1978 One Minute Story The most precise machine in human history

A firm belief and superior technology created steppers

In 1976, aiming to boost the semiconductor industry in Japan, a national project: the VLSI (very large scale integration) Technology Research Association (hereinafter, VLSI Research project) was formed with MITI (The Ministry of International Trade and Industry, at that time) leading the way.

The VLSI Research project took on a theme called ultimate LSI and advanced the development of semiconductor manufacturing equipment.

This is the equipment that exposes highly complex circuit patterns onto a silicon wafer, which is a material essential for manufacturing semiconductors.

There were three types:

[The direct etching method that uses electron beams.][A method that uses X-ray exposures.][The stepper method that employs visible light as the source of exposures.]

Nippon Kogaku (current: Nikon) received an order from the VLSI Research project for a prototype equipment. What Nippon Kogaku was going to develop was the stepper method that utilized light for exposures. This was the third idea, that was not really thought to be feasible and was only being considered as a reference point.

A staff member of the VLSI Research project: The stepper method will be difficult to utilize for processing in future generations.

Why was the stepper method not considered feasible?

Making sub-micron (less than a micrometer) devices was targeted at that time. In order to achieve this using the stepper method, a lens capable of defining lines that are equivalent to 50 or more lines within the cross section of a single strand of hair is required.

A staff member of the VLSI Research project:Considering common sense, it is hard to believe it's possible to make lenses achieving such high resolution.

To control the stage for the wafer, it requires an accuracy equivalent to hitting a tennis ball on the summit of Mt. Fuji with an arrow shot from Tokyo. How would that ever be possible?


I believe it's possible!

Shoichiro Yoshida who was in charge of development at Nippon Kogaku (current: Nikon)  thought he could actually achieve it.

Three things were needed for realization:

A high-resolution projection lens that was the heart of the stepper, an ultra-precise high-speed stage that moves the stage for the wafer faster and with high precision, and a photoelectric sensor necessary for the automatic control mechanism.

High-resolution projection lens Ultra Micro-NIKKOR
The basis for the ultra-precise high-speed stage of Ruling Engine No.2

Nippon Kogaku possessed all of these at that time.

Here is how the most precise machine in human history that Mr. Yoshida and his colleagues realized changed society...

The trigger that propelled the semiconductor industry

Method of Stepper

A stepper is a machine used to reduce the size of circuit patterns on a photomask (a large glass plate for creating fine, complicated electronic circuit patterns) by employing an ultra-high-performance lens to project the patterns onto a silicon plate, called a silicon wafer. It is equipment that plays an essential role in semiconductor lithography manufacturing.
The individual technologies required in order to realize it were available at Nippon Kogaku. However, collaboration between three kinds of technology was also needed for smooth development: "optical design" to create lenses, "machine design" for manufacturing precise machinery, and "electronic design" for electronics-related matters. Shoichiro Yoshida, who was the project leader, created the environment that made all of this possible. There was also the firm will to take on the challenge of developing evolved reduction projection exposure equipment which could cope with semiconductor circuits that were certain to become even smaller in the future.
The first stepper prototype, the SR-1, was completed in July 1978. The VLSI Research project gave its performance high evaluation. At that time, a major American precision equipment manufacturer had already introduced reduction projection exposure equipment, and steppers were in the spotlight as the mainstay next-generation semiconductor manufacturing equipment.
Mr. Yoshida was certain that using steppers was the only viable exposure method that could effectively handle the evolution of semiconductors. He decided to commercialize the product and started making a prototype for mass production. In March, 1980, the SR-2 was completed. This was the start of the stepper business at Nippon Kogaku, and this led to the rise of the semiconductor industry.

Contributing to realize a super-smart society

FPD Lithography Systems FX-103S optimized for manufacturing high-definition large-sized panels

Technologies and knowledge cultivated through the stepper business are also now utilized for FPD lithography systems that are the manufacturing equipment used for flat panel displays such as LCDs.
Steppers expose semiconductor circuit patterns onto silicon wafers. On the other hand, FPD lithography systems project switch functions that control each RGB color onto glass plates which are the base of FPDs.
The equipment is becoming larger to handle production of 10.5th generation glass plates with a size of 2940 x 3370 mm.
Currently, Nikon's FPD lithography systems are utilized for manufacturing various FPD products such as smart devices, tablets, thin home TVs and outdoor digital signage, to support a super-smart society.