JP3521454B2 - Plasma processing equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus for etching or depositing a film formed on the surface of a semiconductor wafer or the like.

[0002]

2. Description of the Related Art A plasma processing apparatus used for etching a surface of an object to be processed such as a semiconductor wafer is disclosed in JP-A-63-63
What is disclosed in Japanese Patent Publication No. 260030 is known. As shown in FIG. 11, this plasma processing apparatus has an opening 101 formed in a base 100, a stage / lower electrode 102 on which a workpiece W is placed is exposed from below, and the opening 101 is covered. Like base 100
A quartz chamber 103 is fixedly provided on the upper side, a cylindrical upper electrode 104 connected to a high frequency power source is provided on the upper part of the quartz chamber 103 having a small diameter, and an exhaust ring 105 is attached to the inner peripheral portion of the opening 101. The upper surface of the exhaust ring 105 is covered with an insulating ring 106 made of quartz.

[0003]

The exhaust ring 105 of the plasma processing apparatus described above is made of metal such as aluminum alloy, and the lower electrode 102 is also made of metal. Therefore, the plasma generated in the chamber 103 tends to fly toward the exhaust hole between the lower electrode 102 and the exhaust ring 105 while avoiding the object W to be processed, and abnormal discharge tends to occur there.

Although the upper surface of the exhaust ring 105 is covered with the insulating ring 106, since it is inside the quartz chamber, a slight gap is created between the exhaust ring 105 and the quartz chamber 103. Abnormal discharge is likely to occur. When the above-mentioned abnormal discharge occurs, not only stable discharge cannot be obtained, but also the workpiece W is damaged and the yield is reduced.

[0005]

SUMMARY OF to the first aspect of the present invention to solve the above problems, as well as providing the exhaust ring around the and the lower electrode in a chamber of a plasma processing apparatus, prior to
Note that the upper surface of the exhaust ring should touch the inner surface of the chamber.
An insulating ring is provided, and a ring-shaped ground electrode is further provided on the outer periphery of the lower portion of the chamber.

In the second invention of the present application, an exhaust ring is provided around the lower electrode of the plasma processing apparatus, the exhaust ring is extended radially outward, and the chamber is attached to the extended portion.

Further, in the third invention of the present application, an insulating ring is provided on the upper surface of the lower electrode of the plasma processing apparatus and at the portion where the peripheral edge of the object to be processed is applied.

[0008]

According to the first aspect of the invention, the generated plasma flies to the ring-shaped ground electrode before it flies to the exhaust hole or the gap between the exhaust ring and the chamber. Further, according to the second invention, the gap between the exhaust ring and the chamber is eliminated, and abnormal discharge is less likely to occur. Further, according to the third invention, the sputtering phenomenon at the peripheral portion of the workpiece W is eliminated, and The processed shape in the peripheral portion of the object W is improved.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 is a cross-sectional view of a plasma processing apparatus according to the present invention. The plasma processing apparatus has an opening 2 formed in a base 1 made of an aluminum alloy, and the processing target W such as a semiconductor wafer is formed in the opening 2 from below. The grounded lower electrode 3 which also serves as a stage for mounting is exposed.

An exhaust ring 4 made of aluminum alloy is attached to the inner peripheral portion of the opening 2. The exhaust ring 4 includes a tubular portion and a flange portion that extends radially outward.
An exhaust hole 5 is formed in the flange portion, and a quartz chamber 6 is installed in the flange portion. By thus extending the flange portion of the exhaust ring 4 and installing the quartz chamber 6 on the flange portion, the conventional gap formed between the outer end surface of the exhaust ring and the inner end surface of the quartz chamber is eliminated, resulting in abnormalities. Discharge is less likely to occur.

The quartz chamber 6 has a substantially bell jar shape, and the upper half portion has a small diameter portion, and a cylindrical upper electrode 7 connected to a high frequency power source is provided on the outer periphery of the small diameter portion. The upper electrode 7 may be formed in a half shape, and one electrode may be connected to the high frequency power source and the other electrode may be connected to the ground.

Further, an insulating ring 8 made of quartz whose outer peripheral end is in contact with the inner peripheral surface of the quartz chamber 6 is attached to the upper surface of the exhaust ring 4 to prevent abnormal discharge from occurring on the upper surface of the exhaust ring 4. There is.

Further, a ring-shaped ground electrode 9 is provided on the outer peripheral surface of the lower portion of the quartz chamber 6. With such a configuration, the plasma is blown to the ground electrode 9 before it is blown to the exhaust hole or the like, so that abnormal discharge is prevented.

On the other hand, the object W to be processed is placed on the upper surface of the lower electrode 3.
The insulating ring 10 made of quartz is also provided at the portion where the peripheral edge of the above is applied. As a result, the sputtering phenomenon can be prevented, the deposition on the object W to be processed is eliminated, the variation in the processed shape at the central portion and the peripheral portion of the object W to be processed is eliminated, and uniform processing can be performed.

In the illustrated example, a downstream type plasma processing apparatus having a cylindrical upper electrode provided outside the upper portion of the chamber is shown. However, a parallel plate having a flat electrode parallel to the lower electrode in the chamber is shown. Type plasma processing apparatus may be used.

In the above, after decompressing the inside of the chamber 6, a predetermined reaction gas is introduced into the chamber and a high frequency is applied to the upper electrode 7, so that the upper electrode 7 and the lower electrode 3 installed in the upper portion of the chamber 6 A stable electric discharge is obtained between and, and the surface of the workpiece W is etched.

Next, a concrete example of the formation of a multilayer circuit using the above-described plasma processing apparatus in an etching process is shown in FIG.
The process order will be described with reference to FIGS. First, as shown in FIG. 2, a conductor pattern 12 constituting a first-layer circuit such as an Al wiring is formed on an insulating film (interlayer insulating film) 11 formed on the surface of an object W by plasma CVD or the like. Further, an insulating protection film 13 such as Si ₃ N ₄ is formed on the conductor pattern 12 by plasma CVD.

[0018] Since the insulating protective film 13 is corrosion and deterioration and directly contacting the planarizing film to be described later a conductor pattern 12 occurs, which is formed in order to prevent this, Si ₃ N
Other than ₄ , SiO ₂ or the like may be used.

Next, the insulating protective film 13 is formed by using the above-mentioned downstream etching apparatus (plasma processing apparatus).
Are etched as shown in FIG. The etching conditions are an Ar atmosphere of 0.1 Torr and a high frequency power of 0.8 to 1.4 kW. Then, the insulating protective film 1 is formed by the above etching.
3 edges were removed, while the removed Si ₃ N
The shape of the insulating protection film 13 at the portion where _{4 and the} like are attached to the recess and covers the conductor pattern 12 is substantially trapezoidal. That is, the angle θ of the rising portion of the insulating protective film 13 becomes 90 ° or more, and the stress acting on this portion is relieved.

Thereafter, as shown in FIG. 4, the insulating protective film 13 is formed.
A coating liquid for forming a flattening film is applied onto the above by spin coating, and this is dried and solidified to form a flattening film 14. As the flattening film 14, a polyimide film or an SOG film such as Si (OCH ₃ ) ₄ is generally used.

As described above, if the side wall portion of the insulating protective film 13 is deposited to have a substantially trapezoidal shape, the above-mentioned θ becomes 90 ° or more, so that even if the pattern interval becomes narrow, it is ensured in the meantime. The coating liquid for forming the flattening film can be filled, and the flattening degree can be increased.

Then, as shown in FIG. 5, etching back is performed. Etch back is performed until the insulating protective film 13 is exposed. If the insulating protection film 13 is exposed as described above, if the state of FIG. 4 is left as it is, a contact hole is formed through the flattening film 14, and the inner surface of the contact hole is formed by CVD. A conductor is deposited by the above method, but gas is generated when a contact hole is formed in the flattening film 14, and C is generated when this gas is generated.
The conductor cannot be deposited by VD or the like.
Therefore, as shown in FIG. 5, etching back is performed until the insulating protective film 13 is exposed, and a contact hole is formed in this portion.

Then, as shown in FIG. 6, an interlayer insulating film 15 is formed on the flattened film 14 which has been etched back by CVD or the like, and as shown in FIG. 7, a resist mask 16 is formed.
Is used as a mask to form holes 17 in the insulating protective film 13 and the interlayer insulating film 15 whose sidewalls are substantially vertical.

After removing the resist mask 16 by ashing, the hole 17 is etched to widen the upper end of the hole 17, as shown in FIG. When the upper end is widened by etching, the part cut by etching is hole 1
7 adheres to the bottom portion, and the diameter of the bottom portion is reduced, resulting in an insufficient contact hole. Therefore, wet etching is performed with dilute hydrofluoric acid or the like, and the bottom of the narrowed hole 17 is returned to its original size as shown in FIG. I have to.

When the contact hole is formed in this manner, the conductor pattern 18 of the second layer circuit is formed on the interlayer insulating film 15 as shown in FIG. 1st layer conductor pattern
2 and the conductor pattern 18 of the second layer are electrically connected.

[0026]

As described above, according to the first invention of the present application, by providing the ring-shaped ground electrode on the outer periphery of the lower portion of the chamber, the plasma first jumps to the ring-shaped ground electrode. It is possible to prevent a sudden abnormal discharge that has occurred between the exhaust ring and the chamber. Further, in the second invention of the present application, since the exhaust ring is extended outward in the radial direction and the chamber is attached to this extended portion, there is no gap between the exhaust ring and the chamber, and abnormal discharge can be prevented. Further, in the third invention of the present application, since the insulating ring is provided on the upper surface of the lower electrode and at the portion where the peripheral edge of the set workpiece is applied, sputtering at the peripheral edge of the workpiece can be prevented, and the workpiece can be prevented. Can be processed uniformly. Furthermore, if the structure of the embodiment incorporating all the structures of the first invention to the third invention is adopted, the effect of preventing abnormal discharge is further enhanced and damage is reduced.

Further, since abnormal discharge can be prevented, it has become possible to apply a high frequency power of 0.8 kW or less in the prior art, but now it is possible to apply a high frequency of 1.7 kW. In addition, the in-plane uniform treatment of the object to be treated can be achieved.

[Brief description of drawings]

FIG. 1 is a sectional view of a plasma processing apparatus according to the present invention.

FIG. 2 is a diagram showing a state in which an insulating protective film is formed on an Al wiring.

FIG. 3 is a diagram showing a state in which the insulating protective film of FIG. 2 is etched.

FIG. 4 is a diagram showing a state in which a planarizing film is formed on the insulating protective film of FIG.

5 is a diagram showing a state in which the flattening film of FIG. 4 is etched.

6 is a diagram showing a state in which an interlayer insulating film is formed on the planarizing film of FIG.

FIG. 7 is a diagram showing a state in which a vertical hole to be a contact hole is formed.

8 is a diagram showing a state in which the vertical holes in FIG. 7 are etched.

9 is a view showing a state where the vertical holes of FIG. 8 are wet-etched with an acid.

FIG. 10 is a diagram showing a state in which a second layer circuit is formed on an interlayer insulating film.

FIG. 11 is a sectional view of a conventional plasma processing apparatus.

[Description of Reference Signs] 1 ... Base, 2 ... Opening, 3 ... Lower electrode, 4 ... Exhaust ring, 6 ... Quartz chamber, 7 ... Upper electrode, 8, 10 ... Insulating ring, 9 ... Ring-shaped ground electrode, 11 ... Insulation film,
12, 18 ... Conductor pattern, 13 ... Insulating protective film, 14 ...
Flattening film, 15 ... Interlayer insulating film, 17 ... Contact hole, W ... Object to be processed.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Naomi Nagatsuka               150 Nakamaruko, Nakahara-ku, Kawasaki City, Kanagawa Prefecture               Within Tokyo Ohka Kogyo Co., Ltd. (72) Inventor Susumu Okano               150 Nakamaruko, Nakahara-ku, Kawasaki City, Kanagawa Prefecture               Within Tokyo Ohka Kogyo Co., Ltd.                (56) References Japanese Patent Laid-Open No. 61-54630 (JP, A)                 JP-A-63-211629 (JP, A)                 JP-A 1-251735 (JP, A)                 JP-A-2-258048 (JP, A)                 JP 63-73624 (JP, A)

Claims (3)

(57) [Claims] 1. A plasma processing apparatus in which a lower electrode also serving as a stage of an object to be processed is faced below the chamber, and an upper electrode is provided inside or outside the upper portion of the chamber, the periphery of the lower electrode in the chamber. An exhaust ring is provided on the exhaust ring, and
An insulating ring that is in contact with the inner surface of the chamber is provided.
In addition , the plasma processing apparatus is characterized in that a ring-shaped ground electrode is further provided on the outer periphery of the lower portion of the chamber. 2. A plasma processing apparatus in which a lower electrode also serving as a stage of an object to be processed is faced below the chamber, and an upper electrode is provided inside or outside the upper portion of the chamber, an exhaust gas is provided around the lower electrode. The plasma processing apparatus according to claim 1, wherein a ring is provided, the exhaust ring is extended radially outward, and the chamber is attached to the extended portion. 3. A plasma processing apparatus in which a lower electrode also serving as a stage of an object to be processed is exposed below the chamber, and an upper electrode is provided inside or outside the upper part of the chamber, the upper surface of the lower electrode being processed. claims, characterized in that a insulating ring to the periphery takes part of the object
The plasma processing apparatus of 1 or 2 .