While thin semiconductor wafers offer many advantages, including a wide range of mechanical capabilities, greater integration of applications and larger chip storage space, semiconductor suppliers commonly run into issues due to the thinness of the wafers. Thin semiconductor wafers have negative properties that can produce a significantly high percentage of breakage during semiconductor processes, reducing the yield of products, which is a huge problem for semiconductor suppliers and others in the industry.
Many semiconductor suppliers use thicker bulk wafers that are thinned down during semiconductor processes, but today, most in the industry opt for very thin wafers, with a thickness of only tens of microns, from the start. Using thinner wafers at the start of the process does reduce some of the risk of breakage or other damage as it removes the need for the final processes, such as grinding and polishing, which often are the main sources of breakage. Although true, it is important to note that thin semiconductor wafers still do not have a great mechanical strength, which makes them susceptible to damage as they move through the earlier stages, such as cleaning, coating and etching.
In order to counter the poor strength of the thin wafers, semiconductor suppliers are beginning to turn to a temporary bonding technology called reversible wafer bonding. The following is a list of basic steps involved:
- Prepare Wax. Various types of wax act as adhesion promoters to bond thin silicon or other delicate compound wafers to a carrier substrate. The type of wax chosen is based on the highest temperature involved in the process to ensure that the substrate is able to withstand the heat. After the appropriate wax has been determined, it is then placed at high temperatures on the wafer surface using a variety of tools, including heated dispense lines, pumps and chucks.
- Bond Wafer and Substrate. After the wax adhesion promoters are uniformly applied, the wafer is placed in a heated bond chamber. The wafer and substrate are mechanically aligned, and then are lightly pushed together to create a temporary bond, which allows for further processing, such as backside lithography and thinning.
- De-bond Wafer and Substrate. After the steps of the process are complete, the wafer and substrate can then be de-bonded. Depending on the type of wax adhesion promoters used, the two components can be de-bonded by either a special heating process or dissolution in a solvent.
Reversible wafer bonding uses functional resins and adhesion promoters to temporarily apply the wafer to a carrier substrate. This bonding technology allows semiconductor suppliers and others in the industry to reduce the risk of breaks and other damage to thin wafers during semiconductor processes, increasing their overall product yields.
If you are interested in high quality functional resins, adhesion promoters or other semiconductor supplies for your operations, trust in Shin-Etsu MicroSi, a highly reputable semiconductor supplier. Our products can help you to implement reversible wafer bonding, leading to a more effective semiconductor production system. To learn more, call Shin-Etsu MicroSi at (480) 893-8898 or contact us online.