Semiconductor manufacturing is deceptive to a certain extent, because semiconductor factories usually do not have chimneys that emit pollutants. In addition, the industry offers high-paying jobs and other characteristics that are different from past manufacturing jobs. However, a semiconductor manufacturing plant is essentially a chemical plant with electronic output.
The resource density of the semiconductor manufacturing industry is huge. In a recent article (Williams, ED; Ayers, RU; Heller, M. Surrounded. Science. Polishing process. 2002, 36 (24); According to the survey, every 2 grams of 32mb DRAM produced, Need to use 1.7 kg of chemical substances and fuel. If you only consider water, every 2 grams of chip requires 32,000 grams of water. However, a lot of water is recycled in plants, a lot of water is reused, but the water is deionized, Converted to a very high energy content. For every 2 grams of chips, 45 grams of chemical products are also used.
Water is indeed a big problem here. A typical semiconductor manufacturing plant uses 2 to 3 million gallons of deionized water every day. Typically, these factories are located in semi-arid areas of the United States (for example, Austin, Texas; Albuquerque Nano; San Jose, California, and Irvine, California) and they are already struggling with water problems. However, this kind of water use is not a big problem for the industry because it is economically affordable. For example, at its plant in Albuquerque, New Mexico, Intel purchased water rights from farmers up and down the Rio Grande so that there would be enough water for its processing. Because the value of water is very high, it is reasonable to buy water at such a high price.
Then, something happened that changed this happy scene. This industry has encountered a physical problem. The ratio of the width to the depth of the function (aspect ratio) is beginning to cause problems. When the characteristics of the wafer are generated, water containing water chemicals is used to clean the wafer. However, as the feature aspect ratio increases, the high surface tension of water inhibits its ability to penetrate between features. Subsequently, the industry had to look for cleaning methods other than water.
The solution to this problem comes from Los Alamos National Laboratory. Studies have found that supercritical fluids, especially supercritical CO2, can replace water for cleaning. This is because in the supercritical state, CO2 has no surface tension and can penetrate small spaces by adding propylene carbonate as a food additive. Figure 2.1 shows the improvement of supercritical CO2 purification performance. This technology has been commercialized, and the supercritical fluid technology has won the Presidential Green Chemistry Challenge Award. Now, six other companies are building new equipment for the semiconductor industry to implement this technology. Again, this is a speed limit issue, but one of the benefits is that 2 to 3 million gallons of water can be used for other purposes every day. Therefore, it is important to consider protecting water resources and reducing pollution in the equation.
The core of sustainable development is food and water. If food cannot be provided in a sustainable manner, it will be impossible to feed the current or future population. Providing adequate food and water has a lot to do with the chemical industry. The chemical revolutions of the 1950s and 1960s made it possible to produce enough food to feed the people on earth. The scale of the agricultural chemical industry is huge, with pesticides alone worth US$12 billion each year. This is a fairly healthy dollar figure, but it is unhealthy in terms of persistence and bioaccumulation. In fact, the environmental movement began in the 1950s when Rachael Carson discovered the pathway for the bioaccumulation of dichlorodiphenyltrichloroethane (DDT) in organisms.
Chemistry will play a key role in a sustainable future, but what kind of chemistry will it be? As far as herbicides and pesticides are concerned, as long as they are applied correctly in a scientifically responsible manner, they are not in most cases problem. However, all over the world, these chemicals are often handled incorrectly and proper safety procedures are not followed. Even in the United States, the typical person who uses herbicides and pesticides on the lawn does not always read or follow the safety instructions provided.
The question is how to avoid environmental pollution from the beginning. In the past few years, many Presidential Green Chemistry Challenge Awards have been awarded to agricultural applications and pesticide applications. There are more examples such as cockroach protection, ant protection and other household uses. Major companies are adopting different alternative pesticide systems, including bionic methods. Instead of using large-scale neurotoxins to attack a species, they are looking for more specific targets.