Your SlideShare is downloading. ×
Metryx   Mass Metrology For Tsv (Icep2009)
Metryx   Mass Metrology For Tsv (Icep2009)
Metryx   Mass Metrology For Tsv (Icep2009)
Metryx   Mass Metrology For Tsv (Icep2009)
Metryx   Mass Metrology For Tsv (Icep2009)
Metryx   Mass Metrology For Tsv (Icep2009)
Metryx   Mass Metrology For Tsv (Icep2009)
Metryx   Mass Metrology For Tsv (Icep2009)
Metryx   Mass Metrology For Tsv (Icep2009)
Metryx   Mass Metrology For Tsv (Icep2009)
Metryx   Mass Metrology For Tsv (Icep2009)
Metryx   Mass Metrology For Tsv (Icep2009)
Metryx   Mass Metrology For Tsv (Icep2009)
Metryx   Mass Metrology For Tsv (Icep2009)
Metryx   Mass Metrology For Tsv (Icep2009)
Metryx   Mass Metrology For Tsv (Icep2009)
Metryx   Mass Metrology For Tsv (Icep2009)
Metryx   Mass Metrology For Tsv (Icep2009)
Metryx   Mass Metrology For Tsv (Icep2009)
Metryx   Mass Metrology For Tsv (Icep2009)
Metryx   Mass Metrology For Tsv (Icep2009)
Metryx   Mass Metrology For Tsv (Icep2009)
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×
Saving this for later? Get the SlideShare app to save on your phone or tablet. Read anywhere, anytime – even offline.
Text the download link to your phone
Standard text messaging rates apply

Metryx Mass Metrology For Tsv (Icep2009)

308

Published on

How Mass Metrology can be used for TSV monitor and SPC

How Mass Metrology can be used for TSV monitor and SPC

0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
308
On Slideshare
0
From Embeds
0
Number of Embeds
1
Actions
Shares
0
Downloads
2
Comments
0
Likes
0
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
No notes for slide

Transcript

  • 1. Characterisation of Through Silicon Via (TSV) processes utilising Mass Metrology Liam Cunnane, Adrian Kiermasz PhD, Gary Ditmer Metryx Ltd., Bristol UKMetryx Copyright © 1
  • 2. Outline Mass Metrology Principles Methodology Through-Silicon Via (TSV) Process Sequence Deep Silicon Etch & Polymer clean Oxide Liner Barrier & Seed Deposition Copper ECP & CMP SummaryMetryx Copyright © 2
  • 3. Principle of Mass Metrology Normal Distribution 0.4 Normal Distribution 0.4 0.3 density 0.3 0.2 ETCH density 0.2 0.1 0.1 0 ALD 43 45 47 49 51 53 55 57 59 61 63 0 x 43 45 47 49 51 53 55 57 59 61 63 Normal Distribution x 0.4 0.3 Normal Distribution density 0.2 0.4 ΔMass 0.1 0.3 ETCH density 0 0.2 43 45 47 49 51 53 55 57 59 61 63 x 0.1 PECVD PVD 0.4 Normal Distribution 0 43 45 47 49 51 53 x 55 57 59 61 63 0.3 Normal Distribution density 0.4 0.2 0.3 0.1 density 0.2 0 CMP 43 45 47 49 51 53 55 57 59 61 63 0.1 x 0 43 45 47 49 51 53 55 57 59 61 63 x Process Step All Microelectronic devices are manufactured through a series of process steps which add or remove material. Accurate measurement of mass change allows production monitoring or supports development in determining of a layer’s physical parameters. Mass metrology provides the advantages of On-product measurement, an atomic-level sensitivity, and total flexibility in application.Metryx Copyright © 3
  • 4. Mass ≠ Weight Weight Measurement Mass Measurement Load-cell utilising complex force measurement Real-time corrections for internal and external forces influencing measurement Unstable, irreproducible, not designed for Fully automatic wafer handling and host semiconductor measurement use communication compliantMetryx Copyright © 4
  • 5. Standard Mass error (80µg 1σ) Expressed as thickness on a 300mm wafer Detection capability: ~1Å for a dense material such as Ta (TaN) <5Å for silicon, silicon oxide / nitride. Advanced structures, with increased complexity, actually improves the sensitivity of mass metrology.Metryx Copyright © 5
  • 6. Simple Measurement Pre-Measurement STI Oxide Fill deposition M1 140000 135000 Mass change (µg) 130000 + 5% 125000 ΔM = | M1-M2 | 120000 115000 - 5% 110000 0 50 100 150 200 250 300 M2 Number Post-Measurement Mass Metrology is a non-invasive method for In-line monitoring ‘On-Product-Wafers’ Measurement, Backside Contact only Mass change is a direct representation of process performance Mass excursions outside the normal distribution represent process problemsMetryx Copyright © 6
  • 7. TSV - Process Steps TSV Etch TSV Cleaning Oxide Liner Barrier/Seed Cu Plate CMPMetryx Copyright © 7
  • 8. Through Si Via (TSV) Study 40 Two Via types were studied. RA -TSV A: near straight walled TSV TSV A TSV B B via with a AR of 5:1 DA 30 Aspect Ratio -TSV B: highly tapered via with a AR of ~35:1 Mass change characteristics 20 Mass (mg) of each via type investigated 0.0-30.0 30.0-60.0 60.0-90.0 10 90.0-120.0 120.0-150.0 150.0-180.0 TSV 180.0-210.0 A 210.0-240.0 0 240.0-270.0 0 0.5 1 1.5 2 2.5 3 Exposed Area % Via Diameter ~ 5 umMetryx Copyright © 8
  • 9. Etch Depth v Cycle time 150 Process requirements of each TSV A via type are unique. y = -0.0022x2 + 1.2293x + 0.0903 R2 = 0.9992 TSV B y = -0.0024x2 + 1.1901x + 4.7453 Via etch process change and R2 = 0.995 Depth % of POR response is compared by 100 Depth TSV A normalizing to the related Depth TSV B Process of Record (PoR). RA Rate of change in etch rate is TSV A 50 TSV B DA very similar, albeit slightly more pronounced on TSV B. 0 0 50 100 150 Etch Time % (Cycles)Metryx Copyright © 9
  • 10. Mass Loss v Cycle time Mass vs etch cycle time, more 150 TSV A clearly shows the difference in y = 0.9672x + 2.2678 behavior between TSV A & B. R2 = 0.9999 Mass Loss % of PoR TSV B y = -0.0038x2 + 1.3509x + 3.0548 TSV A exhibits a linear loss in 100 R2 = 0.9893 mass vs cycle time suggesting Mass TSV A the transport rate of species Mass TSV B and by products in and out of the Via remains constant. RA 50 TSV A TSV B DA However, in the case of TSV B, the mass loss is rapidly slowing as the feature becomes deeper. 0 0 50 100 150 Etch Time % (cycles)Metryx Copyright ©10
  • 11. Production Monitoring of Si Etch -59000 Chambers 1 & 2 are well matched -61000 Reducing Si mass loss as the wafers are processed is due to polymer loading in the chamber Mass Loss (ug) -63000 If a sudden shift of similar magnitude occurs in both -65000 chambers, it is known that this is related to incoming material -67000 Photolithography Chm 1 Chm 2 USL Target LSL Hard-mask issue -69000 1 26 51 76 101 126 151 176 Measurement NumberMetryx Copyright ©11
  • 12. Polymer Removal – Etch Chamber Sort Mass measurement of the polymer removed in the wet strip process, -300 provides a clear quantitative measurement -800 Mass Loss (ug) Chamber B is exhibits a high level -1300 of variability in mass loss during the wet clean -1800 Variability is related to the degree of polymer formed during the etch -2300 Chamber A Chamber B -2800 Stable Unstable Etch Chm Data randomized across wet clean stationsMetryx Copyright ©12
  • 13. Polymer Removal – Wet Station Sort When post etch wafers are randomized between Wet -600 More Aggressive Less Aggressive Stations #1 & #2, the same Mass Removed (ug) mass should be removed -800 Mass removed in Station #1 is greater than Station #2, indicating a more aggressive chemistry -1000 Mass offers a simple and direct method to monitor via wet cleaning -1200 and wet chemistry stability -1400 System 1 System 2 SystemMetryx Copyright ©13
  • 14. Oxide Liner – (HAR, Surface Area & Mass) 30000 Sidewall 40 nm TEOS Liner / 3 % Exposed Area Top Surface 25000 20000 Mass (ug) 15000 10000 5000 0 1:11 5:12 10:1 3 20:1 4 50:1 5 Aspect Ratio (AR) Mass of Oxide Liner over topography increases rapidly with exposed area and Aspect Ratio, as compared with the same nominal surface film thickness ITRS roadmap calls for AR values as high as 20:1 in the future.Metryx Copyright ©14
  • 15. Liner / Barrier Sidewall Coverage 11500 Liner / Barrier deposition, including sidewall coverage Barrier monitored non-destructively Liner Mass (ug) Liner Similar to the Oxide Liner, 10500 sidewall contribution of mass added increases on higher Aspect Ratio features 9500 8500 1 2 3 4 5 6 7 8 Lot No.Metryx Copyright ©15
  • 16. Developing Effective Cu-Fill with Mass Monitor Mass increase v. Top Total Mass (mg) surface thickness Fill Superior Selective bottom-up, void free fill, results in the mass increasing Voiding rapidly as compared to top surface thickness Fill Marginal If Voids are present then the Surface thickness ‘x’ mass will increase more slowly Thickness ‘xa’ Process A compared to increase in top surface thickness increase Thickness ‘ya’ Thickness ‘xb’ Process B Thickness ‘yb’ Process CMetryx Copyright ©16
  • 17. Metal Fill & CMP 20.00 Mass removed during DEP CMP reflects the mass 15.00 CMP of the Barrier & Cu Fill 10.00 This correlation of mass Mass Deviation (mg) removed to mass 5.00 deposited affirms the CMP process stability 0.00 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 -5.00 -10.00 -15.00 -20.00 Data No Data is plotted in mg deviation from targetMetryx Copyright ©17
  • 18. CMP Stability 8.00 DEP Mass (Barrier + ECP) Added Mass removed during CMP is Cu well correlated to the mass Barrier added by Barrier + ECP Liner 3.00 Therefore the CMP is observed to be well controlled. -8.00 -3.00 2.00 7.00 12.00 17.00 Where there is an undesirable -2.00 CMP under- or over-polish, CMP Mass (Barrier + ECP) scatter will be seen in the data -7.00 Removed This ‘compensation’ results in Barrier Liner a mass stability of the wafers relative to post contact etch which is excellent -12.00 y = -1.0001x + 2E-13 2 R = 0.9997 -17.00 Data is plotted in mg deviation from TargetMetryx Copyright ©18
  • 19. Mass Stability Mass variation is 15 shown relative to the mean for the group 10 Box-Whisker plots indicate the Mass 5 Mass (mg) stability relative to the previous step 0 The CMP process -5 accommodates Cu variance in the Fill -10 TSV Barrier Barrier process by adjusting Liner Liner the CMP polish -15 Final Mass Stability Final shown is relative to TSV Liner Barrier Cu ECP CMP Stability Etch the post contact etchMetryx Copyright ©19
  • 20. Mass added Post TSV CMP Mass measured post Etch and 161000 post CMP reflects the mass filling the TSV. 160000 Mass Added (ug) Process excursions related to Via Etch, Via Fill and CMP are 159000 all effectively monitored by the stability in this mass delta. 158000 Barrier 157000 TSV Liner 156000 0 20 40 60 80 100 Measurement NumberMetryx Copyright ©20
  • 21. TSV Metrology – Summary Through-Silicon Via (TSV) Etch in Silicon Measure etched silicon volume Confirms etch depth and profile meet process definition Oxide Liner Confirm step coverage of liner Barrier/Seed Accurate measurement of multi-stack layer Determine effective sidewall coverage Copper – ECD Fill and CMP Cleaning of Copper Oxide from Seed prior to ECP Optimization of Bottom Fill and Void prevention Monitor, affirm process stabilityMetryx Copyright ©21
  • 22. Metryx Copyright ©22

×