Semiconductor surface acoustic wave device
AssigneeInternational Business Machines Corporation
InventorRobert W. Keyes
Life of this patent
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Abstract
Surface acoustic wave devices with selectable performance parameters such as having a temperature coefficient of zero, may be fabricated employing a monocrystalline semiconductor substrate with a combination of appropriate doping and crystallographic orientation both with respect to the surface and the direction of propagation. Monocrystalline silicon doped with phosphorous to the order of 2.times.10.sup.19 atoms per cc, exhibits a zero temperature coefficient at 300.degree. Kelvin for acoustic waves propagating in the [110] crystallographic direction on a [110] substrate.
Claims10
In a device wherein semiconductor signal processing and surface wave propagation are employed in single substrate the improvement for surface wave propagation to eliminate the use of multi-material substrates comprising a monolithic semiconductor material substrate having a surface orientation and a direction of propagation in which said surface wave velocity is affected by doping with at least one of donors and acceptors, and a doping level in at least a region of said substrate operable to reduce the effect of temperature on the propagation time of a surface acoustic wave in said semiconductor material.
A surface acoustic wave semiconductor device having a reduced variation with temperature of propagation time of surface acoustic waves comprising:
- a monolithic semiconductor material substrate
- having both a surface orientation and a direction of propagation in which the velocity is affected by impurity doping, and
- having a doping level that reduces the effect of temperature on the propagation time of surface acoustic waves in said semiconductor.
A method of reducing the effect of temperature on the propagation time of surface acoustic waves in a semiconductor material comprising:
- selecting a surface orientation and a direction of propagation in said semiconductor material in which the velocity of surface wave propagation is affected by impurity doping;
- and
- providing impurity doping in a region of said semiconductor material at a level operable to reduce the effect of temperature on the propagation time of a surface acoustic wave.
A semiconductor device comprising a monolithic substrate having at least in a first region semiconductor signal processing capability and having at least in a second region surface acoustic wave propagation capability said acoustic wave propagation capability comprising a crystalline orientation both with respect to the direction of propagation of surface waves and a surface of said second region in which the direction of propagation of said waves is affected by doping and a doping level in said region operable to reduce the effect of temperature on the propagation time of said acoustic waves.
Dependencies are inferred from the claim text.