Composite mass air flow sensor

A mass air flow sensor comprising:

• a generally planar glass substrate having an upper surface, a lower surface and an air flow opening formed therethrough;
• a first silicon member having a bottom surface, a portion of the first silicon member extending over the air flow opening and a portion of the bottom surface of the first silicon member being bonded at a bonding site to an underlying portion of the upper surface of the glass substrate;
• an electrically heatable element comprising a resistive film on the first silicon member;
• and
• a silicon frame spaced from the first silicon member and bonded to the upper surface of the glass substrate around the air flow opening.

A mass air flow sensor comprising:

• a generally planar glass substrate having an upper surface, a lower surface and an air flow opening formed therethrough, a first peninsula and a second peninsula of the glass substrate extending generally parallel each other into the air flow opening;
• a first electrically conductive lead extending on the upper surface of the glass substrate from a first electrical contact point on the first peninsula to a first wire bond pad remote therefrom;
• a second electrically conductive lead extending on the upper surface of the glass substrate from a second electrical contact point on the first peninsula to a second wire bond pad remote therefrom;
• a third electrically conductive lead extending on the upper surface of the glass substrate from a third electrical contact point on the second peninsula to a third wire bond pad remote therefrom;
• a fourth electrically conductive lead extending on the upper surface of the glass substrate from a fourth electrical contact point on the second peninsula to a fourth wire bond pad remote therefrom;
• a first silicon beam having a planar top surface, a planar bottom surface wider than its top surface and a trapezoidal cross-section, a portion of the bottom surface of the first silicon beam being bonded at a first bonding site on the first peninsula to an underlying portion of the upper surface of the glass substrate, covering the first and second electrical contact points, and a free end of the first silicon beam being cantilevered over the air flow opening;
• a first resistive element comprising an elongate metal resistive thin film extending on the bottom surface of the first silicon beam from electrical contact with the first electrically conductive lead at the first electrical contact point toward the free end of the first silicon beam and back to electrical contact with the second electrically conductive lead at the second electrical contact point;
• a second silicon beam having a planar top surface, a planar bottom surface wider than its top surface and a trapezoidal cross-section, a portion of the bottom surface of the second silicon beam being bonded at a second bonding site on the second peninsula to an underlying portion of the upper surface of the glass substrate, covering the third and fourth electrical contact points, and a free end of the second silicon beam being cantilevered over the air flow opening;
• a second resistive element comprising an elongate metal resistive thin film extending on the bottom surface of the second silicon beam from electrical contact with the third electrically conductive lead at the third electrical contact point toward the free end of the second silicon beam and back to electrical contact with the fourth electrically conductive lead at the fourth electrical contact point;
• and
• a silicon frame bonded to the upper surface of the glass substrate around the air flow opening remote from the first silicon beam and the second silicon beam, the silicon frame having a top surface coplanar with the top surface of the first silicon beam and the top surface of the second silicon beam.