Page 34
www.us-tech.com
The Next Big Hurdle in Semiconductor Fabrication
By Frank J. Ardezzone, FJA Industries, Inc.
dled by end-effectors which grip the bottom of a wafer using vacuum. An end-effector can be described simply as the robot’s hand. The general practice is to use a vacuum clamp to hold the wafer on the end-effector as it is moved from place to place and then release it by terminating the vacuum and venting the vacuum line. The wafer is usually gripped on the bottom although there are other constraints and areas of preferred capture. The current chosen practice is to produce thinned wafers that are mounted on an adhesive-coated plas- tic film, which is in turn mounted on a metal transport frame. This prac- tice has been developed to solve the problems associated with ultra-thin wafer handling.
I
Ultra-Thin Wafers In order to enhance device func-
tion, wafers are now made paper-thin. While device function is enhanced, the handling of the wafer becomes prob- lematic. Wafers as thin as 100µ (ap- proximately 0.004 in.) are becoming commonplace, and because of their fragility they cannot be handled in the same manner as wafers of convention- al thickness (approximately 0.75 mm or 0.03 in.). Today, several handling methods exist for wafers thinned to
Wafer chuck with three-pin support.
transistor, known then as the “triple 02” device sold for $250 per transis- tor in a three-lead TO5 package. Today, you can purchase a computer chip for $35 that contains half a mil- lion transistors. In the early 60s wafers were 1 to
using manually aligned x, y, and z probes and a curve tracer. Wafer prob- ing came along and automated the testing of devices in wafer form, re- placing die testing and tremendously improving and expediting device test- ing. Wafer testing was a giant step for-
n the past, wafers were handled with tweezers or vacuum wands. Today, wafers are typically han-
half-thickness (0.38 mm or 0.02 in.) and two methods exist for ultra-thin wafers (0.1 mm or 0.004 in.). Over fifty years of hands-on
learning has allowed the fabrication of semiconductors to make giant leaps. In 1963, the first high-power
1.5 in. (25.4 to 38.1 mm) in diameter and carried hundreds, not millions, of transistors. We used tweezers to han- dle them and did die testing, not wafer testing. Wafers were cut into dice and aligned by hand on a gold-plated brass plate and tested one die at a time
ward for the industry which dramati- cally increased production testing, in- creased quality and reduced the num- ber of hands-on personnel. As automation became more
prevalent and device dice grew in size, so too did wafer size, leading to our current 450 mm (17.7 in.) diame- ter wafers. This continuous evolution has brought with it a lesser-seen is - sue which is now as important as the die testing issue was. This is the issue of the thin wafer.
Wafer Handling Methods In the accepted practice of han-
dling standard wafers, the wafer is gripped from the bottom using an end- effector then moved to the desired lo- cation and released. The released wafer is either placed in a cassette holder which supports it with rails on both sides, or the wafer is placed on a chuck which is again vacuum-activat- ed to hold it. When the wafer chuck is large and cannot be placed between the Y-shaped fingers of the end-effec- tor, the chuck is equipped with lift pins that fit inside the Y-shape of the end-effector. The pins then support the wafer while the end-effector vacu- um is turned off, which allows the end- effector to be removed before lowering the wafer to the chuck’s surface where vacuum is reapplied. This method works well for a standard wafer of 0.03 Continued on next page
Malcom RCX Series Modular Reflow Oven Profiling System
Winner of the 2016 NPI Award for Process Control Tools!
The Malcom RCX series modular profiler system includes:
Complete profiling of reflow ovens including oven temperature, video imaging, O2 concentration and convection air velocity.
Verification of oven optimal performance
Enabling user troubleshooting of oven process
Offering 6 and 12 channel reflow thermo-profiling
Suite 100 Main: 310-540-7310
Main: 770-446-3116 Fax: 770-446-3118
October, 2016
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100