JPS63184337A - Wet etching device - Google Patents

Abstract

PURPOSE:To obtain stable high yield by replacing chemicals in a chemical tank by injecting chemicals having few particles and contaminants from the bottom of the chemical tank and overflowing chemicals while completing unit etching treatment and pulling out a carrier, into which a wafer is introduced, discharging chemicals from the bottom of the chemical tank and returning chemicals to a liquid storage tank through a filter. CONSTITUTION:Chemicals stored in a liquid storage tank 4 through a liquid supply pipe 8 are injected into an inner tank 2 for a chemical tank from the bottom through a filter 5a by a pump 6a. Chemicals overflowing to an outer tank 1 for the chemical tank from the inner tank 2 for the chemical tank are returned into the liquid storage tank 4 through a filter 5b by a pump 6b. Consequently, chemicals passed through the filter are injected into the inner tank 2 for the chemical tank from the bottom at all times, and chemicals including excessive particles and contaminants in plenty are brought to an overflowing state. Unit etching treatment is executed under the state, a valve 10a is opened and chemicals in the chemical tank are all returned into the liquid storage tank 4 through the filter 5b by the pump 6b. Accordingly, particles and contaminants in chemicals can be held at an extremely low level at all times in the inner tank 2 for the chemical tank during the progress of etching.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a wet etching apparatus, and more particularly to a wet etching apparatus having an etching sequence that reduces the amount of particles and contaminants attached to a wafer.

[Conventional technology]

FIG. 3 is an example of a system diagram of a conventional wet etching apparatus. The etching sequence when this device is used is that the chemical solution stored in the liquid storage tank 4 is injected into the inner tank 2 of the chemical solution tank via the filter 5 by the pump 6 through the liquid supply pipe 8. Thereafter, the overflowing chemical liquid from the inner tank 2 of the chemical liquid tank to the outer tank 1 of the chemical liquid tank passes through the chemical liquid circulation pipe 7b, enters the chemical liquid circulation pipe 7a, and returns to the inner tank 2 of the chemical liquid tank via the filter 58 by the pump 6. Injected. As a result, although the chemical liquid always passes through the filter 5, the amount is very small, so if the unit etching process is performed multiple times in this state, particles and contaminants in the chemical liquid in the chemical liquid tank will increase as the number of processes increases. As the amount increases, the amount of adhesion to the wafer also increases. 7c is a pipe, 9 is a drain pipe, 10a, 10b.

10c,llc,lld,lie,llf,l1g,l
lh is a valve.

[Problem that the invention seeks to solve]

The conventional wet etching apparatus described above performs unit etching processes multiple times using a chemical solution in a chemical tank that has a constant circulation filtering mechanism. The disadvantage is that the amount of deposited is large, making it impossible to obtain a stable high yield.

SUMMARY OF THE INVENTION An object of the present invention is to provide a wet etching apparatus that provides a stable and high yield.

[Differences between the invention and the prior art]

In contrast to the above-mentioned conventional wet etching apparatus, the present invention, when placing a wafer in a chemical bath and performing etching processing, constantly injects a chemical solution with few particles and contaminants from the bottom of the chemical bath and overflows the chemical solution. By preventing the increase in the number of particles from adhering to and re-adhering to the wafer, and by draining all the chemical solution in the chemical bath after unit etching processing, subsequent processing, which can be a problem during continuous processing, can be prevented. It has the unique content of keeping the amount of particles and contaminants adhering to the wafer at a very low level, since it can also prevent the wafer from being affected by other processes.

[Means for solving problems]

The wet etching apparatus of the present invention injects a chemical solution with few particles and contaminants from the bottom of the inner tank through a filter, and overflows the chemical solution into the outer tank at a large flow rate, thereby cleaning the inside of the chemical tank. There is a mechanism for replacing the chemical solution, and after the unit etching process is completed and the carrier containing the wafer is pulled out, the chemical solution is drained from the bottom of the chemical tank.
It is characterized by having a mechanism for returning the liquid to the storage tank via a filter.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

(Example 1) FIG. 1 is a block diagram showing a first embodiment of the present invention.

As shown in FIG. 1, the chemical solution tank of this embodiment has a double structure, inside and outside, and a filter 5a is provided at the bottom of the inner tank 2.

5b, pump 6a, valves 10g, 10h, connected to liquid storage tank 4 via chemical circulation pipe 7a, valves 10a, 10b, 10c, 10d, pump 6b
, and the liquid storage tank 4 is connected via the chemical liquid circulation pipe 7b. Further, the inner tank 2 and the outer tank 1 are connected via a valve 10a'. 9 is a drain pipe, 8 is a liquid supply pipe, 10e, 10
f is a valve.

3 is a wafer.

The chemical liquid stored in the liquid storage tank 4 through the liquid supply pipe 8 is injected into the internal tank 2 of the chemical liquid tank from the bottom via the filter 58 by the pump 6a. Thereafter, the chemical solution overflowing from the inner tank 2 to the outer tank 1 is returned to the storage tank 4 via the filter 5b by the pump 6b. As described above, in the inner tank 2 of the chemical liquid tank, the chemical liquid that has passed through the filter is always injected from the bottom, and the chemical liquid containing a large amount of excess particles and contaminants is in an overflow state. After performing the unit etching process in this state, the valve 10a is opened and all of the chemical solution in the chemical solution tank is pumped through the filter 5 by the pump 6b.
It is returned to the liquid storage tank 4 via b. When performing the next unit etching process again, a chemical solution containing few particles is supplied from the liquid storage tank 4 via the chemical solution circulation pipe 7a and the filter 58. As a result, particles and contaminants in the chemical solution can be kept at a very low level at all times in the chemical solution tank inner tank 2 while etching is in progress, so that the amount of adhesion to the wafer can also be reduced.

(Example 2) Fig. 2 is a configuration diagram showing a second example of the present invention. In this example, the bottom shape of the inner tank 2 of the chemical liquid tank of the first example is processed into a rounded and spherical shape. This is the case when used as follows. Since the bottom of the chemical solution tank is smooth, no chemical pools are formed and the replacement rate of the chemical solution is increased, so there is an advantage that the amount of attached dust can be further reduced compared to the first embodiment.

〔Effect of the invention〕

As explained above, the wet etching apparatus according to the present invention uses a pump to inject a chemical with few particles or contaminants from the bottom of the chemical tank through a filter while the wafer is placed in the chemical tank, that is, while etching is in progress. There is a mechanism that replaces the chemical solution in the chemical tank by overflowing the chemical solution with the device, and a mechanism that drains the chemical solution from the bottom of the chemical tank and stores it through a filter after the unit etching process is completed and the carrier containing the wafer is pulled out. Since it has a mechanism to return the chemical to the liquid tank, the chemical liquid is constantly replaced in the chemical liquid tank while etching is in progress, and the amount of particles and contaminants in the chemical liquid can be kept at a very low level. This has the effect of reducing the amount of adhesion to the wafer and achieving a stable high yield.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of Embodiment 1 of the wet etching apparatus of the present invention, FIG. 2 is a system diagram of Embodiment 2 of the wet etching apparatus of the present invention, and FIG. 3 is a system diagram of a conventional wet etching apparatus. . 1... Outer tank for chemical solution tank 2... Inner tank for chemical solution tank 3.
...Wafer 4...Liquid storage tank 5a, 5
b...Filter 6a, 6b...Pump 7a, 7b...Medical solution circulation pipe 8...Liquid supply pipe 9...Drainage pipe

Claims (1)

[Claims] (1) The chemical liquid in the chemical liquid tank is replaced by injecting the chemical liquid with few particles and contaminants from the bottom of the inner tank through a filter and overflowing the chemical liquid into the outer tank of the chemical liquid tank at a large flow rate. A wet etching apparatus comprising: a mechanism; and a mechanism that drains the chemical solution from the bottom of the chemical tank and returns it to the liquid storage tank via a filter after unit etching processing is completed and the carrier containing the wafer is pulled out. .