Integrated circuits using 2.5D advanced packaging are shipping. 3D packaging with thru-silicon vias (TSV) has been demonstrated. “5.5D” packages may not be far behind. Probe card suppliers have made progress building interconnect technology for the micro-bump arrays. Standards committees have started defining IC interface standards and test access protocols.
But what does the Test Engineer and Management really want? What can they afford? What are the most likely scenarios? Factors that determine which test technology can support the desired test flow are examined. In particular, probe card technology for probing TSV bumps and potential usage models are reviewed.
Rob Marcelis (BE Precision Technology ‐ The Netherlands), “H3D Profiler for Contact Less Probe‐Card Inspection”:
Probe cards require inspection since they are consumables subject to wear. Changes in probe position or shape can damage the semiconductor devices they are testing. As probe cards increase in size and probe count, the probe cards themselves are becoming more expensive to test in terms of test time and complexity. Each new test system typically requires an expensive “motherboard” for the probe card metrology tool to simulate the mechanics of the tester and provide electrical interconnect to the card for electrical testing.
Jose Horas (Intel Mobile Communications ‐ Germany), “28nm Mobile SoC Copper Pillar Probing Study”:
Intel Mobile Communications (IMC, previously Infineon Wireless) has started to switch from tin-silver (SnAg) solder bumps to copper pillars (CuP) with SnAg caps for attaching their die to packages. Since the bumps and pillars are formed on the wafer prior to testing of the devices the wafer probe process must accommodate both. CuP offer several advantages over SnAg bumps: tighter pitch (now at 120 µm and able to scale smaller versus 150 µm for SnAg bumps), lower substrate costs due to relaxed design rules, and lower assembly costs (easier to under fill).
As the number of probes on probe cards increase due to greater parallelism, driven by the desire for one touchdown testing and the future transition to 450 mm wafers, the total force required to probe a wafer increases if there is no reduction in the force per probe. This wafer prober chuck needs to apply the required force by pushing the wafer against the probe card typically held in place by the structure of the prober. With 200K probes on a 450 mm wafer each requiring 5 gF this is approximately equal to 1 ton (2205 lbF) of applied force. To reduce these force requirements wafer chuck and prober structure, Advantest and JEM have Continue reading “IEEE Semiconductor Wafer Test Workshop 2012 – Session 5 (Tuesday)”
Larry Levy (FormFactor, Inc.), “Is Parametric Testing About To Enter a Period of Growth and Innovation?”:
Upwards of one thousand facilities perform parametric wafer testing (based on 2009 market data) with over a third of these using obsolete test equipment. There have been no really new testers in several years – Agilent still has their 40xx series and Keithley has their S530 tester. And several companies have exited the market and some companies (including Keithley) are no longer supporting older models of testers. Since parametric testing remains an essential process, this has forced a high number of these facilities to use obsolete equipment or find other approaches. A few companies are going as far as using an Advantest 93000, a significantly more expensive and highly sophisticated digital tester, for parametric test. [Updated to clarify Keithley’s status.]
Tommie Berry (FormFactor, Inc.), “Actual vs. Programmed Over Travel for Advanced Probe Cards”:
As the number of probes on a probe card increase, the total force required to compress these probes – know as probe force – is increasing. With high force the actual over travel (AOT) – also know as overdrive – of the probe is often significantly different than the programmed over travel (POT) programmed in the prober. Even though memory test engineers with very high probe count cards have Continue reading “IEEE Semiconductor Wafer Test Workshop 2012 – Session 2 (Monday)”
This year’s IEEESemiconductor Wafer Test Workshop started on Sunday June 10th with a pleasant surprise. Due to a welcomed but unexpected wave of seventy walk-in registrations, there was insufficient seating at the opening dinner. Thankfully the hotel staff quickly adjusted to accommodate these additional guests. Attendance and interest in this year’s workshop was clearly up.
Jerry Broz, general conference chair, welcomed everyone with a brief overview and presented prizes for the first annual golf tournament. We then quickly proceeded with business as Matt Nowak (Senior Director, Advanced Technology, Qualcomm CDMA Technologies) provided the keynote “Emerging High Density 3D Through Silicon Stacking (TSS) – What’s Next?” Mr. Nowak discussed the increased amount of hype within the 3D semiconductor packaging market in the last year with everyone announcing something. And Thru Silicon Vias (TSVs) technology has already been in high volume production for image sensors for several years now but at a significantly lower density than for 3D packaging.
I discussed lower cost solutions that appear counter-intuitive since they require increased technical and operational complexity. Challenges of testing MEMS devices while still on wafer (prior to packaging and singulation) were discussed along with a review of MEMS solutions at this year’s IEEESemiconductor Wafer Test Workshop.
With the proper skills, experience, and perspective it is possible to avoid “re-inventing the wheel” and to develop the best strategy to profitably introduce new technologies to high volume manufacturing.