Semiconductor interlevel shorts caused by hillock formation in Al-Cu metallization

Puttlitz, Albert F.; Ryan, James G.; Sullivan, Timothy D.

doi:10.1109/33.49025

Cited by 27 publications

(6 citation statements)

References 12 publications

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“…32 With these values, the thickness of the consumed Ti layer would be 59 nm at 450°C and 357 nm at 550°C after annealing for 30 min. [33][34][35] The formation of TiN is detected by x-ray diffraction after annealing at 700°C. The 80 nm-thick Ti layer is reacted about half way at 550°C (Fig.…”

Section: Discussionmentioning

confidence: 99%

Reaction of aluminum-on-titanium bilayer with GaN: Influence of the Al:Ti atomic ratio

Gasser

Kolawa

Nicolet

1999

J. Electron. Mater.

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Section: Discussionmentioning

confidence: 99%

Reaction of aluminum-on-titanium bilayer with GaN: Influence of the Al:Ti atomic ratio

Gasser

Kolawa

Nicolet

1999

J. Electron. Mater.

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“…The enhanced formation of hillocks is attributed to the increase in substrate temperature with the application of radio frequency ͑rf͒ power. 15,16 To determine which factor controls hillock formation, the wafer temperature was measured in situ during plasma cleaning. Results indicate that the temperature range was 250-320°C during H 2 /N 2 plasma cleaning, as shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Avoiding Cu Hillocks during the Plasma Process

Kang

Chou

2004

J. Electrochem. Soc.

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When Cu wafers are exposed to H 2 /N 2 plasma, hillocks are formed on the Cu wafer surface by a plasma cleaner with a surface wave plasma source. Plasma cleaning is divided into the initial stage and the rising temperature stage. Under a supply of H 2 /N 2 gas and with the plasma power turned on, the H radicals first restore native copper oxide to pure copper. The N radicals then compete with the H radicals, and diffuse to the Cu grain boundary, which is the initial stage. During the rising temperature stage, plasma energy is absorbed by the Cu surface, and the wafer temperature increases rapidly. Consequently, plasma-enhanced compressive stress leads to the formation of Cu hillocks. For a plasma with a higher N/H radical ratio, more N radicals diffusing to the Cu grain boundary results in more Cu-N compounds, which make up the main source of stress during H 2 /N 2 plasma cleaning. Experimental results indicate that using a plasma cleaner with an inductively coupled plasma source can achieve a lower N/H radical ratio, thus avoiding the formation of Cu hillocks.The Cu dual damascene process has been widely employed for fabricating multilevel interconnection schemes in ultralarge scale integration ͑ULSI͒ circuits. This is because Cu dual damascene wiring provides significant advantages over the conventional Al metallization process. Therefore, many issues related to this process have been studied in detail. 1-5 Some of these issues affect the yield of the via chain. 4-6 The first via approach for the dual damascene structure consists of the following sequence. ͑i͒ Via etching through the whole dielectric stack (trench ϩ via), and then bottom antireflective coating ͑BARC͒ via filling, (ii) trench lithography, (iii) BARC etch back, (iv) trench etching in fluorinated silicate glass ͑FSG͒, and then O 2 -based plasma cleaning, and (v) capping nitride removal, and then O 2 -based plasma cleaning. The schematic process is shown in Fig. 1. Sometimes, it is difficult to stop the etch on the thin nitride film during via etching due to low or unstable oxide/nitride selectivity. Therefore, the Cu underlayer will be exposed to air after via etching. Moreover, it is observed that using only wet solvent cleaning after nitride removal will result in some residue, as shown in Fig. 2. Therefore, it is also necessary to use plasma cleaning after nitride removal. For conventional postetch cleaning technology used in the Al interconnection process, most recipes use O 2 -based plasma with high temperatures of 250-275°C. Even though the Al underlayer is exposed to air after via or trench etching, it is notable that the thin Al 2 O 3 compound on Al surfaces is not oxidized continuously during O 2 -based plasma cleaning. However, the weak Cu oxide on the Cu surface cannot provide an effective barrier to prevent Cu bulk from continuous oxidization at high temperature. These copper oxides may possibly cause difficulty in subsequent cleaning and reduction in interconnection yield. Therefore developing a new dry cleaning technology for Cu dual...

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“…In figure 3 (d) a hillock between M1 and M2 layers is shown. These defects are generated by the thermal relaxation of the different layer materials [10,11]. In fact, due to the different coefficient of thermal expansion for Si and Al (the latter 10 times larger [11]), the thermal cycles that the sensor undergoes during production induce compressive stresses in the first Al layer.…”

Section: Pxd9 Quality Assurancementioning

confidence: 99%

Production quality characterisation techniques of sensors and prototypes for the BELLE II Pixel Detector

et al. 2015

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The Belle II detector is a system currently under upgrade at the B-factory SuperKEKB in Tsukuba, Japan. The main novelty is the introduction of an additional position sensitive subdetector in the vertex detector, between the beam pipe and the strip detector system. The sensor of choice for the Belle II Pixel Detector is the Depleted p-channel Field Effect Transistor (DEPFET) sensor. In this paper the latest production of sensors and prototypes performed at the semiconductor Laboratory of the Max Planck Society, i.e. the PXD9 and the Electrical Multi-Chip Module (EMCM), are described. Wafer-level characterisation methods and techniques for faults in the metal system are also reported.

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Semiconductor interlevel shorts caused by hillock formation in Al-Cu metallization

Cited by 27 publications

References 12 publications

Reaction of aluminum-on-titanium bilayer with GaN: Influence of the Al:Ti atomic ratio

Reaction of aluminum-on-titanium bilayer with GaN: Influence of the Al:Ti atomic ratio

Avoiding Cu Hillocks during the Plasma Process

Production quality characterisation techniques of sensors and prototypes for the BELLE II Pixel Detector

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