Development of Pad Conditioner Drop Detection System Dissertation

Development of Pad Conditioner Drop Detection System - Dissertation Example The project focuses on the design of a sensor system that can trigger accumulation of copper on the pad or detect the optimal parameters of the CMP equipment. Contents Development of Pad Conditioner Drop Detection System 30 1 1.0 Introduction 5 1.1 Background information 5 1.2 Statement of the problem 6 1.3 Statement of the problem 8 On 13h Dec 2010 PCUD712 went to check P2 trace and found Cu was not fully polished at wafer. This problem of having wafer edges that are not fully polished has caused the need for this project. No one did recognize the occurrence of the problem until one of the maintenance team did a random testing. Making CMP equipment that has a sensor can trigger any drop caused by the presence of copper and call for a response from the team. 8 1.4 Project scope 8 1.5 Objective 9 1.6 Specific objectives 9 2.0 literature Review 10 2.1 Types of planarization 10 2.1.1 Doped Glass Reflow 10 2.1.2 Spin etch planarization (SEP) 10 2.1.3 Spin on deposition (SOD) 11 SOP is mo stly applied in deposits on different glasses, porous low-k dielectrics and polymer ILD. By mixing different base catalysts and suitable additives, a precursor solution is prepared at room temperature. Pretreated wafer surface provides an effective surface for solution spreading. A little amount of the solution is dripped on the wafers that are then rinsed, spun dried baked and later cured. This process shows excellent gap filling qualities. Nevertheless, several defects are noted on the spin in the deposited materials. When the materials from this process are exposed to plasma, they show non-homogeneity in subsequent operations. Undue stresses are induced by the tendency of the spin to absorb moisture from the air and releasing it with evolution of thermal stresses. The stresses result to cracking, peel off, shrinking, degradation and contamination of interconnects and thermal instability. 11 2.1.4 Reactive ion etch and etch back 11 2.1.5 Chemical mechanical polishing 12 Historical ly, grinding has always been an inexpensive operation compared to polishing. The level of polishing required nowadays in the IC fabrication can not be matched to these advantages (Yoshio, 2000). Unlike grinders, polishers use elastic media to sever bonds on a molecular level ejecting nanometer sized particles. The grinders’ use rigid media that create cracks through a work piece, the clusters are micron sized. Recent research has shown that the maximum force is a key variable of sub surface damage (Chandra etal., 2000 p.81). CMP focuses on the insights accruing from the investigations on minimizing force/grit by applying knowledge of errant particles that plague polishing processes (Chandra & Bastawros, 2004 p.65). The process involves incorporating the wafer pattern into a gimbal and replacing the polishing pad with two diametrically opposing wheels. The trapped particles will induce a torque on one of the wheels thereby making the gimbal rotate away from offending particle. Through optimization of the dynamics of the gimbals’ response to the acute forces resulting from the errant particles, a defect mitigating maximum-force minimization is realized at low cost. 15 2.2 IC interconnects 17 2.3 Photometric dispersion analyzer (PDA 2000) 19 To monitor properties of flowing suspension and emulsions, a PDA 2000 is used both in laboratories