Semiconductor Device Having Magnetoresistive Element and Manufacturing Method Thereof

A method of manufacturing a semiconductor device comprising the steps of:

• forming a magnetoresistive element over a main surface of a semiconductor substrate;
• forming a bit line extending in a predetermined direction just above the magnetoresistive element at a distance, the bit line having an upper surface;
• forming an antidiffusion film in contact with the upper surface of the bit line, the antidiffusion film for preventing diffusion of an interconnect material of the bit line;
• forming a laminate film in contact with an upper surface of the antidiffusion film;
• and
• forming a yoke cover for shielding a magnetic field generated by a current flowing through the bit line by applying fabrication to the laminate film, and further including a step of:
• introducing, between the step of forming the antidiffusion film and the step of forming the laminate film, a metal material to the antidiffusion film thereby forming a mixing layer containing the metal material, the mixing layer extending from an upper surface of the antidiffusion film to a predetermined depth of the antidiffusion film,
• wherein the step of forming the laminate film includes the steps of:
• forming a magnetic layer in contact with an upper surface of the antidiffusion film, and
• forming an adhesion layer in contact with the surface of the magnetic layer, and
• wherein the step of forming the yoke cover includes:
• a step of forming a resist mask so as to cover a region arranged just above the bit line over the surface of the adhesion layer;
• a first step of patterning the adhesion layer by applying reactive ion etching with a halogen-based gas using the resist mask as an etching mask;
• a second step of applying reactive ion etching with ammonia and an argon-based gas using the patterned adhesion layer as an etching mask;
• and
• a third step of applying reactive ion etching with a gas containing carbon as an element by using the patterned adhesion layer as an etching mask.

A semiconductor device comprising:

• a magnetoresistive element formed over a main surface of a semiconductor substrate;
• a bit line having an upper surface and extending in a predetermined direction just above the magnetoresistive element at a distance;
• and
• a yoke cover covering the upper surface of the bit line and capable of shielding a magnetic field generated by a current flowing through the bit line,
• wherein the yoke cover has a laminate film having a lamination facet with a forward tapered shape, and
• wherein the laminate film includes:
• a magnetic layer having an upper surface and a lower surface;
• and
• an upper adhesion layer in contact with the upper surface of the magnetic layer.

A semiconductor device comprising:

• a magnetoresistive element positioned between a digit line extending in a first direction below the magnetoresistive element and a bit line extending in a second direction above the magnetoresistive element, the bit line having an upper surface;
• a layer in contact with the bit line;
• and
• a yoke cover positioned over the bit line and configured to shield a magnetic field generated by a current flowing in the bit line, the yoke cover comprising at least:
• a magnetic layer having an upper surface;
• and
• an upper adhesion layer in contact with the upper surface of the magnetic layer, with the magnetic layer being closer to the bit line than the upper adhesion layer;
• wherein:
• in a cross-sectional view of the semiconductor device taken transverse to the bit line, the magnetic layer and the upper adhesion layer together have a tapered shape and converge in a direction away from the bit line.

A method of manufacturing a yoke cover for a magnetic random access memory comprising a magnetoresistive element positioned between a digit line extending in a first direction below the magnetoresistive element and a bit line extending in a second direction above the magnetoresistive element, the method comprising:

• forming a laminate film over the bit line by:
• forming a lower adhesion layer over the bit line, the lower adhesion layer having an upper surface;
• forming a magnetic layer in contact with the lower adhesion layer, the magnetic layer having an upper surface;
• and
• forming an upper adhesion layer in contact with the upper surface of the magnetic layer, the upper adhesion layer having an upper surface;
• forming a resist mask over the bit line;
• patterning the upper adhesion layer by applying reactive ion etching with a halogen-based gas by using the resist mask as an etching mask;
• applying reactive ion etching with ammonia and argon-based gas by using the patterned upper adhesion layer as an etching mask;
• and
• applying reactive ion etching with a gas containing carbon as an element by using the patterned upper adhesion layer as an etching mask;
• such that:
• in a cross-sectional view of the semiconductor device taken transverse to the bit line, the lower adhesion layer, the magnetic layer and the upper adhesion layer together have a tapered shape and converge in a direction away from the bit line.