Analytical Action To Ensure Water Availability in Semiconductor Manufacturing

WHITE PAPER Semiconductor Water Recycling: Analytical Action to Ensure Consistent Water Availability Introduction As the demand for semiconductors increases, Fabs will rely on higher quantities of water for processing. Semiconductor manufacturing utilizes an incredible amount of water, for instance, a single 200-mm or 8-inch wafer can require over 5,600 liters or 2,000 gallons of water.1 Water usage is also being driven by the need for more complex semiconductors, as the more layers used to manufacture these complex wafers, the more washes are needed to process them.1 Thus, more advanced logic circuits will require even more water to manufacture compared to past semiconductors. Changing climate conditions are increasing temperatures, leading to more frequent drought conditions. Draught formation is exacerbating an already strained water allocation issue for semiconductor companies. For example, Taiwan is experiencing water issues in Tainan, Kaohsiung, Taichung, and Hsinchu.1 The United States has decided to increase its semiconductor manufacturing and has several major semiconductors companies, such as TSMC and Intel, building Fabs in Arizona.1 The dry, arid conditions of Arizona and the limited water sources available will require US manufacturers to place an added emphasis on water allocation strategies. The Fabs that do have favorable access to water sources still must consider the environmental toll of substantial water resource removal for semiconductor processing. The balance of heavy water usage between agriculture and semiconductor manufacturing adds further strain on the water availability for these Fabs.1 Thus, water recycling is a critical factor in the viability of longterm semiconductor manufacturing. This whitepaper will examine the trends and innovations in water usage and recycling within the semiconductor industry. Water Usage Demand Increases in Semiconductor Applications.Semiconductor usage continues to grow in a number of consumer, commercial, and industrial products. This expansion is projected to increase in the future along with the complexity of the chips.2 Some of the applications of semiconductors include:  Personal electronic devices such as computers and tablets, mobile phones, and smartwatches2  Household items such as televisions, appliances, LED light bulbs, and heating/cooling equipment2  Commercial and industrial products such as lasers, optical sensors, solar batteries, medical diagnostic equipment, traffic lights, and industrial machinery2 Semiconductor Water Recycling: Analytical Action to Ensure Consistent Water Availability www.perkinelmer.com 2 Semiconductor Production Semiconductor production has a design and fabrication phase, where companies that focus solely on design are known as fabless firms and companies that focus only on fabrication are called foundries. Companies that do both the design and the fabrication are called Integrated Device Manufacturers (IDMs).2 An overview of the semiconductor production process includes:  Silicon extraction from raw material  Purification  Cylindrical ingot formation, from one to nearly 18 inches (450 mm) in diameter, up to 200 pounds each  Semiconductor design  Process engineering  Raw and fabrication materials selection  Quality control (QC) program design  Ingots are sliced into 1 mm-thick discs or “blank wafers”  Wafer diameter is adjusted if needed  Multiple layers of transistors and wiring are formed on the wafer surface in an iterative process  Steps include cleaning, oxidationdiffusion, deposition, photoresist patterning, etching, ion implantation  Wafer is cut into individual semiconductor units called dies  Semiconductor chip packaging  Each finished chip is attached to and encased in protective housing Raw Material Processing Research and Development (R&D) Blank Wafer Production Wafer Processing Wafer Cutting Cleaning Oxidation and Diffusion Deposition Photoresist Patterning Inspection and Metrology Etching Ion Implantation Figure 1. Steps of the circuit information process are repeated to build a multi-layered IC. These key steps are composed of 400 to 600 detailed steps that are typically completed over one to two months. Figure 1 outlines the steps of the circuit formation process that are repeated to manufacture a multi-layered integrated circuits. Semiconductor Water Processing and Contaminants The majority of water used in semiconductor manufacturing is used in washing and wet cleaning steps, where ultrapure water is utilized. Raw water sources are brought into a variety of processing steps to achieve ultrapure filtration. The processing of raw water removes contaminants that can affect the wafer’s functionality. As semiconductor’s become more efficient at smaller scales, they will also become more vulnerable to interferences via chemical and particulate contaminants.2 Therefore, manufacturers need technological support to detect ultra-trace levels of contaminants through the fabricating process. As the industry continues to trend to smaller and more advanced semiconductor products, detecting chemical contaminants at the parts per trillion (ppt) level is no longer adequate, with levels as low as parts per quadrillion (ppq) detection limits needing to be analyzed.1,2 As wafer complexity increases for more complex performance, the number of layers will increase in manufacturing. Each layer requires water washing during processing, thus the more layers there are the more ultrapure water will be needed.2 Semiconductor Water Recycling: Analytical Action to Ensure Consistent Water Availability www.perkinelmer.com 3 Treating Wastewater The immense water utilization steps of semiconductor manufacturing generate a lot of wastewater, which typically requires post-utilization treatment.3 The diversity of wastewater created, which is dependent on the specific application of manufacturing, requires different treatment protocols that utilize technologies that range in cost. For example, UV light is relatively cheap on an industrial scale while other treatments, such as reverse electrodialysis, are much more costly. Large foundries separate the streams and each wastewater stream has its own specific treatment depending on the chemicals and contaminants collected during manufacturing. Of this treated water output, a portion is reusable and can be put back into the system to generate more ultrapure water.3 The water that is not reusable is often stored in cooling towers where it is used to help maintain temperatures.3 Semiconductor manufacturing process wastes can generate a variety of wastewater streams and the stream’s contaminant profile is dependent on the materials and processes being used at that particular facility.3 Analytical assessment of discharged process wastewater must be subject to periodic sampling and analysis prior to its transfer to a treatment facility.3 Therefore, the characterization, storage, and transport of this waste must adhere to requirements set forth by local, state, and federal authorities.3 The waste treatment and disposal facilities require analytical data on the content of each unique waste stream to ensure compliance. Figure 2 shows the semiconductor water production overview. Water Recycling Due to the complexity and price of implementation of water recycling capabilities, smaller semiconductor companies have been slower to adopt its use. However, Large FABS, such as TSMC, Samsung, and Intel, must implement these water reuse and recycling technologies due to their large water requirements.3 In 2019, TSMC fabs in Tainan alone consumed 50,000 metric tons or 50 million liters of water per day.3 Sourcing this amount of water is not only an industrial challenge but an environmental obstacle as well. The Nanhua and Zengwen reservoirs are where the TSMC fabs were drawing water from, and their capacity dropped to significantly low levels.3 This environmental challenge is exacerbated further as Southern Taiwan is also its agricultural region and primary food developer.3 In order to continue extracting water, fabs have had to enhance their water draw and usage capabilities in the form of water recycling optimization and rainwater collection systems.3 Additionally, fabs are placing added environmental protection procedures that utilize advanced filtrations systems including:  Reverse osmosis filtration  Hollow fiber ultra-filtration  Sand filtration Feed Water RO Blend Water Water Product Water Reclaim Tank Facilities Operations Wastewater Treatment Semiconductor Factory (Fab) Incoming Raw Water Non-UPW Process Water UPW Recycle Central Scrubbers, Cooling Towers, Irrigation Evaporation (Cooling Towers) Sanitary Wastewater To Final Outfall Wastewater Fab Recycle Water Reclaim Water Wastewater Irrigation Portable Water UPW Plant POU Scrubbers, Humidification UPW Supply UPW Return Figure 2. Semiconductor water production overview. Semiconductor Water Recycling: Analytical Action to Ensure Consistent Water Availability www.perkinelmer.com 4 Why Water Purity Matters Ultrapure water (UPW) is critical in the production of semiconductor devices as it is utilized in most of the wet processing steps, including wafer-rinsing and the dilution of compounds used in chemical baths. During wet processing, contaminants from the chemical baths and the rinsing water waste can be adsorbed and precipitated onto the silicon surface via several chemical and electrochemical reactions.3 The nano-metallic particles present in the critical areas of the finished product can change the electrical parameters of the components of an integrated circuit, leading to failed electrical tests.3 If particles land on the photoresist during the lithography phase a projection error can occur on the wafer.3 Additionally, contamination can contribute to static shocks that can affect the wafer’s design.3 All of the damages resulting from these contaminants impact wafer yield and production efficiency. Thus, water purity is critical in semiconductor processing to mitigate contamination exposure to the wafer and electrical short-circuiting. Impurities are classified into the following categories:  Particles  Bacteria  Total Organic Carbons  Silica  Metals and Ions  Gases Purity Standards The purity standards for ultrapure water have dramatically over the last two decades. Today, the standards are even more stringent and as the standards continue to tighten up on contamination levels, ultrapure water processing will need to rely on advanced analytical and filtration technologies. Semiconductor Equipment and Materials International (SEMI) and the American Society for Testing and Materials International (ASTM International) have demonstrated increasingly more stringent standards in ultrapure water analysis. In SEMI F63-0918 "Guide for Ultrapure Water used in semiconductor processing”, the target values for 26 metallic contaminants are less than 1 ppt with the exception of boron (50 ppt) and nickel (3 ppt).4 The reported method detection limits (MDLs), show values of 0.5 ppt for all elements, with the exception of born (15 ppt) and nickel (1.6 ppt).4 Inductively coupled plasma mass spectrometry (ICP-MS) is the only technology that can accurately determine this collection of elements at such low levels and in a short period of time. Elemental Impurity Analysis with ICP-MS With the addition of increasingly stringent contaminant monitoring in semiconductor water recycling operations, ICP-MS systems are embracing multi-quadrupole technology with triple quadruple technology, i.e., PerkinElmer’s NexION 5000.  Novel Triple Cone Interface (TCI) with OmniRing™ technology provides outstanding sensitivity  Plasma Generator  The balanced and free-running RF generator design delivers improved robustness, high efficiency, wide power range and ensures fast power-switching between Cold and Hot Plasma modes.  LumiCoil™ RF coil is passively cooled by the extraction (not requiring water or gas cooling), so is maintenance-free, eliminating the need to replace plasma load coils  Multi-Mode Methods  Takes advantage of these technologies in combination with a cell-based Reaction mode (in the Universal Cell) and multi-quadrupole technology, yielding superior polyatomic interference removal that can further improve detection limits (DLs) and background equivalent concentrations (BECs).  Quadrupole Universal Cell  Unlike passive cells, such as octopoles and hexapoles, the Universal Cell is a quadrupole; therefore, it has the ability to control the reaction chemistry through the implementation of the rejection parameter “q”. This parameter is able to prevent byproducts of the original reaction from forming new interferences with any water vapor residues or cell gas impurities which may have been introduced into the cell.  Four Gas Channel Configuration  With four gas channels available, up to four gases can be used in the same method, delivering ultimate flexibility in the removal of any particular interference. The following ICP-MS considerations are designed to enhance analytical performance, sensitivity of the instrument, and reliability: Semiconductor Water Recycling: Analytical Action to Ensure Consistent Water Availability www.perkinelmer.com 5 Multi quadrupole technology makes interference removal by chemical reactions and Mass Shift mode even more effective since the first transmission quadrupole (Q1) set at < 0.7 amu resolution does not allow other species than those at the analyte mass to be transmitted further. This operation effectively cleans the ion beam and the background before it enters the cell. The Universal Cell (Q2), via gas reactions, deals with spectral interferences and then the analyzing quadrupole (Q3), also set at < 0.7 amu resolution, rejects products other than an analyte of interest.4 Scans shown in Figures 3 and 4 explain in detail how Reaction mode with multi-quadrupole technology works. In Figure 2, there is a Q3 scan (Single Quad mode) of a 100 ppt multi-element standard from mass 75 to 92 while O2 was introduced into the Universal Cell. The Q1 quadrupole acts as an ion guide transmitting all masses. The analyzed standard is a mixture of 50 elements including Ge, Zr and diluted HCl. Multiple peaks from the components of this standard are displayed and a peak formed by AsO+ is present at mass 91.4 The same mixed-element standard solution was scanned in Product Ion Scan mode with O2 (Figure 4), with Q1 set to 0.7 amu resolution at mass 75 instead of transmitting all ions. The plot shows a clean background with only two peaks - Co0+ and ArCl- at mass 75 and as seen as AsO- at mass 91. Consequently, arsenic is measured in the Mass Shift mode after the reaction with O2 without having to worry about potential interferences from Ge, Zr, and Cl.4 Figure 3. Q3 scan (Single Quad) of a 100-pt mixed-element standard from mass 75 to 92. Figure 4. MS/MS scan of a 100-ppt mixed element standard from mass 75 to 92 while Q1 transmits only ions at mass 75. P u l s e I n t e n s i t y P u l s e I n t e n s i t y Semiconductor Water Recycling: Analytical Action to Ensure Consistent Water Availability www.perkinelmer.com 6 Using MS/MS and Mass Shift modes with reaction gases (Reaction mode) and without reaction gases (Standard mode), DLs and BECs were measured for 50 elements in ultrapure water. This analysis used hot plasma conditions and a onesecond integration time per isotope.4 Table 1 shows the results of 26 semiconductor-essential elements. Detection limits in Hot Plasma mode for all 26 essential elements for the semiconductor industry were found to have concentrations lower than 0.3 ppt, easily fulfilling the 1-ppt requirement by SEMI or ASTM standards. BECs for most of the elements were found to be less than 0.5 ppt, demonstrating the effectiveness of the gas reactions and the MS/MS modes in removing spectral interferences.4 In Table 2, DLs and BECs for an additional 24 elements are shown with similarly low values for both parameters. For the BEC and DL measurements, calibration curves were established with 10, 20, 40, and 60 ppt standards. All curves had linear regression values (r2)> 0.999, demonstrating the linearity of the analysis, the ability to accurately measure at low concentrations, and the effectiveness of the interference removal.4 Element Mode Isotope Selection (Q1/Q3) DLs BECs Li Standard 7/7 0.028 0.018 B Standard 11/11 0.178 0.239 Na Standard 23/23 0.091 0.108 Mg Standard 24/24 0.028 0.026 Al Reaction Ammonia 27/27 0.049 0.180 K Reaction Ammonia 39/39 0.158 0.459 Ca Reaction Ammonia 40/40 0.085 0.412 Ti Reaction Oxygen 48/64 0.033 0.007 V Reaction Ammonia 51/51 0.009 0.004 Cr Reaction Ammonia 52/52 0.081 0.340 Mn Reaction Ammonia 55/55 0.055 0.015 Fe Reaction Ammonia 56/56 0.173 0.915 Co Reaction Ammonia 59/59 0.017 0.026 Ni Reaction Ammonia 60/60 0.271 0.433 Cu Reaction Ammonia 63/63 0.030 0.081 Zn Reaction Ammonia 66/66 0.085 0.126 As Reaction Oxygen 75/91 0.109 0.045 Sr Standard 88/88 0.007 0.008 Mo Reaction Ammonia 98/98 0.038 0.033 Cd Standard 114/114 0.058 0.027 Sn Standard 118/118 0.075 0.012 Sb Standard 121/121 0.050 0.077 Ba Standard 138/138 0.014 0.012 W Standard 184/184 0.053 0.042 Pt Standard 195/195 0.268 0.271 Pb Standard 208/208 0.031 0.014 Table 1. UPW DLs and BECs in ppt for 26 essential elements for the semiconductor industry measured in Hot Plasma mode. Element Mode Isotope Selection (Q1/Q3) DLs BECs Be Standard 9/9 0.116 0.060 Si Reaction Hydrogen+Ammonia 28/28 25.9 446.8 P Reaction Oxygen 31/47 2.86 1.39 S Reaction Oxygen 32/48 8.7 195.1 Sc Reaction Oxygen 45/61 0.022 0.008 Ga Standard 69/69 0.014 0.007 Ge Reaction Ammonia 74/74 0.071 0.294 Se Reaction Oxygen 78/94 1.160 0.652 Nb Standard 93/93 0.015 0.012 Ru Standard 102/102 0.040 0.097 Rh Standard 103/103 0.162 0.073 Pd Standard 106/106 0.055 0.033 Ag Standard 107/107 0.107 0.064 In Standard 115/115 0.014 0.008 Te Standard 130/130 0.057 0.070 Hf Standard 180/180 0.017 0.025 Ta Standard 181/181 0.006 0.010 Re Standard 187/187 0.045 0.017 Ir Standard 193/193 0.047 0.587 Au Standard 197/197 0.062 0.103 Tl Standard 205/205 0.017 0.007 Bi Standard 209/209 0.004 0.011 Th Standard 232/232 0.028 0.016 U Standard 238/238 0.016 0.019 Table 2.UPW DLs and BECs in ppt for non-essential elements for the semiconductor industry measured in Hot Plasma mode. Semiconductor Water Recycling: Analytical Action to Ensure Consistent Water Availability For a complete listing of our global offices, visit www.perkinelmer.com/ContactUs Copyright ©2024, PerkinElmer U.S. LLC. All rights reserved. PerkinElmer® is a registered trademark of PerkinElmer U.S. LLC. All other trademarks are the property of their respective owners. 105079 PerkinElmer U.S. LLC 710 Bridgeport Ave. Shelton, CT 06484-4794 USA (+1) 855-726-9377 www.perkinelmer.com Cold Plasma mode, in conjunction with MS/MS, is able to obtain extremely low DLs and BECs in Standard and Reaction (NH3) modes for a few elements that have Ar-based interferences or whose sensitivity is enhanced by the reduction of Ar ions in the plasma stream as outlined in Table 3.4 Thus, advanced multi-quadrupole ICP-MS systems, such as the NexION 5000, that contain optimized sample introduction systems, load coils, 34-MHz RF plasma generators, and a universal cell with four gases should be a key consideration in semiconductor processing facilities. The Future of Water Recycling in Semiconductor Manufacturing Increased semiconductor demand in both volume and complexity and global warming trends will continue to expand the amount of water recycling necessary to remain viable in the semiconductor industry. To compound this issue further, water recycling operations will face more stringent standards and will require the use of advanced analytical technologies to meet these expectations. By utilizing the latest innovations in ICP-MS technology, manufacturers can leverage the most sensitive and robust analytical systems to meet these standards and optimize their water recycling strategies. Those that adapt to this evolving semiconductor landscape by incorporating these analytical systems and rise to this water challenge will not only ensure their viability but will help ensure the industry moves in a more sustainable direction. References 1. The Big Semiconductor Water Problem. 2022. Asianometry. https://www.asianometry.com/p/the-big-semiconductorwater- problem#:~:text=It%20takes%20about%206%2C000%20 liters%20or%201%2C600%20gallons,5%2C600%20liters%20 or%202%2C000%20gallons%20of%20ultrapure%20water. 2. Semiconductor Whitepaper. PerkinElmer. 2020. https://pki. showpad.biz/webapp2/content/channels/ad1090a5ba40efa83 71b8625f5573852/682b82d11146d770a900d495ff630daa577 b68be8621659a82a719bb8c55928/f682b82d11146d770a900d 495ff630daecf4165fa73c55ede52e77401b0ea5ae?page=5. Element Mode Isotope Selection (Q1/Q3) DLs BECs Li Standard Cold 7/7 0.0004 0.0001 Na Standard Cold 23/23 0.033 0.045 Mg Standard Cold 24/24 0.008 0.004 Al Reaction Cold Ammonia 27/27 0.012 0.005 K Reaction Cold Ammonia 39/39 0.030 0.021 Ca Reaction Cold Ammonia 40/40 0.025 0.050 Cr Reaction Cold Ammonia 52/52 0.011 0.020 Mn Reaction Cold Ammonia 55/55 0.006 0.003 Fe Reaction Cold Ammonia 56/56 0.009 0.052 Co Reaction Cold Ammonia 59/59 0.008 0.003 Ni Reaction Cold Ammonia 60/60 0.029 0.017 Cu Reaction Cold Ammonia 63/63 0.010 0.012 Table 3. UPW DLs and BECs in ppt measured in Cold Plasma mode. 3. The Purest Water in the World. Jon, Y. 2022. Asianometry. https://www.asianometry.com/p/the-purest-water-in-theworld#:~: text=Fabs%20use%20ultrapure%20water%20 to%20rinse%20wafer%20surfaces%2C,water%20each%20 minute%2C%202-3%20million%20gallons%20each%20day. 4. Characterization of Ultrapure Water Using NexION 5000 ICP-MS. PerkinElmer. 2020. Waltham, MA.