PCD dressers for making CMP pad conditioners

Diamond pad conditioners are indispensable for chemical mechanical planarization (CMP) of sophisticate integrated circuits for semiconductor manufacture. The pad conditioner is used to dress the polishing pad to form asperities that determine the efficiency of CMP processes and the quality of polished wafers. The polishing rate of a wafer is primarily controlled by the amplitude (height) of the asperities on the pad surface; and the polishing uniformity, by the frequency (density) of such asperities. Current diamond pad conditioners cannot create effectively the amplitude nor the density of dressed pad asperities. This is because the tips of diamond grits are not leveled to the same height due to the intrinsic spread of particle sizes the random orientation of diamond crystals. Moreover, diamond grits are different in shapes, so their cutting behaviors are not predictable. Consequently, the dressed pad surface will show uneven texture with variable asperities. As a result, the polishing of expensive semiconductor wafers may vary in polishing rate, wafer uniformity, and defect counts. Instead of attaching individual diamond grits to a metal substrate, a revolutionary design of pad conditioners is made by carving the structure out of a strong polycrystalline diamond (PCD) matrix that is sintered at ultrahigh pressure (6 GPa) and with high temperature (1350°C). Such Advanced Diamond Disks (ADD) are manufactured by electro discharge machining (EDM) of PCD to form cutting pyramids of a specific size with a designed shape. These pyramids can be distributed in a predetermined pattern. This is not possible with single crystal diamond grits that possess obtuse solid angles for cutting. ADD can produce a much higher density of pad asperities for polishing wafers at high efficiency and with high uniformity. The test data confirmed that ADD can dress pad more effectively than conventional pad conditioners with discrete diamond grits. Moreover, the service lives of ADD as well as pad can be both lengthened due to the much milder dressing action. In addition, ADD may be resurfaced after their cutting edges become dull so the pad conditioners can be used over and over again. These unique features of ADD can reduce significantly the cost of consumable (CoC) of CMP for the manufacture of advanced semiconductors.