Innovations at both ends of the semiconductor manufacturing process Kawabe Shigeo, Engineer, DAITRON TECHNOLOGY CO., LTD., Morishita Tetsuya, Engineer, DAITRON TECHNOLOGY CO., LTD., Ozaki Masahide, Technical Manager, DAITRON TECHNOLOGY CO., LTD.

In the field of semiconductors, which has seen a precipitous rise in demand over the last few years, Daitron has put itself on the map with two significant systems in pre- and post-production processes of semiconductor manufacture, namely its chamfering system for grinding the wafer edge profile, and the chip sorter that enhances operation with automatic wafer chip sorting. We had the opportunity to speak with three of the elite team involved in the development of these powerful devices, to learn the inside story of how these systems came to be and the secrets to their resounding success.

INTERVIEW 1 Two systems that have made a mark on the world

Please tell us about the manufacturing equipment that Daitron produces for the semiconductor industry.
Ozaki:
The 2 main systems are the chamfering machine that processes the wafer (the raw material that forms the base for semiconductors) into a round profile, and the chip sorter that peels diced chips off their sheet and places them onto a tray for storage.
Kawabe:
The chamfering machine was sold first in Japan, but since then has been doing well all across the globe, from the US to China to Germany. So far, we've shipped more than 900 units. Having the technology for high precision and stable processing of the hard sapphire wafers, which are the basis for LED chips, places us in a pretty unique position in the world - I can't think of any place besides us that has that capability. Our products have become known as the world standard for sapphire grinding.
Morishita:
As for the chip sorter, we've sold over 700 units worldwide. We have more units operating than any other manufacturer in the market, and also have a long history that further solidifies the trust that customers place in our products. Even though our units are slightly more expensive than our competitors in the Taiwan market, for instance, customers still choose us.

INTERVIEW 2 Developing the first computer-controlled chamfering machine in the world

How did you start developing the chamfering machine that is now being shipped all over the world?
Ozaki:
Grinding machines at the time when we started development used an imitative method, meaning that first a master of the finished wafer would be made and then grinding would start on an unprocessed wafer using a wheel to achieve that shape, much like the process for duplicating a key. For instance, to make a 100mm-diameter wafer, first you would need to make a 100mm-diameter master - this type of analog method was the most common system in place then. Since we wanted to introduce something new into this field, we kept trying to find something more efficient and with greater precision, and so found a way to utilize computer-aided numerical control (NC).
Kawabe:
Our company was the first anywhere to incorporate NC into a chamfering machines. The drive uses a servo motor that can control position and speed digitally, which is another achievement this machine brought to the industry. It works by accurately grinding only that section for which numbers have been input, completely eliminating the need for a master and enabling full control over everything from grinding speed to position. We're now in the process of moving those technical achievements even farther, but at the time when the first chamfering machine was developed, it was a real breakthrough.
Morishita:
The bigger the size of the wafer, the more chips that can be sliced from it. So, in the 1990s, wafers measured 200 millimeters in diameter, which grew to 300 millimeters in the late '90s and so on, with the diameter of wafer growing over time. Our job is to listen to what our customers are working with in terms of outer diameter and edge profile, and to do what we can to comply with the processing quality that they need.

INTERVIEW 3  World-class technology for high-precision processing of materials from silicon to sapphire

Can you talk to us about the secret behind such highly acclaimed processing precision and the sequence of events that has led to sapphire grinding?
Ozaki:
At the time when demand for silicon wafers was growing in response to the introduction of LEDs, we were focusing on producing chamfering equipment that would offer a great deal of stability, excellent precision, compact dimensions and other features to really answer the needs of the moment.
Kawabe:
We've been steadily improving processing precision, through repeated trial and error, such as, for instance, changing the material of the grinding part from machined steel to a casting. Improving the hardness of the grinding part reduces vibration and so enhances processing precision. Then, as that precision gets better, processing speed naturally increases. That's the sort of holistic approach we are always working to achieve, to design for a total system in which all the parts work together toward improved results.
Morishita:
The problem in the development and improvement process had been the issue of costs going up when the priority was placed on grinding precision. We had been doing all the design and manufacturing in-house, but modified that to collaborating with outside specialty manufacturers. The result has been the realization of systems that today offer both precision and reliability as we specialize in developing the area of core technology. Compared with the earlier products, there have been real improvements in productivity and processing capability as well.
Ozaki:
The first chamfering machines developed for silicon wafers are also applicable for processing sapphire boards in terms of processing precision and stability. Even though we hadn't planned it that way from the start, we've been able to earn high marks from the market with our chamfering equipment that excels at sapphire grinding as the requirement for sapphire boards has continued to grow over the years.
Kawabe:
This is what comes from unceasing pursuit of product quality: we're able to respond to the needs of each new phase as the industry continues to push forward.

INTERVIEW 4 Development  efforts continue to seek ever greater processing precision

What do you foresee in the development of newer chamfering equipment?
Ozaki:
We're working on the developments to improve on last year's WBM series. While that has been quite a hit, we want to move forward to the next level, trying an entirely new approach to radically improve the freedom and precision for profile processing. To make a long story short, our aim is to enable a freeform edge profile. There are many cases where the wafer is processed so that it becomes ultra thin in the end, but when it gets that thin there can be breakage if the edge profile is poor. So we are looking ahead to a profile that would resist breakage from the start.
Kawabe:
Before the grinding process, the thickness of a wafer is about 0.8 millimeter. As that is ground away, the wafer thins to under 0.05 millimeter. That is less than half the thickness of a strand of hair, or less than a sheet of paper, and in fact the silicon gets so flimsy you can see through it (laughs). That thin wafer is what is now built into things like USB memory drives and micro SD cards.
Morishita:
Since you can layer more chips onto a single card if the wafer is thin enough, it's possible to keep increasing the capacity of micro SDs. By raising the precision of our equipment, we're able to foster innovation at our clients' facilities.

INTERVIEW 5 The power of

How do you account for the high acclaim that has been accorded to the chip sorter?
Ozaki:
We have been making chip sorters for a long time; all along, they've been in a niche market that we've managed to maintain by responding to what our customers need with careful, attentive service.
Kawabe:
It's a simple thing, really: the idea is that a needle holds the top of a chip by suction, and we happened to come up with it before anyone else. Then, depending on the size of the chip, the trick is to adjust the position of the needle so that it is able to pick the chip up without damaging it.
Morishita:
Our sorters are designed with the pick-and-place mechanisms near (and parallel to) the front of the system where they are easy to check and adjust. Many of our competitors' units place these mechanisms toward the back where it's harder to see how the operation is going. While it isn't a big deal, simply a difference in how the design is approached, it shows how we have taken into account our customers' responses when we ask them what they consider to be important. This layout is an example of that: it is very easy to use, and has led to customers giving us high marks.
Ozaki:
We have a specialist who has been working on our chip sorters for so long, both designing them and setting them up, that we call him "the maestro." He is a storehouse of knowledge and passionate about being able to pick up and store any chip in the world, to the extent that he is not simply answering customers' needs, he's foreseeing them. I hope we can keep pursuing the chip sorting route into the future. We're now devising systems that will amaze the industry and delight our customers, so stay tuned - there is more to come!