Advances in Particle Removal without Damage

Particle removal without damage to sensitive device structures on semiconductor devices is a necessary process to maximum device yield. The use of an atomized aerosol spray for damage-free particle removal has proven to be one of the more effective strategies. Continued improvements in nozzle design have enabled the use of this technique to 1Xnm technology nodes. Recently, the freezing of water has also shown promise for damage-free particle removal, and the performance of this new technique is compared with aerosol spray cleaning.     

Membranbälge für die Vakuumindustrie in verschiedenen Sauberkeitsstufen

Edge welded bellows for the vacuum‐industry in different cleaning levels — Controlled, measurable purity for all markets The more and more demanding cleanliness specifications of the vacuum industry, especially semiconductor production, are a major challenge for the manufacturing and cleaning processes of suppliers in this market segment. Also the COMVAT AG as a manufacturer of edge welded bellows, used in the vacuum industry e.g. as a flexible sealing elements, faces up to the increased requirements of its customers. For this purpose, the entire process chain has been optimized from the design of the product over the manufacturing and final cleaning to the inspection and packaging in clean rooms up to ISO class 5 according to EN ISO 14644‐1. The installation of three cleanliness levels ?Standard”?, ?Advanced”? and ?High‐Purity”? allows supplying the suitable purity to the customers. Their specifications regarding the contamination classes of organic, inorganic (metals and ions) and particles were observed. The highest cleanliness grade, the high purity level, is achieved by a high‐quality ultrasonic wet cleaning process, optimized especially for the cleaning of edge welded bellows.     

Reinigung von Vakuumbauteilen für UHV‐ und UCV‐Anwendungen

Cleaning of vacuum components for UHV and UCV applications Ultra‐clean vacuum components and assemblies are fundamental to some cutting edge high‐tech sectors like semiconductor industry, particle accelerators, and surface analytics. Exceptionally critical for these applications are particles that stick at the vacuum facing surfaces as well as desorption of water and hydrocarbons from the surfaces into the system, because this may interfere with the sensitive ultra‐high vacuum (UHV) and ultra‐clean vacuum (UCV) processes. In this contribution, some established cleaning methods and surface treatments are discussed with respect to their effect on reducing particle contamination and outgassing of water and organic compounds from stainless steel surfaces. It is clarified that the resulting cleanliness severely depends on the detailed steps during the surface treatment and subsequent cleaning. As a consequence, the discussed methods should be chosen and adapted with great care according to the specific demands of the final application area.     

金属刻蚀后清洗导致AlSiCu互连线空洞问题的研究和对策

集成电路制造中,AlSiCu互连线一般使用干法刻蚀来制造,刻蚀后需经清洗工艺将残留物去除掉。而在清洗时,合金表面会出现空洞。我们在对空洞形成原理分析后发现,AlSiCu合金是由α相铝铜和富含Cu的θ相铝铜合金组成,在清洗过程中会发生电偶腐蚀而腐蚀Al。并且清洗使用的化学试剂由于含有胺根,水解后加剧了对Al的腐蚀。我们通过降低AlSiCu合金溅射时的衬底温度,将AlSiCu合金表面氧化,去离子水清洗时通入CO2这三种方案来防止AlSiCu合金在清洗时被腐蚀,从而提高了产品的成品率。     

Utilization of critical fluids in processing semiconductors and their related materials

The use of carbon dioxide in its various states: supercritical (SC-CO₂), liquid (L-CO₂) or pellet form (snow-CO₂) for processing and cleaning in semiconductor fabrication and related electronic devices is assessed in this review. An understanding of the fundamental mechanisms responsible for carbon dioxide-based processing, as in surface cleaning, is lacking. Although carbon dioxide is an excellent solvent for removing non-polar contaminants from a variety of surfaces, other CO₂-based cleaning and surface modification processes are based on mechanical or morphological-induced changes in the interfacial region. The extremely low surface tension of CO₂ is a favorable property in terms of its rapid and complete removal from the substrate after a treatment has been affected, and this characteristic of CO₂ also accounts for its negligible effect on the morphology of the substrate, as utilized in the microelectronic industry. Applications of critical fluids in integrated circuit manufacturing operations, such as wafer cleaning, film deposition, photoresist stripping, drying, and particulate removal are noted.     

Effect of Pre-heat and Inert Gas Species on Cryogenic Aerosol Cleaning Performance in Semiconductor Manufacturing

Cryogenic aerosol cleaning is a dry cleaning method used in the back end of line (BEOL) semiconductor manufacturing to remove defects from planar hydrophobic surfaces such as SiCOH and SiCxNyHz. Cryogenic aerosol cleaning is preferred over conventional wet cleaning methods as it is a non-contact cleaning method, which uses inert gases to generate sub-micrometer-sized solid aerosol particles that physically remove nanometer-sized contaminants on wafer surfaces. Particle removal mechanism involves detachment of the particles upon impact with aerosol, diffusion, and finally entrainment away from the wafer. In BEOL metal line patterning, particles on the dielectric isolation surfaces translate through the subsequent lithography and copper fill steps in to single or multiple metal line open defects that are yield killers. In this study, we show that the particle removal performance of the standard aerosol cleaning can be enhanced by pre-heating the wafer and use of a higher molecular weight inert gas, namely Ar, for aerosol generation. Both the addition of a Pre-heat step and the use of Ar as the aerosol source showed 47–52% reduction in single and multiple line opens detected through wafer electrical tests during high volume semiconductor manufacturing process.     

The simulation of air recirculation and fire/explosion phenomena within a semiconductor factory

The semiconductor industry is the collection of capital-intensive firms that employ a variety of hazardous chemicals and engage in the design and fabrication of semiconductor devices. Owing to its processing characteristics, the fully confined structure of the fabrication area (fab) and the vertical airflow ventilation design restrict the applications of traditional consequence analysis techniques that are commonly used in other industries. The adverse situation also limits the advancement of a fire/explosion prevention design for the industry. In this research, a realistic model of a semiconductor factory with a fab, sub-fabrication area, supply air plenum, and return air plenum structures was constructed and the computational fluid dynamics algorithm was employed to simulate the possible fire/explosion range and its severity. The semiconductor factory has fan module units with high efficiency particulate air filters that can keep the airflow uniform within the cleanroom. This condition was modeled by 25 fans, three layers of porous ceiling, and one layer of porous floor. The obtained results predicted very well the real airflow pattern in the semiconductor factory. Different released gases, leak locations, and leak rates were applied to investigate their influence on the hazard range and severity. Common mitigation measures such as a water spray system and a pressure relief panel were also provided to study their potential effectiveness to relieve thermal radiation and overpressure hazards within a fab. The semiconductor industry can use this simulation procedure as a reference on how to implement a consequence analysis for a flammable gas release accident within an air recirculation cleanroom.     

Ultrapture water: More than membrane technology alone

The world market for Ultrapure water is currently estimated at around US$ 2.3 billion per annum. Specialised journals dedicated to this subject are published within the water treatment world, where “everybody” uses the term ultrapure water. However, the time when it was enough to use a reverse osmosis (RO) system followed by ion exchange to produce ultrapure water seems like a long time ago, although in fact it is only about 20 years! Today, the demand for purity comes from the semiconductor industry, which sometimes requires purities that are beyond the detection limit of existing analytical equipment. To counter this, the approach towards the production of Ultrapure water has shifted from a series of unit operations to an integrated system design. In this article, Dr Tony Franken from the Membraan Applicatie Centrum Twente (MACT) in The Netherlands gives an insight into the production of ultrapure water.     

Application of cleaner technologies in milk processing industry to improve the environmental efficiency

Changes in production processes and products that result in improvement of environmental, economic and social performance of enterprises are an important element of the overall process towards more sustainable production. The aim of this article is to demonstrate the application of cleaner production and eco-design as sustainable production tools to improve the environmental efficiency of milk processing industry. Milk processing industry is one of the largest and dynamically developing branches of industry in the world. The main impact of milk processing industry on the environment is related to energy and water consumption, and waste and wastewater generation. A number of potential solutions to improve the environmental performance of milk processing industry, to reduce energy and resources consumption are analysed: substitution of cleaning agent in the milk receiving bar for washing of milk tankers with the specialised acidic detergent, integration of the automated CIP washing system in the butter bar, implementation of water recycling system to collect warm (35?°C) water, integration of the membrane technologies for the evaporation process and the use of filtrate received during the condensation for steam generation in the boiler house. Finally, an eco-design solution for cans of milk products is presented. All these proposals have been implemented in the milk processing company.     

复合半导体纳米材料的研究与制备

综述了纳米半导体的特性及应用,以及复合半导体纳米微粒的类型及其制备等方面的进展。     

Total precision inspection of machine tools with virtual metrology

The technology of virtual metrology (VM) has been applied in the semiconductor industry to convert sampling inspection with metrology delay into real time and online total inspection. The purpose of this study is trying to apply VM for inspecting machining precision of machine tools. However, machining processes will cause severe vibrations that make process data collection, data cleaning, and feature extraction difficult to handle. Thus, the tasks of how to accurately segment essential parts of the raw process data from the original numerical-control file, how to effectively handle raw process/sensor data with low signal-to-noise ratios, and how to properly extract significant features from the segmented and clean raw process data are challenging issues for successfully applying VM to machine tools. These issues are judiciously addressed and successfully resolved in this paper. Testing results of machining standard workpieces and cellphone shells of two three-axis CNC machines show that the proposed approach of applying VM to accomplish total precision inspection of machine tools is promising.     

碳酰氟的研究进展

碳酰氟是一种应用于半导体设备刻蚀和清洗的新型材料,在有机合成及氟化物的干燥、纯化领域也有重要应用。目前国内外关于碳酰氟的制备报道有很多,根据原料种类大体可分为四类,其中CO作为原料制备碳酰氟是应用最多的方法。作为应用于半导体行业的电子气体,对于纯度有一定的要求,因此碳酰氟的纯化也是制约其工业化应用的重要因素。     

REMOVAL OF SILICA PARTICLES FROM SILICON SUBSTRATES USING MEGASONIC CLEANING

Non-contact surface cleaning is a desirable process in many surface cleaning applications in the semiconductor, hard disk, and flat panel display industries. The effects of power, temperature, and time on the removal efficiency of silica particles from silicon wafers are presented. Results show that removal efficiencies near 100% could be achieved using deionized water and SCI under the right conditions. Megasonic power exerts a greater influence on particle removal efficiency than does temperature, both in water and in SCI solution. Particle removal efficiency decreases when the ammonia content is decreased slightly from the 5:1:1 ratio, but increases again as ammonia content is further decreased. The efficiency then remains high, even for R as low as 0.01.     

Microwave plasma removal of sulphur hexafluoride

Sulphur hexafluoride (SF(6)) gas is a common pollutant emitted during the plasma etching of thin films and plasma cleaning chemical vapor deposition (CVD) production processes used in the semiconductor industry. In this paper a method using microwave (2.45GHz frequency) plasmas sustained at atmospheric pressure for the abatement of SF(6) is investigated experimentally for various gas mixture constituents and operating conditions, with respect to its ability to decompose SF(6) to less harmful molecules. The destruction and removal efficiencies (DRE) of plasma abatement of SF(6) at concentrations between 1.7 and 5% in nitrogen in the presence of water vapor were studied as a function of the total gas flow rate and microwave power. Water vapor proved to be an effective source of free radical species that reacts with the radicals and ions resulting from SF(6) fragmentation in the plasma and also, it proved to reduce the process by-products. It was measured that approximately 25% of the initial SF(6) is converted to SO(2). Destruction and removal efficiencies of SF(6) up to 99.9% have been achieved.     

超临界CO2清洗技术的应用研究进展

超临界CO2清洗在技术、经济和环保领域的独特优势,使其具有广阔的应用前景.文章主要介绍了超临界CO2清洗技术在电子元器件、核工业、精密机械、医疗器械、纺织领域、光学工业和国防工业的应用进展.     

Environmental safety issues for semiconductors (research on scarce materials recycling)

In the 21st century, in the fabrication of various industrial parts, particularly, current and future electronics devices in the semiconductor industry, environmental safety issues should be carefully considered. We coined a new term, environmental safety issues for semiconductors, considering our semiconductor research and technology which include environmental and ecological factors. The main object of this analysis is to address the present situation of environmental safety problems in the semiconductor industry; some of which are: (1) the generation and use of hazardous toxic gases in the crystal growth procedure such as molecular beam epitaxy (MBE) and metalorganic chemical vapor deposition (MOCVD), (2) the generation of industrial toxic wastes in the semiconductor process and (3) scarce materials recycling from wastes in the MBE and MOCVD growth procedure.     

REMOVAL OF SILICA PARTICLES FROM SILICON SUBSTRATES USING MEGASONIC CLEANING

ABSTRACT

Non-contact surface cleaning is a desirable process in many surface cleaning applications in the semiconductor, hard disk, and flat panel display industries. The effects of power, temperature, and time on the removal efficiency of silica particles from silicon wafers are presented. Results show that removal efficiencies near 100% could be achieved using deionized water and SCI under the right conditions. Megasonic power exerts a greater influence on particle removal efficiency than does temperature, both in water and in SCI solution. Particle removal efficiency decreases when the ammonia content is decreased slightly from the 5:1:1 ratio, but increases again as ammonia content is further decreased. The efficiency then remains high, even for R as low as 0.01.     

循环风量对新型家用半导体纯净水机系统性能的影响

针对目前家用净水机需要频繁清洗和更换滤芯的问题,本文提出并搭建了一种利用半导体珀尔贴效应和空气增湿去湿原理相结合的家用净水系统,实验研究了循环风量对系统运行工况、功耗、单位时间产水量和单位能耗产水量的影响。实验结果表明：随着循环风量的增加,半导体冷热端温度逐渐下降,冷热端温差略有下降,系统制冷量、半导体功耗和制冷性能系数(COP)逐渐上升。当循环风量为100 m3/h,单位时间产水量和单位能耗产水量达到峰值,分别为345 g/h、459 g/(kW?h)。系统所制取水的卫生指标(TDS＜3 mg/L)符合国家饮用水标准,系统日产水量(＞7.2 L/d)满足一般家庭饮水需求。     

Semiconductor Metal–Organic Frameworks: Future Low‐Bandgap Materials

Metal–organic frameworks (MOFs) with low density, high porosity, and easy tunability of functionality and structural properties, represent potential candidates for use as semiconductor materials. The rapid development of the semiconductor industry and the continuous miniaturization of feature sizes of integrated circuits toward the nanometer (nm) scale require novel semiconductor materials instead of traditional materials like silicon, germanium, and gallium arsenide etc. MOFs with advantageous properties of both the inorganic and the organic components promise to serve as the next generation of semiconductor materials for the microelectronics industry with the potential to be extremely stable, cheap, and mechanically flexible. Here, a perspective of recent research is provided, regarding the semiconducting properties of MOFs, bandgap studies, and their potential in microelectronic devices.     

Will Future Measurement Needs of the Semiconductor Industry Be Met?

We discuss the ability of the nation’s measurement system to meet future metrology needs of the semiconductor industry. Lacking an acceptable metric for assessing the health of metrology for the semiconductor industry, we identify a limited set of unmet measurement needs. Assuming that this set of needs may serve as proxy for the galaxy of semiconductor measurement needs, we examine it from the perspective of what will be required to continue the semiconductor industry’s powerful impact in the world’s macro-economy and maintain its exceptional record of numerous technological innovations. This paper concludes with suggestions about ways to strengthen the measurement system for the semiconductor industry.