NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 1 Treatment of CMP Waste Streams B.M. Belongia, Y. Sun Dr. J.C. Baygents, Dr. S. Raghavan The University of Arizona Joe O’Sullivan Pall Corp.  1999 Arizona Board of Regents for The University of Arizona

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 2 Outline Background Treatment Strategies Electrocoagulation/Electrodecantation Studies – pH Effects & Electrode Compartments – Solid/Liquid Separation – Copper Removal Cross-flow filtration – Microza TM UF Systems Summary

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 3 Significance Large quantities of waste slurry generated from CMP –~ 6 L of waste slurry generated per wafer – % solids and ~ 40 ppm copper ions Efficient disposal or recycle strategies need to be developed to comply with environmental regulations. Recycling would require that the dilute waste slurry be concentrated to the initial slurry solids content and the particle size remain unchanged.

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 4 Slurry Types Oxide slurry –Silica is the abrasive material –Suspension is stabilized with either NH4OH or KOH; pH = –Used to polish oxide layers –Particle size: nm

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 5 Slurry Types (cont’d) Metal –Abrasive is primarily aluminum oxide, but some contain silica –Contains an oxidizer, either ferric nitirate, potassium iodate or hydrogen peroxide –pH = –Used to polish tungsten and copper (recently popular) interconnects –Particle size: nm

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 6 Why Treat CMP Wastewater? Suspended solids too high to discharge to sewer Traditional flocculation and clarification requires large tanks and lots of chemical addition A need to reclaim water at the individual facility

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 7 POLISHING TOOL RINSE WATER NEW SLURRY 6–10wt% solids WASTE SOLIDS WATER MIRACULOUS PROCESS! WATER TO POLISHING LOOP USED SLURRY 0.02–0.5wt% solids 2 –40ppm Cu

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 8 Treatment Objective e.g. a copper CMP waste may contain: 0.02 – 0.5% solids 2 – 40ppm copper ions An organic complexant (e.g. EDTA, Citric Acid) A corrosion inhibitor (e.g. BTA) To develop a generic methodology for the treatment of CMP waste streams.

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 9 Treatment Strategies 1. Electrocoagulation/Electrodecantation (EC/ED) – University of Arizona research – Possible follow on to ultrafiltration 2. Cross-flow filtration – Pall Microza TM ultrafiltration system

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 10 EC/ED Electrocoagulation –used to treat waste steams; electric field applied for a short period, suspension allowed to settle in absence of field — rate of settling was found to be enhanced Electrodecantation –used to concentration proteins, viruses, natural rubber latex, and various inorganic sols

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 11 EC/ED Apparatus Anode (+) (Stainless Steel) Cathode (-) (Stainless Steel) Membrane Sample Port Water Suspension

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 12 Electrode Reactions 2H 2 O + 2e -  H 2 + 2OH - (+) Electrode 2H 2 0  4H + + 4e - + O 2 (-) Electrode 2H + + 2e -  H 2 Suspension pH increases Membrane Water pH decreases or

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 13 Electrophoretic Mobility of Al 2 O 3 cm 2 /V·s  pH 1mM KNO 3 pH Time (min) Anode Chamber Cathode Chamber 3.5V/cm pH Changes

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 14 Initial Cond.  1300  S/cm Initial pH  V/cm  3.50V/cm  7.00V/cm 14.00V/cm Time (min) c/c 0 EC/ED of Al 2 O 3 Membrane Cathode Anode Solids Clarified Liquid (Sample Zone) Liquid Level

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 15 Copper Removal during EC/ED 1.75V/cm  3.50V/cm  7.00V/cm 14.00V/cm Time (min) c Cu /c 0Cu Initial Cond.  1300  S/cm Initial pH  6.0

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 16 Copper Distribution Membrane Cathode Plated Cu (16.3%) Anode 44ml 68.0ppm Cu (39.4%) 165 ml 4.2ppm Cu (9.7%) 97 ml 16.0ppm Cu (20.5%) Initial Suspension 34ppm Cu

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 17 Effect of EDTA and Cu on Al 2 O 3 Particle Charge Electrophoretic Mobility cm 2 /V·s  Al 2 O 3 Al 2 O ppm EDTA  Al 2 O ppm Cu + 184ppm EDTA pH Al 2 O 3 EDTA + Al 2 O 3 + Cu 2+ EDTA Cu 2+ pH 

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 18 Copper Distribution OH Membrane Cathode Anode OH Cu 2+ Cu(OH) 2 [(EDTA)Cu] - (EDTA) 2- pH  6

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 19 EC/ED of Concentrated Al 2 O 3 Wastes Time (min) c/c V/cm Initial pH  6.0 Initial Cond.  1300  S/cm c 0  12% solids Membrane Cathode Anode Solids  29% Clarified Liquid  0.5% solids

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 20 Filtration and EC/ED in Tandem Waste Solids Recirculated Suspension Cross-flow filtration Permeate Highly Concentrated Suspension Water Electrocoagulation Apparatus  Pall Corp. patented technology to treat CMP waste. 

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 21 Summary of EC/ED Method Alumina suspension can be dewatered by EC/ED. Copper can be simultaneously removed from the clarified layer. – plating out onto the cathode – in situ precipitation? pH changes are critical to the success of the EC/ED process.

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 22 Cost and Power Consumption 1.75V/cm  3.50V/cm  7.00V/cm Time (min) Work (kW·hr/l)  (Using $0.05/kW  hr) For 7.0V/cm, 90mins Cost: $0.014/l 6 l/wafer For 3.5V/cm, 90mins Cost:$0.002/l 6 l/wafer

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 23 What is Ultrafiltration?

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 24 Factors Affecting Separations SIZE DIFFUSIVITY IONIC CHARGE DENSITY

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 25 Cross Section of Microza TM Hollow Fiber Membrane Uniform outer surface skin further improves mechanical properties, facilitates design and provides extra assurance of removal efficiency Macroporous regions allow low pressure differential and enhanced flow rate. Uniform skinned membrane with narrow pore range for highly efficient separation characteristics. Dense porous layer provides exceptional mechanical strength and fiber reliability.

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 26 Microza TM UF Systems Process dilute CMP wastewater –0.02% to 0.1% total suspended solids Treat oxide, metal or mixture of waste Concentrate all suspended solids –up to 15-17% Permeate is free of suspended solids –can pretreat to remove ferric ion and soluble silica –can use as RO makeup water

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 27 Challenges of Treating CMP Wastewater Abrasive material –expect months service life on UF modules Broad pH range –oxide, metal or mixed waste –polyacrylonitrile membrane, pH 2-10 Prevention of membrane fouling –high linear velocity –reverse filtration

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 28 Portable Microza TM CMP Test System with Single 0.1 m 2 UF Module

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 29 Chemical Treatment for Removal of Soluble Silica Formation of silicate Precipitation of magnesium/iron silicate –iron silicates pH 8-9 –magnesium silicates pH

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 30 Silica Solubility vs. pH 0,,,,,,,,, Silica Solubility (mg/L) pH

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 31 Chemical Treatment for Removal of Soluble Silica (cont’d) Holding tank upstream of UF system Typical reaction time of 30 minutes SiO 2 + 2KOH SiO 3 - (silicate) + 2K + NaOH + MgCl Mg (OH) 2 Mg (OH) 2 + H 2 SiO 3 MgSiO 3 (s) + 2H 2 O Magnesium Silicate

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 32 Chemical Treatment for the Removal of Ferric Ion Form hydroxy complexes in acidic media –yellow-orange in color Neutralization results in hydrous ferric oxide –reddish-brown precipitate

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 33 Chemical Treatment for the Removal of Ferric Ion (cont’d) Caustic injection upstream of UF system Instantaneous reaction 2 Fe (H 2 O) 5 (OH) OH - Fe 2 O H 2 O yellow-orange in color hydrous ferric oxide reddish-brown precipitate

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 34 Copper CMP Waste Abrasive is primarily aluminum oxide Contains an oxidizer, typically hydrogen peroxide pH = 3 Used to polish copper interconnects particle size: nm

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 35 Treatment of Copper CMP Waste Soluble copper –Assuming 5000 wafer starts per week with five levels of copper results in 6 kg of copper per week –Classified as both metal finishing waste and semiconductor waste

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 36 Removal of Soluble Copper Precipitation of Cu(OH)2 by Addition of Caustic Removal of Copper by I/E –Conventional treatment method in Printed Circuit Board Industry and Plating Industry –Achievable Effluent Levels of < 0.1 ppm of copper –10K Gallons of Water per cubic foot of resin at a influent level of 10 ppm copper –Electrowinning of copper Precipitation of Cu(OH)2 by Addition of Caustic Removal of Copper by I/E –Conventional treatment method in Printed Circuit Board Industry and Plating Industry –Achievable Effluent Levels of < 0.1 ppm of copper –10K Gallons of Water per cubic foot of resin at a influent level of 10 ppm copper –Electrowinning of copper

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 37 Turn-key System for Treatment of Copper CMP Waste Removal of suspended solids by UF Removal of Soluble copper by I/E and possibly electrowinning Further treatment required to generate RO-ready water Removal of suspended solids by UF Removal of Soluble copper by I/E and possibly electrowinning Further treatment required to generate RO-ready water

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 38 Schematic of a Water Reclamation System from CMP Waste Slurry FILTER PRESS REVERSE OSMOSIS and/or ION EXCHANGE BUFFER TANK CONCENTRATE PRE-TREATMENT PERMEATE RECLAIMED WATER REJECT CONCENTRATION FILTRATE MICROZA UF System CMP WASTE SLURRIES from POLISHERS RECLAIMED WATER TO WASTE TREATMENT

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 39 Dewatering of UF Concentrate UF Concentrate –Maximum of 17% Total Suspended Solids Dewatering Via a Filter Press for Landfill Disposal –Treat with Fluoride Waste –Treat Separately RCRA Paint Filter Test Non-Hazardous Material pH Adjustment Addition of coagulant Addition of flocculant UF Concentrate –Maximum of 17% Total Suspended Solids Dewatering Via a Filter Press for Landfill Disposal –Treat with Fluoride Waste –Treat Separately RCRA Paint Filter Test Non-Hazardous Material pH Adjustment Addition of coagulant Addition of flocculant

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 40 Flux Profile for UF System Typical for Mixed CMP Slurry Waste

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 41 Buffered Tank Management Sized for 20 m 3 /hr of Mixed CMP Waste

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 42 Typical Microza TM CMP Waste Slurry Concentrating Installation (Single UF Module Skid)

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 43 Microza TM CMP Waste Slurry Installation (Multiple UF Module Skids)

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 44 Microza UF System Sizing Oxide CMP Waste Initial ConcVCF Percent Recovery Flowrate (GPM)# of Modules 0.1 %10X %50X %10X %10X %50X985016

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Belongia, et al 45 Microza UF System Sizing Mixed Oxide and Mixed Metal CMP Waste Initial ConcVCF Percent Recovery Flowrate (GPM) # of Modules 0.1 %10X %50X %10X %50X985021