Characteristics of copper films produced via atomic layer deposition

Abstract

Properties of copper films produced using atomic layer deposition (ALD) were characterized. Composition, morphology, and electrical properties of these films grown on glass, as well as Ta, TiN, and TaN on silicon wafers were examined. The resistivity of films thicker than about 60 nm was near bulk value. Films were deposited using a two-step ALD process in which copper(II)-1,1,1,5,5,5,-hexafluoroacetylacetonate hydrate and water vapor were introduced in the first step and a reducing agent was introduced in a subsequent step. Five reducing agents were evaluated, with the best results obtained using isopropanol or formalin. The optimum deposition temperature with isopropanol was about 260 °C, whereas it was about 300 °C with formalin. These films were also investigated as seed layers for electrodeposition of thicker Cu layers for possible interconnect applications. Excellent fills in high aspect ratio trenches were demonstrated.

Radical-Enhanced Atomic Layer Deposition of Metallic Copper Thin Films

“…5 A limited number of publications have reported copper growth by ALD. [6][7][8][9][10][11] The deposition of copper with ALD still remains quite problematic. One reason for this appears to be a lack of a good reducing agent.…”

Copper Seed Layer Deposition by a New Liquid Precursor

“…Copper seed layers have conventionally been deposited using PVD, however deposition of conformal films by PVD methods is difficult and, as the device aspect ratios increase, it becomes increasingly difficult to deposit a continuous and uniform seed layer by PVD, so the CVD of copper has attracted considerable attention as an alternative method. [2] In CVD, a number of Cu I and Cu II precursors have been used in the form of different metalorganics [3][4][5][6][7] and halides. [8][9][10] Cu I precursors (especially for metal-organic Cu I precursors) are used to deposit the copper films by disproportional reactions, [11] and are thermally less …”

Radical‐Enhanced Atomic Layer Deposition of Silver Thin Films Using Phosphine‐Adducted Silver Carboxylates

“…[12] Generally, depositing elemental materials by ALD is challenging due to the lack of a broadly applicable reducing agent allowing the saturative exchange-type reactions for ALD of compound films. For example, copper deposition has been attempted with several reducing agents, elemental zinc, [13] alcohols, [14,15] and molecular hydrogen, [16][17][18][19][20] but none of them has proven to be a good all-round solution. Molecular hydrogen has been used successfully in thermal ALD using transition metal amidinates to deposit 408 Fe, Co, Ni, and Cu.…”