JPH02122523A - Dry etching method and apparatus therefor - Google Patents

Abstract

PURPOSE:To enable a wafer to be etched uniformly, achieve a high etching rate, and also reduce damage to the wafer by placing a cathode magnet and a counter magnet and then forming a uniform magnetic field for generating plasma in a parallel plate type RIE generator. CONSTITUTION:A Ca magnet 2 is placed at a cathode within an E chamber 1 and a Cu magnet 3 is placed near the upper surface of the cathode outside the upper E chamber 1 for enabling magnetic field near the upper surface of the cathode to be uniform. The Ca magnet 2 and the Cu magnet 3 are in parallel and the direction of magnetic flux is agreed. Furthermore, a gas shower plate 4 which is a discharge hole of etching gas as an anode electrode is provided. Then, gas is uniformly supplied by the gas shower plate 4, pressure within the E chamber 1 is made constant, and then a high-frequency power is applied between a cathode 6 and the gas shower plate which is an anode. Then, plasma is generated at the upper part of a wafer 5 and it is generated from a region where magnetic flux concentration is uniform, thus enabling generated plasma concentration to be equally uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a dry etching method and apparatus used for manufacturing semiconductor devices.

(Prior art) Figure 8 shows a conventional RI for etching a semiconductor substrate, etc.
E (Reactiva Ion Etching:
1 is a cross-sectional view schematically showing a reactive etching (reactive etching) apparatus, which is a so-called parallel plate type RIE apparatus in which flat plate electrodes are arranged in parallel, and an object to be etched, for example, a wafer 22, is attached to a cathode 21 of one of the electrodes. The wafer 22 can be plasma etched by placing the wafer 22 on the wafer 22 and applying high frequency power to the cathode 21 to generate plasma. Note that 23 is an etching chamber, and 24 is a gas shower plate into which etching raw material gas is introduced.

In addition, FIGS. 9(a) and 9(b) show magnetron ion etching (Magnetron Ion Etching) in which a magnet M is added to the RIE apparatus, respectively.
8 is a sectional view of a device (hereinafter referred to as MIE), and the reference numerals refer to the explanation of the reference numerals in FIG. 8. The MIE device is shown in Figure 9 (
Only the cathode 21 side as in a) or as in Fig. 9(b)
Shower plate 24 which functions as an anode as in
Uniform plasma etching was performed by providing a plurality of magnets M only on the sides and vibrating them (left and right) in the direction of the S-+N magnetic field lines as shown by the arrows.

(Problems to be Solved by the Invention) However, the RIE apparatus shown in FIG. 8 has the disadvantage that the etching rate is small due to the low plasma density generated, resulting in low etching processing capacity and poor productivity. Even if the number of high-frequency electrodes applied is increased in order to improve the etching ion energy, the etching ion energy increases, resulting in deterioration of the characteristics of the semiconductor device. In addition, the etching ion energy varies widely, and even if etching is performed with an average low ion energy,
There is a drawback that etching ions with high energy are mixed in some parts and the high ion energy is incident, resulting in deterioration of the characteristics of the semiconductor device formed from the object to be etched.

Furthermore, in such an RIE apparatus, plasma discharge cannot be performed unless the degree of vacuum is several tens of m Torr or more, and it is not suitable for performing anisotropic etching such as ultrafine processing.

In addition, in conventional MIE equipment, in order to ensure uniformity of etching rate within the wafer surface, magnet M [9th
Figures (a) and (b)) are vibrated in the direction of magnetic lines of force, that is, parallel to the wafer surface (left and right), but it is necessary to average the differences in plasma density over time. At this time, in the part where the magnetic flux density changes rapidly.

In other words, the plasma density increases between each magnet individual,
This method has the drawbacks of causing a plasma density difference, damaging the wafer, and causing defects such as poor electric withstand voltage of the oxide film.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a dry etching method and apparatus which eliminates the drawbacks of the prior art as described above.

(Means for Solving the Problems) The present invention achieves the above object based on a configuration in which a cathode magnet and a counter magnet are arranged in a parallel plate type RIE generator, thereby forming a uniform magnetic field to generate plasma. Etching uniformity can be improved by rotating the cathode magnet, counter magnet, rotating the wafer in a uniform magnetic field, changing the gas blowing holes, etc.

(Function) According to the method of the present invention configured as described above, the cathode magnet or counter magnet in which the magnetic pole plate is coupled to the magnetic pole of the permanent magnet forms a uniform magnetic field over a wide range, and therefore, the present invention apparatus using the cathode magnet or counter magnet forms a uniform magnetic field over a wide range. In this case, the magnetic field lines near the surface of the object to be etched placed on the cathode are formed almost uniformly, and the magnetic east density distribution is almost equal in the plasma generation region between the cathode and the anode.
The generated plasma is uniform, and the object to be etched 1, for example, a wafer, can be etched uniformly.

Furthermore, since the plasma generation region has a high magnetic field density, a high etching rate can be obtained, and furthermore, the accelerating voltage for etching ions in the sheath region is reduced, so that damage to the wafer can be reduced.

(Example) Embodiments of the present invention will be described in detail below with reference to the drawings.

FIGS. 1 to 3 are diagrams showing a first embodiment of the present invention, and respectively include a transparent perspective view showing the concept of the device, a diagram explaining the lines of magnetic force of the main part, and a sectional view of the device. It is.

In Figures 1 to 7, 1 is an etching chamber (hereinafter abbreviated as E-chamber), 2 is a cathode magnet (hereinafter abbreviated as Ca-magnet), and 3 is a counter magnet (hereinafter abbreviated as Cu-magnet). , 4
Gas shower play 1~. 5 is a wafer as an object to be etched, and 6 is a cathode.

In the device of the present invention, a Ca magnet 2 is placed in the cathode section within the E chamber 1 as shown in the figure.

-1 Part E. A Cu magnet 3 is arranged outside the chamber 1 to keep the magnetic field near the top surface of the cathode constant. ++ Ca magnet 2 and Cu magnet 3 are parallel to each other and in the magnetic flux direction. (direction from S to N). Furthermore, a gas shower plate 4 is installed as an anode electrode, which is a blowing hole for etching gas (hereinafter referred to as Qt). Note that the Ca magnet 2 or the Cu magnet 3 is configured to fix a magnetic pole plate to each of the two poles using several rod-shaped permanent magnets to make the magnetic field uniform.

Figure 2 shows the magnetic lines of force of Ca magnet 2 bent by Cu magnet 3;
・In the vicinity of magnet 2.

Because of the Cu magnet 3, the lines of magnetic force are almost uniform and parallel. In the figure, 7, 8, 9 and 10 are magnetic pole plates.

FIG. 3 is a sectional view of the first embodiment of the apparatus taken along the line A-I'3 shown in FIG. When gas is uniformly supplied by the gas shower plate 4, the pressure inside the E-chamber 1 is kept constant, and high frequency power is applied between the cathode 6 and the gas shower plate 4, which serves as an anode, plasma is generated above the wafer 5. However, as explained in FIG. 2, since the magnetic flux density (lines of magnetic force) is generated in a uniform region, the generated plasma density is also uniform. That is, the configuration shown in FIG. 3 allows uniform etching of the wafer 5.

Embodiment 2 FIGS. 4(a) and 4(b) are top views of the gas shower plate 4, which constitutes the main part of the second embodiment.

Even with the apparatus of the first embodiment described above, there is still a slight difference in the etching rate in the CD direction (FIG. 1), and the etching rate tends to be small on the C side and large on the D side. this is,
According to Fleming's law, etching ions with plasma charges cross the magnetic flux perpendicularly from the side of the gas shower plate 4 toward the cathode 6, so that the etching ions receive a force to the right along the magnetic flux direction from S to N. arise.

In the second embodiment, in order to solve the imbalance of the above-mentioned erating layer 1-, a plurality of gas blowing holes are formed in the gas shower plate 4, as shown in FIGS. 4(a) and 4(b). By arranging more gases on the C-direction side than on the C-direction side, it is possible to provide an average gas supply and eliminate the difference in etching rate.

Note that FIG. 4(a) shows a case in which the arrangement density of the gas blowing holes H is different, and FIG. 4(b) shows a case in which gas blowing holes are provided only on one side.

Embodiment 3 FIG. 5 is a cross-sectional view of a device according to a third embodiment, which is constructed almost in the same way as the first embodiment.

As explained in the second embodiment, the etching rate is small on the C direction side of the device and large on the D direction side.

Therefore, as shown in Fig. 5, Cu magnet 3 and Ca
・The opposing distance with the magnet 2 is made larger on the C direction side where the etching rate is higher than on the other side, thereby making the magnetic flux distribution above the wafer 5 smaller on the C direction side and lowering the plasma density on the C direction side. This eliminates the non-uniformity of etching rate.

Example 4 FIG. 6 is a sectional view of the device of the fourth embodiment.

Based on the same principle as the first embodiment device of FIG.

Although the magnetic flux density between the cathode 6 and the gas shower plate 4 is made uniform to generate plasma and the wafer 5 placed on the cathode 6 is etched, the etching rate remains non-uniform.

The fourth embodiment uses Cu magnet 3 and Ca
- By simultaneously rotating the magnets 2 in their plane directions, the magnetic flux near the wafer 5 is averaged and eliminated.

That is, reference numeral 11 denotes a rotating shaft rotated by a drive source provided elsewhere, to which a rotating gear 12 is fixed, and by rotating the rotating shaft 14 via the rotating gear 13, the Ca magnet 2 is rotated. Similarly, a rotating gear 15 driven by the rotating shaft 11 and a rotating gear 1 engaged with the rotating gear 15 are driven by the rotating shaft 11.
Rotate +1 illll 17 through 6 and rotate the Cu magnet 3 fixed thereto to the above Ca magnet 2.
By simultaneously rotating in the same direction as the rotation of the wafer 5, the magnetic flux to the wafer 5 is kept uniform. That is, this rotation eliminates differences in magnetic flux density distribution and non-uniformity in etching rate, allowing uniform etching to be performed.

In addition, Ca magnet 2. Even when the Cu magnet 3 rotates, there is almost no change in the magnetic flux density, so the plasma density is almost constant over the entire area of the wafer 5, and no damage to the wafer occurs due to a difference in plasma density.

Embodiment 5 FIG. 7 is a sectional view of an apparatus explaining a fifth embodiment. Using the same principle as the first embodiment, Ca/magnet 2 and Cu
- The magnet 3 is arranged so that the magnetic flux density between the cathode 6 and the gas shower plate 4 is uniform, and high frequency power is applied to etch the wafer 5 on the cathode 6. Rate heterogeneity remains.

In this fifth embodiment, a rotating shaft 18 is connected to the cathode 6, and by rotationally driving the rotating shaft 18, the cathode 6 and the wafer 5 placed thereon are connected to a Ca magnet 2. Rotate in the magnetic flux of Cu magnet 3.

The rotation eliminates the effects of differences in magnetic flux density distribution and non-uniform etching rates, and in this embodiment, as in the fourth embodiment, even if the wafer 5 rotates within the magnetic field, it is etched almost uniformly. Since it is within the plasma density, damage to the wafer caused by plasma density differences does not occur.

(Effects of the Invention) As is clear from the detailed explanation above, the present invention provides MI
The advantage of E is that high-rate etching is possible due to high-density ions, and high etching processing capacity can be obtained. Also,
Since etching is carried out by plasma in a uniform magnetic field, the wafer has the advantage of not being damaged, and its implementation is highly effective.

[Brief explanation of the drawing]

Fig. 1 is a transparent perspective view showing the main parts of the dry etching apparatus of the present invention, Fig. 2 is a diagram showing the lines of magnetic force of the main parts to explain the principle, and Fig. 3 is a schematic diagram of the apparatus showing the first embodiment. cross section,
FIG. 4 is a top view of the main parts showing the second embodiment, FIG. 5 is a schematic sectional view of the device showing the third embodiment, and FIG. 6 is a schematic configuration diagram explaining the fourth embodiment. FIG. 7 is a schematic configuration diagram for explaining the fifth embodiment, FIG. 8 is a schematic sectional view of a conventional RIE apparatus, and FIG. 9 is a schematic sectional view of the same <MIE apparatus. 1... Etching chamber (E-chamber),
2... Cathode magnet (Ca magnet),
3... Counter magnet (Cu magnet), 4... Gas shower plate, 5...
Wafer, 6... Cathode, 7, 8, 9.
10... Magnetic pole plate, 11.14°17, 18... Rotating shaft, 12, 13, 15.16... Rotating gear.

Claims (6)

[Claims] (1) A permanent magnet device in which magnetic pole plates are fixed to both poles of a permanent magnet is aligned with the cathode electrode inside the etching chamber and the anode electrode outside the etching chamber so that the magnetic pole direction is aligned with the parallel plate electrode. Plasma etching is performed by placing the etching gas blowing plate in parallel between the cathode magnet and the counter magnet in an etching chamber, using it as a cathode magnet and a counter magnet, and using an etching gas blowing plate having a plurality of gas blowing holes as an anode electrode. Characteristic dry etching method. (2) In a parallel plate type plasma generator, a permanent magnet device in which magnetic pole plates are fixed to both poles of a permanent magnet is aligned with the magnetic pole direction of the cathode electrode inside the etching chamber and the anode electrode outside the etching chamber. The etching gas blowing plate has a plurality of gas blowing holes in the space between the cathode magnet and the counter magnet, and is arranged in parallel with the parallel plate electrode as an anode electrode. dry etching equipment. (3) The dryer according to claim (2), wherein the gas blowing plate has a plurality of etching gas blowing holes provided in the gas blowing plate arranged so as to blow out a large amount of gas to the left side in the magnetic flux direction of the cathode magnet. Etching equipment. (4) The dry etching apparatus according to claim (2), wherein the spacing between the cathode magnet and the counter magnet is larger on the right side as viewed in the direction of their magnetic flux than on the other side. (5) The dry etching apparatus according to claim (2), wherein the cathode magnet and the counter magnet are configured to rotate in parallel with the parallel plate electrodes at the same period. (6) The dry etching apparatus according to claim (2), wherein the anode electrode rotates parallel to the cathode magnet and the counter magnet.