JP2593690Y2 - LEP quartz chamber - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in the structure of a quartz chamber such as an etching apparatus utilizing LEP plasma, a thin film growth apparatus, and an ion implantation apparatus. The LEP device uses a rotating electric field to accelerate electrons and thereby excite gas to produce plasma. In order to generate a rotating electric field, three or more M upper electrodes are provided so as to be rotationally symmetrical inward with respect to each other. 360 / M on these electrodes
A high-frequency voltage having a phase different from each other is applied. Then, a rotating electric field is generated in a region surrounded by the electrodes. Since a rotating electric field is created by a combination of a plurality of electrodes, the name of Lissajous is taken and is abbreviated as LEP.

[0002]

2. Description of the Related Art An LEP device is first disclosed in Japanese Patent Application No. 2-40231.
9 and Japanese Patent Application No. 4-215820. It includes three or more upper electrodes, a lower electrode provided below them, a high-frequency power supply, a cooling mechanism for the electrodes, and the like.
The upper electrode and the lower electrode are provided inside the chamber. A substrate to be processed is placed on the lower electrode. The upper electrode is strongly heated because the plasma violently collides and discharges each other. The lower electrode is also heated because the plasma collides with strong momentum. There, the upper and lower electrodes are cooled.

For example, a chamber in which an insulating film is formed by spraying alumina inside a metal such as stainless steel is used. The chamber must be electrically insulated from the upper and lower electrodes. Imperfect insulation causes a discharge between the inner walls of the chamber and the electrodes. Then, a material in which alumina was sprayed on the inner surface of the metal chamber was used. Since the main body is a metal, it is easy to attach the electrodes and the cover plate. You can also elaborate the shape.

[0004]

However, it has been found that the sprayed alumina on the inner surface of the metal chamber has a disadvantage that particles are easily generated. A particle is a fine powder. The alumina on the chamber wall seems to be cut into fine powder by the excitation of the plasma. This scatters on the inner surface of the container and contaminates the container. The substrate is also contaminated by the particles. Even small particles are fatal in the production of highly integrated semiconductors.

[0005] It must be devised so as not to generate particles. The wall surface as-sprayed with alumina is a rough surface having many irregularities. If the surface is rough, some alumina may be in an unstable state. It is understandable that this is beaten by the plasma and shaved. Therefore, this was polished to make a smooth surface. However, it has been found that particles are generated even on a flat surface and contaminate the chamber and the substrate.

If the chamber is made of metal, it must be insulated from the upper and lower electrodes. If the chamber is made of quartz, there is no insulation problem. Since quartz has a hard surface, it will not generate particles when struck with plasma. However, it is difficult for the quartz chamber to support the upper electrode and the cooling structure of the upper electrode. This is because you cannot make holes or cut screws. Again, a metal chamber should be used to support the top electrode and the like.

[0007]

The chamber of the LEP device of the present invention is provided on a cylindrical metal outer chamber, a cylindrical quartz chamber inscribed in the metal outer chamber, and a metal outer chamber. A ceiling lid for holding the upper electrode, a base chamber provided below the metal chamber, and a heater provided on the outer periphery of the outer metal chamber for heating the inner quartz chamber. A seal was provided between the inner chambers so that both the outer metal chamber and the inner quartz chamber were kept airtight. Also, it is possible to form a viewing window simply by drilling a hole in the metal chamber.

[0008]

An etching gas (chlorine gas) is introduced from the outside, and a high-frequency voltage having a different phase is applied to the upper electrode and a high-frequency voltage is applied to the lower electrode. The gas is excited by the rotating electric field.
Plasma is generated. This etches the wafer 3. The plasma strikes the walls of the chamber, but directly hits the quartz surface. It has a hard surface and is not etched. Therefore, no particles are generated from the chamber.

Since the quartz is indirectly heated by the heater, there is no deposit on the inner surface of the quartz. The inner wall surface of quartz can be kept clean. The state of internal discharge and the state of etching can be observed through the viewing window. Since there is no cylindrical portion like a port, the opening angle is wide and the observable area is wide even if the peephole is relatively small.

[0010]

FIG. 1 is a schematic sectional view of an LEP chamber according to an embodiment of the present invention. A metal base chamber 1 is provided at the lowermost position. In the central recess, via an insulator 15,
The lower electrode 2 is provided. The wafer 3 is placed thereon. This wafer is etched. The wafer is, for example, a substrate in which a thin film of a semiconductor, an insulator, a metal, or the like is formed on a GaAs substrate, an InP substrate, or a Si substrate and an arbitrary resist pattern is drawn by photolithography.

Above the base chamber 1, a quartz chamber 4 having a cylindrical or rectangular tube shape is provided. It is surrounded by a metal chamber 5. The quartz chamber 4 is inscribed in the metal chamber 5. Airtightness is maintained between the quartz chamber 4 and the metal chamber 5. The metal chamber is an aluminum or stainless steel chamber.

The quartz chamber 4 is referred to herein as a quartz chamber to clarify that it is inside. The metal chamber 5 is sometimes called an external metal chamber to make it clear that it is outside. A sheath heater 6 is wound around the outer periphery of the outer metal chamber 5. This heats the quartz so that no deposits adhere to the inner surface of the quartz.

A ceiling lid 7 is attached to the upper opening of the metal outer chamber 5. The ceiling lid 7 has an opening, from which the upper electrode 8 is suspended. Here, there are three electrodes, but this may be four or five. For this, high-frequency electric fields having different phases are applied. An etching gas is introduced from the outside, and the gas is turned into plasma by a rotating electric field. High frequency is also applied to the lower electrode 2. The wafer 3 is etched by the plasma.

Importantly, the inner quartz chamber and the outer metal chamber are capable of maintaining a vacuum together. The vacuum is not maintained only by the metal outer chamber. The inner surface of the metal chamber and the outer surface of the quartz chamber are machined so as to be loosely fitted.

In order to maintain airtightness, O-rings 9 and 1 are provided between the outer peripheral surface of the quartz chamber and the inner peripheral surface of the outer metal chamber.
0 is interposed. One O-ring 9 is provided near the upper ends of both chambers, and the other O-ring 10 is provided near the lower ends of both chambers. The O-ring is inserted into a circumferential groove cut on the inner surface of the metal chamber 5. The upper and lower outer peripheries of the quartz chamber are tapered so that O-rings can easily enter. Of course, the groove for inserting the O-ring may be cut in the outer peripheral surface of the quartz chamber.

The space between the upper and lower O-rings is isolated from the inner space of the chamber. Even if a hole is formed in a portion sandwiched between the upper and lower O-rings 9 and 10 of the metal outer chamber, a vacuum can be maintained by the quartz chamber.
Therefore, a hole 11 is formed in the side wall of the metal chamber 5. This becomes the viewing window 11. Air enters between the quartz chamber and the metal chamber.

In the case of a normal metal chamber, an opening is formed in a metal side wall, a port of a metal cylinder is erected there, and a glass window is attached to the tip of the port. In the case of the present invention, it is only necessary to drill a hole in the metal wall. This is because there is transparent quartz behind the hole so that a vacuum can be maintained instead of a glass window. Moreover, there is no need to make a port simply by making a hole. The structure of the viewing window can be made extremely simple.

When a viewing window is attached, an air layer is formed outside the quartz and inside the metal. However, O-rings 9, 10
Therefore, the vacuum in the chamber is not impaired. If this is air, heat conduction will be better than if it is a vacuum. The heat of the external heater is easily transmitted to the quartz chamber, and the quartz can be efficiently heated.

If the sight glass is not formed in the metal chamber, the internal air layer may thermally expand and impair the degree of vacuum inside through the O-ring. In order to avoid this, it is necessary to make a vent hole. In order to heat the quartz chamber more efficiently by increasing heat conduction, a gas having a small molecular weight (such as helium) may be filled in a narrow space sandwiched between O-rings. Alternatively, a liquid such as water may be put between the O-rings.

An O-ring 12 is provided between the ceiling lid 7 and the outer metal chamber 5, and also has an airtight structure. O between the base chamber 1 and the metal outer chamber 5
There is a ring 13 and it is airtight.

An insulator 17 is provided on the inner surface of the ceiling lid 7.
This can be a quartz plate or a ceramic layer. The inner surface of the outer metal chamber is covered with quartz. The upper electrode 8 must be insulated from the chamber, but the insulator 17 in the ceiling lid and the quartz chamber 4 spatially insulate the upper electrode.

The heater 6 heats the quartz chamber 4 through the metal layer. If the surface of quartz is cold,
Adhering substance adheres. In order to prevent this, heating is performed by the heater 6. The heater temperature is below 200 ° C.
A sheet heater in which a nichrome wire is covered with an insulator is used.
The inner surface of the quartz is maintained at about 70C to 100C.

Since the quartz is inside, it seems convenient to also provide the heater inside the metal chamber. However, in this case, a current introduction terminal for the heater is required, and an expensive heater for vacuum needs to be used. The present invention does not need such.

[0024]

The quartz chamber is inscribed in the metal chamber instead of spraying alumina on the inner surface of the metal chamber. The one facing the upper electrode is quartz. It has a hard, smooth surface and is not easily etched. Therefore, no particles are generated. The wafer is not contaminated by particles. Since processing is performed in a clean atmosphere, the yield of semiconductor production can be increased.

Since there is a heater and the quartz is heated, there is no deposit on the inner surface of the quartz. There is no danger of the wafer being contaminated by the re-scattering of the deposit. Since this heater is provided outside, an expensive heater for vacuum need not be used. Inexpensive heaters for the atmosphere can be used and costs can be reduced. Since there is a heater outside, there is no need for a current introduction terminal for guiding current into the chamber. Wiring work space in the chamber can be reduced.

Quartz has a simple cylindrical or prismatic shape. Since the metal outer chamber circumscribes it, it has a simple shape. A normal metal chamber is opaque, so it is necessary to make a port and attach a glass window to it. In the present invention, the processing of the chamber is extremely simple, since the view window can be obtained by merely drilling a hole. Po
This is also simplified because there is no need to create a project.

It is metal that supports the load of the ceiling lid.
No vertical load is applied to the quartz chamber. Quartz need only be strong enough to withstand the internal pressure. Since the thickness of quartz can be reduced and processing can be facilitated, the cost of the quartz chamber can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an LEP quartz chamber according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base chamber 2 Lower electrode 3 Wafer 4 Quartz chamber 5 Chamber 6 Heater 7 Ceiling lid 8 Upper electrode 9 O-ring 10 O-ring 11 Viewing window 12 O-ring 13 O-ring 14 Insulator 15 Insulator

Claims (2)

(57) [Scope of request for utility model registration] 1. A cylindrical metal outer chamber, a cylindrical quartz inner chamber inscribed in the metal outer chamber, a ceiling lid provided on the metal outer chamber and holding an upper electrode, and a metal outer chamber. A seal member is provided between the outer metal chamber and the inner quartz chamber, including a base chamber provided below the chamber for holding a lower electrode, and a heater provided on the outer periphery of the outer metal chamber and heating the inner quartz chamber. A LEP quartz chamber characterized in that the airtightness is maintained by both the metal outer chamber and the quartz inner chamber. 2. A cylindrical metal outer chamber, a cylindrical quartz inner chamber inscribed in the metal outer chamber, a ceiling lid provided on the metal outer chamber and holding an upper electrode, and a metal outer chamber. A seal member is provided between the outer metal chamber and the inner quartz chamber, including a base chamber provided below the chamber for holding a lower electrode, and a heater provided on the outer periphery of the outer metal chamber and heating the inner quartz chamber. Pinch, keep the airtight by both the metal outer chamber and the quartz inner chamber,
A LEP quartz chamber characterized in that a hole is formed in a metal outer chamber to make it a view window.