The cleaning at a back surface and edge of a wafer for introducing Cu metallization process

Itoh, M.; Ishii, Yohei; Jinbo, T.; Akimori, H.; Futase, Takuya; Saeki, Takaaki

doi:10.1109/66.857939

Cited by 8 publications

(8 citation statements)

References 6 publications

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“…This is far below the failure threshold of 5.0 ϫ 10 10 atom/cm 2 for copper at BEOL processes. 21,[26][27][28] The process time used in this work is shorter than that reported by Itoh et al 23 and the efficiency of cleaning is also better.…”

Section: Optimized Cleaning Processmentioning

confidence: 72%

Optimization of Back Side Cleaning Process to Eliminate Copper Contamination

Chou

Tsui

Kuo

et al. 2005

J. Electrochem. Soc.

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Copper ͑Cu͒ contamination at the wafer bevel, back side surface, and exclusion zone is identified step-by-step following a typical dual-damascene process. The shield ring of a physical vapor deposition system does not protect the exclusion zone and bevel efficiently. Also, Cu may dissolve and accumulate in the solvent used for post dielectric etch clean. Dissolved Cu atoms may then redeposit on the wafer surface. Furthermore, the rough back side surface traps Cu atoms easier than the smooth front side surface. If there is no SiO 2 film on the back side surface, post chemical mechanical polish cleaning using dilute HF cannot remove Cu at the back side surface. An optimized single-wafer spin-etch process was proposed. An optimal etchant consisting of HF, HNO 3 , H 2 SO 4 , and H 3 PO 4 with ratios 0.5:3:1:0.5 showed excellent performance. Experiments demonstrated that a very short, 10 s, back side clean can totally remove Cu from back side surface, bevel, and 2 mm exclusion zone. A ''wafer shift'' procedure was also proposed to solve the pinmark issue near the edge pin due to etchant remnant. The optimized cleaning technique shows shorter process time and higher cleaning efficiency than those reported previously.With the progress of integrated circuit ͑IC͒ processing technology, the feature size is scaled down continuously. As the device performance and the circuit density are improved due to shorter channel length and smaller device geometry, the resistance and capacitance of multilevel interconnects are increased due to the thinner and longer metal wires and the narrower space between them. Copper ͑Cu͒ has been recognized as the most suitable alternative for aluminum as an interconnect material because of its low electrical resistivity and excellent electromigration resistance.

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Section: Optimized Cleaning Processmentioning

confidence: 72%

Optimization of Back Side Cleaning Process to Eliminate Copper Contamination

Chou

Tsui

Kuo

et al. 2005

J. Electrochem. Soc.

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“…Moreover, there is a requirement to remove the contaminants from both the front and back sides or edge of the substrate. 8) The conventional Spot Shower cannot be applied to cleaning of the back side or edge owing to the limited space for installation. In addition, the installation of the Spot Shower is strongly limited because the sound pressure level of the emitted ultrasonic waves decreases significantly over 30 mm in distance.…”

Section: Introductionmentioning

confidence: 99%

Novel Ultrasonic Cleaning Equipment Using Waveguide Mode

Suzuki

Han²,

Okano³

et al. 2009

Jpn. J. Appl. Phys.

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The clarity of the trace testifies to the accuracy and stability of the apparatus. A test was also carried out on a non-inductive circuit carrying alternating current. With a supply voltage of 250 V. r.m.s. it was found that current interception could be secured at a current peak up to 300 mA. There was no difficulty in maintaining a steady break at a zero of current up to a r.m.s. current of I A. A discussion upon contact material, suppression of the arc, etc. will be found in referenceb) in the bibliography. APPLICATIONSExamples have been given of the recording of rapid 50 cis transients by means of this apparatus. At the other end of the scale, the recording of current surges in incandescent lighting loads, when a considerable time must be allowed for the lamps to heat and cool, may also be carried out. The apparatus has also a possible application in the production of very low frequency square waves to a high degree of precision. As at present in use by the authors, it has a lower switching frequency of 40 timesimin. (which can readily be reduced by slight modification to the multivibrator circuit) and an upper switching frequency of 12.5 times/sec. The duration of the on or off condition may be reduced to 3% sec. independently of the switching frequency. There is no reason why currents alternating at frequencies greater than 50 cis should not be switched but, assuming constant relay errors, the accuracy will fall proportionately as the frequency is raised. CONCLUSIONThe authors believe that this apparatus will be a valuable tool for research into the transient effects occurring in non-linear networks. It can be shown that the effect of such transients in circuits containing current transformers is to reduce permanently the accuracy of the transformer until, by some means, the resulting polarization of the magnetic core has been removed. It is believed that this effect results in 'through fault instability' in protection systems for power networks employing current transformers, and it is the authors' immediate object to use the apparatus described here to record the results of such transients using small current transformers as models of those used in power engineering. REFERENCES ( I ) SKILLING, H. H. ABSTRACT.A simple electrical viscometer has been designed enabling instantaneous indications of viscosities of liquids at any point in an industrial plant. The transmitter unit consists of a twophase electric motor operated from single-phase mains and SO designed and constructed that large variations of current in one phase are produced by small changes in viscous drag on the rotating part. The indicator unit is essentially an ammeter in one of the motor phases and is directly calibrated in viscosity units. Models have been designed for operation within pipe lines and containers up to high pressures and high temperatures (about 250' C.) and for rapid testing of samples. INTRODUCTIONFor some years now there has been a demand for a viscometer to indicate directly and continuously, without the necessity of taking...

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“…1) The purpose of post-CMP cleaning is to remove all contaminants from both the front and back sides of a wafer. 2) For single-wafer processing, a spin cleaner using spoutingtype ultrasonic cleaning equipment, called a Spot Shower, 3) has been developed.…”

Section: Introductionmentioning

confidence: 99%

Application of Novel Ultrasonic Cleaning Equipment Using Waveguide mode for Post-Chemical-Mechanical-Planarization Cleaning

Suzuki

Han²,

Okano³

et al. 2009

Jpn. J. Appl. Phys.

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In this paper, we propose the application of novel ultrasonic cleaning equipment using a waveguide mode, which we called the Megatube, to post chemical mechanical planarization (CMP) cleaning. Waveguides can be created in a curved shape, and ultrasonic waves of 1 MHz, within the megasonic frequency range, can propagate along such waveguides. It is possible to supply ultrasonic waves at a distance from the equipment, which has the advantage of enabling ultrasonic emission in a narrow space. For single-wafer processing, this technique has the advantage of removing particles, known as slurry residues, from both the front and back sides of the wafer by exposure to ultrasonic waves of megasonic frequency. In the Megatube, cavitation is generated by controlling the input power and the dissolved gas concentration. Particle removal efficiency (PRE) using the Megatube was evaluated for various input powers, waveguide tube lengths, and concentrations of dissolved gas in a cleaning solution.

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The cleaning at a back surface and edge of a wafer for introducing Cu metallization process

Cited by 8 publications

References 6 publications

Optimization of Back Side Cleaning Process to Eliminate Copper Contamination

Optimization of Back Side Cleaning Process to Eliminate Copper Contamination

Novel Ultrasonic Cleaning Equipment Using Waveguide Mode

Application of Novel Ultrasonic Cleaning Equipment Using Waveguide mode for Post-Chemical-Mechanical-Planarization Cleaning

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