Nitric acid-based slurry with citric acid as an inhibitor for copper chemical mechanical polishing

Review on copper chemical–mechanical polishing (CMP) and post-CMP cleaning in ultra large system integrated (ULSI)—An electrochemical perspective

“…Addition of BTA results in the formation of tightly adherent Cu-BTA protective layer film at the metal surface [32][33][34][35][36][37][38], which blocks copper surface removal, leading to a decrease in copper dissolution rate. Many authors [23,27,30,39] indicated that this protective layer may posses the characteristics of a passive oxide film during CMP process: a removal of copper-inhibitor film from the surface of the copper during CMP would result in an active dissolution of bare copper sites. Recovering and reformation of a protective film at these sites during further exposure would decrease the dissolution rate.…”

Effects of hydrogen peroxide and alumina on surface characteristics of copper chemical–mechanical polishing in citric acid slurries

“…Citric acid is also known to be a chelating agent for Cu 2+ ions [16]. However, in 3 vol.% HNO 3 oxidizing slurry, highly concentrated citric acid was found to inhibit the etching rate in Cu CMP [9]. The co-existence of oxidizing and complexing agents in the slurry seems to have complicated effect on Cu CMP.…”

“…Several kinds of oxidizing agents, such as H 2 O 2 [5,6,8], HNO 3 [7][8][9][10][11], Fe(NO 3 ) 3 [8,12], NaClO 3 [13] and KIO 3 [14], among others, have been used to form a passive film on a copper surface or to dissolve it into slurries. Although the oxidizing powers of these agents are known, the specific roles of these agents on Cu CMP were not as clear as that found in W CMP [1] or Al CMP [2][3][4]15].…”

Effects of electric potential on chemical-mechanical polishing of copper

“…[5][6][7][8][9][10] In acidic media, an inhibitor, benzotriazole, is used to control the removal rate and avoid isotropic etching. 5,6 In neutral polish slurries, H 2 O 2 has been used as an oxidizer.…”

“…[5][6][7][8][9][10] In acidic media, an inhibitor, benzotriazole, is used to control the removal rate and avoid isotropic etching. 5,6 In neutral polish slurries, H 2 O 2 has been used as an oxidizer. [7][8][9] The Cu CMP in ammonia-containing slurries have been investigated extensively by Steigerwald et al [11][12][13][14][15][16] They concluded that the mechanism for copper removal is the mechanical removal of copper, followed by the dissolution of abraded copper particles.…”