Semiconductor Industry Overview Industry Overview The semiconductor industry has experienced significant growth in recent years due to an increasing demand for semiconductors. This demand has resulted from the gowth of existing markets such as personal computers, telecommunications, consumer electronics, automotive electronics and office equipment, as well the development of applications such as multimedia, wireless communications and portable computing. Growth in these markets has been driven in large part by continuing improvements in semiconductor performance ( as measured by functionality, processing speed and memory) at declining cost per function. While the cost of manufacturing and IC may continue to increase, the cost per function for end users must continue to decline if demand is to be sustained. The market demand for higher performance and higher density semiconductor devices is pushing the limits of semiconductor wafer processing technology. Customer demands and technological advances are steadily driving semiconductor manufacturers toward the production of ICs with smaller features. As customers demand higher processing speeds and greater memory capacity, semiconductor manufacturers are forced to reduce feature size in order to provide greater performance on an IC of a given size. In addition, the overall economics of manufacturing an IC is directly related to the manufacturer's ability to reduce the size of a given IC; the smaller the IC, the greater the number produced per wafer, which increases the revenue per wafer and reduces overall cost per IC. ICs are already highly complex, built-up from ten to thirty thin layers, incorporating submicron (less than 1 micron) feature sizes, and requiring more than 200 separate processing steps. In the next few years, the requirements of advanced ICs, such as high density dynamic and static random access memory chips (DRAMs and SRAMs), will increase the number of thin film layers, reduce film thickness, reduce feature sizes from the current 0.5 micron to 0.25 micron and smaller, and increase the number of processing steps. As ICs have become more complex, both the number and price of process tools required to manufacture semiconductors have increased. In the late 1980s, a state-of-the-art semiconductor manufacturing facility cost about $500 million, with the value of equipment representing approximately 50% of the total facility cost. Today, a state-of-the-art semiconductor manufacturing facility costs in excess of $1 billion, with the value of equipment representing between 65% and 75% of the total. In addition, the higher complexity of ICs has increased significantly the value added by the semiconductor manufacturer to the wafer during processing. As a result, the cost of processed wafers has increased dramatically since the 1980s. With a single processed wafer now valued in the thousands of dollars, the cost impact of losing wafers in the event of a process failure is unacceptable. The increased investment required by semiconductor manufacturers, in terms of both processing equipment cost as well as investment per wafer, has caused these manufacturers to focus more closely on the yield, throughput, reliability and cost of ownership associated with each piece of processing equipment. Yield, the fraction of wafers processed that are of acceptable quality, as well as the fraction of devices on each wafer that are of acceptable quality, throughput, the rate at which wafers are processed, and equipment reliability, measured in terms of mean time between failure and mean wafers between failure, are the key factors in determining the economic viability, or cost of ownership, of a particular piece of processing equipment. Consequently, any new semiconductor processing technology or system seeking to address the next generation of ICs with feature sizes of 0.35 micron and smaller must have a low cost of ownership resulting from high yield, high throughput and a high level of reliability. Plasma Technologies Each step of the manufacturing process for ICs requires specialized manufacturing equipment. The three primary steps in manufacturing ICs are the deposition of insulating or conducting materials onto the wafer (deposition), the projection of a pattern through a mask onto light sensitive materials known as photoresist (photolithography), and the etching or removal of the deposited material not covered by the patterned photoresist (etching). Plasma technology plays an important role in the etch and deposition operations. Today, plasmas are used for virtually all etching processes, as well as significant and increasing percentage of deposition processes, most notably CVD. Based on industry estimates, AOT believes that, in 1994, approximately $10 billion of semiconductor wafer fabrication or "front end" equipment was purchased, with etch and CVD equipment each accounting for approximately 20% of this total. Plasma is generated when a power source transfers energy to a gas, or more specifically, by the ionization of gas through energetic electron bombardment. Plasma consists of negatively charged (electrons), positively charged (ions) and neutral atoms or molecules, and can be most simply defined in terms of three physical properties: density, pressure, and energy. Density describes the average number of electrons in a given volume and is typically defined in terms of electrons per cubic centimeter (cm -3). Pressure describes the number of neutral atoms or molecules in a given volume and is defined in terms of millitorr (mtorr). The energy of the charged particles is very dependent on how the external power is coupled into the plasma and on the neutral gas pressure. The energy of plasma ions or electrons is measured in terms of electron volts (ev). Each of these physical properties is interrelated, and a change in one will typically produce a corresponding change in the other two. During the plasma etch process (also known as "dry" etch), a semiconductor wafer is exposed to a plasma composed of a reactive gas, such as chlorine, which etches away selected portions of the layer underlying the patterned photoresist layer. The energy of the gas particles that are reacting with the layer in increased when that gas is in a plasma state, and this increases the ability of the reactive gas to etch away the selected portions of the layer to which the process is being applied. In addition, when in a plasma state, the reactive gas ions in the plasma strike the surface of the wafer at a perpendicular angle, which greatly increases the vertical etch rate. The three properties of the plasma (density, pressure, and energy) also define how suitable a given plasma process may be for semiconductor manufacturing. These properties play a significant role in determining whether the plasma process can produce high levels of yield and throughput. Density: For semincondutor manufacturing, a higher density plasma is generally preferable to a lower density plasma. A higher density plasma increases the number of plasma particles reacting with the layer being etched, which increases the rate at which the wafer is etched, resulting in higher throughput. Pressure: In general, as the critical dimensions of the features on a semiconductor device continue to decrease in size to 0.35 micron and smaller, lower pressure plasma processing is required in order to produce acceptable yield and throughput. First, as critical dimensions shrink, the ability to etch wafers with more precision, so that the sidewalls of features are nearly vertical and have minimum undercutting, is critical for producing acceptable yield. In addition, as ICs become more complex and are designed with features of varying dimensions, an effect known as microloading can occur in high pressure systems. Microloading, the effect of etching larger features more rapidly than smaller features, generally results from high pressure etching and can significantly decrease manufacturing yield. Ion Energy: For a number of reasons, low energy ions reacting with the wafer are preferable to high energy ions during the semiconductor manufacturing process. fabrication processes which bombard the wafer with high energy ions can damage the wafer, cause particulates to form on the wafer, or cause electric charges to build up on device structures, all which lead to lower manufacturing yields. In addition, fabrication processes must precisely control the thickness of the various material layers on the wafer, and it is necessary to be able to etch one layer without etching the underlying layers. A process that is able to meet this requirement is said to have a high selectivity, and processes utilizing low energy ions tend to have a higher level of selectivity, and therefore produce higher yields, than processes using high energy ions. We believe that Reactive Ion Etching (RIE) is unable to achieve the combination of high density, low energy and low pressure required to meet the yield and throughput requirements for etch and deposition applications below 0.5 microns. To reduce feature sizes, etch systems must be capable of operating at low pressure to avoid undercutting of features and microloading, both which result in lower yield. In order to increase the etch rate at this low pressure, a high density plasma is needed to provide adequate throughput. About Entiv Our Values Patents Services Our Team Contact Us © 1985-2010 Entiv Data Systems, Inc ™, All Rights Reserved.