Edge bond pads on integrated circuits

[0002] This application claims priority under 35 USC §119(e)(1) of provisional application Ser. No. 60/088,763 filed Jun. 10, 1998.

[0003] The invention relates to integrated circuit devices, and more particularly to integrated circuits having top and edge bonding pads.

[0004] With the increasing density of components in integrated circuits, it is becoming more difficult to provide the necessary leads and contacts to the integrated circuit device. The larger number of bond pads requires more leads on the lead frame.

[0005] One approach to providing a high density bond pad layout is disclosed in U.S. Pat. No. 5,635,424, in which composite bond pad structure and geometry allows an increase in bond pad density. The bond pad density is increased by laying out certain non-square bond pads which are shaped, sized and oriented such that each bond pad closely conforms to the shape of the contact footprint made therewith by a bond wire or lead frame lead.

[0006] Another approach used in interconnecting a stack of integrated circuits is to provide a metal edge contact that is connected to surface areas by connecting conductors. This approach is disclosed in U.S. Pat. No. 5,107,586.

[0007] The invention is to a device and the method of making circuit devices with side wall contacts produced on a semiconductor wafer by forming grooves partially through the wafer surface to provide a plurality of device elements on a common base. After the groves are made in the semiconductor wafer, each device element has a top surface and sides surfaces. A semiconductor device or integrated circuit is then formed in the top and side surfaces by well known techniques, including diffusing and deposition processes, to form a semiconductor device. Contact pads are formed on both the top and sides of the device to provide a greater density of contacts for the semiconductor device. The semiconductor devices are separated along the grooves to provide individual devices.

[0008] The invention is also to the individual device in which contact pads are on both the top side of the device and the sides of the device.

[0009] FIG. 1 shows an example of a prior art process for producing the individual die component of an integrated circuit;

[0010] FIG. 2 shows the process for producing 3D surface integrated circuits;

[0011] FIG. 3 shows a semiconductor wafer according to the present invention;

[0012] FIG. 4 is a cross-section view of the wafer of FIG. 3;

[0013] FIG. 5 shows a prior art integrated die with top surface bond pads;

[0014] FIG. 6 shows an integrated circuit die according to the present invention; and

[0015] FIG. 7 shows a second integrated circuit die according to the invention.

[0016] In the process of manufacturing integrated circuits and other semiconductor devices, the prior art process shown in FIG. 1, a thin wafer of semiconductor material is polished (10) to provide smooth surfaces on each surface of the semiconductor wafer. Next components, interconnections and contacts are formed (11) in or on one of the wafer surfaces. These elements are formed by diffusion and deposition processes that are well known. Multiple devices are formed on the wafer. After the various components have been formed in and on the wafer, the wafer is cut (12) into elements generally referred to as semiconductor die, a die being a single device. The “cutting” process may be formed by sawing, or by scoring lines to separate the die and then breaking the wafer along the scored lines to separate the wafer into individual die.

[0017] FIG. 2 shows a basic process flow diagram of the present invention. As in the prior art process of FIG. 1, a semiconductor wafer is prepared by polishing its flat surfaces (20). The process of forming a plurality of individual devices (22) is preceded by partially cutting or sawing (21) into the surface of the polished wafer to define the individual semiconductor die and to expose a three dimensional surface. The wafer is cut to a depth to allow edge processes, and to allow the wafer to remain a single entity until device separation is desired. The depth cut around each device may be in the range of 25% to 75% of the wafer thickness, but this is not a limiting range as shallower or deeper cuts may be used in some processes. In the prior art process, only the top surface of a die, or the wafer is exposed to the various diffusion and deposition processes. In the process of FIG. 2, the edges of each individual die are also exposed as a result of the sawing or cutting in the surface of the wafer. This permits diffusions and depositions to be made into both the top and edges of each die by well known processes.

[0018] After the various process steps have been performed (22) and each individual die is complete, the wafer is then separated into the individual die by, for example, rolling the wafer with a roller.

[0019] FIG. 3 shows a wafer 30 that has been sawed to provide grooves 33 and 34, at 90 degree angles to each other, for separating the wafer 30 into a plurality of individual die 32. Each die 32 has four edges 32a-32dexposed as a result of the grooves 33 and 34. The base portion 31 of wafer 30 has not been cut through by grooves 33 and 34, holding the individual die 32 together.

[0020] FIG. 4 is a cross-sectional view, taken through section 4—4 of FIG. 3. Grooves 34 are shown separating the die 32. Base 31 is shown under, and forms a part of each die 32.

[0021] FIG. 5 shows a prior art device 32 with die 35 having contact pads 37 on the top surface 36. There are no contact pads on any of the sides 35a-35d.

[0022] FIG. 6 shows an example of a separated die 32 after circuit elements have been formed thereon and contact pads deposited onto a contact areas. Contact pads 37 have been formed on the top surface 36 of each die 32 and a plurality of contact pads 40 have been formed on the sides of die 32. In the example of FIG. 6, contact pads 40 have been formed with the upper edge of each contact 40 extending to the top of the side, for example sides 38a-38d.The contact pads 40 may all be placed in a common position on the side of die 32 with the edge extending to the top surface as shown in FIG. 6, or the contact pad may be positioned below the top edge of sides 38a-38d,for example, as contact pads 41 illustrated in FIG. 7. The contact pads 40 and 41 may be at various positions as needed by the specific circuit connections on the device 32. Both circuit elements and interconnecting wiring on device 32 may be on the top surface 36 or the sides 38a-38das required by the device configuration.