Etching solution recycling system and method for wafer etching apparatus

Patent metadata

Field	Value
Publication number	US-11229856-B2
Application number	US-201715719610-A
Country	US
Kind code	B2
Filing date	Sep 29, 2017
Priority date	Sep 29, 2017
Publication date	Jan 25, 2022
Grant date	Jan 25, 2022

Abstract

An etching solution recycling system for a wafer etching apparatus is provided. The etching solution recycling system includes a settling tank, a seed provider, and a fluid control unit. The settling tank is connected to an etching tank of the wafer etching apparatus and configured to receive an etching solution from the etching tank. The seed provider is configured to provide at least one seed crystal into the settling tank to reduce the silicate concentration in the etching solution in the settling tank. The fluid control unit is configured to deliver the etching solution in the settling tank back into the etching tank.

First claim

What is claimed is:

1. An etching solution recycling system for a wafer etching apparatus, comprising:
an advanced process control (APC) system;
a settling tank connected to an etching tank of the wafer etching apparatus and configured to receive an etching solution from the etching tank;
a silicate concentration monitoring system coupled to the settling tank and the APC system, configured to detect a silicate concentration in the etching solution in the settling tank and send a detected data related to the silicate concentration to the APC system;
a seed provider configured to provide at least one seed crystal into the settling tank to reduce the silicate concentration in the etching solution in the settling tank and to remove the at least one seed crystal from the settling tank, wherein the seed provider includes a rope connected to the at least one seed crystal, and wherein the APC system is configured to control the rope to move downwardly to place the at least one seed crystal into the settling tank and to control the rope to move upwardly to pull one of the at least one seed crystal out of the settling tank in response to the detected data from the silicate concentration monitoring system; and
a fluid control unit configured to deliver the etching solution in the settling tank back into the etching tank.

2. The etching solution recycling system as claimed in claim 1 , further comprising a cooler configured to cool the etching solution that is delivered to the settling tank from the etching tank.

3. The etching solution recycling system as claimed in claim 1 , further comprising a heater configured to heat the etching solution that is delivered to the etching tank from the settling tank.

4. The etching solution recycling system as claimed in claim 1 , wherein the seed provider provides seed crystals several times to increase a rate of decrease in silicate concentration in the etching solution in the settling tank.

5. The etching solution recycling system as claimed in claim 1 , further comprising a filter removably provided in the settling tank for collecting the at least one seed crystal.

6. The etching solution recycling system as claimed in claim 1 , further comprising a filter connected to the etching tank and the settling tank and configured to filter the etching solution that is delivered to the etching tank from the settling tank.

7. The etching solution recycling system as claimed in claim 1 , further comprising a plurality of settling tanks, and the seed provider is configured to provide the at least one seed crystal into at least one of the settling tanks.

8. The etching solution recycling system as claimed in claim 1 , further comprising a plurality of recirculation loops, and the settling tank and the fluid control unit are provided in at least one of the recirculation loops.

9. The etching solution recycling system as claimed in claim 1 , further comprising:
a first recirculation loop comprising a first filter and a first heater, wherein the first filter is connected to the etching tank, and the first heater is connected to the first filter and the etching tank; and
a second recirculation loop comprising the settling tank, a second filter, and a second heater, wherein the second filter is connected to the settling tank, and the second heater is connected to the second filter and the etching tank.

10. The etching solution recycling system as claimed in claim 1 , wherein the etching solution comprises phosphoric acid.

11. A wafer etching apparatus, comprising:
an advanced process control (APC) system;
an etching tank configured to contain an etching solution;
a settling tank configured to receive the etching solution from the etching tank;
a silicate concentration monitoring system coupled to the settling tank and the APC system, configured to detect a silicate concentration in the etching solution in the settling tank and send a detected data related to the silicate concentration to the APC system;
a seed provider configured to provide at least one seed crystal into the settling tank to reduce the silicate concentration in the etching solution in the settling tank and to remove the at least one seed crystal from the settling tank, wherein the seed provider includes a rope connected to the at least one seed crystal, and wherein the APC system is configured to control the rope to move downwardly to place the at least one seed crystal into the settling tank and to control the rope to move upwardly to pull one of the at least one seed crystal out of the settling tank in response to the detected data from the silicate concentration monitoring system; and
a fluid control unit configured to deliver the etching solution in the settling tank back into the etching tank.

12. The wafer etching apparatus as claimed in claim 11 , further comprising a cooler configured to cool the etching solution that is delivered to the settling tank from the etching tank, and further comprising a heater configured to heat the etching solution that is delivered to the etching tank from the settling tank.

13. A wafer etching apparatus, comprising:
an advanced process control (APC) system;
an etching tank configured to contain an etching solution;
a first silicate concentration monitoring system coupled to the etching tank, configured to measure a silicate concentration in the etching solution in the etching tank;
a settling tank configured to receive the etching solution from the etching tank;
a second silicate concentration monitoring system coupled to the settling tank and the APC system, configured to detect the silicate concentration in the etching solution in the settling tank and send a detected data related to the silicate concentration in the etching solution in the settling tank to the APC system;
a seed provider comprising a rope connected to a seed crystal, wherein the APC system is configured to control the rope to move downwardly to place the seed crystal into the settling tank and to control the rope to move upwardly to pull the seed crystal out of the settling tank in response to the detected data from the second silicate concentration monitoring system; and
a connection line configured to allow the etching solution in the settling tank to flow back to the etching tank.

14. The wafer etching apparatus as claimed in claim 13 , further comprising a cooler configured to cool the etching solution that is delivered to the settling tank from the etching tank.

15. The wafer etching apparatus as claimed in claim 13 , wherein the etching solution comprises phosphoric acid, and the seed crystal comprises a mono-crystalline silicon seed.

16. The wafer etching apparatus as claimed in claim 13 , further comprising:
a first recirculation loop comprising a first filter and a first heater, wherein the first filter is connected to the etching tank, and the first heater is connected to the first filter and the etching tank; and
a second recirculation loop comprising the settling tank, a second filter, and a second heater, wherein the second filter is connected to the settling tank, and the second heater is connected to the second filter and the etching tank.

17. The wafer etching apparatus as claimed in claim 16 , wherein the second recirculation loop further comprises a cooler configured to cool the etching solution that is delivered to the settling tank from the etching tank.

18. The wafer etching apparatus as claimed in claim 11 , further comprising:
a first recirculation loop including a recirculation line and a first filter, wherein both ends of the

Assignees

• Taiwan Semiconductor Mfg Co Ltd

Inventors

• Fan Che-Lun

Classifications

• H10P72/0426

  with the semiconductor substrates being dipped in baths or vessels · CPC title

• H10P72/0402

  Apparatus for fluid treatment (H10P72/0441, H10P72/0448 take precedence) · CPC title

• B01D21/305

  Control of chemical properties of a component, e.g. control of pH · CPC title

• B01D9/0077

  Screening for crystallisation conditions or for crystal forms · CPC title

• B01D9/005

  Selection of auxiliary, e.g. for control of crystallisation nuclei, of crystal growth, of adherence to walls; Arrangements for introduction thereof · CPC title