JP3357737B2 - Discharge plasma processing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention
The present invention relates to a discharge plasma processing apparatus that performs processing such as etching, ashing, or plasma CVD on semiconductors, electronic components, and other substrates.

[0002]

2. Description of the Related Art A so-called inductively coupled discharge system, in which high-frequency power is introduced through a dielectric partition for plasma generation, has conventionally been used for etching, plasma CVD and the like. FIG. 3 of the accompanying drawings shows an example of an inductively coupled discharge type etching apparatus. A is a vacuum chamber, in which a substrate electrode C for mounting a substrate B is arranged. It is connected to the. At a position facing the substrate electrode C, a counter electrode E is mounted via a dielectric partition F. An RF coil G is provided around the dielectric partition F. In the conventional inductively coupled discharge type etching apparatus as shown in FIG. 3, when the substrate is small, uniformity of the processing speed has not been a serious problem. However, recently, the use of 8-inch wafers has led to a problem of processing uniformity in the inductive coupling method. In the etching by the inductive coupling method, the diffusion of the plasma generated by the inductive coupling in the direction of the substrate is used. If the distance between the plasma generating unit and the substrate is longer than the distance between the substrate and the side wall of the vacuum chamber, uniform plasma is generated. Even in the diffusion process, plasma loss due to diffusion to the chamber side wall increases, and plasma uniformity on the substrate surface cannot be obtained. In order to avoid this, it has been proposed to move the plasma generation unit closer to the substrate. However, another problem arises that the transport mechanism for replacing the substrate becomes complicated and causes a reduction in the reliability of the apparatus. . It has also been proposed to improve the uniformity by increasing the high-frequency bias power applied to the substrate electrode higher than the high-frequency power for plasma generation, but this method cannot take advantage of the inductive coupling. .

[0003]

In order to achieve a large area and high uniform etching using inductively coupled plasma,
High uniformity of the plasma on the substrate surface is required.
However, even if highly uniform plasma is formed, a large amount of plasma is lost to the side wall during the diffusion process, so that a uniform plasma distribution is not obtained on the substrate surface. Various methods have been proposed to make this uniform, but there have been problems such as not taking full advantage of the inductive coupling method, complicating the substrate transfer system, and lowering the reliability of the entire apparatus. Accordingly, an object of the present invention is to solve the problems of the conventional processing apparatus using inductively coupled plasma and to provide a highly reliable processing apparatus capable of performing highly uniform processing.

[0004]

According to the present invention, there is provided, in accordance with the present invention, an antenna for generating plasma by introducing high-frequency power into a vacuum chamber through a dielectric partition, and In a discharge plasma processing apparatus equipped with a mechanism capable of applying a high-frequency bias for processing and using a plasma in a vacuum chamber to process the object, a high-frequency power application electrode on which the object is placed is provided. The opposing electrode provided oppositely is formed in a convex shape toward the high-frequency power application electrode, and the distance between the high-frequency power application electrode and the counter electrode is defined by the radius of the object to be treated and the radius of the convexly configured opposing electrode. It is characterized by being set based on the relationship. Preferably, the counter electrode may include a columnar protrusion extending toward the high-frequency power application electrode or a protrusion having a semi-elliptical cross section. When the opposite electrode has a columnar projection, the distance between the tip of the projection and the high-frequency power application electrode is substantially equal to the difference between the radius of the object to be processed and the radius of the opposite electrode having the projection. When the counter electrode is provided with a columnar protrusion extending toward the high-frequency power application electrode or a protrusion having a semi-elliptical cross section, the tip of the protrusion and the high-frequency power application electrode The distance of
It can be configured to be substantially equal to the difference between the radius of the object to be processed and half the radius of the base of the counter electrode having the protrusion.

[0005]

In the discharge plasma processing apparatus configured as described above, the distance between the high-frequency power application electrode, that is, the substrate electrode and the counter electrode is set based on the relationship between the radius of the object to be processed and the radius of the counter electrode. Since the loss to the wall surface during the plasma diffusion process is made substantially equal between the central portion and the outer peripheral portion, uniformity of the plasma density on the substrate surface can be obtained. The number of ions extracted by the high-frequency bias from the plasma that has become uniform on the substrate surface is uniform, and a process such as a highly uniform etching process or an ashing process can be performed.

[0006]

FIG. 1 schematically shows an example in which the present invention is implemented as an etching apparatus, wherein 1 is a vacuum chamber,
Reference numeral 2 denotes a substrate electrode arranged in the vacuum chamber 1, which is connected to a high-frequency power supply 3. A substrate 4 to be etched is mounted on the substrate electrode 2 as shown. The vacuum chamber 1 is connected to an exhaust system (not shown) via an exhaust port 1a. Reference numeral 5 denotes a counter electrode located opposite to the substrate electrode 2, and the counter electrode 5 is attached to a wall of the vacuum chamber 1 via a dielectric partition 6. Dielectric partition 6
An RF coil 7 is provided on the outer periphery of the antenna. The RF coil 7 constitutes an antenna for generating plasma by introducing high-frequency power into the vacuum chamber 1 through the dielectric partition 6. The counter electrode 5 has a columnar projection 5a extending toward the substrate electrode 2, and the distance between the tip of the projection 5a and the substrate 4
L1 is the radius r1 of the substrate 4 and the radius r2 of the columnar projection 5a.
Is set to be equal to the difference (r1 -r2).

A description will be given of an experimental example in which etching is performed using the illustrated apparatus configured as described above. As experimental conditions, 0.067 Pa of Ar gas was introduced into the vacuum chamber 1,
An inductively coupled high frequency power of 800 W (13.56 MHz) is applied to the RF coil 7, and a high frequency power of 600 W (13.56 MHz) is applied to the substrate electrode 2.
Was applied. The distance L1 between the tip of the protrusion 5a of the counter electrode 5 and the substrate 4 is set to 50 mm, and the radius r1 of the substrate 4 and the columnar protrusion are set.
The difference (r1-r2) from the radius r2 of the tip of 5a is also substantially equal
When the thickness was 50 mm, etching uniformity of ± 2% was obtained. At this time, the etching rate of the silicon thermal oxide film used for the substrate 4 was 65 nm / min. As a comparative example, one in which the columnar projection 5a was not provided on the counter electrode 5 in FIG. 1 (corresponding to the conventional example shown in FIG. 3) was prepared and an experiment was performed. As a result, the best uniformity was ± 8%. An experiment was conducted in which the conditions of good uniformity were obtained using the position of the antenna, that is, the RF coil, the ratio of the upper and lower high-frequency powers, and the pressure as parameters, but no uniformity of 8% or less was obtained. From this experimental example, it was recognized that the apparatus shown in FIG. 1 can greatly improve the uniformity as compared with the conventional inductively coupled etching apparatus.

FIG. 2 shows another example in which the present invention is implemented as an etching apparatus, and portions corresponding to FIG. 1 are denoted by the same reference numerals. In this embodiment, a protruding portion 8a having a semi-elliptical cross section is provided on the opposing electrode 8 located opposite the substrate electrode 2. In this case, too, the distance L1 Is set to be equal to the difference between the radius r1 of the substrate 4 and 1/2 of the radius r3 of the root of the projection 8a (r1 -1 / 2.r3). An experiment similar to that of FIG. 1 was performed using the apparatus having the structure shown in FIG. 2, and as a result, also in this case, the difference between the radius r1 of the substrate 4 and 1/2 of the radius r3 of the root of the projection 8a ( The best uniformity was obtained when (r1 -1 / 2.r3) was around 50 mm.

In the illustrated embodiment, a counter electrode having a columnar projection and a projection having a semi-elliptical cross section are used as counter electrodes located opposite to the substrate electrode. May be made convex so that the distance between the substrate electrode and the counter electrode is substantially equal to the difference between the radius of the substrate and the radius of the counter electrode.Therefore, its shape and dimensions can be arbitrarily and appropriately selected. . In the above embodiment, the case where the present invention is implemented as an etching apparatus has been described. However, the present invention can be similarly implemented in other processing apparatuses using discharge plasma, for example, an ashing apparatus and a CVD apparatus. The same effect as the example can be obtained.

[0010]

As described above, according to the present invention, the distance between the substrate electrode and the counter electrode, the difference between the radius of the substrate and the radius of the counter electrode, or the difference between the radius of the object to be processed and the base of the counter electrode. Since the counter electrode is configured to be convex toward the substrate electrode so that the difference from half the radius is substantially equal to each other,
The loss due to the diffusion of the generated plasma is equal at the central portion and the outer peripheral portion, and uniform plasma can be formed on the substrate surface. As a result, the number of ions extracted from the uniform plasma formed on the substrate surface by the high-frequency bias becomes uniform, so that highly uniform processing can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an etching apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view showing another embodiment of the present invention.

FIG. 3 is a schematic sectional view showing a conventional example of an inductive coupling type etching apparatus.

[Explanation of symbols]

 1: vacuum chamber 2: substrate electrode 3: high-frequency power supply 4: substrate 5: counter electrode 5a: cylindrical protrusion 6: dielectric partition 7: RF coil (antenna) 8: counter electrode 8a: protrusion having a semi-elliptical cross section

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Masahiro Ito 2500 Hagizono, Chigasaki-shi, Kanagawa Japan Vacuum Engineering Co., Ltd. (56) References JP-A-7-169703 (JP, A) JP-A-1-296600 (JP, A) JP-A-5-226324 (JP, A) JP-A-6-17253 (JP, A) JP-A-4-207027 (JP, A) Japanese Translation of PCT Application No. 8-508852 (JP, A) ( 58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/31 C23C 16/505 H01L 21/3065 H05H 1/46

Claims (6)

(57) [Claims] 1. An antenna for generating plasma by introducing high-frequency power into a vacuum chamber through a dielectric partition, a mechanism capable of applying a high-frequency bias for processing an object to be processed is provided, and the plasma is generated in the vacuum chamber. In a discharge plasma processing apparatus configured to process an object to be processed by using the same, a counter electrode provided to face the high-frequency power application electrode on which the object is mounted is formed in a convex shape facing the high-frequency power application electrode. And a distance between the high-frequency power application electrode and the counter electrode is set based on a relationship between a radius of the object to be processed and a radius of the convex counter electrode. 2. The discharge plasma processing apparatus according to claim 1, wherein the counter electrode has a columnar projection extending toward the high-frequency power application electrode. 3. The discharge according to claim 2, wherein the distance between the high-frequency power application electrode and the counter electrode is made equal to the difference between the radius of the object to be processed and the radius of the counter electrode formed in a convex shape. Plasma processing equipment. 4. The discharge plasma processing apparatus according to claim 1, wherein the counter electrode has a semi-elliptical projection extending toward the high-frequency power application electrode. 5. The distance between the high-frequency power application electrode and the counter electrode is made equal to the difference between the radius of the object to be processed and half of the radius of the base of the counter electrode formed in a convex shape. 3. The discharge plasma processing apparatus according to claim 1. 6. The discharge plasma processing apparatus according to claim 1, wherein the counter electrode is supported at one end of the dielectric partition.