JPH05217988A - Washing device - Google Patents

Abstract

PURPOSE:To wash a semiconductor substrate without shortening the life time of the same by a method wherein metals, eluated out of a carrier or the pipeline system of a washing device, are removed. CONSTITUTION:A washing device is provided with a pipeline system, including an acidic chemical solution supplying pipe 10 connected to a pipeline system constituted of an acidic chemical solution tank for washing a carrier, a washing tank 11, a pure water supplying pipe 12, chemical solution supplying pipes 13, 14 and a circulating pipeline 15, to resolve metals eluated by alkaline chemical solution by the acidic chemical solution and wash them out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning apparatus for cleaning a semiconductor substrate (hereinafter referred to as a wafer) after or before processing.

[0002]

2. Description of the Related Art FIG. 8 is a diagram showing a configuration of an example of a conventional cleaning apparatus, and FIG. 9 is a schematic sectional view of a cleaning tank in FIG. Conventionally, this type of cleaning apparatus includes, for example, as shown in FIG. 8, a wafer transfer mechanism 30a arranged at one end side for transferring the wafer to a cleaning carrier, and a cleaning tank 11 for cleaning the wafer by immersing the carrier in a chemical solution. And the cleaning tank 11
A shower tank 32 for spraying a cleaning liquid on the wafer treated in step 1 to wash away the chemical, a washing tank 33 for further washing the wafer washed in the shower tank 32, a dryer 34 for drying the washed wafer, and a washing And a wafer transfer mechanism 30b for transferring another wafer to another carrier. In addition, the cleaning devices were arranged in a line in the order of the steps.

On the other hand, as shown in FIG. 9, the cleaning tank in this cleaning apparatus includes a cleaning tank 11 for storing a cleaning liquid, a valve 17 and a filter 16 for supplying a chemical liquid to the cleaning tank 11.
Pure water supply pipe 12 and chemical liquid supply pipes 13, 1
4, a pump 18 for pumping the chemical liquid overflowing to the outer tank 19, a filter 16 for filtering the chemical liquid, and a circulation device having a circulation pipe 15 for returning the chemical liquid filtered to the cleaning tank 11.

The cleaning tank of this kind is first of all purified water supply pipe 1.
Pure water is supplied from 2 and, for example, a hydrogen peroxide solution and an ammonium hydroxide chemical solution are supplied to the cleaning tank 11 from the chemical solution supply pipes 13 and 14, respectively, and the tank is filled with the chemical solution. Then, in the cleaning process, the chemical solution flows out from the cleaning tank 11 to the outer tank 19 and is again introduced into the cleaning tank 11 by the pump 18 so that the chemical solution is constantly renewed. Further, when the cleaning ability is deteriorated or periodically, the cleaning liquid is discharged to the outside of the cleaning tank 11 by opening the valve 20.

The chemical liquid supply piping system, the pure water supply piping system, the chemical liquid circulation piping system, and the carrier for accommodating wafers in the above-mentioned cleaning apparatus are all made of a resin material having chemical resistance, and no metal material is used. Was not done.

[0006]

In this conventional cleaning apparatus, the parts used in the chemical liquid supply and pure water supply systems and the chemical liquid circulation system are made of a porous Teflon-based material, and this resin body is often used. The material contains a metal such as aluminum or iron at the time of molding, and this is extracted into the chemical solution during cleaning. The carrier used for cleaning is also made of a Teflon-based porous material and contains these metals. Moreover, these carriers have many opportunities to be contaminated if they are exposed to the atmosphere or touched by human hands.

When the metal extracted from such a carrier or part enters the cleaning liquid, the cleaning liquid and the processing tank 11 are contaminated. When the wafer is immersed in the contaminated cleaning solution,
The metal eluted in the cleaning solution is taken into the wafer and the recombination lifetime is shortened. Furthermore, this contamination is repeatedly accumulated, and the recombination lifetime is further reduced accordingly.

It is an object of the invention to provide a cleaning device with means for removing the extracted metal which should eliminate these problems.

[0009]

A first cleaning apparatus of the present invention comprises a cleaning tank for storing a chemical solution and immersing a semiconductor substrate, a chemical solution supply pipe system section for supplying the chemical solution to the cleaning tank, and a circulation of the chemical solution. And a chemical liquid circulation piping system section, an acidic chemical solution supply piping system section for supplying an acidic chemical solution to the chemical solution supply piping system section and the cleaning tank.

The second cleaning apparatus of the present invention comprises, in addition to the first cleaning apparatus, an acidic chemical solution tank in which only a single carrier for accommodating the semiconductor substrate is immersed.

[0011]

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

FIG. 1 is a schematic sectional view showing a cleaning tank in a cleaning apparatus according to the first embodiment of the present invention. As shown in FIG. 1, the cleaning tank in this cleaning apparatus is a quartz cleaning tank 11
Has an outer washing tank 19 attached to the outside thereof. Cleaning tank 1
1, a pure water supply 12 for supplying pure water, a chemical solution supply pipe 13 for supplying hydrogen peroxide water, and a chemical solution supply pipe 14 for supplying an ammonium hydroxide solution, as well as a mixed solution of an acidic chemical solution such as hydrofluoric acid and nitric acid such as fluorine That is, the acidic chemical solution supply pipe 10 for supplying the mixed solution of acid: nitric acid = 3: 7 is provided. In addition, this acidic chemical liquid supply pipe 10 is provided with the other three supply pipes 12, 13, 1.
4 and the valves 17 are installed in each piping system.
And the filter 16 are provided independently. Further, a circulation pipe 15 for circulating the cleaning liquid is attached to the cleaning tank 11, and a pump 18 for pumping the chemical liquid from an outer tank 19 and a filter 16 for filtering the chemical liquid are connected.

In the case of cleaning a wafer in the cleaning apparatus having the above-described structure, first, before cleaning with an ammonium hydroxide solution which is an alkaline chemical solution and hydrogen peroxide solution, or after cleaning with an alkaline chemical solution at least once. That is, the washing tank 11 is washed with an acidic chemical solution. Further, the pure water and chemical solution supply pipes 12, 13 and 14 are washed with an acidic solution. That is, the metal extracted by this is washed away.

FIG. 2 is a flow chart for explaining one operation of the cleaning apparatus of FIG. Next, the preparatory operation when cleaning is performed using an alkaline chemical in this cleaning device will be described. First, in step A of FIG. 2, the alkaline solution remaining in the cleaning tank 11 is drained. The drainage is the valve 2 in FIG.
Made by opening zero. Next, in step B, pure water is supplied, and in step C, the pure water is circulated through the circulation pipe 15 shown in FIG. 1, and then, in step D, it is drained to sufficiently remove the alkaline solution. Next, in step E, the acidic chemical solution and pure water, for example, a mixed acid of hydrofluoric acid and nitric acid and pure water are mixed in a ratio of 1:10 and introduced into the cleaning tank 11. After circulating this through the circulation pipe 15 in step F, the liquid is drained in step G. Further, in step H, pure water is supplied and circulated through the circulation pipe 15 in step 1, and then drained in step J to sufficiently remove the acidic chemical solution. Next, the step K alkaline chemical liquid is supplied. By doing so, all the metal in the cleaning tank 11 will be removed.

Further, if the valves 22 and 23 are opened when the acidic chemical liquid is introduced into the cleaning tank 11, the cleaning chemical liquid supply pipe system can also be cleaned with this acidic chemical liquid.

As described above, the metal contained in the cleaning tank and the piping system is dissolved in the acidic chemical liquid and discharged. Therefore, heavy metals can be removed from all of the cleaning tank 11 cleaning solution circulation piping system and the pure water / chemical solution supply piping system. Further, the carrier may be washed in advance with another acidic chemical liquid layer. 3 (a) and 3 (b) are views showing the configuration of the cleaning apparatus according to the second embodiment of the present invention. In this cleaning device, a device for cleaning a wafer cleaning carrier with an acidic chemical liquid is added after the cleaning device for cleaning with an alkaline chemical liquid having the cleaning tank described in the above embodiment. That is, as shown in FIG. 2, an acid chemical cleaning tank 36, a shower tank 38, and a dryer 39 for cleaning the cleaning carrier 41 after the wafer transfer mechanism 35 for transferring the wafer of the cleaning carrier 41 to the carrier 42 for transportation. And the carrier transfer mechanism 40 for transferring the carrier to the transfer device 45.

FIG. 4 is a flow chart for explaining one operation of the cleaning apparatus of FIG. Next, the operation of this cleaning device is shown in FIG.
And FIG. 4 will be described. When the carrier 42 for storing the wafer shown in FIG. 3 is placed on the carrier box 43 and carried to the front of the wafer transfer mechanism 30, first, the cleaning carrier 41 is placed in the wafer transfer mechanism 30. Is set. Next, the carrier 42 for transportation is set in the wafer transfer mechanism 30. Next, the wafer in the carrier 42 is transferred to the carrier 41 for cleaning. Next, the cleaning carrier 41 is transferred to the cleaning tank 11 by a carrier (not shown). At the same time, the carrier 42 for transportation is returned into the carrier box 43, and the carrier box 43 moves in front of the wafer transfer mechanism 35. Then, through steps A, B and C shown in FIG. 4, the piping system and the cleaning tank are cleaned with an acidic chemical solution as in the above-described embodiment, and the cleaning carrier 41 containing the wafer is cleaned by the cleaning tank 11, the shower tank 32, and the cleaning tank 41. Washing tank 33 and dryer 34
After that, the wafer is transferred to the wafer transfer mechanism 35. Next, the carrier 42 in the carrier box 43 moved to the front of the wafer transfer mechanism 35 in step D is set in the wafer transfer mechanism 35. Then, the wafer in the cleaning carrier 41 is transferred to the carrying carrier 42. And the carrier 42 for transportation is the carrier box 4
Returned to 3

Next, in step E, the carrier 41 is transferred to the acidic chemical solution cleaning tank 36, where the heavy metals taken in by the carrier are removed. Next, in steps F to G, the cleaning carrier 41 is transferred to the carrier transfer mechanism 40 via the shower tank 37, the water cleaning tank 38, and the dryer 39. Next, the cleaning carrier 41 transferred to the carrier transfer mechanism 40 in step H is transferred to the transfer device 45 and transferred to the front of the wafer transfer mechanism 30. In this way, the carrier can be sequentially cleaned in advance. In this embodiment, the cleaning in the former stage is described as the cleaning with an alkaline chemical solution, but the present invention is not limited to this.

FIG. 5 is a flow chart for explaining another operation of the cleaning apparatus of FIG. This operation is an operation when the cleaning carrier is first cleaned, and is almost the same as the operation of the above-described embodiment. Referring again to FIGS. 3 and 5, first, the cleaning carrier 41 is the wafer transfer mechanism 3
First, it is set in the transport device 45 before 5. Next, the cleaning carrier 44 is transferred to the acidic chemical solution cleaning tank 46 via the wafer transfer mechanism 35, and in step A, the cleaning carrier 41.
The metal taken in is removed. After this, in steps B and C, it is sent to the carrier transfer mechanism 40 via the shower tank 37, the water washing tank 38, and the dryer 39. After being transferred to the transfer device 45, in step D, the wafer transfer mechanism 3
It is transported to the front of 0. Then, in step E, the wafer is transferred from the carrier 42 for transportation to the carrier 41 for cleaning and is cleaned with the alkaline solution in steps F to G as in the above-described embodiment. Then, in step 1, the wafer is transferred to the carrier 42 for transportation, and the cleaning carrier 41 is cleaned again in step A.

As described above, since the cleaning carrier removes the metal by the acidic solution subsequent to the cleaning of the wafer or before the cleaning of the wafer, the contamination of the alkaline solution with the metal can be suppressed.

FIG. 5 and FIG. 7 are graphs showing the results of recombination lifetime when a wafer, which is a semiconductor substrate, is cleaned by the conventional cleaning apparatus and the cleaning apparatus of the present invention. By the way, when an experiment was conducted to compare the conventional cleaning device with the cleaning device of the present invention, as shown in FIG.
What was deteriorated to ec was recovered to 25 μS when the cleaning tank and the piping system were cleaned with the acidic chemical solution. 95 μS for the carrier washed
And the value is close to the reference wafer (ideally cleaned).

Further, as shown in FIG. 7, when the wafer was housed in a carrier that had been washed and the time and the lifetime for immersing the wafer in an alkaline chemical solution were examined, it was found that the lifetime was shortened by the immersing time. did. From this, it was possible to further confirm the problems described in the prior art.

[0023]

As described above, the present invention provides an acidic chemical solution for cleaning the cleaning tank, the chemical solution supply piping system and the chemical solution circulation piping system in addition to the chemical solution supply pipe system for supplying the alkaline chemical solution for cleaning to the same cleaning tank. By supplying chemical liquid supply piping system and an acidic chemical liquid cleaning tank for cleaning the carrier that stores and cleans the wafer before cleaning the wafer, the metal extracted from the equipment used for cleaning with the alkaline chemical liquid is melted and washed away. Therefore, it is possible to obtain a cleaning device that can be cleaned without shortening the recombination lifetime.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a cleaning tank in an embodiment of a cleaning device of the present invention.

FIG. 2 is a flow chart for explaining one operation of the cleaning apparatus of FIG.

FIG. 3 is a diagram showing the configuration of another embodiment of the cleaning apparatus of the present invention.

4 is a flow chart for explaining one operation in the cleaning apparatus of FIG.

5 is a flow chart for explaining another operation of the cleaning apparatus of FIG.

FIG. 6 is a graph showing the results of lifetimes of conventional cleaning devices and cleaning devices of the present invention.

FIG. 7 is a graph showing the results of lifetimes of conventional cleaning devices and cleaning devices of the present invention.

FIG. 8 is a diagram showing a configuration of an example of a conventional cleaning device.

9 is a schematic cross-sectional view showing the cleaning tank of FIG.

[Explanation of symbols]

 10 Acidic chemical liquid supply pipe 11 Cleaning tank 12 Pure water supply pipe 13,14 Chemical liquid supply pipe 15 Circulation pipe 16 Filter 17,20,21,22,23 Valve 18 Pump 19 Outer tank 30,30a, 30b, 35 Wafer transfer mechanism 32,37 Shower tank 33,38 Wash tank 34,39 Dryer 40 Carrier transfer mechanism 41 Cleaning carrier 42 Transport carrier 43 Carrier box 45 Transport device

Claims (2)

[Claims] 1. A cleaning tank for storing a chemical solution for immersing a semiconductor substrate, a chemical solution supply piping system section for supplying the chemical solution to the cleaning tank, a chemical solution circulation piping system section for circulating the chemical solution, and the chemical solution supply piping system. And a cleaning tank, and an acidic chemical solution supply piping system section for supplying an acidic chemical solution to the cleaning tank. 2. The cleaning apparatus according to claim 1, further comprising an acidic chemical solution tank in which only a single carrier of the semiconductor substrate is immersed.