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Volume 31 (Nov 15, 2004)
The path traveled by the creators of the NP Series of ultra-low on-resistance power MOSFETs for automobiles (2/2)
Part 1: Breaking the 2m ohm barrier
Reversing the tides and taking on the challenge of striving to become the industry leader
The team's journey began in July 2002 with a directive from then Division Manager Takahashi, the person in charge of power MOSFET development: "We must focus our efforts on developing a power MOSFET with an on-resistance value of 2m ohm." Development was already underway for a new power MOSFET that would use a 0.35µm process to realize an on-resistance value of 2.4m ohm, but this project was discontinued and it was decided that the team would switch its focus to the development of a power MOSFET with an even lower on-resistance using a 0.25µm process (Figure 2). Use a finer process would make it possible to decrease the size of the unit cells. In turn, high integration would become feasible. Doing so would not only improve the performance, but also decrease on-resistance. Although it was only natural considering the circumstances, the development team members were unable to hide their confusion over having been instructed to skip over the roadmap for the product that they had originally planned to develop.
Team Manager,
Power Management Device Division,
Power MOSFET process R&D
The rival manufacturer had already put its 2.3m ohm product on the market, so even if NEC Electronics were to continue on with its development of a new power MOSFET with a 0.35µm process and realize an on-resistance value of 2.4m ohm, it would just barely catch up to the level of its rival. Moreover, there was growing demand in the automobile sector for an on-resistance value of less than 2m ohm. This meant that if NEC Electronics were to survive in the industry, it would need to aim for a higher level. However, abandoning a product that was already under development without putting it on the market would mean that the time and money already spent would be a complete waste. Furthermore, it could be said that aiming for a higher level without even knowing if it was actually possible was a reckless move.
Since the 0.25µm process for power MOSFETs was the fundamental development level at that time, "We couldn't secure the manpower and environment necessary for development even if we were suddenly told to move ahead with the project," said Kenya Kobayashi, team manager of the process development team. And unfortunately, in March of the same year, the trial production line at Sagamihara was closed down, thereby making it even more difficult to carry out power MOSFET process development. Yet, the challenge the team had undertaken could not be swept aside by simply saying, "This is impossible." Team members knew that something had to be done. As time went by and after much consideration, they began to sense that their feelings of anxiety and confusion were transforming into a strong desire to face this challenge.
"Let's strive to develop a power MOSFET with an on-resistance value of less than 2m ohm. We need to turn this crisis into an opportunity to come from behind and become the industry leader. This is a challenge to break the 2m ohm barrier!" With that determination in his heart, Kobayashi turned his efforts toward development and began moving forward.
The launch of the project thanks to the cooperation of NEC Kansai
Without delay, Kobayashi began considering how to secure a trial production line and whom to ask for cooperation with development. Of the candidates on his list, he decided to approach the NEC Kansai Factory in Shiga prefecture because of its experience with power MOSFET fabrication. However, this decision did not work out exactly as he planned. The line at the factory was operating according to a schedule that had already been decided in advance. Kobayashi understood that the factory could not deal with irregular requests like the one he was about to make. Moreover, he was in effect requesting cooperation for experimental production and development, beginning in the process development stage, despite the fact that he and his team didn't even know when they would be able to realize commercialization of the product. Common sense told him that having his request denied was inevitable. However, even if he did get turned down, giving up was not an option. He would have to somehow find a way to convince those in charge to agree to his request. Before abruptly making his request for trial production, Kobayashi decided that he would need to begin by asking for everyone's patience and careful consideration of his proposal. It didn't matter if it took time.
Kobayashi immediately decided to visit the NEC Kansai Factory. In a stroke of good fortune, one of the development team members there agreed to spare some of his valuable time to speak with him. Kobayashi spoke cordially and with great zeal about the automobile industry's need for a low on-resistance power MOSFET, the present state of NEC Electronics' products, his vision for the future and the team's enthusiasm for this project. Afterward,Kobayashi received the answer he had been cautiously hoping for: "By all means, let's go for it!" It was at then that the team embarked on this project aimed at developing the industry's top automotive power MOSFET. The real challenges were just beginning.
