Niu Xinhuan

An advanced alkaline slurry for barrier chemical mechanical planarization on patterned wafers

We have developed an alkaline barrier slurry (named FA/O slurry) for barrier removal and evaluated its chemical mechanical planarization (CMP) performance through comparison with a commercially developed barrier slurry. The FA/O slurry consists of colloidal silica, which is a complexing and an oxidizing agent, and does not have any inhibitors. It was found that the surface roughness of copper blanket wafers polished by the FA/O slurry was lower than the commercial barrier slurry, demonstrating that it leads to a better surface quality. In addition, the dishing and electrical tests also showed that the patterned wafers have a lower dishing value and sheet resistance as compared to the commercial barrier slurry. By comparison, the FA/O slurry demonstrates good planarization performance and can be used for barrier CMP.

Planarization properties of an alkaline slurry without an inhibitor on copper patterned wafer CMP

The chemical mechanical polishing/planarization (CMP) performance of an inhibitor-free alkaline copper slurry is investigated. The results of the Cu dissolution rate (DR) and the polish rate (PR) show that the alkaline slurry without inhibitors has a relatively high copper removal rate and considerable dissolution rate. Although the slurry with inhibitors has a somewhat low DR, the copper removal rate was significantly reduced due to the addition of inhibitors (Benzotriazole, BTA). The results obtained from pattern wafers show that the alkaline slurry without inhibitors has a better planarization efficacy; it can planarize the uneven patterned surface during the excess copper removal. These results indicate that the proposed inhibitor-free copper slurry has a considerable planarization capability for CMP of Cu pattern wafers, it can be applied in the first step of Cu CMP for copper bulk removal.

Application of a macromolecular chelating agent in chemical mechanical polishing of copper film under the condition of low pressure and low abrasive concentration

The mechanism of the FA/O chelating agent in the process of chemical mechanical polishing (CMP) is introduced. CMP is carried on a Φ300 mm copper film. The higher polishing rate and lower surface roughness are acquired due to the action of an FA/O chelating agent with an extremely strong chelating ability under the condition of low pressure and low abrasive concentration during the CMP process. According to the results of several kinds of additive interaction curves when the pressure is 13.78 kPa, flow rate is 150 mL/min, and the rotating speed is 55/60 rpm, it can be demonstrated that the FA/O chelating agent plays important role during the CMP process.

Removal of residual CuO particles on the post CMP wafer surface of multi-layered copper

This article introduces the removal technology of CuO particles on the post CMP wafer surface of multi-layered copper. According to the Cu film corrosion curve with different concentrations of H2O2 and the effect curve of time on the growth rate of CuO film, CuO film with the thickness of 220 nm grown on Cu a surface was successfully prepared without the interference of CuCl2-2H2O. Using the static corrosion experiment the type of chelating agent (FA/O II type chelating agent) and the concentration range (10–100 ppm) for CuO removal was determined, and the Cu removal rate was close to zero. The effect of surfactant on the cleaning solution properties was studied, and results indicated that the surfactant has the effect of reducing the surface tension and viscosity of the cleaning solution, and making the cleaning agent more stable. The influence of different concentrations of FA/O I type surfactant and the mixing of FA/O II type chelating agent and FA/O I type surfactant on the CuO removal effect and the film surface state was analyzed. The experimental results indicated that when the concentration of FA/O I type surfactant was 50 ppm, CuO particles were quickly removed, and the surface state was obviously improved. The best removal effect of CuO on the copper wiring film surface was achieved with the cleaning agent ratio of FA/O II type chelating agent 75 ppm and FA/O I type surfactant 50 ppm. Finally, the organic residue on the copper pattern film after cleaning with that cleaning agent was detected, and the results showed that the cleaning used agent did not generate organic residues on the film surface, and effectively removes the organic residue on the wafer.

Effect of three kinds of guanidinium salt on the properties of a novel low-abrasive alkaline slurry for barrier CMP

The influence of three kinds of guanidinium salt on the removal rate selectivity of different materials was studied during the barrier chemical mechanical polishing (CMP) process at first. The three kinds of guanidine saltguanidine hydrochloride, guanidine nitrate and guanidine carbonate. Then we compared the effect of the three kinds of guanidine salt on the dishing, erosion and surface roughness value. In the end, the reaction mechanism was studied through electrochemical analysis. All the results indicate that there is a better performance of the slurry with guanidine hydrochloride than the slurries with the other two kinds of guanidine salt. It effectively improved the removal rate selectivity and the surface roughness under the premise of low abrasive concentration and low polishing pressure, which is good for the optimization of the alkaline slurry for the barrier CMP process.

A new kind of chelating agent with low pH value applied in the TSV CMP slurry

TSV (through silicon via) is an emerging technology, which can realize micromation compared with the conventional packaging and extend Moores law. Chemical mechanical polishing (CMP) is one of the most important steps in the process of TSV manufacture, and it is an enabling technology to extend Moores law in the past two decades. Low pressure, low abrasive and low pH value are the main requirements for copper interconnection. In this paper, the effect of different kinds of TSV slurry with FA/O II or FA/O IV type chelating agent on CMP are studied. All kinds of slurry used in this study are alkaline with no added inhibitors. From the experiment results, it can be seen that the copper removal rate and surface roughness achieved by using the FA/O IV type chelating agent with a low pH value is superior to using the FA/O II type chelating agent.

A novel kind of TSV slurry with guanidine hydrochloride

The effect of a novel alkaline TSV (through-silicon-via) slurry with guanidine hydrochloride (GH) on CMP (chemical mechanical polishing) was investigated. The novel alkaline TSV slurry was free of any inhibitors. During the polishing process, the guanidine hydrochloride serves as an effective surface-complexing agent for TSV CMP applications, the removal rate of barrier (Ti) can be chemically controlled through tuned selectivity with respect to the removal rate of copper and dielectric, which is helpful to modifying the dishing and gaining an excellent topography performance in TSV manufacturing. In this paper, we mainly studied the working mechanism of the components of slurry and the skillful application guanidine hydrochloride in the TSV slurry.