JPS59219476A - Etching device - Google Patents

Abstract

PURPOSE:To maintain a uniform etching speed over the entire surface of a wafer by dispersing and regulating the flow of the etching soln. to be fed from a main liquid tank to a reaction vessel by means of a perforated plate supported by a slit plate from the liquid dispersing caps at the ends of branch pipes through distributing pipes and the branch pipes thereof and introducing the liquid into the reaction vessel. CONSTITUTION:An etching device is coupled with a main liquid tank 1 and a reaction vessel 10. An etching liquid is introduced from the tank 1 through a circulating pump 2 and a filter 3 to the vessel 10. The etching liquid is passed through distributing pipes 4 and branch pipes 5 thereof and is fed into the vessel 10 after the flow thereof is dispersed and regulated by a perforated plate 7 supported by a slit plate 8 from the liquid dispersing caps 6 at the top ends of the pipes 5. The etching liquid past the plate 7 is therefore supplied in the form of the liquid having a uniform flow rate distribution in the vertical and transverse direction to the vessel 10.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a new and improved structure of an etching apparatus capable of etching thin plates such as semiconductor wafers while maintaining extremely high flatness and parallelism.

When processing a wafer from a semiconductor single crystal, a strained layer is generated on the surface of the wafer due to mechanical processing.

This strained layer can be chemically removed by etching, but in order to obtain a wafer with high flatness and parallelism, C: is an etching solution (hereinafter referred to as (referred to as liquid), and the strained layer of uniform thickness must be removed.

Fig. 1 shows an outline of a conventional etching apparatus used for this purpose, which mainly consists of a main liquid tank 21 and a reaction tank 22, and a liquid circulation pump 2 in the main liquid tank.
5. The liquid enters the overflow tank 26 on the liquid inlet side of the reaction tank 22 through the filter 26, and then exits from the overflow tank 24 on the liquid outlet side and returns to the main liquid 'FI' 21. Reaction tank 2
2 is a basket 2 in which a large number of wafers 27 are stored.
8 is immersed, and the basket rotates (2) and swings downward.

However, in such conventional devices, the flow velocity distribution of the liquid in the reaction tank is uneven at each position, and
The bottom initial liquid on the side and outlet side remains, and the reaction product remains in the reaction 111, resulting in non-uniformity of the liquid. In addition, in order to speed up the exchange of the liquid, the flow rate is high.The speed of the liquid that overflows from the overflow tank 26 on the liquid input 1 side and flows into the reaction tank is increased in the lateral direction (the way the wafers are arranged). This results in uneven flow of the liquid, and a large turbulent flow of the liquid within the reaction tank, which disturbs the flow velocity distribution within the tank. For this reason, it was not possible to avoid the disadvantages of causing an inconsistency in the reaction rate on the surface of the wafer, reducing flatness and parallelism to the wafer, and causing variations.

In view of the current situation, the present invention provides a device that does not have any of the above-mentioned disadvantages.

In other words, an etching device consisting of a main liquid tank and a reaction tank (2) The liquid sent from the main liquid tank to the reaction tank via a circulation pump and a filter passes through a distribution pipe and its branch pipes. The liquid is dispersed and rectified from the liquid dispersion cap at the tip of the branch pipe to a perforated plate supported by a slit plate, and then fed into the reaction tank (two times).

The present invention will be explained in more detail below with reference to the accompanying drawings.

The second figure schematically shows a typical embodiment of the etching apparatus of the present invention, in which 1 is a main liquid tank equipped with a liquid cooling/heating mechanism (not shown), and 2 is a liquid circulation system. pump, 6
is a filter, and 4 is a distribution pipe. In this embodiment,
The liquid passes through the liquid circulation pump from the main liquid tank and passes through the filter 6.
1, reaction products are removed and sent to distribution pipe 4. As shown in the enlarged view shown in FIG. 3, this distribution pipe 4 has two or several symmetrical branch pipes 5 in two stages or multiple stages (two connected), and the liquid is transported through these distribution pipes/branch pipes. The flow rate is adjusted to be uniform by
11-l is released from the cap 6. This cap 6
As shown in the enlarged view of the gap and its surroundings shown in Figure 84, a large number of small holes are arranged concentrically with the tip of the branch pipe and angled in the direction of spreading from the center. As a result, the liquid passes through this cap and is evenly distributed. This ejected flow hits the perforated plate 7, which has small porous holes, and diffuses due to resistance. death,
When the liquid passes through all the air holes and enters the anti-uniform core tank 10, it becomes a rectified and undisturbed liquid flow C:, and has an even flow velocity distribution in the vertical and lateral directions. A suitable perforated plate is a PVA or Teflon plate provided with fine holes having a diameter of 50 fim, preferably 100 μm. 8 is a slit plate that supports the perforated plate 7, and is inserted into a large number of comb-shaped grooves on the top and bottom of the frame plate 9, and is arranged horizontally at equal intervals f2, resulting in a large number of narrow slots as a whole. A slit is formed to support water pressure from the liquid dispersion cap.

In this way, the liquid that has passed through the perforated plate 7 is supplied to the reaction tank 10 with a completely uniform flow velocity distribution in the vertical and lateral directions.

According to FIG. 2, a large number of wafers 14 are stored in a basket 15 supported by an arm 16 and immersed in a reaction tank, and as the basket 15 rotates, the wafers 14 rotate and the arm 16
It swings up and down from a swinging device 17f2 directly connected to. 11
is the reaction tank outlet side plate, and small holes are made evenly across the two face plates f, so that a part of the liquid that has passed through the reaction tank overflows the reaction tank outlet side plate 11, and the remaining liquid is passed through the reaction tank outlet. It passes through a small hole in the side plate and enters the overflow tank 12.

As a result, the liquid moves from the overflow tank 4110 to the overflow tank 12 while maintaining a uniform flow velocity up to the very vicinity of the reaction tank outlet side plate without staying at the bottom of the outlet side of the reaction tank 1 and 6. Reference numeral 16 denotes a stirring pump, which sucks the liquid from the main liquid tank 1 and discharges it back into the main liquid tank 1, thereby stirring and homogenizing the liquid in the main liquid tank and improving the efficiency of the heat exchanger. .

Reference numeral 18 denotes a water i'5t tank, which is provided close to the overflow tank 12.

This will be explained below with reference to examples, but the following examples are just examples, and it goes without saying that the conditions must be selected in consideration of the relationship with the liquid composition, liquid temperature, etc.

Example Using the apparatus of the present invention shown in the drawings, the moving speed of the liquid in the etching tank was set to 50 blades/second, the arm was gently oscillated up and down with a stroke of 100 runs, and the basket was rotated 20 times/minute. As a result of performing etching process 3 while rotating the wafer, a wafer with extremely high flatness and parallelism could be obtained.

Since the etching '1ftW according to the present invention has the above configuration, the liquid whose temperature and flow rate are precisely controlled circulates at high speed, and a uniform etching rate is maintained over the entire surface of the wafer regardless of the passage of time. It is possible to obtain a wafer with extremely high flatness and parallelism. Furthermore, it becomes easy to provide a plurality of baskets containing wafers and perform etching and washing in succession, thereby achieving high throughput. Furthermore, as is clear from FIG. 2, the apparatus of the present invention has a structure in which the main liquid tank 1, the reaction tank 10, the overflow tank 12, and the washing tank 18 are integrated, so the whole is extremely compact. The device is not only economical, but also requires a small installation area, and it is easy to automate the device by continuously operating the etching basket1), so its practical effects are extremely large. .

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of a conventionally used etching device. FIG. 2 is a schematic diagram showing a typical embodiment of the etching apparatus of the present invention. FIG. 3 is a perspective view of the distribution pipe and its branch pipes in the etching apparatus of the present invention. FIG. 4 is a vertical l';f+ side view of the liquid dispersion cap in the etching apparatus of the present invention. 1... Main liquid tank, 2... Liquid Mi ring pump, 6...
...filter, 4...distribution pipe, 5...branch pipe,
6...Liquid dispersion cap, 7...Perforated plate, 8...
・Slit loss, 9... Frame lag, 10... Reaction 4i!
, 11... Reaction tank outlet side plate, 12... Overflow tank, 16... Stirring pump 714... Wafer, 15... Basket, 16... Arm,
17... Rocking device, 18... Washing tank, 21...
・Main liquid tank, 22... Reaction tank, 26... One overflow tank on the liquid inlet side, 24... One overflow tank on the liquid outlet side, 25... Liquid circulation pump, 26... Filter,
27...wafer, 28...basket. Patent applicant Shin-Etsu Semiconductor Co., Ltd.

Claims (1)

[Claims] 1. Etching device C formed by combining a main liquid tank and a reaction tank
In step 2, the etching liquid sent from the main liquid tank through the circulation pump and filter to the reaction tank C2 passes through the distribution pipe and its branch pipes, and is supported by a slit plate from the liquid dispersion cap at the tip of the branch pipe. The flow is dispersed and rectified through a perforated plate and sent to a reaction tank (
An etching device characterized by two feedings. 2. A liquid dispersion cap attached to the tip of the branch pipe (27), a perforated plate to disperse and rectify the etching liquid ejected from the small holes of the cap, and a slit plate to support the perforated plate are installed. 3. The etching apparatus according to claim 1, characterized in that the main liquid tank has a companion pump.