TeraDox Wet Clean Process and System Advanced Surface Preparation - PowerPoint PPT Presentation

TeraDox Wet Clean Process and System Advanced Surface Preparation HTechnology Altay, Inc. http://www.altayinc.com info@altayinc.com +1 855 717 3932

TeraDox Wet Clean Process and System What are the main factors that influence undesirable native oxide formation during and after wet processing to achieve pristine, stable, “oxide free” and ideal Si-Hx terminated silicon surfaces? Silicon wafer material and electrical specifications that affect the minority carrier lifetime & surface ➢ recombination velocity (ie. non-silicon impurities, dopants, crystallinity, defects, surface morphology) Dissolved impurities (ie. Oxygen, CO2, silica) in the oxide removal wet process chemistry, which include the ➢ DI water, HF and HCl, as well as impurities in the N2 purge and drying gas. Impurities in the wet process equipment materials and components ➢ Gaseous (ie. O2, CO2) permeation through wet processing equipment piping and materials which ➢ contaminate the wet process chemistry and environment that comes in direct contact with the wafer surfaces Wet process recipe conditions for the wet etching, rinsing and drying steps ➢ Bare silicon surface exposure to airborne contamination (ie. oxygen, moisture, CO2,organics), light and heat ➢ Queue time: the exposure time in air after the bare silicon surface has been prepared and before it placed ➢ in an inert environment (typically for the subsequent process) 2

TeraDox Wet Clean Process and System What is the TeraDox System ? An enhanced version of Altay’s NEO FRD system which integrates chemical processing, insitu -rinsing and a world class drying technology into a single vessel wet processor (“dry in / dry out”) for wafers and other substrates. This system... incorporates five patented “oxide free” methods and system features ➢ is comprised of a main wet process unit which is paired in series with a stand-alone Dox60 DI ➢ water degas unit maximizes the purity of the wet process chemistry and minimizies permeation, which are the ➢ critical parameters that are optimized for achieving the TeraDox’s superior “oxide free” process capabilities is offered with semi-automated or fully-automated wafer handling (including SMIF & FOUP), ➢ cassette & cassetteless configurations, and process vessels designed for batches of 3, 25 or 50 of 100-300mm diameter wafers. is also available in a Recirculating Filtered Etch Bath (RFEB) style version for R&D and low volume ➢ manufacturing applications. 3

TeraDox Wet Clean System Typical NEO-2000 TeraDox Main Unit Layout 4 DIMENSIONS :1350mm W - 1700mm D - 2000mm H WEIGHT : 1000kg

TeraDox Wet Clean System Typical Dox60 UPW Degas Unit Layout 5 DIMENSIONS : 900mm W - 1500mm D - 2000mm H WEIGHT : 400kg

TeraDox Wet Clean System PHOTOS OF THE PROCESS DECK STATIONS ON A TYPICAL CASSETTELESS 200mm SYSTEM WAFER TRANSFER / DRYER HOOD OVER THE PROCESS VESSEL WAFER TRANSFER / DRYER HOOD PROCESS VESSEL, CASSETTELESS WAFER CARRIER & ELEVATOR OVER THE WAFER CASSETTE DOCK 7 WAFER CASSETTE LOAD / UNLOAD DOCK

TeraDox Wet Clean System Example of an Altay 300mm TeraDox system configuration with FOUPS & additional cleans Dox60 DI water degas unit Degassed DI water Exhaust Space Electric Electric Changer Area TeraDox Area & Aligner Additional Additional Process QDR Wafers Chemical Chemical Bath Bath Bath Robot Robot Monitor FOUP FOUP 7

Altay TeraDox Wet Clean System Dox 60 UPW Degas Unit … it starts with purifying the water to PPT quality Stand-alone UPW treatment unit that can be installed remotely and easily interfaces with any wet ➢ processing tool Utilizes membrane contactor technology (combination of vacuum and N2 gas sweep) to degas UPW ➢ Reduces dissolved O2 as well as other gases, TOC, metals and colloidal solids like silica ➢ Achieves > 99.999% dissolved oxygen removal efficiency ➢ Capable of providing UPW with <100ppt Dissolved Oxygen (DO) for up to 60 lpm of DI water ➢ These UPW degassing capabilities aid to prevent : watermarks and allows for wafer drying without IPA on bare silicon surfaces ➢ surface roughening / faceting on bare silicon surfaces ➢ corrosion ➢ bacterial growth in the UPW supply ➢ 8

Altay TeraDox Wet Clean System Additional System Features and Options Anti-scrap features to prevent wafer breakage ➢ HCl and NH4OH (option) chemical supply network to complement the HF ➢ Chemical degassing using membrane contactor technology ➢ Fully integrated filtration and purification of the DI water and N2 ➢ Heated N2 wafer drying to minimize organic residues on the wafer surface ➢ Ionizer for the neutralization of electrostatic charge on the wafer surface (option) ➢ PdM module for reducing H2O2 to < 1ppb (option) ➢ TeraZone UHP DIO3 module (option) ➢ Mini-bulk chemical delivery module for chemical supplies (option) ➢ Mini-batch TeraDox system for 300mm wafers (alternative to full batch system) ➢ 9

TeraDox Wet Clean System Competitor WET Cleaning System & Process Flow Chemical Required Typical Full WET Clean Sequence DI Water SPM ** H2SO4 or QDR DHF/ QDR APM QDR SOM DHCL HF HCL NH4OH H2O2 DHF/ O3 DRY QDR QDR HPM DHCL N2 For Hydro Phobic Surface Only IPA DIW ** DHF and/or DHCL are used based on surface to be Cleaned 10

TeraDox Wet Clean System Apet FRD with Options (Degas, DIO3, dHF, dHCL) Full WET Clean Sequence * dHF/ DIO3 QDR QDR dHCL Dryer Dome DRY QDR DIO3 N2, IPA For Hydrophilic Surface Only Process Vessel O3 Gas Supply H2 H3 H1 DIO3 Mixer UPW UPW Chemical Required Supply Degas Fill ---------------- DI Water CHEM HF Degas HCL O3(g) HF Supply N2(g) IPA Drain HCL Supply 11 * DHF and/or DHCL are used base on surface to be cleaned (Si, SiGe, Ge)

Understanding Oxide Thickness, Monolayers and encapsulated SIMS Areal Oxide Density (AOD) when assessing “oxide free” surface preparation capabilities Assume the silicon wafer surface is terminated with either SiOx or SiHx species SiOx SiOx SIMS AOD SiOx / SiHx Description Thickness( Å ) Monolayers (atom/cm2) Coverage (%) 1 0.29 2.10E+14 29% / 71% Reference 3.5 1.0 7.20E+14 100% / 0% Typical Native Oxide 7 2.0 1.50E+15 100% / 0% Detection Limit of XPS 0.1 0.029 2.10E+13 2.9% / 97.1% Detection Limit of SIMS 0.0005 0.00014 1.00E+11 0.014% / 99.986% TeraDOx + 650C NB Si cap Non-detectable <0.00014 <1.00E+11 <0.014% / 99.986% ES Oxygen Hydrogen 3.5 Å SiOx 1 Å SiOx 0.014 Å SiOx Wafer surface 100% Typical HF Last process Encapsulated SIMS DL covered by 29% Oxygen 0.014% Oxygen 1 monolayer of Oxygen 71% Hydrogen 99.986% Hydrogen 12

TeraDox Wet Clean Process Study to measure the effect of Dissolved Oxygen concentration in the UPW of the TeraDox “oxide free” process vs. areal oxygen density (AOD) using the encapsulated SIMS method (2009) ➢ Si wafers are prepared using the TeraDox wet clean process to remove the native oxide with the UPW supply DO degassed to 1 ppb and 0.1 ppb. An unprocessed control wafer is included in the test plan as a reference for the ➢ initial native oxide on the wafers being wet cleaned. ➢ The front surface of the three wafers are encapsulated by depositing a thin (80- 150nm) silicon layer using the standardized “ASM 650 No Bake SiH4 deposition” recipe in an ASM E2000 epi reactor. ➢ Dynamic SIMS characterization is used to measure the Areal Oxygen Density (AOD), which has the units of atoms/ cm^2, at the Si cap /Si wafer interface. ➢ The AOD data also quantifies the effect of the DO in the wet clean UPW on the efficiency of the oxide removal process . 13

TeraDox Wet Clean Process Results for the effect of DO concentration in the UPW vs. encapsulated SIMS AOD unprocessed control DO= 1 ppb DO= 0.1 ppb * 7.267 E15 at/cm2 2.078 E13 at/cm2 2.627 E12 at/cm2 … as it can be seen, a lower DO in the UPW allows for a lower AOD * The detection limit of this DO meter was O.1ppb (current DO meters can now detect down to 10 ppt) 14

TeraDox Wet Clean Process Customer T’s demo: encapsulated SIMS results using the “ASM 650 No Bake SiH4 deposition” recipe (2010) ➢ Slides 16 & 17 show encapsulated SIMS profiles for three 200mm wafers using the Altay TeraDox (batch wet processor) dHF last wet clean - the wafers were dried with heated N2 only (no IPA) - oxygen peaks were non-detectable (< 1 E11 at/cm^2) on all three wafers for the center and edge ➢ Slide 18 shows encapsulated SIMS profiles for two 200mm wafers using customer T’s process of record dHF last wet clean on a DNS single wafer wet processor. - oxygen peaks > 1 E13 at/cm^2 - edge AOD ~3x higher than the center Note : A significant number of process and hardware improvements have been made on the Altay TeraDox since this demo that provide even lower O and C contamination. 15