arranged around an electrode in close contact with the electrode as disclosed in JP-A-61-206225 described above generally has a high rigidity. It was necessary to use a conductive member such as a metal for some members because of necessity.

Therefore, the electric charges and ions in the plasmatized gas flow into the conductive member around the electrodes and diffuse the plasma, so that the plasmatized gas cannot be concentrated between the electrodes facing each other, and the etching rate and the etching uniformity are reduced. There was a problem that it would decrease.

The present invention has been made in consideration of the above points, and provides a stable etching apparatus that concentrates a plasmatized gas between opposed electrodes to improve etching rate and uniformity.

[Structure of Invention]

(Means for Solving the Problem) According to claim 1 of the present invention, a mounting table provided in a vacuum container for mounting an object to be processed, and an electrode provided on the mounting table and the object to be processed are disposed between the table. An electrode that generates a plasma by applying a voltage between the electrodes provided opposite to each other, a clamp ring that presses the outer peripheral portion of the object to be processed against the mounting table to hold the object, A ring elevating mechanism for elevating and lowering the clamp ring is provided, and the clamp ring is formed of a metal, and the metal is covered with an insulating member.

Further, the clamp ring is preferably made of aluminum and has a surface coated with an insulating alumina. More preferably, the electrode mounting surface provided on the mounting table for mounting the object to be processed is provided with means for insulatingly coating the conductive member.

(Operation) In the etching apparatus of the present invention, since conductive members made of metal or the like, which are provided around the electrodes facing each other due to necessity of rigidity and the like, are insulation-coated, ions and charges in the gas turned into plasma are conductive members. It is possible to prevent the gas that has been turned into a plasma and is turned into plasma, from being diffused, and the gas that has been turned into plasma can be concentrated between the opposing electrodes.

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

Cylindrical vacuum container made of Al and the surface of which is anodized (1)
An electrode elevating mechanism (2), for example, an air cylinder, a ball screw or the like and an upper electrode (4) capable of ascending and descending via a connecting rod (3) are provided in the upper part of the inside. The upper electrode (4) is
It is made of Al and has a flat plate surface on which alumite treatment is applied, and is connected to a reaction gas supply pipe (5) for introducing a reaction gas from a gas supply source (not shown) such as argon or freon. Further, a large number of small holes (not shown) are provided on the lower surface of the upper electrode (4), and the vacuum container (1) is opened from these small holes.
The reaction gas can be discharged into the inside. Moreover, the upper electrode (4) is for plasma generation, for example, power is 500W and 13MHz.
It is connected to a high-frequency power source (6) of the order of magnitude, and on the upper side of the upper electrode (4) from a cooling liquid circulator (not shown) so that the upper electrode (4) can be cooled with a circulating cooling liquid such as water. A disc-shaped upper electrode cooling block (8) capable of circulating a cooling liquid through a cooling liquid pipe (7) is provided.

Then, in the lower part of the vacuum container (1), a cooling liquid circulator (not shown) and a cooling liquid pipe (9) are provided like the upper electrode (4).
A disc-shaped lower electrode cooling block (10) that can circulate a cooling liquid, such as water, is provided through the surface of the lower electrode cooling block (10). A flat plate-shaped lower electrode (11) is installed, and this lower electrode (11) is grounded.

Here, the vacuum container (1) can be opened / closed by an opening / closing mechanism (not shown) such as a gate valve mechanism, and an object to be processed such as a semiconductor substrate (12) is transferred inside by a transfer mechanism (not shown) such as a hand arm. A semiconductor substrate (12) can be placed on the electrode (11). Moreover, the vacuum container (1) is in an airtight state when the opening / closing mechanism (not shown) is closed, and the inside of the vacuum container (1) can be brought to a desired vacuum state, for example, about several 10 mTorr to several tens Torr by a vacuum pump (not shown). Here, if a transfer mechanism (not shown) is installed in the vacuum spare chamber and airtightly connected to the vacuum container (1), the inside of the vacuum container (1) is transferred to a desired vacuum by a vacuum pump (not shown) after the semiconductor substrate (12) is transferred. The time to take can be shortened.

Then, on the outer periphery of the upper side of the lower electrode (11), there is provided a clamp ring (13) made of Al which is capable of crimping the outer peripheral portion of the mounted semiconductor substrate (12) to the lower electrode (11) and whose surface has been anodized. Ring lifting mechanism (15) via connecting rod (14)
For example, the clamp ring (13), the connecting rod (14), and the ring lifting mechanism (15) are installed so as to be able to move up and down by an air cylinder or the like, and the object to be processed, such as the semiconductor substrate (12), is connected to the upper electrode (4) and the lower electrode. It is a member of a clamp mechanism (16) that holds between the electrodes of (11) facing each other.

As shown in FIG. 2, the clamp mechanism (16) is made of Al, the surface of which is alumite treated, and the surface of which is coated with insulating alumina by the alumite treatment. Connecting rod (14) in which the surface of the rod (17) is covered with an insulating tetrafluoroethylene resin tube (18)
Are connected with SUS screws (19). The screw (19) is also covered with an insulating member (20 to 22) made of an insulating tetrafluoroethylene resin, and a conductive member such as Al or SU.
All the metals such as S are coated with insulation.

In addition, inside the vicinity of the center of the lower electrode (11), the semiconductor substrate (12) can be moved up and down with respect to the lower electrode (11) through a connecting portion (23), such as a pin lifting mechanism (24) such as an air. For example, 3 SUS lift pins (2
5) is provided. The lift pin (25), the connecting portion (23), and the pin lifting mechanism (24) are constructed as shown in FIG. That is, a lift pin (25) is screwed by a SUS spring (28) provided below the lower electrode (11) with a polyimide resin screw (26) via an insulating member (27) made of ethylene tetrafluoride resin. The SUS flat plate (29) provided can reliably transmit the lifting motion of the pin lifting mechanism (24) through the SUS rod (30) and the U-shaped tetrafluoroethylene resin insulating member (31). However, the lift pins (25), the springs (28), and the conductive members made of metal such as the rod (30) are in a floating state where they are not electrically connected to each other.

The lift pin (25) is inserted in the lower electrode (11) by utilizing a part of the hole (32) formed in the lower electrode (11). Further, the hole (32) is provided with a cooling gas supply pipe (33) so that a cooling gas from a cooling gas supply source (not shown), for example, helium gas can be supplied to the back surface of the semiconductor substrate (12).
It is connected to the.

Here, the semiconductor substrate (12) mounting surface of the lower electrode (11) is
The semiconductor substrate (12) is formed in a convex shape so as to have a deformation curve of the semiconductor substrate (12) when it is assumed that the force applied by the clamp ring (13) is applied to the semiconductor substrate (12) as a uniformly distributed load. There is.

Further, between the lower electrode (11) and the semiconductor substrate (12) mounting surface, the impedance between the semiconductor substrate (12) and the electrode holding the semiconductor substrate (12), that is, the lower electrode (11) is made uniform. As such, synthetic polymer film (34), for example, 20 μm thick
A heat-resistant polyimide resin having a thickness of about 100 μm is provided by adhering it to the semiconductor substrate (12) mounting surface of the lower electrode (11) with a heat-resistant acrylic resin adhesive.

And, between the outer circumference of the lower electrode (11) and the vacuum container (1),
An exhaust ring (37) made of an insulating material such as tetrafluoroethylene resin and having a large number of exhaust holes (36) is provided so that the reaction gas is exhausted to the exhaust pipe (35) on the side wall of the vacuum container (1).

Here, a shield ring made of an insulating material such as tetrafluoroethylene resin is provided on the outer periphery of the upper electrode (4) so that plasma can be generated in substantially the same size as the semiconductor substrate (12) held by the lower electrode (11). (38) is provided. Further, the etching unit having the above-mentioned configuration is controlled in operation and setting by a control unit (not shown).

Next, the semiconductor substrate (12) by the above-mentioned etching apparatus
The etching method will be described.

First, the vacuum container (1) is opened by an opening / closing mechanism (not shown), and the semiconductor substrate (12) transferred by a transfer mechanism (not shown) is placed on the lift pins (25) raised by the pin elevating mechanism (24) and the connecting portion (23). receive. After that, the lift pins (25) are lowered to place the semiconductor substrate (12) on the lower electrode (11),
The clamp ring (13) that had been raised by the ring lifting mechanism (15) and the connecting rod (14) is lowered, and the semiconductor substrate (12).
Is crimped to the lower electrode (11).

At this time, the opening / closing mechanism (not shown) of the vacuum container (1) is already closed, and the inside of the vacuum container (1) is in a desired vacuum state by a vacuum pump (not shown).

Then, the electrode elevating mechanism (2) and the connecting rod (3) lower the upper electrode (4) and set the electrode interval with the lower electrode (11) to a desired interval, for example, about several mm.

Next, a reaction gas such as argon is supplied from a gas supply source (not shown) to the upper electrode (4) through a gas supply pipe (5), and the reaction gas is supplied from a small hole (not shown) on the lower surface of the upper electrode (4) to a vacuum container. (1) It flows into the inside. At the same time, a harmonic voltage is applied to the upper electrode (4) by the high frequency power source (6) to generate plasma between the lower electrode (11) and the semiconductor substrate (on the lower electrode (11). 1
2) is etched.

At this time, the semiconductor substrate (12) is pressure-bonded to the lower electrode (11) by the clamp ring (13). However, in terms of microscopic surface roughness, etc., as shown in FIG. There is a gap (40) between the semiconductor substrate (12) and the semiconductor substrate (12). The impedance between the semiconductor substrate (12) and the lower electrode (11) due to the void (40) is small, but the uniformity is poor and the variation is large. Moreover, since the insulating layer of alumite on the surface of the lower electrode (11) is porous, the impedance uniformity between the semiconductor substrate (12) and the lower electrode (11) becomes worse. However, as shown in FIG. 4, as a means for making the impedance between the semiconductor substrate (12) and the electrode holding the semiconductor substrate (12), that is, the lower electrode (11) uniform, the semiconductor substrate (12) and the lower electrode ( 11) Between synthetic polymer films (34)
A heat-resistant polyimide resin having a thickness of about 20 μm to 100 μm was adhered to the lower electrode (11) with a heat-resistant acrylic resin adhesive having a thickness of about 25 μm. This void (40)
Since the impedance of the synthetic polymer film (34) between the lower electrode (11) and the lower electrode (11) is sufficiently larger than the impedance of the void (40), it is possible to reduce the impedance variation between the semiconductor substrate (12) and the lower electrode (11). , This impedance can be made uniform and uniform. Further, since the synthetic polymer film (34) is not porous like alumite, it has good contact with the semiconductor substrate (12) and has a void (4
The variation of 0) can be reduced, and the uniformity of the impedance of the void (40) can be improved. As a result, the impedance between the semiconductor substrate (12) and the lower electrode (11) becomes uniform, and as a result, the semiconductor substrate (12)
It is possible to improve the uniformity of etching. Here, the vacuum degree is 2.4 Torr, the high frequency power supply (6) output is 500 W, the Freon gas flow rate is 80 cc / min, and the argon gas flow rate is 500 cc / min.
When the temperature of the upper electrode (4) is 20 ° C and the temperature of the lower electrode (11) is 8 ° C or less, the lower electrode (11) having an insulating film thickness of 15 μm of alumite
A synthetic polymer film obtained by bonding a heat-resistant polyimide resin, which is a synthetic polymer film (34) with a thickness of 25 μm, onto a heat-resistant acrylic resin adhesive with a thickness of 25 μm (3
4) Set the number of sheets, etching rate, and etching uniformity to 5th.
Shown in the figure. From FIG. 5, it is clear that the etching rate is within a practical range and the etching uniformity is remarkably improved. Also, synthetic polymer films (34)
Since the material has a dense and stable surface, it is possible to prevent abnormal discharge due to variations in the impedance of the void (40), etc., and to perform stable etching processing without damaging the semiconductor substrate (12) due to abnormal discharge.

Here, at the time of the etching process, a cooling liquid by a cooling liquid circulator (not shown) passes through the cooling pipes (7, 9), the upper electrode cooling block (8) and the lower electrode cooling block (10),
When the upper electrode (4) and the lower electrode (11) are cooled to a desired temperature, the etching rate is improved. Further, a cooling gas from a cooling gas supply source (not shown) is passed through the cooling gas supply pipe (33) and the hole (32) between the semiconductor substrate (12) and the synthetic polymer film (34) at a predetermined pressure and flow rate, for example. Several cc / min
The temperature uniformity of the semiconductor substrate (12) is improved by supplying it in a certain degree and cooling the back surface of the semiconductor substrate (12), and as a result, the uniformity of etching is improved.

In addition, the insulating shield ring (38) provided on the outer peripheral portion of the upper electrode (4) and the insulating clamp ring (13) provided on the outer peripheral portion of the lower electrode (11) allow the surface of the semiconductor substrate (12) to be treated. Since plasma can be generated to have substantially the same size, plasma diffusion can be prevented and stable etching processing can be performed.

Then, the treated reaction gas is discharged from the exhaust pipe (35) through the exhaust hole (36) of the exhaust ring (37).

Here, the ions and charges in the plasmatized gas are drawn into the conductive member such as the surrounding metal so as to be attracted, and the plasmatized gas is easily diffused, but the periphery of the upper electrode (4) and the lower electrode (11) is likely to be diffused. 2 is a rod (17) which is a conductive member of a clamp mechanism (16) for holding a semiconductor substrate (12) between an upper electrode (4) and a lower electrode (11) as shown in FIG. ) Or screw (19) is coated with a cylinder (18) of tetrafluoroethylene resin, an insulating member (20 to 22) or alumina, and the insulating coating is applied to the upper electrode (4) to which a high frequency voltage is applied. The lower electrode (11) becomes the closest grounding part, and the plasmatized gas can be prevented from diffusing between the opposed upper electrode (4) and the lower electrode (11), and the plasmatized gas can be concentrated, so that etching can be performed. You can improve speed and uniformity, The etching process can be performed.

In addition, when the conductive member of the clamp mechanism (16) that is close to and in contact with the semiconductor substrate (12) is insulation-coated, it is possible to prevent charges from being accumulated in the conductive member and discharging to the semiconductor substrate (12). It is possible to prevent discharge breakdown of the semiconductor substrate (12).

Then, as shown in FIG. 3, lift pins (25), springs (28), flat plates (29) and rods (30) which are conductive members of a mechanism for moving the semiconductor substrate (12) up and down with respect to the lower electrode (11). Are connected by screws (26) made of insulating polyimide resin and insulating members (27, 31) made of ethylene tetrafluoride resin, so the electric capacity of the conductive member can be reduced, which allows plasma conversion. It is possible to prevent the gas from flowing around, and to prevent discharge breakdown of the semiconductor substrate (12) due to charge accumulation in the conductive member.

Moreover, the exhaust ring (37) for exhausting the reaction gas after processing
Since it is an insulating tetrafluoroethylene resin, ions and charges in the gas turned into plasma during exhaust flow,
It is possible to prevent the plasma from diffusing and concentrate the plasma between the upper electrode (4) and the lower electrode (11).

Next, the vacuum container (1) is opened by an opening / closing mechanism (not shown), the clamp ring (13) and the lift pin (25) are raised, and the semiconductor substrate (12) on the lift pin (25) is transferred by a transfer mechanism (not shown). The operation ends.

In the above embodiment, the conductive member for insulating coating is described as the member of the clamp mechanism that holds the object to be processed between the electrodes, but it is not limited to the above embodiment as long as it is a conductive member around the electrodes. .

Further, in the above-mentioned embodiment, the explanation has been made by using the coating of tetrafluoroethylene resin or alumina as the insulating coating means, but any method may be used as long as the conductive member around the electrodes can be coated with insulation, and the polyimide resin may be used. It goes without saying that the present invention is not limited to the examples.

As described above, according to this embodiment, the object to be processed is held between the opposed electrodes provided in the vacuum container, and a voltage is applied to the opposed electrodes to generate a plasma gas, In order to concentrate the plasma-enhanced gas between the electrodes, a means for insulating and coating the conductive member around the electrodes is provided, and the object to be processed is concentrated between the electrodes and etched with the plasma-enhanced gas. It is possible to prevent the ions and charges from flowing into the conductive member around the electrodes and diffusing the gas turned into plasma.

〔The invention's effect〕

As described above, according to the present invention, since the clamp ring that may be exposed to the plasma that processes the object to be processed is formed of metal, when the object to be processed is pressed against the mounting table,
The clamp ring can have sufficient rigidity. Further, since the surface of the metal clamp ring is covered with the insulating member, it is possible to prevent the gas that has been turned into plasma from flowing around and to prevent the discharge breakdown of the object to be processed due to the plasma.

[Brief description of drawings]

FIG. 1 is a configuration diagram for explaining the etching apparatus of the present invention, FIG. 2 is a diagram for explaining the clamp mechanism of FIG. 1, and FIG.
1 is a view for explaining the mechanism for moving the object to be processed up and down with respect to the lower electrode in FIG. 1, FIG. 4 is a view for explaining the function of the synthetic polymer film in FIG. 1, and FIG. It is a figure which shows the relationship between the etching rate of a figure, uniformity, and the number of synthetic polymer films. In the figure, 1 ... vacuum container, 4 ... upper electrode 11 ... lower electrode, 12 ... semiconductor substrate 16 ... clamping mechanism

Claims (3)

[Claims] 1. A voltage is applied between a mounting table provided in a vacuum container for mounting an object to be processed, and an electrode provided on the mounting table and an electrode arranged to face each other with the object to be processed provided therebetween. An electrode for generating plasma by applying a pressure, a clamp ring for holding the object to be processed by pressing the outer peripheral portion of the object to the mounting table, and a ring elevating mechanism for elevating the clamp ring, The etching device is characterized in that the clamp ring is made of metal, and the metal is covered with an insulating member. 2. The etching apparatus according to claim 1, wherein the clamp ring is made of aluminum and has a surface coated with an insulating alumina. 3. A means for insulatingly coating a conductive member is provided on a mounting surface of an electrode provided on a mounting table on which the object to be processed is mounted. Etching equipment.