Patent GB-1421408-A (GB)
Title: Methods of separating discrete semiconductor chips from a semiconductor wafer
IPC: H01L21/304
Filed: 1973-04-13
Abstract: 1421408 Manufacturing semi-conductor devices INTERNATIONAL BUSINESS MACHINES CORP 13 April 1973 [26 April 1972] 17801/73 Heading H1K In manufacture of semi-conductor chips, e.g. for integrated circuits a diced wafer is attached to a support by a releasable bond of, e.g. glycol phthalate; the support having a pedestal portion and a circumferential flange portion, and the division extending into the bond or substrate. The support is mounted at 11 in a fixture 20 (Fig. 3) (Fig. 10) which has a base 21 and upstanding spaced walls 22A, 22B with inward ledges 23A, 23B overlying the flange 11B of the support with securing clamps 24A, 24B. The side walls bear upstanding dowels 27A, 27B. For orientation, fixture 20 adjustably is mounted on fixture 28 with fixed clamp 29 and spring clamp 30 on a base-plate 28A (Fig. 4). A jig 31 (Fig. 5) is placed on dowels 27A, 27B to enable proper alignment of the support relative to fixture 20 and comprises plate 32 apertured to engage the dowels, with a central bore 34 exposing the wafer. Annular recess extending outwardly from the bore contains three alignment devices 36A, 36B, 36C each with an aligning support and a dependent knife edge engaging predetermined dividing cuts when fixture 20 aligns with support 11. The jig is upwardly spring biased to elevate the dependent blades above the chip level so as to permit movement (Fig. 6, not shown), and after alignment clamps 24A, 24B are engaged and the jig removed. Secondary alignment means are provided (Fig. 7, not shown) located by dowels 48, 49 an annulus 31A circumscribing bore 34 (Fig. 5) which engage a circumferential lip of a transparent cover having cross wires and dependent circumferentially spaced legs entering bore 34. Fixture 20 is movable relative to support 11 until the cross wires are correctly positioned relatively to the chips (44A, 45A, Fig. 5). After alignment, support. 11 is clamped by 24A, 24B and jig 31 is removed; and then fixture 20 is removed from fixture 28 by release of clamps 30. Thereafter cover member 50 (Fig. 8) is clamped to fixture 20 and biases the chips to destroy bond 12. It comprises a plate with stepped recesses 51, 51A (Fig. 9) with a resilient porous pad 55 in the latter of similar diameter to the wafer 10, with apertures 58, 59 extending through the pad at 58A, 59A of which the former terminate in nipples 60 at chip spacing while the latter are aligned with the inter-chip divisions. Apertures 53A, 53B of the cover 50 are located on dowels 27A, 27B of fixture 20 and ledged recesses 54A, 54B engage twist locks 67A, 67B in the side walls 22A, 22B of cover 20 to grip the ledges (Fig. 10). A bond releasing fluid is forced against material 12 with the compressed nipples 60 absorbing the slack. The assembly 75 comprising fixture 20 and cover 50 enclosing support 11 and chips 13 is aligned on bed plate 101 by dowels 102A, 102B (Fig. 13) and apertures 59 (Fig. 14) in the lower surface of cover 50 register with apertures 103 in an insert 104 of bedplate 101. A reciprocating bellows pump 100 circulates the liquid through apertures 59, 103 aligned with the chip divisions in response to pressure fluid admitted through conduit 107. As bond is removed, the nipples extend until backs of the chips engage support 11, so that the assembly may be removed after disengagement of a retaining clamp slidable on a vertical pillar (Fig. 17, not shown). Assembly 75 is placed on a fixture 120 (Fig. 18) comprising plate 121 on legs 122 with divels (not shown) registering with holes 53A, 53B of support member 50 and retained by clamps 128A, 128B. Apertures 123 of the plate register with apertures 58 aligned with chips 13 while intermediate apertures 59 are closed. Vacuum through manifold 124 retains the chips in orientation, after which clamps 67A, 67B are released and fixture 20 with support 11 removed. A cover 125 retained by twist locks 126, 127 is positioned over the chips with apertures 130 (Fig. 19) aligned with their backs to prevent surface tension and a ridged surface. Alternatively a cover and pad similar to 50, 51 with vacuum through apertures 130 may be used. Specifications 1,412,409 and 1,412,410 are referred to.