JPH0138911Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plasma etching apparatus used for etching a substrate (wafer) in a semiconductor device manufacturing process.

This plasma etching apparatus can process, for example, Al,
This is used when etching substrates such as Al-Si or Al-Si-Cu. BCl ₃ , CCl ₄ ,
Using an etching gas containing Cl such as SiCl ₄ , this etching gas is turned into plasma by applying a high frequency electric field between two flat electrodes provided in the etching chamber, and the ions and neutral radicals in this plasma are transferred to the substrate. Volatile substances reacted with Al
The substrate is etched by converting it into AlCl ₃ and evaporating it.

However, since AlCl ₃ has a low vapor pressure and strong adsorption, the etching rate decreases due to the loading effect (the larger the area to be etched, the slower the etching rate at the center and faster at the outer periphery), as shown in Figure 1. An etching rate distribution occurs in which the etching rate is slower at the center of the substrate and faster at the outer periphery, and as a result, the thickness of the Al base film becomes thinner at the outer periphery.
There is also a risk that the underlying film on the outer periphery of the substrate, where the etching rate is high, will be completely etched, resulting in a significant decrease in device yield and the disadvantage that uniform etching cannot be achieved.

The present invention has been made to solve the above-mentioned drawbacks, and one embodiment thereof will be described below with reference to the drawings.

FIG. 2 shows a simplified sectional view showing the structure of the plasma etching apparatus according to the present invention, which includes a plurality of etching chambers. This embodiment includes three etching chambers 1a, 1b, and 1c. Two flat plate electrodes 2a to 2c and 3a to 3c are provided in each chamber 1a to 1c to face each other, and the upper flat plate electrode 2a to 2c is connected to a gas injection pipe 4a on the ceiling surface of each chamber 1a to 1c.
~4c is used to support the lower flat plate electrode 3a~
3c is a fixed base 5a on the bottom of each chamber 1a to 1c.
- Mounted on 5c. Upper flat plate electrode 2
a to 2c are grounded, and the lower flat plate electrode 3a
3c are water-cooled, and high frequency oscillators 6a to 6c are connected between the upper flat plate electrodes 2a to 2c.

On each of the lower flat plate electrodes 3a to 3c, there are provided substrate pushing jigs 7a to 7c for transporting the substrate, and a substrate 8 is set on the jigs 7a to 7c. In the vicinity of the setting position of the substrate 8, a substrate is placed at a position opposite to the substrate 8 which is sequentially transported by the substrate transport mechanisms 9a to 9c into the chambers 1a to 1c and set on the substrate pushing jigs 7a to 7c. Hole 1 for enlarging the etching area of No. 8 from the center to the outer periphery in three stages
Teflon jigs 11a to 11c for etching area adjustment having sizes 0a to 10c are arranged, and a Teflon jig pushing jig 1 is placed on the lower flat plate electrodes 3a to 3c.
Set by 2a to 12c.

The hole 10a of the first Teflon jig 11a is a relatively small hole with a diameter of about half the diameter of the substrate 8, as shown in FIGS. 3a and 3b, and the hole 10a of the second Teflon jig 11b is 10b is a medium-sized hole as shown in FIGS. 4a and 4b, approximately 3/4 of the diameter of the substrate 8.
The hole 10c of the third Teflon jig 11c is a relatively large hole larger than the diameter of the substrate 8, as shown in FIGS. 5a and 5b.

There are gates 1 at the front and rear of each chamber 1a to 1c.
3a ₁ to 13c ₁ and 12a ₁ to 13c ₂ are provided, and the loading chambers 14 connect the chambers 1a to 1c through these gates. Further, each of the chambers 1a to 1c is equipped with an exhaust device 15a to 15c consisting of an exhaust pump and a driving motor for evacuating the inside. A loading cassette 16 is provided in a loading chamber 14 located in front of the first chamber 1a, and contains a substrate 8 to be etched. Reference numeral 17 denotes an unloading chamber connected to the rear gate 13c ₂ side of the last (third in this example) chamber 1c, into which the etched substrate 8 is carried out from the last chamber 1c. and a cassette 19 for unloading to accommodate the unloaded substrates.
is provided. Reference numerals 20a to 20c are gas injection ports for supplying etching gas into each chamber 1a to 1c through gas injection pipes 4a to 4c.

Since the present invention has the above-mentioned configuration, first,
The substrate 8 is taken out from the cassette 16, the gate _13a1 is opened, the transfer mechanism 9a transfers it into the first chamber 1a, and the substrate is set on the substrate pushing jig 7a. Next, with the gates 13a ₁ and 13a ₂ closed, the exhaust device 15a is operated to evacuate the chamber 1a, a high frequency electric field is applied between the electrodes 2a and 3a by the high frequency oscillator 6a, and the gas injection pipe is opened from the gas injection port 20a. When etching gas is introduced into the chamber 1a through 4a, the etching gas is turned into plasma, and the ions and neutral radicals in the plasma are transferred to the substrate 8 through the hole 10a of the Teflon jig 11a.
By exposing ions and neutral radicals to the substrate 8, for example, when the substrate 8 is made of Al,
The substrate 8 is plasma etched by reacting Al with the Cl component of the etching gas to convert it into a volatile substance AlCl ₃ and evaporating it. In this chamber 1a, only the central portion of the substrate 8 corresponding to the size of the hole 10a of the Teflon jig 11a is etched. The amount of etching is about 1/4 of the thickness of the substrate 8, and the remaining thickness distribution of the substrate 8 in this case is as shown in FIG. 3c.

The substrate 8 etched in the first chamber 1a is then etched into the gate 13 in the second chamber 1b.
a ₂ , 13b ₁ are opened and transported by the transport mechanism 9b,
It is set on the substrate pushing jig 7b and plasma etched in the same manner as above. In this chamber 1b, a portion of the substrate 8 corresponding to the size of the hole 10a of the Teflon jig 11b is etched to about half the thickness of the substrate before etching. In this case, the remaining thickness distribution of the substrate 8 is as shown in FIG. 4c due to the difference in etching rate between the center and the outer periphery.

Thereafter, the substrate 8 in the second chamber 1b is transferred to the third chamber 1c, and the entire substrate 8 is plasma etched. As already mentioned, the etching rate distribution at this time is as shown in the first diagram, in which the amount of etching on the outer periphery of the substrate 8 is larger than the amount of etching on the center part, and
Since this is equivalent to the distribution of the remaining thickness of the substrate shown in Figure c, there is no difference in the remaining thickness between the center and the outer periphery of the substrate 8 when etching is completed (see Figure 5c), and the etching of the substrate 8 is uniform. be able to.

When the substrate 8 in the chamber 1a is transferred to the next chamber 1b, the substrate 8 in the chamber 1b is transferred to the next chamber 1c, and at the same time, the substrate 8 to be etched next is transferred from the cassette 16 into the chamber 1a. The substrate 8 is taken out and transported, and etching is performed by sequentially transporting the substrate 8 into the chambers 1a to 1c in this manner, and the etching is completed in the final chamber 1c. After the etching process, the substrate 8 is subjected to post-treatment (4).
(may be done by setting up a second chamber),
It is transported and stored in a cassette 19 for unloading.

The present invention can also be applied to etching a PolySi (polysilicon) substrate using an etching gas of chloride or bromide, and uniform etching can be achieved.

As described above, according to the present invention, a plurality of etching chambers are provided, and in the vicinity of the substrate setting position in each etching chamber, a position facing the substrates to be sequentially transported and set in these chambers,
Each device is equipped with an etching area adjustment jig that expands the etching area of the substrate from the center to the outer periphery in multiple stages, so even if the substrate has a large diameter, the entire surface of the substrate can be etched uniformly. In addition, it is possible to uniformly complete etching, which not only greatly improves the yield of devices, but also eliminates the need to carefully select the etching gas to be used depending on the substrate material. (the etching is larger than the center) is also extremely reduced. In addition, since the substrates are etched one after another using multiple etching chambers and the etched substrates are taken out one after another from the final chamber, the number of etched substrates is reduced to 100% compared to the conventional case where one chamber is used. This means that the etching process can be performed on each substrate one by one in a time of 1000 yen, which has the effect of increasing productivity by several times.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a typical example of the etching rate distribution of an aluminum substrate, FIG. 2 is a simplified cross-sectional view showing the configuration of an embodiment of the device of the present invention, and FIG. FIG. 3b is a cross-sectional view of the Teflon jig for adjusting the etching area in the etching chamber, and FIG. 3c is the remaining thickness distribution during etching of the substrate in this chamber. FIG. 4a is a plan view showing the arrangement relationship between the Teflon jig for adjusting the etching area and the substrate in the second etching chamber in FIG. 2, FIG. 4b is a cross-sectional view thereof, and FIG. 4c is a diagram showing the residual thickness distribution during etching of the substrate in this chamber, and FIG. 5a is a diagram showing the arrangement relationship between the Teflon jig for adjusting the etching area and the substrate in the third (final) etching chamber in FIG. 2. FIG. 5B is a sectional view thereof, and FIG. 5C is a diagram showing the remaining thickness distribution of the substrate in this chamber during etching. 1a, 1b, 1c...Etching chamber, 2
a, 2b, 2c, 3a, 3b, 3c... flat plate electrode, 4a, 4b, 4c... gas injection tube, 6a, 6
b, 6c...High frequency oscillator, 7a, 7b, 7c...
...Jig for pushing up the board, 8... Board, 9a, 9b,
9c...Substrate transport mechanism, 10a, 10b, 10c
... Hole, 11a, 11b, 11c... Teflon jig for adjusting the etching area, 12a, 12b, 12
c...Teflon jig push-up jig, 13a ₁ , 13
b ₁ , 13c ₁ , 13a ₂ , 13b ₂ , 13c ₂ ... gate, 14 ... loading chamber, 15a, 1
5b, 15c... Exhaust device.

Claims (1)

[Scope of utility model registration request] Two flat plate electrodes facing each other are provided in the etching chamber, and by applying a high frequency electric field between the two electrodes, the etching gas introduced into the etching chamber is turned into plasma, and the ions and neutral radicals in this plasma are An apparatus for plasma etching a substrate by reacting with a substrate set between electrodes to convert it into a volatile substance and evaporating it, comprising a plurality of etching chambers,
Near the substrate set position in each etching chamber, an etching process is performed to expand the etching area of the substrate from the center to the outer periphery in multiple steps at a position opposite to the substrates that are sequentially transported and set in these chambers. A plasma etching device in which a jig for area adjustment is arranged.