Nasser Ali Jafari Heather McGill

Transcription

1 Can I Correate my Probecard? Nasser Ai Jafari Heather McGi Inte Corporation Santa Cara, CA Southwest Test Conference June 8, /08/99 Ai Jafari/Heather McGi Page 1

2 Motivation Pad pitch and pad size are getting smaer so must the aignment and panarity specs. The error budget is sma, hence the specs are extremey tight. Miscorreation between buid, metroogy, and sort is consuming the majority of the error budget. 06/08/99 Ai Jafari/Heather McGi Page 2

3 Introduction There are severa sources of miscorreation that effect the critica parameters within a probecard s ifetime. These key sources of variation are: Panarity Copanarity of Patforms Motherboard Emuation Probecard Fexure Aignment Overdrive and eference Pane Scrubbing Surface (gass vs. sapphire vs. oxidized A) 06/08/99 Ai Jafari/Heather McGi Page 3

4 Panarity Copanarity of Patforms Motherboard Emuation Probecard Fexure 06/08/99 Ai Jafari/Heather McGi Page 4

5 Copanarity of Patforms Is there a way to achieve copanarity of patforms between buid, metroogy, and sort? The majority of panarity error occurs due to a ack of copanarity between the probecard and the testing patform 06/08/99 Ai Jafari/Heather McGi Page 5

6 Varying Patforms 15 Same Probe Card at Various Sites 10 Panarity (um Site #1 with MB #1 Site #2 with MB #2 Site #3 with MB # Pad Number 06/08/99 Ai Jafari/Heather McGi Page 6

7 Same Patform Same Probecard & Motherboard at Various Sites Panarity (um) Site #1 with MB #4 Site #2 with MB #4 Site #3 with MB # Pad Number 06/08/99 Ai Jafari/Heather McGi Page 7

8 Motherboard Emuation Can we emuate the environment in which probecards are run on the sort foor? There are three key components of motherboard emuation to consider: Pogo pin force on PCB Locking mechanism Vacuum 06/08/99 Ai Jafari/Heather McGi Page 8

9 Motherboard Emuation Probecard fixtures for buid and metroogy shoud emuate the same environment as with the test head. The inherent nature of the forces caused by things such as vacuum, pogo pins, and the ocking mechanism can induce an awkward reshaping of the probecard. Proper motherboard emuation is a prerequisite for addressing probecard fexure. 06/08/99 Ai Jafari/Heather McGi Page 9

10 Probecard Fexure How accuratey do we account for the fexure in probecard buid and metroogy testing? With an increasing number of probe needes and various rposers (i.e. spider, space transformer) the force appied by the probecard in the sort environment induces some amount of fexure in the probecard which effects panarity resuts. 06/08/99 Ai Jafari/Heather McGi Page 10

11 Probecard Fexure The key paces fexure is missed are: the buid process acks motherboard emuation ack of fexure accountabiity when testing and repairing a probecard on metroogy toos a probe can not accuratey be reworked if there is no pressure from the entire array on the PCB! 06/08/99 Ai Jafari/Heather McGi Page 11

12 Probecard Fexure Mode Locking Mechanism eference Surface Pogo Pins Vacuum/PCB esiience PCB & Spider esiience. Chuck / Probes Chuck/Probes > PCB&Spider esiience Sum of Forces = Locking Mechanism - eference Surface - Pogo Pins + Vacuum/PCB esiience - PCB&Spider esiience + Chuck/Probes 06/08/99 Ai Jafari/Heather McGi Page 12

13 Probecard Fexure Mode Constraints Side View Test Head Emuator Loads Pro/E mode Mechanica Modeing done by ahima Mohammed Pro/Mechanica Anaysis of PCB Dispacement for a 50b Load 06/08/99 Ai Jafari/Heather McGi Page 13

14 Panarity with Fexure Mode Fexure induced by one probe can effect the measured panarity of others PL (A) = 0 PL (B) = 1 PL (C) = 2 SPIDE PL (B) = 1 + Fs(A) PL (C) = 2 + Fs(A) SPIDE PL (C) = 2 + Fs(A+B) SPIDE A B CHUCK C A B C CHUCK 06/08/99 Ai Jafari/Heather McGi Page A B CHUCK C

15 Possibe Soutions The copanarity of patforms has to exist in every step, from the probecard buid and panarization process to the metroogy test and sort processes. Since the reference surface of the stiffener ring is the ony fixed reference pane, a fixtures need to be copanar to the ring. Utiization of avaiabe metroogy toos to panarize various patforms. Add panarity fexure specs to the probecard buid specifications. 06/08/99 Ai Jafari/Heather McGi Page 15

16 The Effect of Panarity on Aignment Panarity wi AFFECT your aignment data. If we do not correate panarity we wi not have correated aignment resuts. 06/08/99 Ai Jafari/Heather McGi Page 16

17 Aignment Overdrive and eference Pane Scrubbing surfaces (gass vs. sapphire vs. oxidized auminum) Trademark of Disney Corporation 06/08/99 Ai Jafari/Heather McGi Page 17

18 Overdrive & eference Pane What do we use as a reference pane for appying overdrive? When ooking at the ifetime of the probecard it has severa different reference panes. With these reference panes varying from patform to patform we can never correate aignment. 06/08/99 Ai Jafari/Heather McGi Page 18

19 Overdrive & eference Pane Techniques for estabishing X,Y resuts vary because of different reference panes Probe Card Buid Visua specified overtrave appied to gass Metroogy First touch of a probes Median Signa pane Prober Optica first touch (based on a or a seect few probes) Eectrica first touch (based on both signa & bussed probes) Eectrica median (based on both signa & bussed probes) Eectrica ast touch (based on both signa & bussed probes) 06/08/99 Ai Jafari/Heather McGi Page 19

20 eference Pane Miscorreation We increase our time of tweaking 100X by changing the reference pane from first touch (a probes) to median pane (signa probes). If we took 1 minute to tweak a probe then our probecard repair time increases from 2 minutes to 3 hours and 20 minutes. Can we afford this? Which method actuay correates to the prober? # probes tweaked Max scrub Min Scrub Metroogy at median um 9.1 um Metroogy at 1st touch um 6 um 06/08/99 Ai Jafari/Heather McGi Page 20

21 Aignment at Median Signa Median Pane (signa) X,Y OD# /08/99 Ai Jafari/Heather McGi Page 21

22 Aignment at 1st Touch 1st Touch X,Y OD# o cock position /08/99 Ai Jafari/Heather McGi Page 22

23 Aignment at Various OD 1st Touch OD Comparision OD#1 < OD#2 < OD# OD#1 OD#2 OD# /08/99 Ai Jafari/Heather McGi Page 23

24 Aignment at Various OD Median Pane OD Comparision OD#1 < OD#2 < OD#3 3 o cock 20 position OD#1 OD#2 OD# /08/99 Ai Jafari/Heather McGi Page 24

25 Overdrive & eference Pane The reference pane used is a key factor for aignment data Overdrive is aso a critica parameter Therefore both the reference pane and the overdrive must be controed and correated 06/08/99 Ai Jafari/Heather McGi Page 25

26 Scrubbing Surface Are we accuratey abe to compare the scrub ength of a probecard? There are severa factors that vary: Different materias (gass, sapphire, oxidized auminum) - of which each has a different friction coefficient Various degrees of how much the materia deforms as it is scrubbed Amount of bending of the probe tip due to friction forces 06/08/99 Ai Jafari/Heather McGi Page 26

27 Scrubbing Surface Diagram Sapphire / Gass (Non-Deforming) Auminum w/ Oxide (Deforming) 06/08/99 Ai Jafari/Heather McGi Page 27

28 Bending of Probe Tip Common bending characteristic of probe tips due to friction 06/08/99 Ai Jafari/Heather McGi Page 28

29 Possibe Soutions - Aignment Set up a structure which wi communicate to a processes (buid, metroogy, and sort) what needs to be done to correate data Incorporate modeing to compensate for the differences in scrub between the various surfaces 06/08/99 Ai Jafari/Heather McGi Page 29

30 Where do we go from here? Probecard, metroogy, and prober suppiers need to work with semiconductor manufacturers to achieve correation by defining the critica parameters which we have discussed today. Money saved reduced tweak time minimizing reject rates extended ifetime of probecards reduced chuck force requirements 06/08/99 Ai Jafari/Heather McGi Page 30

31 Contact Information Nasser Ai Jafari - Inte Test Tooing Operations nasser.jafari@.com 408/ Heather McGi - Inte Test Tooing Operations heather.mcgi@.com 408/ /08/99 Ai Jafari/Heather McGi Page 31