JP2000077393A - Plasma processing equipment - Google Patents

Abstract

(57) [Summary] In a plasma processing apparatus, there has been a demand for uniforming all of an etching rate distribution, an etching shape, and a base film etching rate of an etching film on a substrate. In a plasma processing apparatus, a ring taller than a wafer is mounted on the outside of a substrate, and bias power is applied to the ring, so that reaction products accumulate in the ring and enter the substrate. The amount of the reaction product becomes uniform, and the productivity can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an etching apparatus or a CVD apparatus using plasma, and relates to a method for processing a sample such as a semiconductor element substrate by using a gas dissociated by plasma. The present invention relates to a plasma processing apparatus suitable for achieving a uniform processing speed distribution and a method for processing a substrate surface using the plasma processing apparatus.

[0002]

2. Description of the Related Art In a conventional plasma generating apparatus, for example, as described in Japanese Patent Application Laid-Open No. 2-11781, a focus ring is provided outside a substrate to make the velocity of gas on the substrate surface uniform. Thus, the substrate processing speed has been made uniform.

[0003]

In the etching of a semiconductor device, the uniformity of the etching rate distribution of the film to be etched, the underlying film and the resist, the anisotropy of the etching shape, and the high selection of the underlying film and the resist in the substrate. A ratio is required. The gas dissociates in the plasma, producing ions and several types of radicals (chemically active neutral molecules). Etching is caused by surface reactions of these ions with radicals and re-incident reaction products. Each film is treated by a different reaction due to ions, radicals, re-incident reaction products, and the like. Therefore, in order for the etching rate distribution of each film in the substrate to be uniform, it is required that the amounts of ions and various radicals incident on the substrate have a uniform distribution in the substrate.

[0004] The ions in the plasma are accelerated by a sheath electric field generated near the surface of the substrate, and vertically incident on the substrate. Therefore, if the plasma density and the sheath voltage are uniform on the substrate, the incidence of ions will be uniform on the substrate.

[0005] On the other hand, radicals are generated in plasma, but because they are neutral, they diffuse spatially and isotropically without being affected by the sheath electric field, are carried by the gas flow, and are different on the substrate and the wall of the chamber. It disappears or adheres with the reaction probability.

For this reason, radicals exhibit different density distributions in the chamber depending on the type. In an apparatus having an exhaust port on the outer peripheral side of the substrate, after the etching, the density distribution of the ejected reaction products on the substrate has an uneven distribution such that the density distribution is high at the center of the wafer and low at the outer circumference. As described above, even if the incidence of ions is uniform on the substrate, the incidence of various radicals and reaction products on the substrate has different non-uniform distributions, so that distribution control of these is necessary.

In the above prior art, the effect of accumulating the reaction product in the focus ring and making it uniform is sufficient.
There was no effect of lowering the concentration of high-concentration radicals generated in the plasma and formed on the upper part of the outer periphery of the substrate. for that reason,
It is not enough to prevent high-concentration radicals from entering the periphery of the substrate, and it has been difficult to simultaneously achieve uniformity in the etching rate distributions of the film to be etched, the underlayer, and the resist.

[0008]

In order to solve the above-mentioned problems, a ring that is taller than the substrate is arranged on the outer periphery of the substrate, and a bias power is applied to the ring to reduce the concentration of radicals generated near the outer periphery of the substrate. I tried to lower it.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will now be described with reference to FIGS.
This will be described with reference to FIGS. FIG. 1 is a sectional view of the etching apparatus. FIG. 2 is a sectional view taken along line AA of FIG. A substrate 4 rests on a second electrode 3 arranged opposite a first electrode 2 coupled to a chamber 1. A power supply 5a is connected to the first electrode 2, and a power supply 5b is connected to the second electrode 3. Plasma 7 is generated in the processing chamber 6 between the first electrode 2 and the second electrode 3 to process the substrate 4.

A central portion of the first electrode 2 has a large number of gas holes 2a.
Are open and connected to the gas supply means 8 to form a so-called shower head. Further, an exhaust port 9 is provided on the outer periphery of the second electrode 2. On the second electrode 3, on the substrate 4
The ring 10 is installed outside the. Ring 10
Is connected to a power supply 5c. An insulating plate 11 is inserted between the ring 10 and the second electrode 3. As the material of the ring 10, silicon or silicon carbide is used as a high-purity low-resistance material. Further, as the material of the first electrode, carbon, silicon, or the like is used.

As a plasma generating gas for etching, a mixed gas of argon and a fluorocarbon-based gas such as CF ₄ or C ₄ F _8, or Cl ₂ , BCL ₃ , SF ₆ , H
A gas such as Br is selectively used depending on a film to be etched.

For the above apparatus, for example, a mixed gas of argon and a fluorocarbon-based gas such as CF ₄ or C ₄ F ₈ is supplied from the gas supply means 8 to the gas hole 2 a of the first electrode 1 as a plasma generating gas. When supplied, the gas flows from this hole to the processing chamber 6 and is discharged from the exhaust port 9. Therefore,
When high-frequency power is applied to the electrodes 2 and 3 to generate the plasma 7, the gas is ionized and dissociated in the plasma to generate ions and radicals. Etched.

Radicals that contribute to etching include:
F, CF, CF ₂ , CF _{3 and the} like. Since the F radical generated in the plasma has a high reaction rate with Si,
When it is necessary to increase the selectivity of the first electrode, the material of the first electrode is made of silicon and a bias voltage is applied to the electrode in order to reduce the amount of F. Then, since F reacts with the electrode and is consumed, the concentration of F on the substrate decreases, but a region having a high concentration of F is formed on the outer peripheral side wall of the chamber because there is no silicon electrode.

On the other hand, CF radicals are not consumed by the silicon electrode, but etch the SiO ₂ film on the substrate. The F radical that has reacted with the resist releases a CF-based product into the chamber 6. Therefore, the concentration of CF radicals tends to increase at the center of the substrate.

On the other hand, reaction products generated from the film to be etched tend to collect at the center of the substrate. This product adheres to the side wall of the etching hole and becomes a part of the protective film, thereby affecting the etching shape.

The incident amounts of CF radicals, F radicals, and reaction products on the substrate are as shown in FIG. On the other hand, by installing the ring 10 outside the substrate, CF radicals and reaction products accumulate in the ring 10 and the amount of CF radicals and reaction products incident on the substrate is reduced on the substrate. Looks like When bias power is applied to the ring 10, F radicals formed outside the substrate are removed from the ring 10.
Therefore, the amount of F radicals that tend to be high at the outer periphery of the substrate becomes uniform. Due to the synergistic effect of this ring,
The amount of CF radicals, F radicals, and reaction products incident on the substrate becomes uniform within the substrate surface as shown in FIG.

The inside of the ring 10 has a curved shape as shown in FIG. By doing so, since the flow is formed smoothly without separation of the gas flow, the etching rate distribution on the substrate becomes uniform, and
There is an effect that a clean process can be achieved without stagnation of fine particles and the like.

As a result, the etching rate and the etching shape become uniform on the substrate, and there is an effect that high quality processing can be performed.

Further, by controlling the bias voltage applied to the ring 10 by changing the power of the power source 5c, there is an effect that uniform processing can be performed on various films to be etched.

The power supplies 5a, 5b and 5c are separate power supplies.
Power supplies having different frequencies may be used. Alternatively, a single power supply may be branched by a splitter (not shown) to supply power to each electrode. This configuration has the effect of saving power. Further, the ring 10 may be directly or indirectly mounted on the second electrode via a thin plate having electric resistance. This eliminates the need for the power supply 5c and has the effect of reducing the number of components.

FIG. 5 shows another embodiment of the present invention.
The amount of radicals in the plasma is monitored by 3 and the amount of change in the amount of radicals at the time of change to the etching of the multilayer film and the etching of the lower layer and the amount of radical change at the end of the etching are adopted. It controls so that the radical distribution on the substrate becomes uniform. With this configuration, there is an effect that the multilayer film can be etched while ensuring high etching rate uniformity.

FIG. 6 shows another embodiment of the present invention.
A plurality of grooves 10b are formed in the ring 10a. Such a groove may be a number of holes. Since such grooves and holes increase the surface area of the ring, there is an effect that a ring having a small size and a large amount of F radical reaction can be provided.

The above is an embodiment of the present invention applied to a parallel plate high frequency application type plasma apparatus. However, the present invention can be applied to an electron cyclotron resonance type plasma apparatus and an inductively coupled plasma apparatus. FIG. 7 shows an embodiment of the electron cyclotron resonance type plasma apparatus. An electromagnetic coil 15 is installed outside the chamber 1 to create a magnetic field condition in the processing chamber 6 where electron cyclotron resonance is generated. For example. When the electromagnetic wave is 2.45 GHz, 875 G is the electron cyclotron resonance condition. The electromagnetic wave introduced from the waveguide 16 propagates through the quartz window 2b into the processing chamber 6, and generates a plasma 7 by electron cyclotron resonance in the processing chamber. Also in this case, the same effect as described above can be obtained by installing the ring 10.

[0024]

According to the present invention, it is possible to obtain uniform performance in the substrate with respect to etching of a multilayer film with respect to the etching rate, the etching shape, and the selectivity, thereby improving the productivity.

[Brief description of the drawings]

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

FIG. 2 is a plan view of a first electrode of FIG. 1;

FIG. 3 is a distribution diagram of an incident amount on a substrate in the case of a conventional structure.

FIG. 4 is a distribution diagram of an incident amount on a substrate in the case of the present invention.

FIG. 5 is a sectional view of a plasma processing apparatus according to another embodiment of the present invention.

FIG. 6 is a sectional view of a plasma processing apparatus according to another embodiment of the present invention.

FIG. 7 is a cross-sectional view of a plasma processing apparatus according to another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Chamber, 2 ... 1st electrode, 3 ... 2nd electrode, 4 ... Substrate, 5a, 5b, 5c ... Power supply, 6 ... Processing chamber, 7 ... Plasma, 8 ... Gas supply means, 9 ... Exhaust port, 10 ... Ring, 1
DESCRIPTION OF SYMBOLS 1 ... Insulating plate, 12 ... Quartz window, 13 ... Light emission detector, 14 ...
Controller, 15: electromagnetic coil, 16: waveguide.

Continuation of the front page (72) Inventor Takahiro Tamai 3-2-2 Fujibashi, Ome-shi, Tokyo F-term in Hitachi Tokyo Electronics Co., Ltd. (Reference) 4K030 CA04 CA12 FA03 JA17 KA15 LA15 4K057 DA16 DA20 DB20 DD01 DD03 DE01 DE04 DE06 DE08 DE11 DE14 DG20 DJ02 DM02 DM05 DM06 DM40 DN01 5F004 AA01 BA04 BA14 BA16 BB11 BB14 BB18 BB28 BC08 BD07 CA09 CB02 DA00 DA01 DA04 DA11 DA18 DA23 DB00 DB01 DB03 5F045 AA08 AA13 AC02 AC03 AC05 AC16 AF01 DP01 EC03 AF01 DP01 EC02 EH06 EH08 EH11 EH13 EH14 EH16 EH17 EH19 EH20 GB08

Claims (2)

[Claims] In an apparatus for processing a substrate by generating plasma in a chamber having a supply port and an exhaust port for a plasma generating gas, a ring having a height higher than the substrate is provided outside the substrate, and a bias is applied to the ring. A plasma processing apparatus to which electric power is applied. 2. A high-frequency power is applied to each of the second electrode plates arranged in parallel with the first electrode plate to generate plasma,
In an apparatus for processing a substrate installed on a second electrode,
A plasma processing apparatus, wherein a ring having a height higher than that of a substrate is provided on a second electrode outside a substrate, and a bias voltage is applied to the ring.