New developments in field of dicing
Mr. Kruse, what problems in the field of thinning and wafer dicing are the most relevant at the moment?
First, I would like to note the problem of delamination in materials with a small dielectric constant (low-k) during mechanical separation of chips. Our laser dicing technology allows to solve it. Another problem is caused by the development of advanced packaging and the tendency to obtain increasingly thin-layer structures used in devices for mobile electronic equipment. For this area we have developed a new solution – CONDOx, which allows us to combine our technologies, including wafer grinding, blade and laser dicing, and if it is necessary to obtain flexible chips – plasma etching of the wafer backside to reduce mechanical stress.
CONDOx is a newly developed solution for processing wafers on which bumps with a height of up to 150–300 μm are formed. High-quality grinding of wafers with bumps of this height for a long time was almost impossible. The new surface protection technology perfectly absorbs the wafer surface structures and enables processing without leaving residue on the wafer. Wafer of silicon or other materials can be processed with a total thickness variation (TTV) of less than 5 microns. When using CONDOx, the thickness of the wafer after thinning can be several times smaller than the height of the bump, which is impossible with the use of traditional technology. An additional advantage is the possibility of grinding the wafer with a 20–30% higher speed than usual. CONDOx allows you to use the usual equipment for grinding and polishing without the need for any of its modifications.
Does CONDOx increases the cost of wafer dicing?
No, there is no increase in costs. The prices of consumables are at the same level as the price of the usual mounting film, so they do not actually affect the cost of the chips. A mounting machine for lamination of the film to the wafer is inexpensive compared to other equipment used in the manufacture of semiconductor devices. At the same time, the numerous advantages of CONDOx contribute to the expansion of production capabilities, the attraction of new orders and the reduction of rejects, which can provide a real economic effect.
Lately there has been a lot of talk about the technology of plasma dicing, how do you assess its prospects?
For some applications, plasma dicing, of course, is the technology of the future. But at present there are a number of unsolved problems in this area. For example, if the structure of the wafer includes metal elements that are on the streets between the chips, separation using only plasma etching is impossible. For such cases, we can offer a combined solution using laser dicing for metal removal and subsequent plasma etching. But then the technology is not only more complicated, but it is also impossible to realize one of the main advantages of plasma etching – the reduction in the street width increasing the utilization factor of the wafer area. On the other hand, if you need to obtain non-rectangular chips, then plasma etching does not actually have competitors. Thus, currently plasma etching can not be considered an optimal solution in the field of wafer dicing, but certain niches for its application have already been outlined, and we offer our customers solutions, including on the basis of this technology.
Interview: Dmitry Gudilin