Method for depositing an al.sub.2 O.sub.3 cap layer on an integrated circuit substrate

A method for fabricating an integrated circuit wafer in order to reduce film stress, the formation of mouse bites and notches during an etching step and to increase light absorption during a patterning step, said method comprising the steps of:

• positioning a thermally oxidized silicon wafer on a substrate holding fixture in a vacuum chamber;
• introducing argon gas into said vacuum chamber until a first sputtering pressure of about 6.times.10.sup.-3 TORR. is attained;
• depositing a layer of aluminum on said substrate by sputering with argon gas at said first sputtering pressure until said aluminum layer reaches a thickness of about 1 micron;
• depositing a layer of aluminum oxide on said aluminum layer by sputtering with an argon-oxygen gas mixture at a second pressure of about 1.times.10.sup.-2 TORR. until said aluminum oxide layer attains a thickness of about 300 Angstroms;
• photolithographically patterning a resist such that said aluminum oxide layer provides increased absorption of light during photolithography;
• etching said aluminum and aluminum oxide layers, whereby said aluminum oxide layer reduces formation of mouse bites and notches on said aluminum layer;
• and
• annealing said semi-conductor chip whereby said aluminum oxide layer manifests reduced film stress.

A method of forming a cap layer of aluminum oxide on an aluminum layer on a substrate for reducing film stress and the number of mouse bites and notches in said aluminum layer, comprising the steps of:

• depositing about a 1 micron thick layer of aluminum on said substrate, using an argon sputtering gas at a first pressure of about 6.times.10.sup.-3 TORR. wherein deposition of said aluminum layer occurs at a rate of 1400 .ANG./min. using a power setting of 8.5 Kw;
• depositing about a 300 Angstrom thick layer of aluminum oxide on said aluminum layer by sputtering aluminum in the presence of argon and oxygen gas at a second pressure of about 1.times.10.sup.-2 TORR., wherein deposition of said aluminum oxide layer occurs at a rate of 115 .ANG./min. using a power setting of 2.5 Kw;
• photolithographically patterning a resist such that said aluminum oxide layer provides increased absorption of light during patterning;
• and
• etching said layers wherein said aluminum oxide layer reduces formation of mouse bites and notches in said aluminum layer.