JP2000150472A - Plasma process device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow high selectivity in etching with a multi-layer film and to provide high selectivity and etching form in a substrate, by providing the surface of a first plate which faces a wafer having a rough surface for lower needless radical concentration. SOLUTION: A recessed part 2b is provided on the surface of a first plate 2 facing a substrate 4. Since a surface area increases and an area to which F radical sticks increases, more fluorine radical is consumed at the first plate 2. As a result, the amount of fluorine radical in a chamber 1 significantly decreases, the amount of fluorine radical incident on the substrate 4 decreases, and the etching rate of an Si and Si3N4 film of base material lowers. As a result, a selective ratio relative to the base material improves. Since the fluorine radical is consumed over the second surface of the entire first plate, the amount of fluorine radical incident on the substrate is even in the substrate, so the selective ratio is even in the substrate. Thus, productivity improves.

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 processing a substrate such as a semiconductor element substrate or a liquid crystal substrate using a gas dissociated by plasma. The present invention relates to a plasma processing apparatus suitable for controlling a processing speed in a substrate 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. 6-163467, a substrate treatment is performed by making the distribution of reaction products in a substrate uniform by the diameter of a showerhead. Attempts have been made to make the speed uniform.

[0003]

In the etching of a semiconductor element, 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. In the plasma, the gas dissociates, 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 to improve the selectivity of the film to be etched with respect to the base, it is necessary to uniformly reduce the amount of radicals that react with the base within the substrate.

For example, in etching a silicon dioxide film using fluorocarbon, it is necessary to reduce fluorine radicals in order to improve the selectivity to underlying silicon or silicon nitride. For example, C ₄ as fluorocarbon
When F ₈ is used as an etching gas, radicals having various composition ratios of carbon and fluorine are generated in plasma. Among them, radicals directly related to the etching reaction are CF ₃ , CF ₂ , CF, F. It is called a radical. Among them, the fluorine (F) radical is SiO ₂ <Si ₃
Since the reaction probability increases in the order of N ₄ <Si, the underlying Si
To lower the etching rate of the or Si ₃ N _4, it is necessary to reduce the amount of fluorine radicals.

In the prior art, amorphous carbon is used as the material of the upper electrode, and the amount of fluorine radicals is reduced by reacting fluorine radicals and amorphous carbon. That was not enough to reduce fluorine radicals.

[0006]

According to the present invention, in order to solve the above problems, the surface of the first plate facing the wafer is provided with irregularities to reduce the concentration of unnecessary radicals.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a sectional view of a plasma processing apparatus according to the method of the present invention. Here, an etching process will be described as an example. A substrate 4 is placed on a second plate 3 disposed inside the chamber 1 so as to face the first plate 2. Coaxial cable 1 for supplying 450 MHz electromagnetic wave to chamber 1
1 and is connected to a 450 MHz power supply (not shown). 450 MHz electromagnetic wave is transmitted through the quartz block 12
And is introduced into the chamber 1.

An electromagnetic coil 13 is provided outside the chamber 1 to generate a magnetic field. The frequency of the electromagnetic wave is 450
At MHz, electron cyclotron resonance (ECR) occurs at a magnetic field strength of 0.0161 Tesla (161 Gauss).
Thus, the processing chamber 6 between the first plate 2 and the second plate 3
Inside, a plasma 7 is generated to process the substrate 4. An RF (high frequency) auxiliary power supply 5a,
5b is connected.

The central portion of the first plate 2 has a large number of gas holes 2a, and is connected to 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 plate 3 and is evacuated by a vacuum pump (not shown). The first plate 2 is made of carbon, silicon, or the like.

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 , Cl ₂ , BCl ₃ , SF ₆ , HB
A gas such as r is used depending on the film to be etched.

The above apparatus was patterned with a mixed gas of argon and a fluorocarbon-based gas such as CF ₄ or C ₄ F ₈ as a plasma generating gas.
It is assumed that the SiO ₂ film is etched. Except for the location of the patterned SiO ₂ film, the resist film covers the surface. The underlying films are a Si film and a Si ₃ N ₄ film. When this gas is supplied from the gas supply means 8 to the gas hole 2 a of the first plate 2, the gas flows from this hole into the processing chamber 6 and is discharged from the exhaust port 9.

When an electromagnetic wave of 450 MHz is supplied to the antenna 11 to generate the plasma 7, the gas is ionized and dissociated in the plasma to generate ions and radicals, and these ions and radicals enter the substrate 4. Then, the substrate is etched. The ions are accelerated by the bias voltage applied to the second plate 3 by the high frequency auxiliary power supply 5b, and promote the etching of the substrate 4.

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 with respect to Si, the material of the first plate is made of silicon to reduce the amount of fluorine radicals, A bias voltage is applied to the first plate 2 by the auxiliary power supply 5a. Then, the fluorine radical reacts with the first plate 2 and is consumed, so that the concentration of the fluorine radical on the substrate 4 decreases.

On the other hand, the CF radicals are not consumed by the silicon plate, but etch the SiO ₂ film on the substrate 4. On the other hand, by providing the concave portion 2 b on the surface of the first plate 2 facing the substrate 4, the surface area increases and the area to which the F radical adheres increases, so that more fluorine radicals are generated on the first plate 2. Will be consumed.

FIG. 2 is a plan view of the recess 2b. The concave portion 2b is a ring-shaped concave portion.
Irregularities are formed on the surface of the substrate, and the surface area increases. The depth of the irregularities varies depending on the gas used and the process, but several μm
m to several mm. Although the concave and convex grooves are ring-shaped here, they may be divided on the way. At the time of processing the unevenness, it is preferable that sharp portions are eliminated by providing C and R at the corners.

As a result, the amount of fluorine radicals in the chamber is greatly reduced, the amount of fluorine radicals incident on the substrate 4 is reduced, and the etching rate of the underlying Si or Si ₃ N ₄ film is reduced. This has the effect of improving the selectivity for. In addition, since fluorine radicals are consumed over the entire surface of the first plate 2, the amount of fluorine radicals incident on the substrate becomes uniform in the substrate, so that the selectivity is uniform in the substrate. .

FIG. 3 shows an embodiment in which the present invention is applied to a parallel plate capacitively coupled plasma apparatus. The first plate 2 is connected to a high frequency power supply 5a, and the second plate 3 is connected to a high frequency power supply 5b. Plasma 7 is generated in the processing chamber 6 between the first plate 2 and the second plate 3 to process the substrate 4.
In such a configuration, a concave portion 2b is provided on the surface of the first plate 2 as in FIG. This embodiment is used for a higher pressure process than the embodiment of FIG.

FIG. 4 shows another embodiment of the present invention, in which the cross section of the concave portion is the same as that of FIG. 1, but separate concave portions are formed. With such a configuration, there is an effect that the gas from the gas hole 2a is sufficiently expanded and then mixed with the gas from the other gas holes.

FIG. 5 shows another embodiment of the present invention, in which the concave portion is narrower than the convex portion and forms a linear intersecting groove. With such a configuration, there is an effect that processing is facilitated.

FIG. 6 shows another embodiment of the present invention, in which the cross section of the concave portion forms a triangular groove. The plan view may be concentric grooves, orthogonal grooves, or holes. With such a configuration, there is an effect that processing is facilitated.

FIG. 7 shows another embodiment of the present invention, in which the concave portion has a small surface roughness (texture) or
A porous hole is formed. When a large number of substrates are etched, the surface of the first plate 2 is also shaved. At this time, the surface area changes from the initial case, but as in the present invention, from the beginning,
If the surface area is increased by increasing the surface roughness, there is an effect that the area of this surface does not change during etching and the etching performance does not change with time (the effect of preventing a change with time).

FIG. 8 shows another embodiment of the present invention.
In the embodiment shown in FIGS. 1 to 7, the surface area is uniformly increased in the plane of the first plate 2, whereas in FIG. 8, the surface area is changed only in a certain part. Thus, by changing the surface area only partially, the rate of consumption of radicals within the surface of the substrate 4 can be changed, and the distribution of radicals can be controlled.

For example, when radicals are large near the outer periphery and the amount of radicals is not uniform on the substrate, the surface area of the first plate 2 near the outer periphery is increased, so that the amount of radicals becomes uniform in the substrate. Etching with a uniform selection ratio can be realized within the above.

FIG. 9 shows another embodiment of the present invention.
A concavity 2b is formed by providing a multistage hole on the surface of the first plate 2 with concentric holes. By forming in this manner, the surface area increases and the distance to the substrate changes in the radial direction. When the depth of the hole becomes deeper toward the center as in this example, the plasma is concentrated at the center, which has the effect of improving the plasma density. Such a configuration has an effect that unnecessary consumption of radicals and improvement in plasma density can be achieved at the same time.

FIG. 10 shows another embodiment of the present invention. The recess 2b has a shape that is smoothly connected by connecting the truncated cones. With such a configuration, there is an effect that the electric field is not concentrated at the corners and fine particles are hardly generated. Further, the shape of the above concave portion may be an arbitrary smooth curve. The same effect is obtained by increasing the surface area. The smoother the curve, the less the electric field concentration and the generation of fine particles, and the higher the productivity of the plasma device.

The above is an embodiment of a UHF electromagnetic wave ECR plasma apparatus and a parallel plate high-frequency application type plasma apparatus. Alternatively, a bias may be applied to a surface corresponding to a substrate such as a parallel plate magnetron plasma apparatus or an inductively coupled plasma apparatus. As long as the device can load a voltage, it can be implemented in common. Further, the present invention can be applied to a plasma CVD apparatus.

[0027]

According to the present invention, there is an effect that the selectivity is high, the selectivity and the etching shape are uniform in the substrate, and the productivity is improved. .

[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 plate of FIG. 1;

FIG. 3 is a sectional view of a plasma processing apparatus according to another embodiment of the present invention.

FIG. 4 is a plan view of a first plate used in FIG. 3;

FIG. 5 is a plan view of another first plate used in FIG. 3;

FIG. 6 is a side sectional view of a first plate according to another embodiment of the present invention.

FIG. 7 is a plan view of a first plate according to another embodiment of the present invention.

FIG. 8 is a plan view of a first plate according to another embodiment of the present invention.

FIG. 9 is a side sectional view of a first plate according to another embodiment of the present invention.

FIG. 10 is a side sectional view of a first plate according to another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Chamber, 2 ... 1st board, 2a ... Gas hole, 2b ... Concavo-convex, 3 ... 2nd board, 4 ... Substrate, 5a, 5b ... Power supply, 6 ... Processing chamber, 7 ... Plasma, 8 ... Gas supply means, 9 ... exhaust port,
11: antenna, 12: quartz window, 13: electromagnetic coil.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05H 1/46 H05H 1/46 M (72) Inventor Tsutomu Tsudachi 502 Kandatecho, Tsuchiura-shi, Ibaraki Pref. F-term in Hitachi Machinery Laboratory (reference) 4K030 BA44 DA08 FA03 KA15 KA17 KA30 KA46 4K057 DA13 DA16 DA20 DD01 DM05 DM17 DM18 DM22 DM28 DM37 5F004 AA01 AA02 BA04 BA16 BA20 BB13 BB29 CA06 DA00 DA01 DA04 DA11 DA18 DA23 A EB02 EC05 EE20 EF05 EH02 EH05 EH11 EH12 EH13 EH17 EH19

Claims (1)

[Claims] 1. An apparatus for generating plasma between a first plate and a second plate disposed opposite to the first plate to process a substrate placed on the second plate, wherein a plasma is generated on a surface of the first plate facing the substrate. A plasma processing apparatus having an uneven shape.