Effect of temperature on copper damascene chemical mechanical polishing process

Abstract

The effects of different process parameters on tribology and surface defects were studied till date, but there has been minimal study to understand the effect of temperature on the copper chemical mechanical polishing ͑CMP͒ process. The effect of temperature on tribology and surface defects during copper CMP employing different pad materials and slurries has been explored. From the results, it was seen that the coefficient of friction and removal rate increased with an increase in slurry temperature during polishing. The experimental data indicated that the increase in temperature results in an increase in amounts of metal dishing and metal loss. The dishing and metal loss in the interconnect features initially increased with an increase in temperature and then decreased at elevated temperatures. With an increase in temperature the copper films peeled off from the wafer due to low adhesion with low-k dielectric material at higher temperatures. The electrical properties of the planarized devices showed drastic degradation with increase in dishing values. Also the temperature showed a significant effect on pad physical and mechanical properties with an increase in temperature. The increase in temperature also increased the crystallinity of the copper film.

A wafer-scale material removal rate profile model for copper chemical mechanical planarization

“…The CMP process requires mechanical energy to remove the target material from the wafer surface. A certain amount of this energy is converted into heat, resulting in an increase in the pad temperature, which in turn contributes greatly to the increase in chemical reaction rate in CMP [14].…”

“…Both reports demonstrated that the MRR in the oxide CMP process was affected by a change in process temperature. Generally, copper CMP is more thermally dependent than oxide CMP [14]. Therefore, it is essential to study the thermal effect on the copper CMP process.…”

A reliable control system for measurement on film thickness in copper chemical mechanical planarization system

“…2 So the condition of in situ measurement should be satisfied first when the method to measure the thickness of copper film is considered to choose. In recent years, a variety of in situ detection methods that make use of various principles, such as optical reflectance or frictional force, 10 have been put forward. Generally, the spectra of reflected light from different layers on a pattern wafer demonstrates a clear transition from copper to the underlying dielectric layer.…”

High-Performance Pad Conditioning (HPPC) Arm for Augmenting CMP Performance

“…[7][8][9][10][11][12] Consumables such as CMP pads, slurries, pad conditioners, retaining rings of the carrier are known to impact material removal rates, within-wafer non-uniformity (WIWNU), wafer-to-wafer non-uniformity (WTWNU), planarization efficiency that in turn impacts the dishing performance, (WIDNU) and the defectivity of ICs. [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] CMP consumable is another area that will require significant developments in addition to advances in hardware, to meet these stringent process requirements. Novel methods have been reported using advanced manufacturing technology to manufacture CMP pads.…”